United States Patent (19) 11 Patent Number: 4,721,596 Marriott et al. (45) Date of Patent: Jan. 26, 1988 54 METHOD FOR NET DECREASE OF New Scientist, 7/77, pp. 14-16, Steinberg. HAZARDOUS RADIOACTIVE NUCLEAR CONF-760622-3, "Actinide Transmutation Studies: A WASTE MATERALS Review”, Croff, 6/76, pp. 1-14. (75) Inventors: Richard Marriott, Detroit, Mich.; BNWL-1900 (vol. 1), 5/74, Schreider et al., pp. Frank S. Henyey, San Diego; Adolf 1.42-1.45, 1.67. R. Hochstim, La Jolla, both of Calif. Huse et al., "Fusion-Fission Energy Systems: Some Utility Perspectives', ERDA-4, Dec. 3, 1974, pp. 73 Assignee: Perm, Inc., La Jolla, Calif. 27-61. (21) Appl. No.: 613,013 Tenney, “A Tokamak Hybrid Study," CONF-760733, pp. 71-80. 22 Filed: May 22, 1984 Rose et al, "Tokamak Antinide Burner Design Study', US-USSR Symposium of Fusion-Fission Reactors, Jul. Related U.S. Application Data 13-16, 1976, pp. 91-115. 63 Continuation of Ser. No. 455,046, Jan. 3, 1983, aban 'Alternatives for Managing Wastes From Reactors and doned, which is a continuation of Ser. No. 100,658, Post-Fission Operations in the LWRFuel Cycle', ER Dec. 5, 1979, abandoned. DA-76-43, vol. 4. 51) Int. Cl." ...... G21G 1/02; G21G 1/06 "A Radioisotope-Oriented View of Nuclear Waste 52 U.S. Cl...... 376/189; 376/169; Management', A. F. Rupp, ORNL-4476 (1972). 376/170; 376/184; 376/186; 376/158 "A Re-Examination of the Permanent Disposal of Ra 58) Field of Search ...... 376/184, 189, 158, 170, dioactive Waste', Marriott et al RIES 75-106 (1975). 376/146, 169, 186 "Advanced Waste Management Studies Progress Re port 8, BNWL-B-223 (1973), Editor A. M. Platt. (56) References Cited "High Level Radioactive Waste Management Alterna U.S. PATENT DOCUMENTS tives”, BNWL-1900, vol. 4 (1974). 2,837,475 6/1958 Newson . "Neutron-Induced Transmutation of High-Level Radi 3,175,955 3/1965 Cheverton. oactive Waste', ORNL-TM-3964, H. C. Claiborne 3,255,083 6/1966 Klahr . (1972). 3,276,963 10/1966 Pearce et al. . Primary Examiner-Harvey E. Behrend FOREIGN PATENT DOCUMENTS Attorney, Agent, or Firm-Schwartz, Jeffery, Schwaab, 620485 5/1961 Canada ...... 376/158 Mack, Blumenthal & Evans 224.9429 5/1974 Fed. Rep. of Germany . (57) ABSTRACT 802971 10/1958 United Kingdom. 1035078 1/1960 United Kingdom...... 376/189 A method for decreasing the amount of hazardous radi oactive reactor waste materials by separation from the OTHER PUBLICATIONS waste of materials having long-term risk potential and Nuclear Eng. Int., vol. 23, No. 266, 1/78, pp. 40-43, exposing these materials to a thermal neutron flux. The McKay. utilization of thermal neutrons enhances the natural Nuclear Technology, vol. 42, 1/79, pp. 34-50, Berwald decay rates of the hazardous materials while the separa et al. tion for recycling of the hazardous materials prevents Neclear Technology, vol. 42,2/79, pp. 180-194, Parish. further transmutation of stable and short-lived nuclides. Trans. ANS, 6/77, pp. 70, 71, Parish et al. Trans ANS, 6/77, pp. 293,294. 15 Claims, 38 Drawing Figures
NEUTRONS WASTE TO MANTAN PRODUCTs NEUTRONS CHAIN REACTION
FUTURE POSSILITY NEUTRONS FOR NSURONS FROMNO FISSION SOURCE TRANSMUTATIO (e.g., FUSON)
HIGH FLUX
TRANSMUTATION
CHEMCAL/PHYSICA WASTE SEPARAON ReATMENT CYCLE "GOOD" SUBSTANCES "BAO" STORAGE SUBSTANCES
DISPOSAL U.S. Patent Jan. 26, 1988 Sheet 1 of 32 4,721,596
FISSION
NEUTRONS WASTE TO MANTAN ENERGY PRODUCTS NEUTRONS CHAIN REACTION
FUTURE POSSIBILITY NEUTRONS FOR NEUTRONS FROM NO FISSION SOURCE TRANSMUTATION (e.g., FUSION) HIGH FLUX
TRANSMUTATION
CHEMICAL/PHYSICA WASTE SEPARATION TREATMENT CYCLE
"GOOD" SUBSTANCES BAD
STORAGE SUBSTANCES
DISPOSAL fig. 1 U.S. Patent Jan. 26, 1988 Sheet 2 of 32 4,721,596
WOOLN||NOCHOSILNE
U.S. Patent Jan. 26, 1988 Sheet 3 of 32 4,721,596
BETA DECAY
SOTUPE NEUTRO YELDCAPTURE BETA DECAY HALF LIFE IN HOURS NEUTRON CAPTURE CROSS SECTION IN BARNS
U.S. Patent Jan. 26, 1988 Sheet 4 of 32 4,721,596
O
IO IO IO IO4. IO IO IO IO IO 9 ty2 (YEARS)
fig. 5 TIME TO DECAY TO ACTIVITY OF HALF THAT OF 238 AS A FUNCTION OF HALF LIFE THE DOTS ON THE CURVE REPRESENT FESSION PRODUCTS U.S. Patent Jan. 26, 1988 Sheet 5 of 32 4,721,596
OO 7 7 FISSIONS NEUTRON RADATIVE CAPTURES CAPTURES
7 NEUTRONS
27 NEUTRONS
NEUTRONS ABSORBED N U238
NEUTRONS ABSORBED IN 2OO MODERATOR FISSION PRODUCT
NUCLE NEUTRONS LOST FROM REACTOR
35 65 HIGH RSK STABLE OR POTENTIAL SHORT LIVED NEi For NUCLE NUCLE TRANSMUTATION fig. Ei U.S. Patent Jan. 26, 1988 Sheet 6 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 7 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 8 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 9 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 10 of 32 4,721,596
O O 6
O. Ol O 2O 3O 4O TIME (THOUSANDS OF HOURS ) fig. U.S. Patent Jan. 26, 1988 Sheet 11 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 12 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 13 of 32 4,721,596
O. O 2O 3O 4O 5O TIME (THOUSANDS OF HOURS) fig. 11 U.S. Patent Jan. 26, 1988 Sheet 14 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 15 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 16 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 17 of 32 4,721,596
1 U.S. Patent Jan. 26, 1988 Sheet 18 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 19 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 20 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 21 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 22 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 23 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 25 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 26 of 32 4,721,596
OOIO|||° BW||WOH+NOISSI-,(S}}[\OH)
(NOSSld OO 3d U.S. Patent Jan. 26, 1988 Sheet 27 of 32 4,721,596
N ISOTOPE N SEPARATION
Cs (STABLE)
OOO 200O 3OOO 4OOO 5OOO 6OOO 7OOO TIME (HOURS) fig. 18 U.S. Patent Jan. 26, 1988 Sheet 28 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 29 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 30 of 32 4,721,596
O.4 AMOUNT OF Sm'
HIOO MARGINAL NEUTRONS/REMOVAL OF Sm
AVERAGE NEUTRONS/REMOVAL OF Smol
O 2O 3O 4O TIME (HOURS U.S. Patent Jan. 26, 1988 Sheet 31 of 32 4,721,596
U.S. Patent Jan. 26, 1988 Sheet 32 of 32 4,721,596
- l &
3
S.
