ML053470475
| ML053470475 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/12/2005 |
| From: | Hartz L Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 05-741 | |
| Download: ML053470475 (16) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY
- RICHMOND, VIRGINIA 23261 December 12, 2005 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Serial No.05-741 NLOS/GDM RO Docket No.
50-281 License No.
DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT 2 ASME SECTION XI INSERVICE INSPECTION PROGRAM PARTIAL EXAMINATION RELIEF REQUESTS FOR THE THIRD TEN YEAR REACTOR VESSEL EXAMINATIONS Virginia Electric and Power Company performed inservice inspection (ISI) examinations at Surry Power Station Unit 2 for the third ten-year IS1 interval to the requirements of the 1989 Edition of ASME Section XI. Examinations were performed on the Surry Unit 2 reactor vessel during the spring 2005 refueling outage. Certain examinations were only partially performed, i.e., less than 90% weld coverage achieved, due to physical interferences that prohibited attaining full weld coverage.
Pursuant to 10 CFR 50.55a(g)(6)(i), relief is requested from certain requirements of the ASME Section XI Code associated with examinations where only partial weld coverage could be obtained. Relief Requests PRT-01 and PRT-02 are included in Attachments 1 and 2, respectively, and provide the basis for this request. The Station Nuclear Safety and Operating Committee has approved the relief requests.
Similar relief was requested for Surry Unit 1 in a letter dated April 11, 2005 (Serial No. 05-1 81).
If you have any questions or require additional information regarding the attached relief requests, please contact Mr. Gary D. Miller at (804) 273-2771.
Very truly yours, DV67-Leslie N. Hartz Vice President - Nuclear Engineering Attachments Commitments made in this letter: None
Serial No.05-741 Docket No. 50-281 Page 2 cc:
U. S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 237185 Atlanta, Georgia 30303 Mr. S. R. Monarque U. S. Nuclear Regulatory Commission One White Flint North 11 555 Rockville Pike Mail Stop 8H12 Rockville, MD 20852 Mr. N. P. Garrett NRC Senior Resident Inspector Surry Power Station Mr. R. A. Smith Authorized Nuclear Inspector Surry Power Station
Serial No.05-741 Docket No. 50-281 Relief Request PRT-01 Virginia Electric and Power Company (Dominion)
Surry Power Station Unit 2
Serial No.05-741 Docket No. 50-281 I.
II.
Ill.
Virainia Electric & Power ComDanv Surrv Power Station Unit 2 Third Ten Year Interval Relief Reauest No. PRT-01 Identification of Component Weld No.
1-01 Drawing 11 548-WMKS-RC-R-1.I ASMEClass 1
Description Reactor Vessel Shell-to-Flange Weld Code Requirement The 1989 Edition of ASME Section XI Table IWB-2500-1, examination category B-A, item number B1.30, requires volumetric examination of the reactor vessel shell-to-flange weld.
The volume to be examined includes the weld plus 1/2t (t = thickness) of base material on each side of the weld for essentially 100% of the weld length. The subject examination volume is required to be examined in four directions; two opposing perpendicular and two opposing parallel beam directions in relationship to the weld axis.
Basis for Relief The ultrasonic examination of the reactor vessel shell-to-flange weld was performed using a combination of manual and remote automated ultrasonic examination techniques. The manual examination was applied from the flange surface with techniques in accordance with the requirements of ASME Section V, Article 4. The remote automated ultrasonic examinations were performed from the vessel shell inside surface using techniques qualified by demonstration for Appendix VI I I, Supplements 4 and 6 of the 1995-96 Addenda of ASME Section XI, as allowed by NRC approved relief request SR-035. (Reference NRC letter to Virginia Electric and Power Company dated December 8, 2004.) These automated techniques are noted to produce more accurate, reliable and repeatable procedures of examinations than the standard Section V techniques previously used.
Figure 1 shows the reactor vessel and associated welds. Figures 2 and 3 illustrate the weld profile and show scan orientation and directions.
