Recycling Nukes
- Thread starter Golan2072
- Start date
Icosahedron
SOC-14 1K
It would need reprocessing to 'lower its octane rating' too. No idea on the economics though. I suppose it depends on the availability of old nukes and raw Uranium. It's unlikely to be used outside the TL6-8 range anyway. I can't see a 'clean' TL11 fusion society wanting to build a 'dirty' fission plant just to recycle its nukes - it would export them instead.
A TL11 society would need the nukes intact to blow away enemy ships anyway - no dampers are around yet. But I was thinking about pre-fusion (and pre-starflight, mostly) societies anyway...
Plankowner
SOC-13
Aren't most Nukes made with Plutonium? Most reactors use Uranium.
There are SOME that might cross-polinate, but usually, reactors are used to "breed" the plutonium for Nukes, not the other way around.
There are SOME that might cross-polinate, but usually, reactors are used to "breed" the plutonium for Nukes, not the other way around.
Icosahedron
SOC-14 1K
Some reactors use plutonium.
Both uranium and plutonium warheads can be fairly easily turned into reactor fuel; U-235 is simply diluted and winds up identical to nuclear fuel, Plutonium is mixed with natural uranium to produce what's called MOX fuel, which requires some minor adjustments in the reactor. Both processes are useful as ways of disposing of weapons-grade materials.
Kyle Aaron
SOC-10
Short answer: This is already done today. The US imports a lot of plutonium and enriched uranium from Russia from its old nuclear weapons programmes. To use more than just a little bit you need a specially-designed reactor, though.
Long answer: In nature we have "isotopes", these are versions of an element which are chemically the same but have a different nucleus. Some nuclei are stable, some are unstable, the unstable ones we call "radioactive", they break up over time and into other elements, releasing radiation of various kinds along the way.
This breakdown is how nuclear reactors and bombs work; you squash the radioactive isotopes together and the different pieces smash into each-other, and cause more breaking up. However, when little pieces hit stable isotopes, those stable isotopes absorb them - but as the process goes on, eventually the stable isotopes turn into unstable ones.
In uranium we have two main isotopes, U-238 (stable, 99.29% of natural uranium) and U-235 (unstable, 0.71% of natural uranium). To make a reactor work they take uranium and "enrich" it, bringing the proportion of U-235 up to 3-5%. To make a nuclear weapon they enrich it to 10+%.
In a reactor you normally have enriched uranium rods, something like 95% U-238 and 5% U-235. The U-235 breaks up and sends bits of itself everywhere, knocking into other U-235 atoms and breaking them up, and so on. This produces heat, the heat boils water into steam and the steam drive turbines which make electricity. But the U-235 breaking up also sends fragments into the U-238, some of these are absorbed and become Pu-239 - that is, plutonium.
Pu-239 is an unstable radioactive isotope, which means that it lets off a bit of radiation itself, and also that when fragments hit it, it's likely to "fission", that is to split, releasing a lot of energy. In a regular nuclear reactor something like a third of the total energy released comes from the plutonium being formed and breaking up in the reactor.
A nuclear weapon works the same way, except that they use more highly-enriched uranium, or plutonium. More highly-enriched means more reactions, and an "explosion" is just lots and lots of reactions happening very quickly, like the fizz gushing out of the lemonade bottle instead of being gently let off slowly.
So they take nuclear weapons material and dilute it down a bit and can use it in reactors. The highly-enriched uranium, something like 25% U-235 and 75% U-238, that's pretty easy, they just mix it with U-238 left over from a normal enrichment process. The Pu-239 is a bit harder, but they can still do it. As I said, a regular reactor has a bit of Pu-239 normally, so if you add some in it's okay. But if you add too much then the reactor burns too hot, so to speak. You can build a reactor designed to handle it, though.
And these have been built and work as well and safely as regular reactors (for what that's worth...)
Every year about 66,000 tonnes of uranium are processed to be put into reactors, and the reactors produce about 70 tonnes of Pu-239. In most countries this is called "nuclear waste", the Pu-239 is mixed with other stuff in the spent fuel rods. The other stuff it's mixed with is in fact what makes the fuel rod "spent", it slows down the reactions in the reactor. They can process this waste to take out the useful Pu-239 and remaining U-235 (most reactors don't burn very efficiently), but it produces a lot of other waste along the way, and fresh uranium is just cheaper and less hassle.