rf) o S. CN O O O O O O O O O (NOSS- OO 3d) LN? OWW 4,721,596 1. 2 would permanently remove the wastes by transporta METHOD FORNET DECREASE OF HAZARDOUS tion by rocket into the sun. Two major problems face RADIOACTIVE NUCLEAR WASTE MATERIALS this technique. First the cost, and second, but more significant, there is the possibility of vehicle failure This application is a continuation of application Ser. 5 within the atmosphere leading to a highly dangerous No. 455,046, filed 1-3-83, now abandoned, which is a level of radioactive contamination. continuation of application Ser. No. 100,658, filed on A more attractive technique involves the direct trans Dec. 5, 1979, now abandoned. mutation of the dangerous waste materials by neutron BACKGROUND OF THE INVENTION bombardment into innocuous materials, or at worst 10 short lived radioactive species. Such a transmutation 1. Field of the Invention can be achieved, for example, by recycling waste prod The invention is in the field of nuclear waste control ucts back into the reactor which produced them. Such and is particularly directed toward the elimination of nuclear transformations have been discussed in the liter long-lived radioactive nuclides of nulcear reactor ature but have been found only applicable for effective Waste. 15 elimination of the actinides produced by neutron cap 2. Description of the Prior Art ture, e.g., "Advanced Waste Management Studies The difficulties encountered in attempting to safely Progress Report', 8, BNWL-B-223 (1973); H. C. Clai dispose of radioactive wastes generated by the fission borne, "Neutron Induced Transmutation of High-Level process in nuclear reactors is probably the largest single Radioactive Wastes', ORNLTM-3964, 1, 24; and cause of public resistance to the construction of nuclear 20 "High-Level Radioactive Waste Management Alterna power stations. A decade ago it was liberally estimated tives', 4, 9, BNWL 1900 (1974). The applicability of that 200,000 megawatts of nuclear generated electricity transmuting long-lived fission products as well as the would be available by 1980. Today this expectation is actinides by neutron capture in reactors has not been down by one half. A major argument against permitting regarded as practical since such a procedure reputedly the further spread of nuclear power involves concern 25 produces more long term waste than it removes. over methods proposed for disposal of the nuclear waste products. Present methods of disposal of nuclear SUMMARY OF THE INVENTION waste, which may be in the gaseous, liquid or solid state It is therefore a general object of the invention to consist either of dilution and dispersion or storage. In reduce to amount of radioactive waste and in particular the first approach radioactive gases or liquids are di- 30 fission products in nuclear reactors so that time storage luted with large volumes of air or water to reduce the requirements may be reduced from those required for activity per unit volume to an allegedly safe level and natural radioactive decay. released into the environment. In the second use, radio The invention may be characterized as a method of active materials are stored in the containers in the increasing the rate of transmutation of radioactive nu ground or under the sea. With adequate safeguards, 35 clear waste materials in excess of their natural decay storage for about 30 years suffices to remove the harm rates for the more rapid conversion to stable nuclides. from relatively short-lived radioactive nuclides, but the The method comprises the steps of (a) extracting the situation is quite different for the long lived wastes. nuclear waste from the reactor fuel, either continuously Fortunately, the majority of the fission wastes have or periodically, (b) separating the waste into selected half-lives less than one year, which means that at worst 40 components of different constituents, (c) storing those they must be stored for 33 years to be reduced to 10-10 components composed of stable nuclides or of short of their original amount. However, eighteen fission lived nuclides which naturally decay into stable nu waste products as well as all the actinide waste products clides, (d) exposing those components containing long have half-lives greater than one year, but less than 100 lived high risk potential nuclides to a high flux of ther years, and it is these products that pose the long term 45 mal neutrons in order to induce nuclear transmutations, storage problem. To ensure that long lived waste prod (e) further separating of the waste after exposure to the ucts are kept out of the biosphere until they become neutrons, and repetition of steps c, d, and e for transmu harmless-involving periods of hundreds of thousands tation of the long lived radioactive waste into stable or millions of years-present proposals involve burial in nuclides, or to short lived nuclides which rapidly decay geological salt formations or other formations such as 50 to stable nuclides. granite, quartzite, tuff (welded volcanic ash) and shale. The burial solution to the waste problem is based on BRIEF DESCRIPTION OF THE DRAWINGS the assumption that the geological formation will re These and other objects of the invention will become main stable for the necessary containment period. While clear in relation to the following specification taken in this assumption is reasonable for plutonium, for exam- 55 conjunction with the drawings wherein: ple, it is not evident for the longer lived wastes includ FIG. 1 is a block diagram of the overall waste trans ing the fission products Pd 107, Tc99, I129, CS135, and mutation method and system in accordance with the Zr'93, as well as the actinides. invention; In view of the extreme hazard that would be created FIG. 2 is a block diagram of a preferred embodiment if these materials were to be released into the biosphere, 60 of the separation/irradiation treatment cycle; there is a strong and growing resistance to the "bury it FIG. 3 is an illustration of the format utilized to de and forget it' philosophy, and this opposition has now posit the decay/transmutation chain in general; developed to the point of significantly slowing the FIG. 4 illustrates a proton of the decay/transmuta growth of nuclear power. It is therefore most desirable tion chain for a specific nuclide; if a method could be found to completely eliminate the 65 FIG. 5 is a chart of the fission fragment decay times noxious radioactive wastes from the environment. as compared to one-half the decay activity of U238; Two methods have been suggested for such a final FIG. 6 is a block diagram illustrating neutron econ solution to the waste problem. Extraterrestrial disposal omy in the fission reactor process; 4,721,596 3 4 FIG. 7 represents the decay/transmutation chain for Plutonium, and/or Thorium, are separated into various Se79; components, each component comprising one or more FIG. 8 represents the decay/transmutation chain for different elements of the waste nuclei. This separation is Kr85 and Sr90; either chemical or physical or a combination of the two FIG. 9 is a chart showing the removal of Krš as and may further include isotope separation. In principle, compared to its natural decay; isotope separation, as for example employing a mass FIG. 10 represents the decay/transmutation chain for spectrometer, could be utilized for separation of all Zr'93; isotopes. Economic considerations would, however, FIG. 11 is a chart showing the removal of Zr' for dictate primarily a combination of chemical and physi both chemical and isotope separation; 10 cal processing. Those "good" components which in FIG. 12 represents the decay/transmutation chain for clude only short-lived and stable elements and which do Tc99; not include long-lived hazardous radioactive substances FIG. 13 represents the decay/transmutation chain for are stored to allow the decay of short-lived substances. Rul06 and Pd 107; Those "bad' components containing long-lived radio FIG. 14 represents the decay/transmutation chain for 5 active substances are exposed to a high flux of neutrons Sn 126 and Sb.125; in order to induce transmutation. After a certain amount FIG. 15 represents the decay/transmutation chain for of exposure, these wastes are recycled through the sepa Sn 126 and I129; ration/irradiation loop. FIG. 16 represents the decay/transmutation chain for The high neutron flux may be produced by any of a the Cesium isotopes; 20 number of methods that are often referred to as flux FIG. 17 is a graph showing the amount of Cs135 and . trapping. These methods allow the flux in some regions Cs133 as a function of Xenon removal time after fission; of the fission reactor to be significantly higher than in FIG. 18 is a graph showing the amount of Cs13, other parts, making use of the strong decrease of cross Cs134 and Cs135 as a function of time; sections of increasing neutron energy from thermal to FIG. 19 represents the decay/transmutation chain for 25 MeV regime neutrons. Flux-trap reactor designs are Pm 147 and SmI51; described in, for example, U.S. Pat. Nos. 3,255,083, FIG. 20 is a graph showing the removal of Sms as a 3,341,420; 3,276,963; 3,175,955; and 2,837,475. function of time; Alternatively, the high flux may, in the future, be FIG. 21 represents the decay/transmutation chain for produced independently of fission reactors, most nota Eu 154 and Eu 155; and 30 bly by fusion reactors. In this case economy of reaction FIG. 22 is a graph showing the time development of utilization is not critical as copious supplies of neutrons EulS4 and Eu 155. can be produced with little accompanying radioactive waste. FIG. 1 illustrates the inventive method gener DETAILED DESCRIPTION OF THE ally. PREFERRED EMBODIMENTS Where reaction economy is an important factor i.e., Overview fission produced sources, the preferred chemical/physi As used herein, the term transmutation may be de cal separation techniques is to be carried out as a two fined as the change of one nuclide into another nuclide stage process as illustrated in FIG. 2. of the same or a different element by any nuclear pro In stage 1, reactor products are separated into com cess, natural or artificial. A beneficial transmutation can 40 ponents designated, for the sake of illustration, A, B, D, be defined as any transmutation which leads, or is part and D. Each component, once separated is maintained of a sequence of transmutations which leads, in a rea in a separate channel isolated from other components sonably short time, from a long lived radioactive nu and fed to the high flux region. After transmution in the clide to a stable nuclide. high flux region the output of any given channel will In accordance with the principle of the invention, 45 generally contain some smaller amount of the original radioactive waste materials are re-cycled in a region of component remaining together with additional ele a high-flux of thermal neutrons to permit neutron in ments. These additional elements may be "good' prod duced transmutation. Chemical and/or physical and/or ucts designated G1, G2. . . Gé, or other components isotope separation of the waste may be performed both which are long-lived and require futher processing. The prior to and/or after neutron irradiation. This separa 50 original component of each channel is thus separated in tion has several benefits: stage 2 from these additional elements as illustrated in 1. It minimizes the waste of neutrons which would FIG. 2. The recycling then occurs from the output of occur in the nonbeneficial transmutation of a stable the stage 2 separation to the high flux region. Isotope nuclide into another nuclide. separation may be part of stage 1 and/or stage 2 separa 2. It minimizes the production of long-lived radioac 55 tion. Further, a specific rest stage may be provided tive nuclides from transmutation of stable nuclides. before and/or after exposure to the neutron flux to 3. It minimizes the amount of material that has to be permit (3 decay where desired prior to further neutron handles in the exposure to the high flux. exposure. 