L-19-106, Unit 1, Impractical American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements
| ML19238A056 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/23/2019 |
| From: | Penfield R FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-19-106 | |
| Download: ML19238A056 (21) | |
Text
August 23, 2019 FENOC FirstEnergy Nuclear Operating Company Rod L. Penfield Site Vice President L-19-106 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 Beaver Valley Power Station P.O. Box 4 Shippingport, PA 15077 724-682-5234 Fax: 724-643-8069 10 CFR 50.55a 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 lnservice Inspection Program, have been determined to be impractical. These determinations are based on experience obtained during the Beaver Valley Power Station, Unit No. 1 fourth 10-year inservice inspection interval which began April 1, 2008 and ended August 28, 2018.
The affected welds are:
- 1. Safety injection boric acid tank nozzle-to-vessel weld SI-TK-2-N-3
- 2. Safety injection boric acid tank nozzle-to-vessel weld SI-TK-2-N-4
- 3. Steam generator nozzle-to-vessel weld RC-E-1A-N-9
- 4. Residual heat removal pipe segment to isolation valve weld RH-1-3-F-04
- 5. Residual heat removal pipe segment to isolation valve weld RH-1-3-F-05
- 6. Residual heat removal pump outlet to pipe reducer weld RH-4-1-F-01
- 7. Residual heat removal discharge valve to pipe reducer weld RH-4-1-F-02
- 8. Residual heat removal pump outlet to pipe weld RH-5-1-F-01
- 9. Residual heat removal discharge valve to pipe reducer weld RH-5-1-F-02
- 10. Refueling water storage tank flange to nozzle weld QS-9-1-F-01 Information to support the basis for the impracticality determinations is provided in enclosures A and B.
Beaver Valley Power Station, Unit No. 1 L-19-106 Page 2 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,
{jt~ jJ Rod L. Penfield
Enclosures:
A. Beaver Valley Power Station, Unit No.1, 10 CFR 50.55a Request 1-TYP-4-C2.21-1, Revision 0 B. Beaver Valley Power Station, Unit No.1, 10 CFR 50.55a Request 1-TYP-4-RA-1, Revision 0 cc: NRC Region I Administrator NRC Resident Inspector NRC Project Manager Director BRP/DEP Site BRP/DEP Representative
L-19-106 Enclosure A Beaver Valley Power Station, Unit No. 1 10 CFR 50.55a Request 1-TYP-4-C2.21-1, Revision 0
( 11 pages follow)
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 1 of 11 Relief Request in Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice Inspection Impracticality--
- 1. ASME Code Component{s) Affected There are a total of three Class 2, Category C-B, Item Number C2.21 nozzle to vessel welds affected on two vessels at Beaver Valley Power Station Unit No. 1 (BVPS-1 ).
Safety Injection Boric Acid Tank Nozzle Weld SI-TK-2-N-3 Safety Injection Boric Acid Tank Nozzle Weld SI-TK-2-N-4 "A" Steam Generator Feedwater Inlet Nozzle to Vessel Weld RC-E-1A-N-09
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 Unit 1 fourth interval.
3. Applicable Code Requirement
Table IWC-2500-1, "Examination Category C-B, Pressure Retaining Nozzle Welds in Vessels,"
Item Number C2.21 requires examination of welds in accordance with Figure No.
IWC-2500-4(a), (b), or (d) "Nozzle-To-Vessel Welds."
Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds," states, in part, 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 in coverage is less than 10 percent
(%) (greater than 90% coverage is obtained).
4. Impracticality of Compliance
The examination volume requirement specified in Figure IWC-2500-4 for the affected components in Section 1 of this request has been determined to be impractical. For the steam generator feedwater inlet nozzle weld (RC-E-1A-N-09), the surface exam area has also been determined to be impractical.
