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ORNL Restores US Capability To Produce Plutonium-238 (ornl.gov)
hypnosec writes: Oak Ridge National Laboratory has successfully produced 50 grams of plutonium-238, an isotope that produces heat without a lot of other, problematic radiation. This makes it suitable for use in radioisotope thermoelectric generators, which can power space probes. The new sample effectively revives the U.S.'s end-to-end plutonium-238 production capabilities, which have been dormant for around 30 years since work was stopped at the Savannah River Plant in South Carolina. The ORNL is optimistic this important milestone will pave the way for regular production of the material, ensuring constant supply for NASA's future missions.
... until your rover detonates. :P
Anons need not reply. Questions end with a question mark.
Cassini.
WE don't want some random Libyan terrorist stealing it and recruiting a local mad scientist to make nuclear bomb. But if the scientist steals the Plutonium to make a time machine...
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Cubs Win!
Look at the big stick. LOOK AT IT.
Yes, it is radioactive, and yes, it is a very nasty heavy metal... but there are still pacemakers ticking away with this stuff as the "battery" 25+ years later.
I wonder if Pu-238 might have some use in areas where batteries are needed and extremely hard to replace other than space projects. Definitely not for a battery for a smartphone, because we don't want Youtubers like TechRax to get radiation poisoning, but airline flight data recorders come to mind.
The world is quaking in its collective b00ts! I just snorted 50g dude and look it me!
The ornl thing was fucking hilarious
Why would the US build a plutonium bomb when it has something like 4000 uranium bombs? That would be a step backward. For what purpose?
* GayWAD is neither affiliated with nor endorsed by DICE or DHI.
So that means that GayWAD is affiliated with SlashdotMedia?
Yeah, because simply pulling out of the New START treaty and stopping the progressive dismantling of our massive nuclear arsenal would be way too easy... *rolls eyes*
When will he be back?
Who gives a shit what foreigners think about the US. It's of no consequence. And reviving the nuclear cycle needed to produce plutonium is no big deal. The US already has a few thousand nuclear missiles positioned all around the world. Creating plutonium to use as a fuel source for space vehicles is a valid justification for producing the plutonium. However, the morons around the world, as usual, are free to make up and publish anything they want with their reality distortion field turned on.
All plutonium isotopes are not made equal.
Pu-238 = great source of heat, not a great source of boom.
Pu-239 = great source of boom, not a great source of heat.
Pu-240, Pu-241 = not a great source of boom or heat.
Pu-238 is not used in weapons specifically because it fissions too fast spontaneously. That's why it makes so much heat. And, because of this, your weapon would have a significant portion of it reduced to not-plutonum and neutron poisons by the time you want to use it.
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You do know that the vast majority of the US nuclear stockpile is Plutonium-based weapons, right?
Plutonium takes far less material to create a critical mass, which makes for a lighter weapon. A lighter weapon means you don't need a big-dick huge fucking rocket to put the thing where you want it to be, and instead can use smaller rockets and missiles for deployment. And, if you aren't under the microscope, making Plutonium is easier than separating an ass ton of U235 from an even bigger shit ton of U238 through gaseous diffusion in a centrifuge cascade.
Slashdot still doesnâ(TM)t support Unicode after it was added to the HTML standard in 1997.
If Iran or NK did this, the US would be threatening war.
Hypocritical, asshole Americans. Go to hell.
I was hoping NASA would develop on Americium-241 power supply instead. Yes, it is heavier, but Americium-241 is in nuclear waste, and merely has to be separated out. America might be able to buy it from France at a low price. Is this reactor going to cost over $10 million a year to operate, and produce 1.5 kg/year?
Ugg... Peltiers are about 10% efficient, meaning you'll need to dump 90% of the heat coming out of the PU-238...
Stupid 4+ minute wait.
Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
Who gives a shit what foreigners think about the US. It's of no consequence.
