L-19-107, Impractical American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements
| ML19239A405 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley (NPF-073) |
| Issue date: | 08/27/2019 |
| From: | Penfield R FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-19-107 | |
| Download: ML19239A405 (31) | |
Text
Beaver Valley Power Station P.O. Box 4 FirstEnergy Nuclear Operating Company Shippingport, PA 15077 Rod L. Penfield 724-682-5234 Site Vice President Fax: 724-643-8069 L-19-107 10 CFR 50.55a ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
Beaver Valley Power Station, Unit No. 2 Docket No. 50-412, License No. NPF-73 Impractical American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements Pursuant to 10 CFR 50.55a(g)(5)(iii), FirstEnergy Nuclear Operating Company (FENOC) hereby provides the Nuclear Regulatory Commission (NRC) with the basis for the determination that the inservice examination of the welds listed below, as specified by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI, or as specified by the NRC approved Risk-Informed Inservice Inspection Program, have been determined to be impractical. These determinations are based on experience obtained during the Beaver Valley Power Station, Unit No. 2 third 10-year inservice inspection interval which began August 29, 2008 and ended August 28, 2018.
The affected welds are:
- 1. Surge nozzle weld 2RCS*PRE21-N-9
- 2. Safety relief nozzle weld 2RCS*PRE21-N-10
- 3. Safety relief nozzle weld 2RCS*PRE21-N-11
- 4. Safety relief nozzle weld 2RCS*PRE21-N-12
- 5. Power operated relief nozzle weld 2RCS*PRE21-N-13
- 6. Spray nozzle weld 2RCS*PRE21-N-14
- 8. Tubesheet to shell weld 2RSS-E21A-C-1
- 9. Tubesheet to shell weld 2RSS-E21A-C-11
- 10. Pipe to valve weld 2CHS-072-F02
- 11. Pipe to valve weld 2CHS-072-F03
- 12. Pipe to valve weld 2CHS-072-F06
- 13. Pipe to valve weld 2CHS-072-F07
- 14. Pipe to valve weld 2CHS-015-F02
- 15. Pipe to valve weld 2CHS-015-F03
- 16. Pipe to valve weld 2CHS-015-F06 August 27, 2019 FENOC
Beaver Valley Power Station, Unit No. 1 L-19-107 Page 2 17.Pipe to valve weld 2CHS-015-F07
- 18. Pipe to valve weld 2CHS-357-F13-C
- 19. Pipe to valve weld 2CHS-357-F12-C
- 20. Pipe to valve weld 2SIS-047-F-06
- 21. Pipe to valve weld 2SIS-047-F-07
- 22. Pipe to valve weld 2SIS-048-F-509
- 23. Pipe to valve weld 2SIS-048-F-05A
- 24. Pipe to valve weld 2SIS-091-F01
- 25. Pipe to valve weld 2SIS-091-F511 Information to support the basis for the impracticality determinations is provided in enclosures A, B, C, and D.
There are no regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Phil H. Lashley, Acting Manager - Nuclear Licensing and Regulatory Affairs, at 330-315-6808.
Sincerely,
~~
Enclosures:
A. Beaver Valley Power Station, Unit No. 2, 10 CFR 50.55a Request 2-TYP-3-B3.110-1, Revision 0 B. Beaver Valley Power Station, Unit No. 2, 10 CFR 50.55a Request 2-TYP-3-C2.21-1, Revision 0 C. Beaver Valley Power Station, Unit No. 2, 10 CFR 50.55a Request 2-TYP-3-C1.30-1, Revision 0 D. Beaver Valley Power Station, Unit No. 2, 10 CFR 50.55a Request 2-TYP-3-RA-1, Revision 0 cc: NRC Region I Administrator NRC Resident Inspector NRC Project Manager Director BRP/DEP Site BRP/DEP Representative
L-19-107 Enclosure A Beaver Valley Power Station, Unit No. 2 10 CFR 50.55a Request 2-TYP-3-B3.110-1, Revision 0 (5 pages follow)
10 CFR 50.55a Request Number: 2-TYP-3-B3.110-1, Revision 0 Page 1 of 5 Relief Request in accordance with 10 CFR 50.55a(g)(5)(iii)
--Inservice Inspection Impracticality--
- 1. ASME Code Components Affected There are a total of six Class 1, Category B-D, Item Number B3.110 nozzle to vessel welds affected on the pressurizer at Beaver Valley Power Station Unit No. 2 (BVPS-2).
2RCS*PRE21-N-9, weld 9, 14-inch nominal pipe size, Surge Nozzle 2RCS*PRE21-N-12, weld 12, 6-inch nominal pipe size, Safety Relief Nozzle 2RCS*PRE21-N-10, weld 10, 6-inch nominal pipe size, Safety Relief Nozzle 2RCS*PRE21-N-13, weld 13, 6-inch nominal pipe size, Power Operated Relief Nozzle 2RCS*PRE21-N-11, weld 11, 6-inch nominal pipe size, Safety Relief Nozzle 2RCS*PRE21-N-14, weld 14, 4-inch nominal pipe size, Spray Nozzle
2. Applicable Code Edition and Addenda
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda was applicable for the BVPS-2 third interval.
