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Megatons To Megawatts Program Comes To a Close
necro81 writes "In the aftermath of the Cold War, the disintegrating Soviet Union had tens of thousands of nuclear weapons and tons of weapons-grade fissile material. In the economic and political turmoil, many feared that it would fall into unfriendly hands. However, thanks to the doggedness of an MIT professor, Dr. Thomas Neff, 500 metric tons of weapons grade material made its way into nuclear reactors in the United States through the Megatons to Megawatts program. During the program, about 10% of all electricity generated in the U.S. came from weapons once aimed at the country. Now, after nearly 20 years, the program is coming to an end. The final shipment of Soviet-era uranium, now nuclear fuel, has arrived in Baltimore."
Sadly, nuclear power is dying due to ignorance. Coal kills thousands (maybe 15+) in the US alone every year, and tens to hundreds of thousands worldwide every year. Yet what do we hear in the news? Fukushima. Where you can count the death toll with 0 fingers, and even in 50 years it'll be less than coal kills in the US in a single year.
You can argue that Coal is a false choice (it isn't, it's what we have now) but even natural gas kills an order of magnitude or more people yearly than nuclear power, and yes _Solar_ kills more people.
I think the point is that the fuel is being aimed at us again.
With computers, we have good and bad CPU designs, good and bad GPU designs, good and bad OS designs.
Like computers, nuclear power plants come in many designs, some good and some bad. Watch this and learn a bit more, especially about the Integral fast reactor design.
I'm all for green power, but let's not forget that right now solar panels are not terribly efficient and very resource-intensive during the manufacturing process, wind farms don't work without wind (duh) and kill birds, etc. Each choice has drawbacks and from the numbers given in this film, if they are accurate, we'd be insane not to use nuclear power plants as long as they're IFR-type.
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The warheads were only Megatons because they were fusion weapons.
We only used the fission trigger part to generate power'
Your pedantry is misplaced: your error is thinking of the warheads individually.
Instead, there were ~20k nuclear warheads worth of HEU involved (500 metric tons). Since even the inefficient gun-type Little Boy weapon had an estimated yield of 15 kt for 64 kg of HEU, the program represents a minimum of 120 megatons worth of yield—even falsely presuming they couldn't achieve better yields with that HEU than using a gun-type weapon approach.
The program's name is perfectly cromulent.
The US has a large stockpile of weapons-grade material (U-235 and also Pu-239) from decommissioned nuclear weapons produced in the 1960s when it had over 30,000 weapons ready for use. It now has about 5000 warheads, most in reserve (i.e. not ready for immediate use or kept as "junk box" units that could be refurbished given the need, will and funding). The ready-for-use warhead count is about 2,200 or so.
They don't need to divert this ex-Soviet material to make more weapons, they don't need more weapons, they don't have the launchers and platforms to carry more weapons and they don't have the facilities or funding to pay for new weapons to be built and besides the uranium arriving in America has already been downblended to fuel-level enrichment (probably 4 or 5%) from the original 90% or so of the original weapon cores.
That's how we know the US didn't use it for their own weapons.
The warheads were only Megatons because they were fusion weapons.
No, this is a common misconception.
A basic nuke compacts a lump of (e.g.) plutonium to above the critical mass using convential explosives. The momentum caused by the explosives holds it together while the chain reaction grows exponentially. Eventually it flies apart, generally before the fission fuel is used up because the explosives don't hold it together very long.
You can introduce fusion by hollowing out the pit and filling it with tritium, giving a boosted fission bomb. That boosts the power a bunch (yay!).
However, the thing to note is nuclear explosions are much bigger than conventional ones, and if a conventional explosion is good at holding the fissile material together, then a nuclear one ought to be much better, and it is.
So basically, you pack lithium deuteride around another fissile pit. When the nuke goes off, it irradiates the deuterium creating tritium and compresses the second pit giving another nuclear explosion. It's a much more efficient one second time since it's held together longer and you also have much more tritium, so both the fusuion and fission but yield a lot more energy.
At this point you have two relatively small fission explosions, one mid sized fusion one and one large fusion one. Most of the energy comes from the fusion. It's also relatively clean in that the amount of nasty byproducts to energy ratio is low.
The logic continues. It a small fission explosion is really good at compressing, then a large fusion/fission one ought to be REALLY REALLY good. A third stage can therefore be added (allegedly this is not usually the case).
But it still doesn't usually end there. The nuclear reactions yield what is technically known as an ass-load of neutrons. If you wrap the entire thing in natural or even depleted uranium, the neutrons cause it to undergo fission. Lots of fission. It's generally thought that this stage more than doubles the yield and comes at next to no extra cost, size or weight (the bomb has to have some sort of heavy casing anyway).
Anyway, that's a summary of the wikipedia article and a few other bits and bobs.
TL;DR in most cases a bit over half of the energy comes from fission.
SJW n. One who posts facts.
The highly enriched, weapons grade, bomb ready uranium was not shipped as is. Instead, it was diluted with natural or depleted uranium first, and that is what got shipped to the US. I suppose it is possible that it went from there to a U.S. weapons lab, re-enriched from fuel grade to weapons grade, and then made into weapons. Basic economics, however, suggests otherwise:
1) Uranium is a commodity, like a lot of other metals, and the amount that is produced and consumed each year is known. Mismatches in supply and demand affect the price of uranium on the open market - a price that is closely watched like other commodities. If there was diversion away from fuel processors and power plants and into the U.S. arsenal, that would be a pretty obvious signal. (There was a spike in the uranium markets in 2007, but there are more prosaic explanations for that, and it came about 13 years into the Megatons To Megawatts program.) The U.S. military has no shortage of uranium available to it, particularly as it dismantles its own arsenal.
2) Nuclear weapons production is a massive undertaking - in terms of cost and very-specialized-and-not-easily-hidden infrastructure. If the U.S. were taking the Soviet fuel and making new weapons from it, that could not be hidden, just like the original build up during the Cold War could not be hidden. Secret, yes, but not hidden.
And, yes, inspection and verification was a part of the program. And unlike Iran, the U.S. (civilian) nuclear program makes itself available to the inspectors of the IAEA. A large diversion of incoming uranium away from fuel processors and power plants would be pretty obvious - the numbers wouldn't add up. I find it difficult to believe that hundreds of tons of highly enriched uranium (and many times that of fuel-grade uranium) could have been made to disappear from the civilian fuel cycle without somebody noticing. The dismantlement of the U.S nuclear arsenal was verified by Russia, just as we verified theirs.
You are nitpicking but also wrong.
Even thermonuclear weapons get most of there yield from fission. The fusion reaction is mainly a neutron producing event that then goes on to fission the tamper made of natural uranium. That is how variable yield weapons work. You adjust the amount of tritium boost gas you inject in the triggers pit.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.