"You have to be ready for somebody to change your mind, you have to be," said Prof Steve Cowley, the director of the Culham effort.
"I don't know in this case. It might be that they have some good ideas, but partly because they are doing it commercially they are not going to tell us, so it can't be subject to the normal scientific peer review.
"If they do have some innovative ideas they'd be fools to tell us."