PLUTONIUM is created when uranium is burnt in nuclear reactors. It is highly toxic and can be used to make nuclear bombs, or to fuel reactors to generate power.

Plutonium has been extracted from UK and other reactors since the 1950s. Some 140 tonnes of it is now stored in high security vaults at the Sellafield nuclear complex in Cumbria, awaiting decisions on its fate.

An article by three German scientists in the international Bulletin of Atomic Scientists on April 17, pointed out that the store will cost UK taxpayers £73 million every year for the next century. The plutonium is “highly toxic and poses a permanent risk of proliferation,” they said.

The UK’s plutonium experiment began at Dounreay on the north coast of mainland Scotland in 1955.

It was deliberately sited as far away from population centres as possible because scientists at the time feared “a minor nuclear explosion”.

After building and running a small Dounreay Fast Reactor from 1959 to 1977 and a larger Prototype Fast Reactor from 1974 to 1994, the £4 billion programme was cancelled.

The technology, and the economics, had proved more difficult than expected.

There had also been a series of accidents and leaks – including an explosion in a waste shaft – which were often initially covered up. The shoreline and the sea near Dounreay have been contaminated by tens of thousands of radioactive particles that escaped from the plant between 1963 and 1984 – and which will never be completely cleaned up.

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Today the array of old reactors and waste facilities at Dounreay are being decommissioned. The task was originally expected to cost £4bn, but is now reckoned by the UK Government’s Nuclear Decommissioning Authority to amount to £2.8bn, with the aim of finishing in the 2030s.

A spokesperson for Dounreay said: “We keep decommissioning plans under constant review to reflect developments with such a unique and complex programme and to take account of opportunities, including advancing technology and best practice from around the world.”

According to the Nuclear Decommissioning Authority, a decision on what to do with the UK’s plutonium in the long term was a matter for government.