British Nuclear Fuels has denied that its Thorp reprocessing plant at Sellafield in Cumbria was closed because of a leak of radioactive waste which occurred in a perforated pipe.
The environmental group, Greenpeace, described the incident as a "major leak" and accused the company of trying to keep it secret.
The BNFL plant has been closed since April, but a spokesman for the company said it was a planned engineering "outage" or closure for regular maintenance. It was "fortuitous" that a "perforation in a pipe" was found when maintenance began. The spokesman said the "perforation" was "technically" a leak.
The leak occurred when metal shards from slurry-type waste perforated a corroding "transfer" pipe carrying the intermediate-level radioactive waste.
Environmentalists have accused the company of covering up the leak of radioactive waste. Cumbrians Opposed to a Radioactive Environment (CORE) received an anonymous letter from a worker in the plant, which said pipework had been found to be leaking and it could take months to repair.
BNFL said special in-cell cameras had detected that some "accelerated wear" had occurred in the transfer pipes. The potential for erosion was recognised at the design stage, but "we weren't able to appreciate the exact erosive quality of this waste". BNFL's spokesman said a duplicate set of transfer pipes was built for this reason. He stressed the leak did not go beyond controlled areas and did not go outside the plant.
BNFL dismissed as "absolute rubbish" claims that the leak emerged only because of this letter. The company said it announced the closure in its newsletter in mid-April. Mr Martin Forwood of CORE said, however, that the company stated it was looking at "accelerated wear in the pipes" but there was no mention of a leak or "perforation".
The spokesman said the plant was due to reopen in July. Asked if the leak would delay the reopening, he said, "We don't have any reason to believe it won't open when scheduled."
Mr Forwood said BNFL would have to dig through concrete walls to get into the cells to repair the leak. The company said it anticipated this kind of problem and installed a spare set of pipes to switch over to.
"We are concerned that they will switch to the second set without clearing up the contamination from the leak," Mr Forwood said. "If they repair the leak it would be September before they reopened, which is what the letter says."
He said CORE really wanted to make sure the exact extent of the leak should be known. It feared BNFL would try to get the Nuclear Installations Inspectorate, the industry watchdog, to approve using the duplicate set of transfer pipes without clearing up the contamination. "They must clear that first, no matter how many months the plant is closed for."
Greenpeace said: "The Sellafield plant is in real trouble. BNFL must not be allowed to operate a plant that clearly has inherent design faults, threatening worker safety and the environment."
Recently, British authorities banned the consumption of pigeons found within 10 miles of the plant.