3. Applicable Code Requirement
Table IWB-2500-1, Examination Category B-D, Full Penetration Welded Nozzles in Vessels Inspection Program B, Item Number B3.110, requires volumetric exams in accordance with Figure IWB-2500-7(b), Nozzle in Shell or Head. Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI Division 1, Code Case N-460, as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent, that is greater than 90%
coverage is obtained.
4. Impracticality of Compliance
The examination volume requirement specified in Figure IWB-2500-7(b) for the noted welds has been determined to be impractical. These examinations are limited due to the nozzle curvature which causes the transducer to lose contact with the vessel surface.
Additionally, examination of the surge nozzle weld 9 is limited by heater penetrations which surround the nozzle.
10 CFR 50.55a Request Number: 2-TYP-3-B3.110-1, Revision 0 Page 2 of 5 Each of the pressurizer nozzle-to-vessel welds are essentially identical in configuration.
The carbon steel vessel head is joined to a forged nozzle with stainless steel cladding on the internal surfaces.
Table 1 provides the examination coverage for the upper head nozzle welds (10 through
- 14) for each scan angle used. Figure 1 diagrams the examination coverage on a cross section of the weld joints.
Table 2 identifies the examination coverage for the lower head surge nozzle weld 9.
Figure 2 provides the examination coverage on a cross section of the weld joint.
Table 1: Examination Coverage Details Applicable to Welds 2RCS*PRE21-N-10 through N-14 Exam Angle (degrees)
Beam Direction Code % Examined Limitation - clarification 0
N/A 80.0 Nozzle curvature 45 1
91.0 Nozzle curvature 45 2
33.0 Nozzle curvature 45 3
80.0 Nozzle curvature 45 4
80.0 Nozzle curvature 60 1
89.0 Nozzle curvature 60 2
16.4 Nozzle curvature 60 3
80.0 Nozzle curvature 60 4
80.0 Nozzle curvature Cumulative Coverage:
68.7 The 0 degree exam is not included in the code coverage calculations.
Table 2: Examination Coverage Details Applicable to Weld 2RCS*PRE21-N-9 Exam Angle (degrees)
Beam Direction Code % Examined Limitation - clarification 0
N/A 65.1 Nozzle curvature 45 1
95.0 Nozzle curvature and heater interference 45 2
45.4 Nozzle curvature 45 3
65.1 Nozzle curvature 45 4
65.1 Nozzle curvature 60 1
69.1 Nozzle curvature and heater interference 60 2
25.3 Nozzle curvature 60 3
65.1 Nozzle curvature 60 4
65.1 Nozzle curvature Cumulative Coverage:
61.9 The 0 degree exam is not included in the code coverage calculations.
10 CFR 50.55a Request Number: 2-TYP-3-83.110-1, Revision 0 Page 3 of 5 Shaded areas are areas where coverage could not be obtained for each scan Nozzle Overview of Coverage Area Area where contact is lost
~Coverage Area~
45 Degree Scan 1 t
- /
0 Degree, Scan 3 and 4 of 45 Degree, Scan 3 and 4 of 60 Degree 45 Degree Scan 2 60 Degree Scan 1 60 Degree Scan 2 r\\\\/
/
I Figure 1: Areas where coverage could not be obtained for weld 2RCS*PRE21-N-10 through N-14
10 CFR 50.55a Request Number: 2-TYP-3-B3.110-1, Revision 0 Page 4 of 5 Nozzle Shaded areas are areas where coverage could not be obtained for each scan Overview of Coverage Area Area where contact is Heater interferes Vessel Head 45 Degree Scan 1 C/L 60 Degree Scan 1 C/L O Degree, Scan 3 and 4 of 45 Degree, Scan 3 and 4 of 60 Degree C/L 45 Degree Scan 2 C/L 60 Degree Scan 2 Figure 2: Areas where coverage could not be obtained for weld 2RCS*PRE21-N-9
10 CFR 50.55a Request Number: 2-TYP-3-B3.110-1, Revision 0 Page 5 of 5
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign and replacement of the pressurizer tank nozzles and heater penetrations. Replacement of components to obtain the required inspection volume is contrary to the intent of the code.
Therefore, this option is considered impractical.
6. Proposed Alternative and Basis for Use
The proposed alternative to the examination volume requirement specified in Figure IWB-2500-7(b) is:
- To perform the ultrasonic examination to the maximum extent practicable.
- To continue performing periodic pressure testing in accordance with Category C-H of the ASME Section XI code.
The alternative to the examination volume requirement specified in Figure IWB-2500-7(b) is that the ultrasonic examination was performed to the maximum extent practicable. No recordable indications were found within the exam volume achieved.
