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19 Comments

  1. Rod,

    Can you elaborate on the techniques / ideas that Prof. Zhang Zuoyi has to cut the cost in half and how long it will take to achieve that cost reduction? For the sake of comparison, did he happen to mention the cost of power production in China (so we could make a statement such as “the 2000-2500 $/kw of capacity using a HTR-PM is X times the cost of capacity for the coal unit it is replacing”)?

    1. @RTK42C

      Prof. Zhang Zuoyi is no longer an academic who freely shares everything he knows. He is now a businessman who understands that some information is too valuable to share for free. Specific costs, supply chain details and cost reduction strategies are among the closest hold topics for commercial enterprises.

      1. Well, seeing as he *did* give out that specific cost for the first-of-a-kind build, it seems like that should at least be possible to compare to the costs for coal in China? Or are the coal costs closely guarded secreets?

        1. A few years ago, I found article an article titled, “Economic potential of modular reactor nuclear power
          plants based on the Chinese HTR-PM project”, with Zuoyi Zhang as a co-author. The paper can still be found on line and might be behind a paywall now, but I still have the full text.

          In that paper, their FOAK estimates are over twice that of a series built PWR, with the target dropping to about parity. The main cost driver for the FOAK are the pressure vessel, reactor internals, and steam supply equipment. In my opinion, their plan for dropping that cost is through economy of scale of those parts.

  2. While this won’t save jobs in coal mining and transportation, this could save some jobs at coal power plants. I have an uncle who recently retired from working at a coal plant, and I know there was concern within the power industry at lost jobs from closing coal plants.

    Granted, it’s probably going to require retraining much of the staff, because nuclear technology is a bit different than coal, but these conversions could allow a lot of power plant jobs to be retained, seems like.

    That would probably be welcome news to some people.

  3. Rod,
    I note the potential for hydrogen production to change the greenhouse gas emissions and global warming causation of existing steel production with this technology. Please refer to a very good paper by Viktor Sivertsson from Uppsala University on Hydrogen production using high temperature nuclear reactors A feasibility study. In this article he compares the benefits of technologies such as high temperature electrolysis with sulphur – iodine

    1. I think you are on to something. It seems like a natural that process heat for industries should quickly follow once the Chinese begin building these things. I also wonder if the plants can receive uprates. Will it be possible to run the hot gas produced by the reactor through a Brayton cycle turbine with the hot exhaust gas then used in a steam generator like a natural gas cogen.

      Necessity is the mother of invention and the Chinese have the necessity to clean up their air.

  4. An alternative is a 12-pack of the forthcoming Nuscale modules @ 50 MWe apiece. Cannot reuse the steam equipment but can use the existing electrical equipment at the site. The estimated price is the same, US $5/W, and the estimated total time to mechanical completion is but 51 months from licensing.

  5. These PBMRs are reminiscent of the British AGRs, which were likewise graphite moderated, gas cooled, ran at about 600 C, and were built in pairs to give coal-quality steam. Both types are too large to qualify as Small Modular Reactors. Hence maybe the decision to place them in circles, not in rows – a few of the SMR designs have a row of reactors all under one gantry crane, but these things are too big for that.
    The AGRs get about 30% better thermal efficiency than light water reactors, but have a lower burnup on the fuel. They were also designed to be refueled at full power, which proved troublesome because of vibrations in the fuel assemblies. The German pebble bed reactor prototype had refueling problems too, with pebbles sticking in the chute. Hopefully the Chinese have sorted this out, so they might get a higher capacity factor than light water reactors, plus perhaps two or three times a LWR’s burnup by recycling pebbles back through.
    Did Prof Zhang say what enrichment the fuel will have, and what burnup they are expecting ?

    1. @John ONeill

      Yes, the HTRs have evolved from the AGR line of thinking, with design choices intended to address areas where the AGRs had issues. (It’s worth noting that many of the AGR issues have been mitigated; most of them are still operating today, routinely providing about 15% of the UK’s electricity.)

      AGR burnup is limited by low enrichment and by material limitations of the fuel assemblies. HTRs have TRISO coated particles designed to vastly improve fuel durability and they use higher fuel enrichments – nominally 9% fissile. (German AVR testing included all possible fissile isotopes.)

      The pebble form puts the moderating graphite into the fuel element and avoids many of the problems associated with the monolithic graphite structure cracking and swelling that has limited AGR performance and projected longevity.

      Fuel pebble handling systems have been refined and improved over the AVR. They still might have some operational issues, but not show stoppers.

  6. Using these type reactors to “re-power” existing power plant.s for me is where the money will be in the future. As stated in the article the capital has already been sunk for the TG sets turbine hall switch boards transformers etc therefore you are only paying for the steam generators and reactor which even on a LWR may only be 50% of the cost.