If they take highly-enriched uranium or plutonium from nuclear weapons, that messy dirty reprocessing has already been done years ago somewhere else. So they can take that stuff and produce a new fuel they call "MOX", for "mixed oxide". So it's actually easier to use old nuclear weapons for fuel than it is to reprocess spent fuel rods.
As a response to Golan2072, in most cases it's not necessary to sacrifice material from nuclear power to get it for weapons. That's because any nuclear power programme of significant size will give you tonnes of enriched uranium (which if you can enrich it, you can enrich it highly for weapons, too - thus the drama about Iran's enrichment, will they stop at 3-5%?) or of plutonium, and you only need several kilograms for a weapon. A small research reactor like the North Korean one or Israel's Dimona can give you material for several nuclear weapons a year, but conventional power reactors can give you material for dozens each year.
Long answer: In nature we have "isotopes", these are versions of an element which are chemically the same but have a different nucleus. Some nuclei are stable, some are unstable, the unstable ones we call "radioactive", they break up over time and into other elements, releasing radiation of various kinds along the way.
This breakdown is how nuclear reactors and bombs work; you squash the radioactive isotopes together and the different pieces smash into each-other, and cause more breaking up. However, when little pieces hit stable isotopes, those stable isotopes absorb them - but as the process goes on, eventually the stable isotopes turn into unstable ones.
In uranium we have two main isotopes, U-238 (stable, 99.29% of natural uranium) and U-235 (unstable, 0.71% of natural uranium). To make a reactor work they take uranium and "enrich" it, bringing the proportion of U-235 up to 3-5%. To make a nuclear weapon they enrich it to 10+%.
In a reactor you normally have enriched uranium rods, something like 95% U-238 and 5% U-235. The U-235 breaks up and sends bits of itself everywhere, knocking into other U-235 atoms and breaking them up, and so on. This produces heat, the heat boils water into steam and the steam drive turbines which make electricity. But the U-235 breaking up also sends fragments into the U-238, some of these are absorbed and become Pu-239 - that is, plutonium.
Pu-239 is an unstable radioactive isotope, which means that it lets off a bit of radiation itself, and also that when fragments hit it, it's likely to "fission", that is to split, releasing a lot of energy. In a regular nuclear reactor something like a third of the total energy released comes from the plutonium being formed and breaking up in the reactor.
A nuclear weapon works the same way, except that they use more highly-enriched uranium, or plutonium. More highly-enriched means more reactions, and an "explosion" is just lots and lots of reactions happening very quickly, like the fizz gushing out of the lemonade bottle instead of being gently let off slowly.
So they take nuclear weapons material and dilute it down a bit and can use it in reactors. The highly-enriched uranium, something like 25% U-235 and 75% U-238, that's pretty easy, they just mix it with U-238 left over from a normal enrichment process. The Pu-239 is a bit harder, but they can still do it. As I said, a regular reactor has a bit of Pu-239 normally, so if you add some in it's okay. But if you add too much then the reactor burns too hot, so to speak. You can build a reactor designed to handle it, though.
And these have been built and work as well and safely as regular reactors (for what that's worth...)
Every year about 66,000 tonnes of uranium are processed to be put into reactors, and the reactors produce about 70 tonnes of Pu-239. In most countries this is called "nuclear waste", the Pu-239 is mixed with other stuff in the spent fuel rods. The other stuff it's mixed with is in fact what makes the fuel rod "spent", it slows down the reactions in the reactor. They can process this waste to take out the useful Pu-239 and remaining U-235 (most reactors don't burn very efficiently), but it produces a lot of other waste along the way, and fresh uranium is just cheaper and less hassle.
If they take highly-enriched uranium or plutonium from nuclear weapons, that messy dirty reprocessing has already been done years ago somewhere else. So they can take that stuff and produce a new fuel they call "MOX", for "mixed oxide". So it's actually easier to use old nuclear weapons for fuel than it is to reprocess spent fuel rods.
As a response to Golan2072, in most cases it's not necessary to sacrifice material from nuclear power to get it for weapons. That's because any nuclear power programme of significant size will give you tonnes of enriched uranium (which if you can enrich it, you can enrich it highly for weapons, too - thus the drama about Iran's enrichment, will they stop at 3-5%?) or of plutonium, and you only need several kilograms for a weapon. A small research reactor like the North Korean one or Israel's Dimona can give you material for several nuclear weapons a year, but conventional power reactors can give you material for dozens each year.
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Measured against how many coal miners die in accidents, mine collapses and fires, nuclear energy is pretty damn safe.
Nice summary though.
Kyle Aaron
SOC-10
Not something I'd comment on in this particular forum. We're here to talk about the roleplaying possibilities rather than being advocates of this or that.
