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Sep6-11, 09:21 AM
P: 778
Quote Quote by gmax137 View Post
I'm pretty sure that 'ground acceleration' as a single value is not meaningful (in the context of the damage it can cause) without the corresponding frequency. In other words, a high acceleration at a high frequency may be much less damaging than a lesser acceleration at a low frequency. The seismic design is developed from a ground response spectrum, not a single 'g' value. Maybe someone with seismic design expertise could chime in here.
Yes, it turns out the plant was designed to withstand earthquakes with a long wavelength which are characteristic of west-coast earthquakes. However this earthquake was a short wavelength one, which is why the concern over design basis limits. Note that it is only the aux building sensors which may have exceeded the design basis earthquake, not the whole plant.

Another interesting tidbit: the dry storage casks moved several inches. Or from what I've been told, the casks remained stationary while the ground underneath them moved!

Here is a video in the Richmond Times Dispatch showing a brief tour inside the plant, if you've ever been curious what it looks like: