ENGN UMR3047 THE SCOPE OF NUCLEAR ENERGY By H. A. Ohlgren To be Presented to The Science Club of Macalester College St. Paul, Minnesota November 16, 1955

TABLE OF CGONTENTS Page 1. 0 ABSTRACT 1 2.0 THE ENERGY RESOURCES OF THE WORLD 2 3.0 FIELDS AND ACTIVITIES INVOLVED IN NUCLEAR ENERGY 5 4.0 THE FISSION PROCESS 10 5.0 NUCLEAR REACTOR CLASSIFICATION AND GENERAL NUCLEAR REACTOR SCHEMES 12 6.O INTEGRATED NUCLEAR REACTOR SYSTEMS 24 7.0 FUEL SEPARATION 53 8.0 BY-PRODUCTS OF NUCLEAR ENERGY 62 9.0 GLOSSARY OF TERMS 83 ii

1.0 ABSTRACT The consumption of energy by the human population of the world is increasing due to population growth and improvements of standards of living. Extrapolation indicates that reserves of fossil fuels cannot economically provide expected energy demands. By extraction of energy from the sun and controlled use of energy of fission and fusion, it appears possible to satisfy the energy needs of the world for long periods of time. Present-day economical use of energy from the fission process is contingent upon fields of operation which include mining, concentration and fuels preparation of uranium and thorium, nuclear reactor operation, recovery and re-use of fuels discharged from nuclear reactors, and utilization of radiation. Successful achievement of economical nuclear energy is also contingent upon developments of materials, components, and controls required in each of these fields. In the United States, developments of nuclear reactor power systems are being conducted simultaneously by a number of different approaches. Each of the reactor concepts have specific applications. A large proportion of developments of nuclear power reactors involves conversion of fission energy to thermal energy in steam, from which electric power can be generated. Since the fission process produces large amounts of heat energy at high temperatures, whose extraction is limited basically by suitable materials of construction and heat transfer, certain developments are underway to achieve a hightemperature nuclear power reactor which has characteristics of high energy output per unit of mass. Since known technology does not permit complete use of reactor fuels in a given power cycle, recovery of the unused portion of fuel, separation of fissionable isotopes, and isolation of fission product wastes are important economic parameters. Research indicates that the products of the fission reaction have potential uses in many diversified fields. Examples are utilization of fission products in processing foods, chemical reactions, ionization sources, plant growth studies, metallurgy, and chemistry. 1

2.0 THE ENERGY RESOURCES OF THE WORLD Life on our planet - Earth - depends upon the energy of the sun. Our civilization is founded upon man's use of energy. Accumulated energy in the form of fuel provides warmth in the winter, prepares our food, produces our metals, provides transportation, provides lighting other than the sun, furnishes energy for our communication devices, and makes possible the tremendous productivity of the individual worker. Our civilization and standard of living depends upon large amounts of low cost fuels. Let us examine the quanitities of energy which are produced by the populous of this world. Table 1 presents the energy output per capita in the United States. Note that in 1850, each man, woman, or child consumed about 1.0 horsepower per ten-hour day. By 1920, the energy output per capita increased about threefold to 30 x 106 BTUs per year. A rapid growth was apparent between 1920 and 1955, rising to the high level of 75 x 106 BTUs per year presently. If the energy output per capita continues at the present level of 3.5 percent per year cumulative, it can be expected by year 2000 that the energy output per capita will approach 450 x 10 BTUs per year. This country leads the world in energy output per capita. TABLE 1 ENERGY OUTPUT PER CAPITA IN THE UNITED STATES Year BTU/Year/Capita 1850 10 x 106 1920 30 x 106 1955 75 x 106 2000 (Estimated) 450 x 106 The energy consumption for the rest of the world at today's population level and standard of living is shown in Table 2. The per capita energy consumption in India for all uses is less than 1 percent of the output in the United States. The energy output per capita in the United Kingdom is less than half of the energy output in the United States. TABLE 2 ENERGY OUTPUT FOR REST OF WORLD FOR YEAR 1955 BTU/Year/Capita India 0.75 x 106 United Kingdom 30 x 106 Germany 60 x 106 Russia 60 x 106 In Germany and Russia, the last 30 years have prompted considerable growth in energy output. It can be noted that their present level is nearly comparable 2

to the energy output per capita in the United States. However in 1930, Germany and Russia were 50 years behind the United States, and they are now increasing their rate greater than the United States. Engineering and scientific advancements in the United States have been successful in producing energy to meet our needs so that we are prone to ignore the problems involved. A consideration of future energy requirements is of such scope and complexity that it should be handled on a world-wide basis. The energy output discussed. in the past tables applies to that energy which is actually used. This value is considerably less than the total amount of energy in fuel which must be produced, or the energy input. The efficiency of utilizing energy has been steadily increasing in the United States. This efficiency has increased from 8 percent to 30 percent in the last 100 years. It is believed that this increased efficiency has been due largely to improvements in home heating devices. If we consider the energy input or consumption of the world, Table 3 indicates that in 1955 the consumption is equal to 0.1 x 1018 BTUs, oftentimes referred to as 0.1 Q. By considering an overall efficiency of utilization equal to 30 percent and a population of 2.4 billion with a per capita output of 70 million BTUs, we arrive in 1955 at a value of 0.1 Q. This is 0.2 of that estimated amount necessary to give the whole world a standard of living equivalent to ours. TABLE 3 ENERGY OF THE WORLD Year BTU/Year "Q" 1955 0.1 x 1018 0.1 2000 1.0 x 1018 1.0 If we consider the population growth simultaneously with the cumulative output demands of energy at about 4 percent per year, it is seen that in year 2000 the energy consumption for the world may lie at around 1 Q. Let us consider the sources of supply for energy. For the past centuries, fossil fuels such as coal, oil, and gas have supplied the major portion of the world's energy requirements. The most reliable estimates indicate that the energy content in coal, oil, and gas that can be recovered at no more than twice present-day costs is less than 40 Q. If mean averages of energy consumption for the next 100 years are assumed to be 0.4 Q per year, then we will have exhausted those supplies of fossil fuels that can be recovered at an economical price within that 100-year period. Table 4, shown on the next page, presents the total possible amounts of energy which can be extracted from various materials. The discovery of nuclear fission has opened. up the prospects of an entirely new source of power. Basic materials that can be used for generating energy from nuclear fission are uranium and thorium. Minerals containing these elements are widely distributed through the earth's crust. 3

TABLE 4 TOTAL POSSIBLE AMOUNTS OF ENERGY WHICH CAN BE EXTRACTED FROM VARIOUS MATERIALS BTU/Pound Tons'Q"1 Coal, oil, and gas* 13,000 15.4 x 1011 40 Uranium and thorium (through fission process) 3.6 x 1010 8 x 106** 624 Water (through fusion process H2 -, He3) 30 x 1010 Unlimited * At cost no more than twice of present-day costs. ** Total available is 1012 tons. The total amount of uranium and thorium in the earth's crust to a depth of three miles is estimated to be 1012 tons. In total quantity, therefore, the tonnage is about equal to the tonnage of coal, oil, and gas which can be exhausted at a reasonable economic level. If technology can be advanced so that uranium and thorium can be extracted from low-grade ores at a cost of about $100 per pound., at this figure the world's reserves would be about 26 million tons. If we assume a conservative viewpoint and state that no more than 8 to 10 million tons of uranium and thorium can be extracted at competitive economics, then it is seen that at this tonnage we would have prolonged our energy requirements at the level of 1 Q per annum for about 6 centuries. It is interesting to note that by employing the fission process, a large amount of energy can be released per unit mass. Upon the complete fission of one pound of uranium, there is liberated about 3 x 1010 BTUs of heat. One pound of fissionable material will produce energy equivalent to that obtained by the combustion of 1400 tons of coal. The ultimate production of energy from the nucleus is not limited to the fission process. Recent. announcements indicate active programs to obtain controllable energy by the fusion of light nuclei. Principally, such fusion reactions which produce large quantities of energy are the hydrogen nuclei combination or the carbon-nitrogen cycle of combination. Theoretically, one can calculate that one pound of water will produce about 3 x 1011 BTUs of energy or about ten times more than one can obtain from one pound of fissioning uranium or thorium.

3.0 FIELDS AND ACTIVITIES INVOLVED IN NUCLEAR ENERGY The achievement of economical enterprises in the fields of nuclear energy is contingent upon the ability of private industry and the Government to successfully develop and apply technology in many fields of activity. Responsibilities for undertaking nuclear energy by American industry are being considered by many organizations. Much of the effort is being concentrated upon the development of economical nuclear power plants in which the economics are dependent upon the costs of materials andl supplies obtained from other fields of activity. To give full consideration to nuclear power producing operations as well as to the immediately related fields, it becomes necessary to consider ranges of activities from mining and basic metallurgy to the disposal of wastes from nuclear reactors. In general, the fields and activities of nuclear energy might be considered in two general categories as follows: 3.1 The production and use of source and fissionable materials. 3.2 The production of materials, supplies, and equipment essential to nuclear reactors and their operations. In Table 5 there are listed fields of operations which directly apply to nuclear reactors. TABLE 5 PRODUCTION AND USE OF SOURCE AND FISSIONABLE MATERIAL 1. Sources of uranium 2. Milling and concentration 3. Feed preparation 4. Isotope separation 5. Fuels preparation 6. Reactors 7. Reactor fuel recovery 8. Fission products and radiochemicals Each of the fields shown in this table are closely interrelated, both from viewpoints of technology and economics. To give consideration to investments or profits from any one of the fields requires good understanding of how that field relates to other phases of the program. In Table 6, shown on the next page, there are listed those operations which indirectly influence production and manufacture from nuclear reactors. With the technology which is known today, each of these fields are special in nature requiring new developments, new engineering applications, and new methods for manufacture. It is not possible to make full contributions to the programs of nuclear energy in any one of these operations withoue unldestanding the technologies required in those activities directly applying to nuclear reactors. 5

TABLE 6 PRODUCTION OF MATERIALS, SUPPLIES, AND EQUIPMENT ESSENTIAL TO NUCLEAR REACTORS 1. Fuel cladding material 2. Coolants and moderators 3. Reflectors 4. Chemical requirements for reactor operation and subsequent processing 5. Mechanical components such as pumps, etc. 6. Instrumentation and control 7. Structural materials By definition, therefore, of the term nuclear energy, we have broadened the aspects from nuclear power reactors to include the many activities that are necessary to make a nuclear reactor chain reaction possible, as well as giving consideration to many by-products that come or may come about as a result of operating a nuclear reactor. In nuclear energy fields, where the fission reaction is the basic mechanism by which energy in many forms can be extracted, there are two basic materials that are essential to programs of nuclear reactors, These are uranium and plutonium. Let us consider the steps which make possible the use of uranium in nuclear reactors. Figure 1 plots successively the chain of eventswhich is essential to utilizing uranium and recovering products therefrom due to influences of the fission mechanism. Uranium ore is found in many forms and states of chemical combinations in the earth's crust. The uranium which is found in these ores contains several isotopes, only two of which are present in concentrations high enough to be of practical importance. These isotopes are uranium-238 and uranium-235. Uranium-235 is the only material existing in nature in sufficiently large quantities which will undergo a self-sustaining fission process. It occurs in uranium ores to the extent of about 0.7 percent of the total uranium content. Pure uranium in its natural state is termed natural uranium. It is noted from Figure 1 that the ores must be mined and concentrated so that a concentrate of uranium oxide or possibly uranium metal is produced. The product from such refining is natural uranium in some chemical form or as metal. One of the routes which can be taken consists in separating the fissionable isotope from the uranium-238. This is done by conversion of the uranium to uranium hexafluoride, which then permits separation of the isotopes by gaseous diffusion methods. The uranium-235 produced is nearly in pure form, and therefore, small compact reactors which may be breeders, fissioning power reactors, or convertors can utilize enrichments of uranium stocks with the isotope, uranium-235. As a result of operating these types of enriched reactors, the spent fuels resulting therefrom contain unfissioned uranium-235, and in the case of breeders or convertors, may actually produce new fissionable isotopes - either uranium-233 or plutonium-239. Thus, the fuel product from such reactors must be subjected to processing and metals conversion. The fissionable materials can be recovered in pure form and reconstituted into reactor fuels to be returned to the reactors or sold elsewhere. The radioactive fission products must be accumulated. If uranium-238 is employed, it 6

FIG. I OVERALL USES OF URANIUM IN NUCLEAR ENERGY URANIUM MINING PURIFICATION. a8. METALS REDUCTION CONVERSION TUL TO UF j U-U35 MAKE - U P HETEROGEOUS REACTORS ISOTOPE SEPARATION CHEMICAL PROCESSING FISSION U-235 U-238 DEPLETED U PLUTONIUM PRODUCTSI [E E.PRODUCTS METALS METALS METALS METALS |REDUCTION REDUCTION REDUCTN REDUCTION BREEDERS POWER CONVERTERS STOCKPILE BE SHIE LDIN BLANKE REACTORS PURPOSES PROCESSING PROCESSING PROCESSING METAL METAL METAL METAL NVERSION CONVERSION CONVERSION CONVERSION FISSO PLUTONIUM U-235 U-238 U-28 PLUTONIUM PLUTONI ~PRODUCTS PRODUCTS ~ ~, I~~1 ~'

can also be recovered and re-used for the production of additional plutonium in breeders and convertors. It is also possible to build nuclear reactors which use natural uranium as fuel. An example of such reactors are those presently in operation at Hanford, Washington. Such uranium reactors are primarily built for the production of plutonium. At the present time, there are no reactors in this country which produce power when using natural uranium as a fuel. The products from such natural uranium reactors are basically depleted uranium, plutonium, and radioactive fission products. The depleted uranium can be re-utilized in the plutonium producing reactors or sold as source materials to other reactors for breeder blankets or materials which can be converted into plutonium. The plutonium produced from natural uranium reactors can undergo a cycle comparable to the isotope,, uranium-235, produced in gaseous diffusion. By employing varying enrichments of plutonium with uranium, it is possible to.build breeder reactors, convertor reactors, and propulsion reactors. The products from each of these reactors must undergo processing and metals conversion to reconstitute the unused portions of the fuel in such form so that they might be re-used in other reactors. Figure 2 indicates the overall use of thorium in nuclear energy. The major source of thorium is monazite sand. Monazites are heavy, dark colored phosphates of the cerium earths. They are found as sands along stream beds or beaches. Principal domestic sources are in Idaho and the Carolinas. Other deposits are found in India, Brazil, Australia, Africa, and Canada. Thorium ores are mined in a conventional manner. The technologies of purification and metals reduction are fairly well established. Probably more is known concerning the metallurgy of thorium than is known of the complete metallurgy of the uranium isotopes. Nuclear reactors of the breeder type or the convertor type can be built to use thorium primarily for the production of the fissionable isotope, uranium-233. In cases of reactors employing thorium, they must be initially started with the fissionable isotope, uranium-235, until a sufficient quantity of uranium-233 has been produced to sustain operation of that reactor at a power level. The fuels from such thoriumx reactors must be subjected to processing, principally for the recovery of protoactinium-233 and uranium-233. The products from such breeder and convertor reactors can be either recycled or re-used or sold or disposed to power fissioning reactors similar to that mentioned for uranium-235. It is to be noted that radioactive fission products are also produced and disposition of such fission products must be made. 8

FIG. 2 OVERALL USES OF THORIUM IN NUCLEAR ENERGY THORIUM MINING PURIFICATION a METALS REDUCTION,.r - U-235 FOR START UP BREEDER CONVERTERS BLANKET PROCESSING Pa-233 U-233 THERMAL POWER BREEDER REACTORS. I PROCESSING METAL CONVERSION FISSION THORIUM U-233 PRODUCTS STORAGE g

4.0 THE FISSION PROCESS Fission occurs when a nucleus of the appropriate type captures a sub-atomic particle called a neutron. The nucleus splits into two lighter nuclei, the primary fission products, and at the same time energy is released. In each act of fission, neutrons are emitted. If one of these neutrons produced for each fissioning atom is captured by another nucleus of an appropriate type, a fission chain reaction with the continuous production of energy becomes possible. The device in which the nuclear fission chain is initiated, maintained, and controlled so that the accompanying energy is released at a specified rate is called a nuclear reactor. It is seen that a neutron balance is therefore necessary to sustain a fission reaction. Since from 2 to 3 neutrons are released per fissioning nuclei capturing a neutron, the loss of neutrons from the system by escape and by capture in various ways which do not lead to fission, determines the critical size for a given system which will sustain a chain reaction. Figure 3 indicates one of the mechanisms by which the nucleus of a uranium-235 atom undergoes fission. FIGURE 3 TEE FISSION OF A TYPICAL URANIUM-235 NUCLEUS FISSION FRAGMENTS 0 _MCTD~EPJT saB35 INCIDENT NEUTRON Ai U235 NUCLEUS Kr97 T PROTON O E~URON. - GAMMA RAY The fissioning nuclei break up in many other ways to produce a variety of fission product nuclides. In order for a fission reaction to be initiated, there is required some energy from an outside source to make the reaction proceed at an appreciable rate. This is similar to the situation with exothermic chemical reactions where heat or light is required to produce the activation energy. 10

In the case of the fission process, the amount of activation energy required depends upon the particular isotope involved. Some nuclei like uranium-233, uranium-235, and plutonium-239 fission readily with the energy available from 1.1 million electron volt neutrons to cause fission. Some of the fission products formed are delayed neutron emitters and are important in reactors since they augment the neutron flux available to prompt fission. Delayed neutron emission by radioactive nuclides occurs when there is a beta decay to yield an intermediate daughter nucleus in a highly excited state. If sufficient excitation is available, the intermediate compound nucleus then decays with the emission of a neutron in a time of the order of 10"15 seconds. We call the original parent nuclide a delayed neutron emitter since the neutron emission is delayed by the decay rate of the beta process which precedes it. Thus, we see that the products from nuclear fission are neutrons, energy, and fission products. Combinations of fission products that result from nuclear fission range from isotope 72 which is zinc to isotope 158 which is samarium. 11

5.0 NUCLEAR REACTOR CLASSIFICATION AND GENERAL NUCLEAR REACTOR SCHEMES 5.1 Basic Parts of a Nuclear Reactor A nuclear reactor is an assembly of parts each of which play key parts in the operation of a fission process. These parts in general control neutron production, heat generated, and radiation safety. The following table lists those components whose functions are fundamental to reactor operation. TABLE 7 BASIC COMPONENTS OF A NUCLEAR REACTOR Reactor fuel U233, U235I Pu239 Moderator H20, D20, Carbon, Be Coolant H20, Sodium, Bismuth, Gases Reflector Carbon, Beryllium, Water Control rods U238, Hafnium, Boron, etc. Neutron shield Water, Bismuth, Lead Gamma, Beta shield Concrete, Lead, Hafnium, Iron, etc. To illustrate this further, Figure 41 presents a basic reactor schematic. The reactor core is shown as a sphere and in symbolized form is shown the fuel, moderator if required, control rods, and coolant for extraction of fission heat. The reactor core can be surrounded by a reflector whose function is to return neutrons into the core, thus minimizing critical mass or the core may be surrounded by a blanket of neutron absorbing material. An example of a blanket would be uranium-238 which produces plutonium by absorbing neutrons or thorium-232 which is converted to uranium-233. To permit safe operation of a reactor, it is necessary to enclose the reactor with shielding material. Such shielding material must absorb any neutrons leaking from the system, and absorb and shield radioactive particles and rays resulting from fission products formed. This radiation is in the form of alpha particles (helium nuclei), beta particles - high-speed electrons, and gamma rays which are very hard x-rays. For nuclear reactors, there are three fissionable fuel materials. Uranium-235 is an isotope of uranium and is found in nature in large enough quantities to permit its separation from the non-fissioning isotopes. Uranium-233 is produced artifically in nuclear reactors by a neutron being absorbed in thorium-232. Plutonium-239 is produced artifically in nuclear reactors by a neutron being absorbed in uranium-238. The fissionable isotope of uranium, uranium-235, comprises about 0.7 percent of the uranium-238 in nature. To design reactors of small size, it is necessary to process natural uranium so that uranium-235 is separated or increased in concentration (enriched). 12

F/G. 4 BASIC REACTOR SCHEMATIC FUEL REACTOR J MODERATOR BLANKET / CORE' CONTROL RODS AND/OR COOLANT REF LECTO RLAN woman a l~NEUTRON AND a~,.. ~ - a, -,.~ - GAMMA RAY ~'.~ ~... SHIELDING MATERIAL -~'~c:,":.~:~...t~ I'-'. FLOOR.~,',~.~ ~,:_~,'c,-%~~.''.~, ~..::,,,; ~~~i~i~r:CFLOO ]-3I~T

5.2 Description of General Nuclear Reactor Schemes Nuclear reactors, together with their attendant auxiliaries, can be considered from one point of view as manufacturing plants. There are three chief products of such a plant; namely, energy which appears initially in the form of radiation and is degraded to heat and may ultimately be converted to electric power; the fissionable materials, uranium-233 or plutonium-239, which are produced by the absorption of neutrons in source material; gross fission products. Two kinds of raw material for these plants are source materials such as uranium-238 and thorium-232 which, upon the absorption of neutrons, become converted to fissionable materials. Other kinds of raw materials are the fissionable materials themselves which may be regarded as the fuels for the manufacturing plant. If one is to consider a nuclear reactor as a part of a manufacturing plant, it is necessary to consider sources of raw materials, the operation of the reactor and its auxiliaries, and markets for the products of the manufacturing plant. The sequence of interdependent operations upon which the nuclear manufacturing would be based are the following: 5.2.1 The preparation of feed materials, which are the source and fissionable isotopes required for the operation of a reactor. 5.2.2 The enrichment of naturally occurring uranium by means of gaseous diffusion to uranium-235 concentrations sufficiently great that it may serve as a fuel for a reactor. 5.2.3 The formulation of source and fissionable materials into physical and chemical states suitable for use as nuclear fuels. 5.2.4 The operation of a nuclear reactor. 5.2.5 The conversion of the energy from the fission reaction to electricity or to heat for other purposes. 5.2.6 The chemical or physical separation of irradiated fuel to permit the recycling of unused source and fissionable material for further use as fuels. 5.2.7 The processing of separated fission products with the production of packaged gross fission products or the isolation and packaging of selected individual products. In Figure 5, a hypothetical scheme is shown which would permit conducting the operations just described. According to this scheme, natural uranium containing 0.71 percent of the fissionable isotope uranium-235 is the raw material input to an enrichment plant. Partial enrichment of the fuel would occur, resulting in the production of two streams from the isotope separation plant. The enriched stream contains 1 percent of uranium-235 and 14

FIG. 5 SPENT FUEL GRAMS/DAY % REACTOR FUEL U-235 23 0.11 GRAMS/DAY % U-238 20,250 208 1.0 Pu 127 0.61 20,592 F. P. 400 1.92 20,800 20,800 NATURAL U GRAMS/DAY % U-235 219 0.71 / \ REACTOR U-238 30,581 30,800 ISOTOPE HEAT | 400MW SEP'N PLANT POWER PLANT 25% EFF'Y DEPLETED U GRAMS/DAY % U-235 1 I 0.11 POWER 100 MW U-2:8 9,989 10,000 ENRICHED URANIUM REACTOR SYSTEM WITH ENRICHMENT PLANT PRODUCTS: POWER ENRICHED URANIUM PLUTONIUM DEPLETED URANIUM RADIOCHEMICALS 15

the depleted streams 0.11 percent. The enrichment of the fissionable isotope from 0.71 percent to 1 percent in concentration imparts to the enriched fuel a sufficient reactivity in excess of that occurring in natural uranium to permit certain additional latitude in reactor design and operation. The products of the reactor described in this system will be plutonium, fission products, and power. The production of power from heat is assumed to be straightforward, and it is assumed in this operation that the steam turbine and generating equipment have an overall efficiency of 25 percent based upon the incoming heat. The spent fuel discharged from the reactor contains a residual 0.11 percent of uranium-235 and 0.61 percent of plutonium. The total of these is 0.72 percent, which is not as great as the 1 percent of uranium-235 which entered the reactor. Consequently this type of reactor does not produce as much fissionable plutonium as it burns uranium-235. The operation of this type of system depends upon the availability of an isotopic separation plant, since the uranium-235 which is produced is consumed without the production of corresponding quantities of plutonium. The plutonium itself might be used as a fuel for recycling through the reactor if it were produced in quantities sufficient to replace the uranium-235 originally charged. The depleted uranium which is produced by the isotope separation plant is a by-product of this system. An alternative scheme, calling for the operation of a reactor with natural uranium raw material, is given in Figure 6. In this scheme, natural uranium is mixed with plutonium from previous reactor operations. Plutonium might have been produced previously in some reactor employing a cycle using no recycle plutonium, such as that described in Figure 5. Once a supply of plutonium is available, it can be used to enrich the incoming natural uranium with fissionable plutonium instead of adopting the expedient described in Figure 5 of conducting an isotopic separation upon a natural uranium in order to increase the content of fissionable uranium-235. During operation of the reactor of Figure 6, the plutonium and uranium-235 which are charged undergo fission releasing neutrons which are absorbed in uranium-238 and thereby producing more plutonium. Some of the plutonium thus produced fissions in turn and produces more power and more plutonium. This sequence of events may be continued until the presence of fission product poisons necessitates the removal of the fuel because of declining reactivity. At the conclusion of this reactor cycle, there remain a total of 95 grams of fissionable material compared with the 190 grams which were charged to the reactor. Consequently, a system of this kind requires the continual charging of fresh natural uranium, and hence, causes a gradual depletion of the stock of fissionable uranium-235. However, if the reactor described here were to operate as shown, no net depletion of the original charge of plutonium would occur. The products from such a system would be power, plutonium to sustain reactor operations, and radiochemicals. Figure 7 describes a scheme for self-sustaining nuclear manufacturing system. This system produces slightly more fissionable material than it consumes, and differs in this respect from the systems described in Figures 5 and 6. Consequently, the only raw material required is uranium-238. The uranium-238 16

PLUTONIUM SPENT FUEL 90 GRAMS/DAY GRAMS/DAY % U-235 5 0.04 U-238 13:,705 PU 90 0.64 F.P. 400 2.81 14,200 REACTOR FUEL CHEMICAL REACTOR _ SEPARATION PLANT HEAT, 400 MW REACTOR WASTE POWER PLANT 25% EFF'Y POWER S 100 MW NATURAL U GRAMS/DAY % U-235 100 0.71 U-238 14,01 0 FIG. 6 14,110 PLUTONIUM RECYCLE REACTOR SYSTEM USING NATURAL URANIUM FUEL PRODUCTS: POWER PLUTONIUM RADIO CHEMICALS 17

PLUTO-NIUM 401.4 GRAMS/DAY U-23' 39703 GRAMS/DAY U-238 U-238 REACTOR PU BLANKET BLANKET 400 40,103 GRAM SEP. PLANT GRAMS DAY DAY NEUTRONS 1.4 GRAMS/DAY FhSSION PRODUCTS 400 GRAMS/DAY REACTOR CORE PU 2%FP._ PU GRCORE SEP. PLANT 20,000 GRAMS/ HEAT 400 MW POWER PLANT 25% EFF'Y POWER 100 MW FIG.' 7 FAST PLUTONIUM U-238.REEDER REACTOR SYSTEM PR ODU CTS: POWER PLUTONIUM R ADIO CHE M IC A LS 18

could be taken in the form of depleted uranium from the operations of an isotope separation (diffusion) plant such as that described in Figure 5, or from the discharged fuel from a reactor such as that of Figure 6. The scheme shown in Figure 7 is a uranium-238 - plutonium fast breeder reactor. This scheme is more complicated than either of the previous reactor systems described. Most of the fission occurs in the reactor core. Neutrons escaping from the surface of the core are absorbed in the surrounding blanket of uranium-238 instead of being allowed to escape as in the previously described systems. The capture of these neutrons accounts in large part for the fact that more fissionable material is produced than is consumed in this type of system. The course of operations is that uranium238 is brought into the system and mixed with recycled uranium-238 from the blanket separation plant. This mixture is then fed through the blanket whereupon absorbing neutrons, some of the uranium-238 is converted to plutonium. This plutonium is removed upon subsequent separation. Some of this plutonium may be mixed with plutonium separated from previous core operations and fed to the core as fuel. After undergoing the reaction of fission in the core, the plutonium fuel is again subjected to the separations process to remove the fission products, and is recycled for more burn-up. Again it is considered that the operation of the power plant is of a conventional nature and is not further described here. The raw material upon which this type of plant operates is naturally occurring uranium or depleted uranium-238, and the products are power, plutonium, and radiochemicals. B3ecause cons;truction of this type of reactor system is more complex than those of Figures 5 and 6, the capital and operating costs may be greater. This fact may offset to some extent the economic attractiveness of producing more fissionable material than is consumed. In Figure 8, an alternative reactor scheme is shown which is known as a uranium-233 - thorium thermal breeder reactor system. The raw material to the system is thorium-232. This is mixed with a certain amount of thorium232 containing uranium-233 produced in previous reactor operations, and is charged to the reactor. During reactor operations the reaction of fission occurs and excess neutrons are absorbed in the thorium-232 rather than in uranium-238 as in the previously described reactor systems. During startup operations, it will probably be necessary to use uranium-235 as a fissioning fuel in order to initiate the cycle. After the reaction of fission and absorption of neutrons has occurred, the fuel is sent to the chemical separation plant, where fission products are removed and stored or sold. The decontaminated fuel contains uranium-233. The uranium-233 and thorium-232 output from this separation plant can then by recycled to the reactor for further conversion and power production. If uranium-233 were produced in excess of recycle requirements,the surplus would be a product of operations. The raw material required for this sytem is thorium232, which occurs in nature. The products are power, uranium-233, and radiochemicals. It is not known for certain however that the thermal thorium-uranium-233 breeding cycle is self-maintaining without the occasional addition of small amounts of uranium-235. 19

SPENT FUEL G R AM S/DAY F. P. 400 REACTOR FEED U-233 208 TH 20,192 GRAMS/DAY, 20,800 U- 233 208 (1%) TH 20 92 9 2 CHEMICAL REACTO R s"SEPARATION PLANT THOR IUM 400 GRAMS/DAY FISSION PRODUCTS 400 GRAMS/DAY HEAT i 400 MW POWER PLANT 25% EFF'Y FIG. 8 THERMAL U-2;33 THORIUM BREEDER REACTOR SYSTEM POWER 100 MW PRODUCTS: POWER U-233 RADIOCHEMICALS 20

The choice of the system to be employed is governed as in the case of other types of manufacturing plants by many considerations not necessarily related to the technical feasibility of the operation. Among these considerations are availability and cost of raw materials, such as natural uranium and natural thorium, uranium isotopically enriched in uranium-235, plutonium, structural materials, coolants, moderators, the cost of operating the separation plant and many other factors which can be determined only through a detailed technical and economic analysis. It is thought that the development of breeder reactors will be a necessary part of a nuclear manufacturing economy. This will be the case if full advantage is to be taken of our natural resources of uranium. Since most of natural uranium is in the form of uranium-238, the use of breeder reactors should produce supplies of fissionable material n excess of those used. Such convertor reactors for power production may be used in applications where a less complicated type of reactor installation is desirable. 5.3 Reactor Classification Based on Neutron Energies The fission cross section for natural uranium is about one barn for neutrons with energies in the neighborhood of 1 mev. For thermal neutrons, however, the fission cross section for uranium-235 is 549 barns, and so it may be advantageous to have thermal neutrons available to cause new fissions. Since the neutrons produced by the fission process have average energies of about 1 mev, they must be slowed down by substances called moderators to thermal energies in order to take advantage of the high thermal neutron fission cross sections of uraniumw-235 and plutonium-239. Moderator nuclei slow neutrons by absorbing their energies in recoils from elastic collisions. A good moderator has a small neutron caputre cross section and a small mass number A. Reactors using thermal neuttrons to cause fission are called thermal reactors, and those using fast neutrons (no moderator used) are called fast reactors. 5.4 Reactor Classification Based on Fuel Distribution Reactors may be further classified according to the distribution of fuel. If the fuel is distributed uniformly as in the case of an aqueous solution of uranium salt or a molten solution of uranium metal in another metal, the reactor is called a homogeneous reactor. If on the other hand, the fuel is lumped into fuel elements separated from one another by the moderator or some other substance, we have a heterogeneous reactor. Some possible types of power reactors are listed in Table 8. 5.5 Reflectors and Blankets In order to reduce the escape of neutrons from a reactor, a reflector is used. The reflector action is diffuse reflection and is due to the neutrons being elastically scattered by the nuclei of the reflector material back into the reactor core. Good reflector materials have large neutron 21

TABLE -8 SOME POSSIBLE TYPES OF POWER REACTORS* Overall Fissile Source Gain Recycling System Material Material Tye Factor Material of Fuel Product Remarks i U235 U238 Thermal Negative Natural U No Large U requirement. 2 U235 U238 Thermal Negative Natural or Yes Pu U235 separation plant needed convertor enriched U for recycling to save U. 3 U235 Th Thermal Negative U235 & Th Yes U233 Separation plant needed for convertor U235 with feed of natural U. 4 U233 Th Thermal Negative or Th & U233 (?) Yes May be self-maintaining. If breeder zero (?) not, feed of U233 is required from system 3, 6, or 8. 5 Pu U238 Thermal Negative Pu & Yes Pu could be supplied by breeder depleted U system 2, 7, or 8. 6 U233 Th Fast Positive (?) Th Yes U233 May breed U233, which could breeder or zero be used to supply system 3. 7 Pu U238 Fast Positive Depleted U Yes Pu Could produce U233 if blanket breeder material was Th. 8 U235 U238 or Fast Positive U235 & U238 Yes Pu or Separation plant needed for Th convertor or U235 & Th u233 U235 with feed of natural U. * C. A. Rennie, Chem. g. Progress Symosium Series, Vol. 50, No. 12, 1954, Amer. Inst. of Chem. Eng., p. 222.

scattering cross sections and small capture cross sections. Very pure graphite is often used. A beam of neutrons incident on a 15-inch thick slab of graphite is 90 percent diffusely reflected, i.e., the slab has an albedo of 0.90. Sometimes a natural uranium blanket surrounds the reactor core to capture neutrons which would otherwise be lost. Capture by uranium-238 yields uranium-239 which decays by two beta emissions to plutonium-239. In this way, fissionable plutonium-239 may be made from non-fissionable uranium-238. Similarly, a thorium blanket can be used to produce uranium-233 which is fissionable. This is referred to as fuel breeding.