4. It maximizes the beneficial use of the available The choice of separation/irradiation strategies de neutrons in reducing the radioactive waste hazard. 60 pends, in addition to economic and chemical consider A block diagram of the process in accordance with ations, on the transmutations possible. FIG. 3 shows a the invention is shown in FIG. 1. U235 or other fissile general format utilized in describing the decay/trans material undergoes fission, splitting into various fission mutation sequence and FIG. 4 illustrates, as an example, fragments and producing neutrons. Some of these neu a portion of a chart of some nuclides illustrating the trons are used up in maintaining the chain reaction, 65 transmutation possibilities. Natural (3 decay transmuta while others are used in transmuting the waste. The tions change a nuclide into another shown directly waste products, including the fission fragments and above it, while artificial neutron induced transmutations actinides produced by neutron irradiation of Uranium, take a nuclide into another immediately to the right. a. 4,721,596 5 6 and (3-- decay are not significant, and for simplicity, 4. It is descended from neutron-rich nuclear species only one isomer of each nuclide has been considered. by either (a) (3 decays or (b) a combination of 3 decays The values shown on the vertical lines connecting nu and neutron absorptions. However, (3 decay chains clides are the half-life of the transmutation in hours, through nuclides of half life greater than 10 years are while the values on the horizontal line are neutron not considered. Exceptions to this rule are present at the cross-sections in barns. 10 parts per billion level in the waste. Fission yields per 100 fissions are also given in the 5. The excited states Sn 121m, Hol66m and Cd113m are chart. The direct fission yield is almost completely to excluded. neutron rich nuclides not shown, which would occur A conservative level of activity at which a substance below those shown. These neutron rich nuclides rapidly 10 can be considered nearly safe is half the activity of an undergo a series of 3 decays, as tabulated by Rose, P. F. equal amount of U238. This criterion is in agreement and Burrows, T. W., ENDF/B Fission Product Decay with the cutoff in half lives of 1010 years, twice the half Data, August 1976, BNL-NCS-50545 (ENDF-243), to life of U238 (and also twice the age of the Earth). The those nuclides which are illustrated on the chart. The required storage time as a function of half life is shown yield shown on the charts of FIGS. 3 and 4 is therefore 15 in FIG. 3, with the bad nuclides indicated by dots. For the same yield as the direct fission products of the same our one-year cutoff in half life, this criterion requires a atomic weight. The document Permanent Elimination of storage time of 33 years. The lower group of bad nu Radioactive Wastes by Nuclear Transmutation, Physical clides requires up to 3,000 years of storage, while the Dynamics, Inc. PD-LJ-79-204, August, 1979 by Frank upper group requires at least a million years for every S. Henyey, the whole of which is incorporated herein 20 nuclide in that group, and up to 1/30 the age of the by reference, gives further details of the assumptions earth. and computer analysis given herein. Preliminary Theoretical Considerations Sr'90 is a long-lived radioactive nuclide which is de The transmutation process must satisfy at least three sired to be removed. Therefore, the transmutation from criteria: (1) it must consume less energy than was pro Sr90 to Sr'91 is a beneficial transmutation. Sr91 naturally 25 duced when the waste was created. (2) it must generate transmutes in a short time to stable Zr'91. On the other of itself less hazardous waste than that destroyed, and hand, the other neutron induced transmutations shown (3) it must eliminate waste materials at a rate significatly are not beneficial and must be minimized by choice of greater than their natural decay rate. Previous studies the separation/irradiation loop. Y39--Y90, for example, reported in ERDA-76-43, vol: 4 indicate that only neu does not involve long-lived nuclides at all and therefore 30 tron absorption processed can satify the first criterion. the induced neutron transformation simply wastes neu The major source of neutrons at present are the fission trons. Sr9->Sr90 not only wastes neutrons but also pro power reactors themselves. Therefore the issue of the duces a long-lived nuclide. As described more fully second criterion is whether the number of neutrons hereinafter, the Sr9 is allowed to naturally transmute to produced in the power reactor is sufficient to transmute Y89 prior to insertion of Sr into the high neutron flux 35 all or a substantial amount of the long lived waste pro region. Y is then chemically separated from the Sr to duced along with those neutrons. The employment of prevent its otherwise neutron usage, and the Sr is ex chemical and/or physical separation of waste contained posed to the high neutron flux to transmute to Sr90 to in this invention is aimed primarily toward the satisfac Sr91. tion of the third criterion. In the case of the actinides, 40 both as a consequence of their large neutron capture Table 1 lists 18 long-lived radioactive fission products probabilities and because their final removal by fission is of concern. These “bad” nuclides are broken-up into accompanied by regeneration of some of the neutrons two groups, the first group having half-lives less than absorbed, all three criteria can be met. However, when 100 years, and the second group having half-lives the fission wastes are included, earlier studies cited greater than 30,000 years. In addition, there are actinide 45 above, not incorporating the principles of the invention, wastes not listed. In reference to FIG. 2, there may be concluded that the second and third criteria could not up to 18 separate separation/irradiation loops for the be met. The invention is directed toward meeting all fission products and an appropriate number of loops for three criteria. the actinides, one loop for each substance. Production of Safe Waste Products The "bad' nuclides considered for elimination are 50 With regard to the second criterion, it is convenient listed in Table 1 and are defined primarily by the to perform the transmutation in the power reactors amount of radioactivity they are responsible for in the themselves. Fission of an average U-235 nucleus gener waste, after the waste has been stored for a certain ates a certain amount of waste and a certain number of length of time. Their half-life is not too long, else they neutrons. The question in satisfying the second criteria provide very little radioactivity. Their half-life is not 55 reduces to whether these neutrons are sufficient to too short, else they decay during the storage period. transmute the waste produced. They must be present, or at least have the possibility of More specifically, one may consider the fate of the being present, in a sufficiently high concentration to neutrons produced from 100 fissions of U235, as illus contribute significant radioactivity. trated in FIG. 6. All neutrons are considered to be With these qualitative criteria in mind, the following 60 thermalized. Of the 244 neutrons produced, 117 are somewhat arbitrary quantitative definition of a bad required to maintain the chain reaction, causing 100 fission product nuclide is utilized: additional fissions and 17 absorptions without fission. 1. Its half life is greater than 1 year; The remaining 127 neutrons are absorbed in various 2. Its half life is less than 1010 years; ways including being absorbed in U238, producing acti 3. Its atomic weight is between A = 72 and A= 167, 65 nide waste and ultimately more fission waste, and being since these are the limits of fission product compilations, absorbed in the moderator and structure of the reactor. and the yields outside this range are below the part per Those remaining are available for waste transmutation. billion level. Of the 200 fission products there are 35 long-lived radi 4,721,596 7 8 oactive nuclei (plus those from fission of Plutonium and two terms determine its gain due to the decay or trans actinide wastes). This waste requires at least 35 of the, at mutation of other species. most, 127 neutrons in order to accomplish the transmu The solution of this equation has the form tation. Without the principles of the invention, many more than 35, and even more than 127, neutrons will be 5 required. V7(t) - X -CZ.4:Z.4', ... e--AZ"...it To establish whether there are sufficient neutrons to Z. TZ 37 eliminate the associated waste products, it is necessary A's A to study the transmutation-decay chain information on all nuclides which are placed in the high flux region. O where AZ4' = a Z24' -- ozd'db and the C's are deter The most important such nuclides are the isotopes of mined by the initial amounts and by substituting this those elements including the long-lived radioactive solution into the differential equation. fission products of which the eighteen most important In detail, the C's are given by: radioactive nuclides are listed in Table I. The nuclide (1) For Z.A not both equal to Z". A symbol and half-life are listed in the first two columns. 15 The cross sections which determine the neutron induced transmutation rates are listed in the third col umn. The approximate amounts (per 100 fissions) in the nuclear waste is given in column 4. Column 5 gives the WZ,4' name of the element. A computer program, WASTE, listed in appendix A 20 (where C's which don't obey the conditions was utilized to study the chains for all eighteen fission Z's ZA's A are zero). waste products. This program constructs a solution of a (2) For Z.A=Z"A" large set of coupled differential equations describing the transmutations. The form of these equations is that the time rate of change of any nuclide is equated to a sum of 25 up to four terms as follows: 1. The decrease of the nuclide by natural decay. These substitutions are carried out in order of increas 2. The decrease of the nuclide by neutron-induced ing Z and increasing A. Thus the lowest nuclide in a transmutation into another nuclide. 30 chain, which will occasionally be a bad isotope, has its 3. The increase of the nuclide from natural decay of amount decreased following an exponential curve: another nuclide. 4. The increase of the nuclide from neutron-induced transmutation of another nuclide. Nzac) = Nzco e (c-o-o-Zo-hot The computer program further allows initial separa 35 tion and periodic separation between exposures to a The effective half life for removal is high thermal neutron flux. A strategy for each nuclide is presented which is sufficient to meet the three criteria for successful transmutation. ln2 In utilizing fission reactors, it is possible that (1) each 'ZA + ZAodb reactor is responsible for precessing its own waste or (2) 40 several "power' reactors send their waste to one "trans These effective half lives of the bad nuclides are com mutation' reactor. In as much as neutrons are in short pared to the natural half life in Table 2. The effective supply, and the second alternative is most probably not flux is taken to be 1016 neutrons/cm2 sec. viable since it wastes the neutrons. The first possibility, Another case of importance is that of a nuclide which of course, allows the exchange of waste between differ 45 as a lower nuclide in the chain with a smaller value of A. ent reactors; one, for example, might handle all the Let us take, for example, a nuclide (ZA) accompanied cesium while another handles all the zirconium, with by a lighter isotope (Z, A-1) such that AZA-1
TABLE 4 ELEMENTS WITH SIGNIFICANT AMOUNTS OF STABLE 40 ISOTOPES REMAINING AFTER PROCESSING. SHOWN ARE THE NUMBER OF NEUTRONS (NORMALIZED TO 100 FISSIONS). NEEDED TO TRANSMUTE ALL THE STABLE ISOTOPES TO OTHER ELEMENTS. Bad Neutrons required Isotope to transnute 45 Element Left stable isotopes Kr O7 6.0 Sr 25 3.2 Zr 50 23.6 (1) Pd O35 1.3 Sm O13 14.8 (2) SO Haeranterms-ser-masses (1) Zr: case a (no Zr' in initial waste.) (2) Includes Sm transmutation of Pm.
