FEASIBILITY STUDY OF THE CONVERSION OF IRT-DPRK RESEARCH
REACTOR FROM HEU TO LEU FUEL

Democratic People’s Republic of Korea (DPRK) currently uses 80 wt% 235U enriched fuel in their research reactor (8MWth-IRT), which is not under the International Atomic Energy Agency (IAEA) safeguards because DPRK retreated away from the treaty on the non-proliferation of nuclear weapons (NPT). Conversion of fuel in nuclear research reactors from highly enriched uranium (HEU) to low enriched uranium (LEU) is a global trend for meeting the objectives of nuclear non-proliferation. A computational feasibility study was conducted to convert DPRK’s 8MWth-IRT reactor fuel from HEU to LEU. Comparisons were made of the reactor performance, such as neutron flux, effective neutron multiplication factor, neutron reactivity, temperature dependent coefficients, reactor operation time, etc., with the current 80 wt% 235U enriched HEU fuel type (UAl: uranium aluminum alloy) and potential 19 wt% 235U LEU fuel types (UAl and 𝑈3𝑆𝑖2: uranium silicide). Potential proliferation risk of plutonium was assessed and compared by performing fuel depletion simulation for both types of 235U enrichments (HEU and LEU fuel). The neutronic simulation and analysis of fuel depletion, buildup of fission products and other actinides, including plutonium were carried out using the Monte Carlo radiation transport code, MCNP6.2. The MCNP6.2 code was selected because it is suitable to model complex geometry of the reactor fuel as well as it uses very accurate energy dependent neutron interaction point cross sections. Two potential LEU fuels showed suitable performance with sufficient excessive reactivity and the thermal neutron flux to replace the HEU fuel from a neutronics perspective. These results can form the basis for further research regarding the peaceful use of nuclear material and for the discussion on the nuclear weapons denuclearization of DPRK.