British Nuclear Fuels is facing further difficulties in the wake of the serious accident at Tokaimura in Japan last week.
The British company, already under pressure following the discovery last month that employees at its Sellafield fuel fabrication plant in Cumbria had been falsifying quality assurance records, faces the loss of Japanese business and tighter scrutiny over the safety of its own operations.
After the Tokaimura incident – which subjected three workers to lethal levels of radiation and forced 300,000 nearby residents to stay indoors for 48 hours – the Nuclear Installations Inspectorate asked BNFL to suspend operations with highly enriched uranium (more than 5% fissionable U-235) at Sellafield.
While a BNFL spokesman insisted that the company’s dry method of fabrication was `miles apart’ from the wet method in use at Tokaimura, he said the company is reviewing procedures and controls at Sellafield `as a prudent measure’. There has never been a criticality accident at Sellafield, he added.
The company said contracts with Japanese utilities for the reprocessing of spent fuel and the supply of plutonium-containing mixed-oxided (Mox) fuel were secure. It added that it was `too early to be precise’ about the impact on future business, but the inevitable backlash against the nuclear industry in Japan seems certain to hit BNFL’s future operations.
John Large, an independent nuclear consultant who has visited Tokaimura, said the plant produced various grades of fuel and the most likely cause of the accident was that the operators had mixed the wrong grade of enriched uranium with acid in the dissolver. Uranium enriched to 2-3% would require a 30kg mass to go critical, whereas 20%- enriched uranium would need only 6kg.
Large said the concern was that the plant’s system of physical and management safety controls had failed to prevent this happening. He added that while the wet process at Tokaimura `carries a higher risk’ than the gaseous method used in the UK, the NII was likely to subject the systems used at the Sellafield site to intense scrutiny.