Impact of Fuel Enrichment on Key Naval Reactor Characteristics and Non-Proliferation Concerns

Abstract

This work reports on a notional compact naval reactor core running at 50 MWt full power—designed to investigate core life, reactivity margins and plutonium inventory for different levels of enrichment. A simplified computer model was constructed with the OpenMC neutron transport code and coupled to ONIX to calculate depletion of the initial fuel load—uranium dioxide mixed with gadolinia. It is shown that a notional low enriched uranium naval core could sustain criticality for 5–7 years at full-power and overcome xenon poison transients. Self-shielding of the burnable poison has been found to be significant in the radial direction and should be considered in such core design. Negative Doppler and moderator coefficients have been found for the low enriched cores. The plutonium inventory of the spent fuel produced at the end of life as a function of enrichment is also investigated. This study bears direct implications for the nonproliferation regime by suggesting that it may be possible to reduce the technical incentives for the use of highly enriched uranium on naval reactors.