How Dounreay's nuclear dream turned sour

But more pressing is the persistent threat to the health of local people and workers, who have been exposed to a catalogue of near disasters since work started on the experimental reactor in March 1955.

The plant was seen as a Godsend at a time when the north needed jobs and the dangers of the nuclear age were played down in favour of the potential benefits.

However, in 1984, fears were first raised by locals concerned by their atomic neighbour. It was then that the first granular sand-sized specks of plutonium were found to be leaking out of the plant and on to the beaches of Caithness.

Several hundred particles have been discovered since, with one government report concluding that “fatalities might occur”, and that such hot spots “present a real hazard to health”.

As well as finding particles on private land, many have been identified on Sandside beach, a public site. The discovery of a particle off-shore led to a fishing ban within 2kms of Dounreay in 1997.

The UK Atomic Energy Authority (UKAEA) said it could “probably narrow it [the leak] down” to a waste shaft or an old underwater effluent treatment chamber and that the chances of exposure to the particles was negligible. But if such exposure did occur, it caused skin blistering.

The hot-spots were probably a legacy of the treatment of nuclear fuel in the Sixties and Seventies.

It is believed that 100,000 particles may been discharged in a single incident, probably in 1963, from either the waste shaft or effluent chamber.

Another serious breach occurred in May 1977, when a shaft containing radioactive waste exploded, blowing off a huge concrete lid and blasting scaffolding poles up to 40 metres away.

The explosion was caused by water flooding the shaft and reacting violently with sodium and potassium buried along with the waste.

No-one will ever know for sure the extent of the contamination, but as the controversy raged, pressure from the public led to investigations.

In 1994, a UKAEA study revealed levels of plutonium in the homes of Dounreay workers “significantly” higher than in other homes in Thurso.

Workers at the plant had been carrying home plutonium particles – readings were 50 times higher in 21 out of the 34 homes monitored.

By then, Dounreay had absorbed its second generation of local workers.

Another investigation began in 1997, but two years later, the UKAEA would be accused of “dragging its feet”.

In 1998, the Health and Safety Executive made 143 recommendations on safety, quality, environmental systems and an integrated management system.

Safety has been the most contentious issue surrounding the reactor, with the UKAEA fined 101,000 in 2000 on three charges of contaminating three workers in 1995.

They were also fined on a separate charge after a contractor’s mechanical digger severed a power cable, cutting off the electricity supply in May 1998.

Today’s safety concerns are a far cry from the optimism and faith placed in the all-powerful fast breeder reactors.

The slogan at the time was “atoms for peace”. Hundreds of scientists and engineers moved to the remote northern town of Thurso to be part of a bold and appealing venture aimed at providing limitless amounts of electricity at negligible cost, by using plutonium instead of uranium as a fuel, extracting energy with 60 times more efficiency. The plutonium created by the burning of uranium in ordinary reactors could be used to power the world.

However, the scientists of the Fifties and Sixties did not always take the proper precautions, and 1,000 tonnes of radioactive junk thrown down a shaft dug 65 metres into the cliff-top would later provide the fuel for the 1977 explosion.

But the fast reactor did not work and fell from favour, with the cost of extracting energy from plutonium higher than alternatives.

“The nuclear industry’s holy grail came to a graceless end,” said anti-nuclear campaigners – but, as the latest contamination shows, its radioactive threat shows little sign of dissipating.