Coverage of the 1
Serial No.05-741 Docket No. 50-281 examination volume is obtained by combining the manual examination performed from the flange surface (Figure 2) with the automated coverage obtained from the vessel shell surface (Figure 3). The examination performed from the flange surface provides examination coverage with the ultrasonic sound beam directed essentially normal to the weld axis.
Coverage from the flange provides coverage of the examination volume in one beam direction, perpendicular to the weld axis. The ASME Section XI, Appendix VIII, Supplements 4 and 6 techniques are applied from the vessel inside surface, scanning in four directions to the extent possible. Due to the surface geometry of the flange, the ability to scan the necessary areas to provide complete coverage of the examination volume in four directions is limited.
Specifically, the examination tool end effector, which holds the ultrasonic transducers, is not able to maintain the necessary surface contact on the non-parallel surface of the flange taper located just above the weld. The area most affected by this surface geometry limitation is the 1/2t base material volume above the weld. The total examination coverage obtained for the weld volume was 97.6%.
Table 1 provides the breakdown of coverage of the required examination volume.
The overall coverage of the entire required examination volume using the combined techniques is 85.1 YO.
IV. Alternative Examination As part of the requirement of Table IWB-2500-1, Category B-P, Item B15.10, a visual VT-2 inspection is conducted on the reactor vessel every refueling outage to detect evidence of through wall leakage on the vessel. This examination has been performed in conjunction with approved Relief Request RR-008, which addresses visual inspection of the bottom of the reactor vessel for the Third Inspection Interval.
Similar inspection will continue in the Fourth Inspection Interval by approved Relief Request SPT-003, Revision 1. The weld in question has been examined to the greatest extent achievable with greater reliability and accuracy than in previous intervals.
Furthermore, Surry's Technical Specifications include surveillance requirements that monitor for reactor coolant system leakage and radiation levels in containment. Consequently, based on: 1) VT-2 visual examination of the bottom of the reactor vessel performed every refueling outage, 2) limited volumetric examination coverage revealing no indications, and 3) TS required RCS leakage and containment radiation monitoring, appropriate actions have been taken and adequate monitoring is in place for detecting through-wall leakage.
Therefore, Dominion requests relief from performing the code required volumetric examination on the inacessible portion of the Surry Unit 2 reactor vessel shell-to-flange weld in accordance with 10 CFR 50.55a(g)(6)(i) since examination in this area is impractical.
2
Serial No.05-741 Docket No. 50-281
' THICK A S S 2 SEE NOTE 2 GENERAL ELEVATION Figure 1 Reactor Vessel
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Serial No.05-741 Docket No. 50-281 Beam Direction ccw cw UP DOWN^
Table 1 Surry Unit 2 Reactor Vessel Flange to Upper Shell Weld 1-01 Coverage Percentages Examination Volume Coverage' Weld Volume Weld Volume Weld Volume 100 53.5 100 53.5 100 53.5 100 53.5 100 53.5 100 53.5 100 100 71.6 52.5 100 100 100 100 100 100 100 99 45 degree L 45 degree L 45 degree Dual Single Shear Note': The examination volume coverage calculations are broken down into coverage of the weld volume (Weld) and the 1 /2t base material volume (Volume) for each examination transducer and beam direction.
Note2: The coverage in the down direction is the total coverage obtained combining the examination techniques from the flange face and the vessel ID surface.
Note: The examination volume coverage is calculated by averaging the combined coverage obtained in each of the required examination beam directions with each of the qualified transducers.
Scans Parallel to the Weld Axis - CCW/CW Scans Perpendicular to the Weld Axis - UP/DN Examination Coverage = 85.1 YO
Serial No.05-741 Docket No. 50-281 Relief Request PRT-02 Virginia Electric and Power Company (Dominion)
Surry Power Station Unit 2
Serial No.05-741 Docket No. 50-281 Virainia Electric & Power Companv Surrv Power Station Unit 2 Third Ten Year Interval Relief Reauest No. PRT-02 I. Identification of Component Weld No.
