Perhaps a dark thought, and coming from someone not being well versed in these types of high-level analyses: Could this work possibly lend some support to antinatalist/misanthropic points of view?  I should state for the record that I feel tremendous hesitation to these types of views. 

Apologies for beating the nuclear drum again, but I worry that you rely on only one piece of evidence in the following claim, and that evidence is coming from a single person (Jack Devanney) very invested (conflict of interest) in the nuclear industry. Why not use evidence that appears to have slightly less conflicts of interest and that is more aligned with good practice in research, such as peer review?
 

but in practice, nuclear energy capacity has been essentially flat since 1990, in part because of the ability of regulatory agencies to ratchet up restrictions without an obvious limit.

That said, I do acknowledge your use of the qualifier "in part", but I worry that the example is not that helpful - I do not think nuclear energy in the USA would have progressed much quicker if it had less regulation. And in one sense nuclear energy already enjoys one quite substantial benefit compared to e.g. wind and solar: They are not liable for the damage they cause in events such as Fukushima and Chernobyl. Had they been forced to be liable for such damages, that would have added another 5-10 USD to the current, high LCoE for nuclear.

Another example of how regulation is likely not the main issue is the current investment by the nuclear industry. They are not spending most money fighting legal battles on regulation (such as the fossil fuel industry is doing). Instead, they are doubling down on SMRs as the nuclear industry themselves think the best bet of getting costs down is to have smaller plants that as much as possible can be mass manufactured in factories and assembled on site. A lot if not most of the high costs seem to stem from cost overruns due to challenges in project management - challenges that solar and wind overcome by doing minimal customization for each project and instead simply take factory built plants and assemble them quickly on site.

Hi Mike, in similar fashion to my other comment, I think in my pursuit of brevity I really missed underlining how important I think it is to guard against nuclear war. 
 

I absolutely do not think models' shortcomings disprove nuclear winter. Instead, as you say, the lack of trust in modeling just increases the uncertainty, including of something much worse than what modelling shows. Thanks for letting me clarify!

(and the mantra of more detailed models -> better accuracy is one I have seen first-hand touted but with really little to show for it, it is what details you include in the models that drove most of the impact in the models we dealt with which were about 30km x 30km x 5km and using a resolution of 20-200m)

Yeah, I only meant to share some data as it seemed relevant, not to take a personal stance. And I think your point on more nation states acquiring nuclear weapons after a first detonation is a really good one and one that is not captured by the Metaculus questions I referred to. 

Just to be clear: I think avoiding a nuclear war is important and neglected (unfortunately I am less sure about tractability but it should still be pursued). Both the recent nuclear sabre rattling of Putin, the increase in Chinese stockpiles (along with increased US-China tensions) and the withdrawal of the MacArthur foundation from funding disarmament are terrible signs and make me worry about the future. I even applied to a job here at Stockholm-based SIPRI in part because of my worries both about great power conflict and large-scale nuclear wars.

I felt perhaps one point in this article could use some more nuance: I got the feeling from reading this that there is a high likelihood of escalation to a full nuclear war in case of a first strike. I just wanted to say that this and this question on Metaculus might be relevant. The first forecast says there is a ~25% chance of retaliation if a first strike happens by 2024 (most likely the chance of retaliation against Russia). The second question say that if one weapon is offensively detonated by 2050, the most likely total numer of subsequent detonations by 2050 is around 5 more weapons, so quite far away from something that could cause nuclear winter. I do not think this in any way invalidates the concerns about a nuclear winter, I just wanted to provide some forecasts that I came across in my own work.

I want to second the skepticism towards modelling. I have myself gone pretty deep into including atmospheric physics in Computational Fluid Dynamics models and have seen how finicky these models are. Without statistically significant ground truth data, I have seen no one being able to beat the most simple of non-advanced models (and I have seen many failed attempts in my time deploying these models commercially in wind energy). And you have so many parameters to tweak, there is such a high uncertainty about how the atmosphere actually works on a scale smaller than around 1km so I would be very careful in relying on modelling. Even small scale tests are unlikely to be useful as they do not capture the intricate dynamics of the actual, full-scale and temporally dynamic atmosphere.

Hi Paul, thanks for taking the time to respond.

My main concern is the combination of saying contrarian and seemingly uninvestigated things publicly. Therefore, I am only instrumentally, and at a lower priority interested in whether or not nuclear power is over regulated or not (I think nuclear energy is probably less important than poverty, AI or bio). I do not think I need to spend a lot of time to understand whether nuclear power is over regulated or not in order to state that I think it is over-confident to say that it is in fact over regulated. In other words, and in general, I think a smaller burden of proof is required to say that something is highly uncertain, than to actually say whether something is like this or like that with some significant amount of certainty. Instead of going down a potential nuclear energy rabbit hole, I would advise people looking for examples of over-regulation to either pick a less controversial example of over regulation, or if such examples are not easily found, to avoid making these analogies altogether as I do not think they are important for the arguments in which these examples have been used (i.e. the 2 podcasts).

Still, while I feel confident about my stance above and the purpose of my original post, I want to take the time to respond as carefully as I can to your questions, making it clear that in doing so we are shifting the conversation away from my originally stated purpose of improving optics/epistemics and towards digging into what is actually the case with nuclear (a potential rabbit hole!). I also, unfortunately do not have too much time to look more deeply into this (but did on three occasions assess nuclear in terms of costs for powering a civilizational shelter - it did not look promising and am happy to share my findings).

