ML20040C078
| ML20040C078 | |
| Person / Time | |
|---|---|
| Site: | Surry, Turkey Point, San Onofre  |
| Issue date: | 02/01/1977 |
| From: | Head J SOUTHERN CALIFORNIA EDISON CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A635 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8201270240 | |
| Download: ML20040C078 (3) | |
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Director of Nuclear Reactor Regulation J
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Mr. A. Schwencer, Chief Il t,lf'// /J Ct Operating Reactors Branch #1 IEB 9 Division of Operating Reactors
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Gentlemen:
Subject:
Docket No. 50-206, Provisional '
4 Operating License No. DPR-13 Steam Generator Inspections San Onofre Nuclear Generating Station, Unit-1 s
By letter dated November 2,1976, we provided the NRC with our specific steam generator tube inspection program to investigate the possible existence in San Onofre Unit 1 of conditions believed to have led to a steam generator tube failure at Virginia Electric and Power Company's Surry Unit No. 2.
That inspection program included (1) handhole' entry inspections, (2) upper bundle entry inspection, and (3) eddy current probing inspections.
The purpose of the inspection program was to as_ cert.ain the condition of'the.
flows _ lots'in the upper tube _ support plates in afl.threTe ~.(31 steam
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e,enerators.
Subsequent to submittal of the November 2, 1973" letter, it was also determined that a three (3) inch access opening at the upper tube support plate would be dri11ed in Steam Generator _"C".
for observation.and measurement of the flowslots 'in the upper tube support plate.
This program of inspections has been completed.
In addition to completing the program of inspections
' discussed above, the following conditions were also thorough.lv investiaated and evaluated, and where required corrective actions sere completed.
1)
Support plate deformation and flowslot "hontginssing" in the bottom two (2) tube support plates in Steam Generators "A" and "C",
only, and 2)
Increases in tube wall degradation at the antivibratiot, bars (AVB) and thinning of the AVB's themselves in all three (3) steam generators.
e201270240 810925 Document 8 PDR FOIA UDELL81-313 PDR
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of the evclant:Or. c: the cansit:en: c : r c u r.= e: aseve were presente.
to members of your staff at a meeting in Let hesda, Maryland on January 18, 1977.
As indicated at that meeting, the report contain-ing the 2nformation presented to your staff has been prepared and is entitled. " Steam Generator Inspections, San Onofre Nuclear Generating Station, Unit 1, January 30, 1977,"one (1) copy of which accompanies this latter.
Nineteen (19) additional copies of the report will be forwarded by February 7, 1977 following reproduction.
Based on the inspections and evaluation discussed in the report, San Onofre Unit 1 operations can be resumed following the current refueling / maintenance outage without compromise to the safety or an_incr. case in the risk associated witn the operation of the steam generators.
The program of inspections indicate that there is no evidence in the San Onofre. Unit _1 steam generators of the conditions that resulted in the failure of a steam generator tube at Surry Unit No.
2.
Accordingly, neither a program of preventative tube plugging nor an interim shutdown for reinspec11on prior to the inspection planned at the next refueling outage are warranted.
The evaluations of the lower. tube supp' ort plate deformation and flowslot "hourglassing" indicate that there are no safety. consequences with regard to steam generator lowe_r tube suonort nlate deformation and
,'11gament cracking.
Theretcrc, impicment'a tion ci a program of l
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correcitive actions is also not warranted.
However, based on the evaluation of tube and AVB degradation, new AVB's have been installed to arrest further tube and AVB degradation due to excessive vibration
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damage.
In addition,' tube plugging in accordance with the criteria established in Section 4.3 of the enclosed report is required.
An interim shutdown for reinspection prior to the ' inspection planned at the next refueling outage, however, is not warranted.
The San Onofre Unit 1 Safety Review Committees have. reviewed these corrective actions.
As required by our letter dated December 1, 1976 to Recion V, Office
'of in soection_and En forcement, the information contained in Section 4 of the enclosed report also provides the pertinent details of the new AVB installation.
In accordance with your letter dated October z9, 1976, it is respectfully requested that you approve, based on the program of corrective actions which have been completed as discussed in Section 43 of the enclosed report, resumption of power operation at San Onofre
" Unit 1.
It is our desire that your written approval be received promptly, but in no case, later than February 22, 1977, when it is expected that reactor coolant system heatup will commence.
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Lizeeror o_ ::uclear Reactor Regulation
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If you have any questions or desire further information concerning the enclosed report, please contact me.
Very truly yours, c
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Enclosure cc:
Jack B. Moore R. H. Engelken (Director, OIE, Region V) 9 o
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