6.0 INTEGRATED NUCLEAR REACTOR SYSTEMS 6.1 Introduction Within the next ten years, there are reported investments approaching $800,000,000 for programs to develop economical nuclear power plants by government and private industries. In the field of nuclear reactors, there are a number of different approaches to reactor concepts being pursued simultaneously. The U. S. Atomic Energy Commission have established a five-year program financed by the government to the extent of over $200,000,000 for major projects of five different approaches to industrial nuclear power. These government financed plants are tabulated in Table 9. In addition to the programs totally financed and operated by the Atomic Energy Commission, government and industry have proposed the construction of five full scale power producing reactors. These power demonstration reactors are presented in Table 10. Of the five listed in the table, Consolidated Edison has proposed to finance their power reactor completely with private capital. Weinberg" points out that with our present state of technology, no one line of reactor development has yet given convincing evidence of superior promise. Also, the objectives of certain reactor installations are widely different from others. Certain reactor installations have as their general main objectives the production of power in the form of electrical energy. In the future, there lies potentialities for using reactors for utilizing thermal and radiation energy for chemical reaction, petroleum refining, etc., as well as producing steam for process and electricity for power and lighting. In earlier discussions, there was indicated that in nature we have two raw materials —uranium and thorium. Thus, it is desirable to pursue avenues for utilizing both of these raw materials. The Atomic Energy Commission' have pointed out possibilities for breeding in thermal reactors when using thorium. Breeding can be achieved when using uranium only when neutron energies are in the "fast" range. Preservation and conservation of energy sources lies partially in successful and economical demonstration of "breeder" reactors. Let us consider how these approaches might be integrated. Figure 9 indicates one plausible method for integration. This method might be termed the "Sun-Satellite" approach to a competitive economy of nuclear production (a large central nuclear production plant of which a "breeder" reactor is the basic component). In this plant, there would be facilities for: 6.1.1 Treatment and processing of uranium and thorium. 6.1.2 Fuels preparation and recovery. Scientific American, vol. 191, no. 6, page 33, December, 1954. 24

TABLE 9 AEC FIVE YEAR REACTOR PROGRAM - GOVERNMENT FINANCED Major Projects of Five Approaches to Industrial Nuclear Power Power Millions Plant Developer Heat Electrical Cost Pressurized Water Reactor Westinghouse 264,000 KW 60,000 KW $85 Experimental Boiling Water Reactor Argonne 20,000 5 000 17 Sodium Reactor Experiment North American 20,000 none 10 Experimental Breeder Reactor No. 2 Argonne 62,500 15,000 40 Homogeneous Reactor Experimental No. 2 Oak Ridge 3,000 yes Homogeneous Thorium 47 Reactor Oak Ridge 65,000 16,000 Note: Preliminary Data and Estimated Costs for Research and Development, Operation and Construction; Fiscal Years 1954-59, inclusive. (Both tables courtesy of Atomic Power Development Associates, Inc.) TABLE 10 ABC POWER DEMONSTRATION REACTOR PROGRAM Public and Private Proposals Approximate Cost Estimated Power Millions of Completion Plant Developer Electrical Dollars Date Pressurized Late Water Yankee Atomic Power 100,000 KW 25 1957 Boiling Water Nuclear Power Group 180,000 47 1960 Sodium Consumers Public Power Graphite of Nebraska 75,000 24 1959 Fast Breeder Consumers, Philadelphia, Electric, Detroit Edison and others lQ0, 000 54 1959 Pressurized * Water Consolidated Edison 250,000 55 1959 Totals 705,000 205 Completely privately-financed, not a part of the Reactor Demonstration Program. 25

URANIUM THORIUM ) HIGH PRESSURE STEAM CONCENTRATE CONCENTRATE POWER P P RODUCT S OUT RAW CHEMICALS IN FUELS PREPARATION POWER BREEDER RADIOCHEMICA L S RAW MATER I AL S RAW MATERIALS AND RECOVERY REACTOR PRODUCTION ~. I + I 1 + 1 I FRESH U OR Th NEW FUEL FISSION PRODUCTS RADIATION RETURNED SPENT FUEL SPENT FUELS S I I < + E- r * FUEL (FRESH) CONVERTOR REACTOR FPOWER ISSIONING REACTOR POWER MOBILE PROPULSION I) POWER PRODUCTION I) PACKAGED POWER PRODUCTS I)'LAND 2) MANUFACTURING PRODUCTS 2) MANUFACTURING 2) SEA ENERGY FRESEARCH 8 3) RESEARCH 3DEVELOPILT 3) AIR FIG. 9 A POSSIBLE INTEGRATION OF NUCLEAR INDUSTRIES

6.1.3 Breeder-reactor. 6.1.4 Radiochemical production. This central nuclear production plant could be designed to produce power, steam, manufacture chemicaLs or petroleum products, radiochemicals and radiation shources. It could be a prime producer of fissionable materials for the satellites associated with it. Such a breeder could start with U-235 from gaseous diffusion or purchase plutonium for starting fuel. When excess fuel through "breeding" becomes available, such fissionable materials could be prepared for sale, license or use to converter reactors, fissioning reactors and mobile propulsion reactors. The spent or depleted fuels from the satellites could be returned to the "sun" system for recovery of U-235, Pu-239, radiochemicals, uranium and thorium. Thus a self-sustaining economy can be achieved. Another approach is to assume that each reactor system considered is capable of a self-sustaining economy. This is likely the case for many major industries in the country. A self-sustaining nuclear manufacturing plant could also produce chemical products from the energy generated in fission, as well as selling fissionable fuels, and radiochemicals. With the vision of competitive economics by private industry in the nuclear field, let us consider certain specific reactor systems. 6.2 Discussion of Reactor Systems A number of organizations have spent much time and effort to evaluate technical and economic feasibilities of nuclear reactor systems. General objectives of these groups were: 6.2.1 Whether any known reactor systems can be shown to be technically and economically Ieasible to compete with present methods for power generation. 6.2.2 Whether sufficient technology exists today to begin construction of industrial plants. 6.2.3 The projected possibilities of different reactor systems. Survey studies conclude that nuclear reactor technology has progressed to a stage where it is technically feasible to construct and operate a nuclear reactor for central station power generation. The findings indicate that no reactor system can yet produce power economically. *Nuclear Power Reactors, A Report to the USAEC, by Nuclear Power Project Staff of Foster Wheeler and Pioneer, March, 1955. 27

Similar studies conducted by the faculty and staff of the University of Michigan+ indicate technical feasibility for nuclear powered merchant ships. This study indicates that economics can be achieved only through an aggressive program of development, engineering, construction and operation. With these viewpoints in mind, let us consider some of the systems which are either in operation or in some stage of development and engineering. 6.2.4 Pressurized Water System with Heat Exchanger Pressurized water reactors are the first type to achieve operations of proven nature. The submarine thermal reactor —the Nautilus —is of this type. Pressurized water reactor systems are of the heterogeneous type operating in the thermal range of neutron energies. They may be highly enriched with U-235, or partially enriched with U-235 in U-238. If natural uranium were to be used as fuel, heavy water would be required as a moderator in place of light water. The reactor fuel is composed of solid fuel elements. For highly enriched reactors, it is necessary to design the fuels for the specific power so that extended surfaces for heat transfer are provided. Fuel elements of the plate type are common for highly enriched reactors. The plates are of the sandwich type. The "meat" of the "sandwich" is the active fuel —either pure or diluted with an inert material. The "bread" or cladding is a metal such as zirconium or stainless steel. Figure 10 indicates the basic components of a closed loop circulating water heterogeneous reactor. Water at high pressure —2000 psig — at temperatures approaching saturation is circulated by means of a pump through a high pressure vessel in which the reactor fuel is located. The thermal fission energy is removed by the circulating water. The circulating water flows through a heat exchanger which serves as a steam generator. Feed water is transferred to the heat exchanger, steam is vaporized. Steam conditions may approach 600 psig saturated steam. The steam flows to a turbine generating electrical power. Control of the reactor is sustained by positioning control rods which serve as poisons absorbing neutrons. Table 11 presents data on the pressurized circulating water reactors for propulsion. The PWR is a pressurized water reactor designed by Westinghouse Electric Corporation for the Duquesne Light Company of Pittsburgh. This reactor uses partial enrichment of natural uranium as fuel. The core of the PRI will generate about 300 megawatts of reactor heat which will be transferred to a heat exchanger by circulating Folsom, R. G., et al., "NTuclear Propulsion of Merchant Ships - An Engineering Summary," 2362-2-F, University of Michigan, June 1, 1955. 28

rl~coNTRoL ROs TO~~~~~~~~~~~~~~~~~~~~~~~~~~~~ STA TOSTA DRMHETH TDU [ f h',, COR ~~~~~~~~~~~~~~~~~~~~~I DRUM "H~~~~~~EACTOR FEED WATERIN' — D WATERI PUMP~OR DRUMP IEXCHANG ~ ~ SHERLILD: C HNE FIG. lo P ESSRZDWTRRACTOR (POWER LEVEL 100 ME."WATTS)~~~~~~~~~~~~~~~~~~~~

TABLE 1l DATA ON REACTOR TYPE Heterogeneous, Water Cooled GENERAL Name STR reactor Purpose Mobile power Neutron Energy Thermal Status In operation for over 1 year MATERIALS Fuel Enrichment U-235 Fuel Elements Sandwich plates U, Zr Fuel Element Jacket Zr Moderator H20, high pressure Reflector H2., high pressure Primary Coolant H20, high pressure FUEL Maximum Temperature in Fuel Element 645 Sheath Temperature OF 551 Average Cycle Time 600 hours Percent Burnup per Cycle LIMITATIONS Reactor temperature limited by pressure required to prevent boiling, high pressure vessels, piping and heat exchangers required, steam generated at relatively loaw pressure, high coolant pumping cost. Expensive fuel element. ADVANTAGES Reactor has relatively few hazards, has been proven in service, expensive moderator not used. 3o

water at 2000 psig at a temperature of 5250F. The heat exchanger will produce saturated steam at 600 psig. The steam will flow to a conventional turbine which is expected to generate a net electrical output of 60,000 kilowatts. A second type employing circulating water for the removal of reactor heat for power is a modification of the materials testing reactor developed by Oak Ridge. This power produced has substituted 1U02 - stainless steel plate elements. Table 12 presents data on this type of reactor. 6.2.5 "Boiling Water" Reactor A modification of the circulating water type of heterogeneous reactor is the "flashing" or boiling water type. This type is illustrated in Figure 11. Recent developments have overcome some of the problems and resolved certain unknowns. For application of this principle to packaged power in remote locations, high enrichment is favored when considering this type for large central stations. Where plutonium production is of value, partial enrichment appears desirable. Data for the partially enriched type is given in Table 13 The Nuclear Power Group is proposing the construction of this general type for generation of 180,000 KW of electrical power. Table 14 presents another type of heterogeneous water reactor. It is to be noted that this development considers supercritical water at pressures approaching 5000 psig. Such a reactor is very compact and has no phase change of the working fluid. 6.2.6 Aqueous Homogeneous Reactor Developments by OaJk Ridge have pursued intensively a program for aqueous homogeneous reactors. In a homogeneous reactor, the fuel uranium or thorium is dissolved in an acid solution of water, forming a salt-uranyl sulfate. The solution is transferred to a critical geometry in which fission takes place. From the reactor, the solution flows to a heat exchanger where the heat is transferred to a second loop generating steam. Thus, non-radioactive steam is generated. It is possible to think of a homogeneous reactor which directly boils water from the reactor. Such a system, however, necessitates shielded turbines. (See Figure 12) Table 15 presents pertinent data for the homogeneous reactor experiment. The aqueous homogeneous reactor has interesting possibilities for a small, compact packaged power plant, as a converter reactor for production of plutonium and large amounts of power, and as a thermal breeder when using a thorium U-233 fuel cycle. 31

TABLE 12 DATA ON REACTOR TYPE Heterogeneous GENERAL Name MTR type power producer Purpose Power production Neutron Energy Thermal Status Preliminary design and feasibility study MATERIALS Fuel Enrichment U02 Fuel Elements Plates, flat, rectangular Fuel Element Jacket Stainless steel 347 type, UO2 SS Moderator H20 Reflector H20 Primary Coolant H20 high pressure FUEL Maximum Temperature in Fuel Element 575 Sheath Temperature OF 525 Average Cycle Time 9 months LIMITATIONS Reactor temperature limited by pressure required to prevent boiling, high pressure vessels, piping and heat exchangers required, steam generated at relatively low pressure, high coolant pumping cost. Relatively inexpensive fuel element not yet proven. ADVANTAGES Expensive moderator not required, relatively few hazards. 32

CONTROL RODS SHIELD BOUNDRY BUS BARS DRUM I L i DRIPS TO CONDENSER, STEAM.SJ BLEEDS a_ _SHIELD ROUNDRY FIG. 11SCHEMATIC OF BOILING WATER REACTOR

TABLE 13 DATA ON REACTOR TYPE Boiling Water Cooled GENERAL Name Boiling reactor for heat and power production Purpose Power and heat for remote locations Neutron Energy Thermal Status Preliminary design and feasibility study MATERIAL Fuel Enrichment Zr, U slightly enriched Fuel Elements Plates, flat, rectangular Fuel Element Jacket Zr Moderator H20 Reflector H20 Primary Coolant H20, boiling FUEL Maximum Temperature in Fuel Element -- Sheath Temperature OF Above steam temperature of 4860F Average Cycle Time 12 months LIMITATIONS Turbine and auxiliaries are radioactive, lower heat flux in core than with pressurized water reactor, high rate of water circulation required, possible effects of motion on the operation of the reactor, expensive fuel element, not yet proven. ADVANTAGES Heat exchangers and primary coolant circulating pumps not required, reactor is inherently self-regulating, availability of higher steam pressures than with pressurized water reactors.

TABLE 14 DATA ON REACTOR TYPE Heterogeneous GENERAL Name Supercritical water reactor Purpose Mobile Power Neutron Energy Intermediate Status Design and Development MATERIALS Fuel Enrichment U02 dispersed in stainless steel matrix Fuel Elements Plates 1" square box with parallel plates and sine wave fillers Fuel Element Jacket Type 347 stainless steel.007" thick Moderator H20 Reflector 120 Primary Coolant H20, high pressure (about 5000 psi) FUEL Maximum Temperature in Fuel Element 1300 Sheath Temperature OF Not determined Average Cycle Time 144 hours LIMITATIONS Materials for high pressure and temperature service a problem, retaining mechanical seals, etc., at high pressure and temperature. Reactor not proven. ADVANTAGES High pressure steam with resultant good cycle efficiency, small size of reactor, no phase change in reactor.

