On Tuesday afternoon, Aug. 23, an earthquake of approximately 5.8 magnitude sent ripples throughout the east coast from its center in Virginia. While tremors were felt from New York to South Carolina, no major injuries or extensive damages were reported. Nevertheless, many were curious about the effects of the earthquake on nuclear power facilities in the Southeast.
A Dominion-operated nuclear station, North Anna Nuclear Power Plant, was less than 20 miles from the epicenter of the earthquake. Per design, the plant shut down after detection of the first tremors. All U.S. nuclear power facilities have seismic monitoring equipment which, upon detection of levels above the plant’s “trigger” for ground acceleration activity, alert operators in the control room, who then follow plant operating procedures regarding any needed actions.
Some people in the Carolinas felt the subtle quivers from the Aug. 23 quake, but the seismic activity in the areas surrounding Duke Energy's three nuclear facilities was not significant and had no effect on plant operations or equipment. However, personnel performed inspections and walkdowns as a conservative safety measure. U.S. nuclear power plants are designed with earthquakes in mind. They are built to withstand earthquakes with the magnitude equivalent to or greater than the largest known earthquake for the region where they are located, with margin beyond the plant’s design basis.
Containment buildings (which house the reactor, steam generators and other vital plant equipment) are among the most robust structures in the world. The buildings sit on foundations of bedrock and sand, designed to absorb tremors and shocks. Fortified by walls of three feet or more of steel reinforced concrete, containment buildings can endure tornadoes, fires, earthquakes, floods and a slew of external forces. Plant personnel are also extensively trained and prepared to handle natural disasters.
Reactor operators are continuously trained and tested to respond to natural disasters like earthquakes. Operators train for natural disasters and other potential plant challenges on control room simulators and are tested, along with the rest of the plant, on their ability to handle abnormal and emergency situations during drills and exercises, at least five times a year. These exercises are conducted with local, state and federal emergency management officials.
This year, nature has tested the U.S. nuclear industry's preparedness to withstand powerful natural forces in the form or tornadoes, flooding and most recently, an earthquake. Every nuclear station in the path of these challenges has successfully shown U.S. nuclear facilities are prepared to meet challenges that come their way.
Further Reading:
- Nuclear Energy Institute Comments on Tuesday's Virginia-Centered Earthquake
- Nuclear Plants Designed and Constructed to Withstand Earthquakes - NEI Factsheet
- US Geological Survey's (USGS) Details on Virginia's Earthquake
