Kenny MacIntyre: "The phased run-down will essentially begin after the announcement on Friday"

The Scottish Secretary Donald Dewar and the Energy Minister John Battle revealed details about the operation on Friday morning.

No new nuclear material will accepted for reprocessing at the coastal plant in Caithness, they said.

Existing waste, which includes a consignment from the former Soviet republic of Georgia, will be dealt with - but not until the plant is given the all-clear by safety inspectors.

The announcement will be made by Donald Dewar

From then, the focus will be on winding-down the plant. All efforts will be channelled towards clearing up the nuclear waste in the plant's underground shaft.

Dounreay was built in the 1950s. It has been dogged by a string of controversial incidents, particularly since the start of the year.

Those hoping to see a swift end to the plant will be disappointed as experts predict decommissioning will take a generation.

The plant provides much-needed employment in the area

BBC Scotland's industry correspondent Kenny MacIntyre said the latest announcement was rooted in the swathe of bad publicity surrounding Dounreay.

"Mr Dewar felt the real reason that all this material came into the public domain was because in a sense Dounreay had become more open," he said.

"There was a feeling that if something wasn't done quickly there would be a mass scare in Scotland about the impact of Dounreay.

"They've decided to bring the whole closure process forward."

But although many will cheer the news of Dounreay's demise, there is concern about future employment prospects in the area.