Wednesday, May 23, 2012

New Nuclear Technology and Nuclear Proliferation.

During World War II the United States spent a large amount of money on developing nuclear technology. Much of that investment went into industrial systems designed to separate U-235 from U-238, or to transform U-238 into Pu-239. Here such systems were built in Oak Ridge, Tennessee, My childhood hometown. The Uranium separation technologies were gaseous diffusion, thermal diffusion and electromagnetic separation. In addition, Plutonium was produced in the Graphite Reactor. Of the 4 technologies, thermal diffusion was the least successful.

The almost unknown Oak Ridge thermal diffusion plant, S-50, was capable of tripling natural uranium's enrichment, but that level of enrichment was not very useful. During WW II thermal diffusion processed uranium was used to speed up the output of K-25, the gaseous diffusion plant. As soon as World War II was over, the S-50 plant was shut down, The electromagnetic plant was hugely expensive to build and operate, and not nearly as effective as gaseous diffusion separation. Electro magnetic was accomplished by means of a device called the calutron. Oak Ridge Y-12 calutrons were expensive to build, because of the amount of silver that went into them. They were also expensive to operate, because their operation required a large amount of electricity. By 1946 all but one of the Y-12 Calutrons were shutdown. However, the calutron was considered sufficiently successful to under development as a proliferation tool by Iraq prior to the First Gulf War.

Gaseous diffusion was a successful but expensive to develop and operate technology Gaseous diffusion production was developed by the United States, the Soviet Union, China, the United Kingdom and France. The major drawback to gaseous diffusion is the expense of operation. The technology requires a lot of electricity. For this reason gaseous diffusion plants are being shut down and replaced by centrifuges.

The Oak Ridge X-10 Graphite reactor was never intended to produce plutonium for weapons, instead the reactor was intended to support research, that would contribute to the development of the Handford weapons complex.However, given enough time the X-10 Graphite reactor could have produced enough weapons grade Pu-239 to build one or more nuclear weapons. In fact the United Kingdom's first two military grade Pu-239 facilitated designs that were closely related to that of the graphite reactors. The design of later Pu-239 production reactors used graphite cores. Finally the design of the reactor which North Korea uses to produce its nuclear devices is closely related to the UK's Second Generation weapons productions Reactors. The Handford Reactors were water cool graphite piles, a design that was also adopted by the Soviet Union.

I should mention two more Uranium separation technologies. The first is is the centrifuge. Ye centrifuge uses far less electricity than the Gaseous diffusion method, but is relatively simple to build. Even Nations that are nor highly advanced industrially, are capable of producing Centrifuges, and centrifuge arrays, capable of producing weapons.grade U-235. Pakistan's nuclear weapons program is based on centrifuge technology, even though Pakistan is not advanced industrial state.

I should mention one more successful Uranium separation, the Aerodynamic separation process. This system is in expensive to build, and has been successfully used by South Africa to produce the U235 needed to manufacture 6 nuclear weapons. The major drawback of Aerodynamic separation is that it requires a lot of electricity. Yet if a small country wishes to produce a few nuclear weapons at a relatively low cost, Aerodynamic separation is the way to go. On the other hand, Aerodynamics separation is not as low cost as centrifuge separation for a bigger5 nuclear program.

Finally, we come to heavy water reactors, a class of reactors that uses water with one atom of deuterium rather than simple hydrogen. Heavy water is a superior moderator, better even than graphite. and thus heavy water reactors are excellent producers of Pu-239. Three nations have used Heavy water reactors, to produce weapons grade plutonium for nuclear weapons. they are the United States, India and Israel. The American reactors were large and complex reactors deployed as part of an industrial system designed to produce Hydrogen Bombs. Both the Indian and the Israeli reactors were the result the heavy water reactor project carried out by British, French and Canadian scientists during World War II. After the war, France assisted Israels program to develop nuclear weapons. The modified copy of the WW II jointly developed reactor was passed by the French to the Israelis/ The Indian reactor was quite similar and was sold to India by Canada.

Thus any nation would have a wide variety of tested options available to it, If it wished to produce locally made weapons grade materials. The cost of producing a limited amount of such material is not great, and there are tested production methods.

