Good data, thanks. My U233 number was misremembered. I didn't mean to imply U233 was required for the Thorium reactors, only that it's a relatively 'natural' use for it.
China and India are presently building (or in late stage planning) experimental hybrid Uranium+Thorium reactors but I think they are both solid-core (and I'm too lazy to go look it up!)
The problem with yellowcake, of course, is the cost and proliferation risk of enrichment. Thorium needs no enrichment (other than the starter neutron source, and at least one research project is attempting to use a linear accelerator to replace that - we shall see how that pans out). Advocates of the Thorium fuel cycle also argue that the LTFRs have at least two orders of magnitude less potential for proliferation. I think that number may not remain at that level as real experiments and analysis of the complete lifecycle are done, but nevertheless it's a worthwhile prospect.
The fact remains that there are strong commercial pressures against LTFRs due to the profitability and barriers to entry for nuclear fuel rod manufacturing and reprocessing.
Finally, as a space development advocate but not a nuclear scientist, it seems to me that Thorium fuel cycle might be a much more attractive / less scary technology for space propulsion than Uranium fuel cycles - to the extent that it might actually be possible to get through the political hurdles (in some country) That's offtopic for this discussion so I won't get into it here.