@Charles BartonRob is quite correct that I had written of the Chinese PBMR in error, as I fpund when I looked it up on the Internet. The Chinese are building two comercialo prototype PBMRs,that will ge cooled by Hellium, and superheated water as a secondary heat transfer media. This project has been in the works for some years, and I simply assumed that it had been shut down. I was wrong as Rod pointed out. It is however still questionable whether the Chinese PBMR will ever go into commercial production.
I have not yet finished your piece, but I needed to take a break and respond to the following statement:
The Pebble Bed Reactor is often pointed to as an example of Generation IV Inherent Safety, but part of that safety requires a very large core. In fact a core that is larger than the core of commercial Light Water Reactors. The Pebble Bed core costs as much to build as a LWR and thus no one seems to be moving forward with conventional Pebble Bed Reactor projects.
You and I have had this discussion before; claiming that pebble bed reactors cost as much to build as an LWR because they have large cores exposes the simplistic nature of your understanding of cost drivers. Big structures are not necessarily more costly than smaller structures; there are many factors included in cost computations in addition to physical size. For example, an NFL football stadium is a much larger structure than the "nuclear island" of a large, 1000+ MWe class nuclear reactor, but even with all of the bells and whistles of modern stadiums, stadiums are considerably less expensive.
Your statement that "no one seems to be moving forward with conventional Pebble Bed Reactor projects" is a little exaggerated; there are two commercial pebble bed reactors under construction in China as part of their continuing methodical development of the technology. Those two reactors build on the lessons learned by ten years of operating the 10 MW experimental HTR-10.
Designated as HTR-PM, those two reactor cores are going to both provide the heat and steam for a single 210 MWe turbine. The choice to use two reactors to heat a single turbine helps to expose the complex nature of cost computations when you make a complete paradigm shift from a pressurized water cooled reactor to one that uses pressurized helium as the heat transfer mechanism.
Thank you Rod for pointing out my mistake.