Analysis of reactor with inserted Chloride salts

Abstract Chloride salts are promising fuel carriers for fast-spectrum molten-salt reactors, but current chlorine nuclear data introduce significant uncertainties. To support their validation, critical experiments were performed at the thermal spectrum LR-0 reactor using several chlorine-containing compounds inserted into a benchmark core. Accompanying calculations with ENDF/B-VII.1, ENDF/B-VIII.0, ENDF/B-VIII.1, JEFF-4 and JENDL-5 generally underestimate reactivity, in some cases by more than 400 pcm. Sensitivity analysis identifies 35Cl capture, scattering and (n,p) reactions as the dominant contributors to the observed discrepancies. The results highlight the need for improved chlorine evaluations and provide new integral benchmarks for validating nuclear data used in chloride-salt reactor designs.