ML050960422
| ML050960422 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/05/2005 |
| From: | Stephen Monarque NRC/NRR/DLPM/LPD2 |
| To: | Christian D Virginia Electric & Power Co (VEPCO) |
| Monarques, S R, NRR/DLPM, 415-1544 | |
| References | |
| Download: ML050960422 (7) | |
Text
April 5, 2005 Mr. David A. Christian Sr. Vice President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Blvd.
Glen Allen, Virginia 23060-6711
SUBJECT:
SURRY POWER STATION, UNIT 1-REQUEST FOR ADDITIONAL INFORMATION REGARDING ASME SECTION XI INSERVICE INSPECTION PROGRAM PARTIAL EXAMINATION RELIEF REQUESTS
Dear Mr. Christian:
By letter dated October 11, 2004, Virginia Electric and Power Company (VEPCO) submitted proposed Relief Requests PRT-2 through PRT-6 for Surry Power Station, Unit 1. Based on its review of the October 11, 2004 submittal, the NRC staff has determined that additional information is required to complete its review.
The NRC staffs questions are provided in the Enclosure. We request a conference call with VEPCO to discuss these questions and to schedule a response to the RAI.
Sincerely,
/RA/
Stephen R. Monarque, Project Manager, Section 1 Project Directorate II Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-280
Enclosure:
As stated
ML050960422 NRR-088 OFFICE PDII-1/PM PDII-2/LA PDII-1/SC NAME SMonarque EDunnington JNakoski DATE 04/05/05 04/05/05 04/05/05
1.
Sketches provided by the licensee are not included in this report.
REQUEST FOR ADDITIONAL INFORMATION PARTIAL EXAMINATION RELIEF REQUESTS PRT-2 THROUGH PRT-5 SURRY POWER STATION, UNIT 1 VIRGINIA ELECTRIC AND POWER COMPANY 1.
SCOPE By letter dated October 11, 2004, Virginia Electric and Power Company (the licensee) submitted requests for relief from requirements of the American Society of Mechanical Engineers (ASME)
Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components. These requests were submitted as part of the inservice inspection (ISI) program for the third 10-year ISI interval at Surry Power Station, Unit 1.
Requests for Relief PRT-02, -03, -05, and -06 are requests on limited examination coverages for welds pursuant to 10 CFR 50.55a(g)(5)(iii). The regulation states that licensees, having determined that certain ASME requirements are impractical at their facility, must submit information to support this determination. The U.S. Nuclear Regulatory Commission (NRC) will evaluate these determinations and may grant relief and/or impose alternative requirements as deemed necessary. Request for Relief PRT-04 is a proposed alternative to the NRC-approved Risk-Informed ISI (RI-ISI) program, pursuant to 10 CFR 50.55a(a)(3)(i). The regulation at 10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if the licensee demonstrates that: (i) the proposed alternatives would provide an acceptable level of quality and safety or (ii) compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Pacific Northwest National Laboratory (PNNL) and the NRC staff have reviewed the licensees submittal and, based on this review, determined the following information is required to complete the evaluation for Relief Requests PRT-02, 03, 04, and 05. Additional information for Request for Relief PRT-06 is not required by the NRC staff for its review.
2.
REQUEST FOR ADDITIONAL INFORMATION 2.1 Request for Relief PRT-02, Examination Category C-C, Integral Attachments for Vessels, Piping, Pumps, and Valves 2.1.a The licensee stated, This component support has multiple integrally attached welds as shown in the sketches on pages 3 and 41. One portion consists of two clevis type attachments that were welded to the pipe prior to the installation of two clam shell type pieces that were assembled over the attachments. The two clam shell pieces were welded together with two longitudinal welds and then attached to the pressure boundary with two circumferential welds. One hundred percent (100%) coverage of the two circumferential welds was obtained.
2 Sketches provided by the licensee are not included in this report.
Please confirm whether the subject component support is fabricated of carbon or austenitic steel and what surface nondestructive examination (NDE) method was applied (liquid penetrant or magnetic particle testing).
2.1.b Please state the plant piping system for the subject request for relief.
2.2 Request for Relief PRT-03, Examination Category C-C, Integral Attachments for Vessels, Piping, Pumps, and Valves 2.2.a The licensee stated, This component support has multiple integrally attached welds as shown in the sketches on page 32. One portion consists of two clevis type attachments that were welded to the pipe prior to the installation of two clam shell type pieces that were assembled over the attachments. The two clam shell pieces were welded together with two longitudinal welds and then attached to the pressure boundary with two circumferential welds, thus rendering the clevis welds totally inaccessible. One hundred percent (100%) of the examination surface for the circumferential welds was obtained utilizing magnetic particle and liquid penetrant examination methods.
Please state the base material (carbon or austenitic steel). Describe which NDE surface technique was used for each portion of the component support and list any restrictions or limitations for that method.
2.2.b Please state the plant piping system for the subject request for relief.
2.3 Request for Relief PRT-04, Examination Category R-A, Full Penetration Piping Welds Governed by the Risk-Informed Program 2.3.a The licensee stated, Weld 1-05 is a circumferential weld joining a valve and a pipe tee.
The material type and outside profile do not allow for ultrasonic examination from the outside, resulting in no coverage of the examination volume in the 2 direction. Only 14%
of the examination volume could be attained in the 2 and 5 direction. For flaws oriented transverse to the welds, in the 7 and 8 scan direction, full coverage was attained. The total average percent coverage obtained was 57%. The following table was provided by the licensee.
