An Advanced BWR Core Design Using Circular Fuel Bundles

Abstract

Small circular fuel assemblies with a single enrichment meet the demands imposed on advanced boiling water reactor fuel. A modified circular fuel bundle can provide large improvement in the BWR core designs. It is characterized by large thermal margins and - due to the well distributed bypass water - by a large shutdown margin. Three features that are especially useful if extended load following operation and therefore high operation flexibility and simple bundle are desired. Furthermore, when compared with standard BWR 8x8-4WT fuel or even with the most recent optimized 9x9-9WT and 10xl0-4WT with/without cruciform assembly internal bypass water the circular BWR assembly design offers considerable potential for further enrichment saving or burnup increase. Extensive investigations are recommended to get full information about the neutron physics behavior of different circular assembly designs, especially about the potential reactivity gains or reload savings.