The biggest problem with fission power is up front capital cost. It takes so long to pay off the mortgage that, by the time a nuclear plant pulls ahead over a f

The biggest problem with fission power is up front capital cost. It takes so long to pay off the mortgage that, by the time a nuclear plant pulls ahead over a fossil fuel plant, whoever decided to build that plant is probably getting ready to retire. We have every reason to believe that a fusion power plant will be even more expensive and slower to construct than a fission one. So, even if you skipped over the additional expensive and slow step of proving that a reactor design works, they still wouldn't be chosen by any energy company that expects to turn a profit.