Magnox decommissioning manoeuvres

18 March 2013

The process to remove fuel from the reactor of unit 1 at the shut down Oldbury nuclear power plant has started. Meanwhile, Berkeley's last two massive boilers have been removed from the site for recycling in Sweden.

Just over a year since electricity generation ended at the Oldbury 1 Magnox reactor, the operation to remove all the used fuel from unit has started. The defuelling process is expected to take 4-5 years to complete.

Oldbury fuelling machine (Magnox) - 200
Oldbury's fuel handling machine (Image: Magnox)

Defuelling of Oldbury unit 2, which shut down in June 2011, began last year and is already 16% complete.

Magnox Ltd, which manages the site on behalf of the Nuclear Decommissioning Authority (NDA), said: "Since Oldbury ended electricity generation, preparations have been underway to prepare the reactor for the defuelling phase of its lifecycle, including removal of hazardous operational gases and chemicals, modifications to the equipment, staff training and reorganization."

Fuel removed from the reactors are stored in the site's cooling ponds and then transferred by rail to Sellafield in heavily shielded flasks for reprocessing.

Defuelling both reactors and sending it to Sellafield will remove over 99% of the radiation hazard from the Oldbury site.

Oldbury site director Mike Heaton commented, "There are over 25,000 elements in the reactor, so this is a major step forward towards decommissioning the site, but there is a long way to go."

After most of the structures at Oldbury have been removed, the site will enter the 'care and maintenance' stage of decommissioning around 2027, allowing the remaining radioactivity to decay naturally. Final site clearance activities are scheduled between 2092 and 2101.

Built in the 1960s and among the first generation of UK reactors, both of the Magnox reactors at Oldbury were originally scheduled to shut down at the end of 2008. However, the NDA requested permission from the regulator to operate beyond that date, earning revenue to help pay for decommissioning.

Berkeley boilers

The last two of 15 boilers, or heat exchangers, have been transported from the site of the Berkeley nuclear power plant and begun their journey to Sweden for recycling.

Berkeley - final boilers (Magnox) 460
The last two boilers leave the Berkeley site (Image: Magnox)

The heat exchangers will be transported by road and sea to Studsvik's site at Nyköping in Sweden, where the company has specialised facilities for volume reduction, decontamination and recycling of heat exchangers and other large components.

Berkeley's two Magnox units were shut down in the late 1980s. The plant's 15 boilers - each over 20m long and weighing more than 300 tonnes - have been stored on their sides outside the reactor buildings since the 1990s.

The first five boilers were removed from Berkeley in March 2012 and have now been smelted, recycling up to 95% of the metal for reuse. A further eight boilers were transported in pairs throughout the past two months.

The completion of the project to move the boilers has removed some 4665 tonnes of low-level waste from the Berkeley site.

Site director Steve McNally said, "The early removal of the boilers is a great achievement for the site. It's not only a huge visual change but also takes the site a step closer to care and maintenance; which is our goal. It also means we have dealt with the waste now, rather than leaving it for the next generation."

Researched and written
by World Nuclear News