~'EACCESSION NHR

FAC IL: 50-27550-323

AUTH. NAMESHIFFERI J. D.

REC IP. NAME

REGULAT Y INFORMATION DISTR IBUT IOt, 'YBTEM (RIDB)

8803300361 DOC. DATE: 88/03/25 NOTARIZED: NO DOCKET 0Diablo Canyon Nuclear PouJer Planti Unit ii Pacific Ga 05000275Diablo Canyon Nuclear Power Planti Unit 2i Pacific Ga 05000323

AUTHOR AFFILIATIONPacif.ic Gas 8c Electric Co.

RECIPIENT AFFILIATIONDocument Control Branch (Document Control Desk)

SUBJECT: "Diablo Canyon Poeer Plant Long Term Seismic Program-Guarter lg Progress Rep t 10i Nov 1987-Jan 1988. " W/880325 1 tr.

DISTRIBUTION CODE: DOSID COPIES RECEIVED: LTR i ENCL J SIZE: /TITLE: Diablo Canyon Long-Tef m Seismic Pr ogram

NOTES:

RECIPIENTID CODE/NAME

PD5 LAROOD'

INTERNAL: ACRSNRR ABHARi HNRR JENGi DNRR REITER'NRR/DEST/ADESH3NRR/DOEA/TBB11FOQC 15-8-18RES CHOKSHII N

COPIESLTTR ENCL

1 01 1

6 61 1

1 1

1 1

1 1

1 1

1 01 1

RECIPIENTID CODE/NAME

PD5 PD

*DM/LFMBNRR BAQCHIz GNRR PICHUMANIiRNRR ROTHMANi RNRR/DEBT/ADB7E4NRR/PMAB/ILRB12

01R~ LLENI R

COPIESLTTR ENCL

5 5

01 1

1

1 1

1 1

1

1 1

1 1

EXTERNAL: LPDRNBIC

2 21 1

NRC PDR

TOTAL NUMBER OF COPIES REQUIRED: LTTR 32 ENCL 29'

0

P

p

I'

fl

Pacific Gas and Electric Company 77 Beale Street

San Francisco, CA 94106

415/973 4684TWX910 372 6587

James D. Shiffer

Vice PresidentNuclear Power Generation

March 25, 1988

PGhE Letter No. DCL-88-066

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskHashington, D.C. 20555

Re: Docket No. 50-275, OL-DPR-80Docket No. 50-323, OL-DPR-82Diablo Canyon Units 1 and 2

Long Term Seismic Program — Quarterly Progress Report No. 10(NRC RIDS Distribution Code D031)

Gentlemen:

In compliance with License Condition 2.C(7) of Facility OperatingLicense DPR-80, enclosed is the Long Term Seismic Program QuarterlyProgress Report No. 10 for work performed from November 1, 1987through January 31, 1988. Copies of the progress report are alsobeing forwarded to NRC Staff consultants and to the ACRS Staff.

Kindly acknowledge receipt of this material on the enclosed copy ofthis letter and return it in the enclosed addressed envelope.

Sincerely,

. D. Shi er

cc: E.G. Igne, ACRS (15)3. B. MartinM. M. MendoncaP. P. NarbutB. NortonH. RoodB. H. VoglerCPUCDiablo DistributionLTSP External Distribution (Attached)

Enclosure

1975S/0055K/JLP/1587

Sp325—88O33pp36'1 8 p2'PDR ADOCK 0 PDR"

R

DISTRIBUTION LIST (12)

T rm i mi Pr r m Ex r 1"

Dr. Keiiti AkiDept. of Geological SciencesUniv. of Southern CaliforniaLos Angeles, CA 90089

Hr. Don BernreuterLawrence Livermore LaboratoryP. O. Box 808Livermore, CA 94550

Dr. Dames Davi s, State Geol ogi stCA Division of Mines and Geology1416 Ninth Street, Room 1351Sacramento, CA 95814

Dr. S. T. AlgermissenU.S. Geological SurveyDenver Federal CenterP. 0. Box 25046, Hail Stop 966Denver, CO 80225

Dr. Robert D. Brown, 3r.U.S. Geological Service345 Middlefield RoadBuilding 8, ¹977Henlo Park, CA 94025

