A power station in Kent could start its defuelling phase seven years early unless a number of "significant and ongoing technical challenges" are overcome.
Dungeness B power station on Romney Marsh has been off-line since September 2018 while a multi-million pound maintenance programme was carried out.
This work was due to be completed last year but that timeline changed to August 2021 following a series of delays.
But now EDF say the ongoing challenges and risks "make the future both difficult and uncertain".
As a result, the energy company is now exploring a range of options - including starting the procedure to shut the station down later this year, seven years ahead of its planned defuelling phase.
Eight hundred people work at the station.
A full decision is expected within the coming months.
A statement from EDF reads: "Dungeness B power station last generated electricity in September 2018 and is currently forecast to return to service in August 2021.
"The station has a number of unique, significant and ongoing technical challenges that continue to make the future both difficult and uncertain.
"Many of these issues can be explained by the fact that Dungeness was designed in the 1960s as a prototype and suffered from very challenging construction and commissioning delays.
"Major investments have been made to repair and upgrade the station over many years, including more than £100million in this current outage.
"A number of significant technical risks still remain.
"The current scheduled decommissioning date is 2028. Given the unique technical challenges noted above, a range of scenarios are being actively explored.
"These include moving directly into the defuelling phase later this year - if return to service cannot be achieved - bringing forward the end of generation date, or continuing until the scheduled date of 2028.
"Any change in closure date will be driven by the technical conditions and ensuring we continue to maintain safety over the entire lifecycle of Dungeness.
"We expect to have the technical information required to make a decision in the next few months, as it is important we bring clarity to the more than 800 people that work at the station, and who support it from other locations, as well as to government and all those with a stake in the station’s future."
MP for the district, Damian Collins, says he hopes the "power station will continue to generate power until 2028".
He added: "But if a decision is taken to commence defuelling this year, then this process could take between five and 10 years, and during this time most of the existing workforce at Dungeness would be retained onsite to manage this process.
"The actual decommissioning of the power station cannot start until after the defuelling has been completed."
Work to construct Dungeness B commenced in 1966, with it starting to generate power in 1983.
Neighbouring Dungeness A was decommissioned in 2006.
Mr Collins has previously campaigned for a new nuclear power to be created at Dungeness - 'Dungeness C'.
He added: "For the longer term I have always supported bringing new nuclear facilities to Dungeness, and in particular the new concept of small modular reactors (SMRs).
"I have recently discussed this with Rolls Royce who are leading this project, and have raised it with the Secretary of State for Business and Energy.
"SMRs could be accommodated on the already decommissioned land at Dungeness.
"It would also make sense for SMRs to be located at existing nuclear sites with grid connections.
"I will do all I can to try and bring this new technology to our area and to secure a long term future for the nuclear industry on Romney Marsh."
Cllr Tony Hills, county and district councillor for the Marsh, would also support the creation of further power plants on Marsh.
He described the power station as "critical" to the area, for its contribution to the economy, jobs and the protection it offers the land in terms of sea defences built to shield the site.
An EDF spokesperson said: "EDF will continue to be a key provider of low carbon electricity to meet future demands, as it builds Hinkley Point C in Somerset, and is also making progress with plans for a new power station at Sizewell on the East Anglian coast.
"EDF recognises the need for even more low carbon electricity capacity in the UK and alongside the large nuclear power stations, modular nuclear reactors may well have a contribution to that. Although we have no current plans to develop SMRs or AMRs, we will be looking at the best possible use for our sites in the future."