When examined, the details of the weld joint design and obstructions by insulation support material prevented obtaining greater than 90% of the required examination volume (or area for the surface exam). Table 1 provides a summary of details for each weld and the cause of the limited exam volume or area. Additional component examination details are discussed after the table.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 2 of 11 Table 1: S fl.
tical E Component/
Pipe Size-Description /
Exam ASME Class/
Material Thickness Configuration (inches)
SI-TK-2-N-3 /
Safety injection boric acid tank/
Class 2 /
Vessel head-A516 GR 70 with A240 TP 304 cladding 6 - 2.125 Nozzle to vessel (carbon steel plate, rolled and with stainless cladding) weld Nozzle-SA 350 LF2 (carbon steel forging)
SI-TK-2-N-4 /
Safety injection boric acid tank/
Class 2 /
Vessel head-A516 GR 70 with A240 TP 304 cladding 6 - 2.27 Nozzle to vessel (carbon steel plate, rolled and with stainless cladding) weld Nozzle-SA 350 LF2 (carbon steel forging)
RC-E-lA-N-9 /
Steam Generator/
Class 2 /
Vessel wall-SA 508 Cl 3 (carbon steel forging) 16 - 4.21 Nozzle to vessel Nozzle-SA 508 Cl 3a (carbon steel forging) weld ASME Item ASME Code Impracticality-Cause for limited Number and Coverage examination volume or area.
Figure Obtained (%)
C2.21 72.5 with Axial scan on the nozzle side of the IWC-2500-4 Ultrasonic weld is not possible and the weld (b) technique geometry limits access for O and 45
{UT) degree scan angles.
C2.21 Axial scan on the nozzle side of the IWC-2500-4 72.5 with UT weld is not possible and the weld (b) geometry limits access for O and 45 degree scan angles.
31.6 with UT Axial scan on the nozzle side of the C2.21 62.8 with weld is not possible and insulation IWC-2500-4 magnetic brackets obstruct some of the scan (a) particle area for all angles and the surface technique (MT) exam.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 3 of 11 Safety lniection Boric Acid Tank Nozzle Welds SI-TK-2-N-3 and SI-TK-2-N-4 SI-TK-2-N-3 and SI-TK-2-N-4 are shop welds joining the forged carbon steel nozzles to the top and bottom carbon steel hemispherical vessel heads of the safety injection boric acid tank. The inside of the vessel is clad in stainless steel. The nozzles are "set-in" design with large external reinforcement to achieve the design transition profile. This configuration is shown in ASME Section XI as Figure IWC-2500-4 (b). These nozzles have a nominal pipe size of six inches.
The limitation of examination volume was experienced when using the ultrasonic technique. Scans were performed with 0, 45, and 60-degree transducers. The 0 degree is a single scan and is not included in ASME code coverage calculations. For the 45 and 60-degree (shear wave) transducers, scans were performed in four directions. Two scans (scan 1 and 2) are perpendicular and two (scan 3 and 4) are near parallel to the weld bead direction. This results in a total of nine potential scans. Figure 1 shows the shear wave scan directions where exam coverage was possible. Figure 1 is a photo of SI-TK-2-N-4.
Scan 1 Figure 1: Ultrasonic Scan Directions.
For this weld, examination coverage was reduced due to the configuration of the nozzle weld. A cross section sketch of the weld joint is presented in Figure 2. Exams can only be performed from the vessel head side of the weld joint. This removes the ability to perform scan 2 for both the 45 and 60 degree transducers. The 0-degree (straight beam) exam was limited by the location of the weld over top of the desired exam coverage volume. Also, for the 45-degree scan 1, the approach towards the exam area is limited by the weld bead which reduces coverage on the far side of the exam area. This limitation is shown in Figure 2 as the triangle on the left side of the coverage area.
Scanning with an additional angle would not have obtained additional coverage.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 4 of 11 For weld SI-TK-2-N-4, the stainless cladding applied on the inside surface was of a smooth enough condition to interrogate the 45 and 60 degree scan 2 direction using the reflection on the inner surface of the vessel head (see Figure 3). This offers improved coverage and is not used for the ASME code coverage calculation. Notes from the NOE level 3 at the time indicate that this same consideration was evaluated during performance of the exam for the SI-TK-N-3 weld, but that the clad surface of that nozzle was not considered smooth enough for the additional coverage.