55
60
65 4,721,596 21 22 CONTROL PROGRAM FOR ASTE
CONTROL PROGRAM FOR WASTE PRINT OOO 1000 2 ORAT ( /INPUT / CHOOSE DATA ONE OF THE Follon OPTIONS:NS: Af :3: INPUT CHAINS OF DECAY / TRANS MuTATION / :: INPUT A MOUNTS OR CHEMICAL PROCESSING sy : CAL CULATE TRANSITION COEFFICIENTS 6 5 CAL CUUA TE A MOUNT S AS A FUNCTION OF TIE / 7 6. OUTPUT DATA TASE of 8 7 EXIT ) REAO (1 a ERR = 1 N GOTO (il 12 15 14, 1516, 7), N GOTO CAL INDATA GOTO 2 CALL IN CHA GOO S CALL IN CASE GOTO 4 CALL ASE GO TO - S CAL MAN GOO 16 CALL NUCL GOTO 17 CALL, EXT NO SUBROUTINE ASTE
SUBROUTINE WASTE ASTE PROGRA COMPUTES TRANSTION CO EFFICIENTS DIENSION ACO (8 O 8G) 1 A LAM (50) BSI G (50 BSI GF (50) 2Chi R (50) DIENS ON HALF (25G SIG (25 O S GFS (25 O) OMENS ON G CO (8 O 8 O) COMMON / AREA AC. R. COMMON / AREA 5./NAME COMMON / CO/CO REAL tre. NAME (50) NAMEN ( 2) INTEGER AT NUM (250 ) ATT (250) NME (250) NAT (50) A (50) 2 N (SO) S INSER SYSCOMX KEYS. F s NSERT SYS COMXERRD F CALL SRCHSS (KS READ DATA 4 I y IC) OO O2 NOT a .250 READ (5, 1 Oc ) J, ATNUM (NFOT), NME (NTOT), A TWT (NTOT) 2 THALF (NTO) SIG (NTO). SIGFS (NTO) FORMAT (2 A2 5 SEl A ) F (JEGO GOTO 1 OS O2 CONTINUE 13 NT ON TO as CALL SRCHSS (KSCLOS DATA A IT C) 3. OS PRINT 1 OO2 1 02 FORMAT (M NPU FLUX IN UN I TS OF NUMBERMS ECONO ) S O6 READ (1 a ER RES 05)ZZ ZEZZA 1 E24 PRINT 0. o O FORMAT ( / O INPUT FILE NAMEP) S 14 READ (1 70 O2 ER RES15) NAMEN ( 2) LENGTHEB CALL SRCHSS (KSRT NAMEN (2) ENGTH 2. IT I C) 4,721,596 23 24 R. E. (6 SO O2). ZZ O2 FORMAT (2 47) CAL SRCHSS (KS READ CHA NS 6 I C ) 5 O. READ (7 Ol NPAR PAR AXN MAX F (NPAR, N E O GO TO 5 OS FORMAT ( 5 X S 2 X 3 4X 3 2X S ) CALL SR CHSS (KS CLOS CHA INS S C) ZE ROO ZERO 2 O. R. E. (6 SC OS X 2. R O ZERO ZERO 2 ERO CA. SR CHSS (KSC OS NA. E. N. ( 2) ENGTH 2 C) PRIN G2 NAMEN ( 2) FORMAT ( / TRANSI ON COFF f S HAVE EN ENT RED 2 IN FILE A8 P R N T 6 Ol FORMAT ( / 9 ST OP2 ) REA O ( 6 O2) X FORMAT (A F (X, EG ) GO TO OS R U R N O DO O4 = NTO F (ATNUM ( ) NPAR) GO TO O. A F (AT ( ; ) LT IT PAR) GO TO 04 F ( ( ATNU M ( ), GT MAXN) OR ( (AT NUM ( I ) . EG MAXN) is AND e ( A VT I ) . GT MAX GOO O 5 F (A G MAX) GOTO NEN 4 N AT (N = A T Nu M ( . ) A N A ( ) N (N) : ENCODE (8 OO. NAMEN) N A N) NM (, ) A N. NAME ( N N AMEN ( ) i 100 FORMA ( 3 A2 S ALAM (N) Ef AF ( ) BSI G (N) SI GC I) BSI GF N S S I GFS ( . ) F (AT NUM (I) EGi AXN ) - AND. (A TWT ( ) - EO MAX GOTO i 05 O A CONTINUE PRIN 1.003 OOS FORMA (A DATA FE DOES NOT CONTA N PAREN AND 2 /OR AX 2 OR A TO O LARGE' ) w CAL EX CON NUE D S N OO 3 JEl N ACO ( I ) 200 PH (S6 O O ) to Z. XLG2 AOG (20) 5 N XL A-20 F (ALAM (t) .NE O - ) X-AM =XLOGM A-AM ( ) ABS-CBSG ( ) PH ABSF 8S GF ( ) Pht CHR ( ) is a X AM 0 X ABS-X. A BSF F (X ABS N E O - AND A (L.) NEMAX ACO (t + i - ) 2XABS IF (XL AME GO OR NAT ( t ) Q MAXN GOTO 5 PE4 DO 6. KEP N F ( C N AT ( , ) NE N A ( ) ( . ) OR ( A (rc NE A. ( . ) ) GO TO 6 ACO (K X. A d GOTO 5 CONTINUE PRINT & NAME ( ) OO & FOR AT ( / AT A FILE IN COMPLETE A 8 GO TO 5 5 G5 PR NT 3.5 O GO TO CS 5 PR 35 GO TO 14 4,721,596 25 26 35 C F OR MA ( t HAT 2 ) 5 CO W T UE 7 CA L X MA ( A CON) 2 OO 2 El "DO 2 JE 1 F ( 0 CO ( ) J ) . C. C. - ) GO TO 21 R T E (b. OS ) I ( , ) N ( , ) (J) , CO ( J) SU3 ROUTINE MAIN DIENS ON T MAT (25 O 4 O ) EV (250) OAM (250) 2 TM ATD (25 O 40) AMT (250) DUMP (25G) V (250) E V 2 (250) REAL 8 ISO FILE CD ON AL I MITS/N 0 , Nhl GH NBAD NBN NBB BLB NL , BBL COMMON / TMATS/T MATS (250, 4 O) COMMON/T OPES/A (250) I Z (250 ) , ISO (250) N, ALOSS COMMON/ TO SMAN FISS S INSERT SYS COM KEYS. F S INSERT SYS COM > E R RDF CA SRCHSS ( K S DELE OUT 3 O T I C ) CALL SR ChSS (KS WR IT V OUT 3 4 I I C) L ENG THE8 20 PRINT O29 1 O29 FORMAT ( / INPUT NO NHIGH ( ) READ ( ER RE.200) NL 0 NHI GH PRINT 1 000 000 FORMAT ( At CHOOSE OPTION FOR TRANSIT ON MATRIX FOR I. R RAD I A ON 2 / ... NO R RAD I ATION DT RE O / 2 CAL CUA TE THE ARE XV / 3 S INPUT THE MATRIX A 4 LEAVE AS IS ) 2O2 READ ( ER RE2 C20 ) IOP GO TO (61 62 63 64 ) IOP 2 O2O PRINT OO 4 OO & FORMA ( SPEC FY BY NUMBER ( IN EGER) ) GO TO 22 S D R EO GO TO 7 & S2 PRINT OO 5 OO 5 FORMAT (A NPUT TIME STEP FOR I. RRAD I ATION V ) READ ( ERRE 62). DR IF (DT REO 0 ) GO TO 7 A PRINT 006 l OO6 FORMAT ( / COEFFICIENT MATRIX F OR 1 R RAD IATION ) 20 A PRINT OO 1 OO FORMAT ( / NPUT FILE NAME t ) READ (1 02 ER RE 208 ). FIE 1002 FORMAT (A8) CAL TRM UE ( , MA, E W FL. UX DAM D R F E LENGTH MAX) GO TO 64 S 3 PRINT 1 007 OD 7 FORMAT ( / R RAD IATION TRANSITION MATRIX ) PR l NT 1 001 READ (1 OO 2 ER RE 6 S) F I LE CALL IN MAT (T MAT EW FLUX DL AM D R FIL E LENGTH MAX) 6 A PR IN 1. OC 8 D IR 08 FORMAT ( / CH DOSE OPTION 2 5 OR & FOR NO FLUX OT I R = F 75) READ (1 ER RE 64 ) OP GO TO ( 64 72 75 74 ) OP P R N T 004 GO TO 64 72 CA 2: UTE (TMAT DEV 2 FLZ. R O DL AM DT J R N OF LUX & L. A X D) G C T 74 75 PR 'N 009 DT R 1 C (9 FOR MAT ( / NO F L UX DECA, Y MAT R X DTE F 7 5) - R J "T. l. C. Ol F. El O ( 2 ER RE 7. ) F E 4,721,596 27 28 CALL INMAT ( TM A TD EW Z FZERO OLAM OT REG F I LE ENGTH M A X D ) F (DT REGE GOT R ) GO TO 74 PRINT 1 Oil O O. O. FORMAT ( R ONG M. NERVAL ) GO TO 6 A 7 & PRINT Oll Ol FORMAT ( / CHOOSE OPTION 1 - A FOR NO-FLUX ST AND ING MATRIX ( ) READ ERR = 74 ) OP GO TO (8 82 83 84 ) OP PRINT 1 004 GO TO 7 A 8 DST GOTO 84 32 PRINT O2 Ol2 FORMAT ( / INPUT STANDING IME STEP) REAO ( a ERR ca. 2) OS F (OST ECO ) GOTO 84 CAL ZMUTE (TMATS EW ZF LZERO OAM DT ST NOFLUX 6 LM AXO ) GO TO 84 BS PRINT 1 013 Ols FORMAT ( / NOFLUX ST AND ING MATRX PRINT OO READ o O 2 ERR 83) FILE CALL IN AT (TMA. SEW Z FZERO OAM D S T FIS ENGTH LMA XD ) 34 PRINT 1 0 1 A 14 FORMAT ( / CHOOSE OPTION FOR CONCENTRATIONS ( A 2 NPUT M 2 LEAVE AS IS READ ( RR at 84) OP GOTO (91. 