Conceptual design of a high neutron flux research reactor core with low enriched uranium fuel and low plutonium production

Abstract

Research reactors for radioisotope production, fuel and material testing and research activities are designed, constructed and operated based on the society's needs. In this study, neutronic and thermal hydraulic design of a high neutron flux research reactor core for radioisotope production is presented. Main parameters including core excess reactivity, reactivity variations, power and flux distribution during the cycle, axial and radial power peaking factors (PPF), Pu239 production and minimum DNBR are calculated by nuclear deterministic codes. Core calculations performed by deterministic codes are validated with Monte Carlo code. Comparison of the neutronic parameters obtained from deterministic and Monte Carlo codes indicates good agreement. Finally, subchannel analysis performed for the hot channel to evaluate the maximum fuel and clad temperatures. The results show that the average thermal neutron flux at the beginning of cycle (BOC) is 1.0811 × 1014 n/cm2-s and at the end of cycle (EOC) is 1.229 × 1014 n/cm2-s. Total Plutonium (Pu239) production at the EOC evaluated to be 0.9487 Kg with 83.64% grade when LEU (UO2 with 3.7% enrichment) used as fuel. This designed reactor which uses LEU fuel and has high neutron flux and low plutonium production could be used for peaceful nuclear activities based on nuclear non-proliferation treaty concepts. Keywords: Core design, High neutron flux research reactor, Neutronic, Thermal hydraulic, Deterministic neutron transport and Monte Carlo neutron transport