Fuel Management Studies for the Pickering NGS B Reactor with Reduced Adjuster Loading

Abstract

The adjuster rods in Pickering NGS B provide reactivity for xenon override, and to allow operation for limited time when fuelling is unavailable. The adjusters also help to shape the power distribution. However, the adjuster reactivity load produces a significant burnup penalty. In Pickering, the saving in replacement energy cost from having sufficient xenon override capability to recover from a reactor trip is smaller than the additional fuelling cost caused by the adjuster burnup penalty. This paper discusses various methods of operating the Pickering NGS B reactors with a reduced adjuster loading. This study concluded that operating Pickering NGS B with only five of the original 21 adjusters in the core, in conjunction with a four-and eight-bundle shift fuelling scheme is the best option.