UK's earliest nuclear power stations
Back in the 1950s, Calder Hall, on the Sellafield site in Cumbria, was the first in a series of Magnox nuclear power stations, so-called because the fuel cans were made of magnesium alloy. Eleven stations were eventually built, producing 10 per cent of Britain’s electricity.
These early nuclear power stations are all now closed. The last to stop generating electricity was Wylfa in Anglesey, north Wales, which had been producing power for almost 45 years by the time of its closure in December 2015.
While operating, fuel was loaded into reactors as required, and a corresponding quantity of spent fuel was removed and transferred to Sellafield for reprocessing, following a period of storage on site to allow for the cooling and decay of fission products.
More than 5 million Magnox fuel elements were manufactured in total, almost all destined for the UK. Magnox-type plants were also built in Italy and Japan.
The Magnox sites in the UK have now all moved into a phase of decommissioning, which begins with removal of the remaining spent fuel, referred to as “defueling”.
Fuel is removed from the reactors and then stored on-site, a process lasting several years. As was the case in the generation phase, ultimately this fuel is transported off site in flasks to the Sellafield site in Cumbria for reprocessing.
Once the fuel has been sent off site, 99% of the site's radioactive inventory is removed. It is the most important hazard reduction activity on our reactor sites and a crucial step in the transition towards decommissioning.
Progress in defueling
Of the 11 UK sites that host Magnox reactors, only 2 are still defueling:
- Wylfa on Anglesey will complete in 2018
- Calder Hall on Sellafield site is scheduled to complete in 2019
Both Wylfa and Calder Hall sites continue to benefit from the learning gathered from the other Magnox sites that have already defueled.
Magnox Ltd and Sellafield Ltd are working together to ensure that the defueling and reprocessing is delivered in a safe and compliant manner, as soon as practicable, with least cost to the UK taxpayer.
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