Ultrasonic examination coverage of SI-TK-2-N-3 is limited as noted in Table 2, and coverage of SI-TK-2-N-4 is limited as noted in Table 3. Note that additional coverage Note that the Total Coverage indicated in both tables represents additional coverage that is not included in ASME code coverage calculations. The required surface examination performed on both nozzle welds was completed without limitation. The volumetric and surface examinations found no recordable indications.
.,J N t
~
NC '(S* CO"E.A.A4l11. -
bt,t~e,,,o,.. 1.
Figure 2: Sketch of weld configuration.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 5 of 11
-,J N I Figure 3: Reflected wave exam of scan 2 on SI-TK-2-N-4 T: bl 2 Wi Id SI TK 2 N 3 E a e e
xamma ton f
C overa -:ie D t "/
e a,s Exam Beam Direction Code Limitation - clarification Angle Coverage (%)
(degrees) 0 NIA 10 Design and weld reinforcement interfere 45 I (from head side) 80 Configuration - weld location limits approach 45 2 (from nozzle side) 0 Physical configuration prevents scan 45 3 (clockwise) 100 None 45 4 (counterclockwise) 100 None 60 1 (from head side) 100 None 60 2 (from nozzle side) 0 Physical configuration prevents scan 60 3 (clockwise) 100 None 60 4 (counterclockwise) 100 None ASME Cumulative Coverage 72.5 The 0-degree scan is not included in code credited coverage calculations.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 6 of 11 T. bl 3 Wi Id SI TK 2 N 4 E
. t" C
a e e
xamma,on overa9e D t *1 e aJS Exam Beam Direction Code Total Limitation - clarification Angle Coverage Coverage (degrees)
(%)
(%)
0 NIA 10 Design and weld reinforcement interfere 45 I (from head side) 80 80 Configuration - weld location limits annroach 45 2 (from nozzle side) 0 100 Coverage attained using bounce from inner diameter (ID) 45 3 (clockwise) 100 100 None 45 4 (counterclockwise) 100 100 None 60 I (from head side) 100 100 None 60 2 (from nozzle side) 0 100 Coverage attained using bounce from ID 60 3 (clockwise) 100 100 None 60 4 (counterclockwise) 100 100 None ASME Cumulative Coverage:
72.5 The 0 degree and reflected wave exams are not included in code credited coverage calculations.
'~" Steam Generator Feedwater Inlet Nozzle to Vessel Weld RC-E-1A-N-09 RC-E-1A-N-09 is a shop weld joining the forged carbon steel feedwater nozzle to the forged 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 38 inches, and a material thickness of approximately 4.21 inches. This configuration is shown in ASME Section XI as Figure IWC-2500-4 (a).
The examination limitation was experienced during both the volumetric exam using the ultrasonic technique and the surface exam using the magnetic particle technique. For the volumetric exam, scans are performed with 0, 45, and 60-degree transducers. The 0 degree is a single scan and is not included in ASME code coverage calculations per 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 (scan 3 and 4) are near parallel to the weld bead direction. This results in a total of nine potential scans.
For the volumetric exam, the axial scan cannot be performed on the nozzle side of the weld due to the nozzle geometry. For the surface exam, a probe with adjustable spacing from 4 to 8 inches was used to maximize coverage. The exam is performed in at least two directions approximately 90 degrees from each other across the weld.
The exam coverage was limited for both surface and volumetric exams by a physical obstruction with nearby insulation supports. These supports are metal bands installed around the steam generator body. Figure 4 shows the nozzle and the angle iron supports above and below it. This obstruction impeded coverage at the top and the bottom of the weld for both the volumetric and surface exams. Due to the additional space needed with increasing examination angle in the ultrasonic technique, the
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 7 of 11 coverage obtained is greater at lesser exam transducer angles. Figure 5 shows the coverage area for each exam angle.
