L-08-069, Impractical American Society of Mechanical Engineers Code Section XI Weld Examination Requirements (Request Nos. 1-TYP-3-RA-1, 1-TYP-3-RA-2, 1-TYP-3-RA-3)
| ML081020295 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/09/2008 |
| From: | Sena P FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-08-069 | |
| Download: ML081020295 (11) | |
Text
.FENOC FirstEnergyNuclear OperatingCompany PeterP. Sena III 724-682-5234 Site Vice President. Fax: 724-643-8069 April 9, 2008 L-08-069 10 CFR 50.55a(g)(5)(iii)
ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Impractical American Society of Mechanical Engineers Code Section Xl Weld Examination Requirements (Request Nos. 1-TYP-3-RA-1, 1-TYP-3-RA-2, 1-TYP-3-RA-3)
Pursuant to 10 CFR 50.55a(g)(5)(iii), if the licensee has determined that conformance with certain code requirements is impractical for its facility, the licensee shall notify the Nuclear Regulatory Commission (NRC) and submit information to support the determinations. Pursuant to 10 CFR 50.55a(g)(5)(iv), the basis for this determination must be demonstrated to the satisfaction of the NRC not later than 12 months after the expiration of the ten-year inservice inspection interval. The Beaver Valley Power Station (BVPS) Unit No. 1 third ten-year inservice inspection interval ended on March 31, 2008.
Pursuant to 10 CFR 50.55a(g)(5)(iii), FirstEnergy Nuclear Operating Company (FENOC) hereby notifies the NRC that inservice examination of the required volume for certain Reactor Coolant System and Safety Injection System piping welds, as specified by the NRC approved Risk-Informed Inservice Inspection Program, has been determined to be impractical. This determination is based on experience obtained during the BVPS Unit No. 1 third ten-year inservice inspection interval.
Beaver Valley Power Station, Unit No. 1 L-08-069 Page 2 Consistent with 10 CFR 50.55a(g)(4) requirements, as modified by American Society of Mechanical Engineers Boiler and Pressure Vessel Code Case N-460, FENOC performed the weld examinations during the third ten-year interval to the extent practical within the limitations of design, geometry and materials of construction, but with coverage less than 100 percent. Therefore, it is requested that the NRC grant relief in accordance with 10 CFR 50.55a(g)(6) for the fourth ten-year interval. The details of the determinations of impracticality and the associated relief requests are provided in the attachments to this letter.
There are no regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Thomas A. Lentz, Manager -
FENOC Fleet Licensing, at 330-761-6071.
Sincerely, Peter P. Sena Ill Attachments:
- 1. 10 CFR 50.55a Request Number 1-TYP-3-RA-1, Revision 0
- 2. 10 CFR 50.55a Request Number 1-TYP-3-RA-3, Revision 0
- 3. 10 CFR 50.55a Request Number 1-TYP-3-RA-2, Revision 0 cc: Mr. S. J. Collins, NRC Region I Administrator Mr. D. L. Werkheiser, NRC Senior Resident Inspector Ms. N. S. Morgan, NRR Project Manager Mr. D. J. Allard, Director BRP/DEP Mr. L. E. Ryan (BRP/DEP)
ATTACHMENT 1 L-08-069 10 CFR 50.55a Request Number 1-TYP-3-RA-1, Revision 0 Page 1 of 3 Determination of Inservice Inspection Impracticality In Accordance with 10 CFR 50.55a(g)(5)(iii)
1.0 ASME Code Components Affected
Class 1 Reactor Coolant System circumferential butt welds DLW-LOOP2-6-F-21 (F-21) and DLW-LOOP2-6-F-22 (F-22) at Beaver Valley Power Station (BVPS) Unit No. 1 2.0 Applicable Code Edition and Addenda American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, 1989 Edition, no Addenda (third ten-year inservice inspection interval)
ASME Code Section XI, 2001 Edition, 2003 Addenda (fourth ten-year inservice inspection interval) 3.0 Applicable Code Requirements The examination coverage requirements for welds F-21 and F-22 that are applicable during the fourth ten-year inservice inspection interval are the same as those applicable during the third ten-year inservice inspection interval. During the third ten-year inservice inspection interval, examination requirements for Class 1 and 2 piping welds at BVPS Unit No. 1 are governed by a Risk-Informed Inservice Inspection (RI-ISI) program authorized by the NRC in a letter and safety evaluation dated April 9, 2004 (Accession Number ML040780805).
