Effect of $$^{{\textbf{37}}}{\textbf{Cl}}$$ enrichment on neutrons in a molten chloride salt fast reactor

Abstract

A molten chloride salt fast reactor (MCFR) is well suited to fuel breeding and the transmutation of transuranium (TRU) elements owing to its advantageous features of fast neutron spectrum and high TRU solubility. However, the neutron absorption cross section of $$^{35}{\hbox {Cl}}$$ is approximately 1000 times greater than for $$^{37}{\hbox {Cl}}$$, which has a significant impact on the neutron physical characteristics of a MCFR. Based on an automatic online refueling and reprocessing procedure, the influences of $$^{37}{\hbox {Cl}}$$ enrichment on neutron economy, breeding performance, and the production of harmful nuclides were analyzed. Results show that $$^{37}{\hbox {Cl}}$$ enrichment strongly influences the neutron properties of a MCFR. With natural chlorine, $$^{233}{\hbox {U}}$$ breeding cannot be achieved and the yields of S and $$^{36}{\hbox {Cl}}$$ are very high. Increasing the $${^{37}{\hbox {Cl}}}$$ enrichment to 97% brings a clear improvement in its neutronics property, making it almost equal to that corresponding to 100% enrichment. Moreover, when $${^{37}{\hbox {Cl}}}$$ is enriched to 99%, its neutronics parameters are almost the same as for 100% enrichment. Considering the enrichment cost and the neutron properties, a $$^{37}{\hbox {Cl}}$$ enrichment of 97% is recommended. Achieving an optimal neutronics performance requires 99% $$^{37}{\hbox {Cl}}$$ enrichment.