Frankly I don't entirely credit the conclusions of any "authority" right now -- everyone outside the plant management loop is making educated guesses, and many of them have powerful institutional biases shaping their thinking.

And if we set aside conclusions, this is the best orientation to the problem that I've seen so far. I'm not worried about his credentials, as this is internally consistent, and externally consistent with what I know of physics. Maybe the plant lacks a third containment, or is using a different fuel, but I can adjust my understanding of the system for those facts as they come along.