ML13317B070
| ML13317B070 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/05/1982 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Dietch R Southern California Edison Co |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR LSO5-82-04-013, LSO5-82-4-13, NUDOCS 8204070482 | |
| Download: ML13317B070 (6) | |
Text
April 5, 1982 Docket No. 50-206 LS05-82 013 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770 01
Dear Mr. Dietch:
SUBJECT:
FREE FIELD MOTION TO BE USED IN THE SEISMIC REEVALUAT OF SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 REQUEST FOR ADDITIONAL INFORMATION As a result of the February 16, 1982 meeting and the subsequent discussions bctween the NRC staff and your representatives and consultants, the NRC has found that the Housner Spectra anchored at 0.67g, which you have been using as the basis for your seismic reanalysis program, are in general appropriate except for small exceedances (up to 10%) in specified-period ranges. Specifically, the staff's best estimates of the 84th percentile spectra from the controlling.earth quake would exceed the horizontal Housner Spectra by up to 10% in the period range from 0.07 second to 0.25 second and the vertical Housner Spectra by up to 10% in the period range from 0.05 second to 0.15 second.
Subject to the receipt of the confirmatory information as described in Enclosure I, which you have committed to provide, it is the NRC's position that the 0.67g Housner Spectra are the free field motion appropriate for the reanalysis of structures, systems and components for seismic upgrading of the San Onofre Nuclear Generating Station, Unit 1. You should provide this confirmatory infor-St0' mation by April 16, 1982. The staff plans, to issue a safety evaluation documenting
/
staff's bases for this position by May 31, 1982.
In order to conclude ;that the seismic safety margin-in structures, systems and components are adequate considering the 10 percent exceedances of the Housner Spectra over the specified period, you zAn t
should provide.responses to the questions in Enclosure II.
Your response is. 40t requested within 45 days of receipt of this letter.
The,reporting and/oryrecordkeeping requirements contained in this letter affectTLS o4 fewer than ten respondents; therefore, OMB clearance is not required under L.,je P.L.96-511.
- SEE PREVIOUS PAGE FOR CONCURRENCES
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NRC FORM 318 (10-80) NRCM 0240 OFF IC IA L RECORD COPY USGPO: 1981--335-960
DESIGNATD ORIGINAL Certified By
. I t Docket No. 50-206 LS05-82 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770
Dear Mr. Dietch:
SUBJECT:
FREE-FIELD MOTION TO BE USED IN THE SEISMIC REEVALUATION OF SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 REQUEST FOR ADDITIONAL INFORMATION As a result of the February 16, 1982 meeting and the subsequent discussions between the NRC staff and your representatives and consultants, the NRC has found that the Housner Spectra anchored at 0.67g, which you have been using as the basis for your seismic reanalysis program, are in general appropriate except for small ex eedances (up to 10%) in specified period ranges. Specifically, the staff's best estimates of the 84th percentile spectra from the controlling earthquake would exceed the horizontal Housner Spectra by up to 10% in the period range from 0.07 second to 0.25 second and the vertical Housner Spectra by up to 10% in the period range from 0.05 second to 0.15 second.
Subject to the receipt of the confirmatory information as described in Enclosure I, which you have committed to provide, it is the NRC's position that the 0.67g Housner Spectra are th' free field motion appropriate for the reanalysis of structures, systems and components for seismic upgrading of the San Onofre Nuclear Generating Station, Unit 1. 'You should provide this confirmatory information by April 16, 1982. The staff plans to issue a safety evaluation documenting staff's bases for this position by May 31, 1982. In order to conclude that the seismic safety margin in structures, systems and components are adequate considering the 10 percent exceedances of the Housner Spectra over specified periods, you should provide responses to the questions in Enclosure II. Your response is requested within 45 days of receipt of this letter.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than tendrespondents; therefore, OMB clearance is not required under P.L.96-511.
Sincerely, OR4M 0
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NRC FORM 318 (10-80)
OF CIAL RECORD COPY USGPO:1981-335-960 W nclosures:
See nex age
Mr. R. Dietch cc Charles R. Kocher, Assistant General Counsel James Beoletto, Esquire Southern California Edison Company Post Office Box 800 Rosemead, California 91770 David.R. Pigott Orrick, Herrington & Sutcliffe 600 Montgomery Street San Francisco, California 9411-1 Harry B. Stoehr San Diego Gas & Electric Company P. 0. Box 1831 San Diego, California 92112 Resident Inspector/San Onofre NPS c/o U. S. NRC P. 0. Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of.Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN:
Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California' 95814 U. S. Environmental Protection Agency Region IX Office ATTN:
Regional Radiation Representative 215 Freemont Street San Francisco, California. 94111 Robert H. Engelken, Regional Administrator Nuclear Regulatory Commission, Region V 1450 Maria Lane Walnut Creek, California 94596
ENCLOSURE I Recommendation for Free Field Motion to be Used in the Seismic Reevaluation of SONGS I
- 1. The Geosciences Branch has reached a decision with respect to the free field ground motion to be used in the reevaluation of San Onofre Nuclear Generating Station Unit 1 (SONGS 1).