92) OP PRINT GO 4 GOO 84 9 PRN OOl READ (1 002 ERR 91) F LE CAL NAMT (AMT FILE ENGTH 2. 92 PRINT OS O 5 FORMAT ( / CHOOSE OPTION FOR DUMP e / 9 INPUT "f 2 2 LEAVE AS IS / S. SET TO 2 ERO V ) READ ( A ER RE92) OP GOTO (939 495) OP PRINT 1 (04 GO TO 92 95 OO 96 JEN ON HIGH 96. DU P J 0. GO TO 94 33 PRINT 0 Ol R. A.D. ( 1 OC 2 ER RE 93 ) F I LE CALL IN AMT ( OUMP FIL E LENGTH) 9 PRI'T O 6 1 D16 FORMAT ( / Cht OOSE OPT I O N 2 OR S FOR CH M C A L PROCESS ING ( ) REA) ( a ER RE 94 ) OP GO TO (1 C 1 O2 C5) IOP PR T 04 G) O 9 99 PR ' T 1051 K V (K) l 5 FOR '4 AT ( RR OR IN CHE CAL PP OCESS N G F 2 / V ( 5 ) F 6, 3 } GO TO 94. OS DO O. 4 JEN LOW Nhi Gh 04 W (J) = 0. GO TO O2 Ol PRINT O Ol READ (l OO 2 ERREl Ol) f l LE CALL IN A M T ( V FIL E LENGTH) OO 98 K = N - O NHI Ghi 9 8 IF ( V (K) LT . O. OR V (K) . GT 1 - 0 ) GOTO 99 O2 PRINT O 7 FoRMAT ( / CURRENTLY Ts F 1 O. 3/ INPUT THE WALUE YOU 2 ANT T TO HAVE ) READ ( ER REl G2) T AN EAT 4,721,596 29 30 97 PRINT 1 O30 AN O FOR MAY (A CURRENTLY NUMBER OF NEUTRONS USED = F 9.5/ 2 N P J T H E VALUE YOU WANT IT TO BE t ) READ (l ER RE97). AN 1 PRINT iO32 FISS 032 FORMAT ( / CURRENTLY AMOUNT FISSIONED = t , F 9.5/ 2 NPUT THE WALUE YOU ANT O BE ) READ (1 f ERRE FISS PRINT 1 Oil 8 1018 FORMAT ( / PDO YOU ANT CHEM CAL PROCESS NG BEFORE 2 FIRST R RADATION 2 . ) READ ( ) O 9) A NSW O 9 FORMAT (A1) IF (ANSWEG, PN ) GO TO 05 CAL PROCES (WAMT DUMP N ) 1 O 5 PRINT 1D 20 20 FORMAT (A INPUT NUMBER OF STEPS FREQUENCY OF OUTPUT ) READ (1 a RR: 1 (5) NT NTPR CALL RUNDAT (FLUX D, R, DTST NOWN HIGH ISO (NLO) ISO (NHI GH) 2 NT NT PRAN, FSS) CALL PRAM (AMT OUP DAM ATT ATWT FLUX) NAE 0 O) 2 J2 NT TT DT R CAL NEW CON (TMAD DUMP N LMA X D D, I R 0 ) CAL NE CON (fMA AMT V LMAX DTR FLUX) to DTST CALL NEW CON (TMATS DUMP N LMAXD DTST . O. ) CA NE CON (TMATS AMT N LMA X D DTST 0 . ) CAL PROCES ( V AMT DUMP N) NT AL ENT A 4 F NT. At , , , NTPR) GOTO 2 TAL E CALL PRAMT (AMT DUMP DL AM A TTI A TWT FLUX) 2 CONTINU PRINT 02 FORMAT ( / A NS R Y S OR NO TO THE FOLLC "... G. GUEST ON St M 2 SHOULD THE I R RAD I A T Of T R ANSIT I )N M A T R Y BE SA v D2 t ) PA O ( 9 ). A f Sl F (ANSE O N ) GO TO 6 CALL OUT M RT (T M AT E W DL AM DT R FLUX MAX) C 6 PR J N T 22 SUBROUTINE MAN l 022 FORMAT ( / 2. SHOULD THE DUMP TRANSIT ION MATRIX BE SAVED 2" READ (1 O 19) A NSW IF (ANSEG - N ) GO TO O7 CALL OUT MAT (TMAT DEV2 DAM DT I R FLZERO MAXD ) G 7 PRINT 1025 - 023 FORMAT ( / 3 SHOULD THE STAND ING T R ANSIT ON MATRIX BE SAWE D?") READ ( Ol 9 ). A NSW IF (A NSW. E.g. N t ) GO TO C8 CALL OUT MAT (TMAT SEVZ OAM DTST FLZER 0 LMA X D) 8 PRIN 1024 C24 FORMAT (A 4 SHOULD CONCENT R A ONS BE SAW ED2 " ) READ ( Oil 9) ANS IF (ANSE O N ) GO TO 109 CAL OUT A MT (AMT) 1 O 9 PRINT 1025 1 O25 FORMAT ( / 5 SHOULD OU MP BE SAVED2 ) READ ( ) 1 0 19) ANS IF ( ANS E G N ) GO TO O CALL OUAM (DUP) 1 O PRINT 26 1026 FORMAT ( / 6 DO Y O U W A NT TO CONUE 2 " ) READ (1 O 19) At SW F (ANS N E N ) GO TO 4,721,596 31 32 C All SRCHSS (KSC OS OUT 3, 4 I I C) PRINT 27 0.27 FOR AT (M TO SPOO RESULTS TYPE e A SPOOL OUT - FTN RETURN ENO
SUBROUTINE TRUTE (TA E V FLUX D A M T , F Elf El AX)
SUBROUTINE TRUE (TMAT EV FLUX D AM FIL. F. L. LA ( ) DIMENS ON AT ( 25 O & O ) EV (250 ) O AM (250) EEW (25 O) 2 DFS 25 O) Ot. ABS (25 O ) EI (25 O) C 9 - ON AIM S/NO NHI GH NSAD NBN. NBB B BNL BB COMMON/T OPES/A (25 O Z (25 O ) ISO (25 O N A OSS COMO NAAT SAFACT ONEU (25 0 ) . A N E U (25 O ) F SS (250 REAL 8 FILE ISO SOT ( ) S INSERT SYSCOM > KEYS. F S INSER SYS COMXERR D F 7 C. Lt. SRCHSS ( K S READ FILE FILE 2 T C) F ( C E G O ) GO TO 6 S PRINT GO A FE OA FORMAT ( UNABLE TO OPEN FILE A8 a 2 Me INPUT FILE NAME ) READ ( O O 6 ERR 8) FILE OO 6 FORMA. As GOO 7 s READ (6 OOO ) FLUX NBN E - NBB is a UNIT = 1 - FA C E A 4 OOO FORMAT 2E. A 7) FLUX 3 600 t FLUX XLOGE ALOG (2s CA. SRCHSS ( K S READ DA A A 1 I C ) DO NE 25 C. REAO (5 OO Z (N) El A N ) S. G. S GF Ol FORMA (SX S A 2 S S A F N NL O GO TO F (N. G. N. GH) GOTO 2 F C E E GOTO 2 EN CODE (8 OO2 SO ) IZ (N) I A N) OO2 FORMA ( S A 2 S ) SO(N) SOT ( ) F C E O GO TO O OAM (N) : X OG AT DLF S (N) at S GF F X / E 24 DLABS (N) = S I Grr LUX /l. E24 DNEUT (N) :) ABS (N) - FACT DLF I ( ) EV (N) E- DL AM (N) - O ASS N) + DL, S (N) F EW N E O S GOO EEW (N) : Z.EXP ( EV (N) t T ) I ( N) = - ( 1. - E W T (N) ) / w ( N ) CONT UE N EN + N - 8 PRINT 1 CO7 G O 7 F 3 RMAT ( i INPUT NBA D ) R E A D ( ER RE 8 ) AD L = ( ; , D ) DO S N A UT ( , ) O F SS ( , ) O. DO S l l 40 T - A T ( ) 4,721,596 33 34 LAX 20 A. READ ( 6 OOS) J K AMT IF (J EQ NBAD) GOTO 5 OO3 FORMAT ( 3 A El 5, 7) 6 IF (IE ( ) OR I GT NHIGH) GOTO 5 IF (I L T N LOV) GO TO A F ( J. G. N. Gh ) GO TO 4 L EJ - It LMAXE MAX (L MAX) XE AT YEEVT (K) /UNIT Y AM ET (Ky MNT MA ( L) MA ( ) 0-X ANEUT ( ) E A NEUT ( ) + ONEUT (J) Y FISS ( , ) cFI SS ( ) 4-DFS (J) e Y GOO 4 5 CALL SRCHSS (KSCLOS FILE FILE 2 ITIC) CALL SRCHSS (KSCLOS DATA 4 IT IC) DO 2 JNO NHI GH SUMEF ISS (J) r " DO S KEl MAX IF (TAT ( J K) LT ... O ) TMA (J. K.) EO SUMSU M4 TAT (JK) S CONTINUE XEl e SUM F (ABS (X) G 0 ) , ). PRINT 005 J X TMA (JAO) EXf A (J) 2 CONTINUE 005 FOR MA ( / WSUM TMAT ( 3 K) cla El O.S.) CALL THATP (TMAT EV DLAM T ) RETURN 0 OLAM (N) E 0. GO TO 4 EEWT (N) at ET (N) ET GO TO 5 F (2 (J) + A (J) - 2 ( , ) as A ( ) NE ) GOTO 6 IF (IZ (J) E G 2 ( , ) GOTO 7 NBBE BBC OAM ( ) GO TO 6 7 NB NE I B NED LABS ( . ) GOTO 6 ENO SUER OUT IN E ZMUTE (TMATE W FLUX OLAM T F L E L FILE, LMAX) DIMENS ON T MAT ( 25 O 4 0 ) EV (250) DLAM (250 ) , E W T ( 25 0) COMMON / I M I TS MNL. O. NH GH COMO NATO PES/ I A (25 O) Z (25 ) ISO (25 O A LOSS REAL 