Radiotoxicity hazard of U-free PuO2+ZrO2 and PuO2+ThO2 spent fuels in LWR

The radiotoxicity hazard of U-free Rock-like oxide: ROX (PuO2+ZrO2) and Tho rium oxide: TOX (PuO2+ThO2) LWR spent fuels is investigated and radiotoxici ty hazard of MOX spent fuel is considered as a reference case. The long-ter m ingestion radiotoxicity hazard of ROX spent fuel is one third and nearly one fourth of that of TOX and MOX spent fuels, respectively. This is becaus e the discharged Pu and long lived Np in ROX fuel is less than that of TOX and MOX fuels. In TOX fuel, discharged Pu and MA are lower than that of MOX fuel but the long-term radiotoxicity hazard of spent fuel is nearly the sa me as MOX spent fuel. At the cooling 10(5) years, the radiotoxicity hazard of TOX spent fuel is approximately ten and three times higher than that of ROX and MOX spent fuels, respectively due to higher toxic contribution of T h-229 in TOX spent fuel. (C) 2000 Elsevier Science Ltd. All rights reserved .