UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555-0001
October
12,
2012
Mr. Edward
D.
Halpin
Senior Vice President and
Chief Nuclear Officer
Pacific Gas and Electric Company
Diablo Canyon Power Plant
P.O. Box
56,
Mail Code
104/6
Avila Beach, CA 93424
SUBJECT: DIABLO CANYON POWER PLANT, UNIT NOS. 1 AND 2 - NRC REVIEW OF
SHORELINE FAULT (TAC NOS. ME5306 AND ME5307)
Dear Mr. Halpin:
On January
7,2011,
Pacific Gas and Electric (PG&E, the licensee) provided the U.S. Nuclear
Regulatory Commission (NRC) with a report on the analysis of the Shoreline fault. This report
can be found in Agencywide Documents Access and Management System (ADAMS) Accession
No. ML 110140431. This report provided new geological, geophysical, and seismological data to
assess the potential seismic hazard of the Shoreline fault.
Based
on
our review, the NRC has confirmed our preliminary conclusion that the Diablo Canyon
Power Plant's (DCPP's) ground motions from the Shoreline fault are at or below those for which
the plant was evaluated previously and demonstrated to have reasonable assurance of safety.
This letter provides a summary of the results of the NRC's independent assessment of the
information found
in
the January
7,
2011, report. The staff's more complete assessment
is
documented in Research Information Letter (RIL) 12-01 "Confirmatory Analysis of Seismic
Hazard at the Diablo Canyon Power Plant from the Shoreline Fault Zone" (ADAMS Accession
No. ML 121230035).
In
addition, this letter places the NRC's review of the Shoreline fault into
context with a recent NRC action to have all of its nuclear power reactor licensees conduct
seismic reevaluations. This action is documented
in
the March 12, 2012, request for information
that was sent pursuant to Title 10
of
the
Code
of
Federal
Regulations
(10 CFR), Section 50.54(f)
(ADAMS Accession No. ML 12053A340).
Shoreline Fault Report
On November 14, 2008, PG&E informed the NRC that it had identified a zone
of
seismicity that
may indicate a previously unknown fault located offshore of the DCPP. The potential fault was
identified as a result of a collaborative research program between PG&E and the U.S.
Geological Survey (USGS). This research program, called the PG&E-USGS Cooperative
Research and Development Agreement (CRADA), focuses
on
increasing the understanding of
tectonics
in
the region around the DCPP.
Shortly after PG&E reported the potential for a new fault, the licensee's representatives
provided the NRC with sets of initial scientific data and information related to the hypotheSized
fault in e-mails dated November 20 and
21,2008
(ADAMS Accession Nos. ML090690193 and