Rational decisions and decision makers and nuclear proliferation

Decision makers who are on the whole rational are much more likely make decisions that lead to successful nuclear weapons programs. On the whole small programs are more likely to be successful than large programs. Lower cost nuclear materials are more desirable than higher cost materials, that have no more military usefulness. Programs using proven technology are more likely to sauced than programs that use unproven technology. Programs using simple technology are more likely to succeed than programs using complex technology.

The first explosion of a nuclear weapon was a test of a Pu-239 weapon. The first test of a U-235 weapon was occurred when it was used against the Japanese. the triggering mechanism of the U-235 bomb was very simple, while the triggering of the Plutonium bombs triggering was far more complex. Of course if you have got help. you may not need a test. Israel has, as far as we know, never tested a nuclear weapon, yet its weapons appears to use Pu-239. leads to easier for bomb design to vaporize than U-235. Thus U-235 is the weapons material of choice for nations with limited weapons technology skills.

There are well defined and tested paths to nuclear proliferation, most of which use World War II ans Cold War era technology. In contrast new nuclear technology, for example the LFTR, does not provide a tested path to weapons production. Given potential costs, and other uncertainties which new nuclear technology poses to nations seeking to acquire nuclear weapons, More traditional routes would be far more appealing.

Thus the LFTR and other generation IV reactors do not make nuclear proliferation more likely, and they are not particularly useful proliferation tools. It should be noted that while the United States government regards Laser isotope separation to pose a serious proliferation. it does not regard Molten Salt Reactor technology to pose proliferation dangers.
Not all paths to nuclear weapon development technologies are created equal. Some are simpler, lower cost, and better tested than others. Would be proliferators are most likely to choose the simplest, best tested and lowest cost path available to them. The development of new, more expensive, and more challenging paths to the spread of nuclear weapons is very unlikely to increase the spread of nuclear weapons. This warning about the proliferation dangers of new nuclear technologies, may represent bogus expressions of an anti-nuclear stance. It is not enough to claim that a new nuclear technology poses s proliferation danger. The proliferation argument must show how the development of new nuclear technology increases the likelihood that the new technology will lead to nuclear proliferation.


jimwg said...

I'm as anti-nuclear war as the next man, but then I've seen how the understandable flurry to abolish nuclear bombs (explosives) have denied us, via international bans, of using nuclear explosives for mining and light terraforming and for deep space applications. The irony is that one of the most popular peace-niks around, Carl Sagan, was very much for using nuclear explosions to drive the Orion spacecraft concept, which could literally push spacecraft with the mass of WWI destroyers around the solar system within mere months, and even be applied interstellar -- and this could've been done with the technology of the 1970's weren't for the U.N.'s space nuclear test ban treaty's throwing the baby out with the bathwater, which is overdue to be rewritten if we're to make serious progress in the solar system.

James Greenidge
Queens NY

Unknown said...

Haven't the USA created a U-233 bomb??.
Also, if you speak to the certain weapons experts that I won't name they will tell you that a lower mass of U-233 is required to bomb than Pu or U-235.

So for a sophisticated state (one with an advanced nuclear infrastructure) the time from the beginning of a "break out" scenario to produce/divert a significant quantity of material is quick (depending on the existance of dedicated failities, time taken to process materials and time needed to modify any civil facilities that are used).

The only thing that stands in the way normally is U-232 which makes U-233 hard to handle due to it being an intense gamma emitter (this is not an issue for a sophisticated state).. And U-232 as an impurity that absorbs neutrons... This can influence diversion time as it will take time to alter facilities and produce material lower in U-232.. Alternatively (if U-232 content is below a certain levell which heavily afects poisoning) a sophisticated state with a critical mass of material could turn it into a bomb (ask any weapons expert)..

So while there are advantages to U-Th cycle in terms of proliferation.. The same issues are still there. And if a sophisticated state is determined and has the resources and funds at hand, it will be able to overtly use civil facilites to produce a weapon!

Charles Barton said...

