The start of the defuelling phase at Dungeness B "will have no bearing on Britain’s energy supplies", the government says.
But the energy firm says detailed analysis has "further highlighted additional station-specific risks", and as such it has taken the tough decision to defuel seven years earlier than expected.
Hundreds of jobs are secure for now, with EDF saying the process will take years, if not decades, and specially trained staff will need to remain on site.
And today, a spokesman for the Department for Business, Energy & Industrial Strategy said the closure will have no impact on energy supplies.
The spokesman said: "The decision to close Dungeness B after 35 years of service is a matter for EDF.
"This has been planned for and will have no bearing on Britain’s energy supplies.
“The Government is committed to the future of nuclear energy, and is looking to reach a final investment decision on at least one nuclear power station by the end of this Parliament, alongside harnessing new nuclear technology."
Construction began at Dungeness B in 1967.
It was to be the first of a new wave of UK nuclear power stations and has a design not copied anywhere else in the UK fleet.
The plant connected to the electricity grid in 1983.
The original design life was 2008 and this was extended following investment in the plant at that time and subsequently.
EDF took over in 2009 and an extended decommissioning date was set for 2028.
More than 700 people currently work at the station.
Station manager John Benn said the defuelling stage involves removing fuel from the two reactors. This process has taken place many times before, but it is usually replaced with more fuel.
This time it will not be replaced.
It could take 10 years before the station is declared fuel free.
It will then move to the decommissioning stage, and then the deconstruction stage.
Mr Benn said EDF currently has no future plans for the site.
But others are still hopeful a 'Dungeness C' could be on the cards.
District councillor, Clive Goddard said: "I know we got an extra 10 years as the original life span was 2008, but it is sad to hear about the station's future. Hopefully jobs will be secure for many years.
"I have campaigned for many years and would like to see a Dungeness “C” as the space and infrastructure is in place and I will continue to campaign and lobby the government for this."
County and district councillor, Tony Hills added: "The station will take years to de-fuel and I hope we can campaign for a 'Station C' as we have a massive investment from UK Power Networks (Transformer building and pylons).
"Also, I would like to investigate a 'green' solution to make use of the big investment by UK Power Networks.
"We are where we are...what comes next is so important for the Marsh."
Neighbouring Dungeness A was decommissioned in 2006.