Provision of NDA instrumentation for the control of operations on plutonium finishing and waste plants at the Sellafield nuclear fuel reprocessing facility

On BNFL's Sellafield site a significant number of major plants are involved in the handling, processing and storage of plutonium in various forms including nitrate, oxide and mixed oxide (MOX). Other plants in operation or under construction treat and prepare for storage, plutonium bearing wastes in the form of plutonium contaminated materials -- PCM (transuranic waste -- TRU) or low level waste. Concurrently, a number of old plutonium handling plants are being decommissioned. The safety and cost effectiveness of these widely varying operations has been ensured by the development and installation of a wide range of special radiometric instrumentation. These systems based on a range of neutron counting and high resolution gamma spectrometric techniques -- singly or in combination -- enable BNFL to maintain a detailed and comprehensive picture of the disposition of plutonium within each plant and across the site. This paper describes an overview of the range of plant and paper prove waste measurement systems in this context, highlighting the specific roles of the Plutonium Inventory Measurement System (PIMS) for real time accountancy and the Decommissioning In-Situ Plutonium Inventory Monitor (DISPIM) for material control during decommissioning