L-2025-147, Fifth 10-Year Inservice Inspection (ISI) Interval - Relief Request (RR) 3, Intake Cooling Water Piping Evaluation Using ASME Code Case N-513-5
| ML25226A132 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 08/14/2025 |
| From: | Mack K Florida Power & Light Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-2025-147 | |
| Download: ML25226A132 (1) | |
Text
l=PL.
ATTN : Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 RE:
St. Lucie Nuclear Plant Unit 2 Docket No. 50-389 Renewed Facility Operating License NPF-16 August 14, 2025 L-2025-147 10 CFR 50.55a(z)(2)
St. Lucie Unit 2 Fifth 10-Year lnservice Inspection (ISi) Interval - Relief Request (RR) #3, Intake Cooling Water Piping Evaluation Using ASME Code Case N-513-5
- 1.
Regulatory Guide 1.147, lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 21, March 2024 (ADAMS Accession No. ML23291A003)
- 2.
U.S. Nuclear Regulatory Commission letter dated February 3, 2021, St. Lucie Plant, Unit No. 2 -
Approval of Alternative,to Use ASM E Code Case N-513-4 for Alternate Repair of Intake Cooling Water System (EPID L-2020-LLR-0021) (ADAMS Accession No. ML20329A402)
Pursuant to 10 CFR 50.55a(z)(2), Florida Power & Light Company (FPL) requests for St. Lucie Nuclear Plant, Unit 2 (St. Lucie Unit 2), relief from the inservice inspection (ISi) requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section XI (ASME Section XI Code), on the basis that compliance would create a hardship or unusual difficulty without a compensating increase in quality and safety. Specifically, relief is requested for the use of ASME Code Case N-513-5, as conditionally approved in Reference 1, for the evaluation of an Intake Cooling Water (ICW) flaw in a flange transition region, a location not explicitly addressed by the Code Case. Code Case N-513-5 allows temporary acceptance of flaws in moderate energy Class 2 or 3 piping supplemented by augmented examinations.
The relief request also includes an alternative method for evaluating the ICW wall condition. In Reference 2, FPL received ASME Code relief for a ICW piping flaw until eventual replacement of the affected elbow.
The enclosure to this letter provides FPL's evaluation of the proposed relief request which demonstrates that the structural integrity and functional requirements of the affected ICW piping will be maintained during the period of relief. Attachment 1 to the enclosure provides Saint Lucie NDE Report PSL-UTT-017. provides Structural Integrity Associates, Inc., calculation 2552494.301.
FPL requests approval of the relief request by August 19, 2025, in order to avert Technical Specification-related operational limitations and surveillances that could potentially challenge unit operation. The proposed relief would remain in effect until St. Lucie Unit 2 completion of the spring 2026 refueling outage.
This letter contains no new regulatory commitments.
Should you have any questions regarding this submission, please contact Ms. Maribel Valdez, Fleet Licensing Manager, at 561-904-5164.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on the 14th day of August 2025.
~L~
Ken
.~
Director, Regulatory Affairs Florida Power & Light Company Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Enclosure Attachments L-2025-147 10 CFR 50.55a(z)(2)
- 1.
Saint Lucie NOE Report #PSL-UTT-017, Flow-Accelerated Corrosion (FAC) Ultrasonic Thickness Report
- 2.
Structural Integrity Associates, Inc., Calculation 2552494.301, St. Lucie Flange Wall Thinning Evaluation cc:
USNRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant, Units 1 and 2 USNRC Senior Resident Inspector, St. Lucie Nuclear Plant, Units 1 and 2 Mr. Clark Eldredge, Florida Department of Health
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 1 of 8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone
- 1. ASME CODE COMPONENT(S) AFFECTED:
Component:
St. Lucie Unit 2 Intake Cooling Water (ICW) Piping Code Class:
Class 3
Reference:
ASME Section XI Code Case N-513-5
==
Description:==
ICW Pump Discharge Piping Welded Neck Flange Size:
Piping Diameter - 36 inches Nominal Thickness - 0.375 inches Design Conditions:
Temperature - 125°F Pressure - 90 psig Operating Temperature (Max) - 95°F Conditions:
Pressure (Max) - 90 psig Materials:
Cement lined, Carbon Steel; SA-106 Grade B
- 2. APPLICABLE CODE EDITION AND ADDENDA:
St. Lucie Unit 2 (PSL2) is in its 5th ASME Section XI Code Interval, which began on August 81h, 2023; and ends on August 7th, 2033. The current applicable edition of ASME Section XI is the 2019 Edition with no Addenda.
