Neutronics study of a subcritical system driven by external neutron source for 99Mo production

Abstract

A subcritical system with the Low Enriched Uranium (LEU) solution was proposed to produce 99Mo, which is driven by an external D–T neutron source. The neutronics model of the subcritical system is approximately a concentric cylindrical structure with the maximum radius and height of the system as limited to 100 cm and 150 cm, respectively. The materials and dimensions of the zones were designed based on neutronics analysis including the sub-critical multiplication factor ks and distribution of neutron flux to achieve high production of 99Mo, as well as to keep the system in a safe and deep sub-critical state (i.e. 0.90<ks<0.95). With intensity of neutron source as 5 × 1013 n/s, the yield of 99Mo in the system can reach to 167 Ci/day, which could be used for around ten thousand nuclear medical procedures.