Power Monitoring of Advanced Reactors with Short-Lived Activation Products

The emergence of advanced reactor designs challenges the international safeguards community. Unique characteristics and combinations of materials and neutron regimes can avoid traditional safeguards methods preventing the timely detection. However, advanced reactors provide new avenues for detection through the use of radionuclide signals that are not present in light water reactor technologies. The relative measurement of activation products within the reactor core can provide inspectors with near real-time operating characteristics. In reactors that utilize a chloride species as coolant, the fast neutron reaction 37Cl(n,p)37S can be exploited to detector reactor operations. The activation product 37S has a 5 minute half-life and produces a 3.1 MeV gamma-ray during decay. The short half-life and large inventory allow a dedicated, non-intrusive ex-core radiation detector to measure the relative gamma ray intensity to determine operating characteristics of the advanced reactor design.