The turbine hall at the shut down Bradwell nuclear power plant in Essex, UK, is being demolished as part of the plant's decommissioning. The hall is the largest single building on the site. Meanwhile, an innovative process is being used to clean the site's used fuel pool.
The Bradwell site hosts two 125 MWe Magnox gas-cooled reactors, which operated between 1962 and 2002.
The turbine hall - about the size of a football pitch and some 15 metres tall - was originally constructed in the 1950s and used to house the plant's nine turbine generators.
|Walls come tumbling down ... Bradwell's turbine hall is demolished (Image: Magnox)
Work has already been carried out to strip off the metal sheeting covering the building to reveal its main structure. Ancillary buildings on the Bradwell site - including the auxiliary turbine hall, the main control room, the water treatment plant and the battery room - have already been demolished.
Over 100 tonnes of dangerous asbestos has been removed from the hall, while more than 6000 tonnes of metal has been removed and sent for recycling.
With over 100,000 man-hours of work having already been conducted by Magnox Ltd and its contractor Erith, the next stage is to demolish the main structure, which is expected to be completed by mid-September. The entire project is set to be completed in November.
Magnox Ltd, which manages the site on behalf of the UK's Nuclear Decommissioning Authority (NDA), said that demolition "marks a significant milestone towards reaching care and maintenance on the site, which will see it placed into passive storage in 2015."
The 'care and maintenance' stage of decommissioning is when the reactor buildings are placed in a passive state, known as Safestore, and are monitored and maintained until the site is completely cleared in about 65 years' time, by which time the residual radioactivity will have decreased significantly.
Brian Burnett, head of the Magnox program at the NDA, said, "Accelerating care and maintenance, whilst challenging, is an important element of delivering improved value for money." He added, "The demolition of the turbine hall at Bradwell is a significant decommissioning milestone."
Freeze and thaw
Meanwhile, the Bradwell site has become the first in the UK to use a 'freeze dredging' process, developed in conjunction with FriGeo of Sweden, to remove sludge from the site's used fuel storage pool. The process works by freezing small amounts of waste whilst the equipment is submerged in the pond water. The frozen mass is then thawed to separate out the sludge and debris. The process of thawing and dewatering reduces the moisture content of the contaminated materials, thereby minimizing waste volumes.
The system allows the team operating the machinery to work remotely from the pool area, with the help of cameras and hoists, resulting in a much lower radiological hazard working environment.
Magnox said that the first drum of captured waste had successfully been filled in late July. Up to a further 60 drums are expected to be filled by the end of October.
The FriGeo method of freeze dredging has previously been used to remove oil-polluted sludge from the bottom of bodies of water.
Researched and written
by World Nuclear News