The pressurizer is located in the reactor containment building. Although not accessible for walkdowns during normal operation, leakage rates within containment are monitored and sources identified as part of compliance to plant technical specifications. Per ASME Code Category C-H, a VT-2 exam for leakage is conducted at operating pressure after each outage during startup. Also, during outages the bolted connection on the manway located on the pressurizer upper head has insulation removed and a leakage exam performed per code requirements. Leakage resulting from degradation of the subject welds would be discovered within a reasonable amount of time.
A review of previous operating experience for both BVPS-2 and the industry did not reveal a history of problems in the nozzle to shell weld of the pressurizer.
The VT-2 examination, along with the UT examination coverage detailed above provide reasonable assurance of continued reliability of these welds. Condition monitoring already in place would detect a through wall leak within a reasonable amount of time.
7. Duration of Proposed Alternative
The proposed alternative is requested for the third 10-Year inservice inspection interval at BVPS-2, which began August 29, 2008 and ended August 28, 2018.
L-19-107 Enclosure B Beaver Valley Power Station, Unit No. 2 10 CFR 50.55a Request 2-TYP-3-C2.21-1, Revision 0 (4 pages follow)
10 CFR 50.55a Request Number: 2-TYP-3-C2.21-1, Revision 0 Page 1 of 4 Relief Request in accordance with 10 CFR 50.55a(g)(5)(iii)
--Inservice Inspection Impracticality--
- 1. ASME Code Component Affected The A Steam Generator Feedwater Inlet Nozzle to Vessel Weld 2RCS*SG21A-N-09 is a Class 2, Category C-B, Item Number C2.21 Nozzle to Vessel weld at Beaver Valley Power Station Unit No. 2 (BVPS-2).
2. Applicable Code Edition and Addenda
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda was applicable for the BVPS-2 third interval.
3. Applicable Code Requirement
Relief is requested from the volumetric examination requirement specified in Table IWC-2500-1, Examination Category C-B, Pressure Retaining Nozzle Welds in Vessels, item Number C2.21.
Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI Division 1, as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent, that is greater than 90% coverage is obtained.
4. Impracticality of Compliance
The examination volume requirement specified in Figure IWC-2500-4(a) for the affected weld has been determined to be impractical. When examined, the details of the weld joint design and obstruction by insulation support material prevented obtaining greater than 90% of the required examination volume.
2RCS*SG21A-N-09 is a shop weld joining the carbon steel feedwater nozzle to the carbon steel A steam generator secondary side vessel wall. There is no cladding.
This nozzle is a nominal pipe size of 16 inches. The nozzle transition is part of the nozzle with an attachment weld centerline diameter of 34 inches, and a material thickness of approximately 3.54 inches. This configuration is shown in ASME Section XI as Figure IWC-2500-4(a).
The limitation of examination volume was experienced during the volumetric exam using the ultrasonic technique. Scans are performed with 0, 45, and 60 degree transducers.
The 0-degree scan is a single scan and is not included in ASME code coverage calculations per First Energy Nuclear Operating Company (FENOC) procedure. For the
10 CFR 50.55a Request Number: 2-TYP-3-C2.21-1, Revision 0 Page 2 of 4 45 and 60 degree (shear wave) transducers, scans are performed in four directions. Two scans (scan 1 and 2) are perpendicular and two scans (scan 3 and 4) are near parallel to the weld bead direction. This results in a total of nine potential scans.
The exam coverage is limited by scan 2, which cannot be performed on the nozzle side of the weld due to the nozzle geometry. The transducer is lifted from the surface by the nozzle curvature before the exam area can be interrogated in the normal scan direction.
Some of the scan 2 was within the calibrated range of the instrument and was scanned via reflection form the component inner wall. This coverage is not credited in the calculations.
The exam coverage was also limited by a physical obstruction with a nearby insulation support. This support is a metal band installed around the steam generator body above the weld location. Figure 1 shows the nozzle and the angle iron support above it. This obstruction impeded coverage at the top of the weld for the 45 and 60 degree exams in direction 1. The examiner noted that partial coverage was obtained near the ends of the obstruction, but that this was not included in the coverage calculation. The coverage gained by removal of the insulation bracket would not have resulted in a complete exam.
See Table 1 for a summary of the coverage obtained.
Table 1: Volumetric Coverage Summary of 2RCS*SG21A-N-09 Exam Angle (degrees)
Beam Direction Code %
Examined Limitation - clarification 0
N/A 100 45 1 (from vessel side) 87 Insulation obstruction 45 2 (from nozzle side) 0 Nozzle configuration 45 3
100 45 4
100 60 1
85 Insulation obstruction 60 2
0 Nozzle configuration 60 3
100 60 4
100 Cumulative Coverage 71.5 The 0-degree scan is not included in coverage calculations.
10 CFR 50.55a Request Number: 2-TYP-3-C2.21-1, Revision 0 Page 3 of 4 Feedwater Piping Steam Generator vessel wall Figure 1: 2RCS*SG21A-N-09 nozzle and obstructing angle iron supports.
