The operator of nuclear power station Torness has been reprimanded after it broke rules concerning the disposal of waste, it has emerged.

But EDF Energy, which operates the plant - near Dunbar - has played down safety fears after 28 oil drums containing 26 litres of radioactive residue were wrongly sent to a waste plant in Cumbria, claiming each was no more radioactive than a packet of Brazil nuts.

The drums were sent to the waste plant in August last year and the mistake was only discovered in April. They have since been returned to Torness, where EDF is making arrangements for their disposal.

At a board meeting last month, environmental protection group SEPA reprimanded EDF Energy for the mistake, saying it was not authorised to dispose of the material at a low-level waste repository.

However, SEPA noted that "the incident did not result in any significant harm to the environment" and added: "EDF carried out an internal investigation into the incident and have put in place procedures to prevent recurrence of such an incident." A statement from EDF Energy said: "Although, as the report by SEPA makes clear, there was no actual environmental impact, we treat any potential issue very seriously.

"Our open reporting culture is evident in the way we have communicated with our regulator, even on events such as this, where the radiological impact of drinking a litre of this oil would be equivalent to consuming a bag of Brazil nuts.

"A small number of the oil drums had not been checked sufficiently so as to identify a small volume of oil sludge at the bottom. We have examined our waste consignment practices and put in place additional checks to avoid similar issues arising in the future.

"We returned the oil residue to Torness where it is currently stored awaiting disposal through the wel- established and approved processes used throughout our industry for disposing of this sort of waste.

"EDF Energy takes its responsibilities for safe and clean operation of our facilities very seriously and strives through open reporting practices to continue to engender the trust of the nation."