Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

What is a molten salt reactor?

thmsr.com

Post reply on HN
Print view View original

91–100 of 107 posts

Re: What is a molten salt reactor?

#91

Post by mlyle »

ncmncm wrote: post #56
mlyle wrote: post #48

Earlier quoted context omitted.

> In the meantime, we build out the renewable generating capacity. We're already dipping into times of negative electric power cost in places with high renewable penetration... and a whole lot of the rest of the day where storage is needed, and a whole lot of usages that are not electric yet which will increase demand. Yes, more renewable build out is necessary and helpful. But it won't get us low enough in carbon in…

Diverting money from renewable build-out for contraptions that will not deliver any energy at all year after year would, then, be strictly worse.

I'm not proposing diverting money from renewable build-out. But surely we can also build a few conventional plants for nuclear base load for all the additional heating, industrial, etc, demand we'll have as things electrify... and try a prototype design or two to gain information.

It's not like there's one purely fungible pool of resources to build all things and solve all human problems.

Diversity in approaches is way better than your all-eggs-in-one-basket strategy.

Re: What is a molten salt reactor?

#92

Post by mlyle »

aliswe wrote: post #86

> In essence, a molten salt reactor [MSR] is a vessel that contains a hot liquid salt which a nuclear reaction takes place The tl;dr on the page is missing a crucial word near "which", making the sentence nonsensical to me.

"in which"

Re: What is a molten salt reactor?

#93

Post by mlyle »

ncmncm wrote: post #64
tomp wrote: post #62

Earlier quoted context omitted.

It would also be amazing if you posted any sources, or examples. All we know is that France has cheap electricity (nuclear) and Germany majestically fucked up by shutting down nuclear, wanting to build renewables, and in turn ended up addicted to Russian carbon drugs.

That is a favorite trope of nuke boosters, but is false . Everyone repeating it knows this: Germany was always dependent on fossil fuels. They have been adding wind turbines at a breakneck pace, getting incrementally less dependent. Fixing those ramshackle old contraptions would have cost much more per unit power out. They have already built out more wind generating capacity (averaged) than the reactors shut down pro…

> France is not building new nukes, nor even patching up old ones, because it is extremely expensive, and not getting any cheaper.

False! https://www.france24.com/en/europe/20220210-announcing-new-r...

Re: What is a molten salt reactor?

#94

Post by ortusdux »

irjustin wrote: post #47
ortusdux wrote: post #29

Earlier quoted context omitted.

I've been working on molten salt reactor claddings for a few years now. MSRs are very safe. First, there are two main groups of molten salt systems. One group uses generic salt to transport heat. This usually provides efficiency gains over water based systems. These are the systems that might leak sodium and it's no big deal. The 2nd kind of system uses a salt with the fissile material dissolved in it. This is what t…

> These are the systems that might leak sodium and it's no big deal. Sorry can you back this statement up with more than "it's safe, trust me"? I'm not knowledgeable enough to say if this statement can be accepted at face value. History has shown that's not enough. But to me, any system that leaks by accident is a disaster waiting to happen on time scales that power plants are expected to operate on.

I think that you are conflating two different types of systems.

There are systems that use molten salt to transport heat. Several types of power generation systems are more efficient above the boiling point of water. The most famous of these would probably be solar collectors. The efficiency gains are higher at increased operating temperatures, so these systems are usually pushed to their limits. These can leak without causing an international incident.

Molten salt reactors, MSRs, are nuclear reactors that use a liquid fuel in place of a solid one. As far as I know, only a handful have ever been built and reached criticality. These were all done in the 50's and 60's. These systems have secondary and probably tertiary containment vessels in the case of leaks.

These are two very different, but often conflated, systems. Part of the reason for this is that many MSR designs use a secondary molten salt loop as a temperature step-down.

Here is the Wikipedia diagram for a MSR. Note the fuel salt loop, the molten salt coolant loop, and the steam turbine.

https://en.wikipedia.org/wiki/Molten_salt_reactor#/media/Fil...

Re: What is a molten salt reactor?

#95

Post by ncmncm »

mlyle wrote: post #90
ncmncm wrote: post #70

Earlier quoted context omitted.

I guess that is my answer.

Your answer is that these exact issues have been studied for >50 years, and had reasonable answers back then: http://moltensalt.org/references/static/downloads/pdf/ORNL-T... Almost all largely workable decades ago before we had e.g. laser welding, modern remote welding, industrial robots, etc. Of course things are better now. (Also, of course, we'd have to learn a lot operationally to actually do it). Still, obviousl…

There is no hurry. We got there in the end.

