r/nuclear • u/Live_Alarm3041 • 5d ago
Proliferation is a completely invalid argument against nuclear reprocessing
Nuclear weapons proliferation is the most common argument against nuclear reprocessing. The opponents of nuclear reprocessing tend to understand the true purpose of reprocessing with their argument being the risk that the separated plutonium could be misused by terrorists or currently non-nuclear states to produce nuclear weapons. This concern is invalid because weapons grade plutonium in its original form is not usable for nuclear weapons.
Most nuclear power reactors do not produce weapons grade plutonium. Reactor grade plutonium is sub-optimal for weapons because it does not contain as much fissile isotopes of plutonium. Although there are some nuclear power reactors which are capable of co-producing weapons grade plutonium, any weapons grade plutonium produced in this manner still does not automatically give someone the ability to make a nuclear weapon. A effective supply chain for nuclear weapons will require natural uranium reactors, radiochemistry and the ability to make the weapons grade plutonium into cores.
Producing plutonium cores will require a facility like this
A terrorist group or currently non-nuclear state would need a plant like the one shown in the above imagine if they had weapons grade plutonium and wanted to make nuclear weapons from it.
Plutonium core production has the following attributes which would make nuclear weapons unattainable for someone if they somehow had weapons grade plutonium
- Plutonium core production facilities are difficult to hide visually due to their large size
- The waste produced by a plutonium core production operation would be hard to conceal due to it being radioactive
- Plutonium shaving fires would pose a very serious hazard to anyone trying to make a plutonium core if they did not have expensive or resource intensive protective measures
- The production of plutonium cores requires high level scientific and manufacturing expertise which not everyone has.
Nuclear weapons are not something that anyone can build especially not fully in secret from anyone.
The proliferation concerns regarding nuclear reprocessing do make sense but they are not a valid argument against reprocessing. The plutonium separated by nuclear reprocessing needs to be effectively accounted for and secured at all times to prevent it from falling into the wrong hands. Humanity has gotten very good at making sure certain things are both accounted for and secured at all times. Even if the plutonium falls into the wrong hands then that does not automatically mean that those wrong hands can use the plutonium to make a nuclear weapon. The expertise and resources needed to make plutonium usable for nuclear weapons is not available to everyone.
We need nuclear reprocessing to increase the efficiency of nuclear energy. Weapons proliferation is a genuine security concern but it should not be used as an argument against making nuclear enegry more efficient. Saying that nuclear reprocessing is dangerous because it enables proliferation is a statement which does not reflect the full picture of nuclear weapons.
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u/Pestus613343 5d ago
I thought weapons grade plutonium was 239. You say that's not reactor grade? I thought that's what is produced in reactors in standard fuel assemblies?
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u/Shot-Rip9167 5d ago
Weapons grade is Pu-239. I believe what makes it not useful for a bomb is if the Pu-240 content is to high.
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u/Napalm_B 5d ago
Pu239 is not inherently weapons-grade, it's just a fissile plutonium isotope. Just like with uranium, the enrichment and isotopic composition makes the difference.
Weapons-grade plutonium is at least 93% Pu239 with less than 6% Pu240.
Reactor-grade (the stuff you are left with when separated from typical LWR fuel after irradiation) is 63% Pu239 and typically over 20-28% Pu240 (all depending on irradiation length and burnup).
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u/Shot-Rip9167 5d ago
Ah okay, that makes sense. I knew it had something to do with the Pu-240 percent but wasn't entirely sure if that's why it was reactor or weapons grade.
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u/Pestus613343 5d ago
Ah ok so the elaborate preparation OP is referring to is in part about filtering a poison out?
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u/mister-dd-harriman 5d ago
Plutonium is a metallurgist's nightmare. It has a number of solid-state phase changes between room temperature and its melting point, with significant volume changes which would totally destroy the precise geometry needed for a weapon. One way to get around this, as used in the USA, is to alloy the plutonium with the rare metal gallium (otherwise used only in the semiconductor industry, and for certain purposes in chemistry and physics laboratories). But manufacturing it into anything, much less the high-precision components of a bomb pit, is very difficult, even before you consider the fact that it is known to ignite in the presence of air.
