I don't believe he needs to prove it can do anything useful although that would be great. As a scientist he's not necessarily interested in the end product. He's more interested in seeing if there's a new undiscovered nuclear process here. That alone would rewrite the science books and probably win him a Nobel.
Well, that may be true, but I'm just saying that proving it with experiments that are so subtle that you've got to rely on statistical measurements is not going to convince a lot of scientists. If he produces large amounts of usable energy, that's kind of hard to argue against.
On the other hand, there are plenty of bizarro conclusions that scientists have drawn from statistical studies in other contexts. A good example is quantum entanglement. And that is largely accepted by the scientific community, so it might be possible for him to gain acceptance of the theory without producing usable energy if others can duplicate it.