ML20215N063
| ML20215N063 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Diablo Canyon |
| Issue date: | 04/16/1976 |
| From: | Sihweil I Office of Nuclear Reactor Regulation |
| To: | Heineman R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20197J003 | List: |
| References | |
| FOIA-86-371 NUDOCS 8611040232 | |
| Download: ML20215N063 (4) | |
Text
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R. E. Heinecan, Director, Division of Systems Safety, NRR THRU:
R. R. Maccary, Assistant Direct 6r for Engineering, Division of Systems Safety, ?!RR HEETING BEWEEN SED STAFF AND N. M. NEW1 ARK CONSULTING ENGINEERI?iG SERVICES CONCERNING DIABLO CANYON, APRIL 12, 1976
Reference:
'" Seismic !! ave Effects On Soil Structure Interaction" by R. II. Scanlan, 3rd SMIRT Conference,1975.
The SEB met with M. M. Hewiark Consulting Engineering Services at the Dulles Airport Holiday Inn to discuss seismic design requirements for the Diablo Canyon Nuclear Power Plant on April 12, 1976. Representatives from the Division of Project Management and the Office of Executive Legal Director attended.
A list of attendees is attached.
- M 86 Professor Newmark made a presentation on his proposal for the seisnic analysis of the Diablo Canyon site which treated modifications and reductions of design response spectra and considerations relating to tilting and torsion.
At the request of the SEU, ductility ratios were also discussed. After several exchanges of views the following con-clusions were agreed upon:
1.
The applicant will be asked to specify a magnitude 7.5 earthquake at the HOSGRI fault with horizontal spectra normalized to 0.75.
9 Regulatory Guide 1.60 spectral shapes may be used. Use of the HOSGPI spectral shape will require further justification since it is believed that the liOSGRI spectral shape was developed for lower magnitude carth-quakes.
2.2.
A reduction in both horizontal and vertical response spectra will be permitted depending on the actual equivalent length of individual buildings. This reduction recognizes that ground motions are not synchronized under structures during earthouakes.
In other words, different points in the foundation base slab will not experience the maximum free field ground motion at the same time. The qquiv-alent length of each individual structure will be equal to the square root of the building base slab area. The magnitude of the reduction factor shall be determined as the average of the value from the theoretical procedure given by Scanlan (see Reference) for a hannonic wave and the value determined using the Pacoima Dam record obtained in the 1971 San Fernando earthquake. The harmonic 861104023 861023 erree
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R. E. lieineman 6 1976 wave in the Scanlan procedure will be assumed to have a frequency of 7 hertz.
3.
Where such reduction in response spectra is used, the applicant will be asked to appropriately account for additional tilting and torsion which may result from the nonsynchronized earth-quake motions considered in item 2 above.
4.
In reevaluating the capability of the plant structure, systems and components, inelastic behavior may be relied upon to absorb the ground motion energy. Where such a behavior is relied upon, a ductility ratio not e ceeding 1.2 may be used in determining x
seismic loads and motions. For each particular structure where this ductility is relied upon, the applicant will be asked to provide justification and bases for assuring that the increased strains and deformations will not affect the safety functions of the plant systems and structures. This ductility ratio is permitted by the SEB staff for near-field earthquake;have WiNllll84 such as those associated with the HOSGRI fault,which tend to shorter durations of strong motion.
It is recognized that for short duration earthquakes, the use of elastic response spectra tends to produce overly conservative results.
5.
It was also decided that the analytical work required to develop individual response spectra for the various plant buildings will be perforned by the applicant and a report will be requested thereafter. The SEB staff and Dr. Newnakk will review this report and only thereafter will finalize the SER for release.
. The above procedure is a departure from current y imposed requiremeets.
l Items 2 and 3 taken together are felt to be an optional and acceptable description of the seismic event which could lead to reduced seismic loads in some elements and increased loads elsewhere, Item 4 is a relaxation of criteria which will produce a reduced,. ret acceptable, margin of safety. A technical base exists for pennitting the reduced safety margin as indicated in iten 4 Isa S. Sibweil, Chief Distribution:
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i LIST OF ATTENDEES
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MEETING BETWEEN SEB STAFF AND N. M. NEWMARK CONSULTING ENGINEERING SERVICES CONCERNING DIABLO CANYON, APRIL 12, 1976.
N. M. Newnark N. M. Newnark Consulting Engineering Services W. J. Hall N. M. Newnark Consulting Engineering Services D. P. Allison NRC/DPM
- 0. D. Parr NRC/DPM
' L. D. Davis NRC/0ffice of Executive Legal Director M. J. Grossman NRC/0ffice of Executive Legal Director I. Sihweil NRC/ DSS D. Jeng NRC/ DSS K. Kapur NRC/ DSS F. Schauer NRC/ DSS P. Kuo
.NRC/ DSS.
J. O'Brien NRC/ DSS
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