Atomic age's biggest hurdle
In the third of his series on the nuclear industry, Paul Brown examines the problem of Dounreay's decommissioning
Wednesday August 25, 1999
Taking a fast breeder nuclear reactor to bits is as difficult as building it in the first place, especially since the scientists who filled it with sodium and plutonium never gave the problem of demolition a thought.
As schoolchildren used to learn in their first chemistry lesson, even a tiny speck of sodium reacts violently on contact with water. Imagine what a mess 1,500 tonnes of it could make if it leaked, laced with radioactivity, into the rain soaked Scottish countryside.
Preventing this happening is one of the challenges of decommissioning the two fast breeder reactors perched on the edge of the seashore at Dounreay on the northern coast of Caithness. There is an old joke in the anti-nuclear lobby that the reactors were placed on the top of a cliff so that if anything went wrong they could be tipped in the sea. The reality is that the site was chosen for its remoteness so that if the worst happened the fewest number would be killed.
The scientists involved in dismantling the reactors are not operating with a free hand, or the public goodwill enjoyed by its builders in the golden age of nuclear power, but face stern critics in government regulators and the environment lobby.
It was only two years ago that 143 recommendations to tighten safety at Dounreay were made by the Nuclear Installations Inspectorate - the most damning official report ever made about a British scientific facility.
Recovering from that blow, and the subsequent government decision to close the site's reprocessing plant and redirect the efforts of its 1,600 staff to dismantle the entire complex, has been a tough assignment for the new site director, Peter Walsh.
He said: "Nothing physical has happened since that report but we have changed the culture. We are planning to take the place apart in a businesslike way, with safety our first priority."
Public relations has been stepped up, with coach parties again allowed to tour the site, but the electrified fence and armed police create an ambiance which may not be reassuring.
Then there are the two radioactive particles, tiny but potentially deadly, from a still unknown source turning up on the nearby Sandside beach in the past two months - and there is a prosecution still pending because three workers inhaled plutonium from an unknown source three years ago.
But the thorniest problem is whether reprocessing restarts at the site to deal with the remaining 25 tonnes of spent fuel from Dounreay's own fast reactors - accumulated before the decision was made to decommission.
The environment lobby is vehemently opposed to a resumption of reprocessing, and argues that it is cheaper and better to leave the plutonium mixed with spent fuel and store it. Separating it would create another nuclear proliferation problem with unwanted but ready-made nuclear bomb material which then has to be guarded against terrorist attack.
Mr Walsh has softened the UK Atomic Energy Authority line on whether the plant - at £3.9bn the most expensive site to decommission - should restart. "We are evaluating the safest, cheapest, and most effective solution, safety and practicality being most important issues," he said. Reports have yet to be completed and would be made public.
As an engineer Mr Walsh is much more interested in the uranium fuel rods jammed in a sea of liquid sodium in the original Dounreay fast reactor. They went banana shaped unexpectedly when bombarded with neutrons and have been stuck since 1977 when the reactor was shut down. When Mrs Thatcher abandoned the fast breeder reactor programme, and again when the reprocessing plant was condemned to closure in 1989, workforce morale hit rock bottom.
Billy Husband's job disappeared when Dounreay's second fast breeder reactor, known as the prototype, closed and the fuel was removed.
When nuclear regulators said the Dounreay site had lost too much expertise, Mr Husband was rehired. He earns £30,000 and is working on the plant being specially built to dispose of the 1,500 tonnes of contaminated sodium still in the prototype fast reactor plant.
£20m disposal plant
One of the younger workforce, Sohail Ashraf, aged 25, is working with him on a £20m plant being built inside the old reactor building to dispose of the liquid sodium still being kept warm inside. It has taken four years to build and will run for only two years at a cost of £4.5m a year.
It will dispose of 2.5 tonnes of sodium a day in a continuous controlled reaction with water. It will turn the sodium into sodium chloride - salt - which will be returned to the sea when its radioactive caesium has been removed. There are only two grammes of caesium in the sodium, and the plant to remove it cost £1m.
One problem that Dounreay cannot solve is what to do with all its waste. It has a state of the art compaction plant for reducing every 100 drums of existing low level nuclear waste into 20, and is to build intermediate level waste stores for the more dangerous wastes. Lack of long-term disposal facilities or a national repository means a lot of money is being spent on concrete to create storage while a political decision is being made on what to do in the long term.
But the Dounreay golf ball may remain. Scottish Heritage is applying to turn it into a Grade 1 listed building so it can be kept as a tribute to a failed experiment.
Guardian Unlimited © Guardian Newspapers Limited 1999