I assume you meant some large number and that's probably because you are assuming they need to cover all kinds of exaggerated costs like lawsuits from people who get cancer or keeping radiation levels below the background level in case of a leak.
IIRC the bulk is property. German power plants are located in densely populated areas with high property prices. If a plant renders a smallish area unlivable and BMW has to vacate and replace a factory there, BMW will not want to take a loss on that.
If you consider the affected area/MW to wind or solar it's clearly a net win. And there isn't a need to build nuclear plants in more densely populated areas than others.
Germany is well described as a mixture of densely populated and even more densely populated areas, with very few large and sparse areas. (There was a minor scandal a few years ago, after an airplane crash. Each airport has some sort of designated crash site, "dear pilot, if you can't avoid crashing, try to do it there". Some airport's site was near a village, because there was nothing uninhabited nearby.)
Some people appear to tick all three of these:
- My viewpoint is a scientific one
- The liability rules for chemical plants is fine
- The same rules would be too strict for nuclear plants
IMO anyone can combine any pair of those, but considering all three to be true is… very puzzling to me.
If the state no longer limits their liability, but instead applies the same rules to nuclear power plants as it does to other industry, then the average German plants would need to pay €2×10⁹ per year for liability insurance and would have no chance to sell power at anything close to market price.
They can't pay that much because no insurance agency has that scale, so that's out of the question. But even paying the maximum that an insurance agency will accept is out of the question, because even that would make the power too expensive.
My guess is that there'll never be built any, because the renewable fans will make enough noise about this subsidy that the no-subsidies part of the public will be against, and together that's a solid majority.
If the nuclear fans want to build, they have to find safer ways to build and operate, which IMO is an excellent state of affairs, ie. if new plants are built because they're safe enough to insure that's good, and if they're not because they're not, that also good. (I personally suspect that doing it with lower risk requires much research into much more safety-minded organisations than e.g. Tepco was, and if the nuclear businesses have focused on that in the past decade, I haven't noticed.)