Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
Power

Megatons To Megawatts Program Comes To a Close 125

Posted by Soulskill
from the time-to-make-some-gigascale-weapons dept.
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."
This discussion has been archived. No new comments can be posted.

Megatons To Megawatts Program Comes To a Close

Comments Filter:
  • Re:Misnomer (Score:5, Informative)

    by stoploss (2842505) on Wednesday January 29, 2014 @03:50AM (#46098145)

    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.

  • by nojayuk (567177) on Wednesday January 29, 2014 @05:52AM (#46098521)

    The pollution from coal waste is permanent, it never decays unlike nuclear waste. US coal-fired power generators pump 50 tonnes of mercury into the environment every year, it never goes away or decays, it ends up in water and the soil, in the sea and seafood. Nobody cares, any attempt to reduce these sorts of emissions is a "War on Coal".

  • by nojayuk (567177) on Wednesday January 29, 2014 @06:47AM (#46098687)

    That mercury WAS buried underground well away from the biosphere. Now it's been dug up, burned, vapourised and spread over cropland and towns and cities downwind, deposited into rivers and lakes supplying drinking water to the population before it eventually makes its way into the sea where it bioaccumulates in fish to the point where authorities recommend people don't eat too much of it because of the toxic mercury content.

    You might want to look up "sequestration" sometime.

  • by dbIII (701233) on Wednesday January 29, 2014 @06:48AM (#46098695)
    It's not a small amount - it's a long process and it's not just the depleted fuel that's a waste storage problem. Anything that gets bombarded with a lot of neutrons becomes nuclear waste itself, so. That's what the "nuclear is magic beans appearing in the reactor core" crowd don't get. That's why real solutions like Synrok were ignored for decades.
    The health problems start with water runoff in the mines (eg. acid mine drainage), just like a lot of other things. Nuclear is not magic just because it's nuclear.
    It's an industrial process that has impacts and benefits and has to be looked at that way instead of the stupid "clean" dream. We got over "duck and cover" and "too cheap to meter" - it's time to get over the "clean" propaganda as well.
  • Re:Misnomer (Score:5, Informative)

    by serviscope_minor (664417) on Wednesday January 29, 2014 @06:58AM (#46098727) Journal

    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.

  • by dbIII (701233) on Wednesday January 29, 2014 @07:40AM (#46098865)

    surely mining could be done carefully to avoid water runoff problems

    Maybe, but it's currently a problem at a lot of mines including some uranium mines (eg. yearly at the Ranger mine in Kakadu National Park in Australia).
    My point is that nuclear is not special just because it's nuclear - it has it's own downsides just like everything else. Minimising those is of course a very good thing but they still shouldn't be dismissed as irrelevant. For decades waste has been written off as irrelevant, and everything other than fuel rods swept under the carpet. We shouldn't do that.
    I'm also a fan of that sort of reactor concept (certainly beats reprocessing by a mile) even if liquid metal gives me the heebie-jeebies. Along those lines Russia has a large sodium cooled reactor planned which is related enough that it may assist with the technical problems likely to be associated with full scale liquid metal reactors

  • by necro81 (917438) on Wednesday January 29, 2014 @08:04AM (#46098945) Journal

    How do we know the US didn't just use it for their own weapons? I guess it says somewhere, perhaps the Russians did some 'inspection' things to make sure it was being used for power, along the lines of Iran

    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.

  • Re:Misnomer (Score:4, Informative)

    by LWATCDR (28044) on Wednesday January 29, 2014 @08:44AM (#46099189) Homepage Journal

    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.

Trying to be happy is like trying to build a machine for which the only specification is that it should run noiselessly.

Working...