ML13308B453
| ML13308B453 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/07/1977 |
| From: | Head J Southern California Edison Co |
| To: | Engelken R NRC Office of Inspection & Enforcement (IE Region V) |
| References | |
| NUDOCS 8103050956 | |
| Download: ML13308B453 (8) | |
Text
REUAeyDg"!ffr C"
0 p Y Southern California Edison Company P 0. BOX 800 2244 WALNUT GROVE AVENUE J. T. HEAQ, JR.
ROSEMEAD, CALIFORNIA 91770 TELEPHONE VICE PRESIDENT 213-572-1472 September 7, 1977 SE~
RCEIVEP<$'
uL 1977 4!i
.. NUCLEA 1 '67 j~ra U. S. Nuclear Regulatory Commission R RCOM ssoitr Region V
- qlym Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Attention
- Mr. R. H. Engelken, Director Docket No. 50-206 San Onofre Unit 1
Dear Sir:
References:
(1) Letter from SCE (H. L. Ottoson) to USNRC, Region V dated August 24, 1977 (2) Letter from SCE (K. P. Baskin) to NRC (A. Schwencer) dated March 25, 1977 re: Plant Modifications to Eliminate Postulated Single Failure Effects (3) Letter from SCE (K. P. Baskin) to NRC (A. Schwencer) dated December 21, 1976 re:
Single Failure Analysis Reference (1) provided notification to the Regional Office of a deficiency in the charging pump circuitry as recently revised in order to eliminate undesirable single failure effects.
"A This letter is the followup report to Reference (1) and is sub mitted in accordance with the provisions of Section 6.9.2a of Appendix A to the Provisional Operating License No. DPR-13.
1I6 "b O9 %v A
-2 Reference (2) indicated our intention to remove one charging pump from equipment automatically started by the sequencer as an interim measure to eliminate undesirable single failure effects discussed in the single failure analysis submitted by Reference (3).
Removal of one charging pump from equipment automatically started by the sequencer eliminates the potential failure of both charging pumps (one of which is needed during recirculation) as a result of the postulated failure, in an open position, of MOV/LCV 1100C. MOV/LCV 1100C isolates the hydrogen pressurized Volume Control Tank from the suction of the charging pumps. Without such isolation, hydrogen from the Volume Control Tank could cause the cavitation of the charging pumps.
The interim measure identified above was completed as part of Design Change 77-05 prior to return to operation of San Onofre Unit 1 in April 1977. Subsequent to the completion of Design Change 77-05 and the return to operation of San Onofre Unit 1, it was discovered that Design Change 77-05 did not eliminate the automatic starting of both charging pumps in the event of a loss of the 480V power supply to MOV/LCV 1100C. Loss of the MOV/LCV 1100C 480V power supply results in the deenergizing of a relay which normally isolates the standby*
charging pump from the auto start signal from the sequencer. De energization of this relay enables the automatic starting of the standby charging pump with a start signal from the sequencer. Design Change 77-05 did not, therefore, effect the desired interim measure, namely, the removal of one charging pump from equipment automatically started by the sequencer.
As indicated in Reference (1), redesign of the charging pump circuitry to correct the above-described deficiency has been initiated. The redesign consists of replacing the isolating capa bility of the above-identified relay with a manual alignment switch for each charging pump control circuitry. This redesign eliminates the automatic starting of both charging pumps by the sequencer and satisfies the requirements of the interim measure identified in Reference (2).
Additional details of the deficiency and the re design will be provided by separate cover.
The redesign has been reviewed and approved by the On-Site Review Committee (OSRC) as Design Change 77-10 in accordance with the Appendix A Technical Specifications. The redesign will be implemented during the next plant outage which is now scheduled to begin September 8, 1977. Until this redesign is implemented, administrative procedures have been implemented to assure that one charging pump will be available for recirculation service. A temporary operating memorandum has been put into effect which provides for operator action to prevent the loss of one charging pump in the event MOV/LCV 1100C loses its 480V power supply during a LOCA.
- As indicated in Reference (2) the standby charging pump is that pump not automatically started by the sequencer and therefore made available for subsequent recirculation service.
-3 Enclosed is a completed Licensee Event Report form designated LER 77-11.
If you have any questions concerning this matter please let me know.
incerely Enclosure cc:
Director, Office of Inspection and Enforcement (40 copies)
Director, Office of Management Information & Program Control (3 copies)
Southern California Edison pmpany c
P. 0. BOX 800 2244 WALNUT GROVE AVENUE J. T. HEAD, JR.
ROSEMEAD, CALIFORNIA 91770 TELEPHONE VICE PRESIDENT 213-572-1472 September 7, 1977 U. S. Nuclear Regulatory Commission Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Attention: Mr. R. H. Engelken, Director Docket No. 50-206 San Onofre Unit 1
Dear Sir:
References:
(1) Letter from SCE (H. L. Ottoson) to USNRC, Region V dated August 24, 1977 (2) Letter from SCE (K. P. Baskin) to NRC, (A. Schwencer) dated March 25, 0
1977 re: Plant Modifications to Eliminate Postulated Single Failure Effects (3) Letter from SCE (K. P. Baskin) to NRC (A. Schwencer) dated December 21, 1976 re:
Single Failure Analysis Reference (1) provided notification to the Regional Office of a deficiency in the charging pump circuitry as recently revised in order to eliminate undesirable single failure effects.
This letter is the followup report to Reference (1) and is sub mitted in accordance with the provisions of Section 6.9.2a of Appendix A to the Provisional Operating License No. DPR-13.