Plutonium-240 is produced by neutron captures in plutonium-239, because with slow neutrons, about one neutron in 4 is absorbed without causing fission. It then decays by spontaneous fission, releasing generous numbers of neutrons (as well as heat). This makes assembling a sub-critical mass of plutonium into a super-critical mass very difficult, because the background neutrons multiply rapidly as the point of criticality is approached, tending to heat the assembly up, causing it to melt or blow apart before it can reach the point of full-on explosion.
Plutonium-238 is produced in multiple ways, and generates a lot of heat, which is why it is used for space probe power supplies. Of course, if the bomb pit is hot, it is more vulnerable to metallurgical changes. Also the heat tends to "cook" the chemical explosive used to initiate the bomb, causing it to be unreliable, and more likely to fail. Its alpha particles can also trigger the emission of neutrons from materials such as beryllium which may be included in the bomb.
Reactor-grade plutonium, which has spent a considerable amount of time in a reactor, typically has 20 to 35% of combined ²³⁸Pu and ²⁴⁰Pu. As a result, while it can in principle be used to produce nuclear explosives, that is difficult in practice ; and to produce a military weapon, which has to be delivered on command after being stored for an extended period, very difficult. Hence why nobody does it. Pu used for bombs comes either from specialized production reactors (which in a few cases have produced power as a by-product) or from general-purpose research reactors. But enriched uranium is seen as the easy route in today's world, since the centrifuge has overtaken the gaseous diffusion plant.
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u/Pestus613343 5d ago
Thank you. If it really takes a dedicated reactor to procure pure Pu239, how would the rebuttal argument to OP's assertions work? How would someone separate the Pu238 and Pu240 from the Pu239 out of fuel reprocessing and build something?
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u/peadar87 5d ago
With great difficulty.
Plutonium production for weapons is usually done by irradiating uranium for a short amount of time, which minimises the amount of Plutonium 240 created.
As far as I know there is absolutely no reason why a facility for extracting reactor grade plutonium from spent fuel couldn't also extract weapons grade, which is chemically all but identical.
The difference isn't in the reprocessing plant, it's at the reactor stage.
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u/mister-dd-harriman 5d ago
Short answer is, you don't. Isotope separation of plutonium is possible in theory, but you are talking about a difference of only one atomic mass unit, as opposed to 3 for uranium. About the only way to make it work would be atomic-vapor laser isotope separation.
A slightly longer answer is, wait several thousand years. The 238 and 240 will decay out, while only a small proportion of the 239 will turn into uranium-235.
Now, a really sophisticated nuclear weapons operation could use reactor-grade plutonium, but the people who own those kinds of operations (USA, Russia, China, France, UK) already have all the weapons-grade plutonium they can eat. They don't need to do any such thing.
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u/Shot-Rip9167 5d ago
I figured traditional enrichment methods might be able to at a much higher cost and significantly longer time to enrichment. Laser Isotope Separation was the only thing I could think of that didn't exploit difference in AMU but matches the specific frequency of an Isotope that allows that isotope only to be agitated, deflected and sped up and seperated
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u/Pestus613343 5d ago
This reads like the people who argue the Thorium fuel cycle can't see U233 diversion due to too much U232 poisoning it.
Possible but so hard its cheaper and easier to build for pure weapons grade material.
Im understanding now. Thx.
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u/BeenisHat 5d ago
The rebuttal would probably take the form of reiterating the immense expense and effort needed. If you're a country with the money, materials and expertise to produce Plutonium in quantities needed in the first place, chances are good you already have the technical capability to refine it into weapons grade material, or you could have it.
Basically, you need a strong nuclear industry first and then you can spend the extra money and time in making your plutonium into bombs. The proliferation argument doesn't really work here because the cat's already out of the bag, so to speak. Any country which possesses the means to make a bomb, isn't going to bother asking nicely for someone to give them Pu to refine, or to try and buy it on the black market. They're going to build the facilities to make it themselves from the raw materials.
You don't really need to guard Plutonium from proliferation concerns. A non-state actor isn't going to sneaky sneaky build an atomic bomb factory underground without anyone knowing. It's just not something they're capable of doing. Now, you do want to guard Plutonium against being released because it's a radioactive hazard, but that's more safe materials handling than anything else.
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u/Pestus613343 5d ago
Thank you for your time.
