Tom Greatrex, chief executive of the Nuclear Industries Association, said: “Nuclear production is the lowest since 1982 because we have fewer nuclear power plants.
“We are down to 5.9 gigawatts of nuclear capacity, the lowest we have since 1975, after Hunterston B and Hinkley Point B enter their long-planned retirement in 2022.
“We have literally known for decades that the current nuclear fleet would be retired in the 2020s, but successive governments have stalled for years on implementing new projects, hoping something will happen.
“That’s why we have to move forward with a new program of projects from Sizewell C onwards, so we won’t be in this situation in the 2030s onwards.”
Eight of the UK’s nine remaining nuclear fleet are operational advanced gas-cooled reactors (AGRs) spread across three main sites, all of which are scheduled to close between 2026 and 2028.
EDF’s Sizewell B station in Suffolk, which opened in 1995, uses a different technology. Its single pressurized water reactor is generating another 1.2 gigawatts, but it too will be shut down for maintenance in October. Its final closure is scheduled for 2035.
An EDF spokesman said: “We will seek to extend the life of Sizewell B by 20 years and will operate the AGRs as long as they are safe and commercially viable but the AGRs will not be able to operate forever.
“That is why we need a clear timeline for UK nuclear development beyond Hinkley Point C and Sizwell C.”
A separate analysis by Carbon Summary confirmed the decline in nuclear production but showed a similar decline in the amount of electricity generated in the UK from fossil fuels.
Over the past few years, the UK has produced around 40% of its electricity from burning gas, but in 2023 this falls to 33.5%, with a further 1% coming from coal.
The government has been contacted for comment.