Let's assume the North Anna plant was hit with 10 cm/s from an M5.8. That's really a small earthquake for disaster planning, and the zone looks like it can generate far greater, easily a Charleston M7 or thereabouts.
At 10 cm/s I believe a Mark 1 reactor (Oyster Creek) would have lost a few significant nozzles and be in a Japanese state. But this reactor is an old Westinghouse design, which can probably take 30 cm/s. But what about the diesel generators? They are always located on a crap foundation, much like the waste casks, which shifted 11 cm, but the diesels are usually anchored. I've never seen a nuclear diesel farm that can take 30 cm/s, mainly because of the rotten tanks, and el-cheapo block walls. I think the ground motion was very close to that on the diesel pad, and a close examination should show that the anchors pulled.
Thus, we must ask ourselves 2 questions:
What would have happened to a Mark 1 at this location?
How close was this to a disaster? -diesels shifting.
Because there were no instruments, we will never know, but I never let willful ignorance stop me! I'd say we'd be into a first class nuclear emergency if this had been an M6.5. The containment would hold, and lightly contaminate things. Had this been a Mark 1, an M6.5 would have blown it out of the water....