The Conservative party is split over whether the UK should remain in Euratom, the group managing the movement of nuclear material across Europe. The division threatens the UK government’s brexit strategy to leave Euratom at the same time as the EU.

Nine Conservative MPs have indicated they would line up with Labour and the Liberal Democrats to vote against leaving the treaty, making it difficult for Prime Minister May to secure a parliamentary majority.

Side effects of leaving Euratom without a proper plan in place could include nuclear plants forced to shutdown and cancer patients put at risk.

Senior politicians from the Conservatives and Labour have said Euratom is vital to protect the UK’s nuclear interests. Back in February, MPs were warned nuclear power stations would be forced to shut down if new measures were not in place by the time the UK quit Euratom and the EU in 2019:

“Unlike other arrangements, if we don’t get this right, business stops. There will be no trade. If we can’t arrive at safeguards and other principles that allow compliance [with international nuclear standards] to be demonstrated, no nuclear trade will be able to continue.” – Rupert Cowen, a senior nuclear energy lawyer at Prospect Law

Dr Nicola Strickland, president of the Royal College of Radiologists, told the Evening Standard leaving could put cancer patients at risk by threatening the UK’s supply of radioactive isotopes used in cancer scans and treatment.

Dominic Cummings, who ran the official leave campaign during the #brexit referendum, also weighed in on the Euratom debate via Twitter:

Mr Cummings also recently declared leaving the EU may be ‘an error’.

The government is reportedly scrambling to work out what would replace Euratom so as to stop the potential rebellion. One option could be to seek associate membership of Euratom, although it is unclear if this would meet the UK’s needs.

Currently the only country with a form of associate membership is Swtizerland, and even Switzerland is only signed up to Euratom research activities – excluding nine out of the ten Euratom chapters the UK and the rest of the EU are signed up to.

Of course, the easiest way to avoid leaving Euratom would be to remain in the EU.

James Chapman, who served as brexit minister David Davis’s chief of staff until shortly before the last election, recently suggested May’s insistence the European Court of Justice (ECJ) has no UK oversight after brexit is the reason the government wishes to leave Euratom as well:

“Now the government has announced its intention to withdraw from the Euratom treaty as we leave the EU and the reason for that appears to be there’s a locus for the ECJ in that treaty which covers the free movement of nuclear scientists.

“Now I would have thought the UK would like to continue welcoming nuclear scientists who are all probably being paid six figures and are paying lots of tax. But we’re withdrawing from it because of this absolutist position on the European court. I think she could show some flexibility in that area.”

The ECJ is the ultimate enforcer of Euratom’s rules. While all 28 EU member states are Euratom members, the organisation is not technically part of the EU. It is unclear whether leaving the EU really does mean the UK must also leave Euratom or not, or if it’s even legally possible for the UK to u-turn on leaving Euratom.

Euratom is also responsible for the development of ITER, an international nuclear fusion research and engineering megaproject seeking to produce unlimited clean energy. The project is primarily funded by the EU.

Update: the UK government has now admitted no formal review of leaving Euratom was ever carried out, despite the fact it has notified the EU the UK will be leaving Euratom as part of brexit. [12/07/17]