ML13330B283
| ML13330B283 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/29/1988 |
| From: | Medford M SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TAC-67463, NUDOCS 8803310226 | |
| Download: ML13330B283 (4) | |
Text
Southem California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 M. 0. MEDFORD TELEPHONE MANAGER OF NUCLEAR ENGINEERING (818) 302-1749 AND LICENSING March 29, 1988 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Steam Generator Inspection Information San Onofre Nuclear Generating Station Unit 1
References:
- 1. Letter, M. 0. Medford, SCE, to U. S. Nuclear Regulatory Commission, Revision to Proposed Change No. 182, March 22, 1988
- 2. Letter, M. 0. Medford, SCE, to U. S. Nuclear Regulatory Commission, Steam Generator Inspections, March 25, 1988 Reference 1 provided the NRC with a revision to Proposed Change No. 182, relating to the inspection and repair of the San Onofre Nuclear Generating Station, Unit 1 (SONGS 1) steam generators. In response to NRC Staff questions in the area of the coefficient of friction used in the supporting analyses, a reference to the ASME BP&V Code, and data relating to the tubes to which the modified tube plugging limit has been applied, the following information is provided.
Provided as an enclosure is a report of all those tubes in service which have defects below the uppermost inch of sound tube roll expansion. This report also satisfies the requirement of Proposed Change No. 182, as noted in Reference 2, to report these results for NRC review. It is noted that Reference 2 reported that 44 tubes at SONGS 1 remain in service with flaws below the uppermost inch of tube roll expansion. A final review of the data revealed that 46 tubes remain in service in this condition. As stated above, the data for these tubes is provided as an enclosure to this letter. The final breakdown is 2, 2, and 42 tubes in steam generators A, B and C, respectively. It is noted the results of these inspections conclude that, consistent with information presented in References 1 and 2, the SONGS 1 indications in the region of the tube roll expansion are axial in nature.
880O3310226 SS3OS29 PDR ADOCK 05000206 P
DCD J
L-i
Document Control Desk March 29, 1988 The coefficient of friction between the tube and tubesheet material used in the analyses reported in Reference 1 was stated to be conservative. The conservatism results from the use of a coefficient that is one half that which is appropriate for the materials in the tube to tubesheet joint. This is the same that was determined for and used in similar calculations for the Connecticut Yankee-Haddam Neck Plant.
Additionally, it was requested that SCE provide a specific reference for the factors of safety that were obtained from Section III of ASME BP&V Code.
Responsive to that request, the referenced factors of safety were taken from "Criteria of the ASME Boiler and Pressure Vessel Code For Design By Analysis in Sections III and VIII, Division 2", Copyright 1969, ASME, page 9.
If you have any additional questions, please let me know.
Very truly yours, Enclosure cc: J. B. Martin, Regional Administrator, NRC Region V F. R. Huey, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3
SONGS 1 Steam Generator Tubes In Service with Defects Below the Uppermost Inch of Tube Roll Expansion Steam Tube Identification Degradation Generator Row Column Location(a)
Size(b)
A 4
3 1.50 94 29 16 1.20 46 B
35 31 1.20 DRI(c) 36 83 2.00 DRI(c)
C 6
1 1.30 90 7
1 1.20 98 6
2 1.30 84 7
2 1.30 90 4
3 1.30 90 6
3 1.20 54 7
3 1.40 75 4
4 1.20 95 6
4 1.20 78 6
5 1.20 75 6
6 1.20 82 7
6 1.20 67 15 6
1.40 95 2
7 1.20 67 6
7 1.20 67 12 7
1.10 67 6
8 1.00 86 12 8
1.00 95 6
9 1.00 84 30 13 1.60 59 29 16 1.10 DRI(c) 25 17 1.00 79 34 17 1.30 65 25 18 1.10 87 28 18 1.00 90 37 18 1.10 77 1
20 1.10 61 41 34 1.10 61 41 35 1.10 76 39 37 1.10 98 40 38 1.20(d) 40 47 48 1.20 58 47 49 1.20 49 38 63 1.20 64 47 63 1.30 52 39 71 1.10 55
SONGS 1 Steam Generator Tubes In Service with-Defects Below the Uppermost Inch of Tube Roll Expansion (continued)
Steam Tube Identification Degradation Generator Row Column Locationia)
Size(b)
C 1
75 1.10 67 36 81 1.30 75 29 84 1.30 75 29 85 1.00 72 24 87 1.20 91 25 87 1.30 80 Notes: (a) Distance to flaw, below the top of the sound roll as measured by the standard bobbin probe examination. All flaws were verified to be below the uppermost one inch of sound roll by use of the F*
probe (regardless of the bobbin coil distance called).
(b) Percent through wall degradation as called from the standard bobbin probe examination.
(c) Distorted Roll with an Indication - The bobbin probe could not quantify depth, but the MRPC probe confirmed presence of a flaw.
(d) The distance called from the bobbin probe was 0.70 inches.
However, the rotating pancake coil corrected this distance to 1.20 inches and the F* probe confirmed that the indication was below the uppermost inch of sound roll.
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