It is based upon review of the following items:
- a.
The SONGS 2 & 3 SER.(NUREG-0712) and all the material referenced in it.
- b. The SONGS 2 & 3 Atomic Safety and Licensing Board hearing in 1981 and all the testimony presented at this hearing.
- c. "Analysis of 2/3g Housner Reanalysis Design Spectrum for San Onofre Nuclear Generating Station", Southern California Edison Co. February 23, 1982.
The supporting basis for this decision will be finalized upon receipt and evaluation of the following confirmatory information which the licensee has committed to provide:
- a. Justification of the Instrumental Response Spectra presented in Appendix B of the February 23, 1982 report.
- b. Reports from TERA Corp. entitled, "Estimation of Peak Horizontal Ground Acceleration at San Onofre Nuclear Generating Station"
- c. Report from TERA Corp. entitled "A Comparative Analysis of the Ground Motion Models of TERA Corporation and the U. S. Geological Survey."
- d. Finalized comparisons between the vertical and horizontal Housner Design Spectra ahd the various response spectra estimates discussed in the February 23, 1982 report.
- 2. The controlling earthquake for reanalysis of the SONGS 1 is (as specified in the SONGS 2 & 3 SER) M = 7.0 on the Offshore Zone of Deformation 8 km S
from the site.
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- 3. The horizontal (0.67g Housner) and vertical (0.44g Housner) design reanalysis spectra.proposed by the licensee are within the range of estimates of the 84th percentile free field response spectrum for that site.
Such individual estimates may exceed or be exceeded by the proposed reanalysis spectra over different frequency ranges.
- 4.
Based upon a comparison'of theoretical, empirical and probabilistic
-estimates it is our positi'on that while the Housner spectra are in general appropriate, our best estimates of the 84th percentile spectra from the controlling earthquake Would exceed the horizontal Housner spectra by up to 10% in the 0.07 to 0.25 second period range and the vertical Housner spectra by up to 10% in the 0.05 to 0.15 second period range.
- 5. The licensee has argued that estimates of the 84th free field spectra from the controlling earthquake should be compared to instrumental versions of the Housner design reanalysis spectra. The instrumental versions are increasdd from the design version taking into account ductility and soil structures interactions. It is our position, taken in concurrence with the SEP Branch, that such factors, to the extent that they are applicable, should be considered in the engineering analysis phase of the review rather than in the seismological input stage.
ENCLOSURE II Request for Additional Information SEP TOPIC 111-6 SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 DOCKET NO. 50-206 The NRC staff's best estimates of the 84th percentile spectra from the controlling earthquake would exceed the horizontal Housner Spectra by up to 10% in the period range from 0.07 second to 0.25 second and the vertical Housner Spectra by up to 10% in the period range from 0.05 second to 0.15 seconds Your responses to the following questions are requested:
- 1. Describe for each structure the effects of this increase in response spectra on the loadings (moments, shears, and buckling, etc.), 9tresses and displace ments which were calculated using linear elastic analysis and justify their adequacy.
- 2. Describe, for each of the structures, systems (e.g., reactor coolant loop), and components, the effects of this increase in response spectra on the calculated
-loadings-(moments, shears, and bucklings, etc.), stresses and displacements when either a nonlinear analysis or an inelastic response spectrum.analysis (using ductility concept) was used to account for inelastic behavior and justify their adequacy.
3.- Describe the effects of this-increase in response spectra on the calculated loadings (moments, shears, and buckling, etc.), stresses and displacements of masonry walls where nonlinear inelastic analyses were used. 'Justify that the integrity of these walls would not be compromised and equipment supported by or penetrating through these walls would not be adversely affected by this increase in response spectra.
- 4. Describe the effects of this increase in free field response spectra on the floor response spectra that were used for the qualifications and/or analyses of walls, piping, mechanical and electrical equipment and justify that the walls, piping, mechanical and electrical equipment are adequately designed.