ML20153B041

Comments on ACRS Subcommittee on Diablo Canyon Meeting on 880223-24 in Burlingham,Ca Re Status of Long Term Seismic Program of Plant

ML20153B041
Person / Time
Site:	Diablo Canyon
Issue date:	03/31/1988
From:	Scavuzzo R SCAVUZZO, R.J.
To:
Shared Package
ML20153A989	List: ML20153A984 ML20153B041
References
ACRS-CT-1928, NUDOCS 8807120695
Download: ML20153B041 (3)

Text

. - _ _ _ _ - _ - _ _ - _ _ - _ - _ _ - _ _ _ _ _ __

_ - - _ - - _ - _ _ _ _ _ _ _ _ - - _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ - _ - _ _ _ - _ _ _ _ _ _ _ _...._._s....__.

~e

., s , ,

d

g. . ,

0.

is' .

ACRS Subcommittee on Diablo Canyon D '.< ;' -

February 23-49, 1988 Bur 11ngam, California l r

! R. J. Scavuzzo, Phd, PE l

Consultant to the ACRS l

l l

l f1 arch 31, 1988 9

l

\

\

8807120695 880419

\ PDR ACRS i CT-1928 PDR l

1

~,.,.-..,,,,..,,-,,,.,,._.,,.__,,,_n_., --_.n..-.--,,. ._ , . . , . , , , , - - _ . . . . . - . ,

. v 8

f?

'SEk

lt INTRODUCTION The objective of the meeting was to review the status of the long term seismic program of the Diablo Canyon Nuclear Power Plant. After an introduction, the technical topics covered included Regional Geology, Seismology, Geophysics, Earthquake Ground Motions, Soil / Structure Interaction, Fragilities, and Probabilistic Risk Assessment. My own expertice, exists is in the areas of Earthquake Engineering which includes Ground Motions, Soil / Structure Interaction and Structural Analysis which includes some aspects of Fragilities. Comments are presented on the overall presentation, geological-seismological geophysical studies as they affect ground motions, response spectra and fragilibility.

DISCUSSION GEOLOGY / SEISMOLOGY / GEOPHYSICS PROGRAM The program in this area is being conducted in a very through and professional manner. The entire Santa Maria Basin Region which includes both offshore and coastal land areas have been thourghly studied using available literature, borehole / water well investigations, trenching investigations, and reflection / refraction surveys. Recent (1980-84) as well as historic seismicity of the region has also been throughly studied. These data nave been used in establishing the magnitude and frequency content of the earthquake ground motion.

Based on the presentations, the impression is obtained that more effort in terms of funding and man hours have been spent in this area than other aspects of the seismic reevaluation program. Since the seismic ground motions and response spectra have been established, it is recommended that the major effort of the reevaluation be spent on the structural analyses of equipment, hold-down bolts, systems and buildings while still maintaining a strong program on these geological aspects of the region. In my opinion, at this time, the most relevant engineering effort will be the -

dynamic structural reevaluation of the plant and equipment.

- - - _ - _ _ _ - _ _ _ - - _ _ _ _ _ _ _ - _ _ _-_ _ _ _ _ _ _ _ _ _ _ _ _ {

-c l l k ']l:

2. :4

.? A Y-s ji GROUNG MOTION The level of the zero period lateral ground spectrum acceleration is approximately c.6g. Thir, value was obtained from yhe LTSP Median Site-Specific Hor 11zontal Spectrum presented by PG&E engineers. Measurements at the Pacoima Dam rock outcroping produced peak accelerations of 1.25g (1).

Based on the fact that there was amplification at the Pacoima dam site, this level seems acceptable even though prudence might indicate a higher value.

The dominant frequency of the Pocolma Dam site was approximately 3 to S Hz (1). Thus, the frequency content of the proposed spectrum appears to be satisfactory.

FRAGILITY STUDIES There is a significant effort being made on the fragility evaluation of the Diablo Canyon Power Plant. Much of the effort appears to be associated with probablistic evaluation of spectra and probablistic risk assessment. In addition to continuing this work, it is recommended that the most critical equipment, systems and structures be determined by through dynamic analyses and that margins of safety be established. Emphasis should be placed on the deterministic and probablistic evaluation on these critical components, systems, hold down bolts or structures.

REFERENCES (1) Murphy, L. M., "San Fernando, California, Earthquake of February 9,1971, Volume III", U. S. Department of Commerence, 1973, pp 375-391.

~

I I

L .

m....- --- -- - - .