The code of record for the PSL2 ICW system is ASME Section Ill, 1971 Edition with Addenda through Summer 1973.
- 3. APPLICABLE CODE REQUIREMENT:
In accordance with ASME Code Section XI, 2019 Edition, subparagraph IWD-3120(b), flaws in ASME Code Class components which do not meet the standards shall be subjected to supplemental examination, orto a repair/replacement activity. In regard to the flaw analysis, IWD-3500, "Acceptance Standards" for Class 3 components, states that the requirements of IWC-3500, "Acceptance Standards" for Class 2 components, may be used.
Additionally, IWA-4000 describes the repair/replacement activities to correct an unacceptable flaw.
Discovery of an area below the design minimum wall thickness in the structural portion of an ASME Code Class 1, 2, or 3 component is direct evidence of a flaw in the component.
The ASME Section XI Code does not include analytical evaluation criteria for acceptance of through-wall flaws in pressure retaining base material of ferritic pipe or fittings. Code Case N-513-5, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, Division 1," which has been conditionally approved by the U.S. Nuclear Regulatory Commission (NRC) in
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 2 of8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1,"
Revision 21, provides analytical evaluation rules for temporary acceptance of flaws in piping. Code Case N-513-5, however, does not address the flange transition region of the flange past...J Rt from the centerline of the weld and up into the transition of the flange where the bolt holes are located.
Relief is requested from the requirements of ASME Section XI, IWA-4000, so that code repair or replacement of the non-planar flaws, located at the flange transition region of the flange neck past.../ Rt from the centerline of the weld and up into the transition of the flange where the bolt holes are located, may be deferred until the conclusion of the next PSL2 refueling outage which is currently scheduled to start in April 2026. During the period of relief, FPL will apply Code Case N-513-5 along with ASME Section Ill, NB-3200, for evaluation of the area past.../Rt from the centerline of the weld and up into the transition of the flange, as described in Section 5.0 of this relief request.
- 4.
REASON FOR REQUEST:
Florida Power & Light Company (FPL) is requesting a proposed alternative from the requirement to perform repair/replacement activities for the degraded flange, which has a through-wall flaw.
On August 6, 2025, a through-wall flaw was discovered in the PSL2 Intake Cooling Water (ICW) system.
The flaw is located on the 36-inch weld neck flange, located in line 1-36-CW-16 (Figure 1). During the period of discovery, it was identified that the flaw and any flaw growth will be outside the scope of ASME Code Case N-513-5 since the location of the flaw is in the transition zone of the flange neck to the flange plate where the bolt holes are located. ASME Code Case N-513-5 is conditionally approved by the NRC for generic use and provides criteria to allow temporary acceptance of flaws, including through-wall flaws in moderate energy Class 2 or 3 piping without performing repair or replacement activities in accordance with ASME Code Section XI, Article IWA-4000. ASME Code Case N-513-5 includes guidance for evaluating flaws in pipe fittings including flanges. However, it does not address the evaluation that extends past the.../ Rt from the centerline of the weld and up into the transition of the flange where the bolt holes are located.
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 3 of8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone 4.1 Flaw characterization:
The identified flaw was Top Dead Center (TDC), measured 1.5 inches circumferentially and 1-inch axially and was located within the weld neck of the flange, bordering up to the flange plate (See Figure 2). The location is approximately 25 ft from the 2A ICW pump.
Ultrasonic thickness (UT) examinations of the flange on August 9, 2025 (Attachment 1) identified that no value outside of the flaw location was below the design minimum wall thickness, tm;n, of 0.175 inches.
The average wall thickness of all the NOE data is 0.666-inches, showing significant wall thickness for the flange neck. It is not possible to identify the exact cause of the through wall leak without removing the system from service and accessing the interior of the piping for examination. Due to the location of the flaw and the specific system, it is speculated that the most likely cause of the flaw is general corrosion resulting from localized degradation of the internal concrete lining of the pipe.
Figure 2 - As found flaw.