0940:OvOno
-2 Reference (2) indicated our intention to remove one charging pump from equipment automatically started by the-sequencer as an interim measure to eliminate undesirable single failure effects discussed in the single failure analysis submitted by Reference (3).. Removal of one charging pump from equipment automatically started by the sequencer eliminates the potential failure of both charging pumps (one of which is needed during recirculation) as a result of the postulated failure, in an open position, of MOV/LCV 1100C. MOV/LCV 1100C isolates the hydrogen pressurized Volume Control Tank from the suction of the charging pumps. Without such isolation, hydrogen from the Volume Control Tank could cause the cavitation of the charging pumps.
The interim measure identified above was completed as part of Design Change 77-05 prior to return to operation of San Onofre Unit 1 in April 1977. Subsequent to the completion of Design Change 77-05 and the return to operation of San Onofre Unit 1, it was discovered that Design Change 77-05 did not eliminate the automatic starting of both charging pumps in the event of a loss of the 480V power supply to MOV/LCV 1100C.
Loss of the MOV/LCV 1100C 480V power supply results in the deenergizing of a relay which normally isolates the standby*
charging pump from the auto start signal from the sequencer. De energization of this relay enables the automatic starting of the standby charging pump with a start signal from the sequencer.. Design Change 77-05 did not, therefore, effect the desired interim measure, namely, the removal of one charging pump from equipment automatically started by the sequencer.
As indicated in Reference (1), redesign of the charging pump circuitry to correct the above-described deficiency has been initiated. The redesign consists of replacing the isolating capa bility of the above-identified relay with a manual alignment switch for each charging pump control circuitry.
This redesign eliminates the automatic starting of both charging pumps by the sequencer and satisfies the requirements of the interim measure identified in Reference (2).
Additional details of the deficiency and the re design will be provided by separate cover.
The redesign has been reviewed and approved by the On-Site Review Committee (OSRC) as Design Change 77-10 in accordance with the Appendix A Technical Specifications. The redesign will be implemented during the next plant outage which is now scheduled to begin September 8, 1977. Until this redesign is implemented, administrative procedures have been implemented to assure that one charging pump will be available for recirculation service. A temporary operating memorandum has been put into effect which provides for operator action to prevent the loss of one charging pump in the event MOV/LCV 1100C loses its 480V power supply during a LOCA.
- As indicated in Reference (2) the standby charging pump is that pump not automatically started by the sequencer and therefore made available for subsequent recirculation service.
-3 Enclosed is a completed Licensee Event Report form designated LER 77-11. If you have any questions concerning this matter please let me know.
incerely Enclosure cc:
Director, Office of Inspection and Enforcement (40 copies)
Director, Office of Management Information & Program Control (3 copies)
.LICENSEE EVENT REPORT LER 77-11 CONTROL BLOCK:
[PLEASE PRINT ALL REQUIRED INFORMATION) 1 6
LICENSEE LICENSE EVENT NAME LICENSE NUMBER TYPE TYPE MEJI cIAl sl1 sil Ilo-Iol-oI ojo 01lol-olol 1- 0i 1 11111 loll 7 89 14 15 25 26 30 31 32 REPORT REPORT CATEGORY TYPE SOURCE DOCKET NUMBER EVENT DATE REPORT DATE 01 CON'T 1
I L 1 01 5 1 0 -I 0 121 01 61 10 1 81 21 41 71 7 10 19 10 111 71 71 7
8 57 58 59 60 61 68 69 74 75 80 EVENT DESCRIPTION IDuring normal operation, a deficiency was discovered in the charging pump circuitry, 7
880 las recently revised by Design Change 77-05, to eliminate undesirable single failure 7
89 8
4 effects.
Design Change 77-05 was intended to remove one charging pump from equipment 8 7
89 80 0 5[automatically started by the sequencer, however postulated loss of power continues to 7 89 8
o afresult in the auto start of both pumps contrary to the intent of DC 77-05. Redesign 7
89 PRIME 80 SYSTEM CAUSE COMPONENT COMPONENT CODE CODE COMPONENT CODE SUPPLIER MANUFACTURER VIOLATION 17Pl?.C 1 -
[IlAILV D IJP 9 L N
7 8 9 10 11 12 17 43 44 47 48 CAUSE DESCRIPTION 0 Deficiency in the charging pump circuitry recently revised to eliminate the automatic 7
89 80 09 starting of both pumps by the sequencers.
1 7
8 9 80 101 8
7 89 8
FACILITY METHOD OF 80 STATUS
% POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION E7 LIE 0
9 9 I
NA I
NA 78 F9 10 12 13 44 45 46 80 FORM OF 8
ACTIVITY COrTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE 7
8 9
10 11 44 45 80 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION 13 lololol I I NA 7
8 9 11 12 13 80 PERSONNEL INJURIES NUMBER DESCRIPTION E410o0l 01 1 NA 1
7 8 9 11 12 60 OFFSITE CONSEQUENCES 15 NA 7
89 LOSS OR DAMAGE TO FACILITY TYPE DESCRIPTION 16 LJ I NA 7
8 9 10 80 PUBLICITY NA 7
89 80 ADDITIONAL FACTORS EM Jof the charging pump control circuitry to eliinate starting of both pumps has been 7
89 80 19g initiated (77-11).
7 89 80 NAME:.
H. L. OttosonPHN:(1)5299 GPO stat--e