(sorry if my last message came across a bit pissy btw dude, I'm having a rough day but I didn't intend for that to come across like I worry it might have done)

I get what you meant about the bunker, but the long-term solution still hinges on some type of bunker that doesn't exist yet. Some of the issues with projects like you mentioned: areas like you described are very rare. Very little of the planet is a decent distance away from human settlements and habitats, and even if the local water table isn't adjacent to anything important, the nature of the hydrological cycle and the patterns of settlements and habitats mean that contaminated water from some inevitable, unforeseen failure modes will eventually run somewhere that there's wildlife, and then everywhere that there's wildlife. Also, digging giant caves both in mountains and other rock, ensuring they're structurally sound (even just for centuries), then shipping the building materials out to the site, constructing a sealed container large enough to be useful, then ensuring the safe transport of nuclear waste to the site is an overwhelmingly enormous infrastructure project filled with failure modes, and all that for what amounts to creating a single landfill. We don't even know how to build enough of these to store the enormous amount of waste we already have, let alone enough to accommodate the massive amount from any serious increase in nuclear's generation capacity. All this is to say that yeah we can temporarily manage some amount of nuclear waste, but we really can't deal with a huge increase in energy generation like we can with renewables without creating the absolutely colossal problems that insufficient containment of massive amounts of nuclear waste would cause. And even if we could store it all in ideal conditions, our lack of sufficient containment technology would require its continued monitoring and maintenance, possibly long after we're even capable of performing it. Landfills in the event of actual social collapse WILL at some stage (albeit over a very long period of time, but if nobody is around to stop it then that becomes arbitrary) release their contents across the planet alongside all the other landfills, most likely killing everything on it.

How come you don't think that renewables would be able to fill the gap in a degrown energy landscape? And yeah the current most commonly generated forms of renewable energy suffer from intermittancy and (at the moment) curtailment issues, but accompanied by storage systems like flow batteries etc. they're just as compatible with the grid network as the highly tunable generators from coal and nuclear plants. While materials and energy are consumed in the production of solar panels and wind turbines etc., to me at least it's far more preferable to use abundant materials for clean, scaled-back energy generation without the logistical nightmare of creating huge landfills for ticking time bombs we're then charged with maintaining for millennia.