BUS BARS SHIELDING STEAM DRUM ~~~~~~~~~~~~~~~~~~~~~~~~~~~II TURBO-GENERATOR I~~~~~~~~~~~~~~~~~~~~~~~~~~ I ~. HEAT EXC HANGER HOMOGENEOUSEXHNR CONDENSER REACTO I CY, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~II!', FEED WATER I ~~~~~~~~~~~HEATER PUMP L- ooNs R CIRCULATING I OND E PUMP FIG. 12 SCHEMATIC OF AQUEOUS HOMOGENEOUS REACTOR SYSTEM

TABLE 15 DATA ON REACTOR TYPE Homogeneous Fuel (Aqueous) GENERAL Name Homogeneous reactor experiment (HRE) Purpose Experimental Neutron Energy Thermal Status Operation MATERIALS Fuel Enrichment U02SO4 Fuel Elements H20 solution Fuel Element Jacket Stainless steel tank Moderator H20 Reflector D O Primary Coolant Circulating fuel solution secondary coolant boiling H20 FUEL Maximum Temperature in Fuel Element 482 out, 467 into reactor Average Cycle Time Time in core, 7 seconds LIMITATIONS Corrosiveness of uranyl sulfate solutions, evolution of radioactive gas, dissociation of water, highly radioactive solution in heat exchangers. D20 high cost item. ADVANTAGES High burnup a possibility, continuous fission product removal a possibility, mechanically simple, reactor is stable, refueling would be simple.

6.2.7 Liquid Metal Reactors In principle there are two general types of liquid metal reactors — heterogeneous and homogeneous. Liquid metal reactors may be highly enriched compact reactors for propulsion and packaged power generation. They may be partially enriched converter reactors, or the core blanket type for "fast" breeding. 6.2.7.1 Heterogeneous-Liquid-Metal Reactor The general principle for heterogeneous molten metal reactors are given in Figure 13. Liquid metal which may be sodium-lithium, sodium-potassium eutectics, or molten salts of metals is circulated through a reactor vessel containing a critical core of heterogeneous fuel. The circulating molten metal removes the fission heat and circulates through a steam generating heat exchanger. Oftentimes, it is considered advisable to interchange the heat between radioactive molten metal with non-radioactive molten metal in the form of an added loop to assure that steam generated will be "cold." The data for the fissioning type of molten metal reactor is given in Table 16. This type is of particular interest to mobile reactors. From the viewpoint of producing sizeable quantities of power and fissionable materials, molten metal reactors are of particular interest since they are capable of "breeding." The first successful work in this direction was the development of Argonne National Laboratories' experimental breeder reactor. This reactor has a small core of either U-235 or Pu-239 surrounded by a breeder blanket of natural or depleted U-238. The core contains no moderating material because in order to breed, it is essential to maintain the neutrons in the fast energy spectrum. The Atomic Power Development Associates, Inc.,9 have proposed development of a fast neutron breeder reactor. The reactor core is an assembly of partially enriched uranium alloy rods. Surrounding the core is a breeder blanket. Plutonium is produced in the core fuel as well as in the blanket. The flow sheet for this fast breeder is presented in Figure 14. (Courtesy of Atomic Power Development Associates, Inc.) *Atomic Power Development Associates, Inc., "Unclassified Description of Proposed Developmental Fast Neutron Breeder Reactor," APDA-104- April 8, 1955.

CONTROL RODS I BUS BARS LIQUI MSHIELD T URBO- GENERATOR <I I I LIQUID METAL SATURATED STEAM CONDENSER VACUUM I SYSTEM I CORE I).__ I I I I I _ I BLEEDS GENERATOR R F EED ELECTRO- MAGNETIC TO PUMP COND. _I I FIG. 13 SCHEMATIC OF MOLTEN METAL PUMED WTER COOLED REACTOR

TABLE 16 DATA ON REACTOR TYPE Liquid Metal Cooled GENERAL Name SIR Purpose Mobile power Neutron Energy Intermediate Status Design and construction MATERIALS Fuel Enrichment U02 Fuel Elements Stainless steel tubes Fuel Element Jacket Stainless steel tube Moderator Be Reflector Be Primary Coolant Na FUEL + Maximum Temperature in Fuel Element 1700 - 300 Sheath Temperature OF 900 maximum Average Cycle Time 900 hours LIMITATIONS Coolant becomes radioactive, heat exchanger requires heavy shield. Be moderator is expensive, Na reacts explosively with water, fuel element removal is a problem. ADVANTAGES High reactor temperature and temperature difference possible, low pressure in primary loop, somewhat higher thermal efficiency. 40

CONDENSATE NoK EXPANSION TANK STEAM STORAGE TANKS <-a * GENERATOR 2. EMERGENCY COOLING CONTROL GECERATON S INTERMEDIATEST HEAT EXCHANGER EMERGENCY COOLING STEAM RELIEF VALVE;0SDIUMP 0 TIwXInTURBINE- GENERATOR UNIT -Pump JF 1 DESUPERHEATER _,,L I A 1 I. t TURBINE STOP VALVE NoK PUMP = PRESSURE-TEMPERATURE NaK DUMP TANK WATER DUMP REDUCING STATION (SAFETY SYSTEM ) TANKBI (SAFETYV TANKODIUM~~~~~~~~~~~~~~~ J~~_~ t CODECONDENSER REACTOR E......... CONDENSER 2 | 5;TOP CHKOT VALVE m EAM STEAM DUMP CONTROL 6 SYSTER RODL SIS CE 14 SURGE:If WALIQUID AND STE SYSTES (S T (Courtesy of Atorriic Power DevelPopment Associates, Inc. ), DE AERATING "-D- G AT ATE V' LV' FEEDWATER G GLOBE VALVE, ~- ~FEEDWATER HTR. HTR. EC,A- STOP CHECK VALVE FIGIE 14 LIQUID 1,ET.AL AND STEA14 SYSTEMS (SCHEIATIC) (Courtesy of Atomic _Powrer Development Associates, Inc.)

Heat is removed from the reactor core and blanket by circulating sodium. The heat is transferred to an intermediate loop of circulating sodium-potassium. (NaK). Through exchange with the intermediate loop, steam is generated in a once-through type of steam generator. Conventional equipment is used thereafter. An elevation of the proposed fast breeder is shown in Figure 15. The reactor and all equipment containing radioactive material are contained in a steel cylindrical building. Other buildings proposed are of conventional design. Compartment shielding is proposed so that flexibility in the location of systems components might be achieved. Technical data released by APDA is presented in Table 17 at the top of the following page. 6.2.7.2 Liquid Metal Homogeneous Reactor A promising high-temperature reactor developed by the Brookhaven National Laboratories offers promise for the production of energy for many uses. The concept offers promise as a fissioning reactor for generation of power at high levels of energy in a small, compact unit. It possesses characteristics for production of U-235 from thorium as a "breeder"' —power generated. It offers potentialities for providing energy at desired levels for chemical reaction. Coupled with closed-cycle gas turbines, it offers promise of a highly efficient, compact, mobile power unit. The general flow system is given in Figure 16. This indicates a bismuth-uranium solution for the core. The solution is circulated continuously through critical geometry where fission takes place. The heat exchanger, an inherent part of the loop, provides means for generation of steam; heat transfer to a closed-cycle gas loop; and means by which radiation and thermal energy can be utilized for endothermic reactions. By surrounding the core with a thorium-bismuth slurry, circulating, the system offers promise as a simple breeder. Technical data available for this reactor development are presented in Table 18. 42

TABLE 17 TECHNICAL DATA TABULATION* Plant Capacity Gross electric capacity - mw 100 Net electric capacity - mw 90 Turbine-generator rating - kw 100,000 Reactor Specifications Power (heat) - kw 300,000 Core diameter - t 3 Core length - ft 3 Overall height of reactor vessel - ft 14 Outside diameter of reactor vessel - ft 10 Thickness of reactor vessel - in 1.5 Core sodium flow rate - lb/hr 11.22 x Sodium velocity - ft/sec 27.6 Liquid Metals and Steam Systems Net thermal efficiency - % 30.0 Sodium temperatures - F Leaving reactor 800 Entering reactor 550 Sodium flow - lb/hr 13.2 x 106 NaK temperatures - F Entering boiler 750 Leaving boiler 500 NaK flow - lb/hr 16.1 x 10 Steam pressure - pisg 600 Steam temperature - F 730 Feedwater temperature - F 400 Steam flow - lb/hr 1 x 106 6.2.7.3 Closed-Cycle Gas Cooled Reactor The U. S. Atomic Energy Commission, American Turbine Corporation **and others have considered closed and opencycle gas turbines in conjunction with a reactor system. An example of such a system is indicated schematically in Figure 17. *Extracted from Atomic Power Development Associates, Inc., "Unclalssified Description of Proposed Fast Neutron Breeder Reactor." APDA - 104, April 8, 1955. American Turbine Corporation, (Private Communication) December, 1954. 43

84'- " DIAMETER 9o'-0" - 80 0 CYLINDRICAL. BUILDING ELEV. 106'-0|.. —-—' —-~=:: ~'. -- ~~~~~~~~~~~ROOF' ~~~~~~~~~~~~~~~~~~~~~~~~ELEV. -!l. ~~~~~~~~~~97'-0" CONDENSATE STORAGE TANKS A I FEEDWATER HEATERS - TURBINE GENERATOR [rr ~~~~~~~~~~~~~~~~~~~~~~~UI' FLEMNT |NAK EXPANSION TANK~ i I - V. 35 0 ELEMENT SODIUM'DISASSEMBLY PUMP 8 SHIPPING TOR STEAM..-, FAC ILITY,/GENERATOR _DO'HEATER FUEL' RADE TRANSFER CONDENSER PASSAGE FUEL~~~~~~~~~~~~~~~~~~~~~~~ELEV. O.Ol| J ELEMENT LAPUU(P DECAY NaKPUMP GAMMA8a NEUTRON SHIELDING j L..BOILER FEED PUMPS " — INTERMEDIATE HEAT EXCHANGER CONDENSATE PUMPS NEUTRON SHIELDING REACTOR ELEV.-41"-O"....,..~; FIGURE 15 ELEVATION OF PLANT (Courtesy of Atomic Power Development Associates, Inc.)

MAIN CIRCULATING M PUMP SHIELD RADIOACTIVE GAS STORAGE DRUM TURBINE.~ ~ GENERATOR REACTOR SALT PLUS FISSION REFLE PRODUCTS TO F. R STORAGE RLE FUEL PROCESSING COOLING CONDENSER WATER MODERATOR SALT DE-AE REATOR CIRCULATING LIQUID METAL METAL FUL FUEL SOLUTION FUEL PSHIELD MAKE UP METAL FUEL REACTOR FEEDMTER PUMP CM

TABLE 18 DATA ON REACTOR TYPE Liquid Metal Fuel GENERAL Name Brookhaven liquid metal fuel reactor (LMFR) Purpose Power and fissionable material production Neutron Energy Thermal Status Research and development (BNL) MATERIALS Fuel Enrichment U-233, alternate fuel U-235 Fuel Elements U-233 in bismuth Moderator Be or graphite Primary Coolant.Bi-U fuel, externally cooled by Na in heat exchanger FUEL Maximum Temperature in Fuel Element 950 Average Cycle Time Continuous fuel processing LIMITATIONS Requires highly enriched fuel, preheating for startup, formation of radioactive polonium, low solubility of uranium in bismuth, unproven design. ADVANTAGES High temperature at low pressures, continuous fuel processing and high burnup possible, possibility of breeding, no fuel element fabrication, small heat exchange surfaces. 46

pI I RD D SHIELD CONTROL RODS INTERCOOLER CORE I L. P.P COMPRESSOR COMPRESSOR, GAS.1~P~~~~~ ~~~TURBINE SHAFT TO PROPELLER PRECOOLER RECUPERATOR WATER FIG. 17 SCHEMATIC OF CLOSED CYCLE GAS COOLED REACTOR

This system offers distinct promise for high-temperature reactor operation when construction materials appear to be the limiting condition. Studies have indicated in closed-cycle, high-temperature pressure operation that overall efficiency in excess of 40% can be achieved. Application of the gas cooled reactor appears to offer good promise in mobile units for land, sea, and air. Data on this reactor type are presented in Table 19. Organic Liquid Moderated and Cooled Reactor Another possible reactor system would be to employ radiation resistant organic materials for coolants and moderators. One such development study consists in evaluating terphenyl as the organic fluid. Technical data are given in Table 20. 6.2.7.5 Long-Range Concepts Ideal reactors lie in conceiving systems which permit operation at high temperature, high specific power, and compactness. The resolution of such high temperature is dependent upon development of structural materials for containers. Among the more practical approaches in these directions are the efforts of North American Aviation. An example of basic principles in this direction is the heterogeneous liquid metal reactor (SGR). Table 21 gives some data on NAA proposed installation in the San Jose valley. A system being studied by the University from a pure research viewpoint is a fluidized bed reactor. This system is indicated in Figure 18. U02 powder or U02 impregnated in graphite powder is fluidized by a gas in a right cylinder. As fission takes place, fission product gases are removed continuously by the gas. The temperature is permitted to rise to about 25000~F. Heat transfer is by radiation controls. Heat transfer surfaceslocated in the reactor provide means for absorbing radiant energy. Calculated transfer rates of 80,000 to 100,000 BTU's per hour per square feet appear in order, depending upon the fluid employed for absorbing the energy of fission. Present efforts have not reached the stage where it is possible to predict any practicality for this study. 48

TABLE 19 DATA ON REACTOR TYPE Gas Cooled GENERAL Purpose Test stand operation Neutron Energy Thermal Status Detail design MATERIALS Fuel Enrichment U02 Fuel Elements Plates, sandwich Fuel Element Jacket Stainless steel Moderator H20 Primary Coolant Air FUEL Maximum Temperature in Fuel Element 1800 LIMITATIONS Low heat transfer coefficients, induced radioactivity in coolair required, operation of "hot" turbines, high pumping costs for circulating air. Successful operation not proven. Unproven design. ADVANTAGES High operating temperatures, relatively low pressures, light weight. 49

TABLE 20 DATA ON REACTOR TYPE Organic Liquid Moderated and Cooled GENERAL Name Shipboard nuclear power plant Purpose Shipboard power Neutron Energy Thermal Status Preliminary design MATERIALS Fuel Enri chment U Fuel Elements Rectangular plates Fuel Element Jacket Aluminum Moderator Terphenyl Reflector Terphenyl Primary Coolant Terphenyl FUEL Sheath Temperature OF 800 Average Cycle Time 90 days LIMITATIONS Heat transfer coefficient low, polymer formed in coolant, requires terphenyl purification system. Possible high terphenyl losses, unproven design. ADVANTAGES Negligible corrosion, low pressure at high temperature. 5o

TA.BLE 21 DATA ON REACTOR TYPE Liquid Metal Cooled GENERAL Name SGR sodium-graphite reactor Purpose Power generation Neutron Energy Thermal Status Construction MATERIALS Fuel Enrichment U, slightly enriched in U-235 Fuel Elements Rods in clusters Fuel Element Jacket Stainless steel Moderator Graphite Reflector Graphite Primary Coolant Na FUEL Maximum Temperature in Fuel Element 1200 LIMITATIONS Use of Na in primary loop, four coolant loops used, Na, Hg, organic liquid and water. Hg vapor toxic. Large size with such low enrichments. ADVANTAGES Relatively low cost of graphite, high temperature stability of graphite with negligible vapor pressure. 51

STEAM 1 FIG. 18 / WATER PREHWATER FLUIDIZED BED REACTOR SYSTEM I I ENGINEERING RESEARCH INSTIUTE I SATURATED I UNIVERSITY OF MICHIGAN STEAM DRUM II ~~~~~~FEED DESIGNED BY H.A.O. WATER DRAWN BY R 1. K. 11 I CHECKED BY M.E.W. FEED ATER I | TFEED WATER I TUBES ALL METALLIZED FINES TO REACTOR SEFRATOR WALL FROM PELLET I MACHINE I /VISBRATOR i'~~~! ~TO CHEMICAL FEED PROCESSING HOPPER CHROMEL ALUMEL _...;'1 _ _ ___ ___ _ __THERMOCOUPLE FLUIDIZED BED REACTOR SOLIDS SOLIDSFEEDER I I FLOW RECORDER _______ CONTROLLER NEUTRON'REFLECTOR CONSTANT HEAD BOUNDARY OF GAMMA SHIELD