So I will attempt to answer your questions but in order to stick with the main recommendation that I make (to be epistemically humble) my answers are probably not very informative and I think mostly what I am doing is pointing at the level of scrutiny that is required in order to answer these questions with more certainty and especially publicly as a representative of an evidence-based movement.

To your specific questions:

1. I am uncertain if higher adoption of nuclear power would be harmful as this seems like a very complex issue as the impact of energy is complex and entangled with economic, social and environmental considerations, to name a few. That said, and based on a very limited understanding of all these topics, I think the main drawback of nuclear power could be high costs, especially if deployed in low income countries. If nuclear costs remain high, it means such governments have less money for critically needed expenditure on healthcare and education. I am mentioning this as I think it is not clear-cut in a trade-off between environment and global health to always choose the environment. I think, in large part due to being convinced by Johannes Ackva, that the main benefit of nuclear power is to have another tool ready to go in our tool-kit if the transition to a mostly renewables-powered grid becomes challenging. So I think perhaps the best strategy for nuclear power is to be careful in committing to large capital expenditures now, especially in low income countries, and instead to try to get the cost of SMRs down as much as possible. This cost reduction might necessitate quite a bit of deployment so perhaps something like Germany’s support of solar is needed in the SMR space. But again, this is a super challenging topic so I do not want to take any too strong stances here. Moreover, it might not be so much a discussion of whether or not nuclear is net harmful, as finding a way to progress with nuclear in a strategic way that maximizes potential benefits.
2. On safety requirements, I think again this is super complicated and I am hesitant to take any strong stances here. One thing I read while quickly looking at the issue of regulation driving cost was that in the 90s or thereabouts there was a requirement to significantly increase the thickness of the containment room. I have no idea if this would have prevented or minimized damage in past nuclear accidents. Additionally, there might be military considerations (the military, to be sure, puts a lot of spanners in the works for wind energy too with concerns about effect on radars!) as we see with the threat of attacks on the Ukranian Zaporizhzhia plant and the general attention everywhere to security post 9/11. So I think one would need to first identify which regulatory requirements have increased cost and then look at why these were implemented and make an assessment in each case to land on some general understanding of whether these safety requirements seemed overkill or not. And I would push back a bit on the framing I perceive in your question that nuclear power is over regulated. As I commented on the LW post, currently, nuclear, wind and solar have the same number of deaths per unit of energy produced. And the “worst” generation sources like coal and gas is not something we want to aspire to, I think instead we want all generation sources to be safe. For example, I can imagine cost cutting in wind energy from relaxing safety but this would mean a lot more accidents during construction and workers dying at a high rate. I think this is where utilitarian ethics starts having limitations as it seems at least in wind energy to be somewhat reckless to relax safety standards, it simply does not feel right and would not be seen to be proper behavior of the people and organizations involved. I am not sure how relaxing safety standards would play out in nuclear energy, but I would caution against arguing for relaxed safety standards without understanding properly what individuals are likely to be affected negatively, how they would be affected and if this seems like appropriate behavior by the parties involved. That said, there might be cost driving safety in the nuclear that is not likely to have effect on lives - Johannes has done more research than me here and am quite happy to defer to his view that evidence points towards regulation being pursued by the anti-nuclear activists.
3. Whether regulation is responsible for the majority of the cost difference between nuclear and renewables is something I have not been able to easily find quantified assessments of. I think this again points to the complexity of this issue and again I would caution making strong statements here without deeply understanding the various safety requirements and their impact on cost. I think if it was clear that regulation was the main culprit, and that relaxation of regulation would be more or less harmless, then I think most of the pro nuclear lobby would be making strong statements about this. As this seems not to be the case I would at least be much more cautious about assuming something like this. A related observation: Renewables are on a downward cost curve. I have not seen any downward curve in nuclear, anywhere. Thus, even if we manage to get prices down a notch on nuclear by relaxing regulation, projecting forward nuclear power might struggle to keep up with the decreasing costs in renewables.

One thing I have learnt by having worked in and observed the energy industry is to be humble and uncertain. Very few people saw the cost decrease in solar coming. And it might well be that if we had done nuclear instead, we would decarbonize quicker and with a higher likelihood, but I am deeply uncertain having seen how hard it is to forecast such a complex and entangled industry.

Lastly, I am a little uncertain about your second paragraph so please let me know if you think I missed responding to something you said. I am happy to provide the evidence I have come across (not much!) and could also make a clearer statement of disagreement if you think that is appropriate. If so, I would appreciate a bit more detail about what you think I should clearly disagree with.

I think I agree with most if not all of the above (and on some points I would defer to you Johannes having done much more research than me).

Another point you might agree with: Renewables has significantly disrupted the operations and revenues of nuclear. Wind and solar especially ramp quickly up and down with cloud cover and the approach/retreat of weather systems. Existing nuclear is not well equipped to such fast ramp-rates. I think this has made the % of year nuclear power plants are fully operational decrease and that there are "unnecessary" periods where nuclear could have commended high prices but cannot as it takes too long to stop and start these plants. Not too sure about this, but I think I have heard nuclear operators quoting this as a reason for needing to shut down nuclear reactors for commercial purposes.

Yes that seems plausible. But I still think we as a world, and especially we as Effective Altruists, would be better off adjusting to something more neutral and nuanced. My main call is for us to stop overextending and land somewhere closer to a nuanced, evidence-based stance on nuclear power, and ideally also something that does not unnecessarily raise eyebrows from mainstream people. As a movement I think we have enough eccentric takes for the mainstream as it is.