Small Modular Nuclear Reactors Overcome Existing Barriers to Nuclear | Hacker News Reader

Small Modular Nuclear Reactors Overcome Existing Barriers to Nuclear

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85 pointsOsiris3084 comments

This is not really about micro reactors, but about making the monolith power plant more like a microservice modular thing. So that you can potentially prevent decomissioning after 40 to 60 years and keep it operating much longer.

The downside of nuclear power still remains though: - still high upfront costs (maybe lower that monolith plants, but still freaking high) - poisonous and radioactive fission products that are hard to deal with - perverse incentives between economic efficiency and safety (did I mention that a couple of those babies [1] here would have prevented the fukushima disaster)

[1]: http://us.areva.com/EN/home-1495/new-challenges-proven-solut...

To be fair, the byproducts are not something we're unaware of how to manage, we're just socially and politically unwilling to do it. Likewise, we know how to design and maintain much safer and more efficient reactors than anything we currently have running, but we lack the social and political will to make the change.

Besides, we like to pretend that burning coal isn't killing millions of us around the world, decade in, decade out. Focusing on the real human cost of when nuclear goes wrong, vs. when coal goes right makes it an easy choice.

Per kilowatt, nuclear energy is by far the safest. People fall off wind and solar installations all the time. Hydro fails catastrophically.

How can you say that without being cynic when it made big parts of Japan uninhabitable for centuries if not thousands of years?

Do you have quantitative information about that? I was always wondering how big is Fukushima's nuclear incident zone (in km^2) today. How much bigger is it compared to coal waste ponds / landfills, or hydroelectric dam which provides the same amount of power?

The problem with coal as well, is that the effect of its pollution is known to contribute to many deaths a year, especially in the elderly, people with compromised cardiopulmonary systems, and of course, the asthmatic. It's not like a nuclear disaster though, where someone comes in "radioactive" with coal. The best we can do is explain the statistical link.

When nuclear goes wrong, it's much less lethal, but so much more easy to recognize and very dramatic. Then again, we live in a world of people obsessed with shark attacks and winning the lottery, but who drive around in cars all day.

The exclusion zone is 20km, so the area will be around 600 km^2. Compare that to Lake Mead, which is 640 km^2 and runs a power station with half the installed capacity of Fukushima Daiichi.

A circle of 20km is 1200 km^2.

In this case, only half the circle was over land, but the evacuation zone also extended about 40km downwind, based on the amount of radiation, so the original exclusion zone was also about 1200 km^2.

Since then, part of the exclusion has been lifted: I think in this map, the green areas are places which are no longer restricted. The yellow areas can be visited with a permit, but you are not allowed to live in them or stay over night. The pink area is the "difficult to return" zone, I think the government treats this as a total loss and reimburses house owners for the full value of their property.

http://userdisk.webry.biglobe.ne.jp/001/285/53/N000/000/009/...

From counting pixels in the picture, it seems the yellow+pink area is 670 km^2, and the pink area is 330 km^2.

The failure of the Banqiao Dam in China in 1975 killed 171,000 people; 11,000,000 people lost their homes. This is many orders of magnitude higher than the casualties and damages directly attributed to the failure of Fukushima Daiichi nuclear power plant.

Furthermore, Fukushima Daiichi was an old design (more than a decade older than Chernobyl nº4 reactor) whereas modern designs are much more safe.

Fukushima Daiichi was also subjected to a historically significant natural disaster, it wasn't exactly an "everyday" or even "every century" event.

And the area around the reactor isn't uninhabitable, it's just illegal to live there at the moment.

Yes. What is funny is that some of my countrymen, who lived in Japan as expats, left the area because of radiation, and came back home, where the natural background radiation is higher than in the evacuated Fukushima area.

From what I can tell, Banqiao Dam was dual-purpose: it was intended for flood control as well as power generation. If China had sourced power from a nuclear plant, the dam would likely still have failed and killed hundreds of thousands of people, we just wouldn't be able to attribute those deaths to hydroelectric power.

Furthermore, modern nuclear power plants may be safe but they aren't exactly economically viable, which is why nuclear operators are so keen on extending the operation of existing plants of the same design as Fukushima Daiichi. Also, I'm pretty sure the official position on Fukushima was that it was safe, right up until it wasn't.

