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  1. Here’s something I just posted over on RealClimate:

    We have nuclear technologies which can double our inventory of certain fissiles in roughly 10.5 months*.  Figure 1 year to account for handling delays.  Figuring 54 tons of surplus weapons plutonium as the starting supply (what the USA has in decommissioned weapons “pits”), fissile inventory of 100 kg per GW(e), consumption of 1 ton per year per GW(e) and breeding ratio of 1.08†, we could start 540 GW(e) of reactors with what we have on hand and double this every year.  This effort would be kick-started by plutonium but very quickly run on the Th-U-233 fuel cycle.  World electric consumption in 2013 was 19,504 TWh or about 2.2 TW average; two doublings would get us to world 2013 levels of electric generation, and another two doublings would encompass all world energy consumption and then some.  That’s 4 years.

    These are the sorts of things we built in a jiffy during actual wartime.  Why is this not being treated the same?

    * This would require a thorium-uranium cycle with protactinium extraction.  Might require a 2-fluid design.

    † Figures for a thermal-spectrum thorium breeder from memory, could be unreliable.

  2. Well, one good thing: Oklo will be showing their hand with this COLA. Do they have 5 of one suit?

    They’ve been very cagy for ‘apple type vibe’ reasons. Looking forward to elucidation why anybody thinks there will be utility in a 3MW fast reactor.

    1. Michael Scarangella — Military applications. More generally off-grid applications such as in the far north communities and mines. Currently such areas consume expen$ive diesel fuel.

        1. @Michael scarangella

          Do you have any cost estimates for Triso fuel? What is the basis for your implication that those who are interested in its use believe “cost is no object?”

          IMO, Triso is well suited for tracking down a steep manufacturing cost reduction curve. The shape is simple and the coatings are made of low cost elements. At the low volume needed for experiments and testing, it’s an expensive product. But that statement is true of any product produced at experimental volumes.

          Heck, it was even true in the plastic product manufacturing business I managed.

    2. There is great value in this depending on the overall cost. I have lived on Islands where the cost of providing power is enormous. If the cost per unit is reasonable these could also be grouped into a greater output. There are many communities who had 11 or 15 MW coal plants to power their towns. These have been overtaken by the massive power plants currently running. Having the option of powering your city with a set of 10 of these would be attractive to towns of 30,000 people.

      1. An island of 30,000 people should have 2×100 MWe LWRs and an 80MW Wärtsilä-Sulzer RTA96-C bunker oil burning back-up. A mainland town of 30,000 people should have a switch-yard. Puerto Rico should have 3xABWRs @1.3GWe/ea operated at 65% licensed power and forget where the electricity comes from for 80 years.

        When the details of the micro reactor fuel cycle become available, it will be rather simple to back-out the fuel cost per MWe-hr. There are online feed/swu/conversion tools that give reasonable answers (just be careful using spot prices):


        Neutrons travel about 3cm in H2O prior to absorption; they travel ~60cm in graphite per textbook. Neutrons travel farther when they are slowed less effectively. In small fast reactors, many neutrons escape the reaction zone; enrichment is increased to compensate for leakage. It is never better to have many smaller reactors; it is always better to have fewer larger reactors. Fuel economy is at the limit of worst possible for micro reactors. In a large LWR, fuel costs are about $8/MWe-hr; fuel costs in a micro reactor could be two orders of magnitude greater. It’s really irrelevant when you consider that the 1.5MWe reactor needs an operator, or at least an attendant, and that this person will likely make $100/hr. Surely, someone will make the counter-argument about using micro-reactors at the bleeding edge of the habitable zone. I simply ask: Who lives there?

        1. @Michael Scarengella

          Nuclear power systems producing small quantities of output power and heat do not necessarily have tiny reactor cores.