8 F 1 - E ISO El ISO ( , ) NS R T S YS COM > KEYS. F I NSER T S Y S COMXR R D F .7 CAL SR Chi S S K S READ F L E LF L E 2 I C ) F ( I C E O - C ) GO TO 6 S Pk I NT 1 OOA F L E LENGTH 4 F (k - A T ( ' UNABLE TO OPE FILE t A8 OF LENGTH 2, 1/ PUT F I LE t t . . . ; (, TH) R EAD ( ERR = 8). FIE LENGTH GO TO 7 s READ (6 OOO) FLUX UNIT F 1 - OOO FORMAT (2E 4, 7 ) FLUX S600 t FUX XL0. GE ALOG (2) CAUL SRCHSS (KS READ DATA 4 l IT I C) D0 NEl 25 O READ (5 901 ) I Z (N) El IA (N) TH SIG 1 OO FORMAT ( 3X 3 A2 5 2E lll . . ) F (NL NLO) GOTO IF (N - GT N H IGH) GOTO 2 IF ( E L E G ) GO TO 2 35 4,721,5 96 ENCODE (8 1 00 2 1 SOT ) 2 (N) El I A(N) 1 002 FORMAT ( I 3 A2 IS) IS) (N) E. SOT ( ) IF ( T H E O - ) GO TO O DLA(N) EXO GAT l EW (N) on OAM (N) + SIG h FLUX7 E24) EE W T (N) : Z.EXP ( EV (N) T ) CONTINUE N N + 1 2 NeNe DO 3 N OO S L at 40 S MAT ( L) = 0 LAXE A. READ (6 0 OS) J K . A CO3 FORMA ( 34 El 5, 7) IF (IEGO OR GT NH Gh) GOTO 5 F ( LT NO GO TO 4 F (JGT Nhi GH) GO TO 4 EJ - 0 MAX-MAX ( LMAX) TMAT ( , ) at TMAT ( I L) + AMT EEVT ( K ) / 'w T GO TO A 5 CAL SR CHSS (KS CLOS FILE - F - 2 T C) CALL SRCHSS (KSC OS D A A 4 C ) OO 2 JEN ... O J N H GH SUMO DO 1 S K E LAX F (TMA ( J K ) . L T O. ) TMAT J K ) Oo SUMESUM + M. A (J K ) 3 CONTINUE xt - SUM IF (ABS (X) GT. C. Ol) PRINT 005 J X TAT ( J 4 C ) = x t I A (J) 2 CONT NUE C 5 FORMAT ( / SUM T A T ( 3 K ) = 1 - E O S CALL TMA. T P ( , MA. T E W LA M T ) RETURN 0 CLA, (N) : 0. GO TO WD SUBROUTINE NE CON (TMAT CONN N MAX DT F-UX)
SUBROUTINE NEW CON (TMAT CON NNL. MA X DT FLUX) DIMENSION TMAT ( 250, 40) CON (250) TCON (250) REAL t 8 ISO COMMON / I MIT SAN LOV NHI GH NBAD NBN NBB BL BNL BB COMMON / TO PESA A (25 O ) Z (250 ) , I SO (25 O ) N ALOSS COMWON / AMTS / FACT ON (25 O ) A N (25G) F (25 O ) CD M M ON / TOTS/AMTN AMTF I F (DT ECO RETURN DO JFNO NH IGH TCON (J) CO DO LE 1 LMAX IEJ - 4 IF (I LT N LOV) GO TO T CON (J) ET CON (J) --T MAT ( I L ) t CON ( ) CCNTINUE OO 2 IN LOW NH Gh A LOSS E ALOSS + T MAT ( I AO) a CON ( ) IF (FLUX Q O ) GO TO 2 AN EATN 4-AN ( ) CON ( ) AMT FEAM F + F I ( ) a CON ( . ) 2 CON ( . ). ET CON ( ) R E U R N END 4,721,596 37 38 SUBROUTINE PRAMT (AMT DUP DAM ATV A TV FLUX)
SUBROUTINE PRAMT ( AMT DUMP DL AM AT W T A TWT TFLUX) DMENSION AT (250) DUMP (250 ) , DL AM (25 O) REAL 8 SO COM 3 N / Ll MITS/NLOV NHIGH NBAD NBN NBB BL BNL BBL COMON / TOPES/ I A (250) I2 (250) ISO (250) NALOSS COMO NATO SAAN AF COMMON/A MTS / FACT ONU (250) ANU (250) AFS (25 O) CALL ACT (AMT DUMP DL AM ACT I V N ) D3 EBL AMT (NBAO) IF (NBN GT O ) OBE DB+BN AT (NBN ) F (BB GT 0 ) OBE DB4 BBL AMT (NBB) ONE O DO 2 JEN LOW NHIGH 2 DNED N +ONU (J) AM (J) DNDB 9999999 IF (DB N E O - ). DND BEDNADB RITE (8 10 OO) FLUX ACT W AN OOO FORMAT ( 1 AMOUNTS AT T E F8 1 HOURS FLUX = El OS 2 ACT I W IT YE El O. 3 NEUTRONS USED E El 25 ' ' ) R. E. (8 O3) NO BAF OOS FORMAT ( O NEU/D BAO = El 25 FI SS ONS = El 25) N. N. NH Ghta-N LO 4 NL c (NN 0 1 1. ) M2 DO 1 JLF1. NL JM IN E J t 12 - 21 NLOW JAX EJL 12-14-NOW F J. E.G. N. L. JMAXEN Gh R T E (8 1 OO) ( ISO (J) J E J M N JMAX) RTE ( 8 O2) (AMT ( ) JEJM IN JAX) RTE (8 0 O2) (DUMP ( ) JEJM IN JAX) 1 OO FOR MA ( / 2 (X A8 X) ) OO2 FOR AT ( 12 E O S ) CONT ENUE RETURN ENO SUBROUTINE RUNDAT (FLUX DTI R DTST NL NH A B T N T N P ANF)
SUBROUT IN, RUNDAT (FLUX DTI R DTST N - N H A BT N T N P ANF ) REAL 8 AB S INSERT SYSCOMX KEYS. F INSERT SYS COMXERRDF CALL SR CHSS ( K S R D R RUN 2 T I C) READ (6 1 OOO) NUM 1 000 FORMAT ( I. 6) NUM NUM + RE INO 6 R T E (6 1 OOO) NUM CAL SR CHSS (KSC OS RUN A 2 C) T EVOE f-0 (DTI R v TS ) r MT PRINT = NP a (DTI R4D TST ) OO l Jel 2 WRITE ( 8 1 O Ol) NUM FLUX DTI R, DTST NL, A, NH, B, TT END AN, F, TPR INT RETURN 1 O Ol. FORMAT ( R UN NUMBER 14 X 6 / FLUX 6 X El C. 4 / IRR AD I AT I O N T I ME" 2 A X Ei O AM REST TIME X E. O. A / ISO TOP E R A N GE 7 X I 3 2X A8 3 O I 3 2X A8/ 4 / START ING T ME 7 X, El O. A / END ING T ME t 9 x El O. A M 5 START ING NEUTRONS E. O. 4 / START ING FISSIONS E O - 4 6. A PRINT TIME INTERVAL 1 0. A ) END 4,721,596 39 40 SUS ROUTINE NMAT (T MAT E W FLUX DAM OT FILE ENGTH LMAX)
SUBROUT 1 NE IN MAT (T MAT E V FLUX DLA M, DT , F 1 - E - ENGTH MAX) DIMENS ON T M AT ( 25 Os 4 0 ) , EV (25 ( ) DAM (25 O) REAL 8 SO FILE COMON / Ll I TS / NOW NIGHNl N2 NS Bll B2 BS COMMON/T OPES/ I A (250) Z (250 ) , ISO (25 D) NAOSS COMMON / AMTS / FACT DN (25 O ) AN (250 ) , F (25 O) S INSERT SYS COM > KEYS. F S INSERT SYSCO MERR D F 7 CALL SRCHSS (KS READ FILE LENGTH 2 C) I F ( C E O C ) GOTO 6 8 PRINT 100 4 FILE 1 004 FORMAT ( ' UNABLE TO OPEN FILE D A8 a 2 / INPUT FILE NAME t ) READ ( OO 5 ER RE8) FILE 1 OO 5 FORMAT (A8) GO TO 7 s READ (6 l OOO) NL NHLM A X DT FLUX FACT READ (6 000) N N2 N3 Bll B 293 OD O FORMAT ( 3 I & 3E2.0. 7) IF (NLO LTNL OR - NHI GHG T NH) GO TO 99 OO 1 JEN NH READ (6 1 00 l) JJ ISO (J) IZ (J) A (J) EV (J) OAM (J) TMA T & J 4 ( ) 2 ON (J) A N (V) F I (J) (TMAT ( J K K1 MAX ) OO FORMA 3 A8 2 4 3 2 O 7/3E2.7/8 (5E20 7/ ) CAL SRCHSS (KSCLOS FILE LENGTH 2 IT C) RETURN 99 PRINT OO2 O2 FoRMAT M FATA ERROR FILE DOES NOT CONTAIN NO C N & NH Gr. ) STOP END SUBROUT IN E OU MAT ( , MAT EVOLAM D FLUX MAX ) OMENSION T MAT ( 250 4 0 ) EV (250 ) , DL AM (25C) REAL tr8 SO FILE COMMON / I MITS/NO Nh Gh N N2 N3 B B 2 B3 COMMON / TO PES/A (250 ) 2 ( 25 0 ) ISO (25 O ) N A LOSS COMMON/ATS/FACT DN (25 O ) A N (25 g ) F I ( 25 0 ) S INSERT SYS COMXKEYS. F S INSERT SYS COMXER R D F EW GE 8 PRINT CO 1 OOO FORMAT ( INPUT FILE NAME ( ) READ ( 1 10 O5 ER RE 1 ) FILE 7 CAL L S R CHS 3 (KSRIT FIL E L ENGTH 2 T C) F ( I. C. EG - 0 ) GO TO 6 s PR J N f l OO 4 F LE 004 FORMAT ( ' UNABLE TO OPEN FILE A8 