ML13330A797
| ML13330A797 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/19/1979 |
| From: | Curran J SOUTHERN CALIFORNIA EDISON CO. |
| To: | |
| References | |
| 79-290, NUDOCS 7911300504 | |
| Download: ML13330A797 (4) | |
Text
REGULATORY NFORMATIUN DISTRIBUTION S EM (RIDS)
ACCESSION NBR:7911300504 DOC,DATE: 79/11/19 NOTARIZED: NO DOCKET #
FACL:50-206bSan Onofre Nuclear Station, Unit 1, Southern Californ 05000206 AUTH.NAME AUTHOR AFFILIATION CURRAN,JM.
Southern California Edison Co.
RECIPNAME RECIPIENT AFFILIATION Region 5, San Francisco, Office of the Director
SUBJECT:
R0:missing U-bolts on piping utilized to transfer diesel fuel from storage tank to day tanks.Two.-day engineering evaluation undertaken to determine pipe operability during earthquakeNew U-bolts will be installed, DISTRIBUTION CODE: A0025 COPIES RECEIVED:LTR ENCL IZE:
TITLE: Incident Reports NU0T E S:.4S!
-?muu.hswsuyam...n.fn...---
RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR EN L ID CODE/NAME LTTR ENCL ACTION:
05 BC "R 4#-
4 INTERNAL:
1 02 NRC PDR 1
T t:2 11 M PA 3
31 14 TA/EDO 1
15 NOVAK/KNIEL 1
1 16 EEB 1
17 AD FOR ENGR 1
1 18 PLANT SYS BR 1
19 I&C SYS BR 1
1 20 AD PLANT SYS 1
22 REAC SAFT BR 1
11 23 ENGR 8R 1
24 KREGER 1
1 25 PWR SYS BR 1
26 AD/SITE ANAL 1
1 27 OPERA LIC BR 1
28 ACDENT ANLYS 1
1 29 AUX SYS BR 1
E JORDAN/IE I
1 HANAUERrS.
1 STS GROUP LEADR I
1 TMI-H STREET 1
EXTERNAL: 03 LPDR 1
04 NSIC 1
29 ACRS 16 1
N RC EQ TOTAL NUMBER OF COPIES REQUIRED: LTTR
-Mr8 ENCL
,Af
Southern California Edison Company P.O. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 RECER7EI NOV 231979 November 19, 1979 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. Engleken, Director Docket No. 50-206 San Onofre Unit 1
Dear Sir:
This letter confirms telephone notifications to your office on November 15 and 16, 1979 of a matter reported in accordance with Section 6.9.2.a(9) of the San Onofre Unit 1 Technical Specifications.
The matter reported was the discovery of missing U-bolts on the piping utilized to transfer diesel fuel from the storage tank to the day tank associated with the diesel generators. These U-bolts are required to assure that the operability of the piping will not be jeopardized during an earthquake as defined in the Final Safety Analysis Report. A summary of information exchanged during these telephone discussions is provided in the paragraphs below.
November 15, 1979 Telephone Notification In accordance with IE Bulletin No. 79-14, a field verification/
inspection was performed on the South Diesel Generator Fuel Storage and Supply System to verify that the seismic analysis input information for the piping conforms to the actual as-built configuration of the piping. As a result of the field verification/inspection, three missing U-bolts were identified on the filter to day tank fill piping, and as required by IE Bulletin No. 79-14, a two day engineering evaluation was undertaken on November 14, 1979 to determine if the operability of the piping might be jeopardized during an earthquake.
An initial engineering judgement indicates that the maximum stress would be above that originally calculated;
- however, the engineering evaluation involving a review of the original seismic stress analysis and the performance of some hand calculations assuming the U-bolts are missing would have to be completed to determine the extent of the n)-113 o
U. S. Nuclear Regulatory Commission November 19, 1979 overstress condition which would occur during an earthquake.
In parallel with the evaluation, efforts are underway to install the U-bolts to conform the piping system to the seismic analysis input information.
At the conclusion of the telephone discussion, the following action items were agreed upon:
- 1. The two day engineering evaluation will be completed as required by IE Bulletin No. 79-14,
- 2. If the evaluation indicates that the piping would be overstressed above allowables, then the diesel generator would have to be declared inoperable, and the appropriate technical specification requirements governing this condition would have to be imple
- mented,
- 3. If the evaluation indicates that without the U-bolts installed, the piping would not be overstressed above allowables, then the results of the evaluation, including the method utilized to perform the hand calculations, would have to be provided in sufficient detail to determine the conservatism of the calculations, and
- 4. Another telephone notification will be made following completion of the two day engineering evaluation (by 4:30 p.m. on November 16, 1979) to discuss the results.
November 16, 1979 Telephone Notification During the telephone discussion, the NRC was advised of the following:
- 1. As a precautionary measure, an expedited field verification/
inspection was performed late last night on similar piping on the North Diesel Generator Fuel Storage and Supply System, and U-bolts (three) in similar locations were identified as missing.
The efforts to install the three missing U-bolts reported during the telephone discussion yesterday as discussed above were expanded to also include these U-bolts.
- 2. Four of the U-bolts, two each on the South and North Diesel Generator Fuel Storage and Supply System piping, have been installed. The third U-bolt on each piping system will be installed by the end of the day. (This was accomplished.)
- 3. The results of the engineering evaluation indicate that (1) with no U-bolts installed the maximum stress would exceed yield strength, and (2) with the two U-bolts installed as discussed in 2 above the maximum stress would be within allowables. While not specifically discussed, the original computer stress analysis indicates that the maximum stress with all three U-bolts installed would be approximately 15,000 psi while with two U-bolts installed the maximum stress would be approximately 21,000 psi (calculated by hand).
It was noted that the hand calculations are currently being checked and independently verified.
U. S. Nuclear Regulatory Commission November 19, 1979
- 4. The installation of all three U-bolts on each piping system will conform the piping system to the seismic analysis input infor mation..
- 5. With the installation of all missing U-bolts on November 16, 1979 as discussed above, it was agreed that the diesel generators do not have to be declared inoperable.
As discussed above, this matter is being reported in accordance -with Section 6.9.2.a(9) of the Technical Specifications. A more detailed report on this matter, together with a completed Licensee Event Report form, will be submitted within two weeks.
Sincerely, J.M.Cra Plant Manager cc:
Director, Office of Inspection and Enforcement Division of Reactor Operations Inspection'