Use of an ISOCS-based Waste Assay System for Decommissioning Waste at Trawsfynydd - 19526

摘要

Magnox UK Ltd. are decommissioning the former Magnox nuclear power stations in the UK, a process that generates a significant amount of radioactive waste, much of it in the Low Level or Very Low Level categories. It is therefore necessary to perform radiometric assay of the decommissioning waste in order to determine the disposal route and to identify items of waste that are Out of Scope of regulatory control and can therefore be free-released. They have recently commissioned a Canberra On Site Assay System (OSAS) for this purpose. OSAS is a high-resolution gamma-ray spectrometry based waste assay system, which makes use of the ISOCS methodology in order to perform the necessary efficiency calibration of the system for use when assaying the various different containers for the decommissioning waste employed at Trawsfynydd: 210 litre drums, Dolav boxes, wheeled bins and Pac-Tec bulk bags of heavier waste. This publication describes the approach used by Magnox in the processing of the decommissioning waste at Trawsfynydd. It also presents details of the OSAS system and how it was calibrated along with the results from the proof testing of the new system, involving comparison with the results from the assay of waste previously assayed using other monitors.