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Hitachi Developing Reactor That Burns Nuclear Waste
Zothecula writes The problem with nuclear waste is that it needs to be stored for many thousands of years before it's safe, which is a tricky commitment for even the most stable civilization. To make this situation a bit more manageable, Hitachi, in partnership with MIT, the University of Michigan, and the University of California, Berkeley, is working on new reactor designs that use transuranic nuclear waste for fuel; leaving behind only short-lived radioactive elements.
Can we get more companies doing these please?
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Hitachi!
"as well as higher liklihood of meltdown,"
Nope.
Fukushima's error was that they didn't raise the sea wall like many recommendations had told them too.
They whole design is different, it's not really comparable.
The Kruger Dunning explains most post on
Will these new elements have significantly shorter half-lives? Will they themselves be able to function as fuel and could thus further be changed?
If both of these are true, even if they're still transuranics, then wouldn't it make sense to build a few of these reactors in geologically-stable areas?
We know the causes of the three biggest nuclear disasters, one being a maintenance task that went awry (TMI), one being an ill-considered test that led to meltdown (Chernobyl), and one being a natural disaster that caused the equipment maintaining the reactor to fail (Fukushima Dai-Ichi). We can probably avoid #2 and #3 based on good management techniques and proper site choice, and #1 is a matter of engineering/technical. If this would make it so that we don't have to attempt to tell two or three future civilizations how to avoid irradiating themselves then it might be worthwhile even if there are added volatility risks.
Do not look into laser with remaining eye.
Mmmmmm, no, you can definitely burn up transuranics and you pretty much HAVE to end up with less at the end of the day, but the question is whether or not you have LESS OF A PROBLEM at the end of the day because there are plenty of "short lived" radionuclides that you really would rather trade for some nice plutonium or americium. On top of that the entire structure, premesis, possibly nearby things, etc will become waste, and even low level waste is costly to deal with. This is the same sort of set of issues that have made it totally uneconomical to reprocess spent fuel. ANY handling is messy, dangerous, and produces a lot of expensive to dispose of waste.
"Malo periculosam, libertatem quam quietam servitutem." -- Jefferson
Don't LFTRs solve the same problem?
If you have a strong enough neutron flux then you can burn the waste (i.e irradiate it until it transmutes to something with a short-enough half-life). Unfortunately, only fast neutron reactors have neutron balance good enough to allow a significant fraction to be diverted for uses other than supporting the chain reaction.
Try here: new reactor design.
Politics; n. : A religion whereby man is god.
option A: moderate toxicity/radioactivity for (hundreds of) thousands of years
option B: EXTREME toxicity/radioactivity for decades
To me it seems a no brainer that option B makes infinitely more sense. The proliferation risks are honestly marginal, considering the alternatives. (increasing reliance on coal, or a never ending stockpile of option A. (So much of it in fact we're considering boring a hole in a goddamn mountain to stuff it into.)
The actors who'd be interesting in getting their hands on high level radioactive waste to cause mayhem would most likely be too inept to use it, and kill themselves in the process. The ones would be capable of putting it to use, probably have access to conventional weapons that would do more damage (consider a 'dirty' bomb vs a hijacked aircraft, or the type of bomb used in Oklahoma City.)
What is "neutron saturation transmutation"?
I'm also skeptical of their claims, as it appears to be a thermal-spectrum light water reactor and it's quite difficult to consume TRUs completely in the thermal spectrum, the neutron absorption cross sections are fairly large. Maybe they've got higher enrichment and so shitloads of excess reactivity, so they can afford to lose the neutrons, in which case I seriously hope they have a strong negative temp coefficient. Don't know, would be good to learn the details.
Not sure about the likelihood of meltdown being increased, though. I don't think the decay heat profile of MOX is significantly different from regular enriched Uranium fuel (decay heat melted Fukushima fuel, not fission heat).
By I much prefer inherently safe reactor designs.
Nuclear waste is only a problem if you have a massive misunderstand as to the scale of the waste. We're not talking about literal mountains of waste, we're talking about under 100,000 tons - for all of it from the USA since forever. You can do one big project and store all of it, nearly indefinitely. The story of Yucca Mountain is what happens when you have to involve people that want a project to fail instead of just getting the damn thing done.
X
Fukushima's error was that they didn't raise the sea wall like many recommendations had told them too. They whole design is different, it's not really comparable.