Table 3.3 - % UT Scan Coverage at 45 degree Angle Beam Weld Scan Direction and Coverage Total Average 2
5 7
8 1-05 14%
14%
100%
100%
57%
1-11 0%
44%
100%
100%
61%
Please clarify the discrepancies stated in the paragraph above with the information shown on the table for scans 2 and 5 on both Welds 1-05 and 1-11. State whether scan 2 or scan 5 is performed from the cast valve side of Weld 1-05.
3.
The sketch provided by the licensee is not included in this report.
2.3.b The licensee stated for Weld 1-05, Ultrasonic shear wave examination was attempted on the tee and valve sides of the weld, and it was apparent that the material for these components is cast stainless steel. At elevated sensitivity levels, an inner diameter roll was not visible on the valve side, and excessive noise resulted on the tee side. The weld material was examined to the maximum extent practical in the 2, 5, 7, and 8 directions. Alternative ultrasonic techniques would not produce additional meaningful data.
The licensee also stated for Weld 1-11, Due to material type limitations of the tee (cast stainless) and the component outer diameter contour of the reducer, the examination volume was examined to the maximum extent practicable. Alternative ultrasonic techniques would not produce additional meaningful data.
Explain why other standard ultrasonic methods such as refracted longitudinal waves, lower frequencies, or phased array technology could not be used on the subject weld(s) to increase coverage. Many licensees have applied these techniques to austenitic welds to ensure coverage and penetration in coarse-grained materials, and procedures employing these techniques have successfully qualified under the industrys Performance Demonstration Initiative (PDI). Discuss these issues in regard to application on Welds 1-05 and 1-11, and clarify why these types of ultrasonic techniques would not substantially increase examination coverage for the subject welds.
2.3.c Finally, discuss why the partial examinations performed on Welds 1-05 and 1-11 provide an adequate basis to conclude that the targeted degradation mechanism (thermal fatigue) would have been detected, if present, in these welds. Include a description of the coverage(s) obtained during scans 2 and 5, and why these were adequate to detect any circumferentially oriented flaws that may be present.
2.4 Request for Relief PRT-05, Examination Category B-B, Pressure-Retaining Welds in Vessels Other Than Reactor Vessels 2.4.a The licensee provided, as Figure 13, a sketch showing how the pressurizer insulation support ring and the power-operated relief valve (PORV) welded support restrict access to make scans on Welds 1-07 and 1-15. This sketch adequately explains the limited access to examine the shell-to-head and intersecting longitudinal weld from the shell side. Also, the licensee provided the tables to indicate completed volumetric percentages for each of the scans on each weld. For example:
Table 1 Weld 1-07, % Volume by Scan Direction SCAN ANGLE, degrees SCAN DIRECTION SCAN AREA
% EXAMINED 0
0 Weld and Base Metal 68 45 2
Weld and Base Metal 82 60 2
Weld and Base Metal 20 45 5
Weld and Base Metal 15 60 5
Weld and Base Metal 20 45 7
Weld and Base Metal 35
Table 1 Weld 1-07, % Volume by Scan Direction SCAN ANGLE, degrees SCAN DIRECTION SCAN AREA
% EXAMINED 4.
Figures 2 and 3 are not included in this report.
60 7
Weld and Base Metal 35 45 8
Weld and Base Metal 35 60 8
Weld and Base Metal 35 Average Percent Examined for Weld 1-07: 38.3%
Based on the information in the table and figure, it is assumed that scan 2 was made from the head side of Weld 1-07, given that the 45-degree shear wave was able to achieve 82-percent coverage. However, it is unclear why the 60-degree shear wave scan 2, which places the transducer slightly farther from the weld, could only obtain 20-percent volumetric coverage. Please clarify this result with further information or provide a cross-sectional sketch to indicate coverages for all scans.
2.4.b In addition, no explanation to describe the information in Figures 2 or 34 is given in the licensees request. These appear to be cross-sectional drawings that depict volumetric coverage of Welds 1-07 and 1-15, respectively. The interferences shown in Figure 2 are labeled 2 x 2-inch welded pad, 1-inch instrumentation nozzle, and 6-inch safety valve support ring. Please explain whether these interferences impact the full length of Weld 1-07 or only near the PORV. Also, indicate which scans are directly affected by these interferences, and what portion of the entire length of the scan is impacted.
Finally, clarify whether the 45-degree circumferential scan 2 (82%) covered the full ASME Code-required examination volume except for a small length of weld, or covered 82 percent of the examination volume for the full length of the weld.
Surry Power Station, Units 1 & 2 cc:
Ms. Lillian M. Cuoco, Esq.
Senior Counsel Dominion Resources Services, Inc.
Building 475, 5th Floor Rope Ferry Road Waterford, Connecticut 06385 Mr. Donald E. Jernigan Site Vice President Surry Power Station Virginia Electric and Power Company 5570 Hog Island Road Surry, Virginia 23883-0315 Senior Resident Inspector Surry Power Station U. S. Nuclear Regulatory Commission 5850 Hog Island Road Surry, Virginia 23883 Chairman Board of Supervisors of Surry County Surry County Courthouse Surry, Virginia 23683 Dr. W. T. Lough Virginia State Corporation Commission Division of Energy Regulation Post Office Box 1197 Richmond, Virginia 23218 Dr. Robert B. Stroube, MD, MPH State Health Commissioner Office of the Commissioner Virginia Department of Health Post Office Box 2448 Richmond, Virginia 23218 Office of the Attorney General Commonwealth of Virginia 900 East Main Street Richmond, Virginia 23219 Mr. Chris L. Funderburk, Director Nuclear Licensing & Operations Support Dominion Resources Services, Inc.
Innsbrook Technical Center 5000 Dominion Blvd.
Glen Allen, Virginia 23060-6711