For the magnetic particle technique, Figure 6 shows the coverage area. See Table 4 for a summary of the coverage obtained by both exam methods.
Steam generator vessel wall
-.d',*Jl - '{j Weld location Feedwater piping Figure 4: RC-E-1 A-N-09 nozzle and obstructing angle iron supports.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 8 of 11 45° 60° COMPONENT ID:
We ld Width = 1.5 RC - E-lA-N- 9 Exam Volume Width 2.0" Exam Surface 2.0" T = 4.2 1"'
z 0
i== 5 l/)
z 0:::
0 0:::
0:::
.L Figure 5: Ultrasonic Technique Exam Coverage Weld Width: 1.5" 62.83% Coverage
~,38~0 025.0 Exam Width 2.5"
~-
Figure 6: Magnetic Particle Technique Exam Coverage s::
- a
- a 0
- o z
U)
C
~
-i 0 z
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 9 of 11 T bl 4 VI a e o ume nc t. C overaqe s ummarv o f RC E 1A N 9 Exam Code Angle Beam Direction Examined Limitation - clarification (degrees)
(%)
0 NIA 70.07 Obstruction 45 All 39.11 Geometry prevents one scan and obstruction 60 All 24.15 Geometry prevents one scan and obstruction ASME Cumulative Coverage 31.63 The 0-degree scan is not included in code credited coverage calculations.
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign of the supports installed around the steam generator body and redesign of the safety injection boric acid tank nozzles. Replacement of components to obtain the required inspection 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 approximately 40 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 fitment issues upon replacement. This work would be required within the steam generator cubicle where radiological dose rates are elevated.
If fitment issues are not encountered, the estimated man hours in the field for scaffold and insulation work is 936 hours0.0108 days <br />0.26 hours <br />0.00155 weeks <br />3.56148e-4 months <br /> with approximately 6.68 REM of radiological dose. This is in addition to the time and exposure of the examiners. This work would provide additional coverage but still may not yield greater than 90% required for the volumetric exam. Discussion with insulators revealed a high likelihood that dose rates will increase due to adjustments needed during reinstallation of the band supports. It is likely that some insulation panels would have to be removed and reinstalled multiple times for fitment.
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.
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 10 of 11
6. Proposed Alternative and Basis for Use
Safety lniection Boric Acid Tank Nozzle Welds SI-TK-2-N-3 and SI-TK-2-N-4 The proposed alternative to the examination volume requirement specified in Figure IWC-2500-4(b) is performing the ultrasonic examination to the maximum extent practicable and crediting leakage walkdowns.
Most of the code coverage limitation is the result of the axial scan from the nozzle side of the weld not being possible due to geometry. Also, a portion of the 45-degree axial scan volume was limited due to interference with the weld bead before reaching the entire coverage area. The area that could not be examined with the 45 degree axial scan was not ID connected. It is likely that an inservice flaw would be planar in nature and ID connected, which is likely to be detected by the exam volume covered. The entire required examination volume was examined in three scan directions with 60-degree angle beams and at least 80% of the required examination volume was examined in three scan directions with 45-degree angle beams. No recordable indications were found.
This tank is in the primary auxiliary 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 monthly during walkdowns by system engineering. Leakage resulting from degradation would be discovered within a reasonable amount of time.
The surface exam was performed using magnetic particle technique and did not have a coverage limitation. No indications were found.
The VT-2 and surface examinations, along with the UT examination coverage detailed above provide reasonable assurance of continued reliability of these welds. A review of previous examinations showed no history of indications within these welds. Condition monitoring already in place would detect a through wall leak within a reasonable amount of time.
Also, in the current fifth 10-year ISi interval a risk-informed process has been implemented using Code Case N-716-1, "Alternative Classification and Examination Requirements." These safety injection tank boric acid welds have been determined to be low safety significant and no longer require volumetric or surface examination.
