ML061530317
| ML061530317 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/26/2006 |
| From: | Scherer A Southern California Edison Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| EA-03-009 | |
| Download: ML061530317 (6) | |
Text
SOUTHERN CALIFORNIA A. Edward Scherer DISONManager of EDISON' Nuclear Regulatory Affairs An EDISON INTERNATIONAL I Company May 26, 2006 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C., 20555-0001
Subject:
Docket No. 50-361 60-day Post Cycle 14 Refueling Outage Reactor Pressure Vessel Head Inspection Report for San Onofre Nuclear Generating Station, Unit 2
Reference:
First Revised NRC Order EA-03-009, "Issuance of First Revised NRC Order (EA-03-009) Establishing Interim Inspection Requirements for Reactor Pressure Vessel Heads At Pressurized Water Reactors"
Dear Sir or Madam:
This letter provides the Southern California Edison Company (SCE) 60-day post refueling outage response to First Revised NRC Order EA-03-009, "Issuance of First Revised NRC Order (EA-03-009) Establishing Interim Inspection Requirements for Reactor Pressure Vessel Heads At Pressurized Water Reactors" for San Onofre Nuclear Generating Station, Unit 2.
As required by First Revised NRC Order EA-03-009, SCE completed inspections of the reactor pressure vessel head (RPVH) penetrations during the Unit 2 Cycle 14 refueling outage, which ended on April 22, 2006.
In summary, SCE performed a bare metal visual inspection of all 102 RPVH penetrations, a volumetric examination (and supplemental inside diameter surface examination) of all 91 control element drive mechanism (CEDM) nozzles, a wetted surface examination of the vent line penetration, and a volumetric examination of all ten In-Core Instrument (ICI) nozzles. Visual inspections were also performed to identify potential boric acid leaks from pressure-retaining components above the RPV head.
No primary water stress corrosion cracking was identified in any reactor vessel head penetration or attachment weld, no through-wall leakage was identified at any reactor vessel head penetration, and no indication of reactor vessel head degradation was identified during the performance of these inspections at SONGS Unit 2. The SONGS P.O. Box 128 San Clemente, CA 92672 949-368-7501 Fax 949-368-7575
Document Control Desk May 26, 2006 Unit 2 reactor head required no additional corrective actions or root cause evaluations.
Additional details of the specific inspection activities are provided in the Enclosure.
If you have any questions or would like additional information concerning this subject, please call Mr. Jack Rainsberry (949) 368-7420.
Sincerely, Enclosure cc: B. S. Mallett, Regional Administrator, NRC Region IV N. Kalyanam, NRC Project Manager, San Onofre Units 2 and 3 C. C. Osterholtz, NRC Senior Resident Inspector, San Onofre Units 2 and 3
Enclosure 60-day Post Cycle 14 Refueling Outage Reactor Pressure Vessel Head Inspection Report for San Onofre Nuclear Generating Station, Unit 2
60-day Post Cycle 14 Refueling Outage Reactor Pressure Vessel Head Inspection Report for San Onofre Nuclear Generating Station, Unit 2
References:
- 1. First Revised NRC Order EA-03-009, "Issuance of First Revised NRC Order (EA-03-009) Establishing Interim Inspection Requirements for Reactor Pressure Vessel Heads At Pressurized Water Reactors"
- 2. Letter from H. N. Berkow (NRC) to H. B. Ray (SCE) dated June 27, 2005;
Subject:
Relaxation of the Requirements of Order EA-03-009 Regarding Reactor Pressure Vessel Head Inspections, San Onofre Nuclear Generating Station (SONGS), Units 2 and 3 (TAC Nos. MC5522 and MC5523)
- 3. Letter from J. Donohew (NRC) to H. B. Ray (SCE) dated September 26, 2005;
Subject:
San Onofre Nuclear Generating Station (SONGS), Units 2 and 3, Re:
Correction to Relaxation of the Requirements of Order EA-03-009 Regarding Reactor Pressure Vessel Head Inspections (TAC Nos. MC5522 and MC5523)
The following activities were completed for the San Onofre Nuclear Generating Station (SONGS) Unit 2 reactor head during the Cycle 14 refueling outage:
In accordance with part IV.A, SCE calculated the susceptibility category of the SONGS Unit 2 RPVH to PWSCC related degradation, as represented by a value of effective degradation years (EDY) for the end of each operating cycle, using the specified equation. As of the end of the Cycle 13 fuel cycle the calculated value for SONGS Unit 2 was 17.5 EDY.
In accordance with part IV.B, SCE assigned SONGS Unit 2 to the High PWSCC susceptibility category.
In accordance with part IV.C.(1), SCE performed Reactor Pressure Vessel (RPV) head and head penetration nozzle inspections using the techniques of paragraph IV.C.(5)(a) and paragraph IV.C.(5)(b).
In accordance with paragraph IV.C.(5)(a), a bare metal visual examination of no less than 95 percent of the RPV head surface (including 3600 around each RPV head penetration nozzle) was performed. Very minor amounts of surface corrosion were present in some locations with no measurable depth. SCE confirmed that the surface obscured by support structure interferences which are located at RPV head elevations downslope from the outermost RPV head penetration constitute less than 5 percent of the RPV head surface. SCE inspected those areas of the RPV head upslope and downslope from the support structure interferences. The SONGS reactor heads have lift rig structural attachment points at 15 locations evenly spaced around the perimeter.