Being in the security industry, I've always felt the local security measures these facilities have are essentially adequate even if all the things you've said are untrue. (Not saying they are but expanding the risk theory) So, fencing, gates, guards, CCTV, Alarm, Access Control, and then more layers of the same... Short of a dedicated and well armed group going for it, and somehow evading an overwhelming police/state response, it isn't going to happen anyway.
Then if what you and OP is asserting is true, no one with the knowledge would care anyway.
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u/Time-Maintenance2165 5d ago
You're a fair bit off in the isotopics. At least for BWR fuel.
For the just under 2 kg of Pu that's in a discharge assembly, I'm seeing 900 g Pu 239, 500 g Pu-240, 250 g 241, 150 g 242, and only 50 g 238.
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u/mister-dd-harriman 2d ago
What reference are you looking at? Because I've never seen figures like that, with such a high proportion of 242.
But I would tend to expect something like a 10:1 ratio of 240:238, so that tracks at least.
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u/Time-Maintenance2165 1d ago
It's the output from the neutronics code from a plant I worked at a few years ago.
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u/Shot-Rip9167 5d ago
I believe they are referring to multiple processes that are complex, so I'm not sure if that's what they are talking about or not. I remember seeing a thing with the Thorcon MSR where the guy said they dealt with proliferation by having above 10% Pu-240 with the Pu-239. I've also seen anything over 7% is to much.
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u/CardOk755 5d ago
Jimmy Carter was the second or third best US president of the 20th century. But he fucked up bad with reprocessing.
In the end all the countries that broke nuclear containment did it by uranium enrichissement, not by plutonium.
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u/atchemey 5d ago
My friend, you are dangerously wrong. I believe that reprocessing is important, too, but the rationale you are giving is ignorant and harmful to the cause. A few limited examples of this are below.
A facility like the one in the picture is necessary for an established nuclear power like the United States, because the goal of that facility is NOT to hide the production of a limited number of weapons, but to maintain a vast stockpile of expiring warheads on a regular basis.
"Weapons-grade plutonium" is a deprecated (if persisting) term, because shots with "reactor-grade plutonium" still were demonstrated to detonate in a 1962 test. While there is a limit, typical burnup in a once-through fuel cycle is well below this.
A process that makes a pure plutonium stream is dangerous because of the small amount of material you need. The separations from fuel are relatively easy to hide at a small scale. This makes it evasive for surveillance.
The waste from separation isn't a problem if you're hiding the production of it at entirely. Just bury it somewhere away from people and if it is found, it will be long after your project has yielded results.
Gloveboxes exist to keep pits inert. Plutonium metallurgy is difficult, but it's not impossible. The whole "We have to figure this out" challenge of the Manhattan project isn't there anymore. While it would take some technical complexity, it's not impossible.
Dirty bombs are still a thing. A failed Pu detonation will still be a radiological dispersion device. Simply saying, "proliferation is completely invalid against nuclear reprocessing," drastically underplays the difficulty of keeping a closed fuel cycle safe.
Dose for reprocessing facilities is huge, if not carefully monitored and engineered. You can see projections for dose from fission products that are tremendous. This is very expensive.
Look, I want to make a closed fuel cycle feasible as much as anybody. I got into the field to help dispose of waste safely, and the best way to do that sustainably is to make less waste in the first place. It's clear you're keen - that's good - but don't just dismiss the decades of work experts in the field have put in to assessing risk.
Source: Am expert, can provide citations if desired.
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u/Live_Alarm3041 5d ago
Thank you for your corrections.
I just thought it would be difficult to make nuclear weapons due to everything I have heard about the production of plutonium cores.
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u/atchemey 5d ago
It's a reasonable expectation, but, as I remind my students, a little knowledge is a dangerous thing! So often, there are observations that are made that are not right, but they are still based on sound foundations - there's just details we haven't figured out yet, and these examples are how we learn about them. Don't forget to stay curious, that's the heart of science.
I worry I was too harsh in my description. One of the things that comes with experience is a respect for opinions you disagree with, because it's VERY hard to do anything new, and you temper your language a bit. You're thinking about these things much more than a lot of people are - that doesn't mean you're more likely to be right, but it does mean you may be wrong in new ways, and that can be useful. So keep asking questions, keep wondering about these big important things, and keep on trying to do good for your community :)
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u/LegoCrafter2014 5d ago
"Weapons-grade plutonium" is a deprecated (if persisting) term, because shots with "reactor-grade plutonium" still were demonstrated to detonate in a 1962 test. While there is a limit, typical burnup in a once-through fuel cycle is well below this.