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign and replacement of the steam generator feedwater nozzle. Replacement of components to obtain the required volume is contrary to the intent of the code. Therefore, this option is considered impractical.
To remove the insulation bracket obstruction for the steam generator feedwater nozzle would require construction of extensive scaffolding followed by removal and storage of several complete rows of large insulation panels in a small space with limited storage capacity. Following this the installed bracketry would have to be removed for the exam with the potential for fit-up issues upon replacement. This work would be required within the steam generator cubicle where radiological dose rates are elevated.
For the same work in Beaver Valley Power Station, Unit No.1 (BVPS-1), the estimated man hours in the field for scaffold and insulation work was 936 hours0.0108 days <br />0.26 hours <br />0.00155 weeks <br />3.56148e-4 months <br /> with approximately 4.68 Roentgen Equivalent Man (REM) of radiological dose. This is in addition to the time and exposure of the examiners. Details of the insulation package in BVPS-2 are expected to add more time in the field over the estimates for BVPS-1. Discussion with insulators revealed a high likelihood that dose rates will also increase due to adjustments needed during reinstallation of the insulation support. It is likely that some insulation panels would have to be removed and reinstalled multiple times for fit-up.
Complete removal of the obstruction would result in a code coverage increase of approximately 3.5% to an overall 75% coverage.
10 CFR 50.55a Request Number: 2-TYP-3-C2.21-1, Revision 0 Page 4 of 4 Removal of the insulation was considered during preparations for the exam, but due to the man-hours and radiological dose needed to perform these actions the decision was made to obtain the best possible coverage with the bracketry in place. Therefore, this option is considered impractical.
6. Proposed Alternative and Basis for Use
The proposed alternative to the examination volume requirement specified in Figure IWC-2500-4(a) was to perform the ultrasonic examination to the maximum extent practicable, monitor for leakage, and continue leakage walkdowns. The percentage of the exam limitation has been detailed above. As noted above, the Ultrasonic Testing (UT) examination covered 71.5 percent of the required volume.
The entire coverage volume was scanned by the 0 degree, and in at least two directions for the 45-and 60-degree exam angles by scans 3 and 4, and much of it was covered in all four directions when additional uncredited coverage from reflection on the inside wall of the component is considered. No recordable indications were found.
ASME code also requires a surface exam of this weld. The surface exam was completed without coverage limitations and found no indications.
The steam generator is located in the reactor containment building. Although not accessible for walkdowns during normal operation, leakage rates within containment are monitored and sources identified as part of compliance to plant technical specifications.
Per ASME Code Category C-H, a VT-2 exam for leakage is conducted at operating pressure once per period (40 months), and any leakage would be noted during class 1 pressure test walkdowns performed after each outage during startup. Leakage resulting from degradation would be discovered within a reasonable amount of time.
A review of previous operating experience for both BVPS-2 and the industry did not reveal a history of problems in the feedwater nozzle to shell weld of the steam generators.
The VT-2 and surface examination, along with the UT examination coverage detailed above provide reasonable assurance of continued reliability of these welds. Condition monitoring already in place would detect a through-wall leak within a reasonable amount of time. Much of the limitation on coverage is due to the nozzle configuration and would require modification or replacement of the steam generator to improve. The limitation imposed by the obstruction is small and requires significant radiological dose to gain additional access. Due to these factors FENOC has determined the coverage requirement of IWC-2500-4(a) for this weld to be impractical.
7. Duration of Proposed Alternative
The proposed alternative is requested for the third 10-year inservice inspection interval at BVPS-2, which began August 29, 2008 and ended August 28, 2018.
L-19-107 Enclosure C Beaver Valley Power Station, Unit No. 2 10 CFR 50.55a Request 2-TYP-3-C1.30-1, Revision 0 (3 pages follow)
10 CFR 50.55a Request Number: 2-TYP-3-C1.30-1, Revision 0 Page 1 of 3 Relief Request in accordance with 10 CFR 50.55a(g)(5)(iii)
--Inservice Inspection Impracticality--
- 1. ASME Code Component(s) Affected The A Recirculation Spray Cooler Tubesheet to Shell welds 2RSS-E21A-C-1 and 2RSS-E21A-C-11 are Class 2, Category C-A, Item Number C1.30 welds at Beaver Valley Power Station Unit No. 2 (BVPS-2).
2. Applicable Code Edition and Addenda
The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, 2001 Edition through 2003 Addenda was applicable for the BVPS-2 third interval.
3. Applicable Code Requirement
Relief is requested from the volumetric examination requirement specified in Table IWC-2500-1, Examination Category C-A, Pressure Retaining Welds in Pressure Vessels, item number C1.30.
Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI Division 1, as an alternative approved for use by the NRC Staff, states that a reduction in examination coverage due to part geometry or interference for any Class 1 and 2 weld is acceptable provided that the reduction is less than 10 percent, greater than 90% coverage is obtained.
