The Effect of Swelling and Creep on Liquid-Metal Fast Breeder Reactor Performance

The impact of swelling and creep phenomena, as expressed in the various Nuclear Systems Materials Handbook correlations and their updates, on liquid-metal fast breeder reactor (LMFBR) fuel assembly duct design and LMFBR performance was investigated. As more data on irradiation-induced creep and swelling became available, the predicted creep and swelling rates increased. This leads to increases in interassembly gaps required for the same duct life. Penalties in breeding ratio, doubling times, and fuel cycle cost are the result of the increased interassembly gaps. The most significant penalties are encountered when the updated correlations on creep and swelling are used to update the duct life calculation. To compensate for increases in predicted duct dilation, the duct lifetime has to be reduced significantly.