A whole lot of fissioning going on – Nuclear Power by Amelia Frahm

16 Comments

1. For those who want to see a brainy and entertaining presentation on nuclear energy, there is this great and passionate bit from Steven Cowley.

   Some say that he will get fusion working. He is a top scientist and listen to him give a great explanation of what differentiates fusion from fission at 3:28 from the video here :

   http://www.ted.com/talks/lang/eng/steven_cowley_fusion_is_energy_s_future.html

   But I really think that education to kids and growing minds is the key to nuclear adoption in the long run.

2. @Daniel – thank you for the link.

   That is another excellent example of why I really dislike and disrespect the physicists who lie through their teeth about the limitations of fission. Cowley’s talk includes a graph with a huge underestimate of uranium resources and a complete blackout with regard to thorium resources.

   I presume that the numbers were selected in order to attempt to capture more money so he and his theoretical physicist buddies can build large toys – in the south of France. Cowley admits to being one of the few people who is happy when Putin turns off the gas taps because it makes his budget grow. He alsi admits that the south of France is a rather pleasant place to do fusion research.

   He vastly underestimates the cost of the yet to be imagined and invented machinery that will be required to turn fusion heat energy released at 150 million degrees (he did not mention which scale) into useful electrical energy.

   Finally, he overlooks the fact that his device will depend on perfectly capturing every neutron released if viewed in isolation from other potential neutron sources – like fission.

   Think about it. Every D-T fusion requires a T, which is not found in nature. He proposes that it can be manufactured by a neutron reaction with Li-6, which is also not found in nature in a pure state.

   Every D-T fusion reaction only produces one neutron, so in order to feed a D-T fusion device with a continuing supply of tritium without the help of fission reactors, every single neutron must be used to hit Li-6 to create one tritium.

   One more thing – though deuterium is naturally occurring, its concentration in water is only one part in every 8,000 hydrogen atoms.

   With all due respect to an eminent physicist – I will quote Penn and Teller. “That’s BS.”

   1. I find him entertaining and I learned watching him. I had also picked up the low Uranium reserves and also the problems linked to the containment walls that go unadressed. I guess we all run into conflicts of interest when we are too deep into a cause.

   2. So if fusion 30 years away and always will be?

      1. Is fusion 30 years away and always will be?

         1. Something like that.

            The scam I like best is He3 mines on the Moon for fusion fuel! I guess if your going to dream, dream in Techincolor.

   3. For 150 million degrees, I would say it is almost irrelevant what temperature scale is used.

      1. 150 Million Degrees C is 270 Million Degrees F, scale is never irrelevant.

         1. I meant in terms of concern about material compatibility and such.

            150 million F (aka 150,000,460 Rankine) would instantly destroy essentially anything just the same as 150 million C (aka 150,000,273.15 Kelvin).

   4. Adams says,

      “Think about it. Every D-T fusion requires a T, which is not found in nature. He proposes that it can be manufactured by a neutron reaction with Li-6, which is also not found in nature in a pure state.

      Every D-T fusion reaction only produces one neutron, so in order to feed a D-T fusion device with a continuing supply of tritium without the help of fission reactors, every single neutron must be used to hit Li-6 to create one tritium.

      — emphasis mine.

      Rod’s error was also committed by the builders of the fusion bomb that was tested in the Castle Bravo test. As Wikipedia’s Castle Bravo article today says,

      The yield of 15 megatons was two and a half times what was expected. The cause of the high yield was a theoretical error made by designers of the device at Los Alamos National Laboratory. They considered only the lithium-6 isotope in the lithium deuteride secondary to be reactive; the lithium-7 isotope, accounting for 60% of the lithium content,[citation needed] was assumed to be inert.
      It was expected that lithium-6 isotope would absorb a neutron from the fissioning plutonium and emit an alpha particle and tritium in the process, of which the latter would then fuse with the deuterium and increase the yield in a predicted manner. Lithium-6 obeyed this assumption.
      However, when a lithium-7 isotope is bombarded with energetic neutrons, it captures a neutron then decomposes to form an alpha particle, a tritium nucleus, and the captured neutron. This means more tritium was produced than expected, and the extra tritium is fused with deuterium. In addition to tritium formation the extra neutron released from lithium-7 decomposition produced a larger neutron flux.

      In their defense, they were working in about 1953.

      1. I could very well be wrong, but GRL’s explanation still does not seem to provide any additional source of neutrons from fusion. One neutron still produces just one tritium, and the production of each tritium requires a neutron, which does not allow for any absorptiom in other materials or leakage out of the system.

         In the bomb situation, there was a rich source of neutrons from the initiating fission device.

         1. Rod, as others pointed out, the Li7 reaction allows for some neutron losses, the reaction is:

            Li7 + n —> H3 + He4 + n

            So, while you don’t get additional neutrons like in fission, you get to “recycle” neutrons (i.e. the neutron is active as a sort of catalyst). The result is that you get more than one H3 out of a single neutron, which can potentially make up for neutron losses.

            On the other hand, the tokamak fusion reactors are quite the engineering nightmares. A fission reactor is (simplified) a “pot of water/salt/sodium/some other liquid” and the complicated machinery is dedicated to getting the heat out, in a tokamak lots of complicated machinery is dedicated just to get things going: Huge, superconducting magnets, neutron beam heaters, etc. and this is before you even start getting the heat to turbines to make useful power.

            In addition, there are a bunch of things that are just engineering nightmares, even if you can get the reaction going: You need a huge cryostat that cools the magnets which are “conveniently” located right next to the (very hot) breeding blanket and the neutron flux is just terrible: You get a huge amount of extremely energetic neutrons which tend to smash all the materials between the reactor wall and the blanket to bits.

            I think the problem with the tokamak isn’t the tritium breeding, it’s the sheer complexity of the machine, which makes it doubtful whether one can turn it into a practical (and affordable) power plant, even if it works. I may be wrong, in fact, I hope I’m wrong but the evidence doesn’t look good.

   5. Cowley’s talk includes a graph with a huge underestimate of uranium resources and a complete blackout with regard to thorium resources.

      If FBRs are considered, the USA already has U-238 equivalent to about 300 years of total energy consumption, already mined, refined and sitting in warehouses as UF4 and UF6.

3. I could very well be wrong, but GRL’s explanation still does not seem to provide any additional source of neutrons from fusion…/blockquote>

   True …

   One neutron still produces just one tritium.

   False. A fast neutron — even just a fission neutron, but especially a 14.1-MeV DT fusion one — that is captured by a 7-Li nucleus gives an excited lithium-8 nucleus that can shed a triton. If it does, there remains a helium-five nucleus.

   That means you get your neutron back, and if it had 14.1 MeV to start with, I guess it still has the good MeVs. It could do more lithium-7s before finally being used up by a lithium-6.

4. .. as others pointed out, the Li7 reaction allows for some neutron losses …

   I all appreciate the notice.

5. Rod,
   Thanks so much for posting this clip and mentioning my book.

   Mom’s Choice Awards has notified me that “Nuclear Power: How a Nuclear Power Plant Really Works!” has been named among the best in family-friendly media, products and services in science & technology and children’s picture book categories. Woo Hoo!

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