Neutron Detection Monitoring Outside Of Containment Of A Power Reactor

It is currently a priority objective of the Department of Safeguards within the International Atomic Energy Agency (IAEA) to “strengthen instrumentation capabilities for verification”, with the specific research and development need to “develop safeguards equipment to establish and maintain knowledge of spent fuel in shielding/storage/transport containers at all points in their life cycle” [1]. It has been recently demonstrated how large-area (~0.2 m 2 ) neutron detectors can monitor reactor fuel cycles at stand-off distances of up to 100 m from a research reactor by measuring the extremely low neutron fluxes that are measurable even after significant shielding and infrastructure has reduced fluxes to near background level. In particular, even at very low measurement levels, the neutron detection rate per unit reactor power has been demonstrated to be directly correlated with changes in fissile isotopic composition of the reactor core [2]. Further, the on-line re-fueling activities at the National Research Universal (NRU) research reactor, as well as the movement of legacy spent nuclear fuel at Canadian Nuclear Laboratories at the Fuel Packaging and Storage (FPS) facility, has been monitored with the same neutron detection technology at similar stand-off distances, even while the spent fuel is kept inside heavy shielding during the movement [3]. This contribution builds upon this recent work by discussing what can be seen with neutron detectors outside of containment at power reactors. The results of a neutron measurement campaign carried out at Point Lepreau Nuclear Generating Station in Point Lepreau, New Brunswick, Canada, will be presented. References: [1] IAEA Department of Safeguards, <i>Development and Implementation Support Programme for Nuclear Verification, </i>STR-386, Vienna, Austria, 2018 January. [2] B. M. van der Ende, L. Li, D. Godin, B. Sur, “Stand-off nuclear reactor monitoring with neutron detectors for safeguards and non-proliferation”, <i>Nature Communications</i>, 10:1959 (2019). [3] B. M. van der Ende, B. Sur, “Stand-Off Neutron Detection Monitoring of the Movement of Spent Nuclear Fuel”, <i>Proceedings of the 60 th INMM Annual General Meeting, </i>Palm Desert, CA, USA, 2019 July 14-18.