New Scientist can reveal that the nuclear waste agency, Nirex, identified five sites in Scotland and seven in England as geologically suitable for a deep underground repository. The UK government was forced to reverse its prolonged refusal to publish the list by requests in January from New Scientist and others under the new Freedom of Information Act.

Although the list was drawn up in the late 1980s, some of the sites are likely to become candidates for waste disposal again in the future. For this reason, the release of the list is likely to reignite the ferocious debate over nuclear waste disposal.

"The geology in the UK has not changed," says Nirex. "So sites that were considered to be potentially suitable previously on geological grounds could be considered suitable in a future site-selection process."

Hot and high-level

Geologists agree that another attempt to find waste sites would be likely to end up with a similar list. "There will be overlaps," says Dave Holmes, director of environment and hazards at the British Geological Survey in Keyworth, Nottingham. "But it is unlikely that a new site-selection exercise would produce exactly the same shortlist of sites."

Nirex says that any new site-selection process would not begin with the old list, and points out that scientists' understanding of geology is now different.

The waste to be disposed of now also includes hot, high-level waste, which could require different rock properties. And new concerns about sea level rises in response to climate change could rule out some coastal sites.

"But what has not changed,” says Chris Murray, Nirex's managing director, “is that the waste still exists and needs to be dealt with in a safe, environmentally sound and publicly acceptable way for the long-term. Responsibility lies with this generation to ensure this is done."

Weapons waste

More than 50 years ago, the UK was one of the first countries in the world to develop nuclear fission technology into bombs and power sources. But it is now one of the last to work out what to do with the large amounts of waste created, and has fallen behind other European countries and the US.

The US government already operates the Waste Isolation Pilot Plant (WIPP) for weapons waste in a salt formation 655 metres under the Chihuahuan Desert near Carlsbad in New Mexico. It has also chosen Yucca Mountain in the Nevada desert as a potential repository for irradiated fuel from reactors.

Deep underground repositories are also under active investigation at sites in Finland, Switzerland, Sweden, Belgium and France. The consensus of scientists internationally is that burial in stable geological formations below 300 metres is likely to be the safest method of disposal in the long term.

Tiny islands

This is the option that has always been favoured by Nirex, but it has not yet been adopted by the UK government. Ministers are awaiting advice in a year's time from the Committee on Radioactive Waste Management on whether waste should be stored at the surface or buried.

The plan then is to work out how to select suitable locations. But that process has now been rudely interrupted by the release of the site shortlist.

The list of sites (in full below) includes two tiny, uninhabited Scottish islands, military land, areas by nuclear power stations and even sites under the sea.

One of the sites, near the Sellafield nuclear plant in Cumbria, was eventually chosen by Nirex, but it was rejected by the government in 1997 after a public inquiry suggested Nirex's case was scientifically flawed.

Sites shortlisted by Nirex as potential nuclear waste dumps in the late 1980s:

Adjacent to Bradwell nuclear power station in Essex

Ministry of Defence land on Potton Island, 8 km from Southend on Sea. Essex

Under the North Sea, accessed from the port at Redcar, Yorkshire

Under the sea between the Inner Hebrides and Northern Ireland, accessed from the port at Hunterston in North Ayrshire

Killingholme, South Humberside

Ministry of Defence training area, Stanford, Norfolk

Adjacent to Dounreay nuclear plant in Caithness

Two sites near the Sellafield nuclear plant in Cumbria

Altnabreac in Caithness 18 km south of Dounreay

Fuday, small, uninhabited island north of Barra in the Western Isles

Sandray, small, uninhabited island south of Barra in the Western Isles