The electroweak interaction is a unification between the electromagnetic and weak nuclear forces. This unification does not occur until particle interaction energies are in the range of 100 GeV, the so-called unification energy. This energy is generally not available in natural reactions except just after the Big Bang. You can get it in high energy particle accelerators, but not fission or fusion reactions. Uranium or plutonium fission releases total energy in the range of 200 MeV (MeV, not GeV). Common fusion reactions (D-D, or D-T) release energies in the range of 25 MeV per reaction. Nowhere near those needed for electroweak interactions to occur.
I have no fear that any more radionuclides are going to be expelled than there ever were ~ that part of the science is certainly settled, eh! It ain't gonna' blow up, but the fellows running the show (presumably all highly trained physicists and atomic power plant engineers and designers) said the heat increase wasn't explainable.
I think it is explainable using convention heat transfer theory, as I noted previously.
Certainly some of the red-hot radioactive waste with short half-lives has to be doing something.
A poster up the line noted that when the Japanese point to a problem they're probably trying to hide a worse problem. No doubt we will all find out what that is over the next few months.