ML13330A337
| ML13330A337 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/07/1981 |
| From: | Baskin K Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR NUDOCS 8107100034 | |
| Download: ML13330A337 (12) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 K. P. BASKIN Jul 7
TELEPHONE MANAGER OF NUCLEAR ENGINEERING, y
1981 (213) 572.1401 SAFETY, AND LICENSING Director of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555 J UL0 9 198
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Gentlemen:
tas esWuuma
Subject:
SEP Topic 111-6 Seismic Design Considerations San Onofre Nuclear Generating Station Unit 1 Your letter of April 24, 1981 requested that we submit our seismic reevaluation program for San Onofre Unit 1. This program was subsequently discussed with members of the NRC staff in meetings on June 1 and 9, 1981.
Various activities pertaining to the seismic reevaluation of San Onofre Unit 1 have previously been reported to the NRC.
For completeness, all aspects of the seismic reevaluation of San Onofre Unit 1, whether completed or ongoing, are summarized in Enclosure 1 to this letter. A more detailed description of the scope of the program for the seismic reevaluation of balance of plant mechanical equipment and piping is provided as Enclosure 2.
A detailed description of the methodology and criteria for the balance of plant mechanical equipment and piping program will be provided by August 14, 1981.
As discussed with the NRC, it is SCE's intention to evaluate on a case-by-case basis modifications shown to be necessary by the seismic analyses. In cases where these modifications are not likely to be affected by other SEP topic evaluations, it is SCE's intention to initiate design, procurement and construction of the modifications following completion of the analyses. In these cases, it is anticipated that the modifications will be implemented during the first plant outage of sufficient duration following completion of the analysis, design and procurement. For modifications which are likely to be impacted by other SEP topic evaluations, it is our intention to consider these modifications during the SEP integrated assessment. In these cases, SCE will identify the potential modification to the NRC and 0e17100034 910707 PDR ADOCK 050002 6 P
0 0
D. M. Crutchfield, Chief
-2 provide the basis for delaying implementation of the modifications.
Notwithstanding the above considerations, if as a result of the seismic reevaluation program, it is determined that any structure, component or piping being reevaluated does not meet the original design basis, this will be reported to the NRC and appropriate corrective action taken. Moreover, as discussed with the NRC, it is our intention to proceed with implementation of, modifications to the north and west platforms of the turbine building foll6wing completion of the analyses of these structures. These modifications will be implemented independent of any other SEP considerations.
The adequacy of the seismic design of San Onofre Unit 1 during the time that the seismic reevaluation is being performed was discussed in our April 28, 1980 letter to the NRC. A number of independent items are discussed in that letter, the combination of which leads us to conclude that San Onofre Unit 1 can continue to operate during the time required to perform the seismic reevaluation without undue risk to the health and safety of the public.
If you have any questions on any of this information, please let me know.
Subscribed on this day of A.
1981.
Very ruly yours, SOUTHERN CALIFORNIA EDISON COMPANY By K. P. Baskin Manager of Nuclear Engineering, Safety, and Licensing Subscrib d and swor to before me this 7-day of
, 1981 AGNES CRABrTREE NOTARY uSiuc - cGuNMiIA P
OFFICE lIN
-4LOS ANGEM ODUNTY, Z AZ CYoDmmiso Ftp:-Aug.27,1982 NotargPublic in and for the County of LM~ Angeles, State of California
ENCLOSURE 1 ACTIVITIES PERTAINING TO THE SEISMIC REEVALUATION OF SAN ONOFRE UNIT 1 I.
Introduction This report provides a summary of the various activities associated with the seismic reevaluation of San Onofre Unit 1. All activities, whether completed or ongoing, are included. The following specific areas are discussed:
(1) the Site Specific Response Spectra, (2) structures, (3) electrical equipment, and (4) mechanical equipment and piping.
