The High Court in London has heard that the economic justification for Sellafield's new MOX nuclear reprocessing facility is flawed. Greenpeace and Friends of the Earth have taken a legal challenge to try and prevent the start-up of the controversial plant.

Lawyers representing the two groups have been arguing that Sellafield's operators, British Nuclear Fuels, have not justified their new MOX plant, which is now expected to open later this month, on economic grounds. They argue that the company is bound to do so under European Law.

Counsel for the groups told the judge that the bottom line of any economic cost benefit analysis would have to be positive. However, he said that, in the case of MOX, there was no net economic benefit. As of last June, he said, the capital costs of building and setting up the MOX plant were £470m, while consultants had estimated the net value at only £216m.

However, Mr Justice Collins has already warned the environmentalists that, even if they win on this economic point, it will not necessarily mean the end of MOX.

In a separate development, Senator Shane Ross accused the Government of not being serious about Sellafield in the Seanad this morning. He asked that the British Ambassador be invited into the Seanad to answer questions about developments at the reprocessing plant.

Senator Ross also asked whether the Minister for Foreign Affairs could summon the British Ambassador to Iveagh House to issue a formal and public protest about Sellafield.