Quote from: gospacex on 04/27/2017 07:55 amQuote from: Stormbringer on 04/27/2017 06:59 amI think you would be right about that except for the peculiarities of the cycles. the thorium/u233 one can be done on the fly (I think.) I think i recall that the Thorium U233 cycle is safer environmentally and also from a proliferation perspective because you could make U233 at the burn rate for the reactor so there never was much of it at any one time and the uranium was unsuitable for practically sized fission or fusion bombs.That's wrong - there would be more than enough U233 to build a bomb. Reactors have hundreds of tons of fuel in them. 1% burnup of thorium in such a reactor would yield some ~1 ton of U233 - enough for a hundred nukes.The problem (for bomb makers, that is) is that thorium reactors also generate U232, which has very undesirable radiological properties, contaminating that U233.U233 is a strong gamma-radiator, which makes it too deadly for anyone to isolate into a bomb and carry around.
Quote from: Stormbringer on 04/27/2017 06:59 amI think you would be right about that except for the peculiarities of the cycles. the thorium/u233 one can be done on the fly (I think.) I think i recall that the Thorium U233 cycle is safer environmentally and also from a proliferation perspective because you could make U233 at the burn rate for the reactor so there never was much of it at any one time and the uranium was unsuitable for practically sized fission or fusion bombs.That's wrong - there would be more than enough U233 to build a bomb. Reactors have hundreds of tons of fuel in them. 1% burnup of thorium in such a reactor would yield some ~1 ton of U233 - enough for a hundred nukes.The problem (for bomb makers, that is) is that thorium reactors also generate U232, which has very undesirable radiological properties, contaminating that U233.
I think you would be right about that except for the peculiarities of the cycles. the thorium/u233 one can be done on the fly (I think.) I think i recall that the Thorium U233 cycle is safer environmentally and also from a proliferation perspective because you could make U233 at the burn rate for the reactor so there never was much of it at any one time and the uranium was unsuitable for practically sized fission or fusion bombs.
is it possible to create Safe-A, Sage-B, Safe-C by-products of fuel from {Whatever the Safest Thorium} is available?
No, U233 is ok.That's U232. It is a strong gamma-emitter. To be more precise, it has relatively short half-life of 69 years and even though it decays by alpha, all daughters are even more short-lived and you end up having Pb212 and later Tl208, which are beta-active.
But thorium can only be used as a fuel in a breeder reactor. If you're going to have a breeder reactor, you can use uranium-238. Uranium-238, like thorium isn't radioactive and can't itself be used as a nuclear reactor fuel. But it can be hit with neutrons to make a radioactive isotope that can be used as nuclear reactor fuel, just like thorium.
Quote from: ChrisWilson68 on 04/27/2017 06:18 amBut thorium can only be used as a fuel in a breeder reactor. If you're going to have a breeder reactor, you can use uranium-238. Uranium-238, like thorium isn't radioactive and can't itself be used as a nuclear reactor fuel. But it can be hit with neutrons to make a radioactive isotope that can be used as nuclear reactor fuel, just like thorium.I think you mean 'fissile' instead of radioactive; all isotopes of both uranium and thorium are radioactive (though some of them only weakly).
Would thorium reactors in space be more "politically correct"? For instance deep space human spacecraft beyond Mars requiring a lot of power that solar cannot give. Or thorium reactors on Mars for night power production or continuous production in event of dust storms. Or large NEP spacecraft that would be smaller than a large SEP spacecraft due to the huge amount of solar panels.
In the early days of the start of the nuclear age there were many types of fuel and reactor designs being considered and tested. Most were flops. In the end it came down to a choice between two fuels; Thorium and Uranium. Both fuels have impressive lists of advantages and disadvantages. Both fuels ran reactors for hundreds of thousands of hours with no problems. In the end it came down to uranium having a single insurmountable advantage over thorium. One needs to consider the context of the times to really understand this but it was a really, really big deal to the United States at the time. The real reason we use uranium over thorium is a result of wartime politics. Cold War-era governments (including ours) backed uranium-based reactors because they produced weapons-grade plutonium —for atomic bombs and icbm warheads. Thorium powered reactors could only produce electricity – no bombs. Every other issue mentioned here is an unimportant aside detail.