Dr. Stephen M. DayS-CubedP. 0. Box 1620La Jolla, CA 92038

Dr. Ralph 3. ArchuletaDept. of Geological SciencesUniv. of CA, Santa BarbaraSanta Barbara, CA 93016

Dr. C. J. Costantino4 Rockingham RoadSpring Valley, NY 10977

Dr. George GazetasJEC 4049Rensselaer Polytechnic Inst.Troy, NY 12180-3590

Dr. David Perkins (2)U.S. Geological SurveyDenver Federal CenterP. 0. Box 25046, Hail Stop 966Denver, CO 80225

Dr,, David B. Slemmons2995 Golden Valley RoadReno, NV 89506

Dr. Morris ReichStructural AnalysisBuilding 129Brookhaven Nati ona1Upton, NY 11973

Dr. A. S. Veletsos5211 Paisley Avenuekouston, TX 77096

Divi si on

Laboratory

Dr. Dean B. SavyLawrence Livermore LaboratoryP. 0. Box 808Mail Stop L-196Livermore, CA 94550

Dr. Robert V. WhitmanRoom 1-342Mass. Inst. of TechnologyCambridge, HA 02139

Dr. Kenneth W. CampbellU.S. Geological SurveyDenver Federal CenterP. O. Box 25046 Hail Stop 966Denver, CO 80225

Dr. R. Fitzpatrick (3) Dr. Hichel BohnBrookhaven National Laboratory 6412Bldg. 130, 32 Lewis Avenue P. 0. Box 5800Upton, NY 11973 Albuqurque, NM 87185

1975S/0055K

PG&E tte| No. DCL-88-066

ENCLOSURE

DIABLO CANYON POHER PLANT LONG TERM SEISMIC PROGRAM

QUARTERLY PROGRESS REPORT NO. 10

PACIFIC GAS AND ELECTRIC COMPANY

MARCH 1988

1975S/0055K

TABLE OF CONTENTS

SECTION

1. INTRODUCTION

2. GEOLOGY/SEISHOLOGY/GEOPHYSICS

3. GROUND HOTIONS

4. SOI L/STRUCTURE INTERACTION

5. FRAGI LI TIES

6. PROBABILISTIC RISK ASSESSHENT

1975S/0055K

~~

' Quarterly Report No. Harch ll, 1988

1. INTRODUCTION

This is the tenth quarterly progress report for the Diablo Canyon Power Plant(DCPP) Long Term Seismic Program (LTSP) . This report describes activitiesduring the period November 1, 1987 through January 31st, 1988.

During this reporting period, Phase III activities continued in all majorprogram elements: Geology/Seismology/Geophysics (G/S/G), Ground Motions,Soil/Structure Interaction (SSI), Fragi lities, and Probabi listi c RiskAssessment (PRA). The following important meetings and workshops were heldduring this period:

November 2-3, 1987

November 4-6, 1987

January 14-15, 1988

NRC/PGhE Fragility Audit Meeting, at NTS

Engineering in Long Beach, CA

NRC/PGLE SSI Workshop, in San Francisco, CA

NRC/PG&E PRA Workshop in Bethesda, HD

The following meetings and workshops are planned during the next severalmonths:

February 23-24, 1988

March 28-30

Hay 11-12, 1988

2.0 E L Y/ EI M L Y/ E PHY I

ACRS Subcommittee Heeting in San Francisco, CA

NRC plant walk down to review systems andequipment, San Luis Obispo, CA

NRC/PGhE Meeting on LTSP InterfaceRelationships - Ground Motions,Soil/Structure Interaction and Fragility,Rockville, HD

2.1 GEOLOGY

During the reporting period, additional analysis of geomorphic and geologicdata was conducted to further define and characterize the San Luis-Pismostructural block and bordering fault systems. Differences in topographicexpression and uplift rates suggest that the San Luis-Pismo block consists ofthree distinct segments or subblocks. These segments are termed the IrishHills, Edna, and Newsom Ridge subblocks. Recognition of these subblocks hascontributed to our understanding and interpretation of segmentation on thebordering fault systems, the Los Osos fault zone to the northeast and thesouthwestern boundary zone to the southwest. Differences in topographicexpression of the San Luis-Pismo block provide physical criteria for faultsegmentation, such as range-front versus intra-range characteristics andheight of the range-front escarpment. Differences in uplift rates of thesubblocks implies corresponding differences in behavioral characteristics onthe bordering faults, such as slip rate and recency of activity. These

1975S/0055K

'uarterly Report No. Harch ll, 1988

physical and behavioral characteristics of the San Luis-Pismo block andbordering fault systems are currently being quantified.

