Fast Reactors and Accelerator Driven Systems Knowledge Base

Conference Article: Characteristics of TRU transmutation in an LMFBR

Abstract

Feasibility studies of TRU transmutation in an LMFBR has been performed to establish TRU (exactly minor actinides) transmutation technology by in an LMFBR. Systematic parameter survey calculations were performed for a conventional 1000MWe LMFBR core to investigate basic characteristics of TRU transmutation in an LMFBR core and also to establish TRU loading method which has no serious influence on core design. TRU loading resulted in a decrease of the burnup reactivity loss, which is a desirable feature for the extension of reactor operation period. TRU transmutation rate reaches approximately 11% per cycle and the amount of the TRU transmutation with TRU ratio of 5% is almost six times as much as that of the TRU from a 1000MWe-class LWR. Homogeneous TRU-loading has almost no serious influence on core performances. However, it is desirable to limit the TRU loading ratio to several percent from the aspect of reactor operational safety. Heterogeneous TRU-loading method resulted in a larger power swing. Further optimization is necessary to clarify the feasibility of the method. Study on an innovative core concept for TRU transmutation was also carried out taking into account the results of systematic parameter survey calculations. Neutronic feasibility was studied on a 1000MWe Super Long-Life Core (SLLC) with no need of fuel exchange during plant life. The SLLC is an attractive option for transmuting TRU nuclides since it can transmute them with confining them into the reactor during plant life. It was found that remarkable reduction of both reactivity change and power variation during burnup is possible by optimizing the amount and zoning of TRU loaded. The reactivity change and the power swing during 30 years of the optimized core are less than half of those of the SLLC with no TRU loaded. The amount of TRU transmuted is about 10ton which corresponds to the amount of TRU produced by 13 LWRs. The SLLC loaded with TRU fuel was found feasible from the neutronic point of view. R and D programs are being pursued in PNC-Japan to establish the transmutation technology of TRU nuclides in LMFBRs.

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Reference:

Use of fast reactors for actinide transmutation. Proceedings of a specialists meeting, Obninsk, Russian Federation, 22-24 September 1992. Mar 1993.

International Atomic Energy Agency, Vienna (Austria)

IAEA-TECDOC--693, pp:99-108