A leaked internal memorandum to senior staff at Nirex, the state-owned nuclear waste company, indicates that much more data is needed to get an accurate picture of the rock that would surround the radioactive waste.
Cumbria County Council and the environmental campaign group Friends of the Earth called on John Gummer, the Secretary of State for the Environment, to reopen the public inquiry into Nirex's plans for an underground laboratory which the company hopes will prove the site suitable for a pounds 2bn dump.
The site at Longlands Farm, near Gosforth, on the western fringe of the Lake District National Park, is only two miles from British Nuclear Fuel's reprocessing plant where waste is at present stored on the surface.
Despite spending pounds 200m of public money investigating the fractured volcanic rock, modellers said that they needed between 10 and 100 times more data, John Holmes, director for science at the company said in the memorandum. He suggested that without more favourable permeability estimates, Nirex might "struggle to make a case for the site".
Mr Gummer is at present studying the report of a five-month public inquiry into Nirex's plans for the laboratory. He could give his decision at any time, but Cumbria council and FoE believe that the memorandum reinforces the objections made at the inquiry.
"Once again, something has come to light that flies in the face of the contention that everything is going well at the site," council group leaders said. At the inquiry, the council argued that Nirex had chosen Longlands Farm because of its proximity to the reprocessing plant and because it feared local opposition at geologically safer sites elsewhere in Britain.
The damning memorandum was leaked to both the council and FoE. "What it says is that Nirex must either spend hundreds of millions of pounds on more research, cook the books or clear off," Dr Patrick Green, the senior nuclear campaigner at FoE, said.
"They must now accept defeat. If they try to manipulate the data they already have, we will expose them."
Nirex scientists are evidently concerned that without more data they cannot reliably model the flow of water through the rock, which needs to be capable of containing the radioactive waste for 100,000 years. "There is still a gap between modellers and hydrogeologists" on interpreting data on the groundwater pathways, Mr Holmes said.
Nirex, which spent pounds 10m presenting its case at the inquiry, played down the memorandum, describing it as a director challenging his team to continue the search for rigorous answers.
Scientific debate was being turned into a "political stunt" the company said. "If the Sellafield site is not scientifically suitable, Nirex has always said it will walk away."Reuse content