THE destruction of almost 170,000 litres of radioactive fluid at Dounreay is likely to be completed within the next three months, its operators have said.

The work is seen as one of the greatest priorities in the clean-up of the UK nuclear industry and staff have worked in shifts around the clock during the Christmas and New Year period to keep on track the destruction of liquid metal from Britain's experimental fast breeder reactor, which was housed in Dounreay's landmark dome.

It follows a hiccup when the work was suspended for a week in October, after a pinhole in a stainless steel pipe allowed a litre of the radioactive fluid to escape.

More than 161,000 litres of sodium and potassium, which was used as coolant in the defunct reactor, have been destroyed so far and the site is on course to complete the destruction of the estimated 6300 litres still remaining by the end of March.

The toxic metal is lifted in batches from inside the reactor and its six miles of cooling pipes. According to Dounreay it is then processed through a purpose-built chemical plant to neutralise the alkalinity and extract the caesium contamination, leaving a salty water that can be discharged safely to sea.

Its rate of destruction means the major radiological and chemical hazard inside the reactor is reducing at a rate of 20 million bequerels (units of radio-activity) a second.

Andy Swan, the engineer in charge of the reactor decommissioning programme in Dounreay Site Restoration Ltd which is conducting the £2.6 billion decommissioning of the Caithness plant, said: "We're on course to destroy the remaining six tonnes by the end of March and deliver a major clean-up milestone for the Nuclear Decommissioning Authority."

Dounreay was constructed in the 1950s as an experimental nuclear power complex, but the third and final reactor shut down in 1994.