WETP’s work is done

October 26, 2011

The Waste Encapsulation Treatment Plant (WETP) at RSRL Winfrith has now completed its mission. The plant was specifically designed and built by the contractor, Nuvia, to receive and process sludge from the SGHWR (Steam Generating Heavy Water Reactor). It took more than five years to empty the tanks and stabilise the sludge in cement in 500-litre stainless steel drums.

Operations began in May 2005 with the opening of WETP by Dr Ian Roxburgh, then CEO of the Nuclear Decommissioning Authority. The last encapsulated sludge drum was transferred to the site’s Treated Radwaste Store (TRS) in April 2010. During the plant’s lifetime, a total of 1,068 encapsulated sludge drums were produced and are now being stored pending final disposal off site.

As might be expected, this major work was not without its difficulties, as RSRL project manager, Cliff Strange, explained. “All went reasonably smoothly, with production peaking during June 2008 at 100 sludge drums a month, until we reached the final stages of the recovery, when we discovered a quantity of dense material in the bottom of the tanks. It was mostly silica and generally referred to as ‘sandy material’. The recovery of this unexpected material required different methods and a fair bit of innovation.”

Nuvia, in conjunction with RSRL, developed a process to recover the sandy material using an industrial vacuum pumping system – called Big Brute – and encapsulate it in 40 litre containers, within prepared 200 litre waste drums. The sandy material was recovered in 20kg batches and mixed with a premixed grout in a temporary encapsulation rig, also developed by Nuvia. In all, 178 drums were filled using this process.

The final piece of the decommissioning jigsaw is the demolition of WETP. With its work to encapsulate the sludge once stored at EAST now done, the demolition contractor is currently working on the soft strip of the building. WETP demolition is scheduled for completion by the end of the year. The successful completion of the recovery and encapsulation of SGHWR sludges marks a major milestone in the restoration of the Winfrith site.

For more information please contact Emma Burwood, RSRL Communications, Winfrith