PS: an Aussie, especially a Melburnian gamer ought to go to GameCircle.org to register!
PS: an Aussie, especially a Melburnian gamer ought to go to GameCircle.org to register!
I was thinking about a world without natural uranium deposits - a world which usually has to import fissile material. So once interstellar trade declines (Hard Times), they won't have much fuel to run the reactors in the first place - so they'll start cannibalizing nukes.
Such a world is unlikely to have a large supply of nukes in the first place.
Kyle Aaron
SOC-10
They'd have some trouble with the weapons approach if they have no natural uranium, because what's done currently is to take the highly enriched uranium from weapons (usually 20-90% U-235, the rest U-238) and mix it with ordinary mined uranium (0.71% U-235 and 99.29% U-238) to end up with regular fuel rods (2-5% U-235, rest U-238). Sometimes they'll use plutonium in place of the U-235, making the MOX fuel as I noted earlier.
So if they've no source of uranium ore, then their only U-238 to mix the weapons material with is spent fuel rods. So then they get into having to reprocess those, and that's a very dirty business, you need heaps of chemicals and produce a large volume of radioactive waste (instead of a small volume of very radioactive waste, ie spent fuel rods, they have a large volume of somewhat radioactive waste, ie acids used in the thing, etc).
World stockpiles of weapons-grade plutonium are around, if I recall correctly, 250 tonnes. If every one of the 450 or so reactors in the world were adjusted to use MOX, it'd keep them going for a year or so. The Russians have got 500 tonnes of highly-enriched uranium which if blended with ordinary uranium could make about 15,000 tonnes of fuel rods, equivalent to about 150,000 tonnes of ordinary uranium - and the world currently uses about 66,000 tonnes annually.
So basically all these decommissioned Russian and US weapons, about 10,000 of them, plus stockpiled material for another 20,000, give you 30 months or so... and that's with about a sixth of world electricity use coming from nuclear - or all the electricity for 1 billion people. So you could make a rule of thumb that each 1,000 nuclear weapons will make electricity for 1 billion people for one month. Or 1 nuclear weapon for 1 million people for one month - though naturally the approximation doesn't hold for under 20 or so nukes, since reactors have 18 month fuel cycles.
Basically, it's as I said - the mass of stuff going through the power plants is just huge compared to what you need even for an utterly insane number of nuclear weapons.
There also exist "breeder" reactors, basically the idea is to work hard to turn the U-238 into Pu-239. They're pretty difficult to make work very well, but potentially they could essentially triple the longevity of your uranium supply.
There also thorium reactor designs, but presumably if your planet has no uranium it'll have no thorium, either. And anyway thorium reactors need plutonium as a sort of seed - about as much as is needed for a weapon, by coincidence...
So I can't really see weapons as fuel as more than a stopgap measure for a place with no natural uranium source. They'd have to drastically reduce their electricity use, or else just use the method to buy time while working on some other method of power generation like solar.
Though of course there could be exceptions, like if you had some asteroid mining and naval base powered by a reactor and absolutely loaded with nukes... though they'd need some snazzy labs and factories for it all.
To be honest, with the ready availability of cheap fusion power running of hydrogen (processed water) at TL9 and the disposal issues for fission fuel(mostly political and cost vs fusion), very few worlds at TL9 or above will not be using fusion.
If we have a TL9+ world falling back down the TL levels in hard times, and they have no natural uranium, they would probably attempt another source of power. Fission plants will take 5 years to build (assuming you have built one before and are using a standard design), and the reprocessing facilities will take a similar amount of time. All that effort to get a couple of years of power doesn't make much sense.
If it was a small outpost, they could use the heat from the natural decay of the wardhead to generate small amounts of heat and electrical power (as per NASA on their long range space probes).
Also don't forget with cheap fusion, fission becomes a bit of a technological dead end. How many people on your world will even think to consider it
Cheers
Richard
If we have a TL9+ world falling back down the TL levels in hard times, and they have no natural uranium, they would probably attempt another source of power. Fission plants will take 5 years to build (assuming you have built one before and are using a standard design), and the reprocessing facilities will take a similar amount of time. All that effort to get a couple of years of power doesn't make much sense.
If it was a small outpost, they could use the heat from the natural decay of the wardhead to generate small amounts of heat and electrical power (as per NASA on their long range space probes).
Also don't forget with cheap fusion, fission becomes a bit of a technological dead end. How many people on your world will even think to consider it
Cheers
Richard