The RI-ISI program was developed in accordance With WCAP-14572, Rev. 1-NP-A, Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report (WCAP). Table 4.1-1 of WCAP-14572 assigns the Examination Category R-A, Item R1.11 to piping elements subject to thermal fatigue and requires 100 percent examination of the required volume as described on Figure IWB-2500-8(c) for Class 1 circumferential piping welds. ASME Code Section XI, Figure IWB-2500-8(c) is also applicable during the fourth tenmyear inservice inspection interval.
ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference by another component for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent (that is, greater than 90 percent coverage is obtained).
L-08-069 Page 2 of 3 4.0 Impracticality of Compliance The affected welds are located on piping segment RC-01 1. This segment consists of the 27.5 inch inside diameter A351 Grade CF8M piping segment between the discharge of the "B" reactor coolant pump and the cold leg loop isolation valve. Only two circumferential welds (F-21 and F-22) exist in piping segment RC-01 1.
During the third ten-year inservice inspection interval the RI-ISI program categorized piping segment RC-011 as High Safety Significant, and selected weld F-22 on this segment for examination as a "l (b)" or sample selection. The postulated damage mechanism for piping segment RC-01 1 is thermal fatigue. The BVPS Unit No. 1 RI-ISI program requires 100 percent volumetric examination coverage on weld F-22.
The WCAP recommends selection of an additional weld if a limited examination is obtained. Due to examination limitations encountered with weld F-22 during the third ten-year inservice inspection interval, weld F-21 was added to the examination scope and scheduled for examination. Limitations were also reported on weld F-21.
The following paragraphs describe examination coverage limitations encountered during the third ten-year inservice inspection interval for both welds. Examination coverage results are presented in the table on page 3.
The axial examination direction was possible on only one side of the welds. No coverage in the upstream (US) axial scan direction was possible for weld F-21, and no coverage in the downstream (DS) axial scan direction was possible for weld F-22.
Weld F-21 is a circumferential butt weld joining the reactor coolant pump outlet to the 27.5 inch inside diameter A351 Grade CF8M piping segment. The tapered profile of the weld as well as the physical configuration of the reactor coolant pump outlet combine to prohibit axial ultrasonic scan coverage from the upstream side (pump side) of the weld.
One hundred (100) percent coverage of the required examination volume was obtained in both circumferential scan directions. Additionally, 95.5 percent axial ultrasonic scan coverage was obtained from the downstream side of the weld. Simple averaging of the coverage attained results in a cumulative calculated coverage of 73.8 percent of the required examination volume.
Weld F-22 is a circumferential butt weld joining the 27.5 inch inside diameter A351 Grade CF8M piping segment to the cold leg loop isolation valve. The tapered profile of the weld as well as the physical configuration of the cast loop isolation valve combine to prohibit axial ultrasonic scan coverage from the downstream side (valve side) of the weld. One hundred (100) percent coverage of the required examination volume was obtained in both circumferential scan directions. Additionally, 99.6 percent axial ultrasonic scan coverage was obtained from the upstream side of the weld. Simple
Attachment 1 L-08-069 Page 3 of 3 averaging of the coverage attained results in a cumulative calculated coverage of 74.9 percent of the required examination volume.
Percent UT Scan Coverage with 45 Degree Refracted Longitudinal Angle Beam Scan Direction and Coverage Total Average Weld Coverage
.. ..... US IDS CW CCW DLW-LOOP2-6-F-21 0 95.5 100 100 73.8 DLW-LOOP2-6-F-22 99.6 0 100 100 74.9 UT - Ultrasonic, US - Upstream, DS - Downstream, CW - Clockwise, CCW - Counterclockwise 5.0 Burden Caused by Compliance In order to meet the volumetric coverage requirements, these welds (F-21 and F-22) would have to be re-designed and modified. Re-design and modification of components to obtain the required examination volume is contrary to the intent of the code.
Therefore, this option is considered impractical.
