The plant had originally declared an Alert, the second-lowest of four emergency classifications, when it lost electricity from the grid following the quake just before 2 p.m. yesterday. North Anna’s onsite diesel generators provided power to the plant’s safety systems until grid connections were restored at approximately 5:40 p.m. that same day.
The plant downgraded to an Unusual Event at approximately 11 a.m. today, before canceling its emergency declaration altogether.
North Anna personnel are currently assessing the plant’s normal operating systems and structures. The NRC’s resident inspectors at the plant are observing the plant’s activities and providing first-hand information to the agency. In light of the quake’s strength and proximity to the plant, the NRC will soon decide whether to conduct a follow-up inspection, aimed at determining how the quake compares to what the plant was designed to withstand.
The NRC also contacted Eastern U.S. industrial and medical facilities that possess significant quantities of nuclear materials. All of these locations confirmed their materials are secure.
Twelve other Eastern U.S. nuclear power plants had declared Unusual Events while they examined their sites immediately following the quake. All 12 had canceled their event designations by yesterday night and all continue to operate normally.
Nuclear power plants are built to withstand environmental hazards, including earthquakes. Even those plants that are located outside of areas with extensive seismic activity are designed for safety in the event of such a natural disaster. The NRC requires that safety-significant structures, systems, and components be designed to take into account the most severe natural phenomena historically reported for the site and surrounding area.
The NRC is also continuing a multi-year effort to have U.S. nuclear power plants use advanced methods and updated seismic information to re-examine how the plants would respond to earthquakes.
Scott BurnellPublic Affairs Officer