Wrong. The U.S. does more than 4 TRILLION dollars a year of business with the rest of the world. Its scientists and schools collaborate with institutions around the world to advance the sum total of human knowledge, and its schools educate and shape the views of many members of the educated and ruling classes in countries around the world. It also has foreign policy interests that range from offering humanitarian relief after natural disasters and combating human trafficking to building coalitions against terrorist regimes that target it.
Just because it's of no immediate concern to you doesn't mean it's unimportant.
It looks like about 4 kg of plutonium-238 is required for a Mars Rover type mission. (Inferred from wikipedia article)
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You do know that the vast majority of the US nuclear stockpile is Plutonium-based weapons, right?
Plutonium takes far less material to create a critical mass, which makes for a lighter weapon. A lighter weapon means you don't need a big-dick huge fucking rocket to put the thing where you want it to be, and instead can use smaller rockets and missiles for deployment. And, if you aren't under the microscope, making Plutonium is easier than separating an ass ton of U235 from an even bigger shit ton of U238 through gaseous diffusion in a centrifuge cascade.
The answer is (E) all of the above.
The modern bombs have a plutonium core that sets off a fusion component, and that sets off a uranium shell. Most of the mass and maybe half the power comes from the uranium.
The problem with pure uranium bombs is that they use the gun type ignition which has a huge problem with possible accidental explosion in a plane crash.
The process described starts with a solid Neptunium-237 oxide, mixes it with Aluminum, presses it into pellets, irradiates it, chemically separates the Plutonium-238, and then processes it back into a solid oxide. They don't say where the Neptunium itself comes from, other than mentioning an existing inventory. It can be recovered from spent fuel, using another convoluted process starting with solid oxides.
Creating 237Np would be a far more direct process with a LFTR, where the 2% of the fuel which does not fission mostly finds its way to be this very isotope. (The remainder become short-lived fission products.) Naturally, processing a liquid is easier than going through multiple solid oxide steps, and lends itself to a continuous process capable of producing 238Pu in volume. It would be far more interesting if ORNL were developing the processes for this instead.
So, where do I download these "Gay Widget Devices"? Do you make an app? Or for the desktop?
A not so minor point which deserves mention: the Pu-239 must be >90% pure for weapons. Reactor grade plutonium from spent fuel is absolutely useless for weapons. The only practical method of creating it is to briefly expose U-238 to a neutron flux, separate the Pu-239 out, and repeat many times, which requires a specialized reactor. Pu-239 can't just be pulled out of spent fuel; the plutonium isotopes are too close in mass to make isotopic separation viable.
It does make sense though. I was assuming by "thermal-electric" generator that a heat engine was involved in the process with a reverse Peltier method.
In general, nuclear (be it fission, elements for radioactive decay, etc) is to be way underused, just due to the sheer and unwarranted fear of it. Yes, it has its dangers, but if used right, it can solve a lot of the world's major problems. It doesn't suffer fools gladly... but neither did steam energy, nor early internal combustion prototypes.
Let's not get carried away into orgasms of hyperbole. The critical mass of fissionable is not the governing determinant of the weight of the weapon. For U-235, the critical mass of a simplistic untamped sphere is 52 kg; for Pu-239 it is 9 kg. Yet the U-235 gun-type little boy weighed 4040 kg, while the Pu-239 implosion-type fat man weighed 4680 kg. Both were about 15 kt yield. The plutonium weapon actually weighed more, as well as being a more unwieldy shape, despite the uranium weapon having to incoporate a heavy gun inside.
It is all the other crap that made up 98+% of the weight.
Nowadays all the nuclear weapons that amount to anything in the major powers' inventory are fission-fusion or fission-fusion-fission, and the weight is determined by intricate, very sophisticated and clever detail design. The highest yield weapons the US ever produced, 25 Mt, retired 40 years ago, weighed about the same as the Hiroshima bomb. Most of the vastly reduced remaining US nuclear weapons inventory is no more than about 500 kt. There is nothing at all left above 1 Mt and change.
Assuming they know more about nuclear materials than some Slashdot anonymous coward, which is likely, they won't give a shit because they'll know that this is the kind of plutonium you build space probes from, not the kind you make nuclear weapons from. 238 is not 235.
