Beery wrote:Yeah, I mist admit, I know next to nothing about the issue. I was just looking to see if there was anything to the thorium thing - casting a critical eye over the whole thing, and the materials expanding and contracting problem just really struck me as the potential 'achilles heel' - especially since they seemed kinda cagey and dismissive about the solutions.
I'm not entirely sure what you're talking about. We know how to build a number of different types of fluid fuel reactors today, and have built several in the past. The only unresolved issues we currently have are what engineering compromises we are forced to take and what we can solve. We can use graphite moderation to reduce fissile load and make the core more compact while reducing the cost of the initial fissile startup cost, but then we have to deal with the neutron wear on the moderator causing swelling in the graphite. We don't have to use graphite moderation (and I'm convinced that eliminating the graphite moderator is a good idea) and that means a higher fissile load. Perhaps you were thinking of the graphite swelling?
We can use a simple two fluid reactor with nearly no neutron erosion of the outer wall with a sacrificial barrier that exists in a hell of neutron radiation that must be replaced every ten years or so, or we can have a single fluid reactor with highest neutron flux around the moderator with a much more complex reprocessing scheme. We could use a very large thorium containing blanket volume or we can use bismuth reduction to extract and partition the protactinium for the breeding to reduce the blanket volume.
There isn't anything that we fundamentally don't know if we can do or any unresolvable issues. The largest unknowns are which compromises are the least costly.