Further analysis of borehole and geophysical data was conducted to assess thestyle and rates of deformation of structural elements along the southwesternblock margin. These structural elements include the San Luis Bay, Wi lmarAvenue, Pecho and Oceano faults, the Black Lake Canyon monocline, and the LosBerros structural feature. Each of these structures producesdown-to-the-southwest displacement or deformation. As reported earlier, theSan Luis Bay and Wi lmar Avenue faults show minor di splacements of latePleistocene (post 120,000-year-old) deposits and geomorphi c surfaces. TheOceano fault and Black Lake Canyon monocline clearly deform late Tertiarystrata. Stratigraphic and geomorphic relations suggest Quarternaryactivity. Recency of activity, however, is not well constrained at this timeand further analysis is in progress.

2.2 OFFSHORE GEOPHYSICAL INVESTIGATION

Analyses of both the high-resolution and common-depth point (CDP) seismicreflection data were continued with emphasis on the Hosgri fault zone andassociated structures in the reach between Piedras Blancas and Point Sal.The geophysical images of the offshore San Simeon fault, the "step over"structures between the San Simeon and Mosgri faults, and the offshoreextensions of the northwest trending structures associated with the SanLuis-Pismo structural block were documented and characterized as to thespecific nature of the structure and evidence for recency of movement,

A preliminary interpretation of the deep seismic reflection lines wascompleted and presented at the American Geophysical Union meeting in SanFrancisco, in December. These data, collected for PG&E in 1986 by Digicon,were integrated with gravity and magnetic data and offshore well records toshow sediment-basement contacts for the offshore basins as well as deepcrustal reflections that may be indicating ancient oceanic crust.

The Queenie structure, an offshore fold in the central Santa Maria Basin, wasanalyzed by means of constructing retrodeformable sections. The use of thisanalysis technique allowed limits to be placed on the style and rate ofdeformation.

Additional high-resolution and deep reflection data were obtained from theoffshore areas between Point Arguello and Point Sal. These are relatively newdata sets recently acquired from the California State Lands Commission and thedata will be integrated into the continuing interpretation of the area southof Point Sal during the second quarter of 1988.

2.2.1 i h-R 1 i n i mi

The major effort in the high-resolution geophysics program during thisreporting period was in developing interpretative data compilations:

o Working map of offshore San Simeon fault between Ragged Point and PfeifferPoint based on interpretation of available geophysical records (BBN, USGS

1975S/0055K

'uarterly Report No. - 3- March ll, 1988

Bartlett, USGS Lee, CGI, Hestern, Comap), and plotted on an existing1:125,000 scale track chart base.

o Horking detailed bathymetric map of the Lompoc and Purisima/Triciastructures at a scale of 1:24,000.

o An annotated bibliography including draft summaries of pertinentreferences based upon a review of literature covering the late Miocene tocurrent pattern of tectonism in the region of the Hosgri fault, theonshore and offshore Santa Maria Basin, and the western Transverse Ranges,as indicated by seismicity, geodetic data and interpretations, strainpatterns, faults,. folds, down-warps, uplift, plate tectonic vectors and

timing, and other relevant factors.

o Horking detailed bathymetric map (scale 1:24,000, contour interval 2 m) ofthe seafloor off DCPP. Geomorphic anomali es were classified into one ormore of the following categories: shoreline angle of a former sea levelstill stand, current scoured surface, erosion-resistant bedding, faultscarp, fault-line scarp, or slump scarp. Recency of faulting and rates ofslip within the last 20,000 years were estimated from observed offsets ofthe late Hisconsinian unconformity and overlying sediments.

o Horking index maps, 1:24,000 scale track chart maps, a line by linetabulation of each geophysical survey's imaging systems (CDP, boomer,sparker, echo sounder, side scan sonar, 3.5 kHz, 1 kHz), and numerousillustrations of both interpreted and uninterpreted seismic sections offaults adjacent to the Hosgri-San Simeon trend from Lopez Point on thenorth to the vicinity of Point Sal.

