It appears you guys are more knowledgeable and more up-to-date on this issue of fission product regeneration for thorium reactors, so I'll tentatively accept your conclusions for the time being.

I have another question. You call these "fast reactors", so I'll assume you mean they employ fast, as opposed to thermal, neutrons for the chain reaction. My only experience in this regime were the breeder reactors which were experimented with in the 60s and 70s, which used liquid sodium as a moderator/coolant and generated steam through a heat exchanger. These were demonstrated to be feasible, but were eventually abandoned because of the potential hazards of having molten sodium circulating through a cycle which would have it come dangerously close to superheated water at one end and fissioning fuel rods at the other. The other hazard was that in this environment, a transient loss of moderator (such as a bubble or turbulence) would create a local environment where the reaction would increase, creating a larger bubble, which would create an increased reaction rate, etc. In short, it would be inherently unstable as opposed to a water moderator, where a bubble would decrease the fission rate and tend to damp out bubble formation. Could one of you folks comment on how any of these concerns relate to thorium reactors?