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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

#451

Post by TheOtherHobbes »

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…

I'd be more concerned about possible coolant loss and/or valve failures because of corrosion.

https://www.sciencedirect.com/science/article/pii/B978184569...

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

#452

Post by antepodius »

jacobwilliamroy wrote: post #325
bluejellybean wrote: post #306

Earlier quoted context omitted.

Absolutely, why not? As long as the waste dealer is offering a deal that is satisfactory for me as the landowner/waste site, I would happily store said waste. Your question is a bit absurd; nobody is suggesting to keep it inside of someone's home. Should an individual not be allowed to make rational decisions about their land and property? If I owned 20 square miles in the desert, why shouldn't I be allowed to lease…

In my personal philosophy, as a landowner you are responsible not only for yourself and your neighbors, but also for the next 7 generations of people who will be using that space after you. So to me, no you have no right. But that's just my own opinion.

I suppose you don't have any right to put solar panels on your home, then, given that they're full of chemical waste that remains dangerous indefinitely.

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

#453

Post by sandworm101 »

crowbahr wrote: post #448
sandworm101 wrote: post #446

Earlier quoted context omitted.

So it requires gravity. It may seem trivial, but how would this thing react if suddenly not mounted vertically, say if it got knocked onto its side while running? Would coolant still flow as planned?

Anything that knocks a fully functional multiple thousands of tonnes of concrete, steel, water and fissile material onto it's side was already going to fuck up your day. As far as I'm aware we've never had a nuclear reactor go sideways, and it's kinda ludicrous to even ask. It's one of the most massive structures, built on bedrock because it's too heavy to be built on anything else, and even these "small" reactors wi…

They are vertical cylinders to be suspended vertically in a pool of water, not massive squat objects sitting on bedrock. They are thin and relatively top-heavy. It is not ludicrous to ask what could happen should they not remain as vertical as designed.

From a planning perspective, if verticality is a requirement then that verticality has to be protected as strongly as any other aspect. Any attachment or mounting points that maintain verticality must therefore be earthquake proof. If, as in the pictures, these reactors are held in place from the top, horizontal shaking from even a small earthquake would put massive strain on that joint. It isn't just the long/thin/heavy reactor but all the water sloshing around too. A super-strong joint and maybe something important bends/breaks under load? A flexible joint to allow the reactor to sway? Sway how much? What happens at the travel limit of the joint? Can we risk the reactor contracting its neighbours? These are not trivial engineering questions.

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

#454

Post by grandinj »

I don't know why they are bothering to try and build this in the US. Between the insane regulations, the anti-nuclear lobby, and the NIMBYs, they don't stand a chance.

Surely they would have a much easier time selling things like that elsewhere? Growing nations would probably love reliable power that could be plonked down off a ship and added to incrementally.

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

#455

Post by yohannparis »

SiempreViernes wrote: post #422
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…

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?

Those reactors are small compare to usual one, but they still operate in a power plant like a gas or coal one. It's not a home or neighbourhood nuclear reactor.

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

#456

Post by roenxi »

kelnos wrote: post #388
godelski wrote: post #240

Earlier quoted context omitted.

> 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…

> The other reason we don't do it is that it is just cheaper to buy more Uranium than setup reprocessing plants Is it cheaper to buy more Uranium and deal with the so-far-and-growing half-trillion dollar cleanup liability than to set up and operate reprocessing plants? Of course I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it.

> I wouldn't be surprised if that liability is considered "tomorrow's problem", so no one in power cares about it.

I was talking to an environmental scientist that other day who was lamenting that the liability for solar panel waste was being treated as "tomorrow's problem", and no one in power cares about it.

If we factor in the tomorrow problem nuclear looks even better, because we have a chance of being able to deal with it. Nobody attempts to solve the decommissioning problems of most waste, there is too much of it so we just dump it in landfill and hope there isn't anything too nasty in it. There is no plan at all to deal with it beyond 100 years or so, and it doesn't get less toxic over time.

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

#457

Post by HPsquared »

petre wrote: post #384
thekyle wrote: post #158

Earlier quoted context omitted.

Wow. How do they design them to withstand a strike from a 747? That seems really difficult.

Yes. A NRC requirement for utility scale reactors after 9/11. One wonders why nuclear reactors are so expensive.

It's a good reason to design reactors to be as small as possible, with a small containment building. Much easier to build.

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

#458

Post by roenxi »

moneytide1 wrote: post #174
gambiting wrote: post #118

Earlier quoted context omitted.

Another option which is completely safe and permanent* is drilling a borehole few km down and dumping the waste there. It's not coming back no matter what. The research done into it shows that "only" 800 boreholes would be required to store literally all nuclear waste ever produced. https://en.wikipedia.org/wiki/Deep_borehole_disposal *to a point where it was actually brought up as a negative, because if we ever want…

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.

> They have thought thousands of years ahead

That level of stupid theatrics really annoys me. If society has regressed then it will be a godsend to rediscover nuclear power. If society has advanced this is like the Romans trying to anticipate modern problems.

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

#459

Post by revax »

godelski wrote: post #331
natmaka wrote: post #320

Earlier quoted context omitted.

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…

I'm unsure what you are suggesting here, so I want to be extra clear about the French policy and current state of affairs. As in stands, France has one of the lowest CO2 emissions per capita[0][1]. No one is saying that we should _only_ use nuclear. Not diversifying your energy portfolio is a terrible idea. France is trying to reduce its dependence upon nuclear (which is a good idea) and replace its fossil fuel infra…

>Nuclear serves as a baseload and backbone

Not in France, the nuclear plants here can do some load following (to some extent).

>You will not find pro-nuclear supporters upset with France's decision to reduce their dependence on nuclear. In fact you will often find support.

I cannot agree here, there is a growing movement mainly lead by Jean-Marc Jancovici deploring the shutdown of safe and profitable nuclear power plant.

The main argument being when you already have a low carbon energy production, the money invested in the construction of new renewables power plant will better used in home insulation subsidies or subsidies for a heat pump.

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

#460

Post by revax »

valuearb wrote: post #353
manfredo wrote: post #109

Earlier quoted context omitted.

The last ice age occurred gradually over the span of millennia. Anthropic climate change is occurring in an instant by comparison. Not to mention, humanity survived by mass migration, something that's a lot harder for integrated global economies to do. Few believe humanity is going to go extinct. But extinction of industrialized civilization is a more real concern. And the collapse of industrialized civilization will…

Humans aren’t at risk from climate change, it’s all the other species without our powers of quick adaption.

Even for Humans, some regions of the world will be simply to hot to be continuated habited.
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