The fact remains that hydro power requires storing the potential energy of a very large amount of water. This is inherently a danger for the population living downstream. I certainly would prefer to live in the vicinity of a nuclear power plant rather than in the floodpath of a large dam.

Not to mention that if something goes wrong with a plant, you'll probably have time to evacuate. If a dam fails catastrophically, you'll probably first know when you feel the ground shaking, and that will be too late for you.

I don't know about Solar and wind being inherently less safe, in fact I'd disagree with that. The issue though, is that we still can't rely on them to power our entire grid. Hydro though, even without failure, seems to have a pretty undesirable environmental impact. Nuclear has to go catastrophically wrong for that to be the case.

> Hydro though, even without failure, seems to have a pretty undesirable environmental impact. Nuclear has to go catastrophically wrong for that to be the case.

Arguably, the Chernobyl disaster was an environmental boon by forcing humans out of a region and creating a de facto nature preserve.

For residential installs, solar systems go up on roofs, a few kilowatts at a time. The main risk is to the installers (they fall off). Little capacity per roof, every roof different, every fall a potential hazard = higher risk per kilowatt than you might think..

I suppose so, but it's a risk that can be managed with existing technology, and without spending insane amounts of money.

> The main risk is to the installers (they fall off).

Huge NO. The biggest risk is for firefighters if any part of the PV panel or the technology or the roof itself catch fire!

The DC side can easily pack in a couple hundred volts DC with double-digit amperages. And you can't turn it off unless the sun goes dark... not to mention that it's hard for firefighters to fight a fire if the whole roof is PV-panel-filled and something in the roof is burning.

People fall off wind and solar installations all the time.

But our society has always just shrugged its shoulders at this cost, so long as its paid by the working class. (In Texas, it's the lowest very rungs of the working class that get sent up radio towers.) It's different when the damage directly impacts homes, particularly those of white collar workers.

Sounds a bit like a chip on the shoulder when, in this context, you talk about radio towers, which aren't windmills or solar plants (although yes, accidents happen also there).

Also applies to coal miners. There are still a lot of fairly hazardous jobs in our society that our society isn't all that concerned about the workers being fully covered/compensated.

And people don't fall off nuclear installations as well? Death is tragic in all cases, but are death rates of workers in installations worse for solar installations? I can see it in wind installations, but are accidental rates in solar installations worse than those in the installation of nuclear plants?

Or radio masts, cell towers, smokestacks, etc. It's a known risk of working up on a tall structure, but it's also a risk that's understood, and managed with safety equipment and best practices. We don't seem to compose a dirge for every tree that gets trimmed around a utility pole either.

So what is holding back the safer/efficient reactors? Certification funding or proof of concept that leads to industry acceptance and federal funding?

Mostly politics. At every level, there is resistance, and motivation for politicians in congress (especially senators) to take a strong pro-coal, NIBMY to Nuclear stance. Any senator who accepts a disposal site, or new reactor site in their state is putting their career in the line. The kind of people who do that, tend not to become or stay senators.

The end result is that we're just sitting it out, because we've made it prohibitively expensive (in terms of licensing, and in terms of political capital).

Popular support. Legacy of Cold War era anti nuke propaganda and ridiculous portrayal of reactors and nuclear waste in fiction have lead to a skewed public perception on which politicians don't want to get burnt. Fukushima happened. Paperwork gets expensive. Active failsafe systems several layers deep complicate construction of plants. All of this loops back onto corporations and public institutions not wanting to invest into research.

I think nuclear is a technology that is beyond what the current human society can support - we really are not ready for the technology until we deal with uneducated masses, fundamentalism, techno-literacy etc

"The masses are too uneducated for nuclear" would be a lot more compelling an argument if those who are putatively "the educated" weren't quite against it too. It's not poor uneducated people filing lawsuits against every nuclear reactor every step of the way, and unless you mean "environmental fundamentalist" (which isn't out of the question) it's not any other sort of fundamentalist I can think of either.