'~" Steam Generator Feedwater Inlet Nozzle to Vessel Weld RC-E-1A-N-09 The proposed alternative to the examination volume requirement specified in Figure IWC-2500-4(a) is performing the ultrasonic and magnetic particle examinations to the maximum extent practicable, continuing leakage walkdowns, and monitoring for leakage in accordance with plant technical specifications. The UT examination covered 31.6 percent of the required volume, and the MT examination covered 62.8 percent of the
10 CFR 50.55a Request Number: 1-TYP-4-C2.21-1, Revision 0 Page 11 of 11 required area. No recordable indications were found for either the volumetric or surface exam areas achieved.
The steam generator is located in the primary 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 Beaver Valley 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 examinations, 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 fourth 10-year inservice inspection interval at BVPS-1, which began April 1, 2008 and ended August 28, 2018.
L-19-106 Beaver Valley Power Station, Unit No. 1 10 CFR 50.55a Request 1-TYP-4-RA-1, Revision 0 (6 pages follow)
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 1 of 6 Relief Request in Accordance with 10 CFR 50.55a(g)(5)(iii)
--lnservice Inspection Impracticality--
- 1. ASME Code Components Affected Table 1 contains a listing of seven class 1 and 2, category R-A, item number R1.11 piping welds.
- 2. Applicable Code Edjtjon 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-1 fourth interval.
3. Applicable Code Requirement
The examination requirements for Class 1 and 2 piping welds at BVPS-1 for the fourth interval are from a risk-informed inservice inspection (RI-ISi) program approved by the NRG (Accession ML110630403) and included as a reference to this document. 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 lnservice 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 IWB-2500-8, "Similar and Dissimilar Metal Welds in Components, Nozzles, and Piping,"
for Class 1, and Figure IWC-2500-7 "Welds in Piping" for Class 2 circumferential piping welds.
This program divided piping into segments and requires a complete volumetric exam on one weld within each high safety significant (HSS) segment. When an exam has limited exam coverage, the program requires examining other weld(s) in the segment if available.
ASME Code Case N-460, "Alternative Examination Coverage for Class 1 and Class 2 Welds,"
states, in part, 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 in coverage is less than 10 percent(%) (greater than 90% coverage is obtained).
4. Impracticality of Compliance
The examination volume requirement specified in Figure IWB-2500-8 and IWC-2500-7 for the noted welds has been determined to be impractical. When examined, these weld joints could not be axially scanned in one direction. Within these RI-ISi segments there were only pipe-to-component selections available, which contains geometry that prevents the component side axial scans. Per the RI-ISi program, when an examination yields a limited coverage volume, another weld in the segment is also examined if available. For three of the four segments in this relief request, another weld joint was available; however, it also yielded limited exam coverage.
Table 1 provides a summary of details for each weld and the cause of the limited exam volume.
Additional details on the RI-ISi segments are provided below.
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 2 of 6 Table 1: S fl.
IE Code Item Risk Component ASME Informed Configuration Material ID Class Number Segment Valve-ASTM-A-182 Pipe to valve F304 RH-1-3-F-04 1
Rl.11 (forged stainless steel) butt weld Pipe-A351 CF8M (cast stainless steel)
RH-002 Valve-ASTM-A-182 Pipe to valve F304 RH-1-3-F-0S 1
Rl.11 (forged stainless steel) butt weld Pipe-A351 CF8M (cast stainless steel)
Pump volute-A351 Pump outlet to CF8M RH-4-1-F-01 2
Rl.11 pipe reducer (cast stainless steel) butt weld Reducer-A351 CF8M RH-005 (cast stainless steel)
Valve to pipe Valve-A351 CF8M RH-4-1-F-02 2
Rl.11 reducer butt (cast stainless steel) weld Reducer-A351 CF8M (cast stainless steel)
Pump volute-A351 Pump outlet to CF8M RH-5-1-F-01 2
