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Small nuclear reactors: tiny NuScale reactor gets safety approval

popularmechanics.com

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

#201

Post by entropicdrifter »

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.

I'd be willing to bet there are some significant thermal efficiency losses at 100% that would push you down closer to (made up number incoming) 80% at idle

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

#202

Post by rstupek »

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…

Or use the waste (which is still highly energetic) in a traveling wave reactor a la terrapower?

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

#203

Post by tpxl »

phkahler wrote: post #179
sitharus wrote: post #160

Earlier quoted context omitted.

You need a sufficiently large reserve to allow the reactor to cool, not an infinite supply. Reactors can be shut down and in this case the pool is sized to absorb all decay heat from the shutdown, plus a significant safety margin.

Great, and ideally gravity can be used to move it. Remember, at Fukushima power to the pumps was lost.

Afaik some reactor designs drop the core in a tank below in case of emergency.

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

#204

Post by baybal2 »

liability wrote: post #91
adrianmonk wrote: post #39

Earlier quoted context omitted.

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. 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.)

> Naval reactors are apparently very fast in this regard, so it's evidently not an inherent property of nuclear power.

Ramping up is easy, ramping down... not so much.

It's not as much of an issue if you swim in your coolant, hence naval reactors are unique in being able to ramp both up, and down quickly.

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

#205

Post by briffle »

Klinky wrote: post #166
dodobirdlord wrote: post #88

Earlier quoted context omitted.

The world is filled with naturally occurring phenomena far more dangerous than a big pile of low-grade nuclear waste. The really dangerous stuff ceases to exist after a few decades of sitting in a cooling pond, and then what’s left has such a long half life that it’s not particularly threatening. Water is an incredible radiation dampener, and the ocean is already chock full of dissolved uranium. The only reason we do…

You're underplaying the danger and overplaying the value. Who exactly is investing in this "green gold"? If it's so valuable why does no one actually want it, and why is the DoE stuck with half a trillion liability?

They are stuck with the liability, because President Carter Banned reprocessing of Uranium in 1977, and nobody has changed it. If we reprocessed Uranium, we would end up with much less low level waste, and some very, very small amounts of more radioactive materials (that can be burned in some other types of reactors)

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

#206

Post by evilos »

rubber_duck wrote: post #34
nickik wrote: post #27

As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all that great of an idea. Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. I really believe we should be a nuclear society by now, and that regulations both around react…

>Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. You mean they lose operational efficiency ? Economies of scale come from the ability to mass produce. You forgot to mention the largest differentiator - eliminates the possibility of a global cat…

If you can pump out standardized large scale reactors like France did, then they are way more efficient than these smaller reactors.

The problem of course is that takes a large government to mandate a huge public project, which is not really likely these days. The advantage of these small reactors for now is that they hopefully prevent expensive,bloated, one-off site designs that go over budget and miss their schedules.

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

#207

Post by asdfman123 »

phkahler wrote: post #179
sitharus wrote: post #160

Earlier quoted context omitted.

You need a sufficiently large reserve to allow the reactor to cool, not an infinite supply. Reactors can be shut down and in this case the pool is sized to absorb all decay heat from the shutdown, plus a significant safety margin.

Great, and ideally gravity can be used to move it. Remember, at Fukushima power to the pumps was lost.

The article states the whole reactor will be submerged in a pool of water, making it passively safe.

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

#208

Post by nickik »

marshray wrote: post #93
nickik wrote: post #70

Earlier quoted context omitted.

It disingenous of you to argue that all DoE cost from the last 60 years have any implication on a modern nuclear site build. When nuclear started they had no idea how to do things and had to do a lot of things very fast. The waste majority of those cost are not because of civilian nuclear reactor, but rather creation of nuclear weapons. Site cleanup cost are a factor, but not a huge one considering a site can be acti…

Perhaps you'd like to link to some figures for the cost of permanent disposal of commercial waste? Or were you just planning to let the grandkids deal with that?

All US reactors already pay a fee that takes care of waste. This fee accumulates in government accounts because government because political deadlock. Since start of operations tons and tons of money has been gathered threw this process. Its completely because of government failure that no progress have been made. The fee was designed to be enough to handle the waste and it would be.

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

#209

Post by nickik »

rubber_duck wrote: post #34
nickik wrote: post #27

As a huge fan of nuclear power, I never felt like NuScale style 'SMR' were all that great of an idea. Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. I really believe we should be a nuclear society by now, and that regulations both around react…

>Yes, it gains you some of the economics of factory construction and that you can start small and scale a location, but on the other side you lose that again because you lose the economics of scale that traditional PWR gets. You mean they lose operational efficiency ? Economies of scale come from the ability to mass produce. You forgot to mention the largest differentiator - eliminates the possibility of a global cat…

Economics of scale are the reasons modern Gen3+ reactors are so huge.

From AP1000 wikipedia:

> The design traces its history to the System 80 design, which was produced in various locations around the world. Further development of the System 80 initially led to the AP600 concept, with a smaller 600 to 700 MWe output, but this saw limited interest. In order to compete with other designs that were scaling up in size in order to improve capital costs, the design re-emerged as the AP1000 and found a number of design wins at this larger size.

So modern PWR are usually build with 1GWe one location one reactor, huge economics of scale in terms of the size of the power plant. A AP1000 is not much bigger then an AP600.

> You forgot to mention the largest differentiator - eliminates the possibility of a global catastrophe.

I disagree. First of all, I think the possibility of a global catastrophe with a traditional PWR are already incredibly small, and when talking a modern build like an AP1000 the NuScale doesn't have that much better safety characteristics.

PWR are inherently problematic and require tons and tons of complex engineering to make them save and the error potential in such a solution are always there.

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

#210

Post by asdfman123 »

omginternets wrote: post #128
marshray wrote: post #67

Earlier quoted context omitted.

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

If only a method for permanent disposal of carbon dioxide emissions from gas plants actually existed.

Lots of methods exist, but they're too expensive or don't scale well.
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