Not just the design but many other relevant circumstances too. I drove past San Onofre yesterday, currently inoperative. Noticed the really big hills immediately behind it. Putting backup generators and such on that higher ground might be useful too. I'm not 100% sure but I think backup generators were stored at the nearby US Marine Base, Camp Pendleton, and the Marines would helicopter them in if and when needed. If so on high ground, secured and mobile. Might be a better idea than more walls. Other coastal sites can probably take advantage of advantageous local conditions as well.
Will these new elements have significantly shorter half-lives?
In general the waste from a 4th gen reactor design is cited as being hazardous for a few hundred years. Something manageable, unlike the current situation where we are looking at tens of thousands of years.
Humm, let's see.
U-238 absorbs a neutron becoming Np-239 then decays to Pu-239
Pu-239 has only a 2/3 probability of fission upon neutron absorption
Water also has the tendency to absorb neutrons
It's no wonder that no TRU burning reactor has been proposed that uses water or helium for cooling, it's always sodium, lead or molten salt as coolant.
Also weird, is Hitachi already has a TRU burning design, the S-PRISM (GE/Hitachi project). Fast sodium reactors are actually known to be workable for that job.
> Fukushima's error was they didn't raise the sea wall
Also, the backup generators to operate pumps were in the basement that flooded. If the generators had been on the roof, it would have been fine.
I know hindsight is always easy, but it does seem like important stuff in a flood plain should be inspected and thought through once per year by smart people to find glaring problems like this.
>Nuclear waste is only a problem if you have a massive misunderstand as to the scale of the waste.
Incorrect, sir. Nuclear waste is only a problem if you have a massive misunderstanding as to the thing you apply the label of nuclear waste. For it is not nuclear waste, it's unspent nuclear fuel.
It would be foolish to build a massive pointless structure for nothing. Nobody's moving their nuclear "waste." It's not even waste to begin with. It's fuel.
Have you ever heard of a Molten Salt Reactor? The most famous one I know about is the LFTR proposed by Kirk Sorensen. These types of reactors also burn existing nuclear waste, but they do so at atmospheric pressure, and are inherently safe. See: http://www.investing.com/analysis/thorium:-an-alternative-source-of-energy-224358
We could build MSRs on site, so the fuel never has to be transported anywhere. Then we decommission the old dangerous water-based plants and run the safe waste-consuming molten salt reactors.
OCCUPY CARSON CITY presented this idea to the Nevada Committee on High-Level Radioactive Waste 7/2012. https://www.leg.state.nv.us/Interim/76th2011/Committee/StatCom/HLRW/Other/ResponsestotheSOR.pdf
This article confuses me because the Hitachi design is terrible. It uses pressurized water, which introduces all sorts of problems. The Molten Salt design is obviously better. I guess we'll just have to wait until 2020 to see how China does it.
but it does seem like important stuff in a flood plain
Fukushima wasn't in a flood plain.
should be inspected and thought through once per year by smart people to find glaring problems like this.
The problem wasn't glaring except in hindsight.
Clean power that can bridge capacity/fluctuation problems of solar and wind is just what we have been waiting for. I hope all the world governments tax rebate and finance the heck out of this to bring it to market in time to make an impact on worst effects of climate change.
...why didn't science just do this in the damn first place?!
It's never been cost effective. The same way safe coal mining and 100% safe fly ash disposal isn't cost effective. If you need to expend more energy to deal with the waste than you get out of it, it's not worth it.
....but what does the "short-lived radioactive elements" dissolve into? surely not *nothing*? ...how much can we strip away through processes before every part is used? ...how little matter do we need left over before we can eject it from the Earth's atmosphere into the Sun?
If we get it to the point that it's economical to launch in a rocket, then there's so little left that storage shouldn't be a big deal. And if it's safe enough to put on top of a rocket, then it doesn't need to be removed from our biosphere.
Most of the really radioactive waste is extremely dense. So it gets insanely expensive to get it out of earth gravity well. To make matters worse, we have no space launch systems that are reliable enough to use for this type of disposal. It's one thing to have a bunch of highly radioactive material sitting around in a shielded location. It's an entirely bigger problem to have a failed launch blasting toxic crap all over hundreds or thousands of square miles/kilometers.
It's also a waste of of non-renewable material with a high amount of potential energy that we may be able to do something with sometime in the future as our understanding of physics progresses.
Even ignoring the huge amount of energy required to launch something into space, our current launch vehicles are not the most environmentally friendly mode of transportation either.
Fukushima Daiichi's problems began forty years ago when they removed the natural 35 meter bluff that use to be there.
