1. It’s great to hear that GE-H is finally moving forward with plans to get a prototype PRISM facility built. Rod, I hope B&W and their mPower succeed and make your employer and you a good amount of money, but I also hope that the PRISM succeeds wildly in the coming decades, because I really see PRISM as being a GREAT THING – because in addition to providing power like other nuclear reactors, they also represent what seems like the only hope for dealing with long-lived nuclear waste – burning it up into short-lived waste.
    I’m thinking I may try to invest in GE (or Hitachi? right now, I’m confused who to invest in to support and benefit from the PRISM) at some point, because I really think the PRISM, if the prototype works out, could really be a big seller.

    1. The concern I have with the IFR/PRISM and all other proposed reactors that use sodium metal as a coolant is that it appears to me that most historical reactors that have used sodium metal as a coolant have tended to achieve underwhelming success, especially when scaled to medium to large sizes (e.g. 100-200 MWth+ or larger).
      Sodium metal, from what I understand as a non-engineer, makes the core completely inaccessible without remote handling equipment, due to its physical characteristics – you can’t see through liquid metal or make adjustments to things immersed within it, at least not easily. Plus, when activated by neutrons, gamma production from sodium is high, and if sodium metal is exposed to air or water, vigorous chemical reactions occur.
      Why can’t the IFR/PRISM use some coolant like lead, lead-bismuth eutectic or something other than sodium? And, if the people who are building the IFR/PRISM are determined to use sodium, have they developed a detailed plan based on past lessons learned from previous sodium reactors to avoid negative outcomes?
      (The Russian experience with the successful BN series of sodium-cooled reactors may provide a counterexample to the Western experience with sodium, but this seems to be based exclusively on Russian technology that the West has no access to.)

      1. @Dave: Well, I too am a bit concerned about sodium – one of the criticisms I’ve heard of Chernobyl, and why it became as bad as it did, is that the moderator (graphite), burned during the reactor failure. Of course, Chernobyl had other problems as well, that wasn’t the only factor. However, I wonder if, should something bad ever happen with a PRISM, if the Sodium could burn and greatly aggrevate the problem?
        Well, I suppose the GE-H engineers who’ve been looking at this problem for 20 years or whatever have some reason they feel sodium is the best coolant (I don’t think the Sodium will be ‘moderating’ the reactor though, since it is a fast reactor design). Still, once they get a prototype plant built at that Savanah River site, they can start to get more familiarity with operation characteristics, to see if they’ll have the type of problems you suggest may come with Sodium cooling.
        That’s the thing – I’m not suggesting we drop everything and build 100 PRISMs in the next 10 years, but let’s get one or two built, and start testing them and pushing them a bit to see what problems might develop.

      2. @Dave
        Many experimental breeder reactors have been technical successes but commercial failures because they are a good solution to a problem we don’t have; not enough uranium.

      3. Sodium isn’t so bad. The first electricity ever produced by nuclear power was generated by a reactor that was cooled by a sodium alloy. It’s successor, which was cooled by sodium, ran for 25 years — not bad for an experimental reactor.
        Almost all of the problems with sodium-cooled reactors have been political, not technical, the main problem being programs being shut down due to political considerations, just when the initial technical “problems” are being ironed out.

        1. @Brian – agreed. Sodium is no more “inherently dangerous” than is water that is at 640 F and really, really wants to become steam. Both require careful attention to detail in engineering, manufacturing and operation, but both can be safely employed as working heat transfer fluids.
          Some of the political problems associated with sodium have come from within the nuclear industry – not only do people who specialize in hot water and thermal reactivity feel a bit threatened (from a career point of view) by the idea of using sodium, but the good folks in the uranium mining and nuclear fuel supply chain also recognize that some of their capital investments might be made obsolete if we use fast reactors using metal fuels with plutonium recycle.
          The “energy is a scarce commodity” crowd is also quite threatened – using sodium cooled fast reactors completely disrupts that carefully sold presumption.

  2. The main reason why power reactors have “only come in one size – extra-large” for a period of time is fairly easily found. It’s the regulatory burden, which is to a large extent based on reactor count. So once the decision is made to take on that burden, the way to maximize the positive return is to maximize the size of the reactor.
    If I am correct about this, it means that small reactors could easily make big contributions quickly once the regulations are corrected to focus burden on risk / complexity level rather than reactor count.

      1. Of course not! They’re not large problems, they’re large business opportunities!
        Gore thinks that he can make boatloads of money by selling worthless “solutions” to Climate Change (or whatever it’s called these days), and when none of these solutions work, he can make additional boatloads by selling worthless carbon offsets.
        A modest amount of new nuclear plants won’t upset this business model. A large number of new nuclear plants would devastate it.

    1. Why does not the economy of scale rule, which is widely observed to operate in other industrial process environments like the petrochemical industry, not work in the nuclear industry as regards building large nuclear reactors?
      What are the real cost drivers for nuclear power plants and why do these costs not scale with size?

      1. Robert – the “economy of scale” is widely misunderstood by many engineers. It does not have to be achieved by building ever larger units. Often, it can be achieved by putting a number of identical units in parallel in the same facility.
        The economy of series production that affects all other manufacturing industries applies to nuclear energy plant components.
        The big cost driver for nuclear is the plant capital cost – it dominates the equations in my cost per unit of output spreadsheets for the first 15-25 years until the notes are paid off. Seeking ever larger initial sizes demands ever larger and more unique components that each cost far more than a smaller component made in a larger volume manufacturing process.
        Engineering and licensing costs also drop on a per unit basis if you do the job correctly and make few changes as time goes on. Of course, that does not always make the design engineers happy – they LIKE to change things.

  3. @Brian — According to John Holdren, it’s known as “Global Climate Disruption”. Covers all contingencies, you see?

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