II. Site Specific Response Spectra Since 1976, SCE has pursued a significant program to establish conservative estimates of ground shaking at the San Onofre site. This program has consisted of development of a detailed computer model that simulates the physical processes of earthquakes to extrapolate site specific ground motions from past earthquakes. This work has been documented in several submittals (References 1 to 4) and discussed in several meetings with the NRC and their consultants. This work has continually supported the conservatism of the 2/3g Housner response spectrum, which is being used for the seismic reevaluation of San Onofre Unit 1.
III.
Structures With respect to seismic reevaluation, structures at San Onofre Unit 1 can be divided into three categories:
(1) the diesel generator and sphere enclosure buildings which were designed to the San Onofre Units 2 and 3 response spectrum, (2) the containment sphere and reactor building which were previously reevaluated to 2/3g Housner, and (3) structures currently being reevaluated to 2/3g Housner as part of the Balance of Plant Structures (BOPS) Seismic Reevaluation Program.
A. Diesel Generator and Sphere Enclosure Buildings The design of the diesel generator and sphere enclosure buildings was documented in References 5 through 8. Since these structures were designed to the San Onofre Units 2 and 3 response spectrum, no further work is planned for these structures.
B. Containment Sphere and Reactor Building The containment and the reactor building were reevaluated in 1974-1975 to the 2/3g Housner response spectrum and found to be adequate. These evaluations are documented in Reference 9 and additional information is provided in Reference 10. Since these structures were reevaluated to the 2/3g Housner response spectrum, no further work is planned for these structures.
-2 C. 80PS Seismic eeva uation Program A detailed description of the methodology and criteria for the BOPS Seismic Reevaluation Program was provided by Reference 11 and the current schedule for the program was provided by Reference 12. As described in References 11 through 14, the BOPS Seismic Reevaluation Program also incorporates the seismic evaluation of masonry walls as required by IE Bulletin 80-11. SCE is presently 100% complete with model development and is proceeding with the computer analyses. The analyses are scheduled for completion by October of 1981.
As discussed in Reference 12, an integral part of this program is the consideration of assumed modifications prior to initiating detailed analyses. To date, as part of the modeling effort modifications have been identified for the turbine building and the fuel storage building.
It is our intention to evaluate these modifications as well as any other modifications which may be identified as a result of the analyses to determine whether these modifications will be impacted by other SEP topic evaluations and therefore should be deferred to the SEP integrated assessment.
Irrespective of any evaluation of the impact of other SEP topics, SCE intends to proceed with implementation of modifications to the north and west platforms of the turbine building following completion of the analyses of these structures. These modifications are being expedited at the request of the NRC Staff due to the proximity of the structures to the auxiliary feedwater system piping and components. Based on the current schedule, these analyses will be complete by October 1, 1981. It is anticipated that detailed engineering and design will require three to six months. Construction will be completed during the first outage of sufficient duration following completion of design and procurement. Although we cannot estimate the construction time required until the modifications are designed, it is our intention, if possible, to install these modifications during the outage currently scheduled for six effective full power months following startup from the recent outage. We will advise you following completion of the analyses of our ability to meet this schedule.
IV. Electrical Equipment The evaluation of electrical equipment at San Onofre Unit 1 can be divided into 1) the evaluation of the anchorage of electrical equipment,
- 2) the evaluation of the operability of electrical equipment, and 3) the evaluation of cable trays.
-3 A. Anchorage of Electrical Equipment The anchorage of safety-related electrical equipment was reevaluated to 2/3g Housner during the past year. These evaluations are documented in References 15 and 16.
All modifications found to be necessary as a result of these analyses were implemented during the past outage.
No further work is planned for this item.
B. Operabililty of Electrical Equipment As indicated in Reference 17, SCE has been investigating the seismic adequacy of electrical equipment on a generic basis with the other members of the SEP Owners Group. Subsequent to that letter, the SEP Owners Group contracted with Westinghouse to pursue this issue. This program which involves criteria development and data acquisition was outlined in a presentation to the NRC on March 5, 1981.