7.0 FUEL SEPARATION 7.1 Introduction As operation of the reactor continues with a given fuel charge, the concentration of fission product material increases, and consequently neutron losses due to absorption by the fission products increases. Ultimately, a condition is reached in which the original fuel has produced enough fission products so that the nuclear chain reaction can be no longer sustained and the initial charge of fuel must be removed and replaced by purified fuel. Another type of behavior exhibited by metallic nuclear fuels undergoing irradiation is that of radiation damage. As a consequence of operation at elevated temperatures, and as a consequence of the production of the fission products within the crystal lattices of the nuclear fuels, the fuels themselves undergo structural changes which are deleterious to their mechanical and thermal functioning. Consequently, both radiation damage and fission product buildup constitute reasons why nuclear fuel must eventually be removed from a reactor and replaced by purified and reconstituted fuel. Fuels which are no longer suitable for reactor operation might be discarded in some suitable manner except for two reasons. The first of these reasons is that only a fraction of the fissionable material originally charged to the reactor will be consumed before radiation damage and fission product buildup necessitate removal from the reactor. Consequently, if the fuel were discarded, much valuable fissionable material would also be discarded along with the waste products. The second reason why the fuel cannot be discarded is that in reactors which contain any uranium-238, the capture of neutrons by the uranium-238 results in the production of plutonium which is a reactor fuel too valuable to discard. Consequently, it is found that irradiated reactor fuels must be treated in some manner so that the fissionable uranium and plutonium may be recovered from these fuels for re-use as reactor fuels. 7.2 A queous Methods In the following discussion, various means will be described-of accomplishing the treatment of irradiated nuclear fuels in such a manner that fissionable materials are recovered for re-use. The first method of fuel separation which will be described is aqueous chemical processing. Aqueous chemical processes are applied to the separation of uranium, plutonium, and fission products, when the component parts of the fuel must be separated in high degrees of purity. For heterogeneous reactor fuels in which the fuels are discreet bars of metal surrounded by a moderator and coolant, it is necessary to dissolve the solid fuel elements in acid. The dissolution is conducted in such a manner that the resultant solution has properties which will permit effective chemical separations. Since ordinary or light water is used in aqueous chemical separations, an ideal application of the aqueous method is the separation of fuels in a

light water homogeneous reactor. If heavy water is used in a homogeneous reactor, it is necessary to remove the heavy water from the dissolved salts of fissionable material, since the heavy water is so expensive, and to redissolve the dehydrated fuel and fission product salts in light water for subsequent chemical processing. The separations of uranium, plutonium and fission products may be accomplished by one of three aqueous methods or combinations thereof. These methods are: 7.2.1 Precipitation. 7.2.2 Solvent extraction. 7.2.3 Ion exchange. Earlier methods of aqueous chemical processing employed a precipitation technique. The use of bismuth phosphate permitted the selective separation of plutonium from a mixture of uranium and fission products. This permitted plutonium isolation in pure form, but did not permit the separation of uranium from highly radioactive fission products. As an example, consider a case of recovering fuel from a reactor. A reactor operating at a power level of 100,000,000 watts (100 megawatt days) will fission about 100 grams of fuel per day. This means that 100 grams of fission products are going to accumulate in the reactor core every operating day. These fission products act as poisons, and will eventually stop the self-sustaining fission reaction and shut the reactor down. When this occurs, the reactor will still contain appreciable quantities of fissionable material, which at $20.00 per gram represents too high an investment to discard. Methods of separating the fission products from the fuel, so that the fuel can be returned to the reactor, are then necessary if reactors are to produce power on an economical basis. Some processes for separating fission products from nuclear fuels are classified, so any discussion at this time must be limited and very unspecific. However, the magnitude of the problems and the fields in which problems exist can be pointed out. Separation of fission products from spent fuel is a very difficult problem for several reasons: 1) fission products are extremely radioactive, which makes it necessary to conduct all operations behind thick concrete shields, using techniques that were entirely new to the chemical industry, 2) the basic problem of separating uranium from some 30-odd other elements is not easy to begin with, 3) for most reactor fuel uses, the purity specifications set for the product are such that about one part fission.product per million parts uranium is all that is permissible. At the present time separations are made using solvent-extraction-techniques. These processes are capable of fulfilling the above requirements technically and at the same time furnish a means of separating artifically-produced materials, such as plutonium-239 from uranium-238 and uranium-233 from thorium-232. However, initial and operating expenses for such processes 54

are high, and will require considerable reduction before fuels from power reactors can be economically processed by such means. As an example of a solvent-extraction processing plant for the separation of uranium, plutonium, and fission products is shown Figure 19. In this process, it is assumed that a metallic fuel element is used in which the uranium, a mixture of uranium-235 and uranium-238, is perhaps alloyed with aluminum, and the alloy itself jacketed with an aluminum layer. This fuel element has been in the reactor sufficient time, so that the optimum burnup and plutonium buildup have occurred. It is also assumed that the fuel element has been stored long enough for all the neptunium formed in the element to decay to plutonium. This element is dropped through the slug chute.into the dissolver, where the metal is dissolved in nitric acid. The dissolver solution is jetted to a feed makeup tank, where the nitric acid and uranium concentrations are adjusted to suitable extraction concentrations. This feed is then pumped to the extraction, or "A" column. The columns shown in this flowsheet are typical pulse columns. The column contents are pulsed by the reciprocating piston shown at the base of the column. This pulsing action pushes and pulls the liquid contents through a series of pierced plates that are spaced approximately two inches apart in the small section of the columns. The pulsing action disperses the heavy and light phases very thoroughly into one another, and results in very good contact. Enlarged sections are provided at the ends of each column to allow the heavy and light phases to disengage from one to another. In "A" column, an organic phase, tri-butyl phosphate, dissolved in kerosene, is introduced into the base of the column. This organic phase is lighter than and immiscible in water and water solution, so it rises up through the column. In its passage through the -lower section of the column, the organic phase extracts uranium and plutonium from the aqueous solution coming down from the feed point. Fission products are not extractable by this phase, and thus remain in the aqueous solution and pass out the bottom of the column into large storage tanks. After passing the column midpoint, the organic phase in its passage through the upper section of the column is scrubbed free of the last traces of fission products by the scrub solution introduced at the top of the column. It is then collected in the upper disengaging section, and overflows into "B" column. "B"t column's function is to separate the plutonium from uranium. This is done by adding a reductant solution to the top of the column. This reductant changes the valence state of plutonium, so that plutonium is no longer extractable by the organic phase. Uranium is unchanged by this treatment, and so remains in the organic phase. Plutonium, free of uranium, then comes out in a water solution from the base of "B" column, while uranium, free of plutonium, remains in the organic phase which cascades over into "C" column. The function of "C" column is to strip uranium from the organic phase into an aqueous solution. Stripping is done by using water or very dilute acid solution in place of the concentrated nitric acid solution used for extract tions in "A" column. The uranium in a very pure form leaves the bottom of 55

FIG. 19 TYPICAL PROCESSING FLOWSHEET FOR SEPARATING PLUTONIUM, URANIUM, AND FISSION PRODUCTS BY SOLVENT EXTRACTION NITRIC ACID NITRIC DEMIN. PLUTONIUM DEMIN. DEMIN. DEMIN. SODIUM ACID WATER REDUCT ATER WATER WATER CAR ONATE DEMIN. WATER URANIUM URANIUM SOLVENT SOLVENT SRBSCRUB STRIP WASH WASH SOLUTION B SOLUTION WATER SOLUTIN PLUTONIUM METAL FUEL ELEMENTS ~~~~~~~~~~~~~~I e < e > e~~~FF REMOTELY VENT OPERATED VALVE TO OFF GAS SYSTEM VENT VENT NITRIC HNO3 ACID DEMINERALIZED WATER II1"A i VENT COLUMN HP S\~R STEAM STEAM OR JT FEEDC COOLING WATER DISSOLVER MAKE-UP COLUMN STEAM SOLVENTSOLVENT TSOLVENT t SOLVENT __~ - REMOTE HEAD DIAPHR/~..-.-.-.-.-.-.-.-RMPUMP B" CKLUMN -SYMBOLS DIAPHRACOTOM COLDMT VALVE RA lgAC O TUI SOLVENT -COLUMN PULSER OR DRIVE PISTON' TO COLD AREA FOR REMOTE HEAD PUMP HP STEAM SOLVENT SOLVENT.'IEJ — -FLOW SENSING DEVICE (ORIFICE OR REMOTE INDICATING ROTAMETER) F-~~ o* *',TO, -FLOW CONTROL MOTOR VALV RADIOACTIVE MAY BE REMOTELY OPERATED WASTE DISPOSAL RADIOAISOLVENT ACTIVE B PLUTONIUM URANIUM WASH sTEO SOLUTION SOLUTION AQUEOUS WASTE TO TO TO PLUTONIUM URANIUM WASTE PROCESSING PROCESSING DISPOSAL

"C" column in a water solution. The organic phase cascades from the top of "C" column to the bottom of "D" column. "D" column is designed to scrub the organic phase free of any residual traces of uranium of fission products, and at the same time remove any deccmposition products from the organic phase, that may have formed in the process. Scrubbed and essentially pure solvent from "D" is then re — circulated by means. of pumps back to "A" and "B" columns. The uranium and plutonium solutions from this process are free of radioactive fission products and can be handled without danger. These elements in solution are routed to metal-reduction processes and may be ultimately used again in the reactori One factor that contributes to chemical processing costs is the disposal of the radioactive fission products. At the present time, these wastes are stored in large tanks, which means more tanks must be built as the ones in use fill up. Obviously, this is a stopgap measure that will be abandoned when more suitable disposal methods are worked out. Another major problem of operating nuclear power reactors in populated areas is the gases that are liberated during reactor operation and during chemical processing of the reactor fuels. These gases are formed during fission, as fission products, or are present as a result of decay of a fission product through a gaseous phase. They are intensely radioactive, and as such cannot be released indiscriminately into the atmosphere. At present, these gases are handled by shooting them up a tall smokestack and depending upon the dilution by the atmosphere to reduce the concentration of radioactivity to a tolerable level. Obviously, the safety of this method is dependent upon atmospheric conditions, such as wind velocity, wind direction, temperature conditions, and to a large extent the existence of a large uninhabited area to give the radioactive gases time to be diluted. Where a nuclear power reactor is to serve a highly populated area, other methods of handling these gases would have to be used. Processes have been worked out for removing radioactive gases from inert gas streams, but cost data on such processes are not firm at this time. Methods of aqueous chemical separation employing ion exchange techniques offer promise in certain uranium separations, plutonium purification, and in the isolation of specific radiochemicals from the solution of fission products. 7.3 Fluoride Volatility Methods An alternative to the aqueous chemical processing technique for the separation of uranium, plutonium, and radiochemicals, is that of the fluoride volatility technique. The basis of the fluoride volatility technique is that uranium hexafluoride is a volatile material which condenses at conditions not far removed from ordinary temperatures and pressures. There would seem to be the possibility, therefore, of forming uranium hexafluoride from the uranium present in irradiated nuclear fuels and then distilling this uranium away from the plutonium and fission products in the form of 57

the uranium hexafluoride. The residual material from the distillation may be treated further as required, and the uranium for recycle to a reactor, or the uranium hexafluoride may be charged directly to a gaseous diffusion plant for re-enrichment of the uranium-235 content. A block flow diagram of a representative fluoride volatility process is shown in Figure 20. 7.4 Pyrometallurgical Processing A third method for the treatment of irradiated nuclear fuels to render these fuels suitable for re-use in a nuclear reactor is that of pyrometallurgical treatment. Pyrometallurgical methods have the common feature of preserving the chemical state of the reactor fuel during processing. Consequently, a minimum of chemical conversions are required in this method of fuel treatment. Alternative pyrometallurgical processes are: 7.4.1 Melting and re-solidification of the fuel. 7.4.2 Extraction of the molten fuel by means of metals or fused salts. 7.4.3 The distillation and condensation of fuel metals at high temperatures. 7.4.4 Zone melting. Pyrometallurgical processes are quite straightforward in concept. These processes are dependent, however, upon materials, capable of withstanding high temperatures. With present knowledge of high-temperature materials, melting and extraction have attractive features. Melting alone has application to fast reactors where rigid specifications of purity in the fuels are not essential. Extraction at high temperatures is a technique whereby separations between uranium, plutonium in the fission products, as well as structural materials may be achieved. (See Figure 21). 7.5 Use and Storage of the Fission Products Economical nuclear power may be contingent on the successful development of large-scale industrial uses for the extensive quantities of fission products produced in nuclear chain reactors. Thus far, the fission products have constituted a high-cost liability. Their presence in reactor fuel elements requires expensive chemical separations plants to provide purified nuclear fuel suitable for re-use in reactors. Present as wastes after chemical separation, the fission products incur an even greater expense in handling and storage. Economic studies indicate that handling and storage costs may approach 60 percent of the total costs of chemical separations. The consumers of reactor power will bear the expense of these operations, unless methods are devised to defray the cost by industrial utilization of the fission products. Research groups from industry and the universities are presently striving to resolve the fission-product problem by investigating potential uses for the fission products. Many of their findings have previously been put to profitable use, and some show definite promise for future applications; others are highly speculative. The final solution to 58

BROMIN E TRIFLUORIDE IRRADIATED FUEL MAKE UP' REACTION |VOLATIE FIS BROMINE T FLUORIDS — _< DISTILLATION TRIFLUORIDE I URANIUM HEXAFLUORIDE PLUTONIUM AND FISSION PRODUCT FLUORIDES AQU EOU S CHEMICAL PROCESSING PLUTO NIUM FISSION PRODUCTS F/ G. 20 BLOCK FLOW DIAGRAM OF A FLUORIDE VOLATILITY PROCESS 59

IRRADIATED FUEL MOLTEN SLAGGING OR MOLTEN URANIUM EXTRACTION FLUX SLAG CONTAINING PLUTONIUM AND FISSION PRODUCTS DISTILLATION AUXILIARY OR EXTRACTION FLUX PLUTONIUM FISSION PRODUCTS FI G. 21 BLOCK FLOW DIAGRAM OF A PYROMETALLURGICAL PROCESS 6o

this challenging problem will determine the degree to which power from nuclear reactors will compete in a free market. 7.6 Storage of Fission Products These materials must be maintained in biologically safe locations. If the fission products are to be regarded as wastes, one may consider dispersing them in the atmosphere or in the ocean, casting them in concrete or clay and burying them in special plots or at sea, storing them in tanks as aqueous solutions, or in the form of solids, etc. Dispersal appears to be unsafe for the very huge quantities produced by a nuclear power industry. Consequently, there is strong incentive to develop economical methods of containment.' The most economical storage method would probably be that in which fission products are contained in the smallest volumes in order to minimize the costs of surrounding shielding. In the case of the long-lived fission product nuclides such as strontium-90 and cesium-137, continued addition of a stockpile at a constant rate will eventually yield an equilibrium value of the radioactivity (in curies) of the nuclide in question. This equilibirum value may be calculated through: (curies at equilibrium) = 8.45 x 10-3 (power level in watts)(fission yield, %) where the power level refers to the sum of the gross power levels of the reactors adding the fission product to the stockpile and the fission yield is given by a fission product distribution curve. Thus, a reactor operating at 100 megawatts eventually builds up a stockpile of 4.5 megacuries of strontium-90. The time required to accumulate this much strontium-90 will be two or three times the half-life of strontium-90 or 40 to 60 years. 7.7 Use of Fission Products Much heat is evolved as fission products decay and so megacurie amounts of fission products are useful as heat sources. A great variety of other uses for fission products are being investigated. A listing of these is of temporary validity, since new uses are rapidly being discovered. 61

8.0 BY-PRODUCTS OF NUCLEAR ENERGY 8.1 Industrial Utilization of Fission Products 8.1.1 Introduction Economical nuclear power may be contingent on the successful development of large-scale industrial uses for the extensive quantities of fission products produced in nuclear chain reactors. Thus far, the fission products have constituted a high-cost liability. Their presence in reactor fuel elements requires expensive chemical separations plants to provide purified nuclear fuel suitable for re-use in reactors. Present as wastes after chemical separation, the fission products incur an even greater expense in handling and storage. Economic studies indicate that handling and storage costs may approach 60 per cent of the total costs of chemical separations. The consumers of reactor power will bear the expense of these operations, unless methods are devised to defray the cost of industrial utilization of the fission products. Research groups from industry and the universities are presently striving to resolve the fission-product problem by investigating potential uses for the fission products. Many of their findings have previously been put to profitable use, and some show definite promise for future applications; others are highly speculative. The final solution to this challenging problem will determine the degree to which power from nuclear reactors will compete in a free market. The radioactivity of the fission products is due to the unstable form in which they are produced. It is characterized by the spontaneous emission by the fission products of nuclear particles or rays, in their attempt to attain a more stable state. The particles emitted are negatively charged electrons, called beta particles, with short ranges and capable of only superficial penetration of matter. The rays given off are electromagnetic rays similar in nature to x-rays. These "gamma" rays exert their effects over a much longer range and are extremely penetrating. The primary effect of both types of radiation is the ionization of the material through which they pass. This ionizing effect makes possible the detection of radioactivity, permits sterilization of food and drugs, promotes chemical reactions, and is responsible for many other effects discussed in subsequent sections. The use of radiation in these and similar processes is not new to industry. Many manufacturers are presently making machines capable of producing ionizing radiations similar to those emitted by the fission products. However, the fission products have the advantages of greater versatility in source design, absence of mechanical or electrical breakdowns, and may be supplied at less cost for a given amoiAnt of radiation, once a market is established. 62

8ol.2 Classification of the Fission Products After a fuel element is removed from a nuclear reactor, it goes through a series of chemical processes to separate the fuel from the fission products produced during operation of the reactor. The resultant mixture of fission products and chemical wastes present in water solution or as slurries form the usual plant -waste stream. Gross fission products exist presently in storage at various sites in a variety of different chemical states and in a wide range of concentrations. A potential use of fission products may require a specific type and energy of radiation different from that of gross fission products. Important to such users would be the specific activity (amount of radioactivity per pound) and the half-life of the material. Maximum utility of the fission products lies in the ability to manufacture them in such a manner that they possess specifications applicable to a wide range of users. Certain uses may demand a product which consists of a relatively large proportion of an inert material, through which the fission products are dispersed. Other uses may demand high specific activities of fission products, or fractions thereof, in which, essentially, the total mass may be the fission products in a particular chemical form. For these reasons, there are general classifications of the fission products by their state of chemical separation and refinement. Waste streams containing fission products must be handled in a variety of ways, depending upon the requirements of the fissionproduct user. To increase the specific activity of the gross fission products, some of the inert components must be removed. In this stage of chemical treatment, the fission products are classed as semi-refined. If a need exists for a particular type of radiation, additional separations could be performed to reduce the semi-refined fission products to a number of specific radioisotopeso After the required chemical processing, the fission products are redefined as mixed fission products. Such a degree of processing may be economical, if beta-emitters were all that are required for a particular application. The absence of the highly penetrating gamma rays would lessen the shielding requirements, resulting in lower structural cost, which could offset somewhat the costs of chemical treatment. Individual or separated fission products, with applications as tracers or long-lived, high-level radiation sources, are produced with additional chemical processing. Higher prices for the fission products reduced to individual radioisotopes would be offset by their ability to more adequately meet the needs of potential users. 8.1.3 Development Investigations are being conducted, whereby the gross fission products can be converted to products possessing specifications which have marketable use. Some of these investigations are discussed on the following page.

