ML13322B103
| ML13322B103 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/09/1990 |
| From: | Morgan H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 9003050007 | |
| Download: ML13322B103 (2) | |
Text
Southern California Edison Company SAN ONOFRE NUCLEAR GENERATING STATION P. 0.
BOX 128 SAN CLEMENTE, CALIFORNIA 92672
'9 H. E. MORGAN February 9, 1990 TELEPHONE STATION MANAGER (714) 368-6241 Mr. John B. Martin U. S. Nuclear Regulatory Commission, Region V 1450 Maria Lane, Suite 210 Walnut Creek, California 94596
Subject:
Request for Temporary Relief From Technical Specification 3.4.3 San Onofre Nuclear Generating Station, Unit 1 Dear Mr. Martin This letter is a follow up to SCE's oral request to Mr. C. Caldwell for temporary relief from Technical Specification (TS) 3.4.3, "Auxiliary Feedwater System," in order to maintain Unit 1 in Mode 3 to continue trouble shooting and repairs on the steam driven Auxiliary Feedwater (AFW) pump G-10.
TS 3.4.3 defines AFW Train "A" to include both an electrically driven AFW pump and the steam driven AFW pump. AFW pump G-10 has been inoperable since 8:39 am, February 7, 1990, due to unidentified problems with the turbine over-speed trip mechanism. NRC action is required at this time in order to preclude imposing unnecessary transients resulting from anticipated recurring mode changes between HOT STANDBY and HOT SHUTDOWN. The AFW pump was previously believed to be operable and the problems discussed below were discovered during the normal monthly surveillance test. As a result, SCE could not have reasonably foreseen the need for relief from this TS.
Specifically, SCE requests to remain in Mode 3 for an additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> permitted by the TS during POWER OPERATION (until 8:39 am PST, February 13, 1990).
This additional time in HOT STANDBY is necessary so that steam at sufficient pressure will be available for diagnostic testing of the turbine over-speed trip mechanism. If SCE complies with the TS 3.4.3 action statement requirements, the unit will be required to enter HOT SHUTDOWN and, as a consequence, there would be insufficient steam pressure available to determine and correct the cause of the low overspeed trip.
Continued operation in HOT SHUTDOWN during this additional period is considered prudent since two independent electrically driven AFW pumps remain operable.
Further, each motor driven AFW pump (G-10S and G-10W) is individually capable of required heat load removal six hours after a shutdown from full power.
During the requested period of relief, SCE plans are as follows:
- 1.
Restore the turbine driven AFW pump to operability and return to POWER OPERATION (Mode 1).
Or, F R FF:c
~
7 -~0
Mr. J. B. Martin February 9, 1990 Page 2
- 2.
If a definitive cause of the pump problem is determined (eliminating the need for continued troubleshooting and testing) the unit will be placed in HOT SHUTDOWN to effect repairs. Or,
- 3.
Should our efforts over the weekend to identify and correct the problem be unsuccessful, further discussions will be initiated with your office on Monday, February 12, 1990.
Should you require any additional information, please so advise.
cc:
C. W. Caldwell (USNRC Resident Inspector, Units 1, 2, and 3)
R. Zimmerman (USNRC, Region V)