2.2.2 Tw Fiv n i mi i

Eleven working seismic sections covering the southern end of the Hosgri faultand the Lompoc structure were completed in preliminary draft form. Annotatedcopies of GSI 80 migrated lines 106, 107 and 107A, 108A, 1128 and 112C, 113

and 113A, 114, 115, 116, 117, 118 and 119 were prepared for internal review,The draft geologic section 1" 2000'rawn along line GSI 80 -114 through theGetty P-0424-1, ARCO P-0425-1 and P-0425-2 wells was completed. Draftsections of GSI 80 Lines 96, 95, 94A, and 93 were completed at 1" -

2000'cale.

2.3 CENTRAL COAST SEISMIC NETHORK

Seismic activity totalling 22 earthquakes was scattered within the southcentral coastal area during the three-month interval. The largest event, withmagnitude 3.0 (U.S.Geological Survey (USGS)), occurred in November onshoreabout 20km northeast of San Simeon Point along the Nacimiento fault zone.

The closest earthquake activity to the plant site was a small sequence of fourevents that occurred in December during a three-hour period. The largestevent of the sequence was of magnitude 2.4 (USGS) and was centered in thesouthwest portion of Estero Bay about 10km northwest of the Diablo Canyon site.

1975S/0055K

'uarterly Report No. March ll, 1988

The Central Coast Seismic Network also recorded the two strong earthquakes(magnitudes 6.0 and 6.3 (USGS)) on November 24 in the Imperial Valley.

Despite the severe winter coastal weather conditions during the month ofDecember, the Central Coast Seismic Network continued to perform well.Calibrations of three component stations were completed and solutions forcases of high noise levels were determined and implemented.

3. R ND H N

3.1 EHPIRICAL GROUND MOTION STUDIES

Hork continues on the documentation of the strong motion data base compiledfor the LTSP. Other activities included review of NRC consultants'uestionsrelated to empirical studies and participation in the NRC/PGhE Horkshop on SSIheld in the first week of November. A set of 12 processed ground-responsestrong motion records from the October 1, 1987, Hhi ttier, Californiaearthquake, was acquired as part of the continuing effort to update the strongmotion data base.

3. 2 NUHERICAL MODELING PROGRAM

Recordings of two local earthquakes at USGS seismic stations PSE, TPR, and TTB

were analyzed to assess whether the site response at station PSE isrepresentative of the region around the DCPP site. Preliminary resultsindicate that station PSE has anomalously large response centered at 6 Hz, inagreement with the results of Phillips and Aki . Stations TTB and TPR do notshow such anomalous response. It therefore appears that the response ofstation PSE is not characteristic of the site region.

The existence of distance saturation in the ground motion attenuationrelationships was studied by constructing profiles of ground motionsimulations crossing the fault through the center of the asperity, both forthe 1979 Imperial Valley earthquake and for DCPP site simulations. Theresults indicate that the attenuation of peak acceleration across this profileis not linear but flattens toward the fault. The preli nimary conclusion isthat this supports the use of empirical attenuation relationships that containdistance saturation.

Additional tests of the ground motion simulation procedure developed for theLTSP were performed against strong motion recordings of the 1987 HhittierNarrows, the 1985 Nahanni, and the 1983 Coalinga earthquakes, using relatively

. sparse information available for constraining, the source models. In the caseof the Hhittier Narrows earthquake, very good agreement between observed andsimulated motions was obtained in peak acceleration and velocity, wave form

,character and duration of the time histories, the amplitude and shape ofresponse spectra, and the attenuation of peak acceleration and velocity withdistance from the source. The simulations reproduced the observed featuresaccurately enough to allow identification of phases and amplitudes that may be

attributable to local site effects. 'For example, the Nhittier-Bright AvenueStation has the largest simulated peak acceleration, in agreement with therecorded peak acceleration data.

1975S/0055K

1

'uarterly Report No. March ll, 1988

In the case of the Nahanni earthquake, simulations were made for the threeclosest stations. Again, reasonable agreement was obtained with the exceptionof the large phase appearing late in the record at Station 1. The origin ofthis phase is not clean. It could have originated from secondary faultingvery close to Station l. Simulations for this earthquake using the 1979Imperial Valley aftershock recordings as the empirical source functions areslightly defi ci ent at high frequencies. In the case of the Coalingaearthquake, simulation for one free-field station, the Pleasant Valley Pump

Station, was made using the westward dipping shallow-angle fault plane. Good

agreement both in time history and response spectrum was obtained.

