LeadDev
4 HN recommenders · recommended in 4 months, 2020–2024
37:07 · 762K views · Mar 21, 2018
Nickolas Means recounts the 1979 Three Mile Island accident minute by minute, from the control rod insertion to the operator's decision to switch off emergency cooling. He argues that finding systemic causes is more useful than blaming individuals.
HN recommends it whenever a failure is blamed on human error, as a clear case study in looking for the systemic second story.
4 comments from Hacker News
There's an excellent talk from Nick Means (GitHub) called "Who Destroyed Three Mile Island?". Link: this video One thing it discusses is how the alerts inside the control hub were so noisy, and were logged via a reasonably slow printer, that the alerts which suggested the reactor was in serious trouble only printed hours after you could do anything. And the alert light that said "shits fucked" was placed right next to the light about an elevator being out of order. Human error is rarely intentional, and even if it is, a system that fails in response has missed the mark. The talk explains the amazing finds made by the government committee hired to investigate the incident, once they left the idea of 'human error' at the door. I do suggest you watch the video, but as a teaser: it turned out that at the time, most US nuclear engineers had been sourced from nuclear subs. Subs have totally different rules on how to manage the reactor, and train their staff inappropriately for a land-based reactor. Pretty significant cultural find...
Nickolas Means has an absolutely wonderful set of talks on themes like this. Particularly relevant here I think, is his talk: "Who Destroyed Three Mile Island?" - which goes through the events that occurred at the nuclear power plant, the systemic problems, and how to find the "second stories" of why failures occurred. this video
I'll have to dig up a citation. But the [] Three Mile Island accident was in part caused by (former) naval nuclear specialists making poor choices based on optimizing for the wrong things. My memory is fuzzy, but this 37 minute video [2] has a breakdown. If memory serves, the root causes were faults in the pumps and delays in the 28 baud diagnostic printouts running minutes or hours behind which left everyone operating on bad data. Part of that was exacerbated by the operators applying techniques used on subs (something about preferring to keep low pressure in some vessel, because high pressure there could sink the boat if containment was lost), the TMI design didn't need this as it could vent/blow-off, and the operators became somewhat fixated on "trying to save the boat" and missed a bunch of procedures. Of course this doesn't invalidate your point, but even if the reactor designs are really similar, it may be a mistake to cross train anyone. (disclosure: haven't seen this video in a year or so, and am generally a fan of nuclear power considering the alternatives, but it needs to be done with different, safer reactor designs and probably with new branding because no matter what it's going to take _forever_ to convince anyone to trust nuclear, when they associate that term with the dangerous, BWR designs that were never intended for land) [1]: [LINK] [2]: this video
Thanks for that, I really appreciated this breakdown of the accident at Three Mile Island and the concept of 'the second story' with regards systems thinking; this video