1. Opponents of nuclear contend that recycling nuclear fuel creates a secondary waste stream, namely liquids and resins. They also contend that these waste problems are unsolvable. As with so many of their claims I have difficulty believing them. The impressive flux density of nuclear (as Brian Mays’ post indicated) combined with an equally impressive array of applications (desalination, hydrogen production, district heating etc.) demand that we recycle used fuel. Not doing so would be like buying 20 litres of fuel from a gas station and being told you can only use one litre of it.

    1. We also forget to talk about transmutation in te waste debate … Hey, the french went out for a bite (they have 3 hour lunches mind you) and tried bombarding neutrons on radioactive Technecium 99.

      When they came back, they had Technecium 100, not harmfull at all.

      So let’s not forget transmutation for liquids and resins.

      1. You wouldn’t have Tc-100; its half-life is only 15.8 seconds.  However, the decay product Ru-100 is stable, and Mo-100 has a half-life so long (8 billion BILLION years) it might as well be.

  2. If the process lives up to the promise, it might reduce investment interest in developing thorium based reactors.

    I don’t think so.  Fast-spectrum reactors do well at disposing of Pu and beyond, but need a high fissionables inventory so can’t scale up by breeding very quickly.  Thorium-based thermal breeders can be built with less than a ton of fissionables per GW(e) and may be able to breed up at 5% a year; U-Pu is closer to 2%/year†.

    The 60,000-odd tons of SNF in the US inventory has ~600 tons of Pu in it, enough to start maybe 30 GW(e) of LMFBRs.  That would be a big jump in US nuclear generation, but a long way from where we need to go.  The advantage is that it’s about as ready TO go as anything we’ve got; any US-built thorium MSR is going to take quite a bit longer to hit market due to 44 years of wasted time.

    The problem with Th-U waste is production of Np-237, which is fuel for the fast-spectrum reactors.  Thus, the fast-spectrum reactors still have a job even if thorium becomes free (as uranium from SNF and DU will effectively be).

    † The high inventory and consequent slow breeding rate is partly due to a projection of 3 core’s worth of fuel per reactor:  one in use, one cooling and one reprocessing.  If the cooling period could be shortened and the reprocessing cycle staggered with another reactor or two, maybe the inventory could be reduced and the growth accelerated.  If you can get the increase up to 3% of inventory per year, the doubling time falls from 35 to 23 years; at 4%/year, it falls to 18 years.

    1. Hello,

      By the way: Has anyone here ever heard of this idea: A molten salt reactor with lead cooling in the fast spectrum? The source I stumbled upon promises a 4 year doubling time and an EROEI of over 2000. They call it Dual Fluid reactor.

      A quote:

      “The efficiency of the MSR is reduced by the double function of the fuel to act also as coolant. As a result, the molten salt used had to be diluted in order to limit the power density, otherwise the heat could not be removed fast enough. Furthermore, salts with low melting point are necessary for the effective utilization of a heat engine. In addition, the salt has to circulate fast for efficient cooling and that, in turn, prevents any on-line reprocessing of the fuel. The fuel, thus, needs to be processed off-line (but still on-site) at regular intervals. Off-line processing of the fuel requires long shut-downs, further reducing the efficiency of the overall system.”




      Is this a new idea? It sounds too good to be true. Where are the downsides? Are there other sources about this reactor?


      1. I’m not a nuclear engineer, but I can think of a number of engineering difficulties with this concept:
        1.  Possible corrosion of the salt container by the lead alloy coolant.
        2.  Damage to the heat-transfer materials by fast neutrons.
        3.  Scheme allows the possibility of a loss-of-coolant accident.

        If I understand correctly, a fast-spectrum molten-salt reactor almost requires the use of molten chlorides, not fluorides.  Using the fuel salt itself as the coolant eliminates any issues of heat transmission from salt to coolant, and also of loss of coolant.  Whether there are major advantages to be gained from the complication… I am not qualified to give an opinion.

    2. The Indian PFBR uses 2 tons of Plutonium for 500MW of power. This gives 4 tons/GW. Even if we consider the PHWR plutonium to be better than the plutonium from LWR fuel, 5 tons/GW should suffice. That gives 120GWE of fast reactors in the initial build, nearly equal to present installed capacity of LWR’s in the US. Things are more economical in bigger reactors or in the MSR.
      The best solution in any case is fast spectrum MSR as the gen IV reactor.

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