ML13308B486
| ML13308B486 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 11/15/1976 |
| From: | Arenal A Southern California Edison Co |
| To: | Engelken R NRC/IE, NRC/RGN-V |
| References | |
| NUDOCS 8103060523 | |
| Download: ML13308B486 (6) | |
Text
Southern California Edison Company P 0 BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 9177,0 November 15, 197 2
U. S. Nuclear Regulatory Commission Region V Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Docket No. 50-206 Attention: Mr. R. H. Engelken, Director
Dear Sir:
Reference:
Letter dated November 1, 1976 from SCE (H. L. Ottoson) to NRC Region V, Steam Generator Tube Examination This letter provides the required follow-up information for the referenced letter. Described herein are the results and corrective action to be taken following completion of eddy current examinations conducted on all three steam generators at San Onofre Unit 1. The inspections were accomplished in accordance with guidance provided by our Proposed Technical Specification Change No. 26 submitted to the Commission December 4, 1974.
This letter does not describe and is not concerned with other steam generator inspections (including augmented eddy current testing) or related remedial action dictated by small radius steam generator tube problems. The proposed additional inspection program is described in a letter to the Director of Nuclear Reactor Regulation (from Mr. K. P. Baskin) dated November 2, 1976, a copy of which was forwarded to your office for information.
There are 3,794 tubes in each steam generator. The eddy current program included inspecting, through the U-bend, 692 tubes (17%) in A" steam generator, 755 tubes (20%) in "B" steam generator and 438 tubes (12%)
in "C" steam generator. During these inspections indications of possible defects were noted in each of the steam generators, and additional tubes were inspected. One-hundred and fifty additional tubes were inspected in "A" steam generator for a total of 742 tubes (20%).
Two-hundred additional tubes were inspected in "B" steam generator for a total of 955 tubes (25%), and 140 additional tubes were inspected in "C" steam generator for a total of 578 tubes (15%). No defects were found while inspecting these additional tubes and the areas of the tube bundle containing defective tubes have been defined.
c' r005 aB
-2 The results of the eddy current inspections indicate that there is 50% or greater wall thinning in some tubes of each steam generator. "A" steam generator has 15 tubes with indications of 50% or greater; 3 of these tubes have indications in the area of the antivibration bars and 12 of these tubes have indications two inches above the tube sheet. "B" steam generator has 11 tubes with indications of 50% or greater, all of which are in the area of the antivibration bars. "C" steam generator has 38 tubes with indications of 50% or greater, all of which are in the area of the antivibration bars. These tubes will be plugged before the plant is returned to service.
Sincerely, ORIGINAL SIGNED (A. Arenal)
DEM/JCS:gl3b
Attachment:
Licensee Event Report cc: Director, NRC Office of Inspection and Enforcement Director, NRC Office of Management Information and Program Control bcc: Each NARC Member Each OSRC Member J. T. Head E. J. Bresnahan R. D. Britt J. A. Beoletto D.E.Nunn D. R. Pigott (Chickering & Gregory)
All, individuals who review and initial or sign this letter EDM FILE
CyC Southern ifor.
pany 2244 T G.ROVEF AV PK U. S. Nuclear Regulatory Commission Region V Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Docket No. 50-206 Attention: Mr. R. H. Engelken, Director
Dear Sir:
Reference:
Letter dated November 1, 1976 from SCE (H. L. Ottoson) to NRC Region V, Steam Generator Tube Examination This letter provides the required follow-up information for the referenced letter. Described herein are the results and corrective action to be taken following completion of eddy current examinations conducted on all three steam generators at San Onofre Unit 1. The inspections were accomplished in accordance with guidance provided by our Proposed Technical Specification Change No. 26 submitted to the Commission December 4, 1974.
This letter does not describe and is not concerned with other steam generator inspections (including augmented eddy current testing) or related remedial action dictated by small radius steam generator tube problems. The proposed additional inspection program is described in a letter to the Director of Nuclear Reactor Regulation (from Mr. K. P. Baskin) dated November 2, 1976, a copy of which was forwarded to your office for information.