4. Impracticality of Compliance
The examination volume requirement specified in Figure IWC-2500-2 for the affected weld has been determined to be impractical. When examined, obstruction by seismic support lugs and nozzle reinforcing rings prevented obtaining greater than 90% of the required examination volume.
2RSS-E21A-C-1 and 2RSS-E21A-C-11 are shop welds joining the stainless steel tubesheets at the top and bottom of the heat exchanger to the stainless steel vessel wall. The two welds are essentially identical in configuration and exam coverage obstructions. The area of the weld is approximately 0.375 inch thick with a diameter of 34 inches. This configuration is shown in ASME Section XI as Figure IWC-2500-2.
The limitation of examination volume was experienced during the volumetric exam using the ultrasonic technique. Scans were performed with 0, 45, and 60 degree transducers.
The 0-degree scan is a single scan and is not included in ASME code coverage
10 CFR 50.55a Request Number: 2-TYP-3-C1.30-1, Revision 0 Page 2 of 3 calculations per First Energy Nuclear Operating Company (FENOC) procedure. For the 45 and 60 degree (shear wave) transducers, scans are performed in four directions. Two scans (scan 1 and 2) are perpendicular and two scans (scan 3 and 4) are near parallel to the weld bead direction. This results in a total of nine potential scans.
The exam coverage of each weld was limited by three physical obstructions. Two are due to seismic support lugs that are welded to the tube sheet just below and in close proximity to the weld of interest. The third obstruction is a nozzle reinforcing ring welded to the vessel wall just above one of the support lugs. Figure 1 shows the lower end of the vessel with the obstructions. The obstructions on the upper end of the vessel are identical in configuration. On one side, away from the nozzle, the lug prevents examination from the tubesheet side of the weld for approximately 10.5 inches of weld length. Examination was successfully performed from the vessel wall side and in both circumferential directions. On the other side, the lug and nozzle reinforcing ring prevent access for any of the required scans for approximately 10.5 inches of weld length. The resulting examination coverage for this weld is 85.25%.
Figure 1: 2RSS*E21A-C-1 and C-11 tubesheet-to-she/1 weld obstructions
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign and replacement of the seismic lugs, tubesheet, or nozzle on the recirculation spray cooler.
Replacement of components to obtain the required volume is contrary to the intent of the code. Therefore, this option is considered impractical.
10 CFR 50.55a Request Number: 2-TYP-3-C1.30-1, Revision 0 Page 3 of 3
6. Proposed Alternative and Basis for Use
The proposed alternative to the examination volume requirement specified in Figure IWC-2500-2 was to perform the ultrasonic examination to the maximum extent practicable, and to continue leakage walkdowns. The percentage of the exam limitation has been described above and was 85.25% of the required coverage volume.
For this exam, a support ring around the vessel was removed to provide the best access possible. Most of the weld length was unobstructed and fully scanned in all required directions. One scan direction was impeded above one lug and all scan directions were impeded between the other lug and the nozzle reinforcing ring. The resulting coverage was nearly enough to be found acceptable. No recordable indications were found.
The recirculation spray cooler is located in the safeguards building which is accessible during operation. Per ASME Code Category C-H, a VT-2 exam for leakage is conducted at operating pressure once per period (40 months). The tank is also surveilled during monthly walkdowns by system engineering. Leakage resulting from degradation would be discovered within a reasonable amount of time.
A review of operating experience for both BVPS-2 and the industry did not reveal a history of significant problems with this type of weld.
The VT-2 examination, along with the UT examination coverage provide reasonable assurance of continued reliability of these welds. Condition monitoring already in place would detect a through-wall leak within a reasonable amount of time. The coverage limitation would require significant modification or replacement of the cooler to improve.
Due to these factors FENOC has determined the coverage requirement of IWC-2500-2 for this weld to be impractical.
7. Duration of Proposed Alternative
The proposed alternative is requested for the third 10-Year inservice inspection interval at BVPS-2, which began August 29, 2008 and ended August 28, 2018.
L-19-107 Enclosure D Beaver Valley Power Station, Unit No. 2 10 CFR 50.55a Request 2-TYP-3-RA-1, Revision 0 (13 pages follow)
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 1 of 13 Relief Request in accordance with 10 CFR 50.55a(g)(5)(iii)
--Inservice Inspection Impracticality--
- 1. ASME Code Component(s) Affected There are a total of sixteen welds within eight Risk-Informed Inservice Inspection (RI-ISI)
Program pipe segments that were found to have limited examination coverage. These Beaver Valley Power Station, Unit No. 2 (BVPS-2) welds are American Society of Mechanical Engineers, Boiler and Pressure Vessel Code (ASME Code) Class 2, Risk-Informed Inservice Inspection (RI-ISI) Program, examination category R-A, item number R1.11 piping welds.
Table 1, Summary of Impractical Examinations, contains a listing of the affected welds and pipe segments.
2. Applicable Code Edition and Addenda
ASME Code,Section XI, 2001 Edition through 2003 Addenda.
