(December 21, 2001) BNFL's Director of Operations at Sellafield warned the Local Liaison Committee (see box) at its 6 December meeting that "unresolved problems" with Calder Hall nuclear power plant could see the closure of the plant's four Magnox reactors by the end of the year. Brian Watson told members that as a result of the discovery of a loose "charge pan" on one reactor (subsequently identified as located at Chapelcross in Scotland - a sister station to Calder Hall) the company was now required by the Nuclear Installations Inspectorate (NII) to provide a safety case for all the reactors before any refueling could take place.
(560.5352) CORE - Following an accident at Chapelcross in July this year (see also WISE News Communique 552.5297: "UK: Chapelcross shut down after fuel rod accident") when 24 spent fuel rods were dropped 83 feet (25 meters) into a discharge well during defueling operations, two reactors were shut down and further investigations revealed the misaligned charge pan.
Subsequently two of the four Calder Hall reactors, similar in design to those at Chapelcross but part of the Sellafield complex, were shut down to allow defueling related tests to be carried out at Calder Hall. The remaining two Calder reactors have now also been shut down.
BNFL claims the total shutdown of Calder Hall to be a purely temporary measure to allow inspections of all reactors to be carried out. However, it is understood that similar charge pan problems may already have been identified at two of the Sellafield reactors, and other industry observers consider the situation to be extremely serious, with one describing the position as 'potentially terminal' for the nuclear power plant.
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BNFL has described the charge pans as heavy steel guide plates, which form a grid directly on top of the reactor's graphite core. Their correct alignment allows new fuel to be introduced via the fuel charge machine into the reactor. Any misalignment would prevent not only safe refueling or defueling but also the proper operation of the reactors' control rods. Whilst the company was unable to say whether the required safety case for Calder Hall had yet been submitted to the NII, it confirmed that no permission to refuel the reactors had been given by the Inspectorate.
The 300 workers that are employed at Calder Hall will continue to be employed on various reactor jobs. The closure of the plant has been described as "indefinite" and is estimated to cost BNFL around GBP30,000 (US$42,900) per day for each reactor (presumably for lost income from electricity sales etc.), that's around GBP3.6million (US$5.15 million) per month for the four reactors. The fear of workers now is that if the costs and risk assessment of getting the reactors back into operation is too high, BNFL could decide to cut its losses and not re-open the plant.
It is the first time for many years that all four Calder Hall reactors have been simultaneously closed down. The first reactor was opened in 1956 and the fourth reactor came into operation in 1959. In 1996 the power station was granted a ten-year operating extension by the NII following a Periodic Safety Review. BNFL's 2000/2001 Annual Report shows Calder Hall officially scheduled for closure between 2006-2008. Steam and power for Sellafield will now be provided by the site's Combined Heat and Power Plant, which was opened in the mid-90's and is fuelled by natural gas.
Reactor 3 at Chapelcross is still closed down as a result of the July defueling accident.
Sources:
- CORE Briefing, 13 December 2001
- email from CORE, 13 December 2001
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