The Shepley Decontamination Services (SDS) Specialists were engaged to undertake a series of sampling and characterisation tasks at the Chapelcross site as part of the site wide Intermediate Level Waste characterisation program. These included the sampling of reactor desiccant driers, pond sludges and the internal resins of a Zeolite pond skips. This sampling work was required to be undertaken while the Zeolite skips remained in-situ 8m under water, to ensure shielding was maintained at all times.
Bespoke concept tooling was designed and an extensive trialling and test rig development program was conducted to develop the specialist tools. A full scale test rig was constructed offsite at Numech Ltd’s facility in Workington. This was used to prove the methodology and also for customer acceptance and safety case approval trials. Once the methodology and tooling had been comprehensively tested and the methodology trialled, the SDS team carried out the underwater sampling of the Zeolite skips. After first drilling through the skip lids, a sample was retrieved and packaged underwater before the skip was semi-remotely re-sealed. The work also included the sampling of the CO2 reactor desiccant driers. A specialised blister bag arrangement was positioned over the flange access ports by the SDS team whilst wearing a breathing air system; this allowed the flanged access on a number of desiccant drier towers to be opened in a controlled and safe manner. The alumina desiccant held within was then sampled, packaged and sent for analysis and characterisation. Additionally, a number of samples of sludges were taken from Sludge Skips within the pond and from two sludge detention tanks.