On Tue, May 20, 2014 at 12:30 AM, 'Chris de Morsella' via Everything List < everything-list@googlegroups.com> wrote:
> At the risk of re-starting the Thorium wars <grin> this is a current > article on the why NOTS of Thorium. It addresses them point by point. > > > http://thebulletin.org/thorium-wonder-fuel-wasnt7156<http://thebulletin.org/thorium-wonder-fuel-wasnt7156> > OK, point by point: > the United States has tried to develop thorium as an energy source for > some 50 years > They sure didn't try very hard! The United States did stick some Thorium into conventional reactors that were never designed for it and not surprisingly it didn't work out all that well. And there were a few very small molten salt thorium reactors made by Alvin Weinberg but they were no help in developing weapons because they produced no Plutonium so they were shut down long ago. Ironically Weinberg is the man who also invented the pressurized light water reactor we use today and he's the guy who encouraged Admiral Rickover to put them in submarines, but when they just scaled up his submarine design for huge commercial power plants he thought that was a dangerous move and believed his new idea, liquid Thorium salts, was a much better way to go. He was told that if he had doubts about his original invention it was time for him to get out of the nuclear business and he was fired. Today the amount of money spent on molten salt thorium reactors is the same as it's been for decades, zero. I think a larger number might be appropriate. > The first track was development of plutonium-fueled “breeder” reactors, > which [blah blah] > By there very nature all Uranium reactors produce Plutonium, and Plutonium breeders do so with gusto. But Plutonium has nothing to do with Thorium reactors, the amount of Plutonium they make is so small it's almost unmeasurable. > The second track—now largely forgotten—was based on thorium-fueled > reactors. > That's the problem, it's been largely forgotten for nearly half a century because Uranium reactors work well enough in submarines and Thorium reactors produce no Plutonium; that was considered a huge disadvantage in the 1950s and 60s but less so today. > By 1977, however, the government abandoned pursuit of the thorium fuel > cycle in favor of plutonium-fueled breeders > True, and I think that was a dumb move because Plutonium breeders scare the hell out of me. A breeder has a much higher energy density than a regular reactor and it uses faster neutrons so you have less time to react if something goes wrong, that means it's inherently more dangerous. A conventional reactor uses Uranium as fuel in which the U235 has been enriched from the naturally occurring .7% concentration to about 4%, you need about 85% to make a bomb. A breeder uses weapons grade plutonium as a fuel, and lots of it. Also, a conventional reactor uses water as a coolant and to slow down the neutrons, a breeder uses molten sodium that burns in the air and explodes in the presents of water. All Uranium reactors (but not Thorium reactors) produce plutonium, a big power plant reactor will invariably produce many tons of it in its lifetime. A breeder reactor is designed to maximize the production of plutonium but I don't think that's a very good idea. There is already so much of it in existence, thousands of tons, that it's very hard to keep track of it all. You only need slightly over 9 pounds to make a crude nuclear bomb, less if you're clever. > The first commercial nuclear plant to use thorium was Indian Point Unit > I, a pressurized water reactor near New York City that began operation in > 1962. Attempts to recover uranium 233 from its irradiated thorium fuel were > described, however, as a “financial disaster.” > So 1962 technology wasn't up for the job, is 2014 technology good enough? It certainly would be if a tenth as much money had been spent on Liquid Fluoride Thorium Reactor design as had been spent on Uranium reactor design. > The US Energy Department appears to have lost track of 96 kilograms of > uranium 233, a fissile material made from thorium that can be fashioned > into a bomb, > I can't get too excited about that, the USA Energy Department has also lost track of 5900 pounds of weapons grade U235 and Plutonium that it had shipped outside the USA, and both are far easier to make a bomb out of than U233. And besides, in a modern Liquid Fluoride Thorium Reactor (LFTR) the U233 is completely burned up inside the reactor so there is nothing to steal, unlike existing reactors where used fuel rods are shipped to reprocessing plants to extract the Plutonium. With a LFTR it never leaves the reactor building. And a regular reactor produces lots of neutrons but a LFTR makes less of them, so it needs all that U233 just to keep the chain reaction going, if you try stealing some the reactor will simply stop operating making the theft obvious. > Uranium 233 compares favorably to plutonium in terms of weaponization; > Baloney. No nation has Uranium 233 bombs in their stockpile or ever has and there is a reason for that. U233 is so hard to use in bombs it has only been attempted 3 times and only one was a pure U233 bomb. In 1955 the USSR set off a plutonium-U233 composite bomb and in the same year the USA did too, it was expected to produce 33 kilotons but only managed 22. The only pure U233 bomb ever made was set off by India in 1998 and it was a complete flop, it produced a miniscule explosion the equivalent of only 200 tons of TNT. As I said you can make a bomb out of U233 but its hard as hell, so with thousands of tons of easy to use Plutonium already produced and more made every day in conventional reactors, not to mention thousands of poorly guarded fully functional bombs in the former USSR, why would any self respecting terrorist bother with U233, especially when it's so hard to steal from a LFTR? > The cost of the project increased from $384 million to $473 million—or > more than $1 million per kilogram for the disposal of uranium 233. > Yep that sounds like our government at work, spending a million dollars to destroy a kilogram of U233, a kilogram that could supply as much energy (and no greenhouse gasses) as 3087 TONS of coal. Coal cost about $140 per ton so one kilogram (2.2 pounds) of U233 is equivalent to $432,000 worth of coal. > uranium 233 never gained wide use as a weapons material in the US > military because of its high cost, associated with the radiation protection > required to protect personnel from uranium 232, a highly radioactive > contaminant co-produced with uranium 233. > True. In a LFTR U-233 will always be contaminated with U232 which gives off such intense Gamma rays it would screw up the bomb electronics, degrade the chemical explosives needed to set off the bomb and probably kill the terrorist long before he was half finished making it. And even if the nausea, intense pain, skin peeling, and bleeding out of every orifice didn't break the terrorist's concentration and he did somehow manage to finish making it before he dropped dead the finished bomb would give off such intense Gamma rays it would be virtually impossible to hide. > Unlike plutonium, however, uranium 233 does not need implosion > engineering to be used in a bomb. > Perhaps true but nobody knows for sure because nobody has ever made a gun type (non-implosion) U233 bomb, if a terrorist made one he would be the first. In fact even a pure non-composite U233 implosion bomb has only been tried once, and it was a fizzle. And it's unimportant anyway, implosion technology may have been cutting edge 70 years ago during the Manhattan project but today any bright high school physics student could manage it, provided that the gamma rays from the impure U233 didn't kill him before he got to step 2. John McPhee's book "The Curve of Binding Energy" is all about how a amateur could make a nuclear bomb from Pu239 or U235 and it was written in 1973; but even the professionals have had great difficulty making a bomb from U233. > For a terrorist, however, uranium 233 is a tempting theft target > If I was a terrorist I wouldn't be tempted to build my own bomb, and certainly not with a material as exotic and hard to use as U233; instead I'd bribe a few Russian soldiers with a crate of Vodka who were guarding a shed containing a few of the thousands of surplus but fully functional H-bombs that country has in abundance. John K Clark -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
