1. Ran across an Ian Scott You-Tube the other day:

    Scott is a principal at Moltex Energy: http://www.moltexenergy.com/ — they are developing a “stable-salt” MSR. Scott observes the principle difference between applying pyroprocessing to metal-fuel SFRs where the technique was originally pioneered, and U-Pu fueled MSR, is that pyroprocessing should in principle be much simpler with the latter.

    1. All advocates of MSRs have been banging on about the cost savings that reprocessing straight from a salt fuel would bring, as cuts out the initial steps .

      If can be done cheaply enough, perhaps why bother with the online processing?

      1. I like the moltex ideas. Wonder if they need online removal of Cs from coolant salt which would get there via Xe. Half lives of 133 135 and 137 Xe are 5.5d, 9.5h and 3.8 min so quite a bit would come out due to open venting af the fuel tubes.

    2. Reprocessing might be easier for the fuel salt, but the table on the first page here
      is rather sobering. Starting with 20% U (presumable repu) and 20% reactor grade Pu (hence 12% fissile) and fissioning 5% they end um with 15% Pu 18.5% U and 1.5% m.a. (not sure how they get 1.13% Np). So for 5 percentage point fissions they loose about 3 percentage points fissile material and even with perfect reprocessing, they would only get 1.6 fissions out of each fissile input nucleus. This is a rather greedy burner and not a breeder. Not much better than a LWR, in fact.

      From a fast reactor, we should expect much better. It appears the neutron economy with salts is just not good enough.

      Note also how transatomic power in their latest white paper went from the original claim of running on a LWR waste actinide mix with 1.8% fissile content to running on nice and tasty 5% enriched uranium, and benefitting from topping up with 20% enriched uranium. Given they, unlike Moltex, use Litium in the salt, the claim of significant fast fission in some unmoderated regions was never credible. Litium itself is too much of a moderator.

      All this highlights the huge importance of the work that was done on the IFR, which really does allow breeding.

  2. Pyroprocessing is the most important nuclear technology now, even more important than advanced reactors, because most of the advanced reactors depend on reprocessing in one way or another. Aqueous reprocessing has reached its limits and can’t be considered as a stage in any realistic attempt at closing the fuel cycle. Pyroprocessing holds promise for becoming one of the pillars of the plutonium economy.

      1. Aqueous reprocessing generates large amounts of low-activity water, which has to be dumped somewhere. While I can agree that it doesn’t pose any immediate danger, it raises questions about the scalability of the technology. It also creates bad public image of reprocessing as something inevitably polluting. Closed fuel cycle implies that the fuel has to be reprocessed many times in a short time span. If doing so produces any significant enviromental impact it sort of defies the point of closing the cycle. We better have a repocessing technology that keeps all the waste in the system. Luckily, we have pyroprocessing.

  3. Rod Adams wrote:
    As envisioned, pyroprocessing would also enable material from used fuel rods to be promptly transformed into new fuel rods, thus addressing the contentious issue of building up large stockpiles of material that could be converted into nuclear weapons.

    Two things:
    1. The two outputs of pyroprocessing are mixed actinides, and everything else (fission products, mainly). The mixed actinides are not bomb making material. In theory, bomb grade material could be separated out, but there are easier ways of making a bomb.
    2. Where would the mixed actinides be used? Recycling LWR fuel would yield a lot of U238 in the mix. This mix would be useful to dilute highly enriched uranium from decommissioned weapons, but there is not that much of this stuff around. We need reactors (such as the IFR) that can use the mix as the main input to replace the fuel burned by the reactor.

    1. Indeed. Factor in the depleted uranium-238 left over from enrichment, and we can increase Rod’s 70-year supply estimate on recycled LWR fuel by a factor of ten in fast-spectrum reactors, be they sodium, lead, or molten salt.

      One (not myself of course, but someone) might speculate such is another motivation of those opposed to pyroprocessing “for anti-proliferation” reasons. “Dangerous radioactive uranium mining” is a frequent calling card of the renewable fossil-fuel environment industry. Being able to run the entire planet for a half millenium with no further fuel mining at all does not play into that particular narrative.

      Nor does seawater-extraction.

      1. @Ed Leaver

        The prospect of never having to mine the earth for new fuel is sure to upset many other apple carts. Drilling holes and excavating mining pits is BIG business. So is laying out the transportation and logistics effort required to gain access to productive areas and to move the raw materials to market.

        I like to think of what human society will be able to accomplish once we throw off the burdening notion that there is a serious limit on our potential to do work based on having a limited supply of energy fuels that are “going to run out someday.”

        1. Many green thinkers like Paul Ehrlich and Hoymar von Ditfurt had a strange aversion towards plentiful side-effect-free energy.
          The usefulness of these ideas would not have been lost to the profiteers of enegy scarcity.

        2. Rod: I, personally, am of the opinion that to get the most benefit from nuclear fuel, we need to close the fuel cycle, and put a moratorium on fuel mining eventually, at least temporarily (where temporarily is maybe a few hundred years – so that we can burn down our already mined stocks of SNF and DU).

          The reason I suggest a moratorium (this would have to be phased in, with a date set in the future from when it is passed as law, so that existing nuclear plants could continue to run and be able to buy new fuel, until the completion of their lifecycle), is because of the problem that, at least when recycling first starts, it’s expected to be a bit more expensive than newly mined fuel.

          It seems to me that, if I understand the economics correctly, the more expensive recycled fuel wouldn’t make nuclear energy much more expensive – but just enough that if a competitor can use newly mined fuel instead of recycled, they would have an advantage over you, so that it essentially forces everyone to buy new fuel because it’s the cheapest option. But, if the higher cost of recycled fuel is required of everyone, then everyone will do it.

          Once you do that, then the learning curve kicks in and the cost of recycling gets lower, maybe to about the same as newly mined uranium, or hopefully substantially lower – the hope would be that with recycling, you could avoid the millions or billions per year that would otherwise be spent in mining, transportation, milling, refining, enrichment, manufacturing, etc.

          Yeah, that would upset those who would like to get that revenue, but the goal is that the revenue would be re-allocated in the economy in such a way that it provides other jobs in other industries, lowering the cost of energy from nuclear.

          Eventually, of course, you’d need to allow new mining, extraction or importation of fuel, because after a few hundred years, you’d start to draw down supplies. I’d say it’d be good to always keep a few decades’ strategic reserves on hand.

          1. @Jeff S

            I don’t agree with your initial premise. My goal for a power system is to provide clean, safe, affordable, and reliable energy. It is not to “get the most benefit from nuclear fuel.”

            Though some people believe it is somehow wasteful or hazardous to stockpile slightly used fuel or completely unused potential fuel (DU) in containers on or near the surface of the earth, I’m not sure why.

            Those containers don’t take up much space and they are not posing any threat to any human that doesn’t mess with they using heavy equipment.

            There is nothing inherently wrong with mining the Earth for raw materials. Humans have been engaging in that endeavor for thousands of years and will never stop.

  4. Rather off-topic but today TNYT has an article “The Murky Future of Nuclear Power in the United States” by a Dianne Cardwell. The article contains several small errors but contains a few tidbits such as the NRC regulating backfill dirt!

    Possibly Rod would care to write a response here, with a shorter version as a letter submitted to the editor.

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