The UK Atomic Energy Authority, which operates the complex, was severely criticised in a safety audit six months ago.

It was given until 30 November to formulate a plan to bring the plant up to scratch after government inspectors found that more than 140 improvements were needed.

The UKAEA's plan was unveiled in Thurso - where most of the 1,600 strong workforce lives - on Monday afternoon.

It was welcomed by the HSE's chief inspector of nuclear installations, Lawrence Williams, as providing "a good basis on which to go forward".

Mr Williams said: "I particularly welcome the intention to reduce the overall decommissioning timescales.

'Vital that priority is given to recruitment'

"Some of the proposed timescales seem rather long, for example, the completion of safety cases. I recognise that the plan must be realistic, but we shall be pressing the UKAEA for improvements on these timescales.

"The Action Plan indicates dates for achievements, with more or less precision depending upon the need for more detailed programming.

"UKAEA indicate they will need to recruit around 70 new engineers and scientists. I believe it is vital that priority is given to the recruitment of these people as the delivery of the Action Plan is dependent upon the availability of suitably qualified staff, particularly in the early stages."

Highly radioactive waste is kept at the plant

Inspectors from the Health and Safety Executive moved onto the site in June after a digger sliced through a power cable, leaving reprocessing facilities without electricity for 16 hours.

Parts of the plant without electricity held some of the most potentially lethal substances known.

There had previously been reports of fires, leakes and explosions at the site - and radioactive particles were found on the seashore near the complex.

The inspectors' report criticised operators for passing on too many tasks to contractors, lacking strategies to deal with radioactive waste, and making little progress on decommissioning.

Managers were also accused of being too secretive.

Conditions ranged from very good to very bad

They were banned from carrying out any non-essential work and reprocessing areas affected by May's power cut have been closed ever since.

Managers now acknowledge that many of the problems resulted from too many experienced engineers and scientists being allowed to retire early on "golden handshakes" following the shutdown of Dounreay's main reactor in 1994.

A UKAEA spokesman said: "The work will be carried out safely, properly and on a realistic timescale - UKAEA will not cut corners to save time."