An unusual scuffle broke out last summer about what role nuclear energy should play at next week’s United Nations climate summit hosted by the U.K.

The tiff began in August when organizers invited the International Atomic Energy Agency (IAEA) and other industry advocates to set up shop in the meeting’s quieter Blue Zone instead of the public Green Zone, where companies enjoy higher visibility. "Every application on nuclear energy for the Green Zone at the upcoming COP26 conference has been rejected,” London-based lobbyists at the World Nuclear Association complained in a letter to COP President Alok Sharma. "We are deeply concerned.”

The kerfuffle over colors underscores the awkward position nuclear power occupies in discussions about the best way to decarbonize the global economy. Anti-nuclear nations from Austria to New Zealand have opposed attempts to label atomic technology with the same credentials as wind or solar power. The industry is also excluded from multilateral financial aid for clean energy at places such as the World Bank.