It's likely going to create steam, just like a reactor today. It is a very effective way to turn a turbine for a generator, after all. All the bits that actually start and maintain the reaction need fuck tons of electricity, so the reaction can literally power itself when attached to a generator.

While there are a ton of formulas for converting energy from heat, to steam, to mechanical energy and then into electricity, it's all basically the same: more power out than you put in is a good reaction.

Almost forgot, water is dual function. It cools the equipment and it acts as an energy transport. I believe ammonia is more efficient in some circumstances, but water is better for obvious reasons.