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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

#421

Post by gambiting »

Krasnol wrote: post #222
moneytide1 wrote: post #174

Earlier quoted context omitted.

There's one in Finland: https://en.m.wikipedia.org/wiki/Onkalo_spent_nuclear_fuel_re... They have thought thousands of years ahead and set up many different types of warning signs and symbols in case a future civilization discovers it.

And than there is Asse: https://en.wikipedia.org/wiki/Asse_II_mine You just don't know. The time frame is too long. It's too long for natural causes and far too long for human civilisation. The earlier we stop producing this crap, the better.

Sure, but that's why I suggested deep borehole storage - there is no known geological process that can bring up material stored at 5km+ depth into the surface on any sort of human timescale. A mine, even at 700m depth, is just too shallow for long term storage.

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

#422

Post by SiempreViernes »

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…

What is the maximum external temperature the design can operate in? Can you build it in hot places to power air conditioning and things like that during the worst days?

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

#423

Post by manigandham »

pvaldes wrote: post #409
manigandham wrote: post #381

Earlier quoted context omitted.

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.

There is plenty of evidence - of no impact. As I said this has been extensively studied and there's so much radioactive material in the ocean that it makes no difference.

Also maybe you misunderstood the post because dumping in the ocean wasn't a real proposal. The point is that containment is solved, and indeed solved by very smart people. It's politics and general ignorance that has hampered nuclear power, not technology.

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

#424

Post by smilespray »

Cthulhu_ wrote: post #419
tgsovlerkhgsel wrote: post #163

Earlier quoted context omitted.

Around 600-700 kWh per cubic meter depending on temperature. The reactor outputs around 200 MW thermal. So if you have one of them in an olympic size swimming pool 50x25x2 meters, 2500 m^3, it'd need ~8 hours to evaporate the whole pool at full output. If you assume decay heat as 1% of regular output ( https://en.wikipedia.org/wiki/Decay_heat ), you'd need to add (or have stored) ~3 m^3 of water per hour, or slightly…

Makes me think; the water will not boil if the pressure goes up, was the Fukushima explosion caused by a hidden mechanism where if the water starts to evaporate, the steam can't go anywhere as to push the pressure up to keep it liquid?

That was a hydrogen explosion.

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

#425

Post by rkangel »

phkahler wrote: post #144
adammunich wrote: post #85

Earlier quoted context omitted.

It's really hard to comprehend just how much heat a reactor can make from decay alone. Like... boiling a hot tub in only a minute.

And so a pool of water is not enough because it will boil away. A continuous flow must be present that can not be interrupted.

It's not necessary as discussed elsewhere, but even if it was a concern simply build it near a river, below the water level and dig a connecting canal (that is normally closed off). In the very worst case just lift a sluice gate and the tank will remain topped up.

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

#426

Post by manigandham »

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.

No need to keep it contained, the oceans have billions of tons of dissolved radioactive material already. Adding more isn't going to change anything.

Dumping in the oceans isn't a serious proposal. I was pointing out that waste is not a huge problem.

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

#427

Post by pvaldes »

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.

The water in a glass can take a long time to evaporate, but if you put your fist inside the glass and press you will have a sudden loss of 2/3 of the water in seconds.

There are pools and pools and there are leaks and leaks. Anybody that has built an aquarium knows that a 80cm high design is much more complicated to made leak-proof than a 40cm high design holding the same water.

A shallow pool would not be enough to contain a small nuclear plant, so you need a non standard bigger pool. Higher the pool, higher the weight of water column, the force pressure against the walls will increase, and the leak will be much faster because the water weight in the upper level of the pool will force the water in the low levels to go out. If your leak is in the upper side of the pool will be a small self contained problem but if the bottom leaks is a different thing. As the bottom needs to support much more force against it and there is a weak area when walls meet bottom, is more probable to fail first.

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

#428

Post by michaelt »

kgabis wrote: post #402
legulere wrote: post #400

Earlier quoted context omitted.

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.

The kind of nuclear submarines governments are trying to raise and properly dispose of, because they're worried bioaccumulation will taint their fish stocks? [1]

[1] https://www.bbc.com/future/article/20200901-the-radioactive-...

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

#429

Post by mnw21cam »

ascar wrote: post #408
marshray wrote: post #67

Earlier quoted context omitted.

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 Amazo…

Please don't put it all in a "5m high storage facility the size of an American football field". Google for "nuclear favourable geometry" for why.

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

#430

Post by nix23 »

wukerplank wrote: post #411
nix23 wrote: post #405

Earlier quoted context omitted.

>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 ;)

I suppose earthquakes and other disasters happen (and possibly tilt the reactor) however Earth is shaped?

Sure, you are right but i see HN needs the ⸮ ....
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