Year
1997
Abstract
The safe and safeguardable storage of plutonium has, in the past been primarily the concern of the reprocessing plants and fuel production facilities. Following the increased drive towards plutonium disposition (and coincidentally towards MOX fuel utilisation) safeguards requirements are broadening and changing. Instruments for plutonium verification at the input and output of a store, and for in-situ monitoring within a store, are requirements of the safeguards authorities. An overview is given of two special purpose systems which have been developed for the accurate measurement of plutonium in containers entering or leaving a storage facility. Experimental data is presented showing the response and accuracy of these systems on a plutonium storage facility located within BNFL’s Thorp plant. The Product Can Contents Monitor uses passive neutron coincidence counting and high resolution gamma spectrometry to determine the content of plutonium oxide product cans prior to storage. The In-Store Plutonium Verification Monitor uses a custom built cadmium-zinc-telluride detector in conjunction with other non-radiometric systems, allowing the safeguards authorities to verify the presence of plutonium within items present in the storage facility. The design and operational features of the systems are reviewed, demonstrating their potential applicability to a wide range of plutonium storage facilities and for reconfiguration to measure alternative storage packages.