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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

#511

Post by shadowprofile77 »

njarboe wrote: post #507
shadowprofile77 wrote: post #505

Earlier quoted context omitted.

Layman's question: I don't see how this small reactor is so unique or why it took so long to be developed for regulatory approval. The article claims it produces about 50MW of power with a planned 60MW version. Well, there are already very compact reactors in use on today's aircraft carriers (the A1B and A4W) that produce a much larger 500 to 700MW per module and are also relatively small (after all they fit on indiv…

The $1/2 billion they had to spend due to paperwork related to certification of the design. From an earlier comment[1] from a different thread about this approval quoting NuScale's press release: "NuScale spent over $500 million, with the backing of Fluor, and over 2 million labor hours to develop the information needed to prepare its DCA application" Military reactors don't have to go through this process and those…

In other words, the "impracticality" of compact, safe terrestrial reactor designs is almost entirely created by an immense mountain of bureaucratic hurdle that the military is excepted from? I can see the need for safety and careful documentation of contingencies but the scale of what you describe is simply dismaying.

Thank you for that answer and link. checking further now.

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

#512

Post by mikeyouse »

therealdrag0 wrote: post #508
mikeyouse wrote: post #44

Earlier quoted context omitted.

Wow. That’s substantially more expensive than I was expecting. It’s been years but we always assumed ~$0.08/KWh for on-site natural gas generated electricity on US based projects.

I wonder how much more would that be if the median carbon-tax proposal was added?

We did some calcs to that effect since we were operating in Australia, and they had a $25/ton carbon tax at the time. If my memory serves, it would increase natural gas costs by ~25%. So it'd likely still be right around $0.10/KWh.

Actually I take that back - our calcs were all based on ~$4/mmBTU gas but I just looked and gas prices have been below $3/mmBTU for years. So $0.08/KWh is probably a worst case even if we had a reasonable carbon tax.

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

#513

Post by Retric »

sergeykish wrote: post #468
Retric wrote: post #440

Earlier quoted context omitted.

What specifically is going to cause mass migrations in your mind, and on what time scale? Sea level rise on the order of 5 feet in 80 years is hardly going to make most countries uninhabitable. Over longer time scales will see much larger increases, but the yearly change is never projected to be that rapid. Water availability is a concern for farming and industry, but not really people. Desalination is cheap enough f…

As armchair academic I kind of understand you. People live in all sort of horrible conditions today - famine, malaria, diseases. As living person I ask myself what if my home was destroyed by flood? What if there is no water to grow food? What if person from the country which caused most of CO2 emissions [1] expects me to be contempt? Shouldn't I blow them up? Maybe all I need to commit is a good preacher. Last mass…

Supply disruptions occur with every war or crisis yet modern economies are extremely resilient. The trap is thinking the economy needs exactly what it’s getting rather than it being the result of a giant optimization problem on available resources. Just look at the US GDP drop from Covid vs the percentage of people staying home.

I also think that you are assigning agency to the general public in ways that are unlikely to hold up. Clearly groups could whip up hatred over global warming, but they can do that over just about anything. The root cause is almost never as important as the people guiding things and the goals being pushed.

As to [1] what’s interesting to me is the US emissions are currently about 1/2 of China’s and dropping fairly quickly while China’s are still expanding rapidly. Dropping US emissions will continue to help, but it’s currently less important than slowing how fast China’s increase. And thus someone aims the mob at a slightly different target.

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

#514

Post by RangerScience »

pvaldes wrote: post #302
RangerScience wrote: post #131

Thinking about the cooling pool: Could you just make an off-shore in-ocean "farm" of these?

> Could you just make an off-shore in-ocean "farm" Not! Ocean is inherently unstable!. The first serious storm would dislodge and damage the whole farm crashing one module against the other before to vomit them in the shore. Some modules just would dissapear. And then you have a humongous environmental damage and a really expensive rescue problem trying to clean the fragmented mess.

AFAIK, put em deep enough - which isn't that deep - and you're basically fine? It's why subs (AFAIK) DGAF about storms.

Mutual impact issue sounds pretty resolvable with a big steel frame and the like.

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

#515

Post by DuskStar »

tehabe wrote: post #412
john-shaffer wrote: post #170

Earlier quoted context omitted.

The sun also will burn out eventually, and every other star as well.

at that point the Earth will also be uninhabital and gone and if we found a new planet to live on, there will be another sun.

And at that point we'll have access to uranium from asteroids and other planets.

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

#516

Post by hansthehorse »

shadowprofile77 wrote: post #505
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…

Layman's question: I don't see how this small reactor is so unique or why it took so long to be developed for regulatory approval. The article claims it produces about 50MW of power with a planned 60MW version. Well, there are already very compact reactors in use on today's aircraft carriers (the A1B and A4W) that produce a much larger 500 to 700MW per module and are also relatively small (after all they fit on indiv…

Naval reactors use fuel that is enriched to weapons grade. I'm pretty sure we don't want that sitting around in towns all over America.

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

#517

Post by hansthehorse »

petre wrote: post #367
URSpider94 wrote: post #322

Earlier quoted context omitted.

I haven't had time to read all of the info, but I get the impression that this is still a pressurized water reactor, just on a smaller scale. It will fail in pretty much the same way as current reactors like Fukushima and Chernobyl. I believe that the point is that the pool provides an extra level of failsafe against coolant loss, and additionally that the substantially smaller size of the core limits the amount of h…

Fukushima is a BWR design using water moderator, closed with a lid bolted on a flange. It uses two pumps. Chernobyl is a RBMK design with graphite moderator and a highly positive void coefficient. This reactor is a much smaller PWR with a double containment and natural circulation, without these failure modes.

In a standard commercial pwr the containment building is a steel shell surrounding the entire system, then there is a void of varying width then that large cement building that you can see when driving by. That building is called the shield building.

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

#518

Post by hansthehorse »

p1mrx wrote: post #401
newacct583 wrote: post #115

Earlier quoted context omitted.

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?

Once an attacker is inside the plant, with just some Wiki knowledge, any plant is as good as melted down. It's a much better plan to simply drain the spent fuel pool.

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

#519

Post by Klinky »

roenxi wrote: post #510
Klinky wrote: post #498

Earlier quoted context omitted.

Solar does not have the special handling and proliferation issues that nuclear waste does. Disposing of or recycling broken solar panels is significantly less complicated than spent nuclear fuel and waste byproducts. Recycling and disposal does need consideration for renewables, as well as nuclear. You cannot just say "Well no one is looking into it for solar, so nuclear should get a free pass too!", especially when…

> Solar does not have the special handling and proliferation issues that nuclear waste does. That is also what I'd expect to see if people aren't taking the issues seriously, so it isn't really evidence of anything. > You cannot just say "Well no one is looking into it for solar, so nuclear should get a free pass too!" Sure I can. The evidence to me suggests that, for equivalent amounts of effort and adjusting for th…

Are you suggesting I am not taking it seriously, while also saying "Sure I can" when it comes to ignoring nuclear waste storage issues? Waste amounts are "tiny", and "bury it in a hole somewhere", ignoring time and cost components. Hard to take you seriously.

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

#520

Post by p1mrx »

hansthehorse wrote: post #518
p1mrx wrote: post #401

Earlier quoted context omitted.

> 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?

Once an attacker is inside the plant, with just some Wiki knowledge, any plant is as good as melted down. It's a much better plan to simply drain the spent fuel pool.

I think it takes a bit more than Wiki knowledge to drain an in-ground pool... you would need to keep a large pump running for hours, under duress.
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