Providing novel solutions
Barry Snelson on how British Nuclear Group • British Nuclear Groupintethgent.leorde..
set about decommissioning
Nuclear decommissioning is under the spotlight because of the formation of the Nuclear Decommissioning Authority (NDA), but it is nothing new for British Nuclear Group's management services business at Sellafield.
The company has a proud track record and has used its expertise to ensure safe and innovative clean-up work for more than 20 rears. But the number of projects and the pace of work at Sellafield have increased dramatically in recent years.
Four key examples of this are the Pile Fuel Cladding Silo; an innovative liquid-waste treatment process known as TPP; the Floc Retrieval Plant; and the Magnox Swarf Storage Facility.
The Pile Fuel Cladding Silo was built as a dry store for certain wastes associated with reprocessing fuels from the Windscale Piles. Before these wastes could he transferred to a modern facility, much work had to be done to bring the 1950s silo up to modern standards.
The storage environment has been changed from air to an inert gas, which significantly reduces the potential risk of fire, and a new ventilation system has also substantially improved overall safety. Each ventilation connection had to be meticulously drilled through the roof without dislodging support beams. With this system working, all the compartments have now been completely sealed from the rest of the facility. This project, in one of
the most challenging environments at Sellafield, has just achieved six years without a lost-time accident.
Further progress in reducing the amount of liquid radioactive waste stored on the site was made with the successful development of an advanced effluent-treatment process known as TPP. This has enabled the treatment of liquid wastes that have been stored on the site since the 1980s, while reducing the discharges of technetium-99, a radioactive material, by 90 per cent. This means that vet another waste-storage facility can he decommissioned sooner.
In 2004 the recovery and treatment of waste from some of the earliest processing on the Sellafield site will begin. The Floc Retrieval Plant storage tanks were among the first buildings constructed at Sellafield and were used to store wastes from (-hernial] processes. Over the past few years, these enormous concrete tanks have been strengthened with steel jackets, and a protective building has been constructed next to the tanks and slid into place over them. 'Me recovery and processing of these wastes will begin within the next few months and will bring about another significant reduction in the overall hazard arising from historical operations.
The Magnox Swarf Storage Facility is a series of silo-like compartments where solid waste was stored underwater. As a result of these conditions, much of the waste has formed a sludge which now needs to be transferred to more modern facilities.
A significant amount of engineering work has been completed on this facility in difficult operating conditions, along with the decommissioning and removal of a waste-retrieval module which has been retrieving the newest waste from a number of the compartments for the past six years. The 45-tonne package was safely removed using the building crane to negotiate the operations floor with only centimetres to spare in some areas.
The competent delivery of decommissioning projects, like these at Sellatield, demonstrates the capability of British Nuclear Group to manage this legacy and achieve accelerated clean-up safely and effectively on behalf of the NDA, the government and the general public.
Barry Sue/son is managing director of British Nuclear Group, management services, Sellafield.
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