Radioactive sludge has beenremoved from the world’s oldest nuclear fuel pond for the first time.
The operation is a historic achievement in the clean-up of the decommissioned Sellafield nuclear power plant in Cumbria.
The Nuclear Decommissioning Authority (NDA) said that the project was being delivered 10 years ahead of schedule and for half the £200M expected cost.
Sludge, formed from decaying nuclear fuel, natural growing algae and other debris, has accumulated in the pile fuel storage pond at Sellafield during its 65-year lifespan. The NDA said that this must be removed so the facility could be safely decommissioned.
It said that following years of planning and preparation, the first 500l drum containing the mud-like substance had been moved to an encapsulation plant. It will then be grouted – rendering the waste passively safe – and processed into a storage state, ready for final disposal in a geological disposal facility.
The initial sludge removal involves pumping the material into a purpose-built treatment plant next to the pond, before transfer to the drum filling plant.
The authority said that it will take several years to remove all of the sludge in the pond.
A 10-year project to dewater the pond will start in 2019, while sludge is still being removed.
The 100m long pond was originally used to store nuclear fuel used to make atomic weapons.
All the bulk stocks of fuel have now been removed, leaving sludge as the biggest remaining radioactive hazard.
The pile fuel storage pond is one of the four ageing facilities at Sellafield that the NDA has prioritised for clean-up.
NDA chief executive John Clarke said: “This pond was not designed with decommissioning in mind, and therefore we welcome this work by Sellafield Ltd to begin safe removal of sludge, which is a key step in making the site safer.
“The removal of the sludge contributes to achieving our overall goal of risk reduction by placing radioactive material and substances under more modern storage arrangements until it is ultimately moved to a geological disposal facility.”
Sludge accounts for one third of the pond’s remaining radioactive content, after 70% was removed earlier this year with the completion of fuel exports.
Sellafield Ltd head of legacy ponds Dorothy Gradden said: “There’s lots of hard work ahead to get all the sludge out, but this is another key moment for our decommissioning mission and another sign of visible progress. This is one of the first examples of a legacy facility producing a waste ready for a geological disposal facility – it’s a cradle-to-grave solution.
“With the start earlier this year of bulk fuel and sludge removal from our other legacy pond, we’re now ‘firing on all cylinders’ in reducing the hazard and risk in these legacy facilities and making them safer places.”