You can tell because for profit(if staterun) companies are building them across the world. France is drawing significant profits from existing nuclear, and constructing new. Nuclear has been ridiculously profitable for most countries which built them, with the sole exception of countries which started building them, then forbid nuclear. Many countries in Asia are building them because its cheaper than coal power. Most countries impose nuclear specific taxes, in addition to long term disposal fees, which exceed the price of production by several times. Sheer state profit. Despite this, the main reason nuclear does not get built in Europe is regulation, the the risk of losing the investment due to changing laws on nuclear. Which has happened several times.
Byproducts, aside from nuclear weapons, which most countries do not have, are a negligible part. Sweden for instance built ample nuclear early, but never built the kind of reactor which is used in nuclear weapon production. Sweden also didnt subsidize it, but rather has been taxing it at an additional 300-500% in addition to long term disposal fees(so little of which actually went to long term disposal they introduced a second free named exactly the same 40 years latter). Despite also discarding the cooling water heat into the ocean completely needlessly, all it took for these plants to be profitable was not forcing them to shut down when public opinion turned. It took a while sure, but plants have been profitable for 30 years now, and could have continued to be so if they hadn't by law been prohibited from upgrading and researching.
Nuclear regulation in most places goes as follows: is nuclear profitable? if yes, increase safety until it stops being so. If technology improves so that the same safety can be achieved using less cost, further improve safety. If this happens while building a new plant, force them to start over. For what that looks like, look to the 3 complete restarts due to previously approved safety measures suddenly being retracted and increased during the construction of the Finnish plant.
Its this idiotic idea that they must guarantee zero percent risk which is the main culprit. Flying kills more people, and more people need power than flight, yet we require far more of nuclear. Many countries built dozens of perfectly safe plants during the 60ties for pennies on the dollar. If we could build those again, you know the ones where less than 0.25% had an serious accident over a 60 year history, and removed the massive taxes, we could have power prices at a fifth of what they are today.
Umm, it's not the safety regulator's task to promise the results will be sufficient if you use a specific methodology: "Scrum methodology is fine, so the resulting software quality will be fine too."
Nuclear is much cheaper when built at scale, with multiple copies of the same design. Serial production of nuclear plans in the 70s produced plants at a cost of about 2 billion per GW of capacity. And bear in mind that nuclear's capacity factor is over 90% as compared to 25-35% for wind and solar. And it's not an intermittent power source, eliminating the need for storage.
The reality is that we don't have the capacity to fulfill energy demand without controllable sources. You can't just say, "well it's cloudy and not very windy. Guess plumbing just isn't going to work today because we can't power the pumps." Well, you can but you'll immediately get voted out of office and replaced with someone who will build fossil fuel plants to keep the country alive.
Nowhere nuclear got economic, required massive subsidies - and in the end has been driven by the need for the precious byproducts?