Dominion restarts North Anna nuclear plant after earthquake-triggered outage
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
Mineral, Va., Nov. 11, 2011 — Dominion Virginia Power 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 Dominionnuclear 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 U.S., 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.
Delays could occur and are not atypical even during normal startups as operators decide that additional checks or maintenance are needed.
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-MW 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.