A Finite Element Analysis (FEA) was completed to ensure the component is structurally stable and not subject to catastrophic failure. Per Section 5.0 "Augmented Examinations" of the N-513-5 Code Case and the Regulatory Guide 1.147 "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1" Conditions, five other susceptible locations will be chosen for examination within 30 days of when the first flaw was detected. Consistent with Code Case N-513-5 requirements, the flaw on the flange is being monitored daily to confirm analysis conditions while recurring re-examinations will be performed to identify any flaw growth and to establish the time at which the detected flaw will reach the allowable size.
4.2 Leakage
Leakage has been mitigated with a temporary plug (Figure 3). The plug has reduced the leak rate to between zero and 10 gpm. This level of leakage (max 10 gpm) has no risk of challenging the system margin of 1580 gpm allowed to maintain safety operation. Additionally, any leakage will drain into the intake well (ocean) and is not a risk for spray or flooding. Without the plug installed the system would experience a conservatively calculated leakage rate based on a 2-inch diameter opening of 796.5 gpm, which is still under the system margin of 1580 gpm allowed to maintain its safety function by 2 times.
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 4 of8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone Figure 3 - Plugged condition 4.3 Hardship and Unusual Difficulty for ICW Line Code Repair Deferral:
The proposed code repair requires securing one ICW train for a minimum of four consecutive days to drain piping, remove an elbow, and perform internal repair. The repair would require manual entry and crawl-thru of several feet of piping in high temperatures to perform the repair. Extended single-train operation also presents significant operational hardships that could compromise plant safety margins, reliable power generation, and regional grid stability during peak demand conditions. This includes challenges associated with responding to abnormal conditions that would otherwise be manageable, as well as seasonal specific challenges detailed below.
Containment Temperature Maintenance The 2A ICW pump was briefly isolated on August 3th for initial identification of the flaw, and again on August 9th for ultrasonic characterization of the flaw. During each isolation period, the containment average air temperature increased by degrees within a 60 to 90 minute period, with a peak containment average air-temperature increase from112°F to 115°F. Prolonged operation with a single ICW train could result in challenging the LCO 3.6.5 containment average air temperature limit of 120°F.
Critical Vulnerability During Peak Intake Intrusion Season:
This timeframe represents the highest risk period for fibrous algae intrusions in South Florida waters.
While multiple defense systems exist, effective mitigation relies heavily on the ability to backwash Turbine Cooling Water (TCW) strainers when differential pressure becomes excessive. This backwash process requires both ICW trains operational to enable heat exchanger cross-tie capability. Single-train operation eliminates this critical cleaning capability, creating high probability of:
Forced unit shutdown due to unacceptable secondary plant temperatures Extended outage duration if intrusion events overwhelm remaining filtration capacity Inability to maintain adequate primary and secondary cooling during the most challenging environmental conditions
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 5 of 8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone Thermal Performance Challenges During Peak Ocean Temperature Conditions:
Current ocean temperatures are at elevated seasonal levels, placing maximum thermal stress on the ICW system. The ICW system serves as the ultimate heat sink for both safety-related Component Cooling Water (CCW) loads-including containment fan coolers and critical plant components-and non-safety related turbine building cooling loads. Operating on a single ICW train during these thermal conditions severely reduces the system's ability to accommodate any additional temperature increases, creating risk of:
Containment air temperature challenges that could require power reductions or unit shutdown Secondary plant thermal limitations impacting generation capacity Reduced safety margins for CCW system performance Grid Reliability Impact During Critical Demand Period:
Regional electrical demand currently operates at higher than normal levels due to extreme summer conditions throughout Florida. As such, any unplanned unit shutdown during this period would:
Compromise regional grid stability during peak demand Force reliance on less efficient peaking units, impacting system reliability Create potential public health and safety concerns due to reduced electrical supply during extreme heat conditions Result in significant economic impact to ratepayers through higher-cost replacement power Compounding Risk Factors:
The convergence of multiple risk factors during this period creates a compounding effect where the probability and consequences of plant shutdown are significantly elevated:
Seasonal thermal stress + single-train operation + peak intrusion season + maximum grid demand Limited ability to respond to transient conditions that would normally be manageable Potential cascade effects if multiple challenges occur simultaneously Additionally, plant shutdown activities result in additional dose, transients, and plant risk that would be inappropriate when a degraded condition is demonstrated to retain adequate margin to complete the component's function. Additionally, this relief request and analysis; follows and treats the analysis with all the requirements in Code Case N-513-5, with the exception of the three-dimensional (3-D) finite element model (FEM), as described in Section 5 below. Therefore, if the flaw was located within the
- /Rt from the centerline of the weld, the Code Case would allow for continual operation until the next refueling outage.