Some people play the game of life cooperatively, by trying to help each other and make the world a better place for everyone. But there's also lot of those who play it competitively - who don't mind abusing the system and fucking everyone else over as long as they get what they want for themselves and those close to them. You can see plenty of the latter type among many educated people "filling lawsuits against every nuclear reactor every step of the way", along with many other things. The problem isn't with those on the other side of the issue who are honestly opposing it; the problem is with people on both sides who don't care about subject matter at all, but only about how to profit from it.

In my experience American society is organized around the belief that people can be left to pursue their own goals without everything falling apart. While there will still be corruption and selfishness, the government and culture work together to make sure this problem is, if not much less serious than in other kinds of societies, at least not more serious either.

It sounds like you are saying this isn't good enough, and that you would be against any powerful new technology until we can fix these problems. Until the fabled Eschaton/Utopia/perfect society arrives, basically.

I think this is a terribly misguided attitude. Cheap and plentiful power will save and help a lot more people than those hurt by accidents. Especially taking into account the amazing safety science and engineering that goes into this particular technology, and its amazing safety record apart from Chernobyl (you know, that graphite-moderated reactor with no concept of passive safety).

You misunderstood me; maybe my comment wasn't written clearly enough. Personally, I'm very much pro-nuclear for very much the reasons you articulated. I definitely don't think we need to stop good ideas because of social problems. I merely wanted to point them out - that nuclear energy (and many other things as well) is being blocked not because some people are wrong, but because some people don't care about it at all, but use it as a way to make a profit.

OK it seems like I had your point pretty much backwards, whoops.

No need for fancy chemical whatsis, all Fukushima needed to avoid disaster was a taller wall, or for the generators to be placed on the roof instead of in the basement.

This is strange. There is no "containment vessel". That's the reactor pressure vessel. Usually, there's an outer containment vessel as well. Chernobyl didn't have one at all, which is why that was such a disaster. Fukishima's reactors had ones that were too small and didn't have enough expansion volume to diffuse the pressure after loss of coolant. There's a design assumption here that there will never be a meltdown.

A containment vessel at Chernobyl would have been useless. The Chernobyl disaster was a combination of poor reactor design leading to dangerous reactor physics, poor safety systems, poorly-trained staff, and an dangerous and unnecessary "experiment" being performed on the reactor (i.e. operating it in a dangerous regime). No containment building could have been strong enough to contain the explosion. The RBMK is a particularly bad design of reactor.

> dangerous and unnecessary "experiment"

We always hear about how they were running the reactor in a dangerous mode to run the experiment, but the nature of that experiment is rarely mentioned. The experiment itself is the craziest part!

The experiment was a test of a new cooling system feature. The RBMK's suicidally stupid design had a positive void coefficient of reactivity[1]. Coolant voids increased reactor activity. The operators new this; they had backup diesel pumps that would take over from the electric pumps if power wasn't available. They also knew that it would take some time[2] for the backup pumps to reach full speed, which was not fast enough.

So someone had the "clever" idea to modify the electric pumps so they would continue to spin freely when they lost power, so their remaining kinetic energy could continue pumping coolant at a rapidly falling rate. The hope was that there would be sufficient kinetic energy to keep the reactors from voiding. The experiment was basically a bad hack to work around several serious design problems.

The experiment shouldn't have existed. Everything about the coolant situation should have been a reason to decommission the reactor. The experiment itself is evidence that someone knew about the positive void coefficient problem, or they wouldn't have tried such a crazy workaround. Yes, a lot of the staff was poorly trained, but someone knowledgeable about reactors decided they couldn't afford even a few seconds[2] without coolant.

[1] https://en.wikipedia.org/wiki/Void_coefficient

[2] like 50 seconds? if I remember correctly?

A positive void coefficient doesn't have to be suicidal or stupid, it just was in that design. See: CANDU

CANDU has a very small positive void coefficient.

I didn't say anything about a large void coefficient, and I pointed to CANDU as an example of a reasonable beta, responsibly managed.

> had a positive void coefficient of reactivity

Had and still does. There are 11 RBMK blocks still operating.

LFTR should be implemented like this: modules that can be decommissioned on a scheduled basis so that the transmuted parts of the container can be recycled/extracted.

