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> a 50MW navy reactor has basically no decay heat Not necessarily: It depends on the power level the reactor was run at, and for what period of time. [0] > th

> a 50MW navy reactor has basically no decay heat Not necessarily: It depends on the power level the reactor was run at, and for what period of time. [0] > they just didn't internalize how much heat was actually still being produced It's not apparent that this was actually the case. I found this explanation, which makes sense to me (although I stress I have no particular knowledge of the incident): "... the [TMI] plant crew’s response was guided by wisdom received from another domain [i.e., Navy submarine plants]. ... They were under strict guidelines to never let the pressurizer go solid [which can be catastrophic in a submarine], and yet it was. The internal stress to meet this guideline was so severe, they left the rails and violated another guideline (shutting down the ECCS)." [1] This actually reinforces my basic point above about the undesirability of putting pressurized-water reactors near civilian population centers: Human error is inevitable, and it's undesirable to have a system where such errors would be catastrophic if compounded — and human error can indeed come in multiples, with each error compounding the effects of earlier ones. Here's a follow-up piece from the same author, about the effect confirmation bias at TMI and Fukushima (quoting another person): "Every reading that was true and really bad, they thought of as erroneous. Every reading that was erroneous but really good, they relied upon. That’s a trend that I always see in emergency response. Operators want to believe the instruments that lead them to the conclusion they want to get to." [2] [0] https://www.quora.com/How-much-time-does-it-take-for-a-nuclear-reactor-to-cool-down-after-a-shutdown-What-will-be-the-source-of-heat-as-fission-will-not-occur-after-the-shutdown https://www.quora.com/How-much-time-does-it-take-for-a-nucle... [1] https://learn.microsoft.com/en-us/archive/msdn-magazine/2016/may/editor-s-note-going-solid https://learn.microsoft.com/en-us/archive/msdn-magazine/2016... [2] https://learn.microsoft.com/en-us/archive/msdn-magazine/2016/june/editor-s-note-cognitive-bias https://learn.microsoft.com/en-us/archive/msdn-magazine/2016...

XorNot 3y ago
> a 50MW navy reactor has basically no decay heat > Not necessarily: It depends on the power level the reactor was run at, and for what period of time. [0] Yes it does - but the TMI plant was producing about 6% of its output power when it was put into shutdown, which is about 50MW - i.e. the full power of a much smaller Navy reactor.
- dctoedt 3y ago
  > the TMI plant was producing about 6% of its output power when it was put into shutdown, which is about 50MW - i.e. the full power of a much smaller Navy reactor. Are you taking heat density into account? An analogy comes to mind from summer outdoor-grilling season: A tiny chunk of glowing-hot charcoal doesn't produce nearly as much heat as does a bonfire, but the chunk of charcoal will still burn your hand pretty catastrophically.

XorNot 3y ago

> a 50MW navy reactor has basically no decay heat > Not necessarily: It depends on the power level the reactor was run at, and for what period of time. [0] Yes it does - but the TMI plant was producing about 6% of its output power when it was put into shutdown, which is about 50MW - i.e. the full power of a much smaller Navy reactor.

dctoedt 3y ago
> the TMI plant was producing about 6% of its output power when it was put into shutdown, which is about 50MW - i.e. the full power of a much smaller Navy reactor. Are you taking heat density into account? An analogy comes to mind from summer outdoor-grilling season: A tiny chunk of glowing-hot charcoal doesn't produce nearly as much heat as does a bonfire, but the chunk of charcoal will still burn your hand pretty catastrophically.