God dammit, self, if you're going to make a pedantic post, don't screw it up or the other pedants will eat you. Pu-238: good for spacecraft, bad for bombs. Pu-239: Good for bombs, bad for spacecraft.
Interesting facts.
PU-238 is hard to make.
AA batteries are easy to make.
Hamsters make themselves.
PU-238 is clearly the least practical solution of those mentioned. :)
AA batteries are toxic and the chemicals used to manufacture them are toxic.
Same with solar-electric, household bleach cleaners, etc.
Phosphoric acid (coca-cola) is corrosive AND quite bad for you.
You can't just walk into an Apple store... and buy Plutonium.
I appreciate the alllusion to the joke in back to the future about plutonium un drug stores....
BUT
Apple Store? Seriously? Since when are their battery replaceable?~
(The fact that you can buy plutonium 238 to replenish your RTG cell is justified the same way that you can't just buy a fresh LiPo once you current one gets too old).
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
Pu-238 = great source of heat, not a great source of boom.
Pu-239 = great source of boom, not a great source of heat.
Pu-240, Pu-241 = not a great source of boom or heat.
It's not just that Pu-238 is hot, it's also that it has really benign decay characteristics. It's an alpha emitter (alpha particles are very easy to block and convert to head without getting X rays) and decays to U-234. That's got a much longer half-life (200,000 years) and is also an alpha emitter, and decays to Thorium 230. That's got a moderate half life (75,000 years) and is amazingly also an alpha emitter. That mostly decays (fairly quickly) to Radium 226 via yet more alpha decay. And so on.
It eventually winds up at Polonium 210 which is the first gamma emitter in the decay chain. It's a rare gamma emitter (1 in 100,000 events), and is going to be rate limited by the half-life of U-234 most strongly, as that's the longest half life in the decay chain.
IOW, a chunk of Pu-238 emits very very few gamma rays, and only a bit of beta particles (beta particles can cause X rays to be emitted). The vast majority of the emissions are easy to block alpha particles. That combined with the high power output makes it ideal for space faring RTG since little heavy shielding is needed.
Also, it can be generated in a way that makes little nearby, unwanted isotopes which makes chemical extraction of the stuff reasonably efficient.
SJW n. One who posts facts.
Alpha decays emit plenty of gamma rays too, as the decaying nucleus rarely drops right into the ground state of the daughter nucleus. It is why gamma rays spectroscopy is so useful for identifying isotopes, even when looking at alpha decays. It might not be the 1+ MeV gammas you get off more notable gamma decays, so the total absorbed dose it can produce is typically lower, buy if you are going to complain about x-rays from ionizing processes, it is more significant than that.
The difference though, is that when steam and ICE failed to suffer a fool, it was only the fool and possibly a few bystanders that were harmed. When a nuclear power source fails to suffer a fool, you've generally got some nasty environmental contamination on your hands, and it's unlikely that anyone is going to be willing to clean it up even if they are able. Fukushima springs to mind, but even a plutonium pacemaker that doesn't get removed before cremation is going to be a nasty little local issue. Not too bad on its own, but multiply it by millions of fools and you could have a serious problem on your hands.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Why do you think that?
Hint, this is the pinnacle of peaceful nuclear usage, not something that can be used for weapons.
APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
Just to add, we actually want smaller weapons. It's a matter of efficiency. Since the blast energy dissipates volumetrically (r^3) and we are interested in inflicting damage to the surface of the Earth (r^2), smaller weapons more efficiently attack a surface. We initially had big ones because our aim was so bad that the weapons had to be big to ensure they hit anything.
Actually, from Wikipedia https://en.wikipedia.org/wiki/...
Little Boy yield - 13-18 kt TNT
Fat Man yield = 20-22 kt TNT
Given that they were some of the first nuclear weapons ever made, I'm guessing those are ranged estimates rather than tunable yields, meaning that Fat Man had somewhere between 11% and 70% higher yield for that 16% greater mass.
