Experiments and Analyses on Sodium Void Reactivity Worth in Uranium-Free Fast Reactor at FCA

Abstract

A uranium-free fast reactor was simulated at FCA in order to examine the prediction accuracy for sodium void effect of plutonium burning fast reactors. Material sample worth for plutonium and B4C was also measured to compare its prediction accuracy with that for the sodium void reactivity worth. It was found that an axial distribution of plutonium sample worth and the central B₄C sample worth for various kinds of ¹⁰B enrichment were precisely calculated by the conventional calculation method for fast reactors with 70-group structure. The sodium void reactivity worth was, however, poorly predicted especially for the non-leakage term. This discrepancy seems to be caused by the peculiar energy breakdown of the non-leakage term in the uranium-free fast reactor.

KEYWORDS:

• FCA reactor plutonium burning fast reactor
• uranium-free fuel
• critical experiments
• sample worth
• sodium void reactivity
• B₄C
• perturbation theory
• JENDL-3.2
• reactivity worth