Quote from: clongton on 04/27/2017 04:45 pmIn the early days of the start of the nuclear age there were many types of fuel and reactor designs being considered and tested. Most were flops. In the end it came down to a choice between two fuels; Thorium and Uranium. Both fuels have impressive lists of advantages and disadvantages. Both fuels ran reactors for hundreds of thousands of hours with no problems. In the end it came down to uranium having a single insurmountable advantage over thorium. One needs to consider the context of the times to really understand this but it was a really, really big deal to the United States at the time. The real reason we use uranium over thorium is a result of wartime politics. Cold War-era governments (including ours) backed uranium-based reactors because they produced weapons-grade plutonium —for atomic bombs and icbm warheads. Thorium powered reactors could only produce electricity – no bombs. Every other issue mentioned here is an unimportant aside detail.False. The plutonium produced in power plants is unsuitable for use in nuclear weapons. Both the United States and Soviet Union produced all their weapons-grade plutonium in special reactors built just for the purpose of making weapons. For the United States, it all came from Savannah River or Hanford. All the plutonium produced by power plants is either buried as waste or reprocessed into more reactor fuel.The decisions to go with uranium over thorium for power reactors had nothing to do with nuclear weapons.
The connections linking nuclear power and weapons is more than political or historic. Consider: l FISSIONABLE MATERIALS: It is the same nuclear fuel cycle with its mining of uranium, milling, enrichment and fuel fabrication stages which readies the uranium ore for use in reactors, whether these reactors are used to create plutonium for bombs or generate electricity. In the end, both reactors produce the plutonium. The only difference between them is the concentration of the various isotopes used in the fuel. Each year a typical 1000 mega-watt (MW) commercial power reactor will produce 300 to 500 pounds of plutonium -- enough to build between 25 - 40 Nagasaki-sized atomic bombs.As Dr. Amory Lovins, director of the Rocky Mountain Institute in Colorado points out, "Every known route to bombs involves either nuclear power or materials and technology which are available, which exist in commerce, as a direct and essential consequence of nuclear power." In order to get plutonium for weapons, one needs a reactor, whether it is a "research" reactor (such as the one which provided India with the fissile material for its first atomic bomb). or a commercial reactor.
Neutrons from the fission of uranium-235 are captured by uranium-238 nuclei to form uranium-239; a beta decay converts a neutron into a proton to form Np-239 (half-life 2.36 days) and another beta decay forms plutonium-239.
All plutonium originates in nuclear reactors and is produced by the capture of extra neutrons by uranium-238 to form U-239, which then undergoes a series of decays to form Pu-239: U-238 + n -> U-239 -> Np-239 -> Pu-239. Some of this plutonium gets consumed by fission before it is removed from the reactor, and some of it gets transmuted to heavier isotopes of plutonium by capturing more neutrons: Pu-239 + n -> Pu-240
Quote from: clongton on 04/27/2017 04:45 pmIn the early days of the start of the nuclear age there were many types of fuel and reactor designs being considered and tested. Most were flops. In the end it came down to a choice between two fuels; Thorium and Uranium. Both fuels have impressive lists of advantages and disadvantages. Both fuels ran reactors for hundreds of thousands of hours with no problems. In the end it came down to uranium having a single insurmountable advantage over thorium. One needs to consider the context of the times to really understand this but it was a really, really big deal to the United States at the time. The real reason we use uranium over thorium is a result of wartime politics. Cold War-era governments (including ours) backed uranium-based reactors because they produced weapons-grade plutonium —for atomic bombs and icbm warheads. Thorium powered reactors could only produce electricity – no bombs. Every other issue mentioned here is an unimportant aside detail.False. The plutonium produced in power plants is unsuitable for use in nuclear weapons.
