4 ms·
I still believe it is safer than water cooled plants, but Mr. Gates doesn't seem to have touched the downsides of using sodium [1]: > A disadvantage of sodium
by selcuka 4y ago
I still believe it is safer than water cooled plants, but Mr. Gates doesn't seem to have touched the downsides of using sodium [1]:
> A disadvantage of sodium is its chemical reactivity, which requires special precautions to prevent and suppress fires. If sodium comes into contact with water it reacts to produce sodium hydroxide and hydrogen, and the hydrogen burns in contact with air. This was the case at the Monju Nuclear Power Plant in a 1995 accident. In addition, neutron capture causes it to become radioactive; albeit with a half-life of only 15 hours.
> Another problem is leaks. Sodium at high temperatures ignites in contact with oxygen. Such sodium fires can be extinguished by powder, or by replacing the air with nitrogen. A Russian breeder reactor, the BN-600, reported 27 sodium leaks in a 17-year period, 14 of which led to sodium fires.
[1] https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor#Disadvantages https://en.wikipedia.org/wiki/Sodium-cooled_fast_reactor#Dis...
- belorn 4y agoHow does molten salt solar plants solve those problems?
- tuatoru 4y agoI believe they use salts of other metals, not sodium. But in any case, in a salt the metal has already reacted with something and is unlikely to react further with commonly encountered substances.
- _a_a_a_ 4y agoBecause a salt is an already-reacted substance. Molten sodium and molten sodium chloride are utterly different, for example. https://onlinelibrary.wiley.com/doi/10.1002/cite.202000137 https://onlinelibrary.wiley.com/doi/10.1002/cite.202000137 "In commercial CSP plants, almost exclusively a non-eutectic salt mixture of 60 wt % sodium nitrate and 40 wt % potassium nitrate is utilized. This mixture is commonly referred to as Solar Salt"
- ChrisMarshallNY 4y agoI've heard that salt has corrosion issues. These may also apply to sodium, though.
- selcuka 4y agoThe Wikipedia article says that sodium actually protects metals from corroding, but I am unable to see how that works by reading the citation.
- hermitcrab 4y agoSome very reactive substances react with their container vessel to form a non-reactive 'skin' on the inside of the vessel. I don't know if they applies in this case.
- eig 4y agoIs the heat transfer fluid for these nuclear plants considered radioactive? I honestly don’t know. If so, then if a leak happens I’m guessing you have bigger problems than its chemical reactivity. Any leak is a major nuclear cleanup whether it’s water or sodium. Maybe the chemical hazard is just a drop in the bucket compared to the nuclear hazard, in which case why wouldn’t they use sodium?
- sandworm101 4y agoWith a 15-hour halflife, no matter the initial disaster, any radioactivity problems associated with the sodium coolant would disappear in a few days.
- brindy 4y agoWhat happens if that contaminates something else? I presume that would have a different half life? Not a physicist, so genuine question.
- Waterluvian 4y agoSomeone smarter may correct me but my understanding is that radioactivity doesn’t transfer like that. Contamination means for the isotope to find its way into a system (like a human body) and then stay there, radiating harmful particles from the inside. If you were to be contaminated by ingesting some radioactive sodium, it would still decay and be gone within days.
- hermitcrab 4y agoThe fact that it decays quickly also means that it would be very damaging if it got inside you somehow before it had decayed.
- nine_k 4y agoNo, the half-life is a property of a nucleus, which does not take part in chemical reactions. The normal way of dealing with cases of taking in radioactive abd bio-active elements, like iodine, sodium, (and even strontium which tends to take place if calcium), is taking excessive amounts of the same element, but a normal, stable isotope. Taking in some excessive table salt (cheese and chips anyone?) should be pretty easy.