We're also talking about early bomb designs that were very much proof-of-concept weapons. I suspect that later weapons, especially tactical nukes, are considerably more refined.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Wrong, plutonium from spent fuel is where plutonium for nuclear weapons came. my you are confused.
no, go look it up. Neither or the US bombs were efficient at all, and one was very nearly a fizzle. The total amount of material that underwent fission (including both bombs) was on the order of 1 - 5 GRAMS if I've got it right.
Mars-2020 and Europa-2025 have dibs on two of the missions. And you have to decide many years in advance which power source to use.
Jupiter is border line solar. Most of its probes have been nuclear. But Juno due to arrive shortly has 180 feet of solar panels. Juno is designed to last only a short time because it is flying through Jupiters highly toxic geomagnetic fields to study them.
I recall NASAs supply partly came from decommissioned Soviet warheads. But that process is now over.
"Let's splurge. Bring us some fresh Plutonium-238, the freshest you've got - this year's - no more of this old stuff"
even numbers of neutrons and protons are also bad from very low fission cross section. They tend to absorb the neutron rather than split.
If information wants to be free, why does my internet connection cost so much?
Actually Pu238 doesn't fission spontaneously. Fission typically refers to the fragmentation of the nucleus into two roughly equal-sized fragments, which thanks to the lower nucleon mass (=higher binding energy) at lower nucleon counts, multiplied by the large number of nucleons involved, results in considerable mass loss and a correspondingly large energy release.
In contrast Pu238 undergoes alpha decay, where it ejects just four nucleons as an alpha particle (helium 4 nucleus), only very slightly reducing the per-nucleon mass in the original nucleus, and actually considerably increasing the mass of the ejected nucleons. (https://en.wikipedia.org/wiki/File:Binding_energy_curve_-_common_isotopes.svg Binding energy peaks at Fe56 (per-nucleon mass is at a minimum), and any transmutation towards 56 nucleons results in mass loss equivalent to the change in binding energy * number of nucleons. As you can see He4 is actually an anomalous peak all by itself, if it wasn't then alpha emission would shed many times as much energy, and probably be far more uncommon.)
I suspect it's also not used in nuclear weapons or reactors because it's not fissile (it won't fission under slow neutron bombardment). Typically fissile isotopes have an odd number of neutrons, causing them to gain considerably more excess energy (1-2MeV IIRC) when absorbing a neutron due to neutron pairing, which makes the resulting nucleus far less stable and more likely to fission. Without that, causing fission requires hitting the nucleus with a neutron going fast enough to destabilize it through kinetic energy alone.
Finally, I suspect Pu238 is also also not used in weapons or reactors because it doesn't emit neutrons - and without neutron emission there can be no critical mass, no chain reactions, and no shortcuts to fission.
Basically, Pu238 totally sucks as a fission fuel, but makes an awesome candidate for RTGs, as explained by serviscope_minor.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Why don't you cite that if you are so certain? If you twist the definition of "spent fuel" or "reactor grade", it might be true in the loosest sense, but you are clearly being deceptive. Your "spent fuel" came from a reactor like an RBMK, that allowed one to process the fuel rods as described, but it is impossible in typical power reactors which are sealed. After the fuel has been in a reactor for a single fueling cycle, the isotopic mix makes weapons impossible, and all of the spent fuel sitting in cooling ponds and dry casks around the world fall into this category.
Yes, plutonium from spent fuel, at a very high level, is where the plutonium for weapons came from.
What you're not saying, and the GP did, is that the 'spent' fuel wasn't actually spent, because it was only in the reactor for a very short (and uneconomical) time so that the U238 captured a neutron to become U239, then decayed to Pu239. You leave it in too long, it captures another neutron and becomes Pu240, which ruins the plutonium for weapons purposes.
Any commercial reactor fuel rods that are being reprocesses are going to have way too much Pu240 and Pu241 to be of any use for weapons. The operator is going to keep the fuel in the reactor as long as they can, because that's the most economical way to create electricity. Creating weapons-grade Plutonium requires very short cycles in order to get the purity required to not have the weapon fizzle.