SCE will continue to pursue this program with the SEP Owners Group. The results of Westinghouse's efforts will be completed later this year. Following receipt of these results, it is anticipated that the evaluation of the qualification of equipment will require an additional 1 to 2 years.
C. Cable Trays As described in Reference 18, SCE was one of a number of utilities which participated in a generic cable tray testing program with Bechtel Power Corporation. These tests are summarized in Reference 19 a copy of which was provided to the NRC in a meeting with Bechtel on January 8, 1980. It is SCE's intention to perform an evaluation of the cable trays at San Onofre Unit 1 based on the results of the Bechtel testing program.
An action plan and schedule for the evaluation of cable trays was provided in Reference 18. It is now anticipated that the evaluation of accessible cable trays will be completed by January 1, 1982. The evaluation of inaccessible cable trays will be completed during the next extended plant outage presently scheduled for January, 1982.
V.
Mechanical Equipment and Piping Mechanical equipment and piping can be divided into five categories with respect to seismic reevaluation: 1) the diesel generators and associated equipment, piping and tanks, 2) the reactor coolant system (RCS) main loop and components, 3) reactor coolant pressure boundary (RCPB) piping and valves, 4) safe shutdown system piping, equipment and tanks, and 5) accident mitigating system piping and equipment.
-4 A. Diesel Generators The design of the diesel generators and associated equipment, piping and tanks was documented in Reference 5. Since this equipment was designed to the San Onofre Units 2 and 3 response spectrum, no further work is planned for these structures.
B. RCS Main Loop and Components The RCS main loop piping and major NSSS components including the steam generators, pressurizer, reactor coolant pumps, reactor vessel, fuel elements, control rod assemblies and control rod drives were reevaluated in 1974 to 1976 to the 2/ 3g Housner response spectrum. Modifications required as a result of these evaluations were implemented during the 1976-1977 plant outage.
These evaluations and modifications were documented in Reference 9 and additional information was provided in Reference 10. Since these piping and components were reevaluated and modified as necessary to the 2/3g Housner response spectrum, no further work is planned for thesepiping and equipment.
C.
RCPB Piping and Valves The seismic reevaluation of the RCPB piping and valves is part of the Balance of Plant Mechanical Equipment and Piping (BOPMEP)
Seismic Reevaluation Program. A description of the scope of this program is provided as Enclosure 2 to this letter. A description of the methodology and criteria to be used for this evaluation will be provided by August 14, 1981. It is anticipated that the reevaluation of RCPB piping and valves will be completed by March 1, 1982.
D. Safe Shutdown Systems Piping, equipment and tanks associated with safe shutdown systems are being reevaluated as part of the BOPMEP Seismic Reevaluation Program described in Enclosure 2. Methodology and criteria will be provided by August 14, 1981.
It is anticipated that the reevaluation of the safe shutdown system piping, equipment and tanks will be completed by March 1, 1982.
E. Accident Mitigating Systems Piping and equipment associated with accident mitigating systems, including emergency core cooling, containment spray and containment isolation, will be reevaluated as part of the BOPMEP Seismic Reevaluation Program described in Enclosure 2. Methodology and criteria will be provided by August 14, 1981. It is anticipated that the reevaluation of accident mitigating systems will be completed by November 1, 1982.
-5 VI.
Conclusion The preceeding sections have discussed all aspects of the seismic reevaluation of San Onofre Unit 1. Major reevaluation and modifications completed to date have been summarized. It should be noted that more limited analyses and modifications have not been specifically described. For example, SCE has inspected piping support details as a result of IE Bulletin 79-14.(Reference 20) and reevaluated various sections of piping on a case by case basis (Appendix A of Enclosure 2 to Reference 21).
In addition, reevaluation programs currently in progress are outlined in the preceeding sections along with the schedules for completion of these programs.
To date, SCE has reevaluated to 2/3g Housner and modified, as necessary, the components and piping which could precipitate a major accident and the primary feature for protection of the public in the event of an accident.
