Nuclear plant told to halt operation

In an unprecedented move, Scotland's green watchdog yesterday ordered an immediate halt of a radioactive waste processing operation at the Dounreay nuclear plant on safety grounds.

The Scottish Environment Protection Agency (Sepa) said AEA Technology, the formerly state-owned firm running the operation, was not able to accurately monitor levels of radioactivity in gasses and liquids discharged into the sea and air from the new, purpose-built plant in Caithness.

The waste in question is highly-volatile sodium, and it comes from Germany. Molten sodium is used as a coolant inside fast-breeder reactors, but it becomes radioactive as a result.

AEA Technology is contracted to convert several dozen tonnes of the resulting contaminated sodium into a safer, less radioactive form using chemical treatments which turn it into salt and water. This operation produces gasses and liquids with very low levels of radioactivity which are discharged into the sea and air. In issuing a legally binding prohibition notice the environment protection agency, an arm of government, also said it had doubts about the declared levels of radioactivity in the 86 tonnes of imported sodium.

The Dounreay site is shared between the privatised AEA and the state- owned UK Atomic Energy Authority; both used to be part of the same organisation.

A spokesman for AEA Technology said the agency's action arose out of information it had provided to the regulator. ``We were surprised at this reactor to our full and fair disclosure ... we believe we can comply with all of the agency's requirements.''

Sepa also believes the importation of contaminated sodium may not have complied with laws covering waste imports and is considering a prosecution. AEA Technology says the shipments had been cleared by the German authorities, the Scottish Office and HM Industrial Pollution Inspectorate, when the contracts were arranged two years ago.