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

Application submitted for US molten salt research reactor

world-nuclear-news.org

Post reply on HN
Print view View original

131–140 of 217 posts

Re: Application submitted for US molten salt research reactor

#131

Post by pfdietz »

ortusdux wrote: post #53
dangerlibrary wrote: post #12

So, 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…

You are correct about the corrosion issue. I've done some work developing molten salt resistant claddings. The main culprit is chromium leaching, which de-alloys most of the metals approved for reactor design. The leeching happens at the grain boundaries, so you will hear 'intergranular attack' as a research focus. A close second problem is the radiation itself. Elements in both the containment vessel and salt transm…

The corrosion issue is part of what drove Moltex to their rather interesting design (sterile coolant salt is a fluoride; fuel salt in tubes is chloride; this is a fast reactor.) The absence of uranium in the fluoride allows it to be operated at a redox potential where chromium does not dissolve.

Re: Application submitted for US molten salt research reactor

#132

Post by iAm25626 »

jxf wrote: post #126
ortusdux wrote: post #53

Earlier quoted context omitted.

You are correct about the corrosion issue. I've done some work developing molten salt resistant claddings. The main culprit is chromium leaching, which de-alloys most of the metals approved for reactor design. The leeching happens at the grain boundaries, so you will hear 'intergranular attack' as a research focus. A close second problem is the radiation itself. Elements in both the containment vessel and salt transm…

> The standard way to test material's resistance to molten salt is to put a coupon in a crucible full of salt for a few hundred hours. Q: What is a coupon in this context?

Great Q: maybe? https://www.researchgate.net/figure/a-MAR-M247Nb-coupon-b-Al...

Re: Application submitted for US molten salt research reactor

#133

Post by pfdietz »

acidburnNSA wrote: post #56
p1mrx wrote: post #38

Earlier quoted context omitted.

> corrosion resistant materials for containing / moving molten salt I'm interested to see what Moltex can do to simplify matters: https://www.youtube.com/watch?v=7qJpVClxzVM&t=758s Instead of pumping the salt around, they plan to leave it sitting in stainless steel tubes, and use simple convection to extract the heat. Oak Ridge rejected this idea in the 1950s because they were trying to power an aircraft, but convect…

LANL built a reactor like that, with liquid fuel in tungsten capsules. It was called LAMPRE. https://www.osti.gov/biblio/4368180-operation-plutonium-fuel...

Tantalum capsules. Molten plutonium is darn corrosive.

Re: Application submitted for US molten salt research reactor

#134

Post by mulmen »

werdnapk wrote: post #118
mulmen wrote: post #104

Earlier quoted context omitted.

Glass is already basically welded, or maybe it's more like brazing. But an oxyacetylene torch can be used to work with glass just as well as to cut or weld metal. Metals also have weird properties. Like tempering and hardening based on temperature. In an industrial setting you need expert welders with deep knowledge of the materials or a weld is going to fail and ruin your day. So it doesn't seem like a huge leap to…

Doesn't glass.... melt?

So does metal. Welding is just melting two parts together.

Re: Application submitted for US molten salt research reactor

#135

Post by AtlasBarfed »

PaulHoule wrote: post #60
2OEH8eoCRo0 wrote: post #48

Earlier quoted context omitted.

They are up against big fossil fuel tycoons like the Kochs. If we are strictly talking corporate propaganda, the fossil fuel industry has plenty of that.

As much as people portrayed an epic battle between renewables and nuclear the real winner from the move away from nuclear was natural gas fired gas turbines. The most obnoxious thing about the energy literature is that it frequently reads like a stopped clock. People still compare the cost of nuclear energy to the cost of coal, but it's no accident that the US stopped building coal plants at the same time it stopped…

Do the gas turbines use the brayton cycle? As I understand gas turbines are around 64% efficient with various tricks. I recall a LFTR presentation talking about how they could use the Brayton cycle because of... ?high temps I think?.

