U.S. nuclear energy facilities are highly unlikely to experience the devastating combination of a massive earthquake and tsunami that crippled the Fukushima Daiichi power plant in Japan, but the events there underscored the need to guard against even very unlikely combinations of extreme natural forces.
The nuclear energy industry agrees with most issues the U.S. Nuclear Regulatory Commission has identified since Fukushima to complement existing seismic and flood protection programs.
The American nuclear industry didn’t wait for the NRC to take action after Fukushima. Within days of the disaster in Japan, plant operators began triple-checking the capability of America’s reactors to withstand extreme natural events. Specific actions included verifying that vital materials and equipment are properly protected from floods, earthquakes and other natural phenomena. To further ensure safety, the industry supports additional steps, such as:
- conducting more comprehensive inspections of seismic and flooding protection to identify and correct plant-specific vulnerabilities
- evaluating new seismic hazard information and, where appropriate, implementing plant modifications to enhance seismic safety
- establishing protocols for evaluating significant new information related to earthquakes and floods as that information becomes available.
“On an ongoing basis, the industry verifies each company’s program for monitoring and maintenance of protection against earthquakes and floods,” said Tony Pietrangelo, chief nuclear officer at the Nuclear Energy Institute. “Initial plant designs were conceived with a built-in margin of safety greater than the largest earthquake and flood ever known for the region. These robust design standards, which already protect against extremely rare forces of nature, are further strengthened by this extra margin of safety.”
A Proven Track Record of Success
Thanks to the industry’s scientific research and extremely strong plant design and construction, nuclear energy facilities have repeatedly withstood nature’s wrath.
When Hurricane Katrina slammed into the Gulf Coast in 2005, the Waterford nuclear energy facility, just 20 miles from New Orleans, bore the brunt of the storm. The plant shut down safely, according to its license guidelines, and relied on emergency diesel generators for four and a half days until power from the grid was restored.
When a series of tornadoes destroyed transmission lines and ravaged the area around the Tennessee Valley Authority’s Browns Ferry reactors in Alabama earlier this year, all three reactors shut down safely and seven huge emergency generators supplied backup power – all according to plan.
Also, when the Missouri River rose to record flood levels this summer, two reactors in Nebraska took measures to remain safe. The Cooper Nuclear Station remained at full power and secure with all vital and safety systems dry and operable. The Fort Calhoun nuclear facility was already shut down for refueling and maintenance, and protective measures kept the plant safe despite floodwaters that surrounded the site.
And, most recently, when an earthquake struck Virginia this summer, the North Anna Power Station, just 11 miles from the earthquake’s epicenter, safely shut down. According to plan, locomotive-sized diesel generators kicked in to power critical safety systems. Even though the ground accelerations from the earthquake exceeded the design parameters of the plant, the facility did not sustain any serious damage.
“You’d expect to find damage; the reality is we have found nothing,” said Eugene S. Grecheck, vice president for nuclear development, Dominion Virginia Power, during his remarks at the Governor’s Conference on Energy on October 17.
“The plant actually rode it out very well as far as we can tell today,” said Martin J. Virgilio, the NRC’s deputy executive director for reactor and preparedness programs, who also spoke at the conference.
All U.S. nuclear plants were designed to withstand the strongest historical earthquakes and floods at the plant site and the surrounding area, with an additional margin of safety to guard against the unexpected.
As part of an effort that began in 2005, industry and the NRC are currently evaluating the effect of new seismic hazard information on plants in the central and eastern U.S. The industry will continue to work with the NRC to ensure that an appropriate safety margin is maintained.