The use of an acceptable alternative analysis method in lieu of immediate action for a degraded condition will allow FPL time for safe and orderly long-term repair or replacement actions.
- 5.
PROPOSED ALTERNATIVE AND BASIS FOR USE:
FPL is requesting authorization to apply ASME Code Case N-513-5 for the evaluation of the subject ICW flaw, with the exception that the ASME Section Ill 2007 Edition, Design by Analysis, approach in section ASME Section Ill, paragraph NB-3200, was employed to evaluate the non-uniform wall thickness and local thinning of the flange. The NB-3200 FEA approach to evaluate the part of the component past ;/Rt from the centerline of the weld and up into the transition of the flange is outside
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 6 of8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone the scope of the Code Case due to the calculation of stress intensity factors for complex geometry being unsuitable for simple hand calculations.
Instead, a detailed three-dimensional (3-D) finite element model (FEM) was utilized in the evaluation to calculate the stress field associated with the non-uniform wall thickness (SIA Calculation 2552494.301, Attachment 2).
Given that there is no value outside of the flaw location that is below the design minimum wall thickness tmin identified, the primary stress design criteria for Service Level A (Normal) and Level B (Upset) conditions are based on the limit load design criteria of Subparagraph NB-3228.1, "Limit Analysis." NB-3228.1 states:
"The limits on General Membrane Stress Intensity (NB-3221. 1), Local Membrane Stress Intensity (NB-3221.2), and Primary Membrane Plus Primary Bending Stress Intensity (NB-3221.3) need not be satisfied at a specific location if it can be shown by limit analysis that the specified loadings do not exceed two-thirds of the lower bound collapse load. The yield strength to be used in these calculations is 1. 5Sm."
The allowable Stress, S, is used instead of the Class 1 Design Stress Intensity, Sm. As a result, the S value is substituted for the Sm, in regard to establishing the yield stress defined above. This is consistent with the design rules, as the yield stress defined here is the equivalent of the Local Primary Membrane Stress, which uses an allowable stress of 1.5Sm for Class 1 components, or 1.5S for Class 2 and 3 and 831.1 components.
Subparagraph NB-3213.28, "Limit Analysis - Collapse Load" states:
"The methods of limit analysis are used to compute the maximum load that a structure assumed to be made of ideally plastic material can carry. At this load, which is termed the collapse load, the deformations of the structure increase without bound."
A total load of 1 /(2/3) = 150% of the applied maximum loads on the degraded section of pipe must be sustained without any portion of the pipe plastically collapsing (i.e., the membrane stress across an entire section for a given location does not exceed the defined yield stress of 1.5S).
The primary stress design criteria Service Level D (Faulted) conditions will be based on the limit load design criteria of Appendix F, F-1200(a), and will be based on the ASME Code, Section Ill, Appendix F, Subparagraph F-1341.3. F-1341.3 states:
"Static or equivalent static loads shall not exceed 90% of the limit analysis collapse load using a yield stress which is the lesser of 2.3Sm and 0. 7Su... "
A total load of 1/0.9 = 111.1 % of the applied faulted loads on the degraded section of pipe must be sustained without any portion of the pipe plastically collapsing (i.e., the membrane stress across an entire section for a given location does not exceed the defined yield stress of 2.3S or 0.7Su).
To that end, the 3-D FEM of the degraded piping and the appropriate maximum Normal/Upset and Faulted loads (internal pressure and piping moments) was evaluated. The total load, as a percentage of nominal load has been compared to the required 150% of the Service Level A/8 (Normal/Upset) loads and 111.1 % of the Service Level D (Faulted) loads as defined in the criteria identified above.
Based on the above criteria the flange meets the limit load design criteria outlined in Subparagraph NB-3228.1, "Limit Analysis" with a conservatively extended hole size of 14-inch (circumferential) x 5-inch (axial).
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 7 of 8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone Consistent with the requirements of ASME Code Case N-513-5, Section 2, the following compensatory actions shall be performed until such time that the flaw is repaired or piping section is replaced.
(a) Frequent periodic examinations of no more than 30-day Intervals shall be used to determine lfflaws are growing and to establish the time, at which the detected flaw will reach the allowable size. This may be extended to 90 days if supported by a flaw growth evaluation per N-513-5 paragraph 2(e).
