Multiple recycling of plutonium in advanced PWRs

The influence of the moderator-to-fuel ratio in MOX fueled PWRs on the moderator void coefficient, the fuel temperature coefficient, the moderator temperature coefficient, the boron reactivity worth, the critical boron concentration, the mean neutron generation time and the effective delayed neutron fraction has been assessed. Increasing the moderator-to-fuel ratio to values larger than three, gives a moderator void coefficient sufficiently large to recycle the plutonium at least four times. Scenario studies show that four times recycling of plutonium in PWRs reduces the plutonium mass produced with a factor of three compared with a reference once-through reactor park, but that the americium and curium production triple. If the minor actinides and the remaining plutonium after four times recycling are disposed of, the reduction of the radiotoxicity reaches only a factor of two. This factor increases to five at the maximum when the plutonium is further recycled. Recycling of americium and curium is needed to further reduce the radiotoxicity of the spent fuel. 4 refs