Small nuclear reactors: tiny NuScale reactor gets safety approval • Hacker News Board

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

#391

Post by jabl » Fri, Sep 04, 2020, 6:32 AM UTC

dodobirdlord wrote: post #375

Klinky wrote: post #350

Earlier quoted context omitted.

France's program is effectively government run, and heavily in debt. I cannot find indication that reprocessing is profitable in the short term, but obviously it has advantages in the long term by reducing waste. That said it does not eliminate the waste issue, nor is France buying up spent waste from neighbors to cash in, nor are they dumping it in the ocean or children's playgrounds (it is still extremely harmful).…

A nuclear waste reprocessing program should be 100% government run, or at least government controlled, because part of the process involves refining the plutonium that could then be used to make nuclear weapons. This is why most countries don't reprocess their spent fuel, it's considered a nuclear weapon proliferation risk to reprocess, and the downside of accumulating spent fuel waste is considered minor in comparis…

There are reprocessing methods that are less sensitive to proliferation, such as pyroprocessing where you never have pure plutonium.

Still, there are risks, and I agree it makes sense for reprocessing facilities to be government controlled.

That being said, without also deploying breeder reactors at scale there's not a lot of benefit from reprocessing.

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

#392

Post by tandr » Fri, Sep 04, 2020, 6:34 AM UTC

thallium205 wrote: post #361

marshray wrote: post #67

Earlier quoted context omitted.

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

SpaceX rocket to the sun.

Thank you. I don't get why this is not considered as an option anywhere.

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

#393

Post by gambiting » Fri, Sep 04, 2020, 7:00 AM UTC

zmmmmm wrote: post #335

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…

> It's not coming back no matter what If you can drill down to put it in, can't you also drill down (or use the same hole) to get it out?

Well, yes, technically. I meant more that the waste won't come back on its own, through tectonic movements, earthquakes, meteor strikes or pretty much any other natural process known to man. You could drill down to retrieve it, but then it's a very specific thing serving one specific purpose. It's not like mine repositories, where they are at a much shallower depth and could be entered "easily" from the surface.

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

#394

Post by drran » Fri, Sep 04, 2020, 7:04 AM UTC

throwaway0a5e wrote: post #270

shortandsweet wrote: post #161

Earlier quoted context omitted.

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...

>but not spent fuel pools. Everyone misses things Everyone who remembers the post 9/11 "but what if the terrorists attack X" pandemonium knows that spent fuel pools are outside the containment building. That was one of the scenarios that got paraded around to maximize FUD.

I was involved in closing of case, when terrorists wanted to create dirty bomb and throw it at Ukraine. S*it happens.

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

#395

Post by dmix » Fri, Sep 04, 2020, 7:04 AM UTC

PeterStuer wrote: post #377

Fwiw, any nuclear reactor design in history was sold as 100% safe. In reality, shit happen. Contractors use subspec material, things on the building site get overlooked and inspectors miss things or get told to look away, But hey, I'm sure, this time, it will be different. 100%.

What if they build this on a floating oil rig type situation and fallback dumps it into an ocean fed pool (like a box with gaps for ocean water going down 100ft) far enough off the coast to have power lines but easy enough to recover?

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

#396

Post by p1mrx » Fri, Sep 04, 2020, 7:09 AM UTC

dheera wrote: post #329

patmorgan23 wrote: post #313

Earlier quoted context omitted.

You'd still need a heat exchanger at some point, and you want a lot of surface area and thin walls for that.

Random thought experiment -- why not just drop it in the middle of a lifeless desert, forget about heat exchangers, and just let it slowly melt its way down through the crust of the earth? Assuming it went straight down and into the mantle, it would probably not impact the ecosystem.

Even in a desert, you'll cross the water table before reaching the mantle. And people prefer to consume electricity in hospitable locations.

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

#397

Post by sriku » Fri, Sep 04, 2020, 7:21 AM UTC

I was looking for a reference to the physical size of the reactor and couldn't find it. The sites only say "smaller". Any links with size info and requirements for containing infrastructure?

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

#398

Post by p1mrx » Fri, Sep 04, 2020, 7:22 AM UTC

ses1984 wrote: post #315

ClumsyPilot wrote: post #300

Earlier quoted context omitted.

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.

I'm not sure it's that simple.

It's literally a big hole with water in it; what are you unsure about?

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

#399

Post by jabl » Fri, Sep 04, 2020, 7:23 AM UTC

adrianmonk wrote: post #151

stickfigure wrote: post #111

Earlier quoted context omitted.

Nukes are slow from a cold start but they can throttle up and down with load. https://en.wikipedia.org/wiki/Load_following_power_plant#Nuc... Modern nuclear plants with light water reactors are designed to have maneuvering capabilities in the 30-100% range with 5%/minute slope.

Wow, that's pretty fast. So 12 minutes worst case. TIL. Still, I wonder if the economics don't favor running near 100%. You've already paid the high up-front cost of the equipment, and fuel costs are low, so I assume you're better off selling excess power when possible.

Of course. Though with increasing deployment of intermittent sources like wind and solar, occasionally the wholesale price can drop lower than the marginal cost of the nuclear plant (or even negative, if said power sources receive production subsidies regardless of the wholesale price), in which case it makes sense to throttle down.

Future grids with more intermittent renewables will have increasingly volatile prices, but not necessarily lower on average. So generators that can produce during high price periods (e.g. if wind and solar aren't producing much) can make a lot of money then, compensating for less income during low price periods.

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

#400

Post by legulere » Fri, Sep 04, 2020, 7:30 AM UTC

manigandham wrote: post #114

marshray wrote: post #67

Earlier 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…

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.