Live data from Hacker News

Making Nuclear Energy Smaller, Cheaper And Safer

npr.org

1–10 of 116 posts

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#2
“NuScale's design doesn't depend on pumps or generators that could fail in an emergency because it uses passive cooling. The reactors would be in a containment vessel, underground and in a huge pool of water that can absorb heat.

That means that even a reactor that fails would still be safe. "It doesn't require any additional water," says Feldman. "It doesn't require AC or DC power. It doesn't require any operator action. And it can stay in that safe configuration for as long as is needed."”

What if there’s a leak? What if for some reason the temperature inside the reactor is slight enough to vaporise the water?

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#3
Although NuScale is not the first to focus on this type of implementation (Westinghouse, Areva, B&W, etc..), namely small modular reactors (SMR), I am glad to see more hands in the mix. As a South Carolina resident (and supporter of nuclear power) and witnessing the shit-show with SCANA and the cancelled VC Summer plants, I am hopeful that economies of scale can take effect in the SMR-based designs.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#4

“NuScale's design doesn't depend on pumps or generators that could fail in an emergency because it uses passive cooling. The reactors would be in a containment vessel, underground and in a huge pool of water that can absorb heat. That means that even a reactor that fails would still be safe. "It doesn't require any additional water," says Feldman. "It doesn't require AC or DC power. It doesn't require any operator ac…

About the water vaporizing: I'm guessing the pool is so "huge" that the sheer amount of energy required to vaporize the water can't be found in the fissile fuel alone. That doesn't account for the possibility of a leak, though.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#5

“NuScale's design doesn't depend on pumps or generators that could fail in an emergency because it uses passive cooling. The reactors would be in a containment vessel, underground and in a huge pool of water that can absorb heat. That means that even a reactor that fails would still be safe. "It doesn't require any additional water," says Feldman. "It doesn't require AC or DC power. It doesn't require any operator ac…

Leaks are designed out because the entire reactor vessels are surrounded by a giant swimming pool. The temperature stays low enough because this swimming pool is passively cooled.

Lack of relible decay heat[1] cooling caused both Fukushima and three mile island accidents. Having passive decay heat removal usually decreases the probability of core damage by about 100x.

1 https://whatisnuclear.com/decay-heat.html

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#6

Although NuScale is not the first to focus on this type of implementation (Westinghouse, Areva, B&W, etc..), namely small modular reactors (SMR), I am glad to see more hands in the mix. As a South Carolina resident (and supporter of nuclear power) and witnessing the shit-show with SCANA and the cancelled VC Summer plants, I am hopeful that economies of scale can take effect in the SMR-based designs.

Is this economies of scale in the right place though?

I'm doubtful we'll ever get to the point where you can just plop a reactor down and go. You're still going to have the years of political wrangling, all the bulky containment and supporting infrastructure.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#7
post #4

“NuScale's design doesn't depend on pumps or generators that could fail in an emergency because it uses passive cooling. The reactors would be in a containment vessel, underground and in a huge pool of water that can absorb heat. That means that even a reactor that fails would still be safe. "It doesn't require any additional water," says Feldman. "It doesn't require AC or DC power. It doesn't require any operator ac…

About the water vaporizing: I'm guessing the pool is so "huge" that the sheer amount of energy required to vaporize the water can't be found in the fissile fuel alone. That doesn't account for the possibility of a leak, though.

In an accident scenario, the heat that is problematic is not from the fissile material (i.e. U235, Pu239) but from the fission products' decay heat - the isotope soup remaining after the fissile atoms split. It is much less intense than the heat/energy produced during normal operation and drops off significantly after a couple days. So the pool's purpose in terms of accident mitigation is to keep things cool enough during the period of time after reactor shutdown and before radioactive isotopes left over from split atoms decay/cool-down enough.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#8
post #6

Although NuScale is not the first to focus on this type of implementation (Westinghouse, Areva, B&W, etc..), namely small modular reactors (SMR), I am glad to see more hands in the mix. As a South Carolina resident (and supporter of nuclear power) and witnessing the shit-show with SCANA and the cancelled VC Summer plants, I am hopeful that economies of scale can take effect in the SMR-based designs.

Is this economies of scale in the right place though? I'm doubtful we'll ever get to the point where you can just plop a reactor down and go. You're still going to have the years of political wrangling, all the bulky containment and supporting infrastructure.

Most likely multiple units will be deployed on each site, allowing them all to take advantage of shared infrastructure like grid connections, spent fuel storage, security etc.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#9

“NuScale's design doesn't depend on pumps or generators that could fail in an emergency because it uses passive cooling. The reactors would be in a containment vessel, underground and in a huge pool of water that can absorb heat. That means that even a reactor that fails would still be safe. "It doesn't require any additional water," says Feldman. "It doesn't require AC or DC power. It doesn't require any operator ac…

Leaks are designed out because the entire reactor vessels are surrounded by a giant swimming pool. The temperature stays low enough because this swimming pool is passively cooled. Lack of relible decay heat[1] cooling caused both Fukushima and three mile island accidents. Having passive decay heat removal usually decreases the probability of core damage by about 100x. 1 https://whatisnuclear.com/decay-heat.html

"Having passive decay heat removal usually decreases the probability of core damage by about 100x."

100x isn't 100% though.

100 of these small reactors has the same risk as one large reactor. Perhaps higher, because like you, everyone goes around saying the risk has been designed out.

Though obviously one small reactor going boom is preferable to a big one doing the same.

Re: Making Nuclear Energy Smaller, Cheaper And Safer

#10
post #8
post #6

Earlier quoted context omitted.

Is this economies of scale in the right place though? I'm doubtful we'll ever get to the point where you can just plop a reactor down and go. You're still going to have the years of political wrangling, all the bulky containment and supporting infrastructure.

Most likely multiple units will be deployed on each site, allowing them all to take advantage of shared infrastructure like grid connections, spent fuel storage, security etc.

Yes I was going to add that their best chance is being put on the sites of old reactors.
Post reply on HN