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Working in partnership with assay technology specialists ANTECH on the Waste Characterisation Services (WCS) Framework, we are currently undertaking a drum recharacterisation project at the Low Level Waste Repository (LLWR) in West Cumbria and have now successfully recharacterised over 500 drums.

The drums of waste were generated throughout the life of the PCM Decommissioning project, which was completed in 2019 by an integrated team comprising NSG, LLW Repository Ltd and key supply chain partners. The drums were originally characterised using the LLWR drum assay machine and assigned with a Nuclear Safety Value (NSV) to enable consignment of the drums to Sellafield for long-term storage and disposal as Intermediate Level Waste (ILW).

The characterisation undertaken by the LLWR drum assay machine was bound by several limiting factors, including the non-uniform nature of the contents, both in terms of activity levels and physical density, the radiological fingerprint and detector types resulting in low detection efficiency, and significant measurement uncertainty resulting in large error bands and uncertainty factors being applied when calculating NSVs. As such, there was an opportunity that with better assay technology the drums could be more accurately characterised and potentially diverted to lower-level waste routes, providing both cost and environmental benefits to the NDA.

ANTECH is one of the UK’s leading providers of radiation measurement equipment, measurement services and technical expertise to the nuclear industry and has developed significant advances in assay technology which allow for more accurate drum characterisation. At LLWR, we are deploying ANTECH’s Universal Drum Assay and Segregation System (UDASS), which is an integrated assay system combining high-efficiency ‘Open Detector’ measurements with a ‘Wide Range Segmented Gamma Scanner’ and ‘Tomographic Gamma Scanning’ capability.

The technology is proving to be highly effective and we are currently exceeding the original targets for resentencing PCM to Low Level Waste (LLW), with the majority of drums being shown to fall into the lower waste categories of Low Activity Low Level Waste (LA-LLW) or Very Low Level Waste (VLLW). This marks a significant achievement, with 100% of the first 500 drums being diverted away from the ILW route.