ML13310B066
| ML13310B066 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 10/20/1983 |
| From: | Krieger R SOUTHERN CALIFORNIA EDISON CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-03.A, TASK-3-3.A, TASK-RR NUDOCS 8311100174 | |
| Download: ML13310B066 (4) | |
Text
Southern California Edison Company P.O. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 October 20, 1983 Director, Office of Nuclear Reactor Regulation Attention: 0. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Systematic Evaluation Program Topic III-3.A San Onofre Nuclear Generating Station Unit 1 The evaluation of SEP Topic III-3.A, "Effects of High Water Level on Structures," is provided in the enclosure. The results of the evaluation establish that except for the fuel storage and ventilation equipment buildings, all seismic Category I structures meet-current criteria. The fuel storage and ventilation equipment buildings failed to meet current criteria due to the effects of probable maximum precipitation on the rooftops. The need to implement corrective actions for these buildings will be determined during the integrated safety assessment.
Please contact me if you have any questions or require additional information.
Very truly yours, R. W. Krieg Supervising Engineer San Onofre Unit 1 Licensing Enclosure cc:
Document Control Desk, Washington D.C. (10)
'6 B;8311100174 831020 7
ENCLOSURE SAN ONOFRE NUCLEAR GENERATING STATION UNIT 1 DOCKET NUMBER: 50-206 SEP TOPIC III-3.A EFFECTS OF HIGH WATER LEVEL ON STRUCTURES I.
Introduction The acceptability of the original design basis high water level including dynamic effects for nuclear power plants is reviewed in SEP Topics II-3.A and B. Should the design basis level or dynamic effects increase from that assumed in the original design, the ability of plant structures to withstand this new loading is reviewed. The objective is to provide assurance that high water levels will not jeopardize the structural integrity of seismic Category I structures and that seismic Category I systems and components located within or on these structures will be adequately protected.
II.
Review Criteria Standard Review-Plan 3.4 defines analysis-procedures for flood loadings and Regulatory Guide,1.102 defines acceptable flood protection.
III.
Related Topics and Interfaces
- 1. Flood water levels and protection requirements are reviewed in SEP Topics II-3.A and B.
- 2. Inservice inspection requirements for water control structures are reviewed in SEP Topic III-3.C.
- 3. Classification of structures which need be seismic Category I is reviewed in SEP Topic III-1.
IV.
Review Guidelines A review of the structural design procedures and design loadings for flooding at the site was conducted by examining the docket files and comparing the stated design parameters with current criteria as outlined in the Standard Review Plan and Regulatory Guides.
This review is dependent upon the evaluation of SEP Topics II-3.A, 3.B, 3.B.1 and 3.C. Reference 1 provided us with a draft of this evaluation.
Our comments, which identify errors in the draft and supply corrected as well as additional information, were provided by Reference 2.
Therefore, this review was conducted based on the information provided in Reference 2.
-2 V.
Evaluation
- 1. Effect of Probable Maximum Flood References 1 and 2 discuss the physical flood protection system at San Onofre Unit 1. This system was designed to prevent flooding of safety related equipment required for safe shutdown or accident mitigation. Reference 2 indicates that water will pond to
+12.61 feet MLLW at the lowest plant elevation during a probable maximum flood (PMF).
Reference 3 identifies the lowest:
nonwatertight opening of structures housing safety related equipment as +14 feet MLLW. Therefore, the physical flood protection system prevents flood penetration via a nonwatertight opening in structures housing safety related equipment. In addition, structures housing safety related equipment were designed to withstand the dynamic effects of a PMF.
- 2. Effect of Probable Maximum Precipitation Reference 1 discusses the effect of probable maximum precipitation (PMP) on rooftop integrity of structures whose failure could impact safety related equipment. All structures except for the fuel storage building and the ventilation equipment building were found to meet current criteria. The design bases for these buildings were unavailable to the NRC at the time of the NRC evaluation.
These design bases and an evaluation of the effect of PMP on the rooftops of these buildings were sUbsequently provided by Reference 2. The evaluation indicates that the fuel storage building and the ventilation equipment building fail to meet current criteria.
- 3. Effect of Probable Maximum Tsunami The confined plant area is protected from a probable maximum tsunami (PMT) by the tsunami wall complex consisting of the seawall, the riprap berm and the beach walkway retaining wall as discussed in Reference 1 (SEP Topic II-3.B).
Reference 1 indicates that the maximum wave run-up on the seawall due to a PMT is
+27.9 feet MLLW. Since the top of the seawall is +28.2 feet MLLW, San Onofre Unit 1 is adequately protected from a PMT. References 4 and 5 indicate that the tsunami wall complex meets current criteria with respect to the design basis earthquake (DBE) and tsunami load combinations (SEP Topic 111-6).
- 4. Effect of Groundwater Reference 2 identifies the design basis groundwater level as
+5 feet MLLW for subsurface hydrostatic loading and for loading combination with design basis events. San Onofre Unit 1 structures have been adequately designed to withstand a groundwater level of
+5 feet MLLW. In addition, no safety related equipment will be flooded by groundwater penetration through a nonwatertight opening since the lowest such opening is +14 feet MLLW as discussed above.
-3 VI.
Conclusions The confined plant site is adequately protected from a PMF condition by the existing physical flood protection system. The plant is also protected from extreme high ocean levels and from a PMT by the tsunami wall complex. Nonwatertight openings of structures housing safety related equipment are located sufficiently above PMF and groundwater levels to prevent flooding of safety related equipment due to water penetration through a nonwatertight opening. Rooftops of structures whose failure could impact safety related equipment are adequately designed to handle a PMP condition, except for the fuel storage and ventilation equipment buildings. The need to implement corrective actions for the fuel storage and ventilation equipment buildings will be determined in the integrated safety assessment.
VII.
References
- 1. January 31, 1983 letter from D. M. Crutchfield, NRC, to R. Dietch, SCE;
Subject:
Draft Evaluation of SEP Hydrology Topics
- 2. October 5, 1983 letter from R. W. Krieger, SCE, to 0. M.
Crutchfield, NRC;
Subject:
Comments on Draft Evaluation of SEP Hydrology Topics
- 3. April 12, 1982, letter from R. W. Krieger, SCE, to D. M. Crutchfield, NRC;
Subject:
Transmittal of Response to Request for Additional Information on SEP Hydrology Topics
- 4. December 8, 1981 letter from K. P. Baskin, SCE, to
- 0. M. Crutc hfield, NRC;
Subject:
SEP Topic 111-6 Seismic Design Considerations
- 5. September 1, 1983 letter from K. P. Baskin, SCE, to
- 0. M. Crutchfield, NRC;
Subject:
SEP Topic II-4.F GRoche:9209