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Application submitted for US molten salt research reactor
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Re: Application submitted for US molten salt research reactor
#12So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry.
In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more energy per unit (volume, presumably?) at low pressures, so you can transfer heat indirectly to nearby turbine-turning water without irradiating the water or relying on high-pressure water to cool your reactor. Cool.
But I was under the impression that the main stumbling block for molten salt reactors was that high-energy corrosion resistant materials for containing / moving molten salt simply don't exist (yet). I suppose this is less of a problem for a research reactor, but it doesn't sound like there's been a materials breakthrough here that's allowing them to get started. Are they just plowing forward and they'll need to replace the containment infrastructure every few years?
Re: Application submitted for US molten salt research reactor
#13I thought these were outlawed, per a LFTR video I saw once. To emphasize, I'm asking if that is the case, or was the LFTR video was engaging in misinformation, or if something changed in regulations.
I believe it's less outlawed and more not really approved for use due to insufficient research.
The process for licensing a LWR is well established. Commercial LMFBR (Fermi 1) and HTGR (Peach Bottom 1) reactors have been approved in the US but those were a very long time ago. Anybody who wants to license a new reactor type is going to work through an extensive process with the NRC to determine how exactly it is done.
They built an MSR in Wuwei, China and just got approval to start it.
https://www.world-nuclear-news.org/Articles/Chinese-molten-s...
Re: Application submitted for US molten salt research reactor
#14A 1MW research reactor. Anyway, why is it always a fluoride salt? Is it because of the melting point or because of some nuclear property? I imagine there is some very relevant reason, because a less reactive anion (even chlorine) would be much easier to work with.
Without knowing the specifics as apply to nukes, anion reactivity is inversely proportional to atomic reactivity, fluoride is far less reactive than chloride or bromide or iodide, respectively in order of increasing reactivity. Ergo fluoride and fluoride containing anions are quite common in molten salts/ionic liquids. In English: the flouride, having so voraciously devoured that 8th electron it was missing, really d…
The concern is not so much about the fluoride losing an electron, but about whatever reacted to it stealing electrons from the reactor.
Re: Application submitted for US molten salt research reactor
#15So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine.
I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So both are indirect.
(This is just a nit comment, I think your main points about efficiency still hold, and your materials questions are good!)
Re: Application submitted for US molten salt research reactor
#16So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So bo…
Exactly. In other variants of reactors the inner contour could circulate molten slightly radioactive sodium instead.
Re: Application submitted for US molten salt research reactor
#17So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So bo…
That makes a lot of sense.
I think I was confused by news stories about situations where the reactor has failed in some way, and then there are stories of how radioactive water needs to be stored / disposed of somehow.
Re: Application submitted for US molten salt research reactor
#18So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
Annoyingly, "molten salt reactor" is used to describe two different technologies. What you describe is a traditional reactor that uses molten salt to move heat. This typically leads to higher efficiencies, but does have corrosion issues. Other power generation systems can also benefit from molten salt loops - namely solar energy collectors.
In the research field, "molten salt reactors" (MSRs) usually means the other tech - a reactor where the fissile material is dissolved in a salt. This not only brings efficiency increases, but many safety improvements. Many designs also use a 2nd molten salt loop as a temperature step-down before steam power generation.
Re: Application submitted for US molten salt research reactor
#19So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So bo…
Also, AFAIK, those high-temperature reactors are normally made with a molten metal intermediate cycle (normally sodium) and a gas-only external cycle (normally CO2).
Water enters only to cools the cold side of the external cycle.
Re: Application submitted for US molten salt research reactor
#20So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. This mostly works because moving even very hot, very high pressure water around is kind of a solved problem in industry. In a molten salt reactor, you use nuclear fission to melt various corrosive salts into a fluid, and this is good because molten salts store a lot more en…
> So, in a conventional reactor, you use nuclear fission to heat/pressurize water and then use your hot, slightly radioactive steam turn a turbine. I was under the impression that there was a heat exchanger in the path - that is the reactor turns water into slightly radioacive steam, which is sent through a heat exchanger to turn different water into non (or way less anyway)- radioactive steam for the turbines. So bo…
There are two kinds of conventional light water reactor. In the pressurized water reactor (PWR), the most common, there is indeed an additional heat exchanger between the water in the core and the water that turns to steam. In the boiling water reactor (BWR), the second most common, the slightly radioactive steam from the core goes directly to a turbine.