(b) For through-wall leaking flaws, leakage shall be monitored daily to confirm the analysis conditions used in the evaluation remain valid.
(c) If examinations and re-analysis of the FEA reveal the flaw growth rate to be unacceptable, repair/replacement activity shall be performed.
(d) Repair/replacement activities shall be performed no later than when the predicted flaw size from trending periodic Inspection is expected to exceed the analyzed size of 14-inches (circumferential) x 5-inches (axial), or during the next scheduled refueling outage, whichever occurs first.
Repair/replacement activities shall be in accordance with IWA-4000.
In conclusion, based on the above proposed alternative and the detailed evaluation in Attachment 2, the structural integrity and functional requirements of the pipe will be maintained. The Intake Cooling Water System will continue to be capable of providing required cooling water flow to meet the required cooling margins. There will be no adverse impact on neighboring equipment due to either spray or flooding.
- 6. DURATION OF PROPOSED ALTERNATIVE:
Relief by August 19, 2025, is needed to provide sufficient time, should relief not be granted, to complete the ASME Code-compliant repair and restore 2A ICW train operability prior to expiration of a required diesel generator surveillance on August 28, 2025, and a Risk Informed Completion Time on September 5, 2025. The relief request would remain in effect until completion of the St. Lucie Unit 2 spring 2026 refueling outage scheduled to begin in April 2026.
- 7. PRECEDENTS:
- 1.
U.S. Nuclear Regulatory Commission letter to Duke Energy, "Brunswick Steam Electric Plant, Unit 1 - Proposed Alternative for Acceptance of Through-Wall Flaw In Reducer (EPID L-2025-LLR-0038), dated May 16, 2025 (ADAMS Accession No. ML25135A417).
- 2.
U.S. Nuclear Regulatory Commission letter dated February 3, 2021, St. Lucie Plant, Unit No. 2 -
Approval of Alternative to Use ASME Code Case N-513-4 for Alternate Repair of Intake Cooling Water System (EPID L-2020-LLR-0021) (ADAMS Accession No. ML20329A402)
- 8.
REFERENCES:
- 1.
ASME Boiler and Pressure Vessel Code, Code Case N-513-5, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping and Gate ValvesSection XI, Division 1," April 18, 2018.
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Page 8 of8 Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone
- 2.
ASME Boiler and Pressure Vessel Code, Section Ill, "Rules for Construction of Nuclear Power Plant Components," 2017Edition.
- 3.
ASME Boiler and Pressure Vessel Code,Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," 2019 Edition.
- 4.
Regulatory Guide 1.147, lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1, Revision 21, March 2024 (ADAMS Accession No. ML23291A003)
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone ATTACHMENT 1 SAINT LUCIE NDE REPORT #PSL-UTT-017 FLOW-ACCELERATED CORROSION (FAC) ULTRASONIC THICKNESS REPORT (3 pages follow)
Flow-Accelerated Corrosion (F AC) Ultrasonic Thickness Report NDE Report # PSL-UTT-017 Page 1 of 3 D St. Lucie 1 D Turkey Point 3 D Seabrook ULTRASONIC THICKNESS REPORT
[8J St. Lucie 2 D Turkey Point 4 Procedure: 5.18 Rev. 09 l=PL Component ID: I-36-CW-16 Drawing: 2998-G-125 Sh. CW-F-2 Component Type: Flange Building: Zurn Pit Material: Carbon Steel System: 21, Circ Water, ICW Diameter: 36" Elevation: 14' - O" INSTRUMENT SKETCH Manufacturer:
Olympus Range:
1.00" Notto Scale Upstream Component Valve SB21166 Serial Number:
160480610 Gain:
60 Downstream Component Tee Model:
45MG Velocity:
.2320 Electronic file ID NIA TRANSDUCER
!Manufacturer:
Panametrics Serial No.:
949914
- See Pg 2 and 3 for readings and locations/sketches.
Model:
D791-RM Frequencv:
5MHZDual Size:
0.375"
- of Elements:
2 Procedure 5.18 used as guidance for exam. Readings taken at prepped locations per PSL Cable Length:
6' Cable Tvoe:
RG-174 Engineering around flange neck with unparallel surfaces, due to this component configuration this TEMPERATURE data was obtained as a "best effort" and is intended for informational use only.
