Energy from nuclear reactors is not cheap at all. Even if you try to ignore the risk of a disaster, nuclear reactors are incredibly expensive to build and decommission and the story of cheap nuclear energy is a pipe dream that was never realized.
Why do you think the nuclear lobby complains about Congress? There is no law on the books against building new nuclear plants. Of course you have to get the permits, but Congress does not give those out, the various government agencies do, and they usually do give out permits. There are already permits issued for several new nuclear plants in the US. No the nuclear lobby complains about Congress because they want money. Because the story about cheap nuclear energy is a lie and the private sector will not build a nuclear reactor without getting a bunch of taxpayer or electricity payer money to fund it.
Take another example natural gas. Nobody asks Congress to build natural gas reactors, they just build them. That's because they actually make money, which means people invest in them, so nobody needs to squeeze money from the taxpayer to make them. But nuclear plants are huge and expensive boondogles and actual investors are not dumb enough to invest in them. So they go after the taxpayer of course hoping that the taxpayer is dumb enough.