8.1.3.1 Adsorption It appears that uses can be developed for fission products dispersed through selective inert adsorptive materials. In general, the products produced from such treatment may have lower specific activities than materials produced by other means. As an example, it appears possible to develope usable products by adsorbing fission products contained in an aqueous chemical solution in activated clay. It may be possible to cast such a clay, containing known quantities of fission products, into geometrical forms that permit ready handling, shipment, and use of the resultant product. Dependent upon developed end use, investigations may reveal a number of selective adsorbents which might be used, depending on the properties required of the end product. 8.1.3.2 Concentration by Evaporation By employment of novel designs, it appears feasible to effect concentration of the fission products as they exist in conjunction with present metallic salts possessing high melting points. These molten solutions or slurries could be cast into suitable shapes. Under certain conditions, it may be possible to achieve products which contain very high specific activities. Extensive use of this method will necessarily depend on the development of containers into which the material can be solidified, packaged, and shipped. 8.1.3.3 Concentration by Chemical Conversion Another feasible method would be to convert present fission product compounds to different states, which could permit safe storage over long periods of time. As an example, conversion of nitrates to oxides can accomplish a forty-fold reduction in volume. This field of investigation offers intriguing potentialitites in effecting considerable savings in processing costs, as well as production of fission products in useful form. 8.1.3.4 Selective Separations of Short Lived Fission Products from Long-Lived Groups It appears feasible to consider investigations of methods of separation of fission products possessing long half-lives, in concentrated form from the mass of chemical salts and those fission products which decay rapidly to inert materials. An employment of such investigations appears realistic when employing ion-exchange techniques. It may-be possible by such methods to reduce the volume of the long-lived fission products to about five per cent of the volume of the original solution. 64

8.1.4 Uses of the Fission Products Potential uses of fission products are many, provided the price of the products can be held down. Development of economical processes to separate fission products into usable forms are needed before full use of these products can be realized. The radioactive fission products are finding increasing applications in industry, both in research and process control. Another apparent and widely discussed area of investigation lies in the potential use of gross fission products as sources of energy, from which heat can be obtained. The development of such heat-energy sources is contingent upon processing of gross fission products which yield a product that has concentrated activity, and can be maintained for long periods of time at high temperatures. Since transportation of high-energy source products poses a major problem, one of the more obvious areas of utility lies in auxiliary preheat systems for nuclear power plants. Use of the fission products in this manner would also have the advantage of maximum utility of energy from short-lived fission products. Subsequent to the development of preheat systems for nuclear power plants, one use of fission products could be their application in similar duty in conventional power plant. Obviously, this would entail the solution of the additional Droblems of handling, storage, and transportation. Dependent upon the energy level and temperature conditions, it appears that generation of steam from packaged fission-product boilers can be developed. Development of such utilities for concentrating energy sources is a challenge to the imagination, and requires resolution of a great many technological problems. Successful resolution of these problems may lead to utilization of concentrated gross fission products in industrial applications in heating, ventilating, and air conditioning. With highly concentrated energy sources available, possibilities arise for reversibility, so that such energy could be utilized for refrigeration. Such a facility would be similar to the gas-burning refrigeration units available on the market. However, the generation unit for the refrigeration cycle requires remote location and heavy shielding, so this utility appears to be confined to large installation. Another very broad and diversified field of application for the gross fission products as sources of energy lies in areas of use in the manufacture of chemicals and petroleum products. The effects of radiation on chemical reactions are not new. However, the industrial application has not been feasible until this time, because of the lack of cheap sources of radiation. With the vast quantities of fission products available from nuclear chain reactors, some of the reactions have great industrial promise. A number of possible applications in radiation chemistry have been suggested in the Stanford Research Institute Report, Industrial Uses of Radioactive Fission Products, and are indicated in Figure 22. In 65

FIG. 22 POSSIBLE USES FOR FISSION PRODUCTS STERILIZATION INSECT & FUNGUS CONTROL IONIZATION OF GASES PHARMACEUTICALS, GRAINS STATIC STATIC PARTICLE FLAME GAS DISCHARGE LUMINESCENT FOODS INSTRUMENTS MEDICAL SUPPLIES AGRICULTURAL PROD. ELIMINATION PRECIPATATION PROPAGATION TUBE PIGMENTS CONTROL OF INSECTS CONTROL FUNGUS CLEANING OF IMPROVED INTERNAL IMPROVED FLUORESANTIBIOTICS CANNED FOODS TEXTILES INSTRUMENT DIALS IN STORED GRAINS GROWTH INSIDE STACK GASES COMBUSTION ENG. CENT LIGHT TUBES OF INSTRUMENTS ELIM. OF INSECTS IN PREVENTION OF ADHESIVE BANDAGES DRIED EGGS UMER PACKAES COFFEE PLANTS BLOWOUTS IN JETS ELECTRONIC TUBES ROAD SIGNS CONSUMER PACKAGES BLOWOUTS IN JETS PRE -PACKAGED IMPROVED HEAT IDENTIFICATION SUTURES FLOUR MILLING FRESH FRUITS BURNER PERFORMANCE MARKERS 0I FLUID CATALYST ON BABY PRODUCTS CHEESE SURFACES BEDS IN PETROLEUM REFINING RADIATION CHEMISTRY PENETRATION OF MATTER PHYSICAL EFFECT MOLECULAR POLYMERIZATION HALOGENATION OXIDATION REARRANGEMENTS RADIOGRAPHY RADIOLOGY INSTRUMENTS TRACERS FOAM REDUCTION HYDROCARBON PROD. VITAMIN "D" EXAMINATION OF FLUID FLOW PLASTICS MFG. CHLORINATION THERAPEUTIC USES THICKNESS GAUGE ACCELERATION SYNTHESIS METAL CASTINGS STUDIES CURING HEAT PHOTO CHEMICALS DEVELOPMENT OF DEGRADATION FOPD PACKAGE LIQUID LEVEL AIR POLLUTION SENSITIVE MATERIALS REACTIONS NEW PETRO-CHEM OF CELLULOSE INSPECTION GAUGES STUDIES CURING NEW PETRO-CHEM. SPEED ALTERATION OF ORDNANCE OIL WELL FLOW OF GASES MONOMER FILMS DERIVATIVES DRYING PROCESS GLASS INSPECTION CEMENTING POLYMERIZATION VEGETABLE OILS SOURCE: IndustriaI Uses Of Radioactive Fission Products Stanford Research Institute

general) it can be stated that any chemical combination or dissociation that requires promotion or acceleration is worthy of investigation under some influence of ganuna irradiation. One of the fields of interest which offers vast opportunities for improvements in processes and products is polymerization. Such improvements can be accelerated by employing gross fission products. Polymerization is the process used in the production of long chain molecules, examples of which are the plastics —polyethylene and polystyrene. Preliminary feasibility studies have indicated that gamma-radiation-promoted chemical polymerizations will not be able to compete economically with conventional methods of production. However, possibilities lie in the production of new polymers which cannot be produced by present means, and in improving the properties of presently polymerized materials. Halogenation reactions, conventionally catalyzed either with a metallic catayst or light, show definite promise for -utilizing the fission products. Thle University of Michigan has been investigating the chlorination of aromatic compounds and the polymerization of olefins, using a high-level source of gamma radiation. This source has been used in numerous instances of cooperative research with industry. In addition to experiments on chemical reactions, investigations have been conducted at -the University of Michigan on the pasteurization and sterilization of foods. Canned raw frozen foods, canned fresh foods, fresh meats, vegetables, and grains have been studied to determine the effects of gamma radiation on the storage, taste, and wholesome properties of foods. Another experiment, involving a long-term animal-feeding program, was designed to investigate the effects of an irradiated diet on the normal growth characteristics of a large number of albino rats. The results of these studies have led to the design of radiation facilities to pasteurize meat and prevent sprouting in potatoes and onions, and another for the chlorination of aromatic compounds. Examples of the types of facilities considered for pasteurization of meat and prevention of potato sprouting are shown in Figures 23 and 24, respectively. In both of these designs, the materials to be irradiated are brought by means of a conveyor mechanism past a radiation source. In passing through the chamber, the material absorbs a certain amount of radiation, depending on the size of the source and the absorption characteristics of the material. The number of passes in the chamber made by the material depends on the dose or quantity of radiation required to produce the desired effect. In the meat pasteurization facility, pre-packaged cut-up meats could be treated at meat packing plants and sent directly to retail outlets. Some advantages of this facility would be the elimination of local butchering and extension of the shelf life of the meat. These and many other advantages are expected to produce economies, which would ultimately result in lower prices for the consurer. The potato facility was designed to help eradicate the losses suffered by potato farmers and processors as a result of sprouting. Tests performed at the University of Michigan revealed that, with the proper 67

............................~~::-::::''::::'::':P~::':::~i::-:::::l i~iX:::i":li~i:~::'::::~::":::::::: ":':-..........................~~ii::i:::ii:.~-i~~-:i:i:::::i:: ~i:::i:iii~ii~iiiiiiii''iiiiiii:i ii~::::::::i~~~~~~~~~~~~~~~~~~~~~~~~~~~i~~~~~ri~~~~~~~i~~~~~ri~~~~~~~i:-i~~~~~~~~~~~ji:::i:::ii:~~~~~~...............................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iii:i:::iii:i:.............~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i;~i:-:::::iii::.................~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iii:i~ii-ii:iiii:i:8:i-:i~~~~~~~~~~~~~~~~i:.:i:::::::i-i~~~~~~~~~~~~~~~~~~~~~~~~~i ii~~~~~~~~i- ixii~~~~~~~~~~~~ii::iii~~~~~~~~~~~~~iii-iiii iii~~~~~~~~~~~~~~~~~~~iiii~~~~~~~~~:i~~~~~~~i~-~~~~~~~i~::~~:~:~;;~~~~~~~~~~~~~~~~~~~i':i~~~~~~~~~~~~:-'iii'iiiii~~~~~~~~~~~~~~~~~~~~~~i'iaiii'iiiii~~~~~~~~~~~~~~~~~~~~~.......................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~~~~~:::~~~~~:............................. iii ii i~i i:iii ii~ii -i ii................. ~~ ii::::i:ii:::iii:i: ii~:`~:::~:~:::~::~::...................~ ~~ ~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~::::i-::~;i;:~-~::::~ ~iii~~ii::ii~:ii:............. ~iiiii~j~'ii.....................~ ~ ~ ~ ~~~~~~~~~~~~~~~~~i~:::i::i:~ii-~:_i................::~ iiijiiiii'iijiiliii~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iiiiiii'i'iii~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii'li~~~~~~~~~~~~~~~~~~ ~............................................i:::iiiii::i:iiiii-i~i:i iiiiiiiiiiiiiiii:::ii'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iii~~~~~~~~~~~~~~~~~~~~iii'::iii-:ii ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~....................................~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~i~ii-jiii~i~i-i: i::i i:ii~i:iiiiiiii:ii ij-iii;i:'i'i::ii::i-i i:iii:i:i:ii:iiiiii'.........................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~::ii:ii:ii-iii~i-iiiiii..............................~ ~~ ~~ ~~ ~~ ~~ ~~ ~ ~~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~~ ~~~ ~ ~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i:':iiiii~::::~i:~::: iliil-ii~~i iii......................~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~~~ ~~~~~ ~~ ~~ ~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~::ii'i~iii:ii''::':............................................................................. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ i::i~:~::::ii~::iiiii~:::ii:::::i~:~~~:i i:i.................................... ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~ ~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii:i:i:~::iiii:::::::ii; ii~'i-i'ii'Bi'i'ii'i'i~i'-jiiiiii aiiiiii:ii:'iiliiiiiii:',i'':::..........ii..............................~i:ii:i~iii::::i~~:::: jiiiliili~ii'i~.lii liiii l...........~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~::::::~::::::;~::~::~~~,iii;::i::i:i::................... iiii~l~ li:ii-::::iii:i~~-:~::::: ~::: i:..........~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~ ~~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:iiiii~i~iiiiiilii::-i:i:~-i::~~:::::~:::::::::::::........... iiiaiiri''iii:i'iiiii~ii'i'i::iii i -: -:::: i i - ii i i i: ii i: i:ii:i:::::i'::...........i~:iii:::::i~ii:ii ii::iii~~::iii:iiiii~~:: ij~::iii:::::; ~i: ~:............~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~::..............~~ ~~~ ~~~ ~~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~ ~~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii::~:i:i:i:::.....................i..ii:: i~~~ii~~~~i~~iiilili ~ ~ ~ ~ ~ ~ ~ ~...................................................................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:.......... ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii.............i ii~~~i..ifit...............~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'::::::;::::':'::::::::'............~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~''''':''iiiii.iiliiii:...........~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iiil~iiiiiiii~ii~i'i.........................................~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~~~ii::.::.:::::,.::::::iiii~::::i~'..............~ ~ ~ ~ ~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~iiiii:iiji1;'i:::~i:i;:::: ii:::::i:i ii::: ~::iii:-::::: iiii~~~iiii~~iiiiii::ii-iiii..................::~:~::~:-~::::ii::i::i~~~~~~~~~~~~~~~~~~~~~il::,:i~~~~~~~ii~~~i:::j:~iri:::i::: ~::::::::-:i:::~~~~~~~~~~~~~~~~~~~...........................................................~~~~~~~~~~~~~i~ ~ir::: i; i i~:::i ii i~'iii ii~i~i:: i~ i: ii;i i~ii iiii i~i iii'ii;':i~~~~~~~~iiiiiii............................................::ii......................................i:;i~'iil~~~iiiil~~i~~l'iii~~~iiiliiii~~~iiiiilili:.l::~-:~::~:.:~:~:::~:::~:~~:::::: ~ ~ ~ ~ ~ ~ ~ ~ x. V....................................................:iii~i::*E:::::-P::j.............~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:i~iij~''::ii j::::;::::g-.:; ~XIX_.;:':!:"-'I*1Xs!!1~;:l;;-~- -1CIY.*i~...ll'..:!.^...-'.........................li~iii~ii:i:::i:::i~::::ii::::;::-i:i i~:::i: ~' i~ii~i~ii:-'"::ili'~iiiii..........:: -:il::i::i~~~~~~~~~i~~i~;i~~~~~ii::::::i-:i:::i::::i:: ~ ~ ~ ~ ~ ~ ~ ~ ~................................................................... ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ i~::::ii:~::i~:i:iiii~:Xiii::::::iii:ii:::i::::::::~:~: ~ ~..................................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ii-iii:iiji~ii~~ii:::~...........................................i~i::: ii~i:: i::i~~i: i:.i::::~i::::i::::::::::::i~~~~~~~~~~~~~~~i::i~~~i:i~~~ii:::::::::::i:::i~~~~~~~~i-::i:.i~~~~~i::::i:-: i: -::i:::i.::i:::::i::i~~~~~~~~~.................... i F~~'::'ilio'isii''iii~~~~~~~~~iii~~~ii'i.....................

