A Comparative Study on the Safety and Kinetic Parameters of UO₂ and MOX Fuel

A pin cell model is used to study and compare the safety and kinetic parameters of UO₂ and MOX fuels, when used in a PWR. The studied fuels are UO₂ of 3.9 % and 5% enrichment, and mixed uranium plutonium from reactor recycle and weapon grade sources each with two PuO₂ contents, 4% and 6%. The safety parameters studied are the Doppler coefficient, the moderator temperature coefficient, and the soluble boron worth. The results showed that the MOX fuel with reactor grade plutonium has the highest Doppler and moderator temperature coefficients, while UO₂ has the highest boron worth. Burnup calculations were performed to study the change in the multiplication factor, the effective delayed neutron fraction, and the neutron mean generation time. The reactivity of UO₂ showed larger decrease with burn up than both types of MOX fuel. The delayed neutron fraction for UO₂ decreased with burnup, while it increased for MOX fuel. The neutron generation time increased generally with burnup, with the highest values for UO₂ . The results are in agreement with previous studies