2 / NPU F E N A M . . ) READ ( ) l OO 5 ERR = 8) F I LE O C 5 FORMAT (A8) GO TO 7 s F | T E ( 6 3 l ) " LO th G H ...... T , F - U x FA C a R. l T ( 6 C C ) N l N2 N 5 E b 2 5 0 U 1 FORMAT ( 4 3E2 G. 7) MXF MAX M5 X F = 5 v LMXF - MAX D0 2 JE - O NH I Gh 41 4,721,596 42 WRITE ( 6 10 O2) J 9 ISO (J) I Z (V) g IA (J) Ew (J) 2 DLA M ( J) TMAT ( J 40 y D. (V) y AN ( ) F I ( ) (TMAT (JK) K = MAX) 002 FORMAT ( 3 A8 2IA 320 7/5E2 O. 7/8 (5E20 7/ ) ) IF (MXF E G 0 ) . R. If E ( 6 OGS) OO3 FORMAT ( ' ' ) 2 CONTINUE CALL SRCHSS (KSC OS F 1 - E - ENGTH 2 IT I C ) RETURN ENO SUBROUT NE IN AM (AMT FILE LENGTH) DIMENSION A MT (25 O) REAL te 8 SO FILE COMON AL E M I TS M N () Nil GH N N2 NSB B2 B3 COMMON/T OPES/ A (250 ) Z (250 ) , ISO (25 O ) NALOSS S INSER SYS COMXKEYSF S INSERT SYSCOMXERRDF 7 CA. SR CHSS (KS READ FILE LEN G T is 2 C) IF ( C E G O ) GOTO 6 B PRINT 1 004 FILE OO 4 FORMAT ( UNABLE TO OPEN FILE t t t , A8. t 2 MV INPUT FILE NAME ) REAO (1 1 003 ER RE.8 FILE 1 O OS FORMAT (A8) GO TO 7 6 READ (6 000) NL NH OOO FORMAT (2 4 ) IF (NOT NL OR NIGH G T Nht) GOTO 99 DO 1 JEN NH READ (6 3 ) JJ ISO (J) AM J) OO FORMA ( 3 A8 E20 ) CALL SR Chi SS (KSCLOS FIL E L ENGT ri y 2 C ) RETURN 99 PR NT 1 CO2 O O2 FORMAT (A V FATA ERROR FILE DOES NOT CONTAIN NO C N C N H 1 GH ) STOP END sus RouTINE OUT AMT (AMT) O MENS ON AM (25 O) REA e 8 ISO FILE COMON / I MITS/N 0 NH GH N N2 NS Bll B2 BS COMMON / T OPES/A (250 ) . I 2 ( 250 ) ISO (250 ) , NAL OSS S INSERT SYSCOMXKEYS. F S INSERT SYSCOMXER R D F PRN COO COO FORMAT ( INPUT FILE NAME ( ) 7 READ 1 00 S ER RE ) FIL 003 FDR AT (A8) LENGTHE 8 CALL SR CHSS ( K R T FIL E L ENGTH 2 T 1 C ) I F ( CEO. . ) GOTO 6 8 PR IT 4 F 1 : C 4 F O 2'. A T ( t UNABLE TO OPEN F I LE t t t A8 2 A t PUT FILE NAME ( ) G O O 6 R T E ( 6 Cl) L. O. H. GH 0 U 1 F OR ' A T (2 4 ) DO 2 JNLO a NHI GH 2 RITE (6 1 OO2) J SO (J) AMT (J) l OO 2 FORMAT ( I 5 A8 E 2 O. 7) C All SRC SS ( KS CLOS FILE LENGTH, 2 IT Ic) RETURN END SUBROUTINE T M ATP (TM AT, Ev, Dl AM, DT ) DIENSION TMAT ( 25 O & O ) V (25 O), OAM (25 C00 N/T OPES/ I A (250 ) , I 2 (250 ) , ISO (250 ) , N, ALOSS REAL 8 ISO COMON / I MIT S / NLO NHI GH N1, N2, N3 B, B2, B3 COON / AMTS / FACT DNEUT ( 250 ) . A NE UT (25 D F I SS (250 RITE (8 G CO.) DT DO JFNLO N H IGH ZET MAT ( J 4 O ) 43 4,721,596 44 WRITE ( 8 O Ol) J SO (J) EW (J) D-AM (J) 2 DNEUT ( J) 2 A NEUT (J) F I SS (J) (TMAT ( J K ) KF l 40) RETURN OOO FORMAT ( // TRANS IT ION MATRIX FOR OT = El 4.3 "HOURS ) OO FORMA ( / SPECIES a I 3 SX A 8 EV El 4 5 DLA M 2 El 4 5 LOSS El 4.5 / DN EU El 4 - 5 3. ANE UT E 145 FISS El 4, 5 4 ( / ) X 12 El 0 - 5) ) EN) O A19 ( ) SUBROUTINE PROCES (WA O N )
SUBROUTINE PROCES (W A O N ) O MENS ON W. ( 25 0 ) A (250) D (25 O) COMMON / I MITS / NOW y NHI Ghi N N 2 v N Bll 82 BS DO JEN LOW N H IGH XV c. J. A ( ) D (J) ED (J) t X A (J) E A (J) - X R E U R N END SUBROUT IN E A CT ( A D DEC A Y At N) DIMENS ON A (250 ) D (250 ) DECA Y (25 O ) COMMON / I SMNLO NH GHN N2 N 3 81 B2 B3 AMT O. DO NO NH Gh A T AMT t (A ( ) + O. J.) ) to ECA Y (J. RETURN END FUNCT ON MAX ( I J) MAX at I F (J. GT ) MAX EJ RETURN ENO FUNCT ON 2 EXP ( x ) ZEXP. O. F ( X GT ar. O. O. ) 2 EXPE EXP (X 9 RETURN END SUBROUT IN E IN DATA
SUER OUT INE ENDA A REAL 8 FILE S INSERT SYSCOMXKEYS. F is I NSERT SYSCOMXERRD F 9 PRINT O 0 FORMAT ( / F 1 NPUT FILE NAME ( ) READ ( G O O ER RE 9 ) FILE LEWG THE 8 OOO FORMA (A8) PRINT 12 12 FORMAT ( / V N T E R N LO NHIGH TO BE CHANG D REA O ( ) ERRE ) NO NHIGH PRINT FORMAT ( / O FOR EACH ISOT OPE ENTER HAF I FE 2 CROSS SECTION AND F I SS I O N CROSS SEC T ON . ) CALL SR CHSS ( K S READ DATA A 1 T I C ) CALL SR CHSS ( K S R T FILE N G T H 2 I C ) CODE: O NNE READ (5 y 6) N B A C X Y 2 NNENN + 1 F (AEG ' ' ) GO TO 7 IF (NLT NL OF OR - N - GT - NHIGH) GO TO 3 45 4,721,596 46 PRINT 6 N N B A C READ (1 ER RE 4) X YZ RITE ( 6 6 ) NN B A C X Yg Z FORMAT (23 A2 3 31 . . ) GO TO 2 7 BEG A CEO RITE (6 6 ) B B A C C C PRINT B FILE 8 FORMAT ( STORED IN FILE t t A8 ) CALL SRCHSS (KSC OS D A A 4 T I C ) CALL SRCHSS ( KS CLOS FILE LENGTH 2 IT C) RETURN END SUSR OUT NE 1 NCA
SUBROUTINE NCHA Dl ENS ON ANAME (250) BN AME (250) K K (250) S NSERT SYSCOMXKEYS. F SINSERT SYSCOMXERRDF CALL SR CHSS (KS READ DATA 4 IT C) CAL SRCHSS (KSWRIT CHA INS 6 2 T C) DO 1 JF 250 READ (5 l00 2 J J A NAME (J) BN AME (J) IF ( J J E G O ) GO TO 2 4. PRINT 1 Ol J JJ ANAME (J) BN AME (J) Ol FORMAT (2I4 2A A) READ (1 t ERR- A ) KK (J) 2 DO 3 JJ El J KKJKK ( JJ) 5 WRITE ( 6, 1 O2). ANAME (JJ) BNAME (JJ) A NAME ( KKJ) BNAME ( KKJ) CALL SRCHSS (KSCLOS DATA 4 IT C) CALL SR CHSS (KSCLOS CHA INS 6 2 IT C) RETURN 00 FORMAT (I 32A 4 ) O2 FORMAT ( FROM 2A 4 TO 2A4 ) END SUS ROUT NE IN CASE SUBROUT NE IN CASE REAL 8 FILE S INSERT SYS COMXKEYSF S INSERT SYS COMXERR OF 9 PRIN 1.0 1 O FORMAT ( / INPUT FILE NAME ( ) READ ( 1 4321 ER RE9). FILE A 32 FOR MA (A8) LENGTH 8 P R N T 2 l2 FORMAT ( / ENER NOW NH 1 GH ) REA O ( - ER REll) NO NH GH PRIN, FORMAT ( / FOR EACH ISOT OPE ENER INITIAL CONCENTRATION 2 OR FRACTION DUMPED ) CALL S RCHSS ( K S READ 'DA TA" A l I I C) CALL SR CHSS (KSRIT F 1 - E LENGTH 2 T C) R. If E ( 6 15) NO NHIGH 13 FORMAT (21. A ) IF (NLO EQ l) GOTO 2 NMEN LOV O O. A JEl NL 1 A REAO (5 15) JJ 15 FORMA ( IS ) 2 READ ( 5 S) N B v. A C 5 FORMAT ( 2 I 3 A 2 S ) IF ( A. E. G. ) GO TO 7 PR N S N B A C 4,721,596 47 a 48 READ (1 ER RE 4) X RITE (6 6) N.B A C X 6 FORMAT (21 S A2 I 3 E20 - 7) IF (NL NH GH) GOTO 2 7 BO At CO WRITE (6 6 ) 8 By A y Cy C PRINT 8 FILE t B FORMAT (VSTORED IN FILE A8 ) CALL SR CHS 3 (KSCLOS D A A' 4 l IC) CAL SR CHSS (KSC OS FILE LENGTH 2 IT 1 C ) RETURN END SUBROUTINE NUCL