Reduction of nuclear waste toxicity by actinide recycling in fast and thermal reactors

After a storage time of 300 years, the activity of the fission products contained in nuclear waste is rapidly decreasing while the activity due to the long-lived alpha-emitters remains relatively high. A way to reduce this alpha activity consists of recycling the plutonium and the minor actinides (Np, Am, Cm; abridged in M.A.) in reactors, either with thermal neutrons (like the LWRs) or with fast neutrons (LMFRs). These two possibilities have been explored. The option of LMFR recycling means that, starting from the initial irradiation of UO2 in a LWR, Pu and M.A. are reprocessed and recycled several times successively in a LMFR. One has considered explicitly such a multiple recycling over a period of nearly one century. The option of LWR recycling means that after the initial LWR irradiation, Pu and M.A. are reprocessed and recycled first in a MOX-fuelled LWR, and then in LMFR as above. This presentation displays the following aspects: - the actinide production in PWR; - the actinide multirecycling in fast reactors; - the impact of recycling on fuel refabrication; - the actinide recycling in PWR (first results only). (authors). 2 tabs., 2 figs., 4 refs