Theses and Dissertations Collection

A Nuclear Criticality Safety Evaluation was performed for the proposed FLiNaK-UF4 fuel salt preparation and handling processes to be used in the Molten Salt Nuclear Battery concept. The fuel salt is a mixture of purified eutectic LiF-NaF-KF (respectively 46.5, 11.5, and 42 mole %) and UF4 fuel with a fuel loading of 18 mole % UF4 and enrichment of 19.75 mole % 235U. The DOE-STD-3007-2017 technical standard was followed while performing this evaluation to be compliant with the ANSI/ANS-8 series of criticality safety standards. The Monte-Carlo nuclear code Serpent 2, version 2.1.31, was used to perform the calculations for this evaluation to estimate the effective neutron multiplication factor, keff, of the processes under normal and credible abnormal conditions. The results of this evaluation show that the processes will remain subcritical under both normal and credible abnormal conditions by not exceeding an upper subcritical limit of 0.95. The maximum keff under normal conditions was 0.58737 ± 0.00085 (95 % confidence) during the transportation of the fuel salt vessels. The maximum keff under abnormal conditions was 0.82013 ± 0.00134. Any controls and assumptions used for these processes are discussed.