PLUTONIUM ROCK-LIKE FUEL BURNING IN LWR

Plutonium rock-like oxide(ROX) fuel burning in LWR has been studied. T o improve reactivity insertion accident(RIA) behavior of zirconia(ZrO2 ) type ROX(Zr-ROX) fuel PWR, small negative Doppler reactivity coeffic ient of the fuel is increased with the additives such as 24mol% ThO2 o r 15mol% UO2 in the fuel. There is also an approach of a heterogeneous core with 1/3 ROX and 2/3 UO2 fuels. From the loss of coolant acciden t(LOCA) analysis of Zr-ROX fuel PWR, the importance to decrease the la rge power peaking is shown. The ThO2 additive can make it easier to fl atten the power distribution in the core, and improve not only the rea ctivity accident behavior but also the LOCA behavior. The power flatte ning can also be achieved by reducing the content of Gd2O3 mixed in Zr O2 and adding Er2O3 in place. In the case of weapons-grade plutonium b urning, the plutonium transmutation rate in Zr-ROX fuel LWR is about 0 .9tonne/GWe/300 days, and far larger than that of full MOX LWR. The ad ditives of ThO2 or UO2 decrease the plutonium transmutation rate, yet it is still larger than that in full MOX LWR by more than 2 times. Eve n in 1/ Zr-ROX fuel core, the transmutation rate is comparable with th e full MOX case. Total amount of discharged plutonium becomes less tha n 1/ to 1/6 in these cores. (C) 1997 Published by Elsevier Science Ltd .