By March 1, 1982, SCE is scheduled to have reevaluated the remainder of the primary coolant pressure boundary, thereby precluding a loss of coolant accident, and all structures and mechanical systems required to bring the plant to a safe shutdown. However, the reevaluation program will go beyond that to also include necessary accident mitigating systems.
VII.
References
- 1. Letter from K. P. Baskin to D. L. Ziemann dated May 26, 1978, Site Specific Earthquake Program
- 2.
Letter from K. P. Baskin to D. L. Ziemann dated July 12, 1979, Site Specific Earthquake Program.
- 3. Letter from J. G. Haynes to D. M. Crutchfield dated August 8, 1980, Site Specific Earthquake Program.
- 4.
Letter from J. G. Haynes to D. M. Crutchfield dated August 13, 1980, Site Specific Earthquake Program.
- 5. Letter from J. B. Moore to E. G. Case dated February 7, 1975, Amendment No. 38.
- 6. Letter from J. B. Moore to B. C. Rusche dated December 3, 1975, Amendment No. 52.
- 7. Letter from J. B. Moore to R. A Purple dated March 1, 1976, Supplement to Sphere Enclosure Project Report.
- 8. Letter from K. P. Baskin to K. R. Goller dated March 25, 1976, Second Supplement to Sphere Enclosure Project Report.
-6
- 9. Letter from K. P. Baskin to A. Schwencer dated May 18, 1977, Seismic Reevaluation and Modifications.
- 10. Letter from K. P. Baskin to D. L. Ziemann dated April 11, 1980, Seismic Backfit Project and Site Specific Earthquake Program.
- 11.
Letter from K. P. Baskin to D. M. Crutchfield dated February 23, 1981, SEP Topic 111-6, Seismic Design Considerations.
- 12.
Letter from K. P. Baskin to D. M. Crutchfield dated April 24, 1981, SEP Topic 111-6, Seismic Design Considerations.
- 13.
Letter from H. L. Ottoson to R. H. Engelken dated July 17, 1980, IE Bulletin No. 80-11, Masonry Wall Design.
- 14. Letter from J. G. Haynes to R. H. Engelken dated November 10, 1980, IE Bulletin No. 80-11, Masonry Wall Design.
- 15. Letter from K. P. Baskin to D. M. Crutchfield dated March 25, 1981, Anchorage and Support of Safety Related Electrical Equipment.
- 16. Letter from K. P. Baskin to D. M. Crutchfield dated May 29, 1981, Anchorage and Support of Safety Related Electrical Equipment.
- 17.
Letter from K. P. Baskin to D. M. Crutchfield dated September 24, 1980, (Seismic Reevaluation Program).
- 18. Letter from K. P. Baskin to D. M. Crutchfield dated August.29, 1980, Seismic Design of Cable Trays.
- 19. Cable Tray and Conduit Raceway Seismic Test Program, December 15, 1978.
- 20. Letter from J. G. Haynes to R. H. Engelken dated June 2, 1981.
- 21.
Letter from K. P. Baskin to D. L. Ziemann dated April 28, 1980, Seismic Reevaluation Program.
ENCLOSURE 2 BALANCE OF PLANT MECHANICAL EQUIPMENT AND PIPING (BOPMEP)
SEISMIC REEVALUATION PROGRAM SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 1.0 PROGRAM OBJECTIVE The objective of this program is to reevaluate balance of plant mechanical equipment and piping that are required to achieve cold shutdown after a Design Basis Earthquake of 2/3g with a Housner response spectrum. Excluded from this reevaluation will be those systems considered to be qualified by previous programs. This includes the diesel generators and associated equipment which were designed to the San Onofre Units 2 and 3 response spectrum and the portions of the Reactor Coolant System which were reevaluated and modified to the 2/3g Housner response spectrum.
2.0 PROGRAM SCOPE 2.1 GENERAL The scope of the BOPMEP Seismic Reevaluation Program will consist of:
A. The remainder of the Reactor Coolant Pressure Boundary (RCPB) not previously reevaluated; B. The piping, equipment and field erected tanks necessary to bring the plant to a safe cold shutdown condition (less than 200 0F).
