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Comment by whearyou | Hacker News Reader

Until fail-safe fission technology is ready (unlike fail deadly technology which all current and planned systems currently are) nuclear power seems to me a sophisticated example of cutting off your nose to spite your face

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If by fail safe you mean that powering off the reactor makes it cool down then the Navy uses fail safe reactors. Water is used as the moderator to absorb radiation. When water is heated its density decreases (edit), thereby making it a less good moderator of radiation. This effect lowers reactor reactivity and heat output. This effect is combined with various devices to produce what is called an inherently safe design. Losing power will not make the reactor have a fuel element failure or melt down.

Fail safe means that in a catastrophic failure of the reactor’s regulatory systems it stops functioning rather than overloads. Entropy trends it to not working rather than working too much - for example a gas furnace will stop burning if the systems running the furnace stop working and are unable to provide more gas to the burn chamber.

Is that how Navy reactors work?

Chernobyl used a neutron moderator with a positive temperature coefficient of reactivity (liquid sodium), while U.S. Navy reactors use water, which has a negative coefficient of reactivity. The more energy you put into the water surrounding the reactor, the less reactive it allows the reactor to be. This has a stabilizing effect on the system. U.S. Navy reactors are inherently stable and inherently safe. To answer your question directly, yes entropy will trend toward making the reactor produce less heat with no intervention.

Chernobyl did not use liquid sodium. It was a graphite moderated thermal spectrum reactor with water as the coolant.

I appreciate the correction. I had fusion of knowledge with a different reactor accident. https://allthingsnuclear.org/dlochbaum/nuclear-plant-acciden...

Burning coal instead of nuclear seems to be a rather unsophisticated example of cutting off your nose to spite your face

Or, to snark on the other half of that post: Instead of building power plants that are deadly when they fail, we'll just build power plants which are deadly all the time.

Hint: no one is building coal plants. Coal is being phased out. Your competition is not coal.

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