Bruce "B" Core Conversion

Abstract

A postulated large break loss of coolant accident (LLOCA) in the primary heat transport system will cause the relocation of fuel towards the inlet end of channels. With the current Bruce "B" Fuelling-Against-Flow configuration, this will cause fuel bundles of low bumup to move·to regions of greater neutron flux, introducing positive reactivity and increasing the power pulse. In order to improve LLOCA consequences and hence increase safety margin, Bruce Power is converting to a Fuelling-With-Flow scheme. This will result in reversal of the fuel bumup profile relative to the coolant flow direction, eliminating the positive fuel string relocation reactivity. This paper discusses some safety and implementation aspects of the core conversion that have been considered.