ML13317B246
| ML13317B246 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/03/1990 |
| From: | Rainsberry J SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-14, NUDOCS 9012070121 | |
| Download: ML13317B246 (4) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE. CALIFORNIA 92718 December 3, 1990 U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Generic Letter 88-14, 'Instrument Air Supply System Problems Affecting Safety-Related Equipment' San Onofre Nuclear Generating Station, Unit 1 BACKGROUND This letter provides additional information in response to Generic Letter 88-14. By letter dated August 30, 1990 SCE responded to the generic letter indicating that we have completed all of the requirements with the exception of six open items. This letter provides you with the results for three of these items: (1) loss of normal instrument air valve fail-safe position testing; (2) review of our instrument air blowdown and inspection program, and (3) review of post-installation testing for valves equipped with safety-related nitrogen backup supply. The remaining information will be provided later as previously committed.
LOSS OF NORMAL INSTRUMENT AIR VALVE FAIL-SAFE POSITION TESTING An analysis of failure positions for the safety-related air-operated valves was performed to verify that these positions are correct for assuring required safety functions. Based on this analysis, we conducted loss of normal instrument air valve fail-safe position testing to verify that the actual failure position is consistent with the analyzed fail-safe position.
Results The loss of normal Instrument Air valve fail-safe position testing has been completed. The testing confirmed that for all safety-related air-operated valves with the exception of CV-406B, the actual fail-safe position is consistent with the analyzed fail-safe position. During testing, valve CV-406B in the Chemical Volume and Control System failed in the direction opposite to the analyzed fail-safe position. LER 90-006 addresses this problem and the corrective actions implemented.
DYo::
FFUR
- tIlc7 O) 5 0c)Q)2
Document Control Desk December 3, 1990 INSTRUMENT AIR SYSTEM BLOWDOWN AND INSPECTION PROGRAM As a result of the 1980 desiccant breakdown incident, we instituted an Instrument Air System inspection program. The purpose of the inspection program was to verify that the desiccant and moisture had been removed from the Instrument Air System and to confirm the effectiveness of the new filtration system. During refueling outages, the supply lines and inlet filters to various components were inspected for evidence of desiccant and moisture. In response to the generic letter, we performed a review to determine the adequacy of our inspection program.
Results Based on our review of previous refueling-interval inspections, we conclude that the Instrument Air System is clean and dry. The previous inspection program provided a comprehensive assessment of Instrument Air System cleanliness by addressing 388 safety-related components. Based on the satisfactory results of this program, we have concluded that a reduction in scope of the program is appropriate. The revised program monitors 12 strategic locations throughout the Instrument Air System. As with the previous program, these inspections will be performed on a refueling interval frequency.
POST-INSTALLATION TESTING OF VALVES EQUIPPED WITH NITROGEN BACKUP SYSTEM Verification of the functional testing for valves which are served by the Instrument Air System and have a Safety-Related Nitrogen Backup System has been completed. Functional testing of these valves was performed following installation of the Nitrogen Backup System. We are crediting the post-installation testing of these valves to meet the design verification requirements of the generic letter.
Results Our review of the post-installation test records has verified that all testing met current post-installation standards. The post-installation testing verified that the sizing and operation of the Safety-Related Nitrogen Backup System ensures that these valves will perform their intended safety function when required during a design basis event.
OPEN ITEM SCHEDULE The three remaining items will be provided as indicated in our letter of August 30, 1990. The results from the air quality laboratory tests and the Instrument Air System flowrate measurements will be provided to you within six months of return to service from the Cycle 11 refueling outage. Finally, to complete our response to the generic letter, by the end of the Cycle 12 refueling outage, we will provide you with the results from the Cycle 12 refueling outage inspection of the Instrument Air System. The inspection results will verify our conclusion that the September 1989 failure of a solenoid valve supplied from the Instrument Air System was an isolated incident of residual desiccant.
Document Control Desk December 3, 1990 CONCLUSION As stated in our August 30, 1990 response to Generic Letter 88-14 we have provided you with the results for the following open items: (1) loss of normal instrument air valve fail-safe position testing, (2) review of our instrument air blowdown and inspection program, and (3) review of post-installation testing for valves equipped with safety-related nitrogen backup supply. With this submittal these three items are completed.
If you have any questions regarding this matter, please let me know.
Respectfully submitted, By:
C
. A4nsberry S pervising Enginee uclear Licensing Subscribed and sworn o before me t 's (L
day of ;i-h
, A lys.
Notary Public in the State of California cc: J. B. Martin, Regional Administrator, NRC Region V C. W. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 C. D. Townsend, NRC Resident Inspector, San Onofre Unit 1
Vt