It’s really not, nuclear inherently requires extreme costs to operate. Compare costs vs coal which isn’t cost competitive these days. Nuclear inherently need a lot more effort refining fuel as you can’t just dig a shovel full of ore and burn it. Even after refining you can’t just dump fuel in, you need fuel assemblies. Nuclear must have a more complicated boiler setup with an extra coolant loop. You need shielding and equipment to move spent fuel and a spent fuel cooling pond. Insurance isn’t cheap when mistakes can cost hundreds of billions. Decommissioning could be a little cheaper with laxer standards, but it’s never going to be cheap. Etc etc.
Worse, all those capital costs mean you’re selling most of your output 24/7 at generally low wholesale spot prices unlike hydro, natural gas, or battery backed solar which can benefit from peak pricing.
That’s not regulations that’s just inherent requirements for the underlying technology. People talk about small modular reactors, but small modular reactors are only making heat they don’t actually drive costs down meaningfully. Similarly the vast majority of regulations come from lessons learned so yea they spend a lot of effort avoiding foreign materials falling into the spent fuel pool, but failing to do so can mean months of downtime and tens of millions in costs so there isn’t some opportunity to save money by avoiding that regulation.
Not just to operate, but to clean up and decommission at their end of life. In the UK, for example, early reactors were built cheaply without much consideration/provision for eventual decommissioning. This has left an enormous burden on future taxpayers, estimated to exceed £260 billion, much of it related to the handling and cleanup of vast quantities of nuclear waste [1].
Thankfully new reactors are being financed with eventual decommissioning costs "priced in", but this is another reason why they've become so expensive.
[1] https://www.theguardian.com/environment/2022/sep/23/uk-nucle...
The total high level, dangerous nuclear waste of the entire world since we started playing with nuclear power 70 years ago fits in an American football stadium with plenty of room to spare. "Vast quantities" is a serious exaggeration.
~1,470 m³ "high level" waste totalling ~14,000,000 TBq at year 2100. "High level" waste is that which generates enough heat to require specially designed and managed storage facilitates to prevent spontaneous fires etc.
~496,000 m³ intermediate level waste totalling ~1,000,000 TBq at 2100
~1,340,000 m³ low level waste totalling ~130 TBq at 2100
~2,750,000 m³ very low level waste totalling ~12 TBq at 2100. VLLW is considered safe enough to be disposed at landfill sites subject to certain special considerations. But not until the radioactivity drops below a certain threshold, of course - it still has to be stored at special facilities for many decades until then.
It's a pretty vast and costly problem even if you don't consider this a "vast quantity".
Source for these figures: https://www.gov.uk/government/publications/uk-radioactive-wa...