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And? Sorry I don't see how that's relevant. Yes, most nuclear weapons (and reactors) have frankly *horrible* conversion rates in the single digit range. Knowing that, you can either work to increase the conversion efficiency (hence things like fission-fusion bombs where the fusion primarily provides a rich neutron source for further fissioning), or increase the fissile payload. Neither is directly relevant to the yields of plutonium versus uranium weapons, though I'll concede that the ease of enhancing conversion rates may vary between them.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
two thirds the pu in commercial "spent fuel" is pu-239 and it IS recoverable
oh, and what of reprocessing of commercial nuclear fuel to make MOX in United Kingdom, France, Russia, India and Japan?
Progress involves risk, and it's space or nothing.
no, go look it up. Neither or the US bombs were efficient at all, and one was very nearly a fizzle. The total amount of material that underwent fission (including both bombs) was on the order of 1 - 5 GRAMS if I've got it right.
You don't have it right. Each bomb fissioned about 1 kg of material, for the Fat Man this makes it about 20% efficient. That is pretty good for a first design. Fission bombs are generally no more than 50% efficient, usually less.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Cool, ready for a movie plot :)
Pu-238 is not used in weapons specifically because it fissions too fast spontaneously. That's why it makes so much heat.
No, it makes so much heat because it undergoes alpha decay with an 87.77 year half-life. Its half-life for spontaneous fission is 47.7 billion years, so for each fission it produces 500 million alpha decays. Only 0.00001% of the heat is from fission. It would be a whole lot less useful if it were producing all that heat from fission since it would be similar to a nuclear reactor and the extremely intense neutron flux would require very heavy shielding.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Well, you could probably attach it to a stick and hit people with it. I mean, if we're going to be pedantic here (and we ARE - it's what we do) then it can be used for weapons. It just probably won't be a very effective weapon. They should cover a thin layer with a chicken-wire reinforced ceramic. I can put it at the end of my bed to keep my feet warm or maybe have varied amounts so that I can use one as an "always" on teapot heater.
This is also why they don't let me near any of the stuff. However, I'd buy those products. Sure, a stray (very rare) beta or gamma gremlin might come out and try to cause harm but they're seldom occurring, unlikely to actually cause any harm, and I probably have greater risks from things I already do such as leaving the house while the Sun is shining.
"So long and thanks for all the fish."
Actually Pu238 doesn't fission spontaneously.
Yes it does. The half-life for this mode of decay is 47.7 billion years, a pretty low rate but sufficient to get 2200 neutrons a second from each gram.
Starships were meant to fly, Hands up and touch the sky - Nicky Minaj
Pu240 and 241 are just fine in a reactor. They are not in a weapon. Thus "reactor grade" plutonium being less than 20% Pu-239, and "weapons grade" plutonium being greater than 93% Pu-239.
Reprocessing commercial fuel to make MOX is just fine.
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Most of the reactors built to produce plutonium in the US did not generate electricity. Their sole purpose was to produce plutonium, and everything else (IE many gigawatts of heat that could theoretically have been used for power-generation) was a waste product. IMO it's extremely misleading to refer to such a source as "spent fuel", because it implies that a typical nuclear power station's spent fuel (IE the waste byproduct of electrical power generation) could be used as a source of weapons-grade plutonium.
IMO it's sort of like describing orange juice as coming from "spent oranges". Yes, you have to "spend" oranges to make orange juice, but you're not going to get any substantial amount of usable orange juice from oranges that have already been "spent" in some other way.
Apparently the Russians built a number of dual-purpose reactors, so maybe the claim makes more sense in the context of that part of the world. I don't know how efficient such a system is, but AFAIK there was only ever one reactor in the US (the N Reactor at Hanford) that could produce both weapons-grade plutonium *and* electricity, and it was a political disaster (WPPSS).
"...always new atoms but always doing the same dance, remembering what the dance was yesterday." -Richard Feynman
Not even on the same level as production of Pu238