Manufacturer:
Fluke Serial Number:
PSL-4450 Component:
87.6 op
!Reference Block: 87 ° F REFERENCE BLOCK Serial Number: 801260 Material:
Steel COUPLANT Type:
Ultragel II Batch:
21L053 CALIBRATION INFORMATION Calibration Thickness 1 Calibration Times Actual Measured 0.250" 0.251" Initial:
1235 0.500" 0.500" Intermediate:
1304 0.750" 0.750" Intermediate:
1.000" 1.001" Intermediate:
1337 Final:
1415 DATA2 Nominal CTnomina1) 0.375 in. Per PSL Engineering View:
D Top [8J Side Previously examined:
0Yes
[8J No Screening (T,creening)
NI A Per PSL Engineering Grid Size:
D l" 02" 04"
[8J n/a - Scan Exam performed from:
[8J OD Orn Minimum Acceptable (Tminimum) 0.175 in. Per PSL Engineering Alpha grid limit: A through A-C Comments I Remarks I Limitations:
Numeric grid limit: 1 through 12 WO# 41027006-02, AR# 02520962 See Readings and drawings on Page 2 and 3.
Minimum Measured (T min meas) 0.575" See comments in above section for limitations.
Minimum Measured (coordinate)
Location 8C Above Screening?
NIA 0Yes 0
No i
- 1. To be considered acceptable for use, the instrument shall read+/- 0.005" from Examiner:
~/
the actual thickness measured.
Garreth
,./
- 2. Unless otherwise specified, numbers run in the direction of flow. Letters go Schroeder Si1m Name
'97',,(///
Level II Date: 8/9/2025 clockwise when facing downstream direction of flow (right hand rule).
Reviewer:
!Z~
Jeremy T. Timm Si1m Name Level III Date: 8/9/2025 I'
Form: UT-11R2
Flow-Accelerated Corrosion (FAC) Ultrasonic Thickness Report Exam Location around flange neck downstream of valve S821166 Location A
B C
1 0.709" 0.697" 0.665" 2
0.747" 0.705" 0.608" 3
0.781" 0.639" 0.618" 4
0.743" 0.660" 0.608" 5
0.770" 0.681" 0.592" 6
0.740" 0.652" 0.582" 7
0.750" 0.683" 0.611" 8
0.735" 0.660" 0.575" 9
0.689" 0.661" 0.580" 10 0.747" 0.653" 0.586" 11 0.702" 0.665" 0.659" 12 0.709" 0.676" 0.643" Page 2 of3 NDE Report # PSL-UTT-017 Readings taken at 12 spaced locations around flange neck starting location 1 offset from defect area at TDC using right hand rule with flow.
A,B,C locations at prepped areas on flange neck starting closest to flange face with A, B near center and C near weld toe.
.I------------,
a b C Defect area 11 2
10 3
4 6
7 Flow ---+
Side view View looking upstream Form: UT-I I R2
Flow-Accelerated Corrosion (FAC) Ultrasonic Thickness Report Exam Location at plugged defect area on flange neck downstream of valve SB21166 Location A
B C
0.590" 0.604" 0.606" Readings taken at prepped areas adjacent to plugged defect area View looking down Flange
.__ Pipe Page 3 of3 NDE Report # PSL-UTT-017 Form: UT-I I R2
St. Lucie Nuclear Plant, Unit 2 Docket No. 50-389 Fifth 10-Year lnservice Inspection Interval Relief Request (RR) #3 L-2025-147 Enclosure Proposed Alternative for Through-wall Flaw Acceptance in Weld Neck Flange Transition Zone ATTACHMENT 2 STRUCTURAL INTEGRITY ASSOCIATES, INC., CALCULATION 2552494.301 St. Lucie Flange Wall Thinning Evaluation (24 pages follow)
13 Structural Integrity Associates, Inc.
CALCULATION PACKAGE PROJECT NAME:
U2 PSL Finite Element Analysis and N-513 CLIENT:
PLANT:
File No.: 2552494.301 Project No.: 2552494 Quality Program Type: [8J Nuclear D Commercial NextEra Energy St. Lucie Nuclear Power Plant, Unit 2 CALCULATION TITLE:
St. Lucie Flange Wall Thinning Evaluation Document Affected Project Manager Preparer(s) &
Revision Pages Revision Description Approval Checker(s)
Signature & Date Sianatures & Date 0
1 - 22 Initial Issue A-1 -A-2 Y-=*d.