Re: What is a molten salt reactor?

#96

Post by mcv »

rpdillon wrote: post #88
mcv wrote: post #75

Earlier quoted context omitted.

I've been hearing for years now how fantastic Thorium is, but with every new article, I wonder: so where are all these new fantastic Thorium plants? If they still don't exist, then surely that suggests it doesn't work, doesn't it?

My current hypothesis is that nuclear became politically toxic in the 80s, and public will to support nuclear research evaporated, leading to everyone thinking "nuclear == light water reactor", and the entire field of research on fission-based nuclear stagnated as a result. I'm not an expert though, just interested in the topic. I read up quite a bit on MSR and LFTR a decade ago and concluded that it was really inter…

There's a lot of different countries in the world, and politics isn't the same everywhere. At the moment there are apparently 55 nuclear reactors under construction. No idea if any of them are Thorium MSRs.

Re: What is a molten salt reactor?

#97

Post by ortusdux »

ncmncm wrote: post #46
ortusdux wrote: post #29

Earlier quoted context omitted.

I've been working on molten salt reactor claddings for a few years now. MSRs are very safe. First, there are two main groups of molten salt systems. One group uses generic salt to transport heat. This usually provides efficiency gains over water based systems. These are the systems that might leak sodium and it's no big deal. The 2nd kind of system uses a salt with the fissile material dissolved in it. This is what t…

If you find "materials the storage vessel is made of" in the salt, do you shut it down and abandon it? Alternative would be to drain it into a holding tank and, what, send somebody in to fix it? Who?

Keep in mind that only a few MSRs have reached criticality, and they were experimental units operated in the 50's and 60's. This article and all of this talk is about "Gen IV" MSRs, which, AFIAK, are all currently in the design an testing phase.

Salt chemistry monitoring is a critical part of a MSR operation. The fissile material is slowly exhausted in the reaction and needs to be replaced, while the byproducts need to be removed. The nuclear reaction causes some transmutation of every element it irradiates, which means you get a predictable but diverse set of contaminants that need to also be removed.

The molten salt corrodes everything it comes in contact with, and the radiation also degrades the materials in wild ways. One study I read estimated that directly exposed tungsten would transmute into rhenium at the rate of 1% per year, and that the newly created rhenium would transmute into osmium at the same rate. Basically, it will take an army of people much much smarter than me to plan for all the issues that might come up during the operation of a MSR.

There are many startups backed by billions of dollars trying to find a good solution. One of my favorites simply designs in 8 containment vessels and a crane into the reactor chamber. They plan to just pick up the top of the reactor and move it into a new vessel every 7 years or so.

Re: What is a molten salt reactor?

#98

Post by [deleted] »

ncmncm wrote: post #71
seanhunter wrote: post #65

Earlier quoted context omitted.

Rather than stating that their (sourced) claims are false, perhaps you could post some sources for your claims instead? For example, it would be great to see references for the cost of storage and why storage isn't being built yet.

It is easy to lie by mis-citing sources. Read what the sources say, not what he says.

[deleted]

Re: What is a molten salt reactor?

#99

Post by Blackthorn »

aldarion wrote: post #89
mcv wrote: post #75

Earlier quoted context omitted.

I've been hearing for years now how fantastic Thorium is, but with every new article, I wonder: so where are all these new fantastic Thorium plants? If they still don't exist, then surely that suggests it doesn't work, doesn't it?

Europe is shutting down nuclear power plants because apparently a lot of people (and many politicians) believe they will cause us to glow in the dark. Insanity.

Here in New York, a perfectly functional nuclear power plant was shut down in order to replace it with 3 natgas plants. Right before the price of natgas spiked too, leading to everyone's electric bills doubling. Lobbying.

Re: What is a molten salt reactor?

#100

Post by ncmncm »

mlyle wrote: post #93
ncmncm wrote: post #64

Earlier quoted context omitted.

That is a favorite trope of nuke boosters, but is false . Everyone repeating it knows this: Germany was always dependent on fossil fuels. They have been adding wind turbines at a breakneck pace, getting incrementally less dependent. Fixing those ramshackle old contraptions would have cost much more per unit power out. They have already built out more wind generating capacity (averaged) than the reactors shut down pro…

> France is not building new nukes, nor even patching up old ones, because it is extremely expensive, and not getting any cheaper. False! https://www.france24.com/en/europe/20220210-announcing-new-r...

I am updated with new information as of 2022/02/10.

More the fools them.

Post reply on HN