1-04 Drawing 11 548-WMKS-RC-R-1.I ASMEClass 1
Description Reactor Vessel Circumferential Shell Weld
- 11. Code Requirement The 1989 Edition of ASME Section XI Table IWB-2500-1, examination category B-A, item number B1.11, requires volumetric examination of the reactor vessel circumferential shell weld. The volume to be examined includes the weld plus 1/2t (t = thickness) of base material on each side of the weld for essentially 100% of the weld length. The examination volume is addressed in two regions to provide the necessary coverage with qualified examination techniques. The clad to base metal interface, including 15% t of the vessel wall (measured from the clad to base metal interface) and the remaining 85% of the vessel thickness. The clad to base metal interface region shall be examined from four orthogonal directions using procedures and personnel qualified in accordance with Supplement 4 of Appendix VIII. The remaining 85% of the vessel thickness shall be examined from four orthogonal directions (when possible) using procedures and personnel qualified in accordance with Supplement 6 to Appendix VIII.
When access restricts coverage in four directions, coverage of the remaining 85% of the examination volume is considered fully examined if coverage is obtained in one parallel and one perpendicular direction using a procedure and personnel qualified for single-side examination in accordance with Supplement 6.
Ill. Basis for Relief The ultrasonic examination of the reactor pressure vessel circumferential shell weld is conducted in accordance with techniques qualified by demonstration for Appendix VIII, Supplements 4 and 6 of the 1995-96 Addenda of ASME Section XI.
1
Serial No.05-741 Docket No. 50-281 There are four core support lugs located at the 0-degree, 90-degree, 180-degree, and 270-degree positions of the vessel inside surface just above the weld, which restrict complete coverage of the required examination volume. The ultrasonic examination of this weld was performed by scanning the accessible scan surfaces between the support lugs and below the support lugs. Figure 1 shows the general configuration of the reactor vessel and location of weld 1-04. Figures 2 and 3 show the ultrasonic scanning boundaries for this weld with the restrictions due to the core support lugs. The size of the ultrasonic manipulator end effector limits how close the individual transducers can be positioned to the support lugs while scanning.
The proximity of the end effector to the support lugs limits the amount of coverage obtained with each of the qualified transducers. Table 1 provides the breakdown of percent coverage of the required examination volume by scan direction and transducer. The achieved coverage of the required examination volume applying the qualified techniques is 76.3%.
IV.
Alternative Examination As part of the requirement of Table IWB-2500-1, Category B-P, Item B15.10, a visual VT-2 inspection is conducted on the reactor vessel every refueling outage to detect evidence of through wall leakage on the vessel. This examination has been performed in conjunction with approved Relief Request RR-008, which addresses visual inspection of the bottom of the reactor vessel for the Third Inspection Interval.
Similar inspection will continue in the Fourth Inspection Interval by approved Relief Request SPT-003, Revision 1. The weld in question has been examined to the greatest extent achievable with greater reliability and accuracy than in previous intervals.
Furthermore, Surrys Technical Specifications include surveillance requirements that monitor for reactor coolant system (RCS) leakage and radiation levels in containment. Consequently, based on: 1) VT-2 visual examination of the bottom of the reactor vessel performed every refueling outage, 2) limited volumetric examination coverage revealing no indications, and 3) TS required RCS leakage and containment radiation monitoring, appropriate actions have been taken and adequate monitoring is in place for detecting through-wall leakage.
Therefore, Dominion requests relief from performing the code required volumetric examination on the inacessible portion of the Surry Unit 2 reactor vessel circumferential shell weld in accordance with 10 CFR 50.55a(g)(6)(i) since examination in this area is impractical.
