Environmental groups Friends of the Earth and Greenpeace yesterday accused the British government of "avoiding the reality" that the Mixed Oxide (MOX) fuel plant at Sellafield could not be justified economically.
On the opening day of a judicial review in the High Court of last month's decision by the UK government to approve the manufacture of MOX, the environmentalists said a flawed test was used to justify opening the plant.
Lord Lester QC, appearing for Friends of the Earth and Greenpeace, said the EU's Basic Safety Standards Directive went to "the heart of case".
Article 6 of the directive imposed a duty on member states to ensure all new "classes or types of practice resulting in ionising radiation" were justified in advance by their economic, social or other benefits in relation to the health detriments.
However, Lord Lester said that by disregarding construction costs of £470 million incurred by British Nuclear Fuels Ltd the government had diluted the economic test of justification "into something rubbery and elusive which doesn't amount to an effective test at all."
When it approved the MOX plant, the government had said the site would provide "significant economic benefits" with "a net present value of £216 million".
In his submission, Mr Philip Sayles, for the Environment Secretary and the Health Secretary, said Article 6 of the EU directive was "extremely open-texted" and did not identify which costs had to be taken into account when considering economic benefits.
He argued that when looking at the construction of Article 6 the economic benefit was the "standard concept" for commercial and public investment, where some costs could be put to one side.
Some of the economic benefits to the economy of the MOX plant - such as the £470 million spent on construction and the new jobs created - had not been included in the assessment, Mr Sayles said.
And he argued that a specific balance sheet of costs did not have to be drawn up for a specific site.
Rather, the government only needed to consider a range of costs and social benefits which could also be considered when weighing up the benefits and detriments of approving the operation of the MOX plant.
Mr David Pannick, for BNFL, argued that the expected radioactive discharge to the air from the Mox plant was less than 1 per cent of the total annual aerial radioactive discharge.
Also in attendance at the High Court was Ms Susan McDonald, a barrister with a watching brief for the Irish Government.
The hearing continues today.