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Small nuclear reactors: tiny NuScale reactor gets safety approval

popularmechanics.com

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Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#311

Post by Ericson2314 »

pfdietz wrote: post #281
EricE wrote: post #12

This is huge. Not only are micro reactors far more economical, it dramatically reduces the need to maintain a massive nationwide grid and provides flexibility to people in remote areas including greater autonomy. Efficiency should be greater without massive transmission line losses. Might start fewer fires in California too.

> Not only are micro reactors far more economical Experience to date has been the opposite. They have diseconomies of scale in construction and operation. The proponents claim they will make up for this somehow, for example by making the reactors in factories, but note that NuScale has given up on that and is going to have the parts fabricated by others and assembled on site, just like larger reactors.

Source for that plan B? Curious what they are telling their investors, then.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#312

Post by wahern »

jhallenworld wrote: post #52

Here is the NRC website about this reactor: https://www.nrc.gov/reactors/new-reactors/smr/nuscale.html Here is an interesting sub-report: https://www.nrc.gov/docs/ML2022/ML20224A525.pdf Information withheld for security reasons. One item concerns the "ultimate heat sink". What happens when the ultimate heat sink is lost? Well a design assumption is that it is not lost: https://www.nrc.gov/docs/ML2020/ML20205L410.pdf…

> DHRC is decay heat. CNV is reactor containment vessel. So drain the pool and the reactor is in trouble.

In some reactor designs overheating slows and eventually stops the reaction in a controlled/deliberate manner. The reactor system may still fail irreversibly, but it wouldn't necessarily meltdown in a way that risks widespread contamination or excessively expensive site remediation, such as by exposing unapproachable material.

I have no idea if this design has that quality.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#313

Post by patmorgan23 »

dheera wrote: post #271
ses1984 wrote: post #157

Earlier quoted context omitted.

There's no research being done on materials to safely contain molten radioactive salt, that research could be dangerous, pretty much only superpowers would have the resources to do the research.

> materials to safely contain molten radioactive salt Wouldn't a giant steel or stone vat work, in theory?

You'd still need a heat exchanger at some point, and you want a lot of surface area and thin walls for that.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#314

Post by tominous »

et2o wrote: post #309
jjoonathan wrote: post #169

Earlier quoted context omitted.

Have people really found no way to dump it in an emergency with t^4 transfer?

What is t here?

I assume they meant T^4 radiation (Stefan-Boltzmann law): https://en.m.wikipedia.org/wiki/Stefan–Boltzmann_law

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#315

Post by ses1984 »

ClumsyPilot wrote: post #300
ses1984 wrote: post #193

Earlier quoted context omitted.

It's a people problem. People are fallible on the best days, assuming everyone did their very best from nuclear physicists to construction workers, mistakes are made. You take steps to reduce the risk. Research gets review. Engineering schematics get review. Construction gets inspection. Still some mistakes will get through. And people always act their very best all the time right? You can even have a perfect design,…

A sufficiently large pool can be built, that any plausible leak will take many days. Think about it: a million liters of water take a long time to dissapear, after all lakes stay there for a long time without rainfall. Weve built many many ponds, it's not hard.

I'm not sure it's that simple.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#316

Post by curiousllama »

freeopinion wrote: post #241
RhodesianHunter wrote: post #58

Earlier quoted context omitted.

This is IMO a positive for nuclear, not a negative. You're forced to confront the cleanup as opposed to fossil fuels, where you just blow your waste out into the atmosphere and make it the commons' problem.

We don't have a good track record of confronting the cleanup of nuclear waste. The US federal government recently shipped a secret load of waste into Nevada. Nevada was very unhappy about that and claimed it was done in secrecy because it was illegal. After a bit of a fight, the feds caved and have agreed to remove the waste. There is no plan for this stuff. The repository that was built in Nevada was never actually…

The only proper source

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#317

Post by natmaka »

pvaldes wrote: post #277
godelski wrote: post #150

Earlier quoted context omitted.

Nuclear sites are designed to withstand a strike from a commercial airliner (747). Like you, the designers imagined many of the events you mentioned and more. A good rule of thumb is that if you, a non-expert, can think of a scenario within 10 minutes, an expert has probably already thought of this scenario. Nuclear power plants and weapons sites have always been considered targets and thus considered extra scrutiny…

> the designers imagined many of the events you mentioned and more Designers are awesome. Sadly they were also unable to find some time in 50 years to raise a wall a few m so it can stand a Tsunami. It seems that the extra scrutiny, was not so extra in the real life when the company will need to allocate real money.

You don't even need a tsunami, as a plain immaterial "cascade" can wreak havoc: https://en.wikipedia.org/wiki/Forsmark_Nuclear_Power_Plant#J...

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#318

Post by pfdietz »

Ericson2314 wrote: post #311
pfdietz wrote: post #281

Earlier quoted context omitted.

> Not only are micro reactors far more economical Experience to date has been the opposite. They have diseconomies of scale in construction and operation. The proponents claim they will make up for this somehow, for example by making the reactors in factories, but note that NuScale has given up on that and is going to have the parts fabricated by others and assembled on site, just like larger reactors.

Source for that plan B? Curious what they are telling their investors, then.

"In answer to a question I posed to Nuscale at the town hall we have learned that the plan to save costs by fabricating the modules at a remote factory and shipping them to the Idaho site has been abandoned. The artful response to my question said that Nuscale engaged with approximately 40 … pressure vessel fabricators worldwide and … determined that Nuscale will use existing factories … in lieu of building its own factory.

The major module subcomponents will be manufactured at multiple manufacturer locations and shipped to a single location for assembly prior to installing into the facility.” This signifies the failure of one of the major cost-saving features of the Nuscale project, which was to forestall this exact scenario."

https://losalamosreporter.com/2020/08/22/get-out-of-the-fluo...

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#319

Post by godelski »

et2o wrote: post #310
godelski wrote: post #152

Earlier quoted context omitted.

Nuclear power plants were designed with this in mind. It would take a substantially larger earthquake to damage a nuclear power plant and cause it to leak than a commercial pool. Such a comparison is in bad faith and disingenuous.

It’s not bad faith or disingenuous. Fukushima happened because of an earthquake, remember?

An earthquake that was one of the largest ever recorded and resulting in one of the largest tsunamis ever as well. So you know, pretty common circumstances.

Re: Small nuclear reactors: tiny NuScale reactor gets safety approval

#320

Post by natmaka »

godelski wrote: post #240
Klinky wrote: post #166

Earlier quoted context omitted.

You're underplaying the danger and overplaying the value. Who exactly is investing in this "green gold"? If it's so valuable why does no one actually want it, and why is the DoE stuck with half a trillion liability?

> Who exactly is investing in this "green gold"? France[0] > If it's so valuable why does no one actually want it, I mean France does... we actually gave them the tech. The reason we stopped is more political. But more people do this than just France, but they are the biggest example since 17% of their entire grid is powered from recycled nuclear. The other reason we don't do it is that it is just cheaper to buy more…

In France this 'success story' led to a state law (2015-992, from 2015, the "loi relative à la transition énergétique pour la croissance verte") stating that the part of nuke-produced electricity must fall to less than 50% in 2025, from 72% then, and that renewables must replace it.

In France nuke-power is backed by gas (which produced 10,3% of gridpower in 2017).

The sole reactor currently planned (Flamanville-3) is a complete disaster, more than 10 years behind schedule and 4x overbudget.

https://en.wikipedia.org/wiki/Flamanville_Nuclear_Power_Plan...

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