The Nuclear Regulatory Commission, after careful analysis of inspection findings and related information, has concluded Dominion Generation’s North Anna Unit 1 and 2 reactors can be restarted. The North Anna reactors, in Louisa, Va., have been shut down since Aug. 23, when a magnitude 5.8 earthquake occurred about 11 miles from the plant.
“The earthquake shook the reactors more strongly than the plant’s design anticipated, so Dominion had to prove to us that the quake caused no functional damage to the reactors’ safety systems,” said Eric Leeds, director of the NRC’s Office of Nuclear Reactor Regulation. “We’ve asked Dominion dozens of detailed questions, and our experts have examined Dominion’s answers as well as information from our own inspections. We’re satisfied the plant meets our requirements to restart safely, and we’ll monitor Dominion’s ongoing tests and inspections during startup of both reactors.”
The NRC issued Dominion a letter describing the staff’s review, which started with existing guidance for determining a reactor’s response to an earthquake. The staff used more recent experience, including insights learned from a reactor site in Japan damaged by a 2007 earthquake, in asking Dominion additional questions regarding proper examination of technical areas that included: piping systems, including buried segments; nuclear fuel assemblies; steam generators; pumps and valves; and emergency diesel generators.
The NRC’s independent actions included an Augmented Inspection Team (AIT) that examined the plant shortly after the quake, as well as a restart readiness inspection in mid-October. Both Dominion and NRC’s results showed only minor damage that did not affect North Anna’s safety systems. The NRC held public meetings near the plant on Oct. 3 regarding the AIT’s findings, and on Nov. 1 regarding the restart readiness inspection findings and the staff’s technical review. The NRC also held a public meeting at the agency’s Rockville, Md., headquarters Sept. 8 regarding Dominion’s initial assessment. On Oct. 21 the staff briefed the Commission regarding the plant’s response to the earthquake.
The NRC has issued Dominion a separate letter documenting the company’s commitment to several additional quake-related actions, including:
• Updating North Anna’s Final Safety Analysis Report to incorporate information from the quake and subsequent analysis;
• Additional characterization of the fault responsible for the Aug. 23 quake, as well as any special ground motion effects at North Anna;
• Re-evaluating plant equipment (including an assessment of potential improvements) identified in earlier seismic reviews;
• Developing any needed inspections or evaluations for components within the North Anna reactor vessels; and
• Permanently updating seismic monitoring equipment for the North Anna reactors and dry-cask spent fuel storage facility.
NRC Technical Evaluation Report Attached below (.pdf)
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LATEST UPDATE: Dominion Press Release:
Dominion Virginia Power today began the restart of North Anna Power Station after the U.S. Nuclear Regulatory Commission granted permission. More than two months of detailed inspections, testing and engineering, and seismic analysis revealed no functional damage to the station from the Aug. 23 earthquake.
Control room operators, under the oversight of both Dominion nuclear officials and NRC inspectors, initiated the restart process for Unit 1. The company first will bring Unit 1 on line safely and then begin the same process with Unit 2. It is expected to take about 10 days to return both units to 100 percent power.
The restart process for each unit normally takes about four days from cold shutdown to normal power operations in which electricity is produced and placed on the electric grid. During the restart process, hundreds of pumps, motors, valves and other systems are restarted in a carefully prescribed and observed sequence. Because the units will be starting up after the first earthquake to shut down a nuclear unit in the United States, the restart process will be prolonged to allow for additional equipment tests that can only be performed when the units are in various stages of start-up as an extra, deliberate safety precaution.
The company has increased staffing in operations, maintenance, health physics and other work disciplines on an around-the-clock shift schedule to ensure the units return to service safely and will add several additional days to the restart schedule to perform mandatory equipment tests and ensure the public's health and safety. The additional time and tests reflect Dominion's commitment to carefully monitoring systems and equipment during startup to ensure proper and safe operation following the earthquake.
Delays could occur and are not atypical even during normal startups as operators decide that additional checks or maintenance are needed.
"As always, safety is our first priority," said David A. Heacock, president and chief nuclear officer-Dominion Nuclear. "We have demonstrated to ourselves and to the NRC and are confident that North Anna is safe and ready to be restarted. The station suffered no functional damage from the quake and is ready to resume generating clean, low-cost energy safely for our customers."
The NRC recently completed its inspection of the station and independently confirmed the company's finding of no functional damage. In its Nov. 11, 2011 letter, the agency gave the company formal permission to begin the restart. As part of its restart agreement with the NRC, the company will perform a number of actions after restart to analyze and confirm North Anna's capability to withstand seismic events now and in the future.
The 1,800-megawatt twin reactors at North Anna shut down automatically and safely at 1:51 p.m. on Aug. 23 when the 5.8-magnitude earthquake occurred near Mineral, shaking Central Virginia and much of the East Coast. The epicenter was about 11 miles from the station and several miles underground.
The company immediately began a program of inspections, testing and analysis to make sure the station was undamaged and capable of being safely restarted. The program involved more than 100,000 man-hours of work and cost more than $21 million, plus the use of numerous outside seismic and engineering experts.
Dominion cooperated with the NRC throughout the process, extensively documenting all the findings and responding to all requests for additional information from the agency. The NRC held four public meetings to review and discuss the inspections and findings – two near the station and two at its headquarters in Rockville, Md.
It is about time!