> But, for complete fission of SNF, fission-product removal is needed at some stage when fission product concentration exceeds a particular level in the fuel rod. No exception for travelling wave burnup.
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.
Both metallic fuel and salt fuel are not suitable for geological repository. Salt fuel may be stored in salt mines, but unproven. More R&D is needed for geological disposal; but, the point in having metallic fuel or salt fuel is the ease of separating fission products and reusing fuel, not geological storage.
Iodine:
Not 50%. It is a probability range. "Thus, of the order of one-fourth to one-third of the iodine has not been adequately accounted for."
RE: "but recognize that it is also a proliferation disadvantage"
MSR without reprocessing:
MSR can be as hardened as anyone wants. Because of liquid fuel-form, MSR can be sealed tamper-proof. Fuel goes in and nothing comes out during operation.
Safeguard scenario in case of maintenance:
By design the fuel will move to drain tank when shutdown for maintenance. IAEA can have the keys for the drain tank. Fuel can't be pumped back without the presence of IAEA inspector. If someone tampers this, license will be cancelled and the country will have no electricity.
MSBR with reprocessing:
How easy separation of fission products from denatured liquid-fuel can be a proliferation disadvantage? It is actually a advantage because fuel always stays inside a tamper-proof system. ORNL attached a "add-on" apparatus for fluoride volatility, and fuel always stayed inside MSRE building. This is actually an advantage.
As material science improves, MSRs last longer and longer without need for maintenance. Safeguards will also become less frequent and less expensive.
I strongly agree that MSR needs a chance. MSR graduated with excellent results with MSRE. MSRE has answered most of the questions and raised very few new questions. MSR should be given a suitable employment like process heat or medical isotope production as soon as possible. We can scale it up for electricity later on.
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...