Water find raises hopes for nuclear waste site: Industry believes ancient rain shows repository will be safe. Tom Wilkie reports

RAINWATER that fell on the Lake District more than 30,000 years ago has been discovered 850 metres beneath the Sellafield reprocessing plant in West Cumbria. The discovery has given the nuclear industry new confidence that it will succeed in building a radioactive waste repository under the site.

UK Nirex, the industry's waste disposal company, now intends to apply in February for permission to build an underground rock laboratory at Sellafield, following the publication yesterday of data about the geology and the movement of underground water.

The company spent nearly pounds 80m last year on research into the geology and hydrogeology of the site. Its expenditure will rise if it gets permission to excavate the laboratory.

According to Dr John Holmes, director of science for Nirex, the fact that the water deep underground at the location of the proposed repository is about 30,000 years old, indicates that the site is relatively stable. The most important safety issue in radioactive waste disposal is the possibility that underground water might leach radioactive chemicals from the waste and flow back to the surface to contaminate drinking water supplies.

The new study, which draws on data from 11 boreholes sunk to study the site, updates results published more than 18 months ago based on only four boreholes. But informed critics who have seen preliminary versions of Nirex's results warn that some of the boreholes revealed cracks in the rock which may communicate directly with the surface, providing groundwater with a quick return path, before radioactivity has died away.

Dr Holmes conceded that 'there is a potential for a component of upward flow' but he maintained that 'very few of the fractures transmit water and the volumes are very low'. The flow is mainly westwards, out to sea, he said.

Nirex's waste repository will cost more than pounds 2.5bn, but will not start operating until 2010 or later. Only intermediate and low-level waste will be consigned to Nirex's repository. Highly radioactive waste, which represents most of the radioactivity from the reprocessing of spent nuclear fuel, will be stored on the surface at Sellafield for at least another 90 years - and probably into the 22nd century.

Low-level waste includes slightly contaminated protective clothing; while intermediate level waste involves water filters and discarded pieces of cladding from nuclear fuel rods.

The Government has postponed for the third time an announcement about the fate of the new Thermal Oxide Reprocessing Plant (Thorp) which is awaiting permission to start at Sellafield.

The European Commission yesterday acknowledged that it is 'examining as a matter of priority' a formal complaint against Thorp lodged last month by Friends of the Earth.

FoE yesterday said that it would take the commission to the European Court if it did not intervene, an action which would parallel the already declared intention of Greenpeace to seek judicial review, in the British courts, of any decision in favour of Thorp.

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