Burnup analysis of VVER-1000 reactor with MOX refueling options
Аннотация
The present work examined the burnup processes in the VVER-1000 reactor core loaded with UO2 and MOX (Mixed Uranium-Plutonium Oxide) fuels. MOX fuel was loaded into the 1/3, 1/2 and 2/3 of the reactor core. The burnup processes simulated by using GETERA-93 code with the nuclear data library BNAB-93. It was assumed that the MOX fuel uses plutonium separated from the spent fuel of the VVER-1000 reactors. This work considers the operation of the reactor in the mode of partial reloading of the UO2 and MOX fuel. The fuel campaign included three cycles for the both UO2 and MOX fuel and the duration of one cycle was 411 days. The multiplication factor, effective delayed neutron fractions and variations of isotopic composition in the both UO2 and MOX fuel were analysed. The decreasing of the multiplication factor in the cases of presence of MOX fuel was comparatively slower than that in in the case of the absence of MOX fuel. The effective delayed neutrons fraction was reduced by 15-30% with an increase in the proportion of MOX fuel in the reactor.