    As a stand alone new build I struggle to see the economics of gas cooled reactors compared to a LWR plant due to the higher cost of the reactor compared to the LWR otherwise AGR reactor would have been significantly cheaper than a LWR back in the 70’s (in the end costs were probably comparable)

    There are substantial savings to be made using conventional steam turbines compared to the low temp wet turbines used on nuclear plants which are generally one off custom built and very expensive in comparison, however this doesn’t tend to make up for the higher reactor cost due to low power density.

  7. Excellent report Rod, very informative as always.

    It will be interesting to see if the new U.S. administration takes up the recommendation of the SecE task force report on the future of nuclear energy, with this technology being highlighted ( at least initially ) as one of the most advanced , – along with the sodium fast design.

    I also read your brief on who may be appointed as the new SecE , very interesting !

    Diarmuid

    1. @benjamin weenan

      Modern CCGT’s operate with turbine inlet temperatures in the range of ~1500 ℃. The highest proposed MSR reactor outlet temperatures that I am aware of are in the range of 700 ℃. Unless you are willing to accept a substantial boost from natural gas combustion to raise turbine inlet temperature to the 1500 ℃ range, you would be better off using MSRs in supercritical steam plants or in old fashioned gas turbines that don’t have exotic materials, blade cooling systems and compressors that produce pressure ratios in the range of 25:1.

      Here is a useful article from Power Engineering describing the evolution of high efficiency CCGTs. It includes a discussion about the steps used to increase turbine inlet temperature from ~540 ℃ in the late 1938s to the 1500 ℃ used in CCGTs that approach thermal efficiencies of 60%.

      http://www.powerengineeringint.com/articles/print/volume-18/issue-3/features/ccgt-breaking-the-60-per-cent-efficiency-barrier.html

      1. Or you could use a helium gas reactor & turbo-compressor to drive the gas turbine’s air compressor, yielding a ~959 MWe power plant using an advanced gas turbine like a GE 7HA. Yields the cleanest and most efficient fossil power plant ever proposed. All this from a single gas turbine and steam turbine.

        This objective of the technology is to significantly improve a gas turbine while using a simplified helium gas reactor (~630 MW thermal). Natural gas or coal gas can be used.

        Relative to an existing coal plant, everything but the switchyard and coal handling equipment would have to be junked – would also need a relatively small gasification plant. However, emissions end up being about the same as a natural gas fired gas turbine.

        This is a patented US developed technology.

        1. @Mike Keller

          Your proposed system seems quite complicated and filled with new components that have to be developed and tested.

          Good luck.

          1. The only new item is a helium turbo-compressor, which from a process industry standpoint is pretty straightforward.
            Everything else is an adaptation of existing technology.

            Also, can provide power using steam turbine without the gas turbine and reactor, which yields a very reliable plant. A bypass stack and forced draft fan are used with the Heat Recovery Steam Generator. Have managed plants like that and we routinely switched back & forth on the fly.

            Providing steam to a single turbine using a number of reactors is operationally complicated –also not allowed in the US by NRC regulations.

            Also, using a gas reactor to drive an existing coal boiler’s super-critical steam turbine is not a very good fit for a variety of thermodynamic and design reasons. The superheat/reheat conditions do not fit very well with the reactor’s boiler. Better to use a steam turbine designed specifically for the gas reactor.

            1. @Mike Keller

              Unlike China, the US doesn’t have a large inventory of nearly new super-critical steam plants whose steam conditions almost exactly match those available from HTR-PM modules.

              The HTR-PM is a step towards resolving the “operationally complicated” task of supplying steam to a turbine from multiple passively safe reactors that can be continuously refueled while operating.

              I’m not sure why you say regulations in the US would prevent such a system from operating here. Obviously, there are no current regulations covering such a system, but that is true of almost every reactor technology other than light water cooled and moderated systems that are only refinements of currently operating reactors.

              As I said before, good luck to you and whatever team you are working with on this project. It seems like a worthy effort that will have plenty of challenges.

  8. Ever wonder why NUSCALE is using one steam turbine per reactor? Could use 2×1 configuration without too much trouble (kind of like what the Chinese are doing). NRC will not allow it – I suspect is a Reg.Guide and possibly the Standard Review Plan item. As near as I can tell, does not appear to be in General Design Criteria. Might be easier just to ask the NUSCALE folks directly.

    Operationally, when you string a bunch of boilers together, the various feedwater control and fuel control systems start chasing each other in response to changing steam conditions (transients). Much easier to just go with a 1×1 configuration from a simple operations standpoint.

    Ps I vaguely recall Enterprise had several reactors per steam plant. However, Navy is exempt from NRC requirements, thank God.

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