Each of these support locations has a vertical and a horizontal surface that is obscured from visual inspection. Each obscured surface has dimensions of approximately five Page 1 of 3
60-day Post Cycle 14 Refueling Outage Reactor Pressure Vessel Head Inspection Report for San Onofre Nuclear Generating Station, Unit 2 inches by six inches. There was no evidence of boron or degradation of the reactor head material in these areas.
In accordance with paragraph IV.C.(5)(b), non-visual NDE was performed on each of the 102 penetrations.
The vent line was examined in accordance with method (ii), an ET examination of the entire wetted surface of the J-groove weld and the vent line penetration. The inspection probes for both the weld surface and the vent line penetration surfaces were delivered manually. No indications of PWSCC were identified as a result of this inspection.
All 91 CEDM penetrations were examined in accordance with method (i), UT examinations of the penetration nozzle volume from at least 2 inches above the highest point of the root of the J-groove weld (on a horizontal plane perpendicular to the nozzle axis) to as far down the nozzle as possible. The effective inspection coverages above and below the weld for each nozzle are provided in the CEDM Coverage Table. There were no exceptions to the minimum inspection distances approved for SONGS Unit 2 (References 2 and 3). Supplemental ET surface examinations of the inside diameters of all 91 CEDM penetrations and the OD surface below the weld of CEDM # 87 were performed. No indications of PWSCC were identified as a result of this inspection.
All ten ICI penetrations were examined in accordance with method (i), UT examinations.
The inspection techniques used included: remote UT from the ID surface and remotely delivered UT examinations on the ICI bottom face. Supplemental ET surface examinations of the inside diameters and bottom face surfaces of all 10 ICI penetrations were performed. No indications of PWSCC were identified as a result of this inspection.
In accordance with part IV.D, visual inspections were performed to identify potential boric acid leaks from pressure-retaining components above the RPV head.
In accordance with part IV.E, SCE submits this report within 60 days after returning the plant to operation.
In conclusion, SCE found no evidence of Reactor Vessel Head degradation or boric acid leakage from the reactor coolant pressure boundary during these inspection activities.
Page 2 of 3
60-day Post Cycle 14 Refueling Outage Reactor Pressure Vessel Head Inspection Report for San Onofre Nuclear Generating Station, Unit 2 CEDM Coverage Table Measured Coverame Above and Below CEDM Welds Inspection Coverage Insoection Coveraae Penetration # Above Weld Below Weld Penetration # Above Weld Below Weld Pen 01 3.80 1.28 Pen 46 3.48 1.24 Pen 02 3.60 1.28 Pen 47 3.64 1.00 Pen 03 3.84 1.28 Pen 48 3.52 0.92 Pen 04 3.28 1.24 Pen 49 4.08 1.08 Pen 05 3.80 1.40 Pen 50 3.16 0.96 Pen 06 3.56 1.40 Pen 51 3.36 1.12 Pen 07 3.72 1.32 Pen 52 3.28 1.24 Pen 08 3.32 1.16 Pen 53 3.12 0.92 Pen 09 3.48 1.24 Pen 54 3.60 0.88 Pen 10 3.68 1.28 Pen 55 3.44 0.76 Pen 11 3.32 1.20 Pen 56 3.32 1.00 Pen 12 3.52 1.28 Pen 57 3.92 0.92 Pen 13 3.24 1.32 Pen 58 3.32 0.80 Pen 14 3.52 1.28 Pen 59 3.64 0.84 Pen 15 3.36 1.36 Pen 60 3.28 1.00 Pen 16 3.32 1.32 Pen 61 3.68 1.00 Pen 17 3.40 1.08 Pen 62 3.28 0.96 Pen 18 3.56 1.32 Pen 63 3.36 0.76 Pen 19 3.48 1.20 Pen 64 3.40 0.96 Pen 20 3.32 1.12 Pen 65 3.28 0.80 Pen 21 3.56 1.12 Pen 66 3.68 0.88 Pen 22 3.68 0.96 Pen 67 3.40 0.72 Pen 23 3.56 1.08 Pen 68 3.36 0.88 Pen 24 3.44 1.16 Pen 69 3.76 0.90 Pen 25 3.24 1.08 Pen 70 3.76 1.00 Pen 26 3.48 1.20 Pen 71 3.76 0.80 Pen 27 3.68 0.88 Pen 72 3.80 0.68 Pen 28 3.32 1.24 Pen 73 3.24 0.56 Pen 29 3.84 1.32 Pen 74 3.40 0.88 Pen 30 3.36 1.24 Pen 75 3.52 0.64 Pen 31 3.32 1.16 Pen 76 3.72 0.80 Pen 32 3.36 1.28 Pen 77 3.56 1.00 Pen 33 3.40 1.16 Pen 78 3.72 0.76 Pen 34 3.76 1.16 Pen 79 3.16 0.84 Pen 35 3.32 1.12 Pen 80 3.60 1.04 Pen 36 3.32 1.20 Pen 81 3.64 0.92 Pen 37 3.56 1.16 Pen 82 3.56 0.52 Pen 38 3.52 1.12 Pen 83 3.60 0.56 Pen 39 3.28 0.96 Pen 84 3.40 0.64 Pen 40 3.16 0.92 Pen 85 3.24 0.68 Pen 41 3.60 0.88 Pen 86 3.44 0.94 Pen 42 3.60 1.12 Pen 87 3.68 0.88 Pen 43 3.60 0.92 Pen 88 2.72 0.68 Pen 44 3.68 1.24 Pen 89 2.80 0.80 Pen 45 3.20 1.00 Pen 90 2.52 0.56 Pen 91 2.40 0.60 Page 3 of 3