The company, which was last week fined pounds 250,000 for "blatant violation" of safety rules at its Wylfa nuclear power station, at first officially reported it as an incident "of no safety significance", the Independent on Sunday has learned.
Yet the Government's Chief Nuclear Inspector Dr Sam Harbison told Mold Crown Court that it was potentially the most serious nuclear accident to have happened during his time in office. Independent experts accused the company of trying to mount a "cover-up" and Nuclear Electric now admits that its delay in informing the public was "not good enough." The company initially reported the accident as a mere "anomaly", rating zero on the international scale on nuclear incidents, which would mean that it was "of no safety significance".
It was later re-classified with a rating of 2 as "an incident with no significant environmental impact, but which involves some internal plant failure".
No warning was given at the time of the accident and no announcement was made to the press afterwards. Yesterday's UK Press Gazette reports that it was days before the local press picked up that anything had happened, and nearly a year before technical journals carried a detailed story. Local people say it was five days before they heard anything about the "incident".
John Large, the authoritative independent nuclear expert, said yesterday: "It seems there was a cover-up and that even when news of the accident did come out it was downplayed."
The accident occurred more than two years ago - on 31 July 1993 - but it was not until last week's court case that the full story came out. It happened when a pounds 130 "grab" broke from a crane used to refuel the reactor and crashed down more than 25 feet on to the highly radioactive core.
Dr Harbison told the court that if one more thing had gone wrong the core could have caught fire, leading to a "serious release of radioactive material". But although the reactor should have been shut down immediately to avoid the risk of catastrophe, it was kept running for another nine hours.
Dr Harbison described this as a "blatant failure in safety culture" and suggested that the reactor was kept going for commercial considerations. The court heard that when the operators finally did contact the national grid to discuss shutting the reactor down, laughter and giggles could be heard in Wylfa's emergency control room.
This was the second time Nuclear Electric had been fined over the accident and its aftermath. In March last year it was fined pounds 34,000 after being prosecuted by HM Inspectorate of Pollution for deliberately leaking radioactive sulphur-35 and carbon-14 gasses into the air after the accident.
Nuclear Electric admitted that it has failed to make the accident public quickly enough. It claims that "the message was out and about within 48 hours" but adds: "Of course this is not good enough and we recognise this." It said lessons had been learned and new procedures instituted.Reuse content