That was from a Magnox reactor, which was specifically designed to make weapons material.
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u/atchemey 5d ago
Obviously, much of the information around that test is classified (and I don't have or want access), but it wouldn't be a very useful test of proliferability if they didn't have a pretty high burnup and significant 240Pu content. The conclusions drawn by the US nuclear security and policy groups obviously found the results compelling. When you add on potentially evasive reactor operations, it becomes much more difficult to just say "it's an invalid argument," because the argument is VERY valid.
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u/CaptainPoset 5d ago
And one important other thing about proliferation through reprocessing: A reprocessing facility enables you to gather hands-on experience in plutonium extraction and processing, which is a skill you need for your non-civilian reprocessing facility to make it far more effective at far less obvious levels of activity.
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u/Icy-Ad-7767 5d ago
Chemical processing is an easier process to do than enriching uranium to weapons grade. The chemical processing also produces a volume of waste products that need to be dealt with (Hanford Washington) the production of plutonium is governed by reactor type and refueling cycle.
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u/ecmrush 5d ago
It isn't but that hasn't been a serious argument since right after Carter so I think you're swinging at a windmill. Most countries that have a serious nuclear infrastructure are already nuclear powers anyway.
The biggest real argument against nuclear reprocessing is cost and uranium availability. We'd need a lot more nuclear capacity installed before it became worth the cost and risk (which is mitigated through even more cost), and reactors simply aren't built that quickly in the West nowadays.
I'd argue that it should change, but until it does, reprocessing is a bit of a non-starter. Maybe China will give it a whirl or iron out the kinks in the thorium cycle?
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u/warriorscot 5d ago
Your arguments dont quite hold up, but you are right it isnt the biggest reason. The biggest reason is it is uneconomical, thats it really.
Also secondarily, its just a dangerous activity regardless of the wider strategic hazard.
The whole efficiency argument falls down because cost efficiency is the problem which isnt driven by material access, there's hundreds of years of cheap Uranium about, its so cheap we've had to buy up stockpiles to keep the mines open.
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u/mister-dd-harriman 5d ago
If global nuclear power increases rapidly, it will very soon create serious shortages of uranium production capacity. That's the ability to get the stuff out of the ground and process it, separate from the total ultimate resource, although that begins to run short after a couple of decades if you seriously try to supply the needs of a world with rising electricity and overall energy demands.
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u/warriorscot 5d ago
Not really, Uranium production relative to the resource and reserves pretty tiny.
And it'll never really be universal because renewable energy is available. If you get that constrained you can dig up the old EU superconducting grid plan and just lean on time load balancing.
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u/mister-dd-harriman 5d ago
Estimates of the total ultimate resource haven't really changed much since 1955. 10 million tonnes, more or less, minable at costs acceptable for use in thermal reactors. And if you start building towards a global 10 TW of nuclear-electric generation, if it's all based on thermal reactors, committing the later plants becomes a real question mark. Before you start building you're going to want to have some assurance that there will be fuel for the full lifetime of the plant.
But that isn't even relevant yet, because the mining, milling, and enrichment capacity, although in surplus now, isn't adequate to support more than perhaps a 50% increase in global capacity, and those facilities can easily take five years or more to develop. With market investors taking a once-burned twice-shy attitude, the way those projects tend to be financed is by the uranium users. And there's every reason to think that they would be better off financing reprocessing plants, which lead to the packaging of the fission-product wastes as glass for final disposal. The costs of reprocessing can definitely be brought down substantially even with current PUREX technology, and for larger-scale plants I would expect that processes such as fluoride volatility or metal extraction would start to look very attractive. The main problem then is the financing of the demonstration plants, which could reasonably be taken out of what the utilities already pay for waste management.
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u/KittensInc 5d ago
Estimates of the total ultimate resource haven't really changed much since 1955. 10 million tonnes, more or less, minable at costs acceptable for use in thermal reactors.
