PFC/RR-91-9 DOE/ET-51013-292 A COMPARISON of RADIOACTIVE WASTE from FIRST GENERATION FUSION REACTORS and FAST FISSION REACTORS with ACTINIDE RECYCLING* M. Koch and M.S. Kazimi April 1991 Plasma Fusion Center and Department of Nuclear Engineering Massachusetts Institute of Technology Cambridge, MA 02139 U.S.A. *This work was partially supported by EG&G Idaho, Inc. and the U.S. Department of Energy under DOE Contract No. DE-AC02-78ET-51013 and DE-FG02-91ER-54110 Reproduction, translation,publication, use and disposal in whole or in part, by or for the United States government is permitted A Comparison of Radioactive Waste from First Generation Fusion Reactors and Fast Fission Reactors with Actinide Recycling by M. Koch and M.S Kazimi Abstract Limitations of the fission fuel resources will presumably mandate the replace- ment of thermal fission reactors by fast fission reactors that operate on a self- sufficient closed fuel cycle. This replacement might take place within the next one hundred years, so the direct competitors of fusion reactors will be fission reactors of the latter rather than the former type. Also, fast fission reactors, in contrast to thermal fission reactors, have the potential for transmuting long- lived actinides into short-lived fission products. The associated reduction of the long-term activation of radioactive waste due to actinides makes the comparison of radioactive waste from fast fission reactors to that from fusion reactors more rewarding than the comparison of radioactive waste from thermal fission reactors to that from fusion reactors. Radioactive waste from an experimental and a commercial fast fission reactor and an experimental and a commercial fusion reactor has been characterized. The fast fission reactors chosen for this study were the Experimental Breeder Reactor II.(EBR-I1) and the Integral Fast Reactor (IFR). The fusion reactors chosen for this study were the International Thermonuclear Experimental Reactor (ITER) and a Reduced Activation Ferrite Helium Tokamak (RAFH2T). The four reactors considered operate on an idealized self-sufficient closed fuel cycle, i.e. actinides and tritium are regarded as fuel and recycled back to the reactor. In the case of the two fast fission reactors, actinide recycling is possible without detrimental effects to the neutronics, because at the very high average neutron energies in these reactors, not only plutonium, but also most other actinides become fissionable, i.e. constitute fuel rather than poison. Realistically, the radioactive waste from the two fast fission reactors will contain some actinides and that from the two fusion reactors will contain some tritium. However, since actual separation efficiencies are expected to be in the 99.9 % range, the radioactive waste will contain less than 0.1% of the actinides or the tritium. In contrast, thermal fission reactors do not operate on a self-sufficient dosed fuel cycle and hence their radioactive waste contains up to 100% of the actinides. The fast fission and the fusion reactors have been approximated as a set of homogenized reactor components of simple cylindrical and/or hexagonal geom- etry. Reactor components as radioactive waste were characterized by several 2 parameters. These parameters describe the volume and activation of radioactive waste and are pertinent to US regulatory standards. Build-up and decay of radionuclides in reactor components were simulated by the computer codes ORIGEN-I for fast fission reactors and ONEDANT and REA C-IMfor fusion reactors. Auxiliary computer codes were developed to convert the output of those three computer codes into radioactive waste parameters. The parameters were not normalized to the different power levels of the compared reactors, but rather evaluated for these reactors as built. The comparison of radioactive waste parameters shows that radioactive waste from the experimental fast fission reactor may be less hazardous than that from the experimental fusion reactor. Inclusion of the actinides would reverse this conclusion only in the long-term. Radioactive waste from the commercial fusion reactor may always be less hazardous than that from the commercial fast fission reactor, irrespective of the inclusion or exclusion of the actinides. The fusion waste would even be far less hazardous, if advanced structural materials, like silicon carbide or vanadium alloy, were employed. Also, radioactive waste from the experimental fast fission reactor may be less hazardous than that from the commercial fast fission reactor. This is a direct consequence of the utilization of highly 235 U enriched fuel in EBR-IH resulting in a lower activation than the utilization of uranium-plutonium-minor-actinides fuel in IFR. Radioactive waste from the commercial fusion