Earlier quoted context omitted.
Total includes scattering which isn't a loss mechanism. Best bet is to do a spectrum weighted 1-group macroscopic absorption XS (including all neutron loss mechanisms) in various reactors for a meaningful comparison. Most nuclear textbooks have these in the appendix. All I'm telling you is that boron is used for control in fast reactors. I think you asked how it was done a while back. I kept reading about all these a…
RE "This kind of reactor needs enrichment once (to start up) and then can just be fed natural, DU, or SNF and it will run on a stream of it happily "forever" (until the vessel life is reached, at which point you transfer the core to a new machine and keep on shuffling)" As fission product concentration increases, even fast reactors have to remove fuel and reprocess it. What works for boron also works for fission prod…
Of course. This kind of thing is very well established things like [1]. TWR is not interested in burning SNF, that would require reprocessing to convert it from oxide in the first place. Reprocessing is expensive and has historical proliferation concerns. TWR's entire purpose is to approach closed fuel cycle advantages (Gen-IV safety, sustainability, cost) without needing any reprocessing whatsoever. It's a natural step after the US CRBRP mega-boondoggle. Don't reprocess SNF, bury it in geologic repositories and/or boreholes. Burn U-238 at global scale. That's the idea there. It's called a Modified Open Cycle, or Deep-burn once-through fuel cycle.
> Fluid-fuel can be used indefinite time and it is easy to reprocess liquid fuel by any method. There is no crystal structure to get damaged.
Fluid fuel trades solid fuel performance challenges for chemical/corrosion challenges and radionuclide containment challenges. At MSRE, ORNL has yet to account for about 50% of the radioiodine produced. No one knows where it went. that's a huge but not impossible challenge. I agree with the "Easy to reprocess liquid fuel" advantage, but recognize that it is also a proliferation disadvantage.
> Just throw away the hot leg plumbing and heat exchangers every 2.8 years initially (MSRE salt loop was circulated for 2.8 years) and increase this incrementally. These are rad waste remote operations, which has step influence on cost. What's the operational cost of this at FOAK? What's the operational cost at NOAK? It may be very cheap (Thorcon is well on their way to this) or it may be prohibitively expensive. The only way to really find out is to build and operate such a reactor commercially. To this end we will all benefit.
> Why point fingers at MSR folks when solid-fuel reactors throw away stuff? Who's pointing fingers? I mentioned downsides to all forms of reactors in the parent comment. MSR is wonderful and exciting and we as a community need to build many more of them and shake them down.
[1] https://www.iaea.org/publications/7112/implications-of-parti...