Results of these tests indicate that our numerical modeling procedure withvery few exceptions can provide reliable simulations even for cases for whichonly sparse source information is available.

The adequacy of the generalized ray method for computing Green's functions forshallow sources was assessed by comparing the Green's functions for a sourcedepth of 1.25 km using the generalized ray method with those using thewavenumber integration method. The latter gave complete representations ofthe wave field in a.plane layered crustal structure. The results indicatethat the Green's functions using the wavenumber integration method containseveral contributions that are not generated using the generalized raymethod. These include surface waves and near-surface reflections. Thesignificance of these results is being assessed.

3.3 ASSESSMENT OF SPATIAL INCOHERENCE

Possible variation of spatial incoherence of ground motion over different timewindows of the records, (i.e. the non-stationarity) was assessed by analyzingthe El Centro differential array data of the 1979 Imperial Valley earthquakeusing a narrow moving window. The variation of spatial incoherence withwindow length was also examined. The results indicate that the peak spatialcoherence tends to be higher during the peak motion, in agreement with theresults of Spudich and Cranswick.

It is also found that the estimate of spatial incoherence changes onlyslightly with window length. For the purpose of providing a realisticcharacterization of spatial incoherence for use in the SSI analyses, a windowlength was selected which corresponds to the strong motion duration on theorder of 10 seconds for a magnitude 7 earthquake at close range. By so doing,the estimates of spatial incoherence should not be significantly affected bythe lower coherence of the coda waves.

3.4 STRONG MOTION INSTRUMENTATION

No earthquake was recorded by the strong motion instruments at DCPP duringthis reporting period.

A solid state recording unit was installed in January as part of the DCPP

Supplementary Seismic Monitoring System. It records the output from one ofthe free-field accelerometers. The unit is connected through a modem to a

dedicated telephone line so that it can be routinely interrogated about its

1975S/0055K

t

'Quarterly Report No. March ll, 1988

recording status using a personal computer at remote locations. This new

addition enables us to access and retrieve the recorded data more quickly.

4. L/ R RA TI

4.1 INPUT TO FRAGILITY EVALUATION

Plant responses to median site-specific ground spectra for modified Tabas and

Pacoima records were provided to the fragility group. These includedresponses for the coherent ground motion and modification of these responsesfor ground motion incoherency characteristics. The effect of potential upliftof containment was also provided as a modification factor to the coherentground motion containment response.

4.2 NRC/PGLE HORKSHOP

A preliminary interim report was developed and sent out in advance to theparticipants for the NRC/PGhE SSI workshop held on November 4-6, 1987. The

report contained detailed discussions of procedure, methodology, and selectedresults of issues such as SSI analysis with coherent ground motion,containment uplift, and SSI analysis for spatial incoherency ground motioncharacteristics. In addition to discussions on the above SSI topics, theworkshop also included detailed discussions on various ground motion studiesand their engineering uses.

5. EMIUIJiS5.1 NRC/PG8(E HORKSHOP

The NRC/PGhE Fragility Horkshop held on November 2 and 3, 1987, includeddetailed discussions with the NRC Staff and their consultants of theprocedures and methodology that are being followed in the LTSP fragilityevaluation. A set of additional information was requested by the NRC Staffand consultants to help them in preparation of actual review of PG&E's

fragi 1 i ty work.

5.2 PHASE IIIB ACTIVITIES

Hork continued on developing Phase IIIB fragilities of essential plantstructures and components. The effort includes, for the first time in thephased fragility work, incorporation of plant responses to site-specificmedian ground motion and the variabilities associated with the medianresponses. The effects of ground motion incoherency characteristics andcontainment uplift are also being appropriately accounted for. Evaluationsare also being performed, as appropriate, to upgrade capacities of some

equipment and components.

6. A L TI I K MENT

Hork continues on Phase IIIB of the PRA. The Human Actions review by theoperations department at DCPP has been completed. Their comments andevaluations are being incorporated into the PRA model. Frontline Systems

1975S/0055K

C'

Quarterly Report No. Harch ll, 1988

Analysis and Top Events were sent to the NRC Staff and consultants for reviewand comments. A workshop was held in Bethesda, Maryland on January 14 and 15,1988. Phase IIIA interim results were presented along with variousmethodologies used in the PRA Analysis.

1975S/0055K

, I

v

l