The European Commission yesterday ordered the British government to bring the storage of nuclear waste at Sellafield into compliance with Euratom treaty rules, under threat of penalties.
The Minister for the Environment, Mr Cullen, welcomed the commission's decision as a "hugely significant development" that vindicated the Irish Government's "robust approach".
The European Commissioner for Energy, Ms Loyola de Palacio, said that British Nuclear Fuel, which manages the Sellafield plant, had failed to comply with the rules on accounting for nuclear material and giving Commission inspectors access to nuclear material.
One of the Sellafield storage sites, a pond containing spent Magnox fuel, was in such poor condition, with high levels of radiation and low visibility, that inspectors could not determine the quantity of spent fuel it held, the Commission concluded.
Ordering the British government to submit a plan of remedial action by the beginning of June, Ms de Palacio said: "This problem has been known for a long time, but no concrete initiative has been taken by the operator to rectify it. The situation had therefore become untenable for the Commission. It calls into question the credibility of our safeguards."
A spokesman for the UK government expressed surprise that the Commission had brought action under Article 82 of the Euratom Treaty, the rules on safeguards. It was hardly likely that the UK would be supplying the material to rogue states or terrorists, he pointed out.
"Yes, there is a problem. We know that. We are trying to deal with it. But there is no suggestion that there is any leakage or any immediate danger."
"We are not going to allow ourselves to be rushed into a plan that could cause problems. Safety and environmental concerns will be at the top of our list," he said.
The spokesman pointed out that the Commission was familiar with the problem since it had been inspecting the site regularly and writing reports about it for the last 15 years.
Mr Cullen said his concern had been to press the UK government over access to information about Sellafield. That, he said, had been the central approach of Ireland's two legal challenges to the UN Court of Arbitration.
The recourse to international arbitration has in turn provoked a legal action by the European Commission, which has brought a case against Ireland at the European Court of Justice. The Commission argued that the Government was wrong to go outside the provisions of the Euratom Treaty.
EU sources in Brussels suggested that the Commission was embarrassed at having to take Ireland, the complainant, to court and so was provoked into stepping up its action against the UK.