jf(H.,vt~
v - -~
Yanni Patten Younes Marih 8/13/25 8/13/25
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Jianxin Wang 8/13/25
Table of Contents 1.0 OBJECTIVE................................................................................................................ 4 2.0 METHODOLOGY........................................................................................................ 4 3.0 DESIGN INPUTS......... :.............................................................................................. 5 3.1 Geometry and Material.................................................................................... 5 3.2 Piping Loads.................................................................................................... 6 3.3 Bolt Preload..................................................................................................... 7 3.4 Wall Thickness Data........................................................................................ 8 3.5 Cement Lining................................................................................................. 8 4.0 ASSUMPTIONS.......................................................................................................... 8 5.0 FINITE ELEMENT MODEL......................................................................................... 8 5.1 Geometry and Element Selection.................................................................... 9 5 1. 1 Elastic-Perfectly Plastic Properties.................................................................. 9 5.2 Boundary Conditions....................................................................................... 9 5.3 Internal Design Pressure................................................................................. 9 5.4 Piping Moment Loads.................................................................................... 10 6.0 LIMIT LOAD COLLAPSE EVALUATIONS................................................................ 10 7.0 RES UL TS OF ANALYSIS......................................................................................... 10
8.0 CONCLUSION
S........................................................................................................ 11
9.0 REFERENCES
.......................................................................................................... 12 APPENDIX A COMPUTER FILES....................................................................................... A-1 File No.: 2552494.301 Revision: 0 tJ Structural Integrity Associates. Inc.*
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List of Tables Table 1: Piping Loads........................................................................................................................ 6 Table 2. Maximum Bending Stresses [5)............................................................................................ 6 Table 3: Model Piping Loads............................................................................................................. 7 Table 4. NDE Values Versus Modeled Values................................................................................... 8 Table 5: Final Model Piping Loads.................................................................................................. 10 Table 6: Results............................................................................................................................... 10 List of Figures Figure 1. Flange Details...................................................................................................................... 5 Figure 2: Location of Flaw on Drawing [1]....................................................................................... 13 Figure 3: Through - Wall Leak Location [2]...................................................................................... 14 Figure 4: Inspection Locations & Report [6]..................................................................................... 15 Figure 5: Inspection Locations & Report Continued [6].................................................................. 16 Figure 6: Final Flaw Profile.............................................................................................................. 17 Figure 7: Finite Element Model Geometry, Global View.................................................................. 18 Figure 8: Mechanical Boundary Conditions..................................................................................... 19 Figure 9: Applied Pressure Loads................................................................................................... 20 Figure 10: von Mises Stress Plot with As-Modeled Thinning, Service Level A/B at 200% of the applied Loads 21 Figure 11: von Mises Stress Plot with As-Found Thinning, Service Level C/D at 200% of the applied Loads 22 File No.: 2552494.301 Revision: 0
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1.0 OBJECTIVE A through-wall leak was discovered in the Unit 2 Circulation Water (CW) system at St. Lucie Nuclear Plant (PSL). The leak is located on the welding neck of a 36-inch flange, located on line 1-36-CW-16.
See Figure 2 for location of the identified leak on PSL provided drawing [1]. Figure 3 provides an image of the leak location and flange configuration [2]. The 36-inch flange is carbon steel, SA-106 Gr. B, with a cement lining, and is safety-related Class 3 piping [1].
Structural Integrity Associates, Inc. (SI) has been contracted to perform a detailed finite element analysis incorporating non-uniform wall thinning determined from the UT thickness data to justify continued operation utilizing ASME Code, Section Ill design by analysis criteria [3]. The objective of this calculation is to develop the finite element model, define the loads, and to perform limit analysis -
collapse load evaluations utilizing the ASME Code, Section Ill design by analysis rules [3].
The final of this calculation is to provide PSL with an allowable hole size based on ASME Code structural stability acceptance limits for continued operation.
2.0 METHODOLOGY The original Code of Construction is Section Ill, 1971 Edition with 1973 addendum [5].
To evaluate non-uniform wall thickness/local thinning, or "complex or combined stresses," detailed design qualification rules are taken from the ASME Code Design by Analysis approach (Section Ill, NB-3200 [3]). As a result, a detailed three-dimensional (3-D) finite element model (FEM) will be utilized in subsequent evaluations to calculate the stress field associated with localized thinning.
