Quality intercomparison testing of waste package assay systems on UK nuclear sites

The independent monitoring of solid low-level radioactive waste (LLW) disposals in the united kingdom is undertaken by NNC limited on behalf of the environment agency and SEPA at the Waste Quality Checking Laboratory (WQCL) at Winfrith. A review of the potential for on-site checking of site operator's drum monitoring equipment was carried out at WQCL in 1998. As a result of this review, drums of simulated waste have been prepared and developed at WQCL. These standard waste packages form the basis of an on-going programme of on-site intercomparison tests on site operator's gamma assay instrumentation, which commenced in December 1999. The purpose of the programme is to provide the Agency with a check on site operator's waste drum measurements as part of the its ongoing monitoring programme. The use of reference drums containing defined radionuclides of known radioactivity allows the Agency to assess the adequacy of operator's arrangements for assaying drummed LLW destined for disposal in the BNFL Drigg repository in Cumbria. The waste assay systems tested to date are described and the results of the first eleven tests performed are used to compare and contrast two types of gamma assay system in common use on nuclear sites in the United Kingdom. (orig.)