Analysis of the influence of different arrangements for ZrH moderator material on the performance of a SFR core

Different arrangements for the development of a fuel element design with reduced sodium void achieved by the use of the moderating material ZrH are investigated. In the study, the sodium void effect and the major feedback coefficients are analyzed. Besides the feedback coefficients, the influence on the operational parameters like neutron flux distribution, power distribution, and burnup distribution is investigated for the different possibilities of arranging the moderating material in the fuel element. Additionally, the fuel cycle parameters—breeding and minor actinide production—are analyzed. For a first evaluation of the behavior during transients, the influence of temperature changes in the ZrH is studied.

► Using distributed moderator opens the possibility of designable feedbacks. ► Fine distributed moderator has no influence on power and burnup distribution. ► Location of the moderator has no influence on the feedback coefficients. ► Moderator has only small influence on breeding and minor actinide production.