I would expect that there have been multiple nuclear power plants that provide a net positive return, specially on countries like France where 70% of their energy is nuclear.
However a reasonable argument can be made the public benefited from externalities like lower pollution and subsidized electricity prices even if it was a money pit and much of the benefit was exported to other countries via cheap off peak prices while France was forced to import at peak rates.
So while regulations may be overkill it’s not arbitrary only hydro is really comparable but hydro also stores water and reduces flood risks most years. Fusion sill had real risks, but there’s no concern around $500+ Billion cleanup efforts.
How exactly would you get meaningful widespread tritium contamination of groundwater? IE not just the trace amounts you see from existing nuclear reactors.
Groundwater doesn’t flow quickly from a point source and tritium has a fairly short half-life. 60 years later you might be looking at a larger though still small area, but 97% of the stuff will have decayed and what remains is now diluted and doesn’t bioaccumulate.
It’s not going to concentrate around some site after entering the atmosphere the way heavier than air particulate pollution would.
Nearly pure tritium is extremely valuable so we aren’t going to be dealing with some long term leak. You hypothetically might have a large tank with say 1 month of T2 fuel but that would be really expensive directly and waste quite a bit of fuel through nuclear decay over time. Having that much fuel across multiple different systems is more plausible but then requires a wide range of different failures. But let’s assume such an improbable tank catastrophically fails, outside of containment, and then completely burns so the tritium will eventually fall back to earth.
It then has to rain over land, though even then storms don’t release all the moisture in the air, that water must be absorbed into the soil rather than running off or evaporating, where it’s further mixed with groundwater as it slowly seeps deep enough to be collected in some well. Thus even if conditions are perfect you’d have trouble reaching above the legal limit for drinking water.
I mean maybe if you intentionally selected the perfect moment with the perfect weather pattern and the perfect local geography and geology perhaps you’d be over the legal limits for a few wells for a little while until it rapidly decays.
Lurking over all this is the issue that loss of property value doesn't require anyone to actually prove tangible harm. The mere fact that property values were affected is enough for a tort.
When people talk about how safe fusion is they aren’t kidding, even breathing in a significant amount of T2 isn’t particularly dangerous radiologically as density is really low and you will quickly exhale it. Huge quantities would be a larger suffocation risks but then you’re talking multi million dollar accidents simply from lost fuel.
Additionally, the industry as a whole is shielded from the liability that would otherwise have bankrupted it multiple times. Notably, the clean up from Fukushima will likely take over 100 years, requires tech not yet invented and will likely cost as much as a trillion dollars [3]. In the US, there is a self-insurance fund paid into by the industry, which would've been exhausted 10-20 times over from a Fukushima level disaster. Plus, Congress severely limits liability from nuclear accidents, both on a per-plant and total basis ie the Price-Anderson Act [4].
Next, it seems like it's the taxpayer who is paying to process and store spent nuclear waste, a problem that will persist for centuries.
Even with all this the levellized-cost-of-energy ("LCOE") of fission power is incredibly expensive and seemingly going up [5].
Some want to reduce costs by using more off-the-shelf tech and replicating it for scale, most notably with small modular reactors ("SMRs") but this actually makes no sense because larger fission reactors are simply more efficient.
[1]: https://theecologist.org/2016/jan/04/after-60-years-nuclear-...
[2]: https://www.ucs.org/resources/nuclear-power-still-not-viable...
[3]: https://cleantechnica.com/2019/04/16/fukushimas-final-costs-...
[4]: https://www.yuccamountain.org/price_anderson.htm
[5]: https://en.wikipedia.org/wiki/Cost_of_electricity_by_source
Most reactors are old and in need of repair, most of these earlier than planned afaik.
There is also the bigger issue that some reactors are shut down in the summer because cooling water would leave the reactor so hot that it would be a danger to the animals living in the river.