SUS ROUTINE NU C DIMENSION I TAB ( 50 50) JT AB (6 8 2 ( ) JZ (6 82O) N M ( 6 8 20) DIMENSION I Z (225) IEL (225) A (225) HL (225) CCS (225) Yi E. D (225) DIMENSION IS (225) A YIE ( 6 8 20) JBUF (l2O) JD (5) J S (6 8 20) DIMENS ON JEL ( 6 8 20) JA ( 6 v 8 20) AH (6 8 20 ) . A CCS (6 8 20) O I MENSION LINE (20) INTEGER 2 D (8) S INSERT S Y S COMXKEYS. F S INSERT SYS COMXER R D F CALL SR CHSS ( K S READ D A A 4 2 C) CAL SR CHSS ( K S READ V IN CON 5 4 C ) CALL SRCHSS (KS READ FOU 4 5 T C) CAL SR Chi SS (KSRI D OUT 4 S IT I C) El Ol READ (6 20 OX NUMB Z ( ) IE ( ) A I hl ( I CCS 200 FORMAT ( 2 S A2 I S. 2E lll . A ) F ( NUMB EQ. O J GO TO 00 E + 1 GO 0 1 0. OO St E I as DO O2 Eli tST READ (8 20 l) YELD ( ) S ( . ) 2 Ol FORMAT ( X E20 7 A O2 CONTINUE DD 1 0 1 50 DO Je 150 TAB ( I J } E 0 l CONT NUE O CONTINUE KKEZ ( , ) is LLE A (1) rl AB ( ) El OO 4 O E2 S. : . 2 (M) - KK J: A (M) - 4 AB ( J) cM Kc IST El JS El DO 20 6 DO 21 Jl 8 77 - I JT AB ( 7 J ) I AB ( J) 2 CO W T NUE 20 C O N T NUE 26 COUNT El JST J S + 7 2 3 I F ( ). T AB ( ST JST ) N E O ) GO TO 22 COUNT COUNT + 1 F ( I COUNT E G 6 GO T ) 27 S T t I S T GO TO 25
4,721,596 SS 56 CALL SRCHSS (KSCLOS 0, C , 2, IT I C) CALL SR CHS 3 (KS CLOS 0 0 S IT C) C All SRCHSS (KS CLOS C 4 IT C) CALL SR CHSS ( KS CLOS O 5 IT C) RETURN END
What is claimed is: 1. A method of decreasing the amount of relatively 10 lected in accordance with said long lived fission long lived fission products in radioactive waste materi product nuclide contained therein for inducing als in excess of that due to their natural radioactive predetermined transformations of said long lived decay by producing relatively short lived radioactive nuclide to further produce relatively short lived nuclides and stable nuclides from said relatively long radioactive nuclides and stable nuclides; lived fission products comprising the steps of: 15 (j) removing said at least one other further group (a) separating said fission products into at least (1) a containing said further produced relatively short plurality of physically separate groups, each of said lived radioactive nuclides and stable nuclides from groups having at least one relatively long lived said high thermal flux; fission product nuclide selected from the group (k) separating said removed other further group into comprising Se79, Kr85, Sr90, Zr'93, Tc99, Pd 107, (1) said further produced short lived radioactive Sb.125, Sn 126, 129, Cs135, Cs137, Pm 147, Smi51--Eu, nuclides and stable nuclides, and (2) yet another and actinides, and (2) relatively short lived fission group containing said long lived fission product product radioactive nuclides and stable nuclides; nuclides of step (i); (b) storing said relatively short lived radioactive nu (1) storing said further produced short lived radioac clides and stable nuclides; tive nuclides and stable nuclides; and (c) exposing at least the groups containing Kri, Sr', (m) storing said long lived radioactive nuclides of Zr93, Tc99, Pd 107, I 129, Cs135, SmlS1--Eu, and acti steps (e) and (k) after they have reached a reduced nides, to a high thermal neutron flux for separate, level of radioactivity over their natural decay. different predetermined periods of time selected in 2. A method as recited in claim 1, wherein a compo accordance with the long lived fission product 30 nent comprises Se79. nuclide in said corresponding group for inducing 3. A method as recited in claim 1, wherein a compo predetermined transformations of said relatively ment comprises Krypton. long lived fission product nuclides to produce rela 4. A method as recited in claim 1, wherein a compo tively short lived radioactive nuclides and stable nent comprises Strontium. nuclides; 35 5. A method as recited in claim 1, wherein a compo (d) removing each exposed group containing said nent comprises Zr'. produced relatively short lived radioactive nu 6. A method as recited in claim 1, wherein a compo" clides and stable nuclides from said high thermal nent comprises Tc'. neutron flux; 7. A method as recited in claim 1, wherein a compo (e) separating said removed group into (1) said pro ment comprises Pd(07. duced short lived radioactive nuclides and stable 8. A method as recited in claim 1, wherein a compo nuclides, and (2) a plurality of further groups hav nent comprises Sn2. ing long lived fission product nuclides respectively 9. A method as recited in claim 1, wherein a compo corresponding to at least some of the long lived nent comprises Sb.125. fission product nuclides or said plurality of groups 45 10. A method as recited in claim 1, wherein a compo of step (a); nent comprises Iodine. (f) storing said produced short lived radioactive nu 11. A method as recited in claim 1, wherein a compo clides and stable nuclides; nent comprises Cs. (g) joining at least one of said plurality of further 12. A method as recited in claim 1, wherein a compo groups to at least one of said plurality of groups of 50 nent comprises Cs17. Step (a) having a corresponding long lived fission 13. A method as recited in claim 1, wherein a compo" product nuclide; nent comprises Pm 147. (h) repeating steps (c)-(f) at least one time; 14. A method as recited in claim 1, wherein a compo (i) for at least one other further group, maintaining 55 nent comprises Sms, same separate from said plurality of groups of step 15. A method as recited in claim 1, wherein a compo (a) while re-exposing same to a high thermal neu nent comprises Europium. tron flux for a predetermined period of time se sk k sk sk ck
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