ML110910132

Licensee Handouts from 3/31/11 Meeting with Pacific Gas and Electric Station Seismic Update

ML110910132
Person / Time
Site:	Diablo Canyon
Issue date:	03/31/2011
From:	Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation
Polickoski J, NRR/DORL/LPL4, 415-5430
Shared Package
ML110910125	List: ML110910132 ML110910146 ML110910157
References
TAC ME5033, TAC ME5034
Download: ML110910132 (3)

Text

DCPP Long Term Seismic Program Update Evaluation of Updated Seismic Hazard Information DRAFT (03-29-2011)

Flowchart A - Overview Process for Updates to the Long Term Seismic Program (LTSP)

Seismic Probabilistic Risk and Seismic Margins Assessment (to be performed on a 10 year interval) (1)

T Updated LTSP Seismic Hazard Input Information Received by DCPP (2) or Ten Years Since Prior Update (1)

Seismic Probabilistic Risk Assessment Confirmatory Path AF Used for Safety Risk Assessment (cannot start until seismic hazard curves are available and typically, the assessment will take 6 months to complete)

See (4)

Seismic Margins Assessment Primary Path Used for Operability Determination (to be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of receipt of data)

See (3)

DR Flowchart Submit Peer-Reviewed Flowchart C Updated LTSP Information to B Nuclear Regulatory Commission (NRC) /

Nuclear Reactor Regulation (NRR)

Restart 10 Year Interval Notes:

(1) Update to be performed at less than a 10 year interval if significant new information becomes available. The start of each interval to be based on submittal date of prior update.

(2) Seismic Hazard Input is developed by the PG&E Geosciences Department. Types of input include seismic hazard curves, deterministic ground motion response spectrum, source characterization, ground motion spectral shapes, etc.

(3) Seismic Margins Assessment based on deterministic ground motion response spectrum.

(4) Seismic Hazard Curves are typically available within 30 days.

DCPP Long Term Seismic Program Update Evaluation of Updated Seismic Hazard Information DRAFT (03-29-2011)

Flowchart B - Seismic Margins Assessment Entry Point from Flowchart A Updated Seismic Hazard Information for Seismic Margins Assessment (SMA) Received by DCPP or 10 Year Update (1)

T

- Updated Deterministic Ground Motion Response Spectrum (DGMRS)

Is Updated DGMRS Enveloped by 1991 LTSP DGMRS(4)

?

Yes AF No Do Changes to DGMRS Update HCLPF Capacities for Require Updated High Confidence Impacted Structures, Systems, Yes Low Probability of Failure (HCLPF) and Components (SSCs) (3)

Capacities (2)

?

No Update HCLPF Capacities for Impacted Reassess Plant Seismic Margins for Impacted Structures, Structures, Systems, Systems, and Components (SSCs) with Updated DGMRS, and Components HCLPF Capacities (SSCs) (3),

if required Is Enter Tech. Spec. Limiting Min. Seismic Condition for Operation No Margin > 1.0 DR (LCO) for Impacted SSC(s)

(SSC(s) Inoperable)  ?

Yes Develop Modifications to Submit License Amendment Request Restore Seismic Margins to Update 1991 LTSP DGMRS (5) and/or 1977 Hosgri Response Spectrum (RS) (6)

Document Updated LTSP DGMRS (7),

Return to Hosgri RS(7), HCLPF Capacities, Flowchart A Seismic Margins in DCPP Records Notes:

(1) The Deterministic Ground Motion Response Spectrum (DGMRS) is developed by the PG&E Geosciences Department in accordance with peer- reviewed methodologies.

(2) Changes in the DGMRS may impact the in-structure response spectra, which are an input to the High Confidence Low Probability of Failure (HCLPF) capacities of Structures, Systems, and Components (SSCs).

(3) The HCLPF capacities are based on the methodologies defined in EPRI NP-6041-SL.

(4) The 1991 LTSP DGMRS is that defined in the 1988 LTSP Final Report, as modified by the NRC in SSER-34 (1991).

(5) Update required if the Updated DGMRS exceeds the 1991 LTSP DGRMS at any frequency.

(6) Update required if the Updated DGMRS exceeds the design basis 1977 Hosgri Earthquake response spectrum, as defined in in the DCPP Updated Final Safety Analysis Report, Section 2.5, at any frequency (7) The 1991 LTSP DGMRS and/or the 1977 Hosgri RS may be updated based new information subsequent to NRC approval of a License Amendment.

DCPP Long Term Seismic Program Update DRAFT Evaluation of Updated Seismic Hazard Information (03-29-2011)

Flowchart C - Seismic Probabilistic Risk Assessment Entry Point from Flowchart A T

Updated Seismic Hazard Information for Seismic Probabilistic Risk Assessment (SPRA)

Received by DCPP or 10 Year Update

- Updated Seismic Hazard Curve (SHC)

- Updated Ground Motion Spectral Shape (GMSS)

(1)

(1)

AF Conduct SPRA to Determine Seismic Core Damage Frequency (SCDF)

With

- Updated Input Information

- Updated Methodologies Notify Nuclear (3)

(2), (4)

DR Regulatory Commission (NRC)

Document Updated SHC, GMSS, Fragilities, and SCDF in DCPP Records Return to Flowchart A Notes:

(1) The Seismic Hazard Curves (SHC) and Ground Motion Spectral Shape (GMSS) are developed by the PG&E Geosciences Department in accordance with peer- reviewed methodologies.

(2) The Seismic Probabilistic Risk Assessment (SPRA) will be based on Capability Category II of ASME/ANS RA-Sa-2009, as modified by Reg. Guide 1.200.

(3) Input information includes seismic hazard curves, ground motion spectral shape, and fragilities.

(4) Fragilities are based on the shape of the ground motion spectral shape and peer-reviewed fragility calculation methods (ASME/ANS RA-Sa-2009, as modified by Reg. Guide 1.200, EPRI TR-103958, 1002988, 1019200)