Dungeness A power station is to be decommissioned once it stops generating electricity at the end of 2006.
The decision by the Nuclear Installations Inspectorate follows consultation over the environmental impact of decommissioning.
The British Nuclear Group said the vast majority of radioactive material will be removed from the site by 2009.
Nick Gore, site manager, said: "We've worked hard to make the application for decommissioning a transparent process."
He added that the station will have provided electricity for 40 years by December.
The first stage of decommissioning involves removing the fuel from the two reactors and taking it to Sellafield for reprocessing.
All plants and buildings except for the reactor containment will be removed by 2021, with final site clearance scheduled for 2111.
The decision to decommission Dungeness A was announced in 2005. The cost of the process was estimated at around £1.2bn.