H2 is pretty dangerous. It is small enough to pass through the tiniest openings and it burns with an invisible flame. However it is pretty common for H2 to be heated and/or cooled with heat exchangers. But you need to use common sense precautions

First of all, do you know why hydrogen is used to cool generators? Because it has the highest specific heat of any substance and also a low electrical conductivity. I've been around, on, and even inside many large generators—more than one while it was running [Yeah, the generators at a nuclear plant are that big.]. Recently at a large coal plant, I noticed a group of men taking a smoke break beside a row of hydrogen tanks used to replenish the generator cooling system. I tried to explain their poor choice of locations to smoke but they weren't interested. Are you familiar with generator curves (efficiency, losses, capacity, reactance)? What aspect of generators are you hoping to study? Are you familiar with the major manufacturers? Have you asked any of them for information?

Another possible source of information, may be to correspond with the companies that produce liquid Hydrogen. They may have Physicists or Engineers on staff with insights on the use of Hydrogen cooling for generators.