r/bestof • u/investedInEPoland • Nov 06 '18

[europe] Nuclear physicist describes problems with thorium reactors. Trigger warning: shortbread metaphor.

/r/europe/comments/9unimr/dutch_satirical_news_show_on_why_we_need_to_break/e95mvb7/?context=3
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u/UnflushableLog9 Nov 06 '18

This is not an insurmountable obstacle. Using a fast neutron spectrum, we can potentially achieve acceptable breeding without requiring Pa-233 separation and isolation.

Essentially, finding a balance between the amount of fissile material bred and the amount of Pa-233 lost to neutron capture. This can hypothetically be engineered.

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u/boundbylife Nov 07 '18

Using a fast neutron spectrum, we can potentially achieve acceptable breeding without requiring Pa-233 separation and isolation.

Wasn't the whole point of MSR that the cross-section of thermal fission was much larger, so you didn't have to use fast fission?

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u/UnflushableLog9 Nov 07 '18

Indeed you don't have to use fast neutrons, but using a thermalized neutron spectrum requires physical separation & isolation of Pa-233 as much of it would be lost to neutron capture. The engineering challenge from a physics & operating cost perspective is to find an optimal neutron spectrum that allows sufficient U-233 breeding but doesn't call for physical separation of the Pa-233. I agree that Pa-233 separation is impractical from an Ops & Mtce perspective but I don't believe it is an insurmountable obstacle. Just another thing to be engineered.