Is the closed cycle gas turbine also using a superior cycle like the Brayton? Oh it's in the third sentence, CTRL-F failed me.

Re: Application submitted for US molten salt research reactor

#136

Post by pfdietz »

powerhour wrote: post #44
EricE wrote: post #28

Way, way overdue! China has taken all of our research from the 50's and has been charging ahead. Very sad that politics and ignorance has severely kneecapped our nuclear industry :(

It's also sad that industry completely failed to convince the population that they can provide a safe solution. For all the credit we give BigCo for creating propaganda, it's curious that they were unable to be successful here, given the stakes.

The problem wasn't the safety, the problem was they couldn't deliver a cheap solution. And recently when they tried to come back they completely fucked it up.

Re: Application submitted for US molten salt research reactor

#137

Post by djcapelis »

jxf wrote: post #126
ortusdux wrote: post #53

Earlier quoted context omitted.

You are correct about the corrosion issue. I've done some work developing molten salt resistant claddings. The main culprit is chromium leaching, which de-alloys most of the metals approved for reactor design. The leeching happens at the grain boundaries, so you will hear 'intergranular attack' as a research focus. A close second problem is the radiation itself. Elements in both the containment vessel and salt transm…

> The standard way to test material's resistance to molten salt is to put a coupon in a crucible full of salt for a few hundred hours. Q: What is a coupon in this context?

A coupon is an informal term for a small sample of material, most often metal. It’s perhaps most commonly used in welding where practice welds for people first training to weld are done on pieces of metal often referred to as coupons. :)

It is usually an artifact of materials like metal which are hard to cut, and can’t efficiently just be cut as needed during a task, but are prepared and pre-cut into small pieces you can grab easily. Each of those pieces is called a coupon.

I used to store mine in a Chinese takeout container box.

Re: Application submitted for US molten salt research reactor

#138

Post by ortusdux »

jxf wrote: post #126
ortusdux wrote: post #53

Earlier quoted context omitted.

You are correct about the corrosion issue. I've done some work developing molten salt resistant claddings. The main culprit is chromium leaching, which de-alloys most of the metals approved for reactor design. The leeching happens at the grain boundaries, so you will hear 'intergranular attack' as a research focus. A close second problem is the radiation itself. Elements in both the containment vessel and salt transm…

> The standard way to test material's resistance to molten salt is to put a coupon in a crucible full of salt for a few hundred hours. Q: What is a coupon in this context?

It's used 2 ways in metallurgy. Mainly it is a term for test pieces cut from a batch of metal and used for proof testing. Tensile, elongation, fatigue, weldability, and many other tests require destructive testing coupons. When you take welding certification tests, you weld two coupons together, and then submit your coupon for testing.

It is also a term for strips of metal that you mount in a corrosive environment as a way to monitor corrosion of other susceptible components. So if you were worried about your bronze bushings, you would buy some matching bronze coupons, put them in an area of similar flow, and measure their thickness periodically.

https://www.alspi.com/coupons.htm https://en.wikipedia.org/wiki/Fatigue_testing#Coupon_tests

Re: Application submitted for US molten salt research reactor

#140

Post by carapace »

ortusdux wrote: post #107
HPsquared wrote: post #68

Earlier quoted context omitted.

Does it even need to be a metal? (Since the pressure is so low strength requirements are lower)... How about ceramic or glass (or quartz), or something else non-metal?

It doesn't, but any material used needs to withstand 4 extremes - high temperatures (650-850 C), corrosion (dissolves uranium), very high neutron flux, and US govt. regulation. Graphite is the current favorite non-metal option. It is already widely used in traditional reactors, so it is approved, and its interaction with radiation is well understood. On the other hand, its interaction with radiation and molten salt i…

Pure speculation here but what about using salt to contain the salt? Make a big block of salt (possibly foamed) and melt a puddle in the middle?
Post reply on HN