TODAY Berkeley nuclear site became the first commercial power station in the UK to seal up its reactors before the final stage of decommissioning.

It is a major milestone in the nuclear industry and one that was celebrated with a door closing ceremony led by Dame Janet Trotter, Lord Lieutenant of Gloucestershire.

The two reactors will no longer be known by that name but as ‘safestores’ and will be locked up and sealed until 2074 when the building can be dismantled, completing the decommissioning process which began in 1989.

Sara Johnson, the Nuclear Decommissioning Authority’s (NDA) head of programme, said: "This is a hugely significant achievement, not just for the site but for the UK nuclear industry as a whole, demonstrating the progress being made in decommissioning."

Berkeley Power Station was the first built in the UK to produce electricity commercially and its two natural uranium fuelled reactors came into service in 1962.

Penny Wride, chairwoman of the Berkeley Site Stakeholders Group (SSG), said the station had been a huge part of the Berkeley community.

"We have lived with the site for around 50 years and it has never been a problem to us. In fact schools have benefited by doing science projects there, the community has received many grants from Magnox and it has employed many highly skilled workers."

Mrs Wride said she was thrilled that a UK first was happening in the town.

"It is fantastic and proves to the world Berkeley is doing it first. It is such a major achievement."

At the ceremony this morning children from Berkeley and Sharpness Primary Schools put a time capsule into the reactors to be retrieved in around 60 years time.

They had included school jumpers, stamps, football cards, a mobile phone, today’s Gazette newspaper, a memory stick with videos of the children and letters they had written about their lives in 2010.

Head teacher of Berkeley Primary, Debbie Marklove, said: "It is very exciting for the children because hopefully they will be around when they are opened again and it will be memorable for them."

Dame Janet said she was having her "Dr Who moment of the year" as she officially started the safestore closing ceremony, in which the doors on the huge reactor were slowly closed to flashing lights and music.

Over 84,000 fuel elements were defuelled between 1989-1992, which resulted in 99 per cent of the radioactivity being removed from the site.

The number of staff on the site will remain at the same level for several years to come, before it is gradually reduced.