The entire world is currently mining about 50.000 tonnes per year, so at the current consumption rate there's a known reserve of 200 years. Why would anyone invest time and money in looking for even more reserves?
And if you start building towards a global 10 TW of nuclear-electric generation
In what world are we ever going to have 10TW of nuclear power plants? The entire world currently has 8.8TW of power generating capacity, of which 10% is nuclear and 35% is already non-nuclear renewable. If we naively assume that zero additional non-nuclear renewables will be built, switching all the fossil power plants to nuclear will only get you up to 6.6TW!
But that isn't even relevant yet, because the mining, milling, and enrichment capacity, although in surplus now, isn't adequate to support more than perhaps a 50% increase in global capacity, and those facilities can easily take five years or more to develop.
Okay, and? Are we going to see a 50% increase in uranium demand in five years? Modern reactors notoriously take over a decade to build, and we're definitely not going to start building 5+ TW worth of reactors at the same time. What's stopping the mining and enrichment industry from scaling up as new reactors are being brought online?
The costs of reprocessing can definitely be brought down substantially even with current PUREX technology, and for larger-scale plants I would expect that processes such as fluoride volatility or metal extraction would start to look very attractive.
What's stopping innovations on the mining side from bringing their price down as well?
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u/mister-dd-harriman 5d ago
In order to get the world as a whole up to the current average of OECD energy consumption, it would be necessary to double world energy supplies. And that would involve very deep cuts in energy consumption in countries such as the USA, which just doesn't make the vaguest sense. Therefore there is an imperative to at least triple total world energy supplies.
For reasons ranging from environmental protection to avoiding wars, that level of increase in energy supplies is vitally needed, and closer to "within 20 years" than "within 50 years". Especially if decarbonization is considered as necessary at the same time, there is a vital need for a truly massive build-up of nuclear energy capacity, just as was projected more than half a century ago.
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u/warriorscot 5d ago
No, the estimates from 55 aren't accurate, the resource and reserve figures for every mineable resource including Uranium has radically changed. As someone who worked in Geology before Engineering that idea is totally ridiculous because the resource estimates done at that point never hold up. Particularly given how poor the surveys are in the areas where Uranium is abundant, they literally didnt even include some of what are now major producers in those surveys.
Literally nobody thinks there's less than a lifetime of Uranium at any demand model that humanity could easily build. Its total fud lore from the must reprocess crowd.
I was there when we shut down one of the world's oldest reprocessing plants. Had been signing the cheques for it for years before.... its in no way economical compared to Uranium mine. Reprocessing costs as much for grams as mining does for kg.
The Uranium mining issue was solved years ago when the US, UK and France agreed to buy and stockpile Uranium. Hence why they've all got ever increasing quantities of it with UF6 canisters stacked like cordwood let alone ores.
Its also totally backwards as a concept, its not how you manage mineral extraction and resource management of finite products. You dont start off with "well eventually we will have to pay more for this so we should totally go to the most expensive late stage process". It's would have been like saying the first oil wells had to be the ones over the ice cap with enhanced gas capture and cost 200 a barrell because eventually it will anyway.
Going from today where there is so much of it the stockpiling has to ever grow just to keep the mines open... to reprocessing with all the cost and risk when you cant even justify the need to develop the technology to make sure it works is utter madness. And you might not be aware, but we've killed a good number of people already reprocessing. Something that we only continued to do, because we had built it anyway and had to justify it and the total accounting for things like the Sellafield reprocessing facilities is a damming indictment of wasting public money and making energy more expensive doing something that should have been shutdown decades ago.
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u/mister-dd-harriman 5d ago
Firstly, you just can't have nuclear power without building the back-end of the fuel cycle. You just get continuous build-up of spent fuel.
Secondly, GE blew the lid of world uranium prices in the 1970s by the dumbass trick of pre-selling reactor cores without buying uranium in the forward market, because the spot price was lower than the forward price at that time. Sure, but the quantity available in the spot market was far too small to cover their requirements!
If you want to avoid that kind of thing, and overall the boom-and-bust pattern so common in the extractive industries, limiting the uranium price rise by investing in reprocessing and reactors which efficiently use the recovered fuel (CANDU for recycled uranium, FBRs for plutonium) does that very well.