This includes boration of the Reactor Coolant System (RCS), heat removal, depressurization of the RCS and miscellaneous supporting functions.
C. Piping and equipment required to mitigate a loss of coolant or secondary line break, including emergency core cooling, containment spray and containment isolation systems.
2.2 SYSTEMS The following is a description of the plant systems to be reevaluated.
2.2.1 Reactor Coolant Pressure Boundary A. The RCPB includes piping and valves which are connected to the RCS, up to an including the following:
(a) The outermost containment isolation valves in piping which penetrates the containment sphere.
(b) The RCS safety and relief valves.
-2 (c) Piping, fittings and valves leading to connecting systems up to an including the first normally closed valve (from the high pressure side) or the first normally open valve capable of automatic or remote manual closure.
2.2.2 Safe Shutdown Systems Systems listed below which are required to bring the plant to a safe cold shutdown will be reevaluated. System boundaries will include all connected piping up to an including the first valve that is normally closed or capable of automatic or remote manual closure when the safe shutdown is required.
A. Boration and Depressurization Function (a) Portions of the Chemical and Volume Control System (CVCS) that supply borated water from the Refueling Water Storage Tank (RWST) to the RCS via the normal charging lines and the auxiliary spray line to the pressurizer.
(b) Portions of the Miscellaneous Water System which ensure pressure boundary integrity of the RWST and piping to the CVCS.
B Heat Removal Function (a) Portions of the Main Steam System required to remove decay heat from the RCS by venting steam to the atmospheric steam dump valves in the main steam relief header.
(b) Portions of the Condensate and Feedwater System and Auxiliary Feedwater System required to provide makeup to the steam generators.
(c) Portions of the Auxiliary Coolant System required to remove decay heat in going from hot shutdown to cold shutdown including Residual Heat Removal system piping and equipment. In addition, all portions of the Auxiliary Coolant System required to support equipment cooling requirements and maintain its pressure boundary will be reevaluated. Piping and equipment connected to the spent fuel pool will be reevaluated to ensure integrity of the fuel pool.
Means will be investigated to supply makeup to the pool as needed.
(d) The Salt Water Cooling System from the intake structure to the component cooling water heat exchangers.
-3 C. Miscellaneous Support System To support the primary functions noted above, instrument air and service water will be reevaluated insofar as they support the capability to effect a safe cold shutdown.
2.2.3 Accident Mitigating Systems The following accident mitigating systems will be reevaluated.
System boundaries will include all connected piping up to an including the first valve that is normally closed or capable of automatic or remote manual closure following an accident.
A. Safety injection piping, valves and pumps from the RWST to the RCS.
B. Hydrazine addition system.
C. Containment spray piping, valves and pumps.
D. Containment isolation piping and valves including the containment purge and vent valves.
2.3 PROGRAM BASIS The following conditions which are outside the scope of this program form the basis for the program.
A. The RCPB is maintained.
B. Offsite power is not available for powering any equipment required to achieve safe shutdown. Therefore, power will be supplied by the diesel generator onsite power system.
C. All electrical circuitry and devices associated with controls and instrumentation required to perform the required automatic or remote manual functions are available and functional.
D.
The contraction of the RCS inventory in going from power to cold shutdown is sufficient to eliminate the need for letdown equipment.
Makeup will be from the RWST.
E. The RCS has sufficient capability to transfer both decay and sensible heat to the secondary system by natural circulation.
F. The pressurizer heaters remain operable and provide the means for maintaining RCS pressure and boron equalization during extended operation at hot shutdown.
G. Reactor trip capability is fully maintained.
-4 3.0 PROGRAM APPROACH Reevaluation approaches being considered include, but are not necessarily limited to, the following:
A. Analysis B. Similarity C. Testing D. Field Evaluation E. Declassification by the addition of isolation valves or by safety analysis.