The floating plant will have a 70-megawatt reactor

The plant, costing £100m ($200m), is due to be launched in 2010.

Russia's atomic energy ministry (Minatom) announced that the base unit for the plant had been prepared in Severodvinsk, in Russia's Arctic north.

The plant - to be called Akademik Lomonosov - will supply electricity to Sevmash, a shipbuilding firm which produces nuclear-powered submarines.

Export potential

Russia's nuclear energy producer Rosenergoatom is financing 80% of the project and Sevmash the other 20%.

According to Minatom, the plant will have an operational life of 12-15 years and has a high level of radiation security.

A senior engineer involved in the project, Oleg Samoilov, said that "in the worst-case accident, with damage to the radioactive zone, civilian protection measures will not be needed beyond a one-kilometre radius around the plant".

Minatom says such plants could be widely used in energy-poor regions and could also power water purification installations.

There are risks of the unit itself sinking, there are risks in towing the units to where they need to be Charles Digges, Bellona environmental pressure group

Russia hopes that Pacific island states will want to buy the technology. According to Rosenergoatom, more than 12 countries have expressed interest in the project.

Russia plans to build seven floating nuclear plants by 2015.

Environmentalists have been highly critical of the proposals.

Charles Digges, editor of the Norwegian-based Bellona website, told the Associated Press that floating nuclear plants were "absolutely unsafe - inherently so".

"There are risks of the unit itself sinking, there are risks in towing the units to where they need to be," he said.