The article doesn't seem to mention what type of reactor this is. Are these still gen-III boiling water reactors, or is this a gen-IV type reactor?

The design illustrates fuel rods; so not a thorium reactor (if that's what you mean by Gen4).

Doesn't some gen-IV designs boil water too?

Nobody designs new boiling water reactors these days. Reactors efficiency increase with temperature, that is why pressurized water is the name of the game - as it can have a much higher boiling point.

The higher temperature = better reasoning is also the reason why there is such a hype train going for reactor designs based on molten salts.

Needless to say a higher temperature also puts more strain on any material and makes safe operation generally harder.

One of the things that I don't get is that there a lot of cool fission designs that are arguably only hampered by the state of the art in molten-salt plumbing, but the only fusion design with mainstream support requires molten lithium plumbing for breeding tritium and heat exchange, along with a few other things that are still a touch experimental. Hash out the molten salt plumbing for the fission reactors since it appears strictly a subset of the fusion problems.

No, its not a subset of fusion problems. Very different problems:

Molten salt fission problem = dealing with vast quantities of a highly chemically active salt touching our plumbing directly over 40 to 60 years.

Fusion problem = containment of a small quantity by a magnetic field.

Fusion also has the "dealing with vast quantities of a highly chemically active salt touching our plumbing directly over 40 to 60 years." Nobody talks about it because the magnetic containment problem is harder.

You can't use water like most fission designs?

Some fusion designs in theory would burn deuterium-tritium. Typical way to produce tritium is from lithium. When lithium absorbs a neutron it fissions into tritium + helium. Potential designs for fusion reactors then have a way of exposing lithium to the neutron flux from the reactor.

These smaller modules would be ideal for that. As the plumbing wears out, replace the module, and recycle the old module, make another one.

Smooths the scaling, production process outlays, gives opportunity for continuous improvement in the module manufacture and efficiency

That's great. You know how expensive it is to get rid of radiactive material. It this comes true the big power plants can just dump the waste into the river and say "It wasn't me".

I would not want to live next to such a thing.

https://en.wikipedia.org/wiki/Deep_geological_repository

And?

There is no repository in the world available, that is either guaranteed to be secure for thousands of years of accepted by the population.

Also putting it in the earth has one huge disadvantage: You cannot get it back if something goes wrong.

I can recommend this documentation about the waste disposal problem http://www.imdb.com/title/tt2979302/

There is no repository in the world available, that is either guaranteed to be secure for thousands of years of accepted by the population.

But we would have no need for "thousands of years" if the development of nuclear reactors is allowed to advance. Fast breeder reactors can use our current "waste" as fuel, leaving only stable and short-halflife isotopes as waste.

Let’s look at the German Asse II and Schacht Konrad.

We deposited lots of nuclear waste, and years later discovered it was leaking into the tap water.

Now we have to dig it all back up.

Maybe someone here can inform me, howuch does the waste weigh? Would it be viable to launch it into space then send it on a course to the sun?

I don't think anyone wants to take the risk of having the launch vessel explode while still in the atmosphere.

Heh you know I didn't even consider that factor.

Move fast and break things! ...maybe not...

It's easier/less deltaV to send things out of the solar system than it is to hit the sun.

(Basically, to hit the sun, you have to scrub out all/most of the velocity from the Earth's orbit, or what you've done is put your waste in an orbit around the Sun that may intersect the Earth's at some point in the future)

It isn't sufficient to launch in the general direction of the sun, using the minimum energy required to escape earth's gravity?

No. For an entertaining explanation why, see https://www.youtube.com/watch?v=uNS6VKNXY6s

Obligatory xkcd: https://xkcd.com/1244/ (explanation and more details https://explainxkcd.com/1244/ )

The reason the Earth doesn't fall into the sun is that it's moving quickly enough that the centripetal force balances the Sun's gravity. If you escape the Earth's gravity well and give it a small push it would still have nearly as much orbital energy as the Earth and way more than Venus, which hadn't fallen into the sun either.

To slow down enough that you could fall into the sun you need to kill 30 km/s of velocity. To go fast enough to escape the solar system you only need about 15 km/s. And crashing into Jupiter is even cheaper than that.

