Radiation risk reduced as two million litres of liquid nuclear waste pumped from 50-year-old store

The Sellafield clean up operation has passed a significant milestone, after pumping two million litres of liquid out of one of the world's oldest nuclear waste stores. 

Constructed in the 1960s, the Magnox Swarf Storage Silo (MSSS) was key to supporting Magnox nuclear power generation in the Britain. Spent fuel from plants all around the UK was sent to Sellafield so that it could be recycled in the Magnox Reprocessing Plant.

However, in order to avoid power shortages during the miners’ strikes nuclear plants around the country increased power generation – meaning that spent fuel arrived at Sellafield at a faster rate than the reprocessing plant could properly handle it.

Fuel cladding, known as swarf, is stored under water in the 22 individual compartments within the silo. The water, used as a radiation barrier, has been in the store so long that it has become nuclear waste too.

Engineers designed a system to purge the water by pumping it out of the store, using a chemical process to remove the radioactivity from it, with fresh water replacing it in the store, making the plant safer and the job of receiving the swarf easier.

In less than five years since the programme to remove liquid effluent from the silo started, two million litres has been pumped out.

Head of the MSSS, Chris Halliwell, said: “The radioactivity we’ve removed and treated arose from several hundred tonnes of uranium fuel which during its lifecycle would have generated enough electricity to power over 11 million homes for a year.

“It was never built with decommissioning in mind and safely removing the liquid and solid nuclear wastes requires some ingenious engineering. We have now successfully removed liquid waste containing 10,000 terabequerels of radioactivity from the store - which equates to locking away roughly the same amount of nuclear waste discharged to sea in the Japanese Fukushima accident. Completion of this liquor transfer from the MSSS is an important step towards emptying the silos, processing the waste and safely decommissioning this legacy plant.”

The next stage will be to remove the solid waste inventory from the facility, process it and encapsulate it for safe long term storage. Three silo emptying plants are being built, the first of which will be brought to the Sellafield in a few months time. This will undergo testing before being available for solid waste retrievals in 2017.