Gillis, the only test of a nuclear device which contained U-233 was some what less than a success. That test involved the use of U=344 that was especially produced to be weaponizable, just as Pu-239 is produced to be weaponizable.

Secondly, even if there were no U-232 related storage and handling probems, U-233 weapons still require testing before they they are used, because the one test of U-233 raises questions about its yield. U-232 does not make weaponization impossible, but it makes weapons handeling and storage more difficult.

Finally, the diversion of U-233 from a DMSR is impossible without also diverting 80% U-238. For LFTRs, there are several obsticles to diversion. One is the fact that any U-233 extracted from the reactor could be kept in a hot cell untill use. By hot I mean both physically hot as well as radioactive. Diversion is a problem only if there is no accountability for fissionable naterials, and those materials are physically accessable to the would be diverters. Most states which possess nuclear weapons, are careful, to make sure that their weapons grade fissionable materials are not easily accessible by would be diverters.

NNadir said...

In general, U-233 can be used to effectively "denature" natural uranium when it is used with uranium from used nuclear fuel.

Under these circumstances, uranium will contain U-232, U-233, U-234, U-235, U-236 and U-238. (U-237 is not long lived enough to participate.

Note that U-234 would be enriched in this case, owing to the neutron capture in Pa-233 (27 d half-life) during preparation, as well in U-233 itself.

This effectively destroys the effectiveness of gaseous diffusion and centrifuge approaches (which would also enrich U-232 to the maximum extent) as well as (to a lesser extent) laser based approaches.

Natural uranium can always be enriched, and thus the only "zero option" for proliferation would be to fission all of the uranium that exists, something I assure you will never happen.

Anonymous said...

Worries about nuclear technology and nuclear proliferation seem, to me, to focus on the wrong issues.

Any state with access to WWII-era technology can, without much difficulty, create a tried-and-tested nuclear weapon. Giing them extra and untested options doesn't alter this fact, and it's pretty dubious to assert it would make proliferation more likely - arguably, better international cooperation and strengthening of inspection regimes under the Non-Proliferation Treaty are needed, but wouldn't become less effective by having different kinds of civilian reactors in operation.

There's even a question of how far nuclear proliferation matters at the level of a sophisticated nation - Germany does not have nuclear weapons, but it has a large enough and advanced enough air force that it could wipe out cities with conventional bombs if it chose, so the increase in the potential for mass destruction is surprisingly marginal. For weaker states like North Korea that lack the capacity to project military force this way, the Bomb is a bigger risk, but they're also far less likely to have the independent expertise needed to create a novel form of nuclear weapon, especially if it would have to use a more expensive, less reliable, and generally inferior path to doing so - and it remains true that nuclear deterrance has proven effective in the past, if a tad unstable.

Set against the prospect of a new kind of nuclear weapon using U-233, one has to consider that the adoption of a thorium fuel cycle would remove any excuse for using proliferation-prone gas diffusion or plutonium-breeding reactors, limiting the ability of states to try and cover a weapons program with a civilian one. If Iran were offered a functioning LFTR for which they'd not need their diffusion plants, and they refused, it's be a pretty obvious statement that they were pursuing a weapon, not a reactor.

That aside, the big proliferation risk with any nuclear technology, to my mind, is that non-state actors gain easy access to weapons-grade material. Terrorists of course are the biggest threat, with lesser threats from corporations, NGOs, organised criminal networks, etc. This is the nightmare scenario since such weapons genuinely do add a completely new capacity to such groups - terrorists, thankfully, are not capable of wiping out large cities in pursuit of their ideology. This situation is arguably easier to prevent arising, though, by designing reactors such that fissile material is at no point free and weapon-ready - contamination of U-233 with U-232 for instance renders it extremely hard to use without further processing; if it's never kept separate from the protactinium and its decay products, and kept in circulation within the reactor while U-233 is bred, there's no way a feasible terrorist group could steal it without a major (and obvious) capture of the whole plant for days or weeks. Plutonium breeder reactors might be even safer, since plutonium is actually fairly difficult to weaponise, compared to uranium-235.

All these issues need to be considered before deployment, certainly, but at the cost of a little efficiency, plants can be made remarkably proliferation-proof.

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