Why Nuclear Meltdowns Happen
Yesterday we learned from Malcolm Gladwell about why plane crashes happen. Surprisingly, “plane crashes are much more likely to be the result of an accumulation of minor difficulties and seemingly trivial malfunctions [as opposed to major mechanical failures].”
Interestingly, the same factors are at play in creating most major disasters and industrial accidents, including nuclear meltdowns.
The near-meltdown at Three Mile Island is a case in point. A number of minor errors that would have each been harmless in themselves combined to create a near catastrophe. In fact, even four of these errors happening together would have amounted to nothing. But with each error, there was some freakish, incredibly unlikely related error at just the wrong spot to render the previous error significant. After a sequence of five of these, the plant was almost at a meltdown.
The story is quite incredible. Here it is, from Gladwell’s book Outliers (p. 183):
One of the most famous accidents in history, for example, was the near meltdown at Pennsylvania’s Three Mile Island nuclear station in 1979. Three Mile Island so traumatized the American public that it sent the US nuclear power industry into a tailspin from which it has never fully recovered. But what actually happened at that nuclear reactor began as something far from dramatic.
As the sociologist Charles Perrow shows in his classic Normal Accidents: Living with High-Risk Technologies, there was a relatively routine blockage in what is called the plant’s “polisher”–a kind of giant water filter. The blockage caused moisture to leak into the plant’s air system, inadvertently tripping two valves and shutting down the flow of cold water into the plant’s steam generator.
Like all nuclear reactors, Three Mile Island had a backup cooling system for precisely this situation. But on that particular day, for reasons that no one really understands, the valves for the backup system weren’t open. Someone had closed them, and an indicator in the control room showing they were closed was blocked by a repair tag hanging from a switch above it.
That left the reactor depending on another backup system, a special sort of relief valve. But, as luck would have it, the relief valve wasn’t working properly that day either. It stuck open when it was supposed to close, and, to make matters even worse, a gauge in the control room that should have told the operators that the relief valve wasn’t working was itself not working properly. By the time Three Mile Island’s engineers realized what was happening, the reactor had come dangerously close to a meltdown.
Here’s the point:
No single big thing went wrong at Three Mile Island. Rather, five completely unrelated events occurred in sequence, each of which, had it happened in isolation, would have caused no more than a hiccup in the plant’s ordinary operation.
That is simply fascinating in itself. But let me be anti-climactic here by drawing out a lesson for our productivity.
Here’s the lesson: If you keep your routine systems humming along well (getting your email to zero every day, processing your inbox daily, etc.), who knows what far greater complications you may be saving yourself from?
By keeping the basics going along well, you may be heading off an accumulation of small complexities in your life which in themselves may not be a big deal, but which may just have ended up combining with a few other insignificant complexities to create a perfect storm. Perhaps not a nuclear meltdown, but perhaps a very, very bad day.