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Small nuclear reactors: tiny NuScale reactor gets safety approval

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

#401

Post by p1mrx »

newacct583 wrote: post #115
ColanR wrote: post #103

Earlier quoted context omitted.

No expert, but if it's a pool of water then an earthquake might cause a leak?

Or an attack, of course. Or some other event (social unreset, invasion, coup, etc...) causes an evacuation of staff and it boils off during the resulting excursion. People tend to have poor mental models for the long tail of external failures that happen in real life. It's easy to imagine that things that have never happened in the last century would Never Happen. But... they will, somewhere.

> an evacuation of staff and it boils off during the resulting excursion.

It is trivial to design a system that powers off when unstaffed. Without power, this reactor will SCRAM and passively switch to air cooling over the course of a month.

Presumably, a skilled attacker could compromise the passive safety systems and force a meltdown, but wouldn't it be easier to steal some spent fuel and disperse it?

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

#402

Post by kgabis »

legulere wrote: post #400
manigandham wrote: post #114

Earlier quoted context omitted.

We could dump it into the ocean and not worry about it. There's so much cooling capacity and radiation shielding in the oceans alone that we'd never run out of space, so all of the current disposal strategies are way above and beyond what's needed. Containment is solved problem. It's important to note that other energy types also produce waste. For example, coal ash is incredibly toxic and hard to dispose of, and we…

How do you keep the nuclear waste contained in salt water for thousands of years? The radionuclides will end up sooner or later in the water.

You don't? The volume of water in oceans is so big that this won't be a problem as long as you don't dump it in coastal waters. Keep in mind that there's plenty of reactors from sunken nuclear submarines in oceans right now.

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

#403

Post by candiodari »

i_am_proteus wrote: post #356
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…

Nuclear engineer here. I've read through a good portion of the regulatory submission to the NRC and have a few takeaways that oppose some of the less-well-informed takes in this thread: - The reactor differs substantially from existing PWRs by encasing the primary in double containment, using natural circulation flow for both normal operation and emergency cooling. There are no pumps needed (or installed) to move coo…

> During normal operation, the primary is entirely contained within the primary containment, and circulates naturally, using the differential temperature and gravity. The steam system can is used to remove heat.

If it's using gravity, what happens if this whole reactor gets tilted? What happens at 10 degrees? 45? 90? 180? Are there any critical angles where it would melt down?

I'm curious how you would make such a design that would be both using gravity yet tolerate being moved around.

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

#404

Post by p1mrx »

shortandsweet wrote: post #161
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…

You'd hope so. Reactors yes, but not spent fuel pools. Everyone misses things. I've found 3 design flaws myself in the industry. Not too big of a deal as actions can be taken to mitigate some of the flaws. The other flaws are less probable of causing an issue due to redundant and diverse systems but there's always the off chance...

NuScale claims "The reactor building is able to withstand aircraft impact". The reactors and spent fuel pool are in the same room:

https://www.researchgate.net/figure/Cut-away-view-of-reactor...

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

#405

Post by nix23 »

candiodari wrote: post #403
i_am_proteus wrote: post #356

Earlier quoted context omitted.

Nuclear engineer here. I've read through a good portion of the regulatory submission to the NRC and have a few takeaways that oppose some of the less-well-informed takes in this thread: - The reactor differs substantially from existing PWRs by encasing the primary in double containment, using natural circulation flow for both normal operation and emergency cooling. There are no pumps needed (or installed) to move coo…

> During normal operation, the primary is entirely contained within the primary containment, and circulates naturally, using the differential temperature and gravity. The steam system can is used to remove heat. If it's using gravity, what happens if this whole reactor gets tilted? What happens at 10 degrees? 45? 90? 180? Are there any critical angles where it would melt down? I'm curious how you would make such a de…

>what happens if this whole reactor gets tilted? What happens at 10 degrees? 45? 90? 180? Are there any critical angles where it would melt down?

Ahh i see, a flat earth believer ;)

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

#406

Post by p1mrx »

deegles wrote: post #146
adrianmonk wrote: post #39

Earlier quoted context omitted.

I'm not an expert, but I'm not convinced about it reducing the need to maintain a nationwide grid. Nuclear reactors take ages to ramp up and down. It's basically going to be generating the same amount of power 24x7, but demand is going to fluctuate. The more other areas you're connected to, the more opportunity there is to send that power to someone who can use it. Obviously there's a law of diminishing returns at so…

> Nuclear reactors take ages to ramp up and down. Run them at full blast and dump the extra energy into direct air carbon capture? Of course that would require building the CC plants but it could be planned for.

You'd probably just connect carbon capture plants to the grid, and run them when electricity is cheap for any reason (presumably any fossil sources have no reason to run at this time...)

On a grid with enough opportunistic loads, you'd never need to ramp down reactors.

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

#408

Post by ascar »

marshray wrote: post #67
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.

If only a method for permanent disposal of nuclear waste actually existed.

I always have the feeling many people greatly overestimate the amount of nuclear waste that was actually produced. So far we have produced an estimated 370000 tonnes of nuclear waste globally, which can be stored in about 22.000m³. [1]

This would fit in a 5m high storage facility the size of an American football field (which is even smaller than a European football field). As an additional comparison, the small Amazon fulfillment centers have about 40000m² of area [2] . Assuming the same 5m height, a small fullfillment center is nearly 10 times bigger than necessary to store all globally produced high-level nuclear waste.

Sure, the waste is hard to dispose and dangerous. But it really isn't much.

[1] https://www.world-nuclear.org/information-library/nuclear-fu...

[2] https://www.aboutamazon.com/amazon-fulfillment#how-big-are-f...

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

#409

Post by pvaldes »

manigandham wrote: post #381
pvaldes wrote: post #292

Earlier quoted context omitted.

> We could dump it in the ocean and not worry about it This is the things that make me cringe when I see this people saying again "This time will be different, we promise". Look mum, radioactive tornadoes coming from the ocean...

What do you mean by this time? Nuclear waste has already been dumped in the oceans before (prior to new regulations). 8 nuclear submarines have been lost and there's no environmental impact detected. This has been well studied by several groups including the US Navy, which is one of the biggest nuclear operators with over 80 reactors currently in warships. In the event of catastrophic loss, the plan is to just leave…

Absence of evidence is not evidence of absence. Deep sea ecosystems are extremely fragile and we need to leave them as is if we want to feed people

Time to just get rid of the mess hiding it under the rug and saying that "There is not our fault, it was yet like that when we arrived and now is somebody else's problem" has passed.

We deserve better, much more honest and much more smart people this time.

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

#410

Post by pvaldes »

valuearb wrote: post #348
pvaldes wrote: post #292

Earlier quoted context omitted.

> We could dump it in the ocean and not worry about it This is the things that make me cringe when I see this people saying again "This time will be different, we promise". Look mum, radioactive tornadoes coming from the ocean...

Do you not understand how water dampens nuclear reactions, or how large the ocean is?

Learn about trophic chains, cycle of water in this planet, sea currents, tidal forces and oceanography.
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