The plant is on a bluff which was originally 35 meters above sea level. During construction, however, TEPCO lowered the height of the bluff by 25 meters. One reason for lowering the bluff was to allow the base of the reactors to be constructed on solid bedrock in order to mitigate the threat posed by earthquakes. Another reason was the lowered height would keep the running costs of the seawater pumps low. TEPCO's analysis of the tsunami risk when planning the site's construction determined that the lower elevation was safe because the sea wall would provide adequate protection for the maximum tsunami assumed by the design basis. However, the lower site elevation did increase the vulnerability for a tsunami larger than anticipated in design.
Not considered in the above would be the simple yet modestly more costly possibility of obviating the need for a sea wall by preserving the bluff and setting the reactors back, using modestly sized canals to cycle the sea water to and fro. That, naturally, wasn't the cheapest conceivable option, so it didn't survive the bean counters. Instead, they removed 25 meters of foothill, a feature that was originally 2.5 times the height of the tsunami before they fucked it up. The whole `bedrock' smokescreen is easily dismissed for the lie that it is; they could have reached bedrock from a setback design with no more difficulty.
This was done for one reason; grading the beach provided cheaper access to the ultimate heat sink, sea water. Less construction cost, less pumping, less maintenance, etc. This isn't lost on the perpetrators either. They know they're at fault and they knew it at the time, whatever lies they tell today notwithstanding.
This isn't speculation, either. Fukushima Daini did not get submerged, did not melt down and did not contaminate the land and the sea. Why? Primarily because it was built at higher elevation, which is about the only significant difference between these sites.
TEPCO bean counters. End of story.
Maw! Fire up the karma burner!
Fukushima wasn't in a flood plain.
The area is periodically inundated by tsunamis. That would fit most definitions of a "flood". If Fukushima wasn't flooded, then neither was Noah, since that was salt water too.
The problem wasn't glaring except in hindsight.
Nonsense. Plenty of people thought it was a problem before it happened. The area is hit by a big tsunami about every 300 years. There are historical records of the last few, and geological sediment records of many more. The last one was 300 years ago. They were due.
The analyses collectively indicate that the two reactors appear to be able to achieve their design objectives: The RBWR-AC provides an equilibrium-cycle breeding ratio of slightly above 1.0, thus providing for a self-sustaining fuel cycle in which depleted uranium is used for the makeup fuel. The RBWR-TB2 is capable of unlimited continuous recycling of TRU while consuming on the order of 10% of the loaded TRU per recycle (after accounting for the newly generated TRU). Most results confirmed the values estimated by Hitachi. Some differences among the predicted reactivity coefficients need to be evaluated further.
This has the potential to be a game-changer if true, as we could simply use existing reactor designs such as the ABWR (of which there are several operating already) to both burn waste and breed fuel indefinitely from U238 feedstock.
It's Hitachi! Can't they just wave their Magic Wand and make the nuclear waste go away? Think of the buzz that would create!
I'm pretty sure the energy required to add a proton to the nucleus of a large atom is prohibitive.
I agree with your first statement, and I agree that Fukushima should have been prepared for that size of tsunami, but seriously.
The last one was 300 years ago. They were due.
THAT'S NOT HOW STORM FREQUENCY WORKS
He blatantly made a biblical reference to Noah
The story of Noah did not originate in the Bible. Both the Sumerian Epic of Gilgamesh and the Akkadian Atra-Hasis Epic included the story centuries earlier.
Hitachi means 'sunrise'. :)
Is that this is another solid fuel, boiling water reactor. Which means they have all this Rube-Goldberg-esque over-elaborate over-engineering to control the plant in a shutdown state. And if they miss even one little thing, boom. Steam explosion.
While burning up existing reactor wastes is a Good Thing, there are better, simpler, safer reactor designs for things like that.
Chas - The one, the only.
THANK GOD!!!
The area is periodically inundated by tsunamis.
That's not what "flood plain" means. A flood plain is an area frequently inundated by a river. Else everything under about 1000 meters is technically flood plain (from nearby several km asteroid impacts).
Nonsense. Plenty of people thought it was a problem before it happened. The area is hit by a big tsunami about every 300 years. There are historical records of the last few, and geological sediment records of many more. The last one was 300 years ago. They were due.
Plenty of people knew including the builders of the plant who had constructed seawalls capable of withstanding a tsunami about 5 meters shorter than the one that actually hit. What they didn't know until much more recently was that tsunami could be considerably higher than the original 1 in a century events. For example, the earliest work I've seen anyone cite was from 2001. The study by TEPCO (the operators of the Fukushima nuclear plant) reached a similar conclusion much more recently (I recall some point on or after 2008).