reactor may be less hazardous than that from the experimental fusion reactor. This is a direct con- sequence of the utilization of standard materials (SS316) in ITER resulting in a higher activation than the utilization of Reduced Activation Materials (RAF) in RAFHT. The generation of High Level Radioactive Waste (HLRW) is likely not to be avoided even for RAPHT. The volume of radioactive waste from the two fusion reactors is larger than the volume of radioactive waste from the two fast fission reactors. Material selection in the fusion reactors plays a far more important role in controlling the activation of the radioactive waste than it does in the fast fission reactors. If recycling of fusion reactor structural materials is found feasible in the future, the volume of radioactive waste from fusion reactors will be reduced. 3 Acknowledgements This report is based on the thesis submitted by the first author to the MIT Department of Nuclear Engineering in partial fulfillment of the re- quirements for the degree of Master of Science in Nuclear Engineering. Our gratitude is directed to Robert Hill from the Argonne National Lab- oratory and Yousry Gohar from the Argonne National Laboratory,who kept us up to date on the IntegralFast Reactor and the International Thermonu- clear Experimental Reactor, respectively. Bhavya Lal from the Massachusetts Institute of Technology and Fred Mann from the Hanford Engineering Development Laboratorywere of valu- able help in the proper application of the ORIGEN-I and REA C-Il codes. Our special gratitude goes to John Massidda from Grumman Space Sys- tems, who provided literally invaluable help in all aspects of the application of computer codes. The same holds true for Robert Thayer and Mark Lon- don from the MIT Plasma Fusion Center. The comments provided by Stephen Herring and Steven Piet of EG&G Idaho, Inc. on a draft of this report are greatly appreciated. Elizabeth Parmelee from the MIT Department of Nuclear Engineering and Janet Anderson from the MIT Plasma Fusion Center contributed great administrative support. We gratefully acknowledge partial funding for this report provided by the Office of Magnetic Fusion Energy of the U.S. Department of Energy. 4 Contents 1 Introduction 15 1.1 Topic & Motivation .. .. .. .. .. 15 1.2 Background . .. .. .. .. .. .. - . 17 1.3 Focus .. .. .. .. .. .. .. .. -- 19 1.4 Structure . .. .. .. .. .. .. 23 1.5 Previous Studies .. .. .. .. .. 24 2 Radioactive Waste Parameters 26 2.1 Introduction .......... .. .. .. .. .. 26 2.2 Volume ................ .. .. .. .. .. .. 30 2.3 Radioactivity , . .. .. .. .. .. .. .. .. .. .. 31 2.4 Whole Body y-Dose Rate . .. .. .. .. .. .. 32 2.5 Decay power . .. .. .. .. .. .. 35 2.6 Biological Hazard Potential .. .. .. .. .. .. 36 43I .7 Radioactive Waste C3lassircation ................ 2.7.1 Low, Intermediate and High Level Radioactive Waste 43 2.7.2 Class A, Class B, Class C and Class D Radioactive W aste . .. .. .. .. .. .. .. 45 2.8 Intruder Dose Rate .. .. .. .. .. .. 48 2.8.1 Construetion Scenario . .. .. .. .. .. 52 2.8.2 Agriculture Scenario .. .. .. .. .. 56 3 Methods of the Study 60 3.1 Introduction . .. .. .. .. .. .. .. .. 60 3.2 Fast Fission Reactors . .. .. .. .. .. 61 3.2.1 ORIGEN-II Neutron Activation Code .. .. 61 5 3.3 Fusion Reactors . ....... ...... ..... 62 3.3.1 VMIBOB Code ............... 62 3.3.2 ONEDANT Neutron Transportation Code 65 3.3.3 FLXWRT Code ............... 67 3.3.4 AVEFLUX Code .............. 67 3.3.5 COMCOMP Code ............. 69 3.3.6 REAC-II Neutron Activation Code .... 75 3.4 OPOPOST & RECPOST Codes .......... 76 3.5 Integration of the Codes .............. 78 3.5.1 Fast Fission Reactors ............... 78 3.5.2 Fusion Reactors ............... 79 4 Description of the Reactors 81 4.1 Introduction ........................... 81 4.2 Fast Fission Reactors ........... ........... 82 4.2.1 The Experimental Breeder Reactor II ....... .. 83 4.2.1.1 History & Objectives .. ...... ..... 83 4.2.1.2 Operation Schedule .............. 86 4.2.1.3 Design ..................... 88 4.2.2 The Integral Fast Reactor ........ ....... 92 4.2.2.1 History & Objectives ............. 92 4.2.2.2 Operation Schedule .......... .... 93 4.2.2.3 Design .......... ........... 93 4.3 Fusion Reactors .............. ........... 94 4.3.1 The International Thermonuclear Experimental Re- actor ........................... 97 4.3.1.1 History & Objectives ............. 97 4.3.1.2 Operation Schedule .............. 98 4.3.1.3 Design ..................... 100 4.3.2 The Reduced Activation Ferrite Helium Tokamak .. 104 4.3.2.1 History & Objectives . .... .... .. 104 4.3.2.2 Operation Schedule ... .... .... 104 4.3.2.3 Design .... .... ... .... .... 105 4.4 Radioactive Waste Processing for Fast Fission Reactors . 105 6 4.4.1