A Time-Average Calculation for Bruce B Reactors Operating With Low-Void-Reactivity Fuel

Abstract

The computer code RFSP was used to perform a time-average calculation and related core characteristics calculations for Bruce B reactors, operating with either the current 37-element natural uranium (NU) fuel bundles or the CANFLEX 1-LVRF bundles. It was found that the core flux/power distributions, fuel exit burnup and fuelling rate, when operating with Low-Void-Reactivity Fuel (LVRF), remain generally similar to those of the NU core. Where there are significant differences, they tend to enhance safety margins. The main difference is, by design, the coolant-density reactivity coefficient. Other beneficial differences are in the coolant-temperature, fuel-temperature and moderator-temperature reactivity coefficients. The smaller xenon transient at reactor shutdown from high power would provide an increase in xenon-override time.