Design and analysis of an innovative pressure tube light water reactor with variable moderator control

An innovative light water reactor constructed as a multitude of modular, horizontal fuel channels has been proposed. The basic novelty of the proposed design is an implementation of the “breed & burn” mode of operation by a dynamic variation of the moderator content in the core. This paper describes the novel reactor core design and explores the physical principles underlying its operation. Initially, a single fuel channel assembly was analyzed in order to evaluate the impact of the moderator variation on the reactivity and “breed & burn” processes. At the second stage, a full core model was analyzed, demonstrating a possibility of a realistic fuel management scheme with on-power moderator addition. The BGCore Monte-Carlo based depletion code was used for the analyses. It has been shown that the proposed design has a potential to increase the fuel utilization, attain negative reactivity coefficients and reduce the excess core reactivity during the power operation. The physical observations, presented and discussed in this paper, provide an interesting research lines for future investigation and continuous design developments.