Environmental groups today lost their High Court bid to challenge Government approval of a controversial nuclear reprocessing plant.
Friends of the Earth and Greenpeace were seeking to block the opening of the mixed plutonium and uranium oxide (MOX) plant at Sellafield in Cumbria.
But Mr Justice Collins, sitting in London, ruled the Government had made "no error of law" in granting approval.
Both groups fear the Sellafield scheme could lead to pollution, and also become a target for terrorists or theft of nuclear materials.
Their lawyers say there is insufficient evidence that the plant would attract customers such as the Japanese to help make it viable.
In court they argued the Government had also taken a "distorted" view when it decided in October that allowing the introduction of MOX was "economically justified" under European Union law.
Under an EU directive, governments are required to ensure that the economic, social and other benefits of new processes which create exposure to ionizing radiation outweigh any detriment to health before they give the goahead.
Lord Lester QC, for the campaigners, said the Government's decision that the MOX plant was "economically justified" was based on distorted figures as £470 million construction costs for the Sellafield plant had been "ignored and disregarded" in assessing its benefits.
If all relevant costs were taken into account the scheme would show an overall financial loss.
Philip Sales, appearing for the Government, disagreed and argued that the exclusion of the £470 million "sunk costs" was a "perfectly rational" decision.
The Government had been assessing the generic benefits of MOX.
Potential benefits of the Sellafield plant for BNFL's businesses were "likely to run into hundreds of millions of pounds" but had also been left out of the balancing exercise.
Agreeing with Mr Sales, the judge ruled: "Justification is clearly not site specific."
He added the generic approach was "probably right" and justification for MOX "was established".
Later BNFL, which runs the Sellafield plant, welcomed the judge's decision that the MOX operation was both lawful and justified.
A statement said: "This is good news for the plant, the workforce and the local community.
"Our customers have been very patient and we now want to get on with the job of manufacturing MOX fuel for them."
Friends of the Earth and Greenpeace were later granted leave to appeal. A provisional date for the appeal has been set for November 27.
Charles Secrett, executive director of Friends of the Earth, said: "Today's judgment allows the Government to ignore plant construction costs when deciding whether a nuclear project is justified.
"In this land of fantasy economics the Government can fiddle the figures until it gets the results it wants."
He added: "Despite this bitter blow the campaign against MOX continues. We owe it to ourselves and future generations to do what we can to stop this nuclear madness from proceeding."
Stephen Tindale, executive director of Greenpeace UK, commented: "While today's decision is disappointing, our fight to stop the MOX plant from opening is not over."
He said the plant "poses a substantial risk as a terrorist target and producer of bomb–making equipment and faces three more legal challenges."
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