Rl.11 pipe reducer (cast stainless steel) butt weld Reducer-A351 CF8M RH-006 (cast stainless steel)
Valve to pipe Valve-A351 CF8M RH-5-1-F-02 2
Rl.11 reducer butt (cast stainless steel) weld Reducer-A351 CF8M (cast stainless steel)
Valve-A351 CF8 QS-9-1-F-01 2
Rl.11 QS-042 Pipe to Valve (cast stainless steel) butt weld Pipe-A351 CF8M (cast stainless steel)
Pipe Size ASME Code Best-Effort (inches)-
ASME Code Figure Coverage Impracticality Coverage (%)
Schedule
(%)14-160 IWB-2500-8 so 80 Single-sided exam 14-160 IWB-2500-8 so so Single-sided exam 8-40S so 80 Single-sided IWC-2500-7(a) exam 10-40S IWC-2500-7(a) so 80 Single-sided exam 8-40S IWC-2500-7{a) so 80 Single-sided exam 10-40S so 80 Single-sided IWC-2500-7(a) exam 6-10S IWC-2500-7{a) so 55 Single-sided exam
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 3 of 6 Risk-Informed Segment RH-002 RH-002 is a short, straight segment of 14-inch nominal schedule 160 ASME Class 1 piping that connects two valves. This segment is located in the Residual Heat Removal system between isolation valves before the pumps. The material is stainless steel with cast piping and forged valves. In this segment, the only eligible welds for examination were the pipe to valve welds at each end of the piping, RH-1-3-F-04 and RH-1-3-F-05.
These welds are circumferential butt welds. Both welds were volumetrically examined using a procedure based on PDI-UT-2 and found to have limited exam coverage due to the valve body geometry preventing one axial scan. A refracted longitudinal (RL) wave exam was used as a supplemental axial scan to improve examination coverage.
The materials of construction reduce the code-credited coverage due to ultrasound attenuation. When the examiner determined that further coverage was obtained than what is qualified in the procedure, this is reported as total coverage in the table below.
Ultrasonic examination coverage of welds within segment RH-002 is limited as noted in Table 2. The volumetric examination coverage attained found no recordable indications.
T, bl 2 S a e eqmen xamma ton eats.
t RH 002 E
. f D t *1 Weld Number Exam angles Qualified%
Total%
Exam notes used Examined Examined RH-1-3-F-04 45 and 45RL 50 80 Single sided exam.
RH-1-3-F-05 45, 60, and 60RL 50 50 Single sided exam.
- 1) The NOE report indicates that a 60-degree angle scan was also performed. Only one angle is used in coverage calculations.
Risk-Informed Segments RH-005 and RH-006 RH-005 and RH-006 are short segments each consisting of an 8-inch to 10-inch schedule 40S ASME Class 2 expander with a circumferential butt weld at each end. On the 8-inch end the expander is welded to the outlet of a residual heat removal pump and the 10-inch end is welded directly to a discharge check valve. The material of the expander, pump nozzle, and check valve is cast austenitic stainless steel. Due to the limitations of exam coverage, both segments examined the weld at each end of the expander for a total of four exams in two segments. No further weld locations were available to examine.
Both welds were volumetrically examined using a procedure based on PDI-UT-2 and found to have limited exam coverage due to the component geometry preventing one axial scan. Additionally, a 70-degree shear wave angle was used as a supplemental axial scan to improve the best-effort examination coverage.
The materials of construction further reduce the possible code-credited coverage due to ultrasound attenuation. However, the examiner determined that further coverage was
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 4 of 6 obtained than what is qualified in the procedure; this coverage was reported as total coverage in Tables 3 and 4.
Ultrasonic examination coverage of both welds within segments RH-005 and RH-006 is limited as noted in Tables 3 and 4. The volumetric examination coverage attained found no recordable indications.
T, bl 3 S a e eqmen xamma,on e a,s.
t RH 005E
. f D t "I Weld Number Exam angles Qualified%
Total%
Exam notes used Examined Examined RH-4-1-F-0l 45 and 70 50 80 Single sided exam.
RH-4-1-F-02 45 and 70 50 80 Single sided exam.
T, bl 4 S a e egmen t RH 006 E
. f D t "/
xamma,on e a,s.