There are 3,794 tubes in each steam generator. The eddy current program included inspecting, through the U-bend, 692 tubes (17%) in "A" steam generator, 755 tubes (20%) in "B" steam generator and 438 tubes (12%) in "C" steam generator. During these inspections indications of possible defects were noted in each of the steam generators, and additional tubes were inspected. One-hundred and fifty additional tubes were inspected in "A" steam generator for a total of 742 tubes (20%).
Two-hundred additional tubes were inspected in "B" steam generator for a total of 955 tubes (25%), and 140 additional tubes were inspected in "C" steam generator for a total of 578 tubes (15%). No defects were found while inspecting these additional tubes and the areas of the tube bundle containing defective tubes have been defined.
11
-2 The results of the eddy current inspections indicate that there is 50% or greater wall thinning in some tubes of each steam generator. "A" steam generator has 15 tubes with indications of 50% or greater; 3 of these tubes have indications in the area of the antivibration bars and 12 of these tubes have indications two inches above the tube sheet. "B" steam generator has 11 tubes with indications of 50% or greater, all of which are in the area of the antivibration bars. "C" steam generator has 38 tubes with indications of 50% or greater, all of which are in the area of the antivibration bars. These tubes will be plugged before the plant is returned to service.
Sincerely, ORIGINAL SIGNED (A. Arenal)
DEM/JCS:gl3b
Attachment:
Licensee Event Report cc: Director, NRC Office of Inspection and Enforcement Director, NRC Office of Management Information and Program Control bcc: Each NARC Member Each OSRC Member J. T. Head E. J. Bresnahan R. D. Britt J. A. Beoletto D. E. Nunn D. R. Pigott (Chickering & Gregory)
All.individuals who review and initial or sign this letter EDM FILE
UCENSEE EVENT REPORT CONTROL BLOCK:
(pA an" 0g "u mun LICENSEE NAME LICENSE NUMBER LIENPE EVENT NAMETYPE TYPt CI ASL10 1-.5 11 1 01 0 0l-10 o 10 10 -
010 j 4 1 1 1 1t0 1 1 7 0 14 15 25 26 3
a REPORT REPORT CATEGORY TYPE SOURCE DOCKET NUMBER TEVENT DATE CON'T P
P)
L 10 15 1 01 -j 1 1 011 716
- 11.
2 57 58 59 60 61 58 69 74 75 s0 EVENT DESCRIPTION Eddy current examinations of the steam generator 7
8 9 as0 STubes inica te there are 15 tubes in A steam generator, 11 tubes in B steam w
7 89 s
f0R [ generator and 38 tubes in C steam generator that have greater than 50% tube e
EN L wall thinning.Licensee Event Report No. 76-8 7 8 9 7
98.9 PRIME SYSTEM CAUSE COMPONENT COMPONENT CODE CODE COMPONENT CODE SUPPLER MANUFACTURER VIOLATION 10D L C.j [..
IH ITIEIXI C HI II IWI l20 I
N 7
8 9 10 11 12 17 43 44 47 CAUSE DESCRIPTION fEIWestinghouse Steam-Generators, Model 27, Tuetinng at the anti-vibrainbr
_Tube thinnin atteat-iration bars Eg L and two inches above the tube sheet. All tubes with greater than 50% thinning, 7 89 10 LIndicatIon will be plugged.
7 88(
FACILITY METHOD OF 80 STATUS '
POWER OTHER STATUS DISCOVERY DISCOVERY OESCRIPTION 7 8
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0 01 01 N A 4
B I L Eddy current testing of S/Gs 798 9
10a.
12 13 44 45 45 FORM OF 80 ACTIVITY CONTENT A
0 OF RELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE Z
uz IA
.1INA 7 8
.9 10 11 44 45 PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION
[
1o lolo (I
l NA 7
e 9 11 12 13 PERSONNEL INJURIES.
NUMBER DESCRIPTION 8 19 I010 I
N/A 7
8 9 11 12 OFFSITE CONSEQUENCES N/A LOSS OR DAMAGE TO FACILITY TYPE DESCRIPTION
[B
- z. J I 7
8 9 10 PUBLICITY 7
89 ADDITIONAL FACTORS 7 es s
E9 I N/A 7 89 NAME:
H.L. Ottoson PHO NE:
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