Signatures of plutonium diversion in Molten Salt Reactor dynamics

Safeguarding a Molten Salt Reactor (MSR) is an underexplored research topic. The high temperature, radiation, and corrosive nature of the fuel salt make installing and using instrumentation difficult. This study introduces a new innovative way of using the reactor's frequency response to determine if plutonium is diverted. As a low enriched uranium fueled MSR undergoes burnup, plutonium builds up in the fuel salt and increasingly contributes to fissions. As a result, the kinetic parameters, mean neutron generation time and delayed neutron fraction, evolve with depletion. These changes are large enough to be discerned as unique patterns in the MSR system frequency response. Likewise, a specific pattern is seen if there is a removal of plutonium. Given the simplicity of establishing a frequency response of an operating MSR, this method presents a breakthrough in MSR safeguards.