Weld Number Exam angles Qualified%
Total%
Exam notes used Examined Examined RH-5-1-F-0l 45 and 70 50 80 Single sided exam.
RH-5-1-F-02 45 and 70 50 80 Single sided exam.
Risk Informed Segment QS-042 QS-042 is a short segment connecting a valve to the refueling water storage tank. This segment consists of a single circumferential butt weld joining a weld neck flange to the tank nozzle. The nominal pipe size for this connection is 6 inch, schedule 1 OS. The material of the nozzle and weld neck flange are cast austenitic stainless steel. There is only one weld in this segment; therefore, no additional weld locations were available to examine.
This weld was volumetrically examined using a FENOC procedure based on PDI-UT-2 and found to have limited exam coverage. The physical configuration of the weld neck flange prohibits any ultrasonic coverage from the flange side of the weld. This prevents one axial scan. Additionally, a 70-degree shear wave angle was used as a supplemental axial scan to improve the examination coverage.
The materials of construction further reduce the possible code-credited coverage due to ultrasound attenuation. However, the examiner determined that further coverage was obtained than what is qualified in the procedure; this coverage was reported as total coverage in Table 5.
Ultrasonic examination coverage of QS-9-1-F-01 within segment QS-042 is limited as noted in Table 5. The volumetric examination coverage attained found no recordable indications.
T, bl 5 S a e egmen
. f D t *1 xamma,on e a,s.
tQS 042E Weld Number Exam angles Qualified%
Total%
Exam notes used Examined Examined QS-9-1-F-0 I 45, 60 and 70 50 55 Single sided exam.
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 5 of 6
5. Burden Caused by Compliance
To obtain the specified volumetric examination volume would require redesign and replacement of the piping segments and components in Section 1 of this request.
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 is performing the ultrasonic examination to the maximum extent practicable. This, along with monitoring for leakage via the VT-2 examinations and engineering walkdowns provides acceptable means to ensure the continued reliability of these piping segments and prompt identification of problems.
The FENOC RI-ISi program requires complete volumetric examination coverage of one weld within each HSS segment listed in Table 1. The postulated damage mechanism for these segments was thermal fatigue. For each of these segments there were no welds to select that would not result in a single sided axial exam, 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, seven limited coverage exams were performed in an attempt to fully examine one weld in each of the four segments. For all seven exams, no recordable indications were found.
Segment QS-042 is located on the refueling water storage tank, which is accessible during normal operation. Segments RH-002, RH-005, and RH-006 are located inside the reactor containment building and accessible during outages. Per ASME code category C-H, Class 2 segments receive a VT-2 exam for leakage at operating pressure once per period (40 months). Per ASME code category B-P, Class 1 segments receive a VT-2 exam for leakage at operating pressure each outage during startup. The refueling water storage tank is also surveilled during walkdowns by system engineering. For the segments in containment, leakage rates within containment are monitored and sources identified as part of compliance to plant technical specifications. Also, for the Class 2 segments in containment, any leakage would be noted during Class 1 pressure test walkdowns performed after each outage during startup. Therefore, leakage resulting from degradation would be discovered within a reasonable amount of time.
Therefore, in accordance with 10 CFR 50.55a(g)(5)(iii), FE NOC has determined that the required examination coverage for these welds is impractical and requests that the proposed examinations be considered an acceptable alternative to the examination coverage requirement.
7. Duration of Proposed Alternative
The proposed alternative is requested for the fourth 10-year inservice inspection interval at BVPS-1, which began April 1, 2008 and ended August 28, 2018.
10 CFR 50.55a Request Number: 1-TYP-4-RA-1, Revision 0 Page 6 of 6
- a. References NRC letter dated March 23, 2011, Beaver Valley Power Station, Unit Nos. 1 and 2-Relief Request RI-ISl-1 and RI-ISl-2 Regarding the Fourth and Third Risk-Informed lnservice Inspection Intervals (TAC Nos. ME4104 and ME4105), (ML110630403)