The Minister for the Environment, Dick Roche, has said the latest information on a recent leak at the THORP facility at Sellafield, is a further damning indictment of the plant's safety record.
Mr Roche was commenting after the UK Authorities passed on the findings of the British Nuclear Group's investigation into the leak.
They found that material had been leaking from a damaged pipe between January and April of this year.
A secondary containment cell prevented any radioactivity reaching the environment.
Mr Roche said that opportunities were missed to correct the problem and the incident had only increased the Government's concerns about the plant.