Plutonium recycling in a full-MOX 900-MW(electric) PWR: Physical analysis of accident behaviors

The feasibility of 100% mixed-oxide (MOX) fuel recycling in a standard pres surized water reactor (PWR) is explored. The plutonium neutronic specificit y is analyzed and compared with uranium. The objective is to identify the g eneric aspects that could lead to current PWR design modifications. The plu tonium isotopic composition was taken as a parameter. Accidents dealing with a change of the moderator density are of particular interest (especially considering that control worth is significantly reduce d with MOX fuel). Study of core global draining leads to the following conc lusion: Only very poor quality plutonium fuel (low fissile content) cannot be used in a 900-MW(electric) PWR because of a positive global draining rea ctivity effect. Study of the cooling accident (increase of moderator densit y) proves that the spurious opening of a secondary side valve is the most p enalizing scenario in the case of MOX fuel utilization. The core reactivity was controlled in this study by 57 control rod clusters made of B4C rods h aving a 90% B-10 content and a hafnium clad The hypothetical return to crit icality depends on plutonium isotopic composition. But the core is kept sub critical for all isotopic compositions provided an increase of the soluble boron B-10 content up to a value of 40%. No major obstacle to the 100% MOX 900-MW(electric) PWR feasibility was found.