October 21, 2011 / 10:01 PM / 6 years ago

UPDATE 1-US NRC examines North Anna nuclear plant after quake

* North Anna reactors shut after earthquake in August
    * NRC must grant permission before North Anna returns
    * NRC says inspections of plant are ongoing

    By Scott Disavino and Ayesha Rascoe
    Oct 21 (Reuters) - Virginia-based power company Dominion said on Friday it was ready to restart the 1,806-megawatt
North Anna nuclear power plant, but federal nuclear regulators
said their safety review of the plant had yet to end.
    The plant shut down automatically on Aug. 23 when an
earthquake struck central Virginia. The epicenter was about 11
miles (17.5 km) from the station and about four miles
underground.
    The quake marked the first time an operating U.S. nuclear
plant experienced a tremor that exceeded its design
parameters.
    The U.S. Nuclear Regulatory Commission (NRC) on Friday
reiterated its commitment to ensuring that the plant is totally
safe before it allows operations to resume.
    "The bottom line is that the NRC will not authorize restart
until we are satisfied that the plant can be operated while
protecting public health and safety," Bill Borchardt, NRC
executive director of operations, said at a commission
hearing.
    The restart process for North Anna has taken place in the
shadow of the nuclear disaster that roiled Japan in March when
an earthquake and tsunami damaged the Fukushima Daiichi nuclear
power plant, causing reactor fuel meltdowns and radiation
releases.
    'DESIGN BASIS ISSUE'
    Dominion said both North Anna units are ready to restart
once the agency completes its independent review, analysis, and
on-site inspections and grants permission.
    "The lack of damage from the Aug. 23 earthquake clearly
demonstrated that North Anna's true seismic capability is
greater than design basis of the station," David Heacock,
president and chief nuclear officer of Dominion, said in a
release.
    "While the quake lasted about 25 seconds, only 3.1 seconds
of intense motion occurred. The station could have withstood
significantly more," Heacock said.
    The NRC also said so far it had found no significant damage
at the plant.
    However, some commissioners at the nuclear regulator
questioned the possible implications of this event for the
agency's regulatory regime.
    "We have a design basis issue ... if we know the design
basis has been exceeded, how do you continue to operate unless
you make that change in design basis?" NRC commissioner William
Magwood said at the meeting.
    At the NRC's request, Dominion said it agreed to perform
additional seismic analysis on certain components after restart
to quantify and further demonstrate they can meet specific
seismic requirements.
    Dominion said it spent about $21 million on its inspection,
testing and analysis program, including repairs, since the
earthquake occurred.
    Dominion has said the 903-MW North Anna Unit 1 has been
ready to return to service since the end of September. Dominion
conducted a planned refueling on the 903-MW North Anna Unit 2
during its downtime.

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