6.0 Proposed Alternative and Basis for Use As an alternative to the 100 percent examination volume requirement for weld DLW-LOOP2-6-F-22, ultrasonic examination to the maximum extent practicable on both circumferential welds DLW-LOOP2-6-F-21 (F-21) and DLW-LOOP2-6-F-22 (F-22),
located in piping segment RC-011, is proposed.
The proposed alternative examinations add one weld to the examination scope that would not otherwise be examined. In addition, these welds (F-21 and F-22) receive VT-2 examinations in accordance with Category B-P, which would detect through-wall
.leakage. Performance of proposed alternative ultrasonic examinations to the maximum extent possible, along with the VT-2 examinations, provides assurance of continued reliability for piping segment RC-01 1.
7.0 Duration of the Relief Request and Proposed Alternative The proposed alternative is requested for the fourth ten-year inservice inspection interval at BVPS Unit No. 1.
ATTACHMENT 2 L-08-069 10 CFR 50.55a Request Number 1-TYP-3-RA-3, Revision 0 Page 1 of 3 Determination of Inservice Inspection Impracticality In Accordance with 10 CFR 50.55a(g)(5)(iii)
1.0 ASME Code Components Affected
Class 1 Reactor Coolant System circumferential butt welds DLW-LOOP3-6-F-33 (F-33) and DLW-LOOP3-6-F-34 (F-34) at Beaver Valley Power Station (BVPS) Unit No. 1 2.0 Applicable Code Edition and Addenda American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, 1989 Edition, no Addenda (third ten-year inservice inspection interval)
ASME Code Section XI, 2001 Edition, 2003 Addenda (fourth ten-year inservice inspection interval) 3.0 Applicable Code Requirement The examination coverage requirements for welds F-33 and F-34 that are applicable during the fourth ten-year inservice inspection interval are the same as those applicable during the third ten-year inservice inspection interval. During the third ten-year inservice inspection interval, examination requirements for Class 1 and 2 piping welds at BVPS Unit No. 1 are governed by a Risk-Informed Inservice Inspection (RI-ISI) program authorized by the NRC in a letter and safety evaluation dated April 9, 2004 (Accession Number ML040780805).
The RI-ISI program was developed in accordance with WCAP-14572, Rev. 1-NP-A, Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report (WCAP). Table 4.1-1, of WCAP-14572 assigns the Examination Category R-A, Item R1.11 to piping elements subject to thermal fatigue and requires 100 percent examination of the required volume as described on Figure IWB-2500-8(c) for Class 1 circumferential piping welds. ASME Code Section XI, Figure IWB-2500-8(c) is also applicable during the fourth ten-year inservice inspection interval.
ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference by another component for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent (that is, greater than 90 percent coverage is obtained).
L-08-069 Page 2 of 3 4.0 Impracticality of Compliance The affected welds are located on piping segment RC-012. This segment consists of the 27.5 inch inside diameter A351 Grade CF8M piping segment between the discharge of the "C" reactor coolant pump and the cold leg loop isolation valve. Only two circumferential welds (F-33 and F-34) exist in piping segment RC-012.
During the third ten-year inservice inspection interval the RI-ISI program categorized piping segment RC-012 as High Safety Significant, and selected weld F-34 On this segment for examination as a "1(b)" or sample selection. The postulated damage mechanism for piping segment RC-012 is thermal fatigue. The BVPS Unit No. 1 RI-ISI program requires 100 percent volumetric examination coverage on weld F-34.
The WCAP recommends selection of an additional weld if a limited examination is obtained. Due to examination limitations encountered with weld F-34 during the third ten-year inservice inspection interval, weld F-33 was added to the examination scope and scheduled for examination. Limitations were also reported on weld F-33.
The following paragraphs describe examination coverage limitations encountered during the third ten-year inservice inspection interval for both welds. Examination coverage results are presented in the table on page 3.
The axial examination direction was possible on only one side of the welds. No coverage in the upstream (US) axial scan direction was possible for weld F-33, and no coverage in the downstream (DS) axial scan direction was possible for weld F-34.
Weld F-33 is a circumferential butt weld joining the reactor coolant pump outlet (A351 CF8 casing) to the 27.5 inch inside diameter A351 Grade CF8M piping segment. The tapered profile of the weld as well as the physical Configuration of the reactor coolant pump outlet combine to prohibit axial ultrasonic scan coverage from the upstream side (pump side) of the weld. Ninety (90) percent coverage of the required examination volume was obtained in both circumferential scan directions. Additionally, 80.3 percent axial ultrasonic scan coverage was obtained from the downstream side of the weld.