Why not do an elliptical orbit that takes you close enough to the sun to burn up? That seems like less energy than dropping to zero no?

An elliptical orbit that gets close to the sun is nearly the same as an orbit that goes through the sun.

Besides, exposing radioactive materials to heat does not affect their radioactivity.

That's only true up to a point. I suspect that if you exposed just about anything to 100,000 kelvin it ceased to look like any kind of matter we know anything about.

> I suspect that if you exposed just about anything to 100,000 kelvin it ceased to look like any kind of matter we know anything about.

1e5 K? You're missing a couple orders of magnitude, there.

The hottest parts of the Sun's surface go up to 20 million Kelvin, and that doesn't "cease to look like any kind of matter we know anything about".

Yes, but there is SOME temperature at which heating things up does start to cause things to act weirdly. You know, like in a fusion reactor. That definitely changes the radioactivity of certain elements.

This experiment was performed thousands of times back in the 1950s and 1960s. A nuclear weapon's fireball is way hotter than 100,000K, and the exploding weapon contains lots of fissionable material and fission byproducts. The extreme temperatures don't destroy them, they just help spread it around.

Yup, you got me there. Speculating wildly ends poorly.

Close to the sun still takes more energy than leaving the solar system, similar to how it's just as hard to charge a capacitor to -9V as to 9V. And in what sense would it "burn up"?

Bring it up does not change the fact that there is now radioactive material on an orbit which still potential overlaps the earth. Out of the solar system is a much better solution.

On the other hand it's not like the Sun isn't spewing out way more radioactive material continuously than we're talking about adding here.

EDIT: To give some orders of magnitude, the back of the envelope tells me that the sun inflicts about 700 TBq of carbon-14 on us every year. For comparison, countries like the USSR and UK have dumped 85,000 TBq of radioactive waste into the ocean (and Fukushima added another 15,000). I don't know how to judge how much of the vaporized waste would end up back on Earth so it's quite possible I'm wrong in the above.

You'd still need an Earth-Sun transfer orbit, which is still a lot of deltaV.

http://i.imgur.com/SqdzxzF.png

Technically you could try some clever gravity assists with Jupiter to greatly reduce the ∆v requirements. But that's still a very expensive way of solving a non-problem. We know how to deal with nuclear waste. The problem is with people being scared out of proportion by it.

Amount of radioactive waste: A couple of tons every year per power plant is realistic.

Space dumping is a terrible idea. Expensive and risky.

Best storage solution so far found is what we've mostly been doing so far. Just having a sealed of area and store it for 20 or so years in a special low population and high security area that is protected from rain, frost, and temperature swings and have a good containment in case of container leaks. And then repackage in 20 years time for another 20 years. And so on. I.e. "actively managing" nuclear waste until the end of time.

Fun fact: The inner core of earth is not cooling mostly because of naturally occurring nuclear fission... so in a way our very own planet is full of radioactive waste already :)

My observation that tends to annoy people is to point out that the best place to store spent nuclear fuel is inside the original fuel rods. The best place to store those is next to the nuclear reactor. The objection seems to center around reprocessing. Course the longer you wait before reprocessing the less radio isotopes you have to worry about.

TERRIBLY hard to send anything to the sun. Stuff does not just "falls" there, you have to cancel the enormous translation speed that the Earth has.

Plus, putting the stuff on top of a highly energetic vehicle is not the safest thing we can do with it.

Here's one startup that is using a design that can convert spent fuel: http://www.transatomicpower.com/the-science/

Plenty of retiring Nuclear plants. Just do a conversion on the same real-estate and use the waste as fuel.

[EDIT] For a deep dive into Thorium, check out any one of the "Thorium Remix" vids: http://thoriumremix.com/2015/

Here's a list of other Gen IV reactor companies/projects (from Thorium Remix 2016):

Terrestrial Energy, Flibe Energy, Molten Energy, Transatomic, ThorCon Power, Copenhagen Atomics, Seaborg, Chinese Academy Of Sciences.

I uprooted unique_parrot2's comment, as it reflected my view about nuclear power, up until last year. Here is the documentary that changed my mind: http://pandoraspromise.com

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