ML20040C071
| ML20040C071 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 02/02/1977 |
| From: | Burger A Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A635 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8201270231 | |
| Download: ML20040C071 (3) | |
Text
.
e.
UN TED STATEE
[*,.
71 NUCLEAR REGULATORY COMMISclOf
{,
s w p f{, f WASHINGTON D. C. 20555
\\..v Februarv 2,1977 DOCKET N0. 50-206 LICENSEE:
SOUTHERN CALIFORNIA EDISON COMPANY (SCEC)
FACILITY: SAN ON0FRE, UNIT N0. 1
SUMMARY
OF MEETING HELD ON JANUARY 18, 1977, TO DISCUSS MATTERS CONCERNING THE SAN ON0FRE, UNIT NO.1 STEAM GENERATORS.
On January 18, 1977, representatives of Southern California Edison Company and its consultant, Westinghouse, met with the NRC staff on matters con-cerning the recent inspection of steam generators and steam generator repairs to be comple Md prior to plant startup during February 1977.
A list of attendees is attached.
Significant highlights of the meeting are sumarized below.
The licensee presented the methods and results of steam generator inspections to determine if any tubes in the steam generator had experienced dentin; and subsequent flow slot"hourglassing". The licensee also presented details on the antivibration bar degradation found during examinations of the tube bend regions in the steam generators and proposed corrective actions.
The steam generator tube inspection program included handhole entry inspections of all steam generators (units A, B and C), upper bundle entry in steam generator A, eddycurrent crobino inspecticns of tubing in all steam generators, and drilling of a three inch hole in steam generator C for entry to photograph and gage flow slots in the steam generator tuce support plates.
The licensee pointed out that the results of these inspections, including the thorough examinations of all steam generator support plates, particularly the examinations of the upper support plates, showed t. hat the flow slots are close to the as-built condition, therefore confinning the absence of "hourglassing".
Based on these findings, the licensee has l
concluded that no tube plugging program is required and, since a change of the flowslot geometry is not anticipated, an inspection prior to the next refueling is not needed.
However, the licensee has proposed to carry out an l
inspection program during the next refueling (Cycle VII) consisting cf:
- 1) photographing flow slots in upper ' support plates in steam generators A and B through handhole entry, 2) eddy current probing inspection of all tubes in rows 1 through 5 around U-bends in all steam generators, and 3) Photographing i
and measuring flow slots in the upper support plate through the 3 inch access opening in steam generator C.
The licensee presented the results of inspections of the tube bend regions in all steam generators which revealed fretting of th'e antivibration bars.
UDELL81-313 PDR Document 6
e Meeting Summary for February 2,1977 Southern California Edison Co.
Two antivibration bars were removed for examination. They showed sig-nificant thinning (from 1/4 inch to 1/16 incn at some areas of centact with tubes) due to fretting. The licensee described the corrective action whien involves installation of 134 new antivibration bars in each steam generator by sliding them over the existing antivibration bars which will remain in place.
The new bars will be of improved design, namely, rectangular instead of round cross section and made of Inconel 600 instead of carbon steel.
The licensee has performed analyses to confirm that the new bars will provide adequate support and that potential vibration of the remaining old antivibration bars will be insignificant.
The licensee has also plugged those tubes supported by the new antivibration bars which showed eddycurrent indications equal or greater than 50 percent. Those affected tubes that are not supported by the new antivibration bars with indications even smaller than 20 percent have been plugged also.
In addition, the licensee has proposed an inspection program during the next refueling outage involving eddycurrent probing of all tubes in the critical rows in the areas of the antivibration bars.
At the conclusion of the meeting the licensee committed to submit within two weeks a final report on the subjects presented during the meetino,
~'
%7 ev p
A. Burger, Project Manager Operating Reactors Branch #1 Division of Operating Reactors
Enclosure:
Attendance List I
D -
g ATTENDANCE LIST "f ETING WITH SOUTHERN CALIFORNIA EDISON COMPANY JANUARY 18. 1977 NRC STAFF JL Burger B. D. Liaw F. Almeter L. Shao R. Stuart
.W. J. Collins SOUTHERN CALIFORNIA EDISON COMPANY V. G. Haynes R. W. Krieger SAN DIEGO GAS & ELECTRIC COMPANY W. Griffith WESTINGHOUSE P. G. Smith, Tampa Division D. C. Marburger, Nuclear Safety A. W. Klein, PWRSD, Materials D. D. Malinowski, PWRSD,- Engineering -
R. S. Grimm, Jr., NSD BNL J. R. Weeks 4
)s A CZ:0,-
Steam Generator Tabe Insrectiens January 18. 1977 1.
Introductica II.
Discu:: ion of P.esuits of Small Radius Steca Generator Tube Inspection Progr =
A.
Handhole Entry Inscettions B.
Upper Sundle Entry In;necticns C.
Eddy Current Probing Insoections D.
3 Inch Port Inspectient E.
Centribution of Results Toward the Accomplishment of
~ Principal Objectives of Integrated Inspection Program III.
Discussion of Safety Aspects Relative to Lower Support Plate Flow Slot Daformation (Hourg'assing)
IV..' Discussicn of Steam Generator Tubes and Antivibration Bars in U-Bend Area A.
Inspection Findings and Anti tibrction Bar Installation B.
Examination of Removed Antivibration Bar. and Tube Samples to '
Determine Degradation liechanism C.
Safety Aspects of Antivibration Bar Installation V.
Discussion of Pro' gram of Corrective Actions A.
Upper Support Plate Flow Slot Deformation B.
Lower Support Plate Flow Slot Deformation C.
Steam Cenerator Tubes and Antivibration Bars in U-Bend Area 7t"-
9 d
.e k
e 6
o 6
we e
=
em. g m e
, - ~ -, - - - - -
y,
,, -.-