...............::::......:......:.:.............':......''.....................:.......... K..:.::........;:::L.:..:......,......................................................::.:::,.:.::-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.-"t............:......:......::.....:..................:.. - -..... -..........: -.............::..,...... - ~........:,~:'.:~:::..:......O,,I........ i.....i..::......-iB.....i...............::!,,~x:........ i.....i..i~i:i{ ~iii...................ii!::.:.:............... 1:i.:;1..1;......... ii -..i X i iii!!i:::...;ii.......iii............iii i:. i......l t.:. ii..iiiii.,-,:......I.:..............................:::.:...%..::..........................::.....:::::..:.... ii..............i.ii.iii::...:...:::.:...... ii..i.........:..: i.:-...:..i:.............i.......:~i ~:.i.. i...........S:;!........... i.............;i.!? i..ii.~. ii~.................................:..:....::::............i...~:.::..:....:::.....:-::...:.....i.B..........:.:....................:......;;......i...~..... —,......:.::...........:.........B...::.:.............:...i;!..;;'...... - %.. ~iB;B ~ ~ ~ ~ ~.:...::. r.:...:.:.....:............,...:.........!.... i:......: i... i:::::.......:..i:.:...i...i..i..::.:.i....::; i!:, i!:i.:il.:.......-i.......:.:.:.%.i..:.....::.:....!.:~....' i......:-:..:i!..B..............!.............. i..... iiii..% i............-........................ iii:::::.:.:.: _:..:.:.:.......:::::::...........;......;i.... X.............:.::~.:::........i.........:.iB:::.:.....:.:::::.:...:.... i;-.................. i~*iiii...::.:..:...:..::.......:..ii...i............................... * * *.:::..:..........-.........-........,i:.:. ii........!.~B................ -i:i$1:!ri:::..-.......... i.iii.iiii...:::..:-.-.:.:.:........:......:::...............:.................... i... "'. ~:::. -—....:::..ii:.....::..:..::.................:.....i!:..::::1....:.....:.:...........................1.:~::~...~!a.::%::.::........-.::i::.:::...:.:.:....i B i..::.......::.......i!!..................:x...... ii:::::..::.:.:....:.i..ii........i...%...... i.:::..:. iii.i.......-::...........i...1 yi m........iii..iiii:: -.::::.:....:..:.:::::.ii:........:..i.. i.::::::ii!.:i:.:.:..:%...::...::..:...i:.: B.....:::.~:...:::,.............:,......::..:..::....: %....:..::.-.:.:::..:.:.:: ~......:::........ -....:...... ii::.::::~-:........:iii:..:.:.:...::.:::....::..!i.............:.......::........i!!..:............ -.:..i.....%..%......m........... ~......:~1..................!....:........i. B..........:: ~....... ii......ii....8....................!!!....!.....: -...:.: -...........................: r:.:::,!..........:. -:,......:.......~;i......:..:......:.......::,{...E.:..::....:.....:........... ii- - 1 1 I I..........:..:.:..-::::...... ~il i!8!B!!:iaii. —..:.::..:....::....::....::.:.. -...:...........i:::.:..:.... —..i......:.-...... i.....:::......i -..... i..............................i.. I................:............-::. i......!...::.:.i!B.:.::.~:.: e......!........ i!..B.:.:..........!....... ili i::i:~........::.....: ~..........:ii??.~.....:-.............:~....::..-. 8!!i i; **...'.................:;;B!!i..:::..............................................:: -.....i.. B.~......:% -...i.:.............-......:..i...i;:....................:. ~!{~;..(............i. -.-.............. i..................9

dose of radiation, potato sprouting could be prevented for months, or indefinitely with a sufficiently high radiation dose. Potato processors who have to buy large quantities of potatoes at harvest time and then store them for long periods before processing would benefit considerably from such a facility. The uses of the fission products mentioned thus far depend on the fission products as a source of energy and for their ability to kill micro-organisms. Possibilities of other large-scale fissionproduct utilization lie in their use as radioactive tracers. The technique of using radioactive isotopes has been used to solve problems in all the physical sciences. Industry is finding numerous applications for small amounts of radioactive isotopes to be used as tracers. However, the phenomenon of radioactivity is not new to industrial research. As early as 1920, use was made of these techniques to investigate the solid state of lead. The widespread use of radio-isotopes at the present time results from the numerous types and large quantities available from nuclear reactors. The basic idea of the tracer technique is to mix some "tagged" (radioactive) isotopes among the stable isotopes of a test mate.rial. Since radioactive atoms can be detected by their radiations, they indicate the position and amount of test substance in the body of the material. Radioactive isotopes may be "manufactured" by two methods. One is to expose a material to neutron bombardment in a nuclear reactor to make it radioactive for use as tracer material. Fission products themselves, being highly radioactive, are the other source. This study is concerned only with fission products, as they are an unavoidable by-product of nuclear power. Some of the uses to which tracer isotopes can be put are studies in flow components of process operations, metering of fluids, and as leak detectors in pipe lines. The determination of friction, wear, and corrosion rates in inaccessible places may prove easy, using this means. Certain elements of the fission products, such as strontium-90, are used in commercial thickness gauges in the paper and plastics industry. Large savings are effected by narrowing tolerance limits and achieving better process control. Radioisotopes have been successful in eliminating static accumulation in flour mills, cement industries, and paper and textile plants. Mostly, naturally-occurring radioisotopes have been used up to the present. These may be supplanted in this use by fission products which have a greater range of the beta radiation. If successful, the fission-product radiation will help reduce the fire and explosion hazards present in these types of plants. These are but a few of the many uses for fission products. Figure 22 shows many more possible applications. This list will continue to expand as sources become more readily available, and more people are trained. 70

8.2 Influence of Nuclear Energy on Technology -The advent of the nuclear energy era has altered the technology of all phases of scientific endeavor by providing researchers with new tools of investigation. Many of the complexities of chemical, metallurgical, and engineering processes, heretofore unassailable by conventional methods, have been resolved by using man's newly gained knowledge of nuclear energy. There have also been many advances made in the study of the fundamental processes of life by medical and biological researchers employing new techniques developed as a result of the atomic energy program. 8.2.1 Chemistry Utilization of nuclear energy has brought with it some severe problems in the fields of analytical, physical, and organic chem.istry. The major problems have been how to analyze or measure physical properties of substances that are highly radioactive. In many cases, analysis must be made on very small quantities of substance, and frequently the analysis must be completed in a very short time, as the substance may be changing to a different element by radioactive decay. These problems have been met by several approaches, and where new approaches are worked out, new applications are rapidly found. For example, a process for the separation of plutonium from uranium and fission products was based on chemical properties worked out by Dr. G. T. Seaborg and co-workers at the University of California, using quantities of plutonium smaller than the head of a pin. The chemistry of neptunium, an isotope of which is the predecessor of plutonium-239, has been worked out. Tlis element is highly radioactive and decays rapidly, resulting in radiation hazards; so the work was performed using very small quantities. New elements americium, curium, berkeliumrn, and californium have been discovered and their chemical properties worked out, using similar techniques. Separation of elements in the rare-earth series has been achieved, largely due to the efforts of Dr. F. H. Spedding and co-workers at Iowa State College. These separations have been made by using ionexchage techniques. Heretofore, these elements could be obtained only in the impure state. Work on chemical separations of elements with closely related chemical properties by chelation-solvent extration methods has been investigated extensively at all of the national laboratories. These methods are now used in preparing zirconium, and the separation of of zirconium from hafnium, which is a difficult task by conventional chemical methods. These methods are also used extensively in purifying uranium and thorium for reactor purposes. Similar procedures could be used for other separations, such as nickel from cobalt or iron from manganese. 71

A major contribution to analytical chemistry has been the development of tracer techniques as analytical methods. As an illustration, assume it to be necessary to determine the part of impurities in a chemical process. Tracer isotopes of the ili;purity are added to the raw material, and after the ratio of impurity to tracer is established by a conventional analysis, all subsequent impurity concentrations can be determined by placing a sample into an instrument that counts the radioactivity. From the counter results, the impurity is easily determined. The chief advantages of this method of analysis are in the speed and accuracy with which determinations can be made. Major cost savings in analytical chemistry budgets have been achieved by these methods. If the beta or gamma emission from several tracers have different energies, counter instruments are available that will determine the activity on only one emission energy at a time, so several tracers can be carried through analytical procedures simultaneously. Considerable study has been given to the subject of physical properties as process control indices. Properties, such as infra-red, adsorption, gamma emission, as well as the more ordinary physical properties, are being extensively investigated as process control and automatic analyzers. Instruments utilizing many of these new developments should be available in the next few years. All of these developments are presently or will become very useful tools to industry. 8.2.2 Metallurgy One of the major technical problems confronting the designers of nuclear reactors is the proper choice of the materials used in reactor construction or as coolants and moderators. The materials used in reactors must conform to operating conditions, which can vary over wide limits of temperature and pressure. The extreme quantities of heat produced in nuclear reactors must be dissipated, and as such, it functions as a type of heat exchanger. The materials chosen for reactor duty would have to meet requirements similar to those imposed on a heat exchanger operating under the same conditions. Not only must materials meet these general requirements, but they must also have the proper nuclear properties. Of primary concern to continuing reactor operation is the need for maintaining the supply of neutrons throughout the reactor. The nuclear properties of many materials are such that, by parasitic absorption of neutrons, the supply is decreased and the fission reaction inhibited. Also, the neutrons resulting from fission may alter the physical properties of a material so that it is no longer usable. Such phenomena are generally referred to as radiation damage. Many construction materials normally used have poor nuclear properties. Research engineers, metallurgists, and physicists have been working hand in hand to develop new materials which have the necessary physical, mechanical, and nuclear properties suitable for use in nuclear reactors. 72

The MTR (Material Testing Reactor) was designed and built for the express purpose of determining the behavior of materials exposed to high neutron irradiation. Efficient removal of the heat generated in nuclear reactors at high temperatures has promoted the use of liquid metals as coolants. Water, heavy water, and air have been used, but do not have comparable heat transfer properties. Another advantage of liquid metals is that they can be used at atmospheric pressure, while water cooling would require pressurized systems to maintain the high working temperatures required. In addition to pure metals, the use of alloys has been mentioned. Prominent among these is the NaK (sodium-potassium) alloy, which melts at room temperature and has fairly good nuclear properties in the intermediate and fast neutron ranges. Use of liquid metals results in corrosion problems for most materials of construction. An additional problem is pumpiig these metals at the high temperatures involved. The corrosion and pumping problems that arise from use of molten metals are still not completely solved. In the realm of construction materials, the metal zirconium has received considerable attention, since it has the lowest absorption cross section for thermal neutrons, of all mechanically strong, corrosion-resistant materials. Zirconium is a preferred material of construction for power-producing reactors operating at temperatures below 800~F. The importance of zirconium resulted from the development of production processes which were economically feasible. Separation processes were developed at Oak Ridge National Laboratory to remove the contaminating element hafnium, which is always associated with zirconium. Hafnium has high neutron-absorbing characteristics, so its presence in the zirconium is very undesirable. The two principal methods of producing zirconium and hafnium on a commercial scale are the hot-wire process and the Kroll process. The hot-wire process consists of the thermal decomposition of gaseous zirconium and hafnium iodides on a heated tungsten wire. The more expensive hot-wire process has been replaced by the Kroll process, which consists of the reduction of gaseous zirconium chloride with fused magnesium in-an inert gas atmosphere. The Kroll process is being used to product 270,000 pounds per year of zirconium sponge at the Albany, Oregon, Laboratory of the U. S. Bureau of Mines. The Atomic Power Division.of the Westinghouse Electric Corporation produces a very pure zirconium metal in the form of crystal-bar. Some crystalbar is also produced by the Foote Mineral Company. Operation of nuclear reactors at high temperatures has stimulated interest in ceramics as materials of construction. The ceramics possess fine refractory properties, but have very poor mechanical properties. As a result, there have been developments made in the study of mixtures of ceramics and metals, known as cermets. In such materials, it is hoped to combine the mechanical properties of metals

with the refractory properties of ceramics to produce a material well suited to reactor operation. In addition to these new developments in reactor materials, there have been major advances in other phases of metallurgy, resulting from the influence of atomic energy. Nuclear reactor-produced radioisotopes have been used to determine the effect on the constituents of a material undergoing various treatments, such as hardening) quenching, and annealing. These studies were aided by the use of radioautographs to detect the distribution of radioisotopes throughout a material. Since radioactive and stable isotopes perform similarly, the distribution of the stable substance throughout a treated material is also indicated by the radioautograph. Diffusion of atoms within metals, which plays an important role in many metallurgical processes, has been studied, using radioisotopes. Coatings of metallic radioactive isotopes have been applied to the surface of a metal) which is then heat-treated and subjected to various stresses. Subsequent detection of radioactivity in the sublayers of the metal gives an indication of the amount of diffusion. This technicque was used in 1920 to investigate the diffusion of the atoms in lead, using radioactive lead. Such studies were restricted to the use of only a limited number of radioisotopes, but now nuclear reactor-produced radioisotopes of many metals are available for further studies in this field. Another new development in metallurgical techniques is the possible use of specific radioisotopes, which could be formed into special shapes to facilitate the investigation of metal castings. This new radiographic method may eventually supersede the older use of the expensive x-ray equipment required to perform the same tasks. As more personnel are trained in the proper handling of radioactive materials, their use as tools of research will expand considerably. 8.2.3 Medicine Tracer techniques, using radioisotopes, have contributed valuable information to medical researchers investigating the fundamental life processes. In addition, radioisotopes have been used in diagnosis and treatment of diseases. Their use in such a manner is contingent on the preferentlial absorption of particular radioisotopes by certain portions of the body. The blood system has been extensively studied, since samples are easily obtainable and the blood is the main medium for distributing chemicals to all parts of the body. Scientists at Boston University have been studying blood metabolism, using radioactive carbon. Other radioisotopes have been used in the treatment of the blood diseases, leukemia and polycthemis vera, at the University of Chicago and numerous other hospitals. Although not performing final cures in these cases, the diseases have been arrested. Blood volume and the 74

amount of sodium contained in the body have been studied at the Radiation Laboratory, University of California, using radiosodium. Radioactive iron has also been used in dilution techniques of measuring blood volume. Anemia studies have been conducted, using radioisotopes, at Massachusetts Institute of Technology and Brookhaven National Laboratory. Other investigations have been concerned with studies of the blood plasma. Constrictions in the flow of blood have been diagnosed. using radiosodium. Yale Uriversity scientists have been studying the thyroid gland, using radioiodine. Proper functioning of the thyroid depends on an ample, supply of iodine in the body. Overactive thyroid glands have been detected,, using radioiodine, and in some cases, it has been used to treat the condition. Being preferentially absorbed in the thyroid gland, the radioiodine becomes localized there, and the effects of its radiations are restricted to a definite zrea. The radiations emanating from radioiodine have successfully retarded the activity of overactive thyroids in many instances. Cancer research has been underway at a number of institutions, including the University of Michigan, to develop radioactive cobalt-60 as a substitute for the expensive radium. Other experiments at AECoperated National Laboratotires have been performed, using radioisotopes to aid in the understanding of cancer formation. The successes met by using radioiodine for treating overactive and cancerous thyroids have prompted scientists to search for radioisotopes which could travel to other cancerous locations throughout the body. University of Michigan scientists, as well as those from Harvard Medical School and numerous other institutions, have developed techniques for locating brain tumors, using radioisotopes of phosphorus and iodine, which are preferentially absorbed in tumorous tissue. 8.2.4 Engineering The development of nuclear energy has produced new problems to be resolved by engineers. A difficulty arises, due to the lack of experience most engineers have concerning the phenomenon of radioactivity. The engineering colleges and universities of the country are rapidly revising and supplementing engineering programs to acquaint students with this phenomenon. The opinion of educators in such fields favors a continuation of the present engineering curriculum, giving the students a firm background in basic engineering principles, while acquainting them with the problems of nuclear engineering associated with their field of study. No new fields of engineering are expected to develop, since most of the problems confronted in this work may be resolved by extensions of well-known engineering principles. One of the technical problems successfully solved has been the recovery of spent reactor fuels. The nuclear fuels which existed in solution with other substances had to be separated to a degree not attained previously. The combination of chemical engineers and production 75

engineers with the aid of chemists resolved this difficult problem. The high recovery of the valuable element plutonium will aid the competitive position of nuclear power. Due to the high levels of radiation emitted from nuclear processes, engineers have been faced with two severe problems. One problem was how'to reduce the radiation levels down to tolerable levels —which was done with massive shielding; and second, after the massive shielding was in place, a problem of operating equipment through six-foot-thick concrete walls arose. The inaccessibility of equipment made it necessary to develop equipment that would operate remotely and for long periods of time without breakdown. With equipment in such service, problems that would be minor in a more nornal service are major ones in this application. Such a problem would be one of lubrication of moving parts. Another example would be the determination of wear, so that a replacement schedule could be arranged. With the cooperation of mechanical, chemical, and electrical engineers, solutions have been found to many of these problems. The heat generation possible in a reactor has produced other problems, with which engineers have not been acquainted until this time. The thermodynamically efficient transfer of heat at high temperatures is well-known to engineers, but the problem is to remove tremendous amounts of heat from small volumes. Engineers must be concerned with structural, mechanical, and other physical properties of materials of construction and coolants, and in addition must be aware of the nuclear properties of these materials. The final choice of a specific material would be a compromise of all these properties. Not all the effects of atomic energy developments have led to new problems for engineers to tackle. The use of radioisotopes in engineering studies has made significant contributions to the understanding of the mechanisms of many processes. With the use of tracers, the oomponents of a reaction can se followed through all stages of a particular process, demonstrating the effects they have on a reaction. Engineers have found radioisotopes to be most useful in product and quality control. In the production of materials in which impurities cannot be tolerated, the use of radioisotopes has helped to produce an essentially pure product. Radioactive thickness gauges have supplanted older, inferior methods of quality control for the production of such materials as abrasive papers, plastic sheets, adhesive products, and metal foils. The use of thickness gauges depends on the absorption of the radiations emitted from a source located on one side of a moving material. Irregular absorption would cause variations in the machine controls in such a way as to offset the cause of the irregularity. Advantages of this method lie in the ability of the gauge to function without contacting the surface of the material. This permits continaual, instead of intermittent, operation, and prevents damage to materials which could suffer from excessive surface pressures. 76

