WORK to remove one of the most persistent problems affecting the clean-up of the Dounreay nuclear site has begun beneath the waves off Caithness.
A remotely operated vehicle is combing the seabed to find the worst of the radioactive particles that have caused concern for more than quarter of a century.
Up to £25 million will be spent on covering an area the size of 60 football pitches and
on monitoring up to the 2020s.
The first phase of the operation, which will run until the end of September, is expected to provide information on the effectiveness of the system and help plan further work. Weather conditions will limit the operation to May-September each year.
Simon Middlemass, managing director of Dounreay Site Restoration, the firm contracted to clean up and close Dounreay, said: "The start of seabed clean-up heralds an important phase in the closure programme.
"We've made significant progress in recent years to clean up and dismantle the site itself. Now we are cleaning up off-site, a legacy that has cast a shadow over the site for too long."
But Duncan McLaren, chief executive of Friends of the Earth, said: "This reminds us that the impacts of the nuclear industry were more widespread and expensive to deal with than anticipated. It is a lesson to those with misplaced enthusiasm for a new generation of nuclear facilities.
"It's welcome that the scale of the problem is being recognised and being cleaned up appropriately but it's sad that we have had these particles loose in the environment for a long period. I hope we have learned the lessons for the future."
Particles, or hotspots, are fragments of irradiated nuclear fuel discharged into the sea during the 1960s and 1970s. The most hazardous ones are near an old discharge point on the seabed and their disintegration is believed to contribute to the number of smaller particles found on nearby beaches.
They were discovered in 1983 and since then they have been found on the seabed and on the Dounreay foreshore as well as other sites, including a public beach at nearby Sandside.
The scale of the problem was only realised by the UK Atomic Energy Authority in the late 1990s. Particles were removed from beaches; those on the seabed were only monitored.
Divers were later used to map the area of particles and remove any found before this was considered too dangerous.
Then last year, after a two-year consultation, it was decided to remove the most hazardous offshore particles while continuing to recover those on beaches.
Particle removal is one of the biggest issues facing the site, due to be decommissioned within 25 years at a cost of £2.9 billion.
The independent Dounreay Particles Advisory Group estimates 1,500 hotspots big enough to cause significant damage to health are in the sediment. A further 6,000 smaller, less hazardous particles may also be in the area close to a 2km radius fisheries exclusion zone.
The undersea vehicle carries radiation detection equipment and a suction system that can retrieve particles buried up to 50cm down. It digs out a "cone" and filters out the particles, returning the sand to the seabed.
Last week a report showed nine particles were found on Sandside beach between July and December 2007, bringing to 103 the number of particles found there since 1984. The number found on the Dounreay foreshore is now 252.
Range of options looked at – but doing nothing was not oneDOUNREAY managers decided to recover the particles which pose the greatest risk to health after a two-year research and consultation exercise.
Originally, 24 options were looked at, which were narrowed down to 11 and, finally, one best practicable environmental option.
Among the suggestions ruled out was the possibility of using lasers to break down the particles, and training dolphins to remove them.
It was also considered impractical to remove every particle and too costly to dredge the whole seabed.
Other ideas were to continue monitoring without removal, or to restrict access offshore or to affected beaches.
However, the consultation showed clearly that doing nothing was not an option. It showed that those questioned wanted the particles cleaned up both onshore and offshore, while keeping the cost down.
Consultants Entec took the views of eight groups, including local people, staff and contractors and national bodies.
They also held workshops and exhibitions and issued a questionnaire.
Overall, environmental criteria for tackling the particles were given the highest rating, followed by social and economic issues. Among locals, social and economic issues were seen as more important while safety concerns were least important.
Dredging the seabed, and restricting access to beaches, were not supported.
The full article contains 795 words and appears in The Scotsman newspaper.