3. Applicable Code Requirement
Weld examination volumetric coverage requirements of Figure IWC-2500-7, Welds in Piping, in accordance with the RI-ISI program.
4. Impracticality of Compliance
The examination requirements for ASME Code Class 2 piping welds at BVPS-2 for the third inservice inspection interval were governed by a RI-ISI program that was approved by the NRC staff in a safety evaluation dated March 23, 2011 (Accession No. ML110630403). The RI-ISI program was developed in accordance with WCAP-14572, Revision 1-NP-A, Westinghouse Owners Group Application of Risk-Informed Methods to Piping Inservice Inspection Topical Report. 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 examination of the required volume as described on Figure IWC-2500-7(a) for ASME Code Class 2 piping welds.
This program divided piping into segments and requires a complete volumetric examination on one weld within each high safety significant pipe segment. When an examination has limited examination coverage, the program requires examination of other weld(s) in the pipe segment if available. ASME Code Case N-460, Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1, as an alternative approved for use by the NRC staff, states in part that a reduction in examination coverage due to part geometry or interference for any Class 1 or Class 2 weld may be accepted provided the reduction in coverage is less than 10 percent [that is, greater than 90 percent coverage is obtained].
In accordance with 10CFR50.55a(g)(5)(iii), the examination volume requirement specified in Figure IWC-2500-7(a) for the noted welds has been determined to be impractical. Within these RI-ISI program pipe segments the examinable selections available were pipe to component welds, which contain geometry that prevents the component side axial scan. One weld was also obstructed by a code data plate. Per the RI-ISI program, when an examination yields a limited coverage volume another weld in the pipe segment is also examined if available. For each of the eight pipe segments in this relief request, another weld joint was examined; however, examination of the other weld joint also yielded limited examination coverage. See the table below for a summary of each weld examination and the cause of the
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 2 of 13 limited examination volume obtained. Additional details are discussed after the table. The symbol % is used for the word percent in the tables.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 3 of 13 Table 1: Summary of Impractical Examinations Component ID ASME Class Code Item Number Risk Informed Segment Configuration Material Pipe Size -
Schedule ASME Code figure Qualified Coverage Best Effort Coverage Impracticality 2CHS-072-F02 2
R1.11 CHS-026B Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel) 4-160 IWC-2500-7(a) 50 75 Single sided exam 2CHS-072-F03 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel) 4-160 IWC-2500-7(a) 44 44 Single sided exam and code plate obstruction 2CHS-072-F06 2
R1.11 CHS-026D Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel) 4-160 IWC-2500-7(a)
I 50 75 Single sided exam 2CHS-072-F07 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel) 4-160 IWC-2500-7(a) 50 75 Single sided exam
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 4 of 13 Table 1: Summary of Impractical Examinations Component ID ASME Class Code Item Number Risk Informed Segment Configuration Material Pipe Size -
Schedule ASME Code figure Qualified Coverage Best Effort Coverage Impracticality 2CHS-015-F02 2
R1.11 CHS-009 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 8-40S IWC-2500-7(a) 50 80 Single sided exam 2CHS-015-F03 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 8-40S IWC-2500-7(a) 50 80 Single sided exam 2CHS-015-F06 2
R1.11 CHS-008 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 8-40S IWC-2500-7(a) 50 80 Single sided exam 2CHS-015-F07 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 8-40S IWC-2500-7(a) 50 80 Single sided exam
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 5 of 13 Table 1: Summary of Impractical Examinations Component ID ASME Class Code Item Number Risk Informed Segment Configuration Material Pipe Size -
Schedule ASME Code figure Qualified Coverage Best Effort Coverage Impracticality 2CHS-357-F13-C 2
R1.11 CHS-018B Pipe to flange Flange-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel) 4-160 IWC-2500-7(a) 50 75 Single sided exam 2CHS-357-F12-C 2
R1.11 Reducing elbow to flange Flange-SA 182 F316 (forged stainless steel)
Elbow-SA 403 WP316 (Stainless Steel) 4-160 IWC-2500-7(a) 50 75 Single sided exam 2SIS-047-F-06 2
R1.11 SIS-032 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel)10-40S IWC-2500-7(a) 50 75 Single sided exam 2SIS-047-F-07 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel)10-40S IWC-2500-7(a) 50 75 Single sided exam
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 6 of 13 Table 1: Summary of Impractical Examinations Component ID ASME Class Code Item Number Risk Informed Segment Configuration Material Pipe Size -
Schedule ASME Code figure Qualified Coverage Best Effort Coverage Impracticality 2SIS-048-F-509 2
R1.11 SIS-033 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel)10-40S IWC-2500-7(a) 50 75 Single sided exam 2SIS-048-F-05A 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP316 (Stainless Steel)10-40S IWC-2500-7(a) 50 75 Single sided exam 2SIS-091-F01 2
R1.11 SIS-066 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 3-160 IWC-2500-7(a) 50 75 Single sided exam and elbow geometry 2SIS-091-F511 2
R1.11 Pipe to valve Valve-SA 182 F316 (forged stainless steel)
Pipe-SA 376 TP304 (Stainless Steel) 3-160 IWC-2500-7(a) 45 76 Single sided exam and elbow geometry
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 7 of 13 Risk Informed Pipe Segment CHS-026B CHS-026B is a short segment of 4-inch schedule 160 ASME Code Class 2 piping that connects two valves. This segment is located in the Chemical and Volume Control system after the high head safety injection charging pumps. The material of both the valve and piping is stainless steel. In this segment, one pipe to valve weld was selected and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. Due to the surface condition and geometry, a scan was possible on the valve side of the weld for the exam on weld F02. Because the examination angle is not maintained on the tapered valve surface, the exam is not credited in the qualified coverage calculation. A refracted longitudinal (RL) wave examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment CHS-026B is limited as noted in Table 2. The volumetric examination coverage attained found no recordable indications.
