Earlier quoted context omitted.
>> What happens when the ultimate heat sink is lost? What's an example event where the ultimate heat sink might be lost?
No expert, but if it's a pool of water then an earthquake might cause a leak?
evaporation?
Small nuclear reactors: tiny NuScale reactor gets safety approval
141–150 of 554 posts
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#142Earlier 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 think the modern (3rd generation?) Reactors have been designed to use much more of the fuel, leaving considerably less as waste, and actually potentially using preciously used spent fuel as fuel, which of course would be cleanup. The problem is approval and building of anything new.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#143Earlier quoted context omitted.
If only a method for permanent disposal of nuclear waste actually existed.
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…
Are you trying to piss off Namor?
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#144Here 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…
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.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#145Earlier quoted context omitted.
Unfortunately that doesn't quite solve the problem of getting waste from reactor to storage site.
Besides the obvious NIMBY problems, are there any problems with sealed casks transported by train?
No. These things are tested to a VERY high standard.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#146This 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.
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.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#147fyi, OSU college has a 1-megawatt research reactor. https://www.oregon.gov/energy/facilities-safety/facilities/P... https://www.corvallisadvocate.com/2012/got-nuke-state-of-the...
I just recently watched this video/tour of MIT's reactor, pretty interesting.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#148Earlier quoted context omitted.
> Nuclear reactors take ages to ramp up and down. Naval reactors are apparently very fast in this regard, so it's evidently not an inherent property of nuclear power. (The USN also has an unparalleled record of safely operating reactors; more that 5,000 reactor-years clocked without major incident.)
Does it count that a Navy man was killed at SL-1? https://en.wikipedia.org/wiki/SL-1 https://www.findagrave.com/memorial/67718734/richard-carlton...
SL-1 was an Army reactor, so I would say it doesn't count. I'd also not count the USS Thresher or the USS Scorpion, since reactor accidents weren't the reason those sank.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#149Earlier quoted context omitted.
you forgot to mention that those 23 m high containment vessels are places in in a pool which of course have to be much bigger than that: "The reactor and containment vessel operate inside a water-filled pool that is built below grade." We'll see of this is in any way or form sustainable, especially since uranium is also a finite ressource.
There's ~4 billion tons of uranium dissolved in seawater, too. Which is enough for a millenia or three - if we used it for all of our power needs.
That is not really the point, it doesn't matter if there is 4 or 40 or 400 billion tons of uranium, the point is that it is finite. At some point, there is none, or better there is no more usable ressources available. This can be shifted with technology and better knowledge but it is still finite. And that is all the point I wanted to make.
Re: Small nuclear reactors: tiny NuScale reactor gets safety approval
#150Earlier 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.
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 in their design.