Responses to your points above:

1. IPCC Integrated Assessment models don't dictate technologies. By design, they assume many different future scenarios and calculate impacts from those scenarios. Some scenarios use ample amounts of BECCS to achieve negative emissions to hit a 2C target by trading off more short term emissions with expensive negative emissions in the future. This isn't a determination of what is needed, just an example of a technology scenario that hits an emissions target. Massive amounts of BECCS would be extremely expensive; IAMs don't factor in these economic factors. However BECCS may be needed to get negative emissions. Nuclear can't do that, and will need to compete economically for energy production. If you think nuclear is absolutely necessary, please send me the particular IAM that states that and the economic assumptions compared to other electric grid build-outs.

When I speak of the academic community here, I'm referring to the community doing resource planning and grid modeling - the people that are making the decisions about what grid resources, transmission, and R&D to pursue. In this community, nuclear is not recognized as a substantial contributor to short term or long term decarbonization.

2. Break out the capital cost figures. Licensing and regulation isn't the major difference. That accounts for less than 10% of the cost; The World Nuclear Association (nuclear lobbying group) puts it at 5% of the cost. The $3k figure in China is because labor is much cheaper there, which is also a reality for renewables.

https://www.world-nuclear.org/information-library/economic-aspects/economics-of-nuclear-power.aspx

On cost - I'll make the point again - even with heroic capital cost reductions, nuclear won't be competitive in the market. The O&M and fuel costs associated with rankine-cycle based power production cannot compete with VRE. Even the most nuclear pro lobbying groups can't claim nuclear is competitive using recent data (the link above compares to 2012 prices). Nuclear plants are closing now because even with O&M costs, they are more expensive than new VRE.

The same economics apply to coal plants - large rankine based producers with substantial fuel costs.

https://carbontracker.org/coal-developers-risk-600-billion-as-renewables-outcompete-worldwide/

The slight difference is that coal also has to contended with large capital expenditures on criteria pollutant emissions controls (in most countries), whereas nuclear has larger capital cost requirements for the reactor.

3.

a) On LCOE vs system LCOE. Marginal LCOE is what determines what new generation resources get built. In fact, utilities have an obligation to consumers to pursue lowest cost generating resources as overseen by the public utility commission. No one uses total system levelized cost in planning, and it's not clear how one would even do that. If this was Sim City and you could plan out the eventually 50 year grid from the beginning could you do it? Maybe, but it may not be centralized generating resources. As for high VRE costs, there isn't "betting" on the cost inflection point for VRE- we have very accurate models of the electric grid and build-out concerns. Electric battery storage is already cost-competitive with gas peakers in some grid regions. And as VRE increases, the marginal LCOE will tilt in favor of load shifting, DR, and storage assets instead of gas peakers, gas CCs, and certainly baseload coal and nuclear plants which have to earn revenue in the production and capacity markets to stay viable.

In a high VRE scenario, it's not clear that added nuclear or any baseload generator is the cost-preferred option to extra VRE with curtailment or even existing storage costs. Saying baseload generators are a solution needs supporting evidence, especially including how the market would need to be restructured to keep these plants viable.

b) On the point of political feasibility - eminent domain is an issue regardless of generating source. Gas lines, transmission lines, siting uranium or coal mines all have political pushback. Local opposition is much stronger against nuclear and fossil generating facilities in general.

c) Value deflation is an issue for solar, though not so much wind with a higher capacity factor and 24/7 power production. This is where load shifting and DR technology in buildings is likely to become cost-competitive with new generation. Building codes in California are already account for this using a TDV (time-dependent valuation) metric in design, rewarding energy savings during peak evening hours a lot and daytime savings comparatively little.

d) Germany heavily subsidized solar, providing the market incentive that brought the price down considerably for everyone else. And now subsidies are no longer needed to make wind and solar competitive - in general, they are the cheapest generating source on their own. But to claim the subsidies failed looking only at historical solar build out in Germany alone in comparison to the total German subsidy cost is to ignore the massive price decrease it meant for solar globally. I could make a similar claim for nuclear if I weighed U.S. nuclear program costs vs. the first 5-10 years of nuclear production in the U.S.

e) Sure, historical experience, especially recent historical experience should carry weight. No advanced economy has decarbonized. The fastest rates of decarbonization in absolute terms are from VRE, and nuclear is nowhere close. France, used as the common example, is building out VRE and retiring older nuclear plants. Nuclear prices have increased in every developed economy in the last 2 decades.

4. Exxon, Shell, BP are very interested in zero carbon fuels. NREL has a $100 million research project on next gen VRE to biofuels "electrons to molecules" funded by Exxon. Here cost of energy is incredibly important; I'm not sure why you suggest nuclear here? Electricity to fuels is well-paired with renewables to absorb low cost solar and wind during periods of otherwise curtailment.

District heating is a specific application where cogeneration is preferable, and a potential U.S. of SMRs in a few major cities with central district steam systems (e.g. NYC). I suspect a cogeneration application is where we most likely see an SMR demonstration project. For newer district systems, there are competing technologies of heat-pump based ambient loops or four-pipe chilled water/hot water loops that are much more efficient than conventional steam district systems and have lower operating costs that steam-based systems.

As to your point that 45% of fossil fuel emissions are electricity and heat? I assume you got that from Fig 2 in: https://science.sciencemag.org/content/360/6396/eaas9793

The numbers heat 2% + combined heat + elec 5% + elec 26% + load following elec 12% + res/commercial heat 10% = 55%, transportation is 22%, cement 4%, iron & steel 5%, and other industry 14%.

Note that this graph includes other industrial non-energy related CO2 emissions and other gas emissions. Cement production involves emissions from limestone reforming in kilns, and steel mills from coke production. Other industry involves substantial methane emissions from refineries and oil and gas production, as well as ammonia.

Combined heat and energy - where future nuclear has potential economic competitive viability is <5% of this picture.

I don't agree with the view that an "all of the above" strategy that includes substantial support for nuclear R&D for electric production is the least risky from a climate perspective. Even if the R&D budget increases, these funds could be better spent on storage, integration, liquid fuels from electricity, direct carbon capture, market commercialization of several lab-proven technologies, or support for better building codes (75% of grid load). I see it as similar to "clean" coal CCS - unlikely to ever be viable and a distraction to less-risky efforts.