Table 2: Segment CHS-026B Examination Details Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2CHS-072-F02 45 and 60RL 50 75 Single sided exam, Valve body also scanned on the taper.
2CHS-072-F03 45, 60, and 60RL 44 44 Single sided exam, code plate obstruction.
Risk Informed Pipe Segment CHS-026D CHS-026D is a short segment of 4-inch schedule 160 ASME Code Class 2 piping that connects two valves. This segment is located in the Chemical and Volume Control system after the high head safety injection charging pumps. The material of both the valve and piping is stainless steel. In this segment, one pipe to valve weld was selected, and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. Due to the surface condition and geometry, a scan was possible on the valve side of the weld for the exam on weld F07. Because the examination angle is not maintained on the tapered valve surface, this is not credited in the qualified coverage calculation. A refracted longitudinal wave examination was also performed per procedure to improve examination coverage.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 8 of 13 The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment CHS-026D is limited as noted in Table 3. The volumetric examination coverage attained found no recordable indications.
Table 3: Segment CHS-026D Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2CHS-072-F06 45, 60, and 60RL 50 75 Single sided exam.
2CHS-072-F07 45 and 60RL 50 75 Single sided exam, Valve body also scanned on the taper.
Risk Informed Pipe Segment CHS-009 CHS-009 is a short segment of 8-inch schedule 40 ASME Code Class 2 piping that connects two valves. This segment is located in the Chemical and Volume Control system before the high head safety injection charging pumps. The material of both the valve and piping is stainless steel. In this segment, one pipe to valve weld was selected, and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. Due to the surface condition and geometry, a scan was possible on the valve side of both welds. Because the examination angle is not maintained on the tapered valve surface, this is not credited in the qualified coverage calculation. A 70-degree examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment CHS-009 is limited as noted in Table 4. The volumetric examination coverage attained found no recordable indications.
Table 4: Segment CHS-009 Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2CHS-015-F02 45 and 70 50 80 Single sided exam, Valve body also scanned on the taper.
2CHS-015-F03 45 and 70 50 80 Single sided exam, Valve body also scanned on the taper.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 9 of 13 Risk Informed Pipe Segment CHS-008 CHS-008 is a short segment of 8-inch schedule 40 ASME Code Class 2 piping that connects two valves. This segment is located in the Chemical and Volume Control system before the high head safety injection charging pumps. The material of both the valve and piping is stainless steel. In this segment, one pipe to valve weld was selected, and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. Due to the surface condition and geometry, a scan was possible on the valve side of both welds. Because the examination angle is not maintained on the tapered valve surface, this is not credited in the qualified coverage calculation. A 70-degree examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment CHS-008 is limited as noted in Table 5. The volumetric examination coverage attained found no recordable indications.
Table 5: Segment CHS-008 Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2CHS-015-F06 45 and 70 50 80 Single sided exam, Valve body also scanned on the taper.
2CHS-015-F07 45 and 70 50 80 Single sided exam, Valve body also scanned on the taper.
Risk Informed Pipe Segment CHS-018B CHS-018B is a short segment of 4-inch schedule 160 ASME Code Class 2 piping from the discharge flange of a high head safety injection system charging pump to a reducing elbow. The material of the flange, elbow and piping is stainless steel. In this segment, the pipe to flange weld was selected, and when the examination volume obtained was found to be limited, the pipe to elbow butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the flange or elbow geometry preventing one axial scan. A 60-degree refracted longitudinal examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 10 of 13 Ultrasonic examination coverage of welds within pipe segment CHS-018B is limited as noted in Table 6. The volumetric examination coverage attained found no recordable indications.
Table 6: Segment CHS-018B Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2CHS-357-F13-C 45 and 60RL 50 75 Single sided exam.
2CHS-357-F12-C 45 and 60RL 50 75 Single sided exam.
Risk Informed Pipe Segment SIS-032 SIS-032 is a short segment of 10-inch schedule 40S ASME Code Class 2 piping that connects two valves. This segment is located in the safety injection system after a recirculation spray pump. The material of both the valves and piping is stainless steel. In this segment, one pipe to valve weld was selected and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. A 70-degree examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment SIS-032 is limited as noted in Table 7. The volumetric examination coverage attained found no recordable indications.