2
Serial No.05-741 Docket No. 50-281 UPPER SHELL CLASS 2 ASTM-A-506.9.64' THICK REACTOR VESSEL LOWER SHELL ASTM-A-533.9.0' THICK BOTTOM SHELL ASTM A-508 CLASS 2 5.375' THICK INTERIOR OTTACHMENTS OUTSIDE BELTLINE REGION 3/4TNSTRUMENT NOZZLES (TYPICAL 50 PLACES1 SEE NOTE 2 GENERAL ELEVATION Figure 1 Reactor Vessel
Serial No.05-741 Docket No. 50-281 ANGULAR SCANNING BOUNDARY BETWEEN CORE SUPPORT LUGS I
PERP SCANS 1 - 323,77 TOP PERP I - 325.41 TOP PARALLEL I
BETWEEN 0' AND 90' BETWEEN 90' AND 180' BETWEEN 180' AND 270' BETWEEN 270' AND 0 7.25' - 82.75' 97.25' - 172.75' 187.25' - 262.75' 277.25' - 352.75' I
79.78' BOTT PERP I-79' BUTT PARALLEL PARALLEL SCANS
\\
BETWEEN 0' AND 90' BETWEEN 90' AND 180' BETWEEN 180' AND 270' BETWEEN 270' AND 0' 8.5' - 81.5' 98.5' - 171,5' 188.5' - 261.5' 278.5' - 351.5' NOTES1 1) PERP SCANS MAY BE COMBINED WITH LOWER HEAD CIRC WELD PERP SCANS PROVIDING ALL BOUNDARIES ARE MET AND SCANS BETWEEN THE LUGS OVERLAP,
- 2) EXAMINER AND TOOL OPERATOR TO INSURE THAT SCANS UNDER THE LUGS WELD 1-04 INCREMENT SIZE1 Figure 2 PARALLEL - 0.5' PERP 0.365'
Serial No.05-741 Docket No. 50-281 f
332.31 L
82' TOP PARALLEL 79.3' TOP PERP 79' BOTT PARALLEL ANGULAR SCANNING BOUNDARY UNDER CORE LUGS PERP SCANS UNDER 0" LUG 352.75' - 72.5' UNDER 04 LUG 351.5' - 8.5' UNDER 90' LUG UNDER 180" LUG 82.75' - 97.25' 172,75' - 187,25' PARALLEL SCANS UNDER 90. LUG UNDER 180" LUG 81.5' - 90.54 171.5' - 188,S' UNDER 270' LUG 262.75' - 277.25' UNDER 270' LUG 261,s' - 278,s' NOTES'
- 1) PERP EXAM STRATEGY UNDER THE LUGS IS TO MAXIMIZE COVERAGE WITH THE 45' FRONT FACING EXTRA PROBE.
- 2) EXAMINER AND TOOL OPERATOR TO INSURE THAT SCANS UNDER THE LUGS AN1
- 3) PERP SCANS MAYBE COMBINED WITH LOWER HEAD CIRC WELD PERP SCANS SCANS.BETWEEN THE LUGS OVERLAP, PROVIDING ALL BOUNDARIES ARE MET.
PARALLEL - 0.5' PERP - 0.365' WELD 1-04 Figure 3
Serial No.05-741 Docket No. 50-281 I
Beam Direction Table 1 Surry Unit 2 Reactor Vessel Lower Circumferential Shell Weld 1-04 Coverage Percentages Examination Volume Coverage 45 degree L 45 degree L 45 degree Dual Single Shear ccw cw Weld Volume Weld Volume Weld Volume 73.3 78.1 87.9 83.0 87.9 83.0 73.3 78.1 87.9 83.0 87.9 83.0 UP DOWN 77.7 77.7 77.7 77.7 100 96.3 77.7 12.2 77.7 80.8 77.7 14.6 Note: The examination volume coverage calculations are broken down into coverage of the weld volume (Weld) and the 1 /2t base material volume (Volume) for each examination transducer and beam direction.
Note: The examination volume coverage is calculated by averaging the combined coverage obtained in each of the required examination beam directions with each of the qualified transducers.
Scans Parallel to the Weld Axis - CCW/CW Scans Perpendicular to the Weld Axis - UP/DN Examination Coverage = 76.3%