The government intends to leave a Europe-wide nuclear co-operation body as part of Brexit.
Ministers said that would happen after the UK leaves the EU in a bill published to trigger Article 50.
The European Atomic Energy Community or Euratom aims to pursue nuclear research and training activities with an emphasis on continually improving safety, security and radiation protection.
The Euratom Programme also aims to develop nuclear skills and competence, enabling Europe to maintain world leadership in nuclear safety and waste management.
The UK Atomic Energy Authority (UKAEA) told ELN the news is “not ideal”, especially with regards to the JET programme, a joint European project which is investigating the potential of fusion power as a “safe, clean and virtually limitless energy source”.
A spokesperson added: “Leaving Euratom has obvious implications for the continued operation of the JET fusion experiment (which is operated at Culham by UKAEA for the European fusion research community) after the end of the existing contract at the end of 2018 and UK participation in ITER [JET’s successor].
“Our UK Government sponsoring department, the Department for Business, Energy and Industrial Strategy, have made it clear that they are very supportive of the UK fusion programme and will be working to find a way to continue to operate JET and remain part of ITER after we have left Euratom. We will be exploring all options to make this possible.”