Readit Newshairytrog commented on Japan PM’s solution to dire birthrate has already been rejected by young theguardian.com/world/202... · Posted by u/mindracer
one solution to maintain stable population despite low birth rates is to selectively birth women. japans 1.3 babies per women would more than sufficient. read about it here: https://lvenneri.com/blog/sexratioed
Very important point. Calling new designs safer is buying into the narrative that older designs are unsafe, which is simply untrue.
It's like saying new t-shirts are more wearable.
IT kind of is true. Sure the death count directly attributable to nuclear reactors is low. But Fukushima caused the entire countries fleet to shut down - to the present day. Safety isn't about lives lost or health, it's about financial repurcussions of the accidents - both directly at the site (take a look at Fukushima today) and the effects on the wider industry, shutting down all the surrounding power plants, and forcing Japan to import fossils to compensate.
I don't really have an opinion on the matter and I think it's a fair question to consider, but I'll note that the NRC obviously disagrees. At least for now, they could always change their mind. I seriously doubt that they would ever significantly reduce the exclusion zone requirement for any of the currently operating reactors, however.
I think that's fair. I bet new large power plants will get the NuScale treatment and reduced exclusion zone though.
Molten-salt-fuel reactors, as described in this article, are so lame... "It's already melted, so you can't have a meltdown." lol. More seriously, molten-salt-cooled reactors have some promise. They use solid fuel, usually TRISO particles, and are cooled by molten salts, which we now have lots of experience with from solar salt power systems. If you are interested in molten-salt-cooled reactors outside of this lame press release - check out Kairos Power. Their website sucks butt. But they are the main player in molten salt-cooled reactors - funded by Henry Laufer of Renaissance Technologies. They actually have the engineering and financing to get one built, and are reportedly doing very well with NRC (unlike OKLO - lolz).
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Worth noting that this is not really unique to this reactor, and the technology has been around for a while (including multiple basically fully functional demonstration reactors that were actually built, though they weren't without their technical issues). NuScale's design for example, which is a very different design and also much closer to commercial rollout, has a similar greatly reduced need for a large exclusion zone (https://www.nei.org/news/2018/nrc-staff-agrees-smrs-wont-nee...).
This article is reporting on what amounts to a paper reactor design, which is really only like 0.1% of the effort required to actually build. There are plenty of good design concepts for new and fancy reactors, but the business, regulatory, and PR side is where the challenges really lie. But this general technology is a big deal in the nuclear industry right now and it seems increasingly likely that they might finally build some fully functional plants. Strictly speaking they are actively building some MSR plants, but given the not great track record of actually completing new nuclear plants I will remain pessimistic until they are ready to go critical.
Not sure it's a justified reduction in exclusion zone. Yes they use natural circulation to get rid of decay heat if they lose power to run the pumps. BUT - they can't tolerate multiple reactors failing at once, they can't tolerate more than a few control rod withdrawals, and they can't tolerate clogging of the flow channels - Which to me, seem like reasonable accidents. The reduction in exclusion zone for NuScale is not really justified. If they get a reduction, you can expect the big ass reactors to also get a reduction...
What you say is technically true but you're forgetting decay heat. The fission chain reaction stops if you remove the moderator in any sane LWR design, but the fission products in the fuel will continue to generate a very large amount of heat for quite a while. This is exactly what happened at Fukushima and TMI.
https://en.wikipedia.org/wiki/Decay_heat#Power_reactors_in_s...
Some reactor designs can dissipate this decay heat with passive circulation, while most require active pumps to circulate for a while after shutdown. But a total loss of coolant is probably going to result in fuel melt to some extent.
Which is equally a problem for a molten salt cooled reactor. If molten salt leaks or pumping stops, you're gonna get a melt down in your molten salt reactor. That is unless it's running at super low power density - like these guys: https://www.usnc.com/mmr/, in which case no cooling fluid or pumps or even natural circulation apparently are needed to keep it from melting.