For some reason, there's a lot of people here who think that such knowledge can magically transform into a higher seawall overnight despite the participation of several slow bureaucracies in the decision making and construction process. They don't trust these bureaucracies to run nuclear reactors, but they expect them to act instantly on new information and spend gobs of money to address any threat, real or imagined.
These same people seem to forget that Fukushima was scheduled to start its decommissioning in 2013 as well (yes, the life of the plant was extended, but not at the time that the higher seawall would have been evaluated). Why slap up a higher seawall when the plant will stop operating in a few years? One needs a better argument than that a very infrequent earthquake could happen during that period of time.
It's mostly a United States problem that waste isn't reprocessed. This is now and has been done on an industrial scale in Europe and the U.K. for several decades. For some reason the United States, under the guise of non-proliferation, will not permit reprocessing of spent commercial nuclear reactor fuel.
The story in this article isn't news. Everyone knows how to reprocess spent fuel since before the 1960s. What would be actual "news" is the time at which the United States allows the well-proven, industrial-scale reprocessing to be applied to its own reactors.
Even Canada does it. The United States' nuclear energy policy is laughably stupid. It's a shame, really.
Kriston
I guess I should ask what you mean by "pretty sure". Adding to large atoms are a lot easier than small ones. It's been a long time since I've read about it, but it's called "proton induced fission". Admittedly, most of the reading when you Google it is a bit heavy. I do know that if you crack U238 with a proton that all 3 daughter isotopes have a half life of 35 days or less (one is like an hour and a half) and their daughter isotopes are all stable.
Anyway, if you Google "proton induced fission" and "nuclear waste" together you'll see there are already papers proposing the idea, such as this one:
http://www.npl.washington.edu/...
option A: moderate toxicity/radioactivity for (hundreds of) thousands of years
option B: EXTREME toxicity/radioactivity for decades
To the militarists option B is a Godsend
Whatever elements that make up the bulk in Option B are perfect for DIRTY BOMB
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What is "neutron saturation transmutation"?
Nuking it until it glows. First you separate your waste into constituent elements (their oxides, whatever) then you irradiate it with neutrons until most of the medium-level waste transmutes into something with a short enough half-life. You can optimize it a bit by playing with neutron energy to maximize the capture by most problematic isotopes. The size of neutron capture cross-section is not an issue, since you don't need those neutrons to support a chain reaction.
The concept is pretty old, but requires a shitload of neutrons (since you typically need to capture multiple neutrons to transmute a single waste atom). The only practical way to get that much is to use a fast neutron reactor. And even then it's marginal. In future, when we get fusion reactors, fusion neutrons could be used much more economically for that.
but it does seem like important stuff in a flood plain
Fukushima wasn't in a flood plain.
Yes it is. Take a look at this US Army topo map (the latitude is (37.427 degrees, its on the coast). It is on an extended flood plain stretching along the coast, created by several rivers (Takase, Maeda, Kuma. Tomioka, etc.) . The whole area is a sea-level marsh consisting of soil deposited by these rivers at flood.
The problem wasn't glaring except in hindsight.
Because, you know, no one had ever seen a tsunami in Japan before. Oh wait, tsunami is a Japanese word. That doesn't seem quite right, does it?
Japan had fifteen of them since 1900, before Tohoku (the slightly dated linked list misses the 2007 Niigata tsunami).
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
The area is periodically inundated by tsunamis.
That's not what "flood plain" means. A flood plain is an area frequently inundated by a river. Else everything under about 1000 meters is technically flood plain (from nearby several km asteroid impacts).
Fukushima Daiichi is actually on a flood plain though. It is on an extended coastal sea-level estuarial marsh plain deposited by a series of rivers coming down from the mountains. BTW - there is no "frequent" required. Flood plain maps mark 100 year and 1000 year flood boundaries, something on the 1000 year boundary is still on the flood plain, even though that part floods rarely.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
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Depending on radiation exposure, you might be good for 5-7 days....
It wasn't even the seawall height that was the real problem, since any seawall could eventually enounter a larger tsunami than it was designed for. Even the old reactor design used there is very forgiving in the sense that if the plant totally loses power after being scrammed and the backup diesel pumps don't work, you have plenty of time to connect an external coolant water source to the reactor and pump water through it for a few weeks to pull away heat of decay.
But at Fukushima the disaster was so large in scale that all the modern-day infrastructure surrounding the plant was washed away. A fire company eventually got through, but didn't have the right connector to join its pumper hose to the reactor. This is the kind of idiot basic stuff that makes acts of nature so much worse.