Fuel residence time in BWRs with nitride fuels

This paper presents a neutronics study of a BWR core with uranium nitride fuels. Replacing the standard UO2 fuel with UN or UN-ZrO2 allows for a higher uranium content, which leads to an increase of the in-core fuel residence time. With the nitride fuels, the total void worth increases and the efficiency of the control rods and burnable poison deteriorates. Taking into account the higher amount of burnable poison needed at the beginning of life, the in-core fuel residence time increases by about 1.4 year comparing to UO2 fuel with the same enrichment. This implies 1.4% higher availability of the plant and it is therefore of economic interest to the nuclear power plant operators. A similar increase of the fuel in-core lifetime in a UO2 core could be reached by an increase of the average enrichment of the oxide fuel by roughly 1%.

► This paper presents a neutronics study of a BWR core with uranium nitride fuels.
► Replacing the standard UO2 fuel with nitride increases the cycle length by 1.4 year.
► The yearly consumption of U-235 is about the same in the oxide and the nitride core.
► The efficiency of the thermal absorbers deteriorates in the nitride core.