Characterising the Radionuclide Fingerprint of an Advanced Gas-Cooled Nuclear Power Reactor

Radionuclides are monitored in the atmosphere for the signatures of nuclear explosions, as part of the verification of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Civil nuclear facilities, such as Nuclear Power Plants (NPPs) and Isotope Production Facilities (IPFs) are sources of anthropogenic radionuclides in the atmosphere and these signatures are sometimes indistinguishable to those of a nuclear explosion. In order to improve the understanding of civil radionuclide-emitting facilities and their impact on the International Monitoring System (IMS) of the CTBT, a group of scientists from the UK, US and Sweden are collaborating with EDF Energy UK to measure radionuclide emissions from an Advanced Gas-cooled Reactor (AGR) nuclear power station. Emissions are being measured at the source, via a stack monitor and high-resolution gamma spectrometry measurements of filters and also at tens of kilometres away via three sensitive radioxenon atmospheric samplers. The timing, isotopic composition, activity magnitudes and other release parameters of interest are investigated, to improve the discrimination between a civil radionuclide release and an explosive nuclear test. This paper outlines the work of the Xenon and Environmental Nuclide Analysis at Hartlepool (XENAH) collaboration, describes the equipment fielded and provides initial results from each measurement campaign.