Physical optimal design and analysis of 99Mo production in new type molten salt fast reactor

Abstract

Background99Mo has important applications in nuclear medicine field. It can be produced in a 235U fission reactor with high yield and specific activity.PurposeThis study aims to optimize the core parameters of new type molten salt fast reactor, and then analyze the production of 99Mo based on the optimized core.MethodsThe Standardized Computer Analyses for Licensing Evaluation Version 6.1 (SCALE6.1) was used to perform the critical calculations, by analyzing the influence of geometry parameters on keff (effective proliferation factor) and temperature coefficient of reactivity, the geometry parameters of the core were determined, and then the extraction position of fuel target in the production of 99Mo was determined by analyzing the neutron energy spectrum and mean microscopic fission cross sections of 235U. Finally, the output of 99Mo in fuel target was calculated.ResultsThe results show that the keff can be increased while the coolant temperature coefficient be decreased by increasing the radius of fuel element and reducing the radius of fuel cell appropriately. When the fuel element container wall thickness is 0.1 cm, fuel element radius is 3.5 cm, fuel cell radius is 5 cm, active area radius and reflector thickness are 63 cm and 100 cm respectively, the operating life of core reaches 32 months and the temperature coefficient of reactivity is -1.615×10-5 K-1, which ensure the inherent safety of reactor core. Selecting the outermost fuel element as the fuel target for 99Mo production can increase the yield of 99Mo. The 99Mo annual output exceeds 6.25×1016 Bq and specific activity exceeds 2.77×1015 Bq∙g-1 when the extraction cycle of fuel target is 7 days.ConclusionsTherefore, the high yield and purity of 99Mo can be obtained by producing 99Mo in the new type molten salt fast reactor.

Keywords

• new type molten salt fast reactor
• 99mo radioisotope
• reactivity temperature coefficient