Table 7: Segment SIS-032 Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2SIS-047-F-06 45 and 70 50 75 Single sided exam.
2SIS-047-F-07 45 and 70 50 75 Single sided exam.
Risk Informed Pipe Segment SIS-033 SIS-033 is a short segment of 10-inch schedule 40S ASME Code Class 2 piping that connects two valves. This segment is located in the safety injection system after a recirculation spray pump. The material of both the valves and piping is stainless steel. In this segment, one pipe to valve weld was selected and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. A 70-degree examination was also performed per procedure to improve examination coverage.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 11 of 13 The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment SIS-033 is limited as noted in Table 8. The volumetric examination coverage attained found no recordable indications.
Table 8: Segment SIS-033 Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2SIS-048-F-509 45 and 70 50 75 Single sided exam.
2SIS-048-F-05A 45 and 70 50 75 Single sided exam.
Risk Informed Pipe segment SIS-066 SIS-066 is a short segment of 3-inch schedule 160 ASME Code Class 2 piping that connects two valves. This segment is located in the safety injection system after the high head safety injection charging pumps. The material of both the valves and piping is stainless steel. In this segment, one pipe to valve weld was selected and when the examination volume obtained was found to be limited, the pipe to valve butt weld at the other end was also examined. Both welds were volumetrically examined using a BVPS procedure based on PDI-UT-2 and found to have limited qualified examination coverage due to the valve body geometry preventing one axial scan. Due to surface condition and geometry, a scan was possible on the valve side of the F01 weld. Because the exam angle is not maintained on the tapered valve surface, this is not credited in the qualified coverage calculation. A 70-degree examination was also performed per procedure to improve examination coverage.
The materials of construction reduce the possible qualified coverage due to ultrasound attenuation. Coverage that was obtained beyond that qualified by procedure is reported as Total % Examined in the table below.
Ultrasonic examination coverage of welds within pipe segment SIS-066 is limited as noted in Table 9. The volumetric examination coverage attained found no recordable indications.
Table 9: Segment SIS-066 Examination Details.
Weld Number Exam angles used Qualified %
Examined Total %
Examined Exam notes 2SIS-091-F01 45 and 70 50 75 Single sided exam.
2SIS-091-F511 45 and 70 45 76 Single sided exam. Loss of contact
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 12 of 13
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign and replacement of the piping segments and components discussed. Replacement of components to obtain the required volume is contrary to the intent of the code. Therefore, this option is considered impractical.
6. Proposed Alternative and Basis for Use
The proposed alternative would permit the qualified ultrasonic weld examination coverage percent obtained for the welds specified in Table 1, Summary of Impractical Examinations, above, instead of the complete weld examination volume requirements of Figure IWC-2500-7, Welds in Piping as specified in the BVPS Risk-Informed Inservice Inspection (RI-ISI) program.
The BVPS-2 RI-ISI program requires complete volumetric examination coverage of one weld within each high safety significant pipe segment listed in Table 1. The postulated damage mechanism for these pipe segments was thermal fatigue. For each of these pipe segments the welds that could be selected would result in a single sided axial examination and its associated coverage limitations. After examination resulted in limited coverage area for the selected welds, the additional welds available were also examined and resulted in limited coverage. As a result, 16 limited coverage examinations were performed in an attempt to fully examine one weld in each of the 8 pipe segments. The 16 examinations found no recordable indications.
The pipe segments discussed are constructed of stainless steel. The materials and methods of construction employed are generally considered reliable within the nuclear industry. The pipe segments discussed are located in the Primary Auxiliary Building or in the Safeguards building and accessible during normal operation. Per ASME Code Category C-H, Class 2 pipe segments receive a VT-2 examination for leakage at operating pressure once per period (40 months). These areas are also surveilled on a monthly basis during walkdowns by system engineering personnel. Therefore, leakage resulting from degradation would be discovered within a reasonable amount of time.
The proposed alternative would accept the performance of the ultrasonic examinations to the maximum extent practicable on multiple welds located in the pipe segments listed in Table 1 in lieu of a complete exam of the required volume of one of the welds. This proposed alternative, along with monitoring for leakage via the VT-2 examinations and engineering walkdowns, will provide acceptable means to ensure the continued reliability of these piping segments and prompt identification of problems.
Therefore, in accordance with 10 CFR 50.55a(g)(5)(iii) FENOC has determined that the required examination coverage for these welds is impractical and requests that the proposed alternative examinations be considered an acceptable alternative to the examination coverage requirement.
10 CFR 50.55a Request Number: 2-TYP-3-RA-1, Revision 0 Page 13 of 13
7. Duration of Proposed Alternative
The proposed alternative is requested for the third 10-year inservice inspection interval at BVPS-2 which began August 29, 2008 and ended August 28, 2018. For the purpose of performing a replacement exam on 2SIS-091-F01, the end of the interval was extended to August 15, 2019.