Up to now the 2014 Atlantic hurricane season has been pretty calm, but the NRC always keeps an eye out for the strong weather-related events and other natural events the world can generate. We make sure both U.S. nuclear power plants and the agency are prepared for high winds, storm surge and a whole lot more.
Most recently, the seven reactors affected by 2012’s Superstorm Sandy remained safe. Other plants have safely withstood powerful storms, including Waterford 3 in Louisiana handling the effects of 2005’s Katrina and Turkey Point in Florida safely taking a direct hit from 1992’s Andrew.
Flooding can happen with or without storms, and U.S. plants are designed to and safely ride out significant events, such as when Fort Calhoun in Nebraska dealt with an overflowing Missouri River in 2011. Also in that year, Vermont Yankee remained safe as the Connecticut River valley suffered severe short-term floods from Hurricane Irene’s remnants.
Japan’s Fukushima Dai-ichi nuclear accident in March 2012 showed the world what flooding (in this case from a tsunami) can do to a reactor. The NRC’s learned several flooding-related lessons. from the accident. As a result of NRC direction, U.S. plants are using the latest software and technical know-how to re-analyze all flooding sources. This will help the NRC determine if the plants need to consider higher flooding water levels when establishing plans to stay safe. This effort has also examined existing flood protection and all plants have taken steps to confirm they can implement reliable flood safety plans. In the meantime, several plants have also chosen to enhance their flood protection.
An earthquake caused the tsunami that devastated Fukushima, and again U.S. plants are designed to stay safe in the face of quakes that affect their area. Virginia’s North Anna plant was hit by an August 2011 quake centered a short distance away. The earthquake was strong enough to be felt across the East Coast; it shook North Anna with a little more force than what the plant was originally designed to withstand. North Anna remained safe – multiple inspections showed the plant’s systems were undamaged. This was unsurprising, since plant systems are designed to withstand a combination of events that can exceed the forces generated by an earthquake alone.
As with flooding, the NRC has learned from Fukushima’s quake and other recent earthquakes, and we’re having every U.S. plant reanalyze earthquake hazards to see where enhancements might be needed. All the plants east of the Rockies have taken the first step in that process, and the other plants will do the same next March.
U.S. reactors are also designed for (and have safely survived) hazards such as tornadoes, droughts and other severe weather events. Even with all this preparation, Fukushima reminds us to prepare for the unexpected. The NRC’s approach here involves every U.S. reactor having additional portable systems to restore and maintain safety functions.
All of this work helps ensure the public stays safe when natural disasters strike that may impact U.S. nuclear power plants.