Safety limits on the storage of some of the world’s most dangerous nuclear wastes at Sellafield in Cumbria have been relaxed after an accident knocked out a treatment plant and caused “gross contamination”.
The government’s safety watchdog, the Office for Nuclear Regulation (ONR), has permitted the private company that runs Sellafield to breach legal restrictions on the amount of hot, high-level radioactive waste that can be kept in tanks. The limits are likely to be exceeded by up to 350 tonnes between April 2014 and July 2016.
Critics accused ONR of breaking their promises and putting Sellafield’s profits before safety. But ONR insisted there was “minimal hazard increase”, while Sellafield said it put safety first.
The waste storage limits, imposed in 2001, were meant to reduce stocks to below 5,500 tonnes of uranium equivalent by July 2015. The aim was to minimise the risk of a disaster spreading a plume of potentially lethal radioactive contamination over the UK and Ireland – officially regarded as Sellafield’s “worst credible accident”.
The liquid waste comes from Britain’s nuclear power stations and generates significant amounts of heat. It has to be constantly cooled and stirred to prevent it from overheating.
Sellafield asked for permission to breach the storage limits to help cope with a backlog caused by an accident in November 2013. A plant meant to solidify the waste to make it safer lost power, suffered "gross contamination” and had to be closed for 11 months.
The alternative to exceeding the storage limits was to temporarily close a nuclear fuel reprocessing plant at Sellafield that separates out the waste. But this would mean operating the plant for two or three years beyond 2018, when it is due to shut for good, placing extra strain on ageing downstream facilities, ONR said.
In a redacted report posted online, ONR accepted that breaching the waste storage limits for 16 months would lead to a “modest increase in hazard”. But it concluded that temporarily shutting the reprocessing plant would be more risky, and so has replaced the limits with a weaker “operating rule” administered by Sellafield.
Gordon Thompson, executive director of the US Institute for Resource and Security Studies and an expert on Sellafield, pointed out that the site’s liquid high-level wastes were “one of the world's major concentrations of radiological hazard”. He accused ONR of breaking a promise made in 2001 to halt reprocessing if necessary to ensure that waste stocks were reduced.
Reprocessing fuel from Britain’s newer reactors was “unnecessary, uneconomic, and hazardous,” he argued. “It compounds the waste problem, threatens international security, and never should have begun.”
Martin Forward, from the local anti-nuclear group, Cumbrians Opposed to a Radioactive Environment (CORE), attacked ONR for “its apparent willingness to put Sellafield’s business interests before those of health and safety”. Public confidence in the regulator’s competence would “sink to an all-time low”, he claimed.
Trusting Sellafield to comply with the new operating rule to control waste stocks was like asking a fox to guard chickens, he said. “ONR’s tight regulation of a highly hazardous nuclear industry seems to have gone out of the window.”
ONR stressed that reducing risks at Sellafield was its “number one regulatory priority”. Over the last 14 years it had made “substantial progress” in decreasing high-level waste stocks, it said.
“Allowing Sellafield to operate with highly active liquor (HAL) stocks slightly above the level previously specified will result in minimal hazard increase and a negligible increase in risk,” said ONR’s Sellafield director, Andy Lindley.
“Our position on HAL stocks is fully justified in maintaining a focus on hazard and risk reduction across the site. Replacing the specification with the new operating rule provides adequate regulatory control and the date for bulk HAL removal remains unchanged.”
Sellafield, run by a company involving three multinationals, Amec, Areva and URS, strongly denied that it put business before safety. “The safety and security of the Sellafield site is our number one priority and we never compromise on that commitment,” said a company spokesman.
“We would point out that there has been a three-fold reduction in HAL stocks since the introduction of the specification in 2001. Furthermore, the operating rule will ensure continued year on year hazard reduction.”