Three Years Ago at Google

43 years ago today, man first walked on the Moon.

Three years ago today, I went to Google for the first time and gave a talk there. It was a formative event in more than one way. I met Chris Uhlik, who now serves on the Board of Advisors for Flibe Energy. Chris was one of the people, who, in years to come, was a powerful influence on my thinking and was part of the reason we started Flibe Energy. I met Iain McClatchie in person, and Iain has been another voice of advice and guidance as we have attempted to move the development of LFTR forward. And I got to meet “Google”…seeing the campus and the people, how and where they worked, it also had a lot to do with shaping my thoughts for how a high-technology company could and should be.

I didn’t know how things would ultimately turn out that day at Google, and I’m sure I would have been surprised. But I’m certainly glad that I made that trip to California and gave that talk.

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13 Replies to "Three Years Ago at Google"

  • jstults
    July 20, 2012 (11:52 am)
    Reply

    Why is the nuclear aircraft a "fools errand"? The Flibe site claims you can scale down to 1-2MW; that's small turboprop territory…

  • G.R.L. Cowan
    July 20, 2012 (3:15 pm)
    Reply

    Below ~200 thermal megawatts (the power typical of today's nuclear ships), you can scale the power down by any amount you like, but the mass reaches an irreducible minimum. This minimum is the weight of an omnidirectional neutron and gamma ray shield, and is on the order of 100 tonnes.

    For an aircraft, you might want *two* omnidirectional neutron and gamma shields, with one reactor inside each, in case you have to shut one down.

  • Jagdish
    July 20, 2012 (11:36 pm)
    Reply

    For aircraft and missiles, power to mass ratio is critical and there is nothing to beat hydrocarbons for the purpose.
    Thorium cannot burn without fissile feed, which is U-235 or derivatives Pu239 or U-233. On the pro side, thorium produces more fissile during its burning and burns longer than uranium before being overwhelmed by fission product poisons.
    My layman reasoning tells me that the best solution would be using a fast reactor 'Wick' of U-238/Pu-239 to burn a surrounding thorium 'Wax' in a thermalised spectrum

  • jstults
    July 21, 2012 (10:44 am)
    Reply

    G.R.L. Cowan, thanks for your informative reply.

    I read up a bit more on the old nuclear aircraft program. I think you are right that shielding is the killer, looks like you were just off by an order of magnitude or so on the mass: looks like they were using 12 tons of shielding.

  • IceTrey
    July 21, 2012 (5:57 pm)
    Reply

    Thorium doesn't burn in a LFTR, it's just bred to uranium which is then burned.

  • Peter
    July 24, 2012 (6:16 am)
    Reply

    Ice trey, "just" breeding thorium to uranium! That statement is literally equivalent to "just" turning stone to gold.

  • KAP
    July 24, 2012 (11:59 am)
    Reply

    Power-to-weight ratio is important for aircraft, but not as much as most people believe. A flying wing, for example, has a wing area so large that it can lift huge loads. The penalty you pay is speed, because a large wing also has lots of drag.

    So the concept of a nuclear aircraft might actually be practical for some applications, where you don't need high speed but you do need extreme endurance. A nuclear-powered observation platform with multi-year flight endurance would be an interesting concept, and would have some distinct advantages over satellites: it could loiter over a desired area, it would be closer to the ground and therefore capable of delivering higher-resolution images, it could be landed for repair and re-deployed at any time. And the cost could be comparable.

  • ROBERTM
    July 25, 2012 (3:56 am)
    Reply

    I just want a small thorium desalination/electricity plant for use in areas where fresh water is not available.

  • G.R.L. Cowan, hydrog
    July 25, 2012 (10:28 am)
    Reply

    I think you are right that shielding is the killer, looks like you were just off by an order of magnitude or so on the mass: looks like they were using 12 tons of shielding.

    If I recall correctly, that shielded only the cockpit.

    Actually the minimum mass, for that sort of arrangement, would be a half-shield around the reactor and a half-shield around the cockpit. So the crew would be adequately shielded, but on the ground, maintenance would have to be by rad-hardy robots.

  • Chris Uhlik
    July 26, 2012 (12:41 am)
    Reply

    For nuclear powered aircraft, I recommend synthesizing jet fuel from biomass/garbage by combining with LFTR heat and hydrogen from more LFTR heat. This method is indirect, but relatively easy to deploy compared to putting nuclear reactors in the actual airplanes.

  • Rick Armknecht
    July 27, 2012 (5:42 pm)
    Reply

    Another thing that could reduce the amount of shielding required for a nuclear-powered aircraft: the length of the aircraft. If the power plant is located at the extreme rear of the plane, and the crew is all in a cockpit located at the extreme front of the plane, then the shielding could be reduced the longer the plane is because the radiation flux decreases as a function of the square of the distance from the radiation source.

  • Peter
    July 30, 2012 (8:53 pm)
    Reply

    Rick, how about a glider pulled by a remotely operated nuclear tow plane. You could obtain a fairly long distance.

  • G.R.L. Cowan, hydrog
    August 1, 2012 (2:51 pm)
    Reply

    Peter says:

    … how about a glider pulled by a remotely operated nuclear tow plane.

    They did of course look at that arrangement, back in the day, and now, I can tell you, they're actually testing it in reserved military airspace near you. Weren't you informed? Everyone else was.

    If the unmanned tractor part gets too screwed up, they'll just cut it loose, and land the manned trailer using a small kerosene-burning backup motor.

    Back, but not quite in the day.


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