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Your point about the materials challenge for MSRs is very true: for the designs I've seen the 'solution' is super corrosive. However, I don't think it's an insurmountable challenge, and its more a question of durability over time (and then subsequent maintenance costs). Our water plumbing systems will eventually succumb to the rigours of time; it will just be a very long time...

On waste storage, MSRs product much much less waste. A solid fuel, light water reactor achieves maybe 3% fuel efficiency, whereas it's somewhere north of 90% for the thorium MSR. In addition, the byproducts it does produce are mostly useless for nuclear weapons. Dr Carlo Rubbia (former director of CERN and 2016 Nobel Laureate) has stated one of the reasons funding for MSRs was cut by the US in the 70s was precisely because it's difficult to use them to produce nuclear weapons. There are even proposals for MSRs that are fuelled specifically by nuclear waste transuranics (e.g. http://www.transatomicpower.com/wp-content/uploads/2015/04/N...).

Honestly, I'm not so sure the ROI for renewables is anywhere close to 'winning', unless you ignore stuff like renewable intermittancy (meaning you need to build a crapload more highly expensive transmission infrastructure, or attach highly cost-effective batteries to the grid i.e. lead-acid batteries atm).

As for German nuclear, I suppose that won't be a problem once they've completely shut down all their nuclear reactors. Pity that the government official estimated cost of this is 55 billion Euros over the next decade. Although the (frankly more credible) 'unofficial' estimate puts the cost at 250 billion euros over the next decade. Not to mention the fact it's resulted in their co2 emissions increasing in both 2015 and 2016 (https://www.cleanenergywire.org/factsheets/germanys-greenhou...). Their own environment ministry now predicts they will probably not make their 2020 co2 reductions targets.

So other than the enormous cost and increase in co2 emissions, good policy.

Yeah the:

- We could do it for less than $3 Trillion ...

- We could do it for $1 Trillion with liquid-fueled Molten Salt Reactors

Seems very dubious. The first successful MSRs were built over 60 years ago. The reason none are in commercial use is probably because the costs would work out higher than conventional reactors.

Yeah it's possible he's overstating the case, although he seems to have gone in to quite a bit of detail estimating the costs. But you'll see from some of the comments above those might be distorted.

My own very crude back of the envelope, for replacing all worldwide coal generation with AP-1000s (at $7bn a pop) puts the cost somewhere in the $6T range. This is assuming I got the unit conversions correct...

As for MSRs, there's some very interesting history there. There is, of course, the fact that MSRs weren't as good at producing the necessary byproducts for making nuclear bombs (remember this was during during the cold war). But the other accident of history was simply that Oak Ridge National Labs (who ran a prototype MSR for a few years) just happened to be in the wrong part of the country: the story goes that Nixon apparently wanted to shore up political support in (California?...) and so pushed money more in the direction of the LMFBR.

Nixon also fired the director of ORNL too, apparently because his support for MSRs and advocacy for increased nuclear safety didn't gel too well with that administration. At that point MSRs were kind of forgotten about...

I didn't know the Nixon stuff. Nick Touran has a good summary of the practical difficulties if you haven't seen it https://whatisnuclear.com/reactors/msr.html#problems

Thanks for the link, it's an interesting read.

It definitely seems like the big challenge for MSRs is of the materials/chemical engineering variety. I guess some of these could be designed around: for instance I've heard Kirk Sorensen (LFTR advocate) suggest situating the entire reactor and plumbing complex in a drain/basin of sorts. In the case of a pipe break the fuel(s) simply drains in to a passively cooled storage tank (deep underground).

Also some of the chemical handling would require great care. Fluorine, for instance, is not something I'd want to mess around with...

My experience with development cost estimates suggests the easy parts are easy and the interesting parts might as well be splatter-paint.

> It's no coincidence that the only success story for nuclear is a country where all reactors are government-owned and don't have to turn a profit necessarily.

I don't have the numbers, but I would also have to imagine that the government-owned reactors are the most expensive on paper because there will always be political powers that will want to make it appear more expensive than it is.

Well, France has no reason to do that – they (with > 80% nuclear) have every reason to make them seem as good and effective as possible.

> And you want to give those governments nuclear reactors? Iran, Pakistan, Nigeria, etc?

No, we want to sell them access to our grid and cheap power.