First let me have a kick at it, to see whether you can understand it. Then I'll ask Tom, who's the nuclear guy, and he can probably give us a more technical answer.
I want to stress that this is a small reactor; it's 10 megawatts. I've been advised that this is part of the problem. AECL built a research reactor in Korea, which is not the same, and it's 30 megawatts, three times the size. Part of the problem, they believe, is the size of the reactor. This has never been built before. That's why this project was so high-risk.
When it's operating, the reactor core cannot have a positive power coefficient; it's designed to have a negative power coefficient. I will say that they have engaged nuclear experts not just from AECL but from around the world to look at all the technical questions and all the modelling. In the modelling, it actually should have a negative power coefficient, but in reality it's the opposite. Nobody has been able to determine or ascertain why that is. That is the challenge.
I don't know whether Tom can add to that.