UKAEA said the cost of decommissioning defunct reactors could fall by £1.5bn if they are taken out of mothballs and demolished before radioactive material is safe for human handling.
The authority claimed it could cut decommissioning costs across its five nuclear reactor sites from £6.3bn to £4.8bn, in a strategy document submitted to the Department of Trade and Industry.
It will do this by bringing forward the date for completion of the clean up operation by 35 years, pushing ahead with dismantling facilities earmarked for 'safe storage'.
Safe storage involves putting off demolition for up to 85 years so radioactivity can decay to less dangerous levels.
This would enable reactors to be dismantled with conventional demolition techniques reliant on personnel entering the most hazardous zones.
But a UKAEA spokesman said robotic tools can now be used in highly radioactive environments. He said pilot decommissioning projects at Windscale advanced gas reactor in Cumbria, and at Harwell's Dido and Pluto reactors, had shown this is possible.