Tracers have also been used in the analysis of experimental data, and determining the efficiencies of reactants in certain processes. Petroleum engineers and other engineers associated with the petroleum industry have frequently used radioactive tracers in the study of hydrocarbon reactions. There have been many other techniques developed, using radioactive tracers, to aid engineers in the solution of their problems. The final effort of all such work is to produce better products more economically, so that everyone may share in the benefits to be attained by developments in the expanding nuclear energy program. 8.2.5 Special Products The increased use of radioactive materials in industry, and rapid expansion of the nuclear reactor program has seen the development of many products of a specialized nature, manufactured mainly for service in this field. These materials were designed to cope with the problems arising out of the handling and transportation of radioactive materials. There should be applications for these special products in many industrial processes. Chemical analyses using small quantities of radioactive materials are generally performed in hoods or dry boxes. The hoods used are quite similar to conventional hoods employed in working with toxic compounds. Dry boxes are gas-tight containers with glass windows and hand-holes with attached rubber gloves for performing operations inside the box. The use of these devices helps to concentrate any activity in one location. For medium- and high-level activities, cells constructed of concrete, lead, or steel are used in conjunction with remotely controlled manipulators viewed through glass or liquid windows to conduct experiments. Manipulators are available on the market for this type of work. Special types of glass have been developed for use in shielding which will not darken during irradiation. Designs for periscopes have been advanced, as well as mirror systems; and even television has found service in the viewing of operations within radioactive cells. To prevent bodily contamination with radioisotopes, new types of tongs for handling dangerous materials have been designed for special uses. For experiments using high-level amounts of radioactivity within cells, remotely controlled manipulators have been designed. There are several types of such instruments in use today. The problem of transporting radioactive materials has produced many novel designs of carriers and containers. These carriers are usually built with thick lead linings to reduce radiation levels to tolerable levels. Incorporated in the design may be cooling systems that dissipate the heat evolved from radioactive decay. These carriers are regularly used for transcontinentalshipments of radioactive materials. Other new developments have centered around remotely controlled valves of alloy construction. Valves with no packing glands have been developed, that have been used for long periods without leakage or operational failure. The problem of preventing leakage of radioactive 77

materials from pumps has produced a number of different designs of pumps and seals. Special feed pumps have been designed to handle high-temperature radioactive solutions to approximately 1000 psi. There are pumps on the market today with the rotor of the driving electric motor submerged in the process fluid. These canned rotor pumps have no packing glands and have a wide adaptability in pumping solutions where leakage cannot be tolerated. A diaphragm pump is on the market, that has been successful in pumping radioactive solutions without leakage or mechanical difficulties. Stability at elevated temperatures and good heat transfer properties have promoted much interest in liquid metals as coolants in reactors. To handle the liquid metals, several different types of pumps have been developed. Mechanical pumps have been developed, which do a satisfactory job, but have to contend with stringent sealing requirements to prevent contact of the liquid metals with the outside air. A large amount of study has gone into the development of bearings to be operated in liquid metal mediums. The high electrical conductivity of some of the liquid metals has permitted the development of Electromagnetic pumps. All such pumps operate on the same principle as a D.C. motor, in which a currentcarrying conductor at right angles to a magnetic field has a force exerted on it which is perpendicular to both the field and the current. The liquid metal acts as the conductor, and the force exerted on it develops a pressure which is used to transport the metal. The variations in electromagnetic pump designs involve different methods of producing the magnetic field and the current. A new plastic called Teflon was developed exclusively for use in the nuclear energy field. This plastic is a polymer of a fluorinated ethylene, and has shown superior properties at high temperatures and under severe service, such as chevron seal rings, gaskets, and in uses where other plastics are unsuitable. This plastic is now on the market. The success of this plastic has resulted in the development of similar plastics, which are marketed under the name of Kel-F and Fluorothene. In the field of solvent extraction, where good liquid-to-liquid contactors are necessary, pulse columns and mixer settlers have been developed, that are superior to other equipment in certain applications. These contactors should find considerable use in industry in the future. 8.3 Special Hazards Hazards in nuclear energy include radiation and systemic poisons, as well as the normal industrial hazards, such as fire and explosions. That additional hazards existed in this field was recognized at a very early stage. Consequently, all practices and procedures were reviewed to establish where special precautions were necessary. The result of these efforts has been a safety record on the part of the AEC and its contractors, that is considerably better than that of normal industry. With the current safety procedures, a worker is safer 78

working in nuclear energy plants than in most industrial plants. Hazards from radiation have been reduced practically to the vanishing point by adequate shielding of all radioactive equipment, and by the development of special instruments that detect the presence of radiation. These instruments warn the workers before tolerance levels are reached, so they can leave the premises or start decontamination procedures that will reduce or remove the radioactivity. Special monitors have been developed, that continually indicate and record activity in all streams leaving a process handling radioactive material. These instruments can give warnings when radiation exceeds a safe limit, or can operate automatically to stop or divert the stream containing the contaminants. Such equipment acts as a safeguard to prevent contamination of the atmosphere or water streams in the vicinity of a nuclear plant. Light, portable survey instruments have been developed, that are very sensitive to radiation and can detect radioactivity on any equipment in or leaving a plant. These are used regularly in routine surveys throughout areas that might possibly be contaminated. In addition to this, each worker in a danger area wears a personal radiation indicator or badge. These are checked regularly to make sure the individual worker has not been irradiated inadvertently above the tolerance limit. To insure the safety of people outside the plant area, health physics teams regularly tour the surrounding countryside, sampling the streams and inspecting the plants and animals to determine whether any radioactive isotope is accumulating in a given area, plant, or animal. A systematic study of normal industrial operations has resulted in improved methods for doing many tasks. As an example, interlock systems have been developed to prevent a worker from performing a sequence of operations in any manner but by the prescribed safe procedure. Special equipment has been devised for handling very poisonous materials in the laboratory, such as plutnoium, so that the chemist performing the operations never comes into contact in any way with the material being analyzed. Procedures which are similar, but on a larger scale, apply to the actual plant operation. In this field, the greatest industrial participation has been in the development and manufacture of radiation-monitoring instruments, which are used extensively in the program. Many new companies have been formed since 1943) that manufacture and develop instruments exclusively in this field or in the field of tracer analysis, with which such instrumentation is closely allied. With the entrance of nuclear power into the picture, it appears that there will be an increasing demand for such instruments in the future. 79

8.4 Impact of Nuclear Energy on Future United States Economy Electrical power from nuclear energy has already been widely publicized. Considerable emphasis is being placed on studies of the economics of power from such a source. Most studies at the present time have come to the conclusion that a government subsidy, either as a payment for the plutonium produced in processing the spent fuels, or direct support on installation costs, is necessary. It must be kept in mind that these conclusions are reached on the basis of present-day costs. Present-day costs mean equipment that is custom- or hand-built for each particular service, so no allowance is made for economies that could be achieved by multiple or mass production of the same items. In addition to this, many of the factors involved are unknown at this time; and where such conditions exist, the costs can easily be overestimated, It is also significant that, of all the study teams in the field, no two teams have selected the same type of reactor and components. From this, it is evident that the optimum power-producing reactor has not yet been designed. When such a reactor is devised, a further reduction in costs, along with greater efficiencies, can be realized. Another factor that cannot be overlooked is that fossil fuels in this country are being steadily depelted. As the higher-grade fuels are used up, more low-grade fuels must be utilized; and this can be done only at higher costs. What, then, are the possibilities that nuclear power will compete with fossil fuels in the near future? In an address delivered to the twenty-seventh International Congress of Industrial Chemists on September 15, 1954, Walker Cisler and Arthur Griswold discussed some cost data on the St. Clair power plant of the Detroit Edison Company. In this address, entitled "Atomic Energy and the Electric Power Industry", coal costs were given as 35 cents per million BTU, delivered at the plant. Steam at the turbine throttle cost 57.7 cents per million BTU. If it is assumed that turbine and electrical generation efficiencies are such that electrical power can be generated for 0,7 cents per kilowatt hour, fuel costs are then approximately 60 per cent of the total costs. In Palmer Putnam's book, Energy in the Future*, data are given to indicate that coal costs have increased by 1.5 times between 1920 and 1947. Since more coal is being burned now, it appears that coal costs will be up by another factor of 1.5 in ten to fifteen years. By 1970, then, coal costs for the St. Clair power plant should be about 53 cents per million BTU, and power from the plant will cost 0.9 cents per kilowatt-hour, instead of 0.7. Even if the technology of power from nuclear reactors stands still and more economical and efficient nuclear power plants are not designed, it appears likely that power from the nuclear reactors will be competitive with that from fossil fuels in ten to fifteen years. Advances in technology could well cut this time appreciably. A place for nuclear power in future United States economy then seems certain. Published by D. Van..Nostrand Company, Inc., New York 80

Another use of nuclear energy that could affect the country's economy is the heating of buildings. At present, only the largeSt-scale units, heating multiple-office buildings or industrial plants, would be economical. Since high-temperatures are not required, the simplest reactor —such as the selfregulating water boiler —eould be used in a building-heating application. Boiling solution or steam from the reactor could be circulated through an air heater. The heated air could then be carried through ducts to the buildings to be heated. Periodically,:-the "soup" solution in the reactor could be replaced and the spent fuel sent to a central plant for chemical processing. Such a heating unit could be very small and compact. Some of the high costs of the reactor and components: could be offset by smaller charges on space and building requirements that house the reactor. At HEarwell, England, the waste heat from one of the experimental reactors is used in such a manner to heat the office buildings. This unit is of an experimental nature, however, and probably is not competitive economically with conventional heating plants. In very cold regions, such as Greenland or norther Canada, where fuel and transportation costs are high, such heating installations are entirely feasible at the present time. Large propulsion units for ships utilizing nuclear power are, of course, feasible. Two military units have been developed for the submarines Nautilus and Sea Wolf. These units are not necessarily usable for commercial vessels, due to the high cost and special military features. Such units can, however, be the basis for developing economical commercial units. Nuclear power does not appear to be economieally feasible for any but the largest vessels at this time. For about eight years now, studies have been conducted on the feasibility of nuclear-powered aircraft. Design of reactors suitable for propelling aircraft is an extremely difficult problem. Light weight is a necessary criterion; but at the same time, the crew must be shielded in some way by massive shielding, or be placed a considerable distance from the nuclear engine. Once such an airplane becomes technically feasible, there are still some safety problems. Such an airplane obviously could not be landed at a congested commercial airport. It is also distinctly possible that such an airplane would be too large to utilize many of the runways in existence today. While nuclear-powered aircraft may be feasible for special military uses where long range may be of paramount importance, it is doubtful that such an airplane will see common commercial use for many years. Nuclear-powered locomotives have been proposed. Since locomotives are not required to travel extremely long distances without refueling and nuclear power is not competitive on this small scale with oil at the present time, such applications of nuclear power appear to be a development that will not see commercial application for some years. One development that is certain to come, parallel with eleetrical generating plants powered by nuclear energy, i8 the construction of processing plants that will process multiple-type spent fuels. These plants could be designed

to process a number of different types of nuclear fuels, and would be centrally located to several nuclear power plants. Spent fuel would be sent to the processing plant, which would separate the fission products from the spent fuel and return a usable fuel back to the power plant. Fission by-products could be utilized in any of the ways outlined in the previous section. By handling large quantities of spent fuel and marketing all possible by-products, processing costs per unit fuel could be held to a minimum. The impact of new developments in the fields discussed earlier is difficult to estimate. It is certain, however, that the effects will be significant. As an example, the savings in time and expense, by using tracer techniques in chemical analysis and thickness gauging, amounts to $100,000,000 annually. A discussion of these savings is given in Chemical Engineering, October, 1954, published by the McGraw-Hill Publishing Company. The use of carbon-14 tracers in medicine and biology has resulted in developments that were heretofore impossible. Uses of radioactive fission products have barely been touched. It is possible that these materials, now a waste product, will have considerable value in the future, and be a commodity much in demand. 82

9.0 GLOSSARY OF TERMS ATOM - The smallest part of an element that can exist and still retain the physical and chemical properties of that element. A classical picture of an atom is a core, or nucleus, containing neutrons and protons, surrounded by electrons in outer orbits. BETA PARTICLE - A type of radiation emitted from some radioactive elements. It is emitted from the nucleus and has practically no mass and a negative charge. A beta particle has a charge and mass identical with that of an electron. BURN-UP - This indicates the rate of utilization of fissionable fuel in a nuclear reactor. It includes that portion of the fuel fissioned, as well as that undergoing neutron capture without fission to become another isotope. CRITICAL SIZE (CRITTICAL MASS) - The mass of fissionable material that is just sufficient to maintain a self-sustaining fission process. CROSS SECTION - The effective area presented by a nucleus for a particular type of reaction. It is a measure of the probability of the occurrence of a reaction. The cross section varies with the neutron energies. Its measuring unit is the barn (10-24 sq cm, or approximately.154 x 10-24 sq in.) or the millibarn (one-thousandth of a barn, or 10-27 sq cm). ELECTRON - A very small particle having practically zero mass and a negative charge of unity. Beta particles and electrons are identical in physical properties. ELECTRON VOLT - Amount of energy gained by an electron traveling through a potential difference of one volt. GAMMA RAY - A type of radiation emitted from some radioactive elements. It is similar to, but far more penetrating than, x-rays. This radiation makes necessary the heavy shielding of nuclear reactor components. GRAM - A unit of mass or weight. There are 453.6 grams in one pound. HALF-LIFE - This term applies to radioactive materials, and represents the time required for half the original material present to decompose. IONIZATION - A process by which an atom or molecule acquires an electric charge. ISOTOPE - A form of an element which has all the chemical properties of that element, differing only in weight. For example, U-233, U-235, and U-238 are all isotopes of uranium. 83

MASS UNIT - Unit based upon one-sixteenth of the weight of an oxygen atom taken as 16.00000. MEGAWATT - One million watts, or 106 watts. MOLECULE - Smallest quantity of a compound that can exist by itself and have all the chemical and physical properties of the compound. NEUTRON - One of the components of the nucleus. A neutron has a mass of one (the same as a hydrogen atom) and a zero charge. NEUTRON CAPTURE - The nucleus of an element can absorb a neutron to become another isotope of the element with a unit higher atomic weight. This isotope then usually decays to another element. A typical neutron capture can be written as: 235 + n - 92U236 where U-236 is the new uranium isotope, formed from U-235 by neutron capture. NUCLEUS - The central part of an atom, around which the electrons move in their orbits. A nucleus is composed of protons with a positive charge and neutrons with zero charge. PROTON - One of the components of the nucleus of an atom. A proton has a positive charge that is equal, but opposite in sign, to the charge on the electron. The proton and neutron both have a mass of unity. RADIOACTIVITY - A process by which an atom having an unstable nuclear configuration releases energy in the form of alpha (a type of radiation which is essentially a helium nucleus having four mass units and a positive charge of two), beta, or gamma emissions, as the atom achieves a more stable state. Usually, an atom of a new element is formed in the process. 84

UNIVERSITY OF MICHIGAN 31111111111111111111111111111111 3 9015 03482 8791