The overconfidence of nuclear engineers

Rumors that the Fort Calhoun nuclear power station is subject to a media blackout appear to be overblown, given that the NRC is blogging the situation.

Apparently floodwaters at the plant were at 1006 feet ASL yesterday, which is a fair margin from the 1014 foot design standard for the plant. That margin might have been a lot less, if the NRC hadn’t cited the plant for design violations last year, which it estimated would lead to certain core damage at 1010 feet.

Still, engineers say things like this:

“We have much more safety measures in place than we actually need right now,” Jones continued. “Even if the water level did rise to 1014 feet above mean sea level, the plant is designed to handle that much water and beyond. We have additional steps we can take if we need them, but we don’t think we will. We feel we’re in good shape.” – suite101

The “and beyond” sounds like pure embellishment. The design flood elevation for the plant is 1014 feet. I’ve read some NRC documents on the plant, and there’s no other indication that higher design standards were used. Presumably there are safety margins in systems, but those are designed to offset unanticipated failures, e.g. from design deviations like those discovered by the NRC. Surely the risk of unanticipated problems would rise dramatically above the maximum anticipated flood level of 1014 feet.
Overconfidence is a major contributor to accidents in complex systems. How about a little humility?
Currently the Missouri River forecast is pretty flat, so hopefully we won’t test the limits of the plant design.

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