Decommissioning milestones for UK plants

29 March 2010

Decommissioning work at two of the UK's oldest nuclear power plants has reached major milestones with the final removal of uranium from Chapelcross and the removal of asbestos cladding from Calder Hall. 

 

MDU leaves Chapelcross (NDA)
The last MDU leaves Chapelcross (Image: NDA)

The five-year project to strip 2300 tonnes of asbestos cladding from the heat exchangers, turbine halls and associated plant from Calder Hall which has now been completed was the culmination of over a million man hours of work. In conjunction with a similar project at Chapelcross, the project is thought to be the largest asbestos strip undertaken in Europe.

The Calder Hall Magnox power station generated electricity from 1956 to 2003, but once operations ceased the asbestos was no longer kept at a constant temperature and its stability could not be guaranteed. Removal of the material, which is carcinogenic, therefore had to be in line with strict regulatory controls. Much of the work also had to be carried out at height, using scaffold towers 36 metres tall to provide the structure for tents around the outside of the sixteen heat exchangers, preventing the release of asbestos and providing safe, ventilated working conditions for the workers.

The project, which was originally estimated to cost £27.58 million ($41.39 million), was completed under budget at a final cost of £26.25 million ($39.39 million).

Chapelcross says goodbye to U

Meanwhile, the former Chapelcross nuclear power station saw the final departure of Magnox depleted uranium (MDU) from the site. Over 10,000 drums of the material, produced from the reprocessing of used fuel from the country's Magnox power plants, was stored at the site during the 1970s and 1980s.

MDU is the uranium recovered from the reprocessing of fuel from Magnox reactors, which formed the UK's first civil reactor fleet. The recovered uranium is referred to as 'depleted' because it was not enriched in the first place. Up until the mid 1990s, MDU was used to manufacture fuel for the UK's advanced gas-cooled reactors (AGRs), but this was discontinued for economic reasons. However, in the interim, Magnox fuel has continued to be reprocessed. Although most of the UK's Magnox power stations are now being decommissioned, four units - two each at Wylfa and Oldbury - are still in operation.

The MDU was stored at Chapelcross in "oil"-type drums. These were transferred into modern stainless steel overpacks before transportation to the UK's primary uranics management facility at Capenhurst. The material could still potentially be re-used in the nuclear fuel cycle.


Removal of the last drum signalled the completion ahead of schedule of a five-year £6.5 million ($9.7 million) project. According to the UK's Nuclear Decommissioning Agency (NDA), it also signified the reduction of a major hazard associated with the UK's civil nuclear legacy.

"This may not be as high profile as the demolition of the cooling towers, or removing asbestos from the heat exchangers, but it has been a major project and we're delighted to be able to complete it," said Dave Wilson, Chapelcross site director. 

 

Researched and written

by World Nuclear News

 

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