Quote from: ChrisWilson68 on 04/28/2017 07:34 amQuote from: clongton on 04/27/2017 04:45 pmIn the early days of the start of the nuclear age there were many types of fuel and reactor designs being considered and tested. Most were flops. In the end it came down to a choice between two fuels; Thorium and Uranium. Both fuels have impressive lists of advantages and disadvantages. Both fuels ran reactors for hundreds of thousands of hours with no problems. In the end it came down to uranium having a single insurmountable advantage over thorium. One needs to consider the context of the times to really understand this but it was a really, really big deal to the United States at the time. The real reason we use uranium over thorium is a result of wartime politics. Cold War-era governments (including ours) backed uranium-based reactors because they produced weapons-grade plutonium —for atomic bombs and icbm warheads. Thorium powered reactors could only produce electricity – no bombs. Every other issue mentioned here is an unimportant aside detail.False. The plutonium produced in power plants is unsuitable for use in nuclear weapons.Well... if you operate them "normally", yes, the resulting plutonium will be no good for bombs (contaminated by Pu240,241,242). However, if you run power reactor for a short time (a month or even less) and then unload and process the fuel, then you get weapon-grade Pu.Ironically, that's what effectively happened at Three Mile Island. The accident happened early in the very first fuel campaign of Unit 2, and therefore fuel debris from the TMI accident contained weapon-grade plutonium. After reactor vessel cleanup, It was decided to hand it over for storage to the military.
Plutonium does not exist naturally to be mined. It is only available as a byproduct of a nuclear fuel cycle that uses uranium as the fuel. There is no nuclear fuel cycle of any kind with thorium that can produce plutonium and THAT is why uranium was chosen as the fuel for nuclear reactors.
Quote from: clongton on 05/03/2017 11:41 pmPlutonium does not exist naturally to be mined. It is only available as a byproduct of a nuclear fuel cycle that uses uranium as the fuel. There is no nuclear fuel cycle of any kind with thorium that can produce plutonium and THAT is why uranium was chosen as the fuel for nuclear reactors.I already refuted that in the post you replied to, but you offered nothing that addressed the refutation.
Quote from: gospacex on 05/04/2017 12:00 amQuote from: ChrisWilson68 on 04/28/2017 07:34 amQuote from: clongton on 04/27/2017 04:45 pmIn the early days of the start of the nuclear age there were many types of fuel and reactor designs being considered and tested. Most were flops. In the end it came down to a choice between two fuels; Thorium and Uranium. Both fuels have impressive lists of advantages and disadvantages. Both fuels ran reactors for hundreds of thousands of hours with no problems. In the end it came down to uranium having a single insurmountable advantage over thorium. One needs to consider the context of the times to really understand this but it was a really, really big deal to the United States at the time. The real reason we use uranium over thorium is a result of wartime politics. Cold War-era governments (including ours) backed uranium-based reactors because they produced weapons-grade plutonium —for atomic bombs and icbm warheads. Thorium powered reactors could only produce electricity – no bombs. Every other issue mentioned here is an unimportant aside detail.False. The plutonium produced in power plants is unsuitable for use in nuclear weapons.Well... if you operate them "normally", yes, the resulting plutonium will be no good for bombs (contaminated by Pu240,241,242). However, if you run power reactor for a short time (a month or even less) and then unload and process the fuel, then you get weapon-grade Pu.Ironically, that's what effectively happened at Three Mile Island. The accident happened early in the very first fuel campaign of Unit 2, and therefore fuel debris from the TMI accident contained weapon-grade plutonium. After reactor vessel cleanup, It was decided to hand it over for storage to the military.In both the West and the Soviet block, all plutonium ever used in nuclear weapons came from special reactors designed and built explicitly to produce weapons-grade plutonium. None of it ever came from a power reactor -- not even the power reactors designed and owned by the military, such as those in aircraft carriers and submarines.So the claim that uranium was chosen over thorium for power reactors because it generated plutonium for nuclear weapons is false.
There are three primary isotopes that can be used as fissile materials (materials than can support a nuclear chain reaction).