          Far too much focus has been placed on core size and efficiency while ignoring system size and complexity. One of my inspirations is looking at nuclear power plant wall charts. Those fascinating pieces of engineering/architectural art show how most cores are so small they are almost invisible in a drawing intended to illustrate an entire plant.

          A core the size of HTR-10 is large enough to minimize effects of leakage, but combine that with a direct cycle nitrogen Brayton cycle gas turbine and you have a rather compact 2-4 MWe generator that also produces 3-5 MWth of potentially useful heat. (Those numbers don’t add up to the 10 MWth input. Even cogeneration cycles have some amount of useless heat that qualifies as waste.)

  3. “That natural market behavior gets confusing to outside observers when the suppliers that choose to exit seem to be some of the cleanest, highest quality, lowest cost sources in the market. ”

    Many other sources of power that rely on combustion produce the economic externality of global warming. This additional cost is born by the residents of the entire planet.

    Alternative energy producing solutions such as wind and solar electricity do not have the externality of global warming but face the alternate problem of intermittent supply. Despite massive research efforts in the production of better energy storage methods, the storage solution is not at hand. This is a flaw in the product.

    The nuclear alternative has the advantage of producing power 365 days a year and 24 hours a day without the global warming economic externality.

    As Rod has discussed in the past, the real obstacle to the nuclear alternative is fear and doubt. Fear can be a powerful demotivator to the technology’s success. The recent news about the Coronavirus has certainly provided an excellent example of the power of fear. I believe science will quickly find a vaccine that will alleviate that fear. That vaccine, when available, could possibly be pointed to as an analogue to the new nuclear technologies that when adopted may also alleviate the fear of nuclear power.

    Per Engineer-Poet’s discussion the new nuclear alternatives would provide an inexhaustible source of energy. In then tone of Rod’s article above, this is something to get excited about.

  4. @Rod

    TRISO is expensive by virtue of the vacuum vapor deposition processes used to make it. It should be obvious that encapsulating grains of HALEU-O2 in alternating layers of graphite, and SiC, built up atom-by-atom, molecule by molecule, at high temperature in hard vacuum is an energy intensive process second only to the cost of enriching to 20% and throwing away +45 tons of tails in the process.

    I didn’t dig up a reference to back up my statement about cost of TRISO. I welcome any economic analysis on the subject. Please share.

    HTR-10 is NOT ‘large enough to minimize the effects of leakage’… in fact the reactivity is dominated by leakage and that is why the enrichment is +10%. If you look at all the pebble bed course they are very long cylinders some of them have an annulus in the middle. They are tall and have a high axial aspect ratio where radius << height. As you know, this is to help dissipate decay heat in the radial direction, while keeping peak pebble temperature below 1800C or so… you will find in textbook 101 that right circular cylinder is next best thing after impractical spherical geometry for conserving neutrons. It's all about the ratio of volume to surface area; it is clearly optimum when the surface area is at a minimum and the volume is at a maximum. Long skinny cores of graphite where neutrons need 60cm to slow, are leaky and very suboptimal.

    1. @Michael Scarangella

      Pretty sure the apparatus I saw depositing TRISO layers and producing coated particles didn’t resemble your process description. My tour was conducted around 2006.

      I didn’t say HTR-10 was the correct shape to minimize leakage. I said it was big enough. Tall, slender cores are common designs, but not only options. Passive safety doesn’t mean you cannot use some convective heat transfer.

      1. We should find out how much the Ft. St. Vrain core cost….

        The OKLO FSAR[lite] is now available…


        There is a lot more detail in the PRISM PSAR, and we all know how far it got into approvals.


        We’ll see where the OKLO application is in 2 years; we’ve got some waiting to do… Nobody is going to be right or wrong overnight on this one…. Build one out there in the high desert of Idaho at whatever costs, and subsequent copies still have to deal with the inconveniences of economics.

        If there were any reason to build a 4MW liquid sodium reactor in the last 50 years, it would have been done. It took vision to attempt to license interstate highway-capable rollerskates.

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