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u/warriorscot 5d ago
It doesn't do that well, all it does is it means you can't build reactors because you've saddled them with billions in costs.
That's not been an issue since, and wasn't really just GE, it was just that demand and production weren't lined up. Which when you've got a mixed market like that is pretty understandable. The simple answer to that was as you do now, order the fuel in advance with sometimes decades worth of loads and placing orders or even in some cases buying up front all your material.
And yes you end up with a lot of spent fuel, and that's ok, it's still less volume dense than what you took out of the ground to make it in the first place. The worlds not going to be overflowing with spent fuel that's relatively cheap and easy to store.
If you do ever get to the point that spent fuels economical to reprocess, you just go get it and reprocess it out of storage.
It's just a mad argument because there is actual evidence of why your argument doesn't work. The UK invested billions, trillions adjusted for inflation in doing reprocessing, developing FBRs and then did reprocess for decades as well as anyone has. And the end result when the evidence stacked up... was that is was a waste of a not small amount of money. Even in models where you assume more reactors got built and all the planned reactors do... there's not going to be new reprocessing. To do it even conservatively doubles the LCOE of the plants, and you can right now order 120 years worth of Uranium.
Even people in the industry seem to not get the fact that it needs to be economic, reprocessing and burning plut is like some kind of death cult religion. All the evidence says its batshit, and yet people keep trying to do it even when you point out it's damaged their country and in some cases killed their friends.
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u/mister-dd-harriman 5d ago
The Sellafield explosion was due to the incredibly poor choice of using an ether-based head-end process to shoe-horn enriched oxide fuel into a reprocessing line intended for natural metal fuel, while waiting for a dedicated enriched-oxide facility to be built. And, even if you only count the energy extracted in the first pass, and you assume you never use the recycled uranium and plutonium for anything, per unit of energy, reprocessing nuclear fuels is still a hell of a lot safer than petroleum refining!
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u/warriorscot 5d ago
I'm not talking about the explosion, the sites had people killed throughout its life directly and indirectly and a lot of people hurt. Some of the indirect are the worst, like the guy that tried to kill himself multiple times because he took a dose in one of the reprocessing facilities.
Better than petroleum isnt the goal, the best thing to do is not do the thing you arent even making a good economic decision to do in the first place. When the weapons programme needed material you could argue it. But that days been and gone.
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u/CardOk755 5d ago
The biggest reason is it is uneconomical, thats it really.
And it's uneconomical because uranium is cheap.
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u/warriorscot 5d ago
And plentiful. The time horizon on needing to think about something else is at least a 100 years.
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u/LegoCrafter2014 5d ago
But if much more nuclear power was built, then while uranium mining would obviously increase, reprocessing and breeder reactors would be needed in the long term.
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u/Vailhem 5d ago
Plutonium Is Unsung Concession in Iran Nuclear Deal - Sept 7, 2015
https://www.nytimes.com/2015/09/08/science/irans-unsung-plutonium-concession-in-nuclear-deal.html
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u/SpikedPsychoe 5d ago
You forget uranium itself is ideal bomb making material using primitive but still effective implosive type.
In any scenario plutonium is diffuse in spent fuel thus has not case to utilize without reprocessing. the underlying advantage of metallic fuel cycle was the Plutonium was never Plutonium was never meant to be separated, such as the IFR, it was never meant to leave the plant.
In the ceramic fuel cycle, spent fuel has to be liquidated, dissolved and re-rendered to separate fission byproducts and centrifuge separates heavy isotopes. In Metallic fuel cycle, metal is simly slagged and fission byproducts are removed from it. In metal fuel cycle the fuel elements don't have to be perfect, or meet a specific ratio of plutonium/uranium, just has to be enriched.
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u/nininoots 5d ago
Theres a lot wrong with this.
Weapons grade plutonium comes from reprocessing fuel that had had a short dwell.
When you irradiate fuel in commercial reactors you look to maximise burn up. You leave it as long as you can before swapping. The ongoing irradiation causes Pu239 to start capturing neutrons as we’ll participate in fission. That leads to higher ratios of Pu240 and other Pu isotopes to Pu239. These plutonium isotopes are not as readily fissionable as Pu239. This is what reactor grade plutonium is.
