Reading in excess of 100 are examples where radiation levels are above and beyond basic background radiation
The Radiation Network website will automatically update the readings.
From Radiation Network:
Location of North Anna Power Station:
And a report from RobertSingleton:
Dominion Power notified the Nuclear Regulatory Commission that it had issued a Notification of Unusual Event (NOUE) at its North Anna nuclear power plant early yesterday evening after experiencing a 3.2 magnitude earthquake at the facility in Virginia. The NOUE was terminated just after midnight following a walkthrough inspection. Both reactors at the plant continued to operate at full capacity during the incident. The tremor is thought to be an aftershock from the 5.8 magnitude quake that shut down both units at the plant on August 23, 2011.