Discharges down in Sellafield decommissioning plant

Discharges from one of Sellafield’s priory decommissioning projects have reduced by almost 100% because of the success of a Local Effluent Treatment Plant (LETP).

Tony Calvin, Pile Fuel Storage Pond (PFSP) Facility Manager, Sellafield Ltd said: “One of the side effects of decommissioning redundant nuclear plants is often that radioactive discharges increase, however, we’re doing just the opposite in the Pile Fuel Storage Pond.”

“The level of activity in the pond water had increased over the years due to the corrosion of historic fuel held within the pond. Work to retrieve radioactive sludges and fuel from the pond would potentially have added to this increase. We therefore had to come up with something to minimise discharges to the environment and make it a safer place for our workforce, and the LETP does what it says on the tin.”

The 20 tonne LETP was lowered in to the 60-year-old PFSP back in 2006 to control radiation levels in the pond water itself and to reduce radioactive discharges from the plant.

Following extensive commissioning and testing, the LETP started to operate in 2008 and has effectively eliminated discharges of the radioactive metal caesium. The unit has successfully operated for 4 years and doses to the workforce working around the pond have also been reduced.

The LETP is capable of cleaning up 125m3 of pond water a day. The bespoke unit filters out radioactive contaminants from the pond water using a two stage filtering process. Firstly the water passes through a sand bed filter and secondly through ion exchange cartridges.

The PFSP is the world’s largest open-air pond and Sellafield’s oldest, having begun operating in 1952. It was built to store and cool spent nuclear fuel from the Windscale Piles and was later modified to accept Magnox fuel from Calder Hall. Decommissioning work is concentrating on retrieving the fuel and radioactive sludges to empty the pond.

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