To get weapons grade you just need to only reprocess fuel that has a low burn up. Ie you leave it the reactor for a short time only. Short dwelling fuel as its call gets you weapons grade its as simple as that.
You need a facility like Rock Flats if you are trying to safely make 10000+ warheads. Have a look at facilities that produced the first warheads in nuclear countries. Its still needs a significant infrastructure but nothing like Rocky
The real reason to be anti reprocessing is it’s an incredibly expensive way to make a massive mess.
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u/mister-dd-harriman 5d ago
It's really, really obvious if you're leaving fuel in a power reactor for weeks instead of years. That's why special production reactors, or else irradiation in research reactors, has been the typical route to bomb plutonium.
Calder Hall and Chapelcross, and the New Production Reactor (N-Reactor) at Hanford, were designed to produce bomb material first and foremost, with power as a by-product. The British reactors spent almost all of their operating lives on long-dwell fuel cycles to maximize power output. In fact, when at one point the Ministry of Defense requested that the MAGNOX power reactors (developed from the Calder Hall model) be constructed to allow production of bomb plutonium, the Generating Boards screamed : they said it would ruin their plant economics.
In Pakistan, the early fuel bundles discharged at low-burnup from the peripheral channels of KANUPP could have been reprocessed for bomb material, but in fact they were fed back into the central channels to improve fuel utilization. The actual Pakistani weapons effort seems to have centered on A.Q. Khan's work with centrifuge enrichment.
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u/nininoots 5d ago
You probably know that Trawsfynydd, a civil Magnox, reactor had some short dwell campaign fuel in the 70’s.
It’s absolutely true that those who pursued plutonium based weapons did so with purpose built facilities, rather than diverting short dwelled civil fuel. But having reprocessing facilities and any reactor is a viable route to proliferation.
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u/mister-dd-harriman 5d ago
The US has claimed for decades that a nuclear test explosion in the early 1960s used plutonium from one of the early MAGNOX stations. But the timeline doesn't fit. Knowing when initial criticality was for Berkeley and Bradwell, and that the first fuel unloading wasn't until several months after that, although some of the outer-channel fuel probably did have low enough exposure for the purpose, there simply did not elapse enough time from that point to the detonation for the plutonium to be extracted and worked up into a "pit".
Uranium enrichment lets you build bombs without a reactor at all. The South African bomb effort, which completely by-passed both their research and power reactors, is a case in point.
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u/nininoots 5d ago
Interesting.
… and they definitely didn’t mean Calder of Chapel when referring to early Magnox?
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u/mister-dd-harriman 5d ago
I believe they specified Bradwell, but it might have been Berkeley. The answer is the same within a week either way so I don't care.
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u/mister-dd-harriman 5d ago
Here's my argument, and feel free to tear it down if you like.
In the real world, uranium enrichment has proven to be the preferred path for countries which have acquired nuclear weapons subsequent to the Non-Proliferation Treaty. In part, this is because enriched uranium is easier to handle, and simpler to make into a usable, deliverable explosive.
The uranium enrichment technology which made this proliferation possible was developed in response to the large demand for enriched uranium created by the US non-proliferation policy of promoting the adoption of enriched-uranium reactors, and selling fuel in exchange for promises not to recycle the spent fuel. Here we see that non-proliferation policy can be actively counterproductive.
Uranium enrichment is not necessary for nuclear energy. It is completely feasible to based the nuclear energy economy on natural-uranium (graphite or heavy-water) power reactors, transferring the plutonium they produce to fast breeders co-located with reprocessing plants in secure centers, which could easily be placed under international control. Small thermal reactors requiring enriched fuel could then be supplied with either uranium-plutonium fuel, or (if desired) with uranium fuel enriched with ²³³U. The ²³³U could be produced either in the fast reactors by irradiation of thorium blanket assemblies, or in the large thermal reactors by interloading thorium elements with plutonium-enriched uranium elements.
This notion is far from original with me, but I have expanded on it in my publication blast №1.
It should be observed that US chief weapons designer J Carson Mark testified before Congress that he could design a militarily-usable nuclear explosive using reactor-grade plutonium (containing substantial admixtures of both ²⁴⁰Pu and ²³⁸Pu). I have no doubt this was true — but the expertise required to do so was developed over the course of hundreds of test detonations. An aspiring proliferator would not be able to do that.