Simple averaging of the coverage attained results in a cumulative calculated coverage of 65.1 percent of the required examination volume.
Weld F-34 is a circumferential butt weld joining the 27.5 inch inside diameter A351 Grade CF8M piping segment to the cold leg loop isolation valve (SA-351-CF8M body).
The tapered profile of the weld as well as the physical configuration of the cast loop isolation valve combine to prohibit axial ultrasonic scan coverage from the downstream side (valve side) of the weld. One hundred (100) percent coverage of the required examination volume was obtained in both circumferential scan directions. Additionally, 100 percent axial ultrasonic scan coverage was obtained from the upstream side of the L-08-069 Page 3 of 3 weld. Simple averaging of the coverage attained results in a cumulative calculated coverage of 75 percent Of the required examination volume.
Percent UT Scan Coverage with 45 Degree Refracted Longitudinal Angle Beam Scan Direction and Coverage Total Average Weld Coverage US DS CW CCW DLW-LOOP3-6-F-33 0 80.3 90 90 65.1 DLW-LOOP3-6-F-34 100 0 100 100 75 UT - Ultrasonic, US - Upstream, DS - Downstream, CW - Clockwise, CCW - Counterclockwise 5.0 Burden Caused by Compliance In order to meet the volumetric coverage requirements, these welds (F-33 and F-34) would have to be re-designed and modified. Re-design and modification of components to obtain the required examination volume is contrary to the intent of the code.
Therefore, this option is considered impractical.
6.0 Proposed Alternative and Basis for Use As an alternative to the 100 percent examination volume requirement for weld DLW-LOOP3-6-F-34, ultrasonic examination to the maximum extent practicable on both circumferential welds DLW-LOOP3-6-F-33 (F-33) and DLW-LOOP3-6-F-34 (F-34),
located in piping segment RC-012, is proposed.
The proposed alternative examination adds one weld to the examination scope that would not otherwise be examined. In addition, these welds (F-33 and F-34) receive VT-2 examinations in accordance with Category B-P, which would detect through-wall leakage. Performance of the proposed alternative ultrasonic examination to the maximum extent practicable, along with the VT-2'examinations, provides acceptable means to ensure the continued reliability of piping segment RC-012.
7.0 Duration of the Relief Request and Proposed Alternative The proposed alternative is requested for the fourth ten-year inservice inspection interval at BVPS Unit No. 1.
ATTACHMENT 3 L-08-069 10 CFR 50.55a Request Number 1-TYP-3-RA-2, Revision 0 Page 1 of 3 Determination of InService Inspection Impracticality In Accordance with 10 CFR 50.55a(g)(5)(iii)
1.0 ASME Code Components Affected
Class 2 Safety Injection System circumferential butt weld S1-16-9-F-09 at Beaver Valley Power Station (BVPS) Unit No. 1 2.0 Applicable Code Edition and Addenda American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)Section XI, 1989 Edition, no Addenda (third ten-year inservice inspection interval)
ASME Code Section XI, 2001 Edition, 2003 Addenda (fourth ten-year inservice inspection interval) 3.0 Applicable Code Requirements The examination coverage requirements for weld SI-169-F-09 that are applicable during the fourth ten-year inservice inspection interval are the same as those applicable during the third ten-year inservice inspection interval. During the third ten-year inservice inspection interval, examination requirements for Class 1 and 2 piping welds at BVPS Unit No. 1 are governed by a Risk-Informed Inservice Inspection (RI-ISI) program authorized by the NRC in a letter and safety evaluation dated April 9, 2004 (Accession Number ML040780805).
The RI-ISI program was developed in accordance with WCAP-14572, Rev. 1-NP-A, Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report (WCAP). Table 4.1-1 of WCAP-14572 assigns the Examination Category R-A, Item R1.11 to piping elements subject to thermal fatigue and requires 100 percent examination of the required volume as described on Figure IWC-2500-7(a) for Class 2 full penetration welds in piping. ASME Code Section XI, Figure IWC-2500-7(a) is also applicable during the fourth ten-year inservice inspection interval.
ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference by another component for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent (that is, greater than 90 percent coverage is obtained).
L-08-069 Page 2 of 3 4.0 Impracticality of Compliance Weld SI-16-9-F-09 is located within RI-ISI piping segment SI-042A. This segment consists of a 10-inch diameter piping segment between valves MOV-SI-864A and -
864B, and is located in the low head safety injection flow path to the reactor coolant cold legs. The RI-ISI program categorized this piping segment as High Safety Significant. Thermal fatigue is the postulated damage mechanism for this piping segment.
Piping segment SI-042A is comprised of a single nominal pipe size with three different schedules. The RI-ISI program selected one weld as "l(a)" or mandatory in the Schedule 10S section and one weld in either the Schedule 40S or Schedule 160 section as "1(b)" or sample selection. One weld in the Schedule 10S section and one weld in the Schedule 40S section were selected.
Both the "l(a)" and "l(b)" weld examinations were completed without limitation or indication. However, as a result of an NRC request for information regarding segments containing multiple pipe sizes, FENOC identified a concern with the different residual stress levels dictated by pipe schedule and committed to perform a third weld examination under the RI-ISI program in piping segment SI-042A (Accession Number ML033070119). A weld (S1-16-9-F-09) was selected for examination in the Schedule 160 portion of segment SI-042A to address the concern.
Weld S1-16-9-F-09 was examined as described below during the third ten-year inservice inspection interval and the examination resulted in the limited volume coverage noted in the table on page 3.
The BVPS Unit No. 1 RI-ISI program requires 100 percent volumetric examination coverage (as described in Section 3.0 above) for weld SI-16-9-F-09 during the third ten-year inservice inspection interval. This 100 percent examination volume requirement was determined to be impractical due to the configuration of the weld. The axial examination direction is possible on only one side of the weld.
Weld Si-16-9-F-09 is a circumferential butt weld joining a 10 inch diameter stainless steel piping segment to a cast valve body. The physical configuration of the cast valve body prohibits axial ultrasonic scan coverage from the downstream (DS) side (valve side) of the weld. One hundred (100) percent coverage of the required examination volume was obtained in both circumferential scan directions. Additionally, 100 percent axial ultrasonic scan coverage was obtained from the upstream (US) side of the weld.
Simple averaging of the coverage attained results in a cumulative calculated coverage of 75 percent of the required examination volume. No coverage in the downstream axial scan direction was possible.
L-08-069 Page 3 of 3 Percent UT Scan Coverage with 45 Degree Shear Wave And Refracted Longitudinal Wave Beams Scan Direction and Coverage Total Average Weld Coverage US DS CW CCW SI-16-9-F-09 100 0 100 100 75 UT - Ultrasonic, US - Upstream, DS - Downstream, CW - Clockwise, CCW - Counterclockwise WCAP-14572 recommends selection of an additional weld if a limited examination is obtained. There is no other Schedule 160 full penetration weld in piping segment SI-042A.
There is one fillet weld in the Schedule 160 Section, located on the adjacent slip-on flange. A surface examination (liquid penetrant) was completed on the fillet weld, without limitation or indication.
5.0 Burden Caused by Compliance In order to meet the volumetric coverage requirements, weld S1-16-9-F-09 would have to be re-designed and modified. Re-design and modification of components to obtain the required examination volume is contrary to the intent of the code. Therefore, this option is considered impractical.
6.0 Proposed Alternative and Basis for Use As an alternative to the 100 percent examination volume requirement for weld SI-16 F-09, ultrasonic examination of weld SI-16-9-F-09 to the maximum extent practicable, and performance of a surface examination of the remaining fillet weld in the Schedule 160 section of piping segment SI-042A, is proposed.
Piping segment SI-042A receives VT-2 examinations in accordance with Category C-H, which would detect through-wall leakage. Performance of the proposed alternative ultrasonic examination to the maximum extent possible and the surface examination of the fillet weld, along with the VT-2 examinations, provides assurance of continued reliability of piping segment S-042A.
7.0 Duration of the Relief Request and Proposed Alternative The proposed alternative is requested for the fourth ten-year inservice inspection interval at BVPS Unit No. 1.