The primary stress design criteria for Service Level A (Normal) and Level B (Upset) conditions are based on the limit load design criteria of Subparagraph NB-3228.1, Limit Analysis [16]. NB-3228.1 states:
"The limits on General Membrane Stress Intensity (NB-3221. 1 ), Local Membrane Stress Intensity (NB-3221.2), and Primary Membrane Plus Primary Bending Stress Intensity (NB-3221.3) need not be satisfied at a specific location if it can be shown by limit analysis that the specified loadings do not exceed two-thirds of the lower bound collapse load The yield strength to be used in these calculations is 1. SSm. "
The allowable Stress, S, is used instead of the Class 1 Design Stress Intensity, Sm. As a result, the S value is substituted for the Sm, in regard to establishing the yield stress defined above. This is consistent with the design rules, as the yield stress defined here is the equivalent of the Local Primary Membrane Stress, which uses an allowable stress of 1.5Sm for Class 1 components, or 1.5S for Class 2/3 and 831.1 components.
Subparagraph NB-3213.28, Limit Analysis Collapse Load [16] states:
"The methods of limit analysis are used to compute the maximum load that a structure assumed to be made of ideally plastic material can carry. At this load, which is termed the collapse load, the deformations of the structure increase without bound "
Thus, a total load of 1 /(2/3) = 150% of the applied maximum loads on the degraded section of pipe must be sustained without any portion of the pipe plastically collapsing (i.e., the membrane stress across an entire section for a given location does not exceed the defined yield stress of 1.5S).
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The primary stress design criteria Service Level D (Faulted) conditions will be based on the limit load design criteria of Appendix F, F-1200(a), and will be based on the ASME Code, Section Ill, Appendix F, Subparagraph F-1341.3 [3]. F-1341.3 states:
"Static or equivalent static loads shall not exceed 90% of the limit analysis collapse load using a yield stress which is the lesser of 2.3Sm and 0. 7Su... "
Thus, a total load of 1 /0.9 = 111.1 % of the applied faulted loads on the degraded section of pipe must be sustained without any portion of the pipe plastically collapsing (i.e., the membrane stress across an entire section for a given location does not exceed the defined yield stress of 2.3S or 0.7Su).
For this purpose, a three-dimensional (3-D) finite element model (FEM) of the pipe-flange system is created and the appropriate maximum loading conditions (internal pressure and piping loads) are assessed. These loads will be conservatively increased up to 200% over the applied loads or until the structure plastically collapses (in terms of FEM this will be at the point of numeric instability). The total load, as a percentage of the applied load only the required 150% for service levels A&B and 111.1 % for service level D criteria identified above to determine if the degraded pipe would have remained structurally stable such that a violation of the required pressure boundary safety function would not have occurred.
The criteria for acceptability for service levels A&B is 150% of load applied. The criteria for acceptability for service levels Dis 111.1 % of load applied. The analysis will be set to run up to 200% for both cases to identify that there is additional margin on top of the acceptance criteria.
3.0 DESIGN INPUTS 3.1 Geometry and Material The following inputs for the flange with the leak are used in this analysis:
Code of Construction: Section Ill, 1971 Edition with 1973 addendum [4]
Flange outside diameter= 46 inches ( 0) [9]
Top of Hub outside diameter= 36 inches (A) [9]
Length of flange transition = 3.00 inches ( Y - tr) [9]
Nominal wall thickness of flange = 2.375 inches (tr) [9]
o ---
1--- R -I ET y
t Figure 1. Flange Details Flange material: Carbon Steel S/A-105 [5]
Straight pipe connecting to flange outside diameter= 36.0 inches [1]
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Nominal wall thickness of straight pipe connected to the flange= 0.375 inches [1]
Straight pipe material: Carbon Steel SA-106 Gr. B [5]
Maximum operating temperature= 95°F [1]
Design Pressure= 90 psig [1]
Youngs Modulus at design temperature, 125°F [1]:
o S/A-106 GR B: 29.14x106 psi [14, Table TM-1]
o S/A-105: 28.95 x106 psi [14, Table TM-1]. This value was used for the evaluation. Lower allowable stress is more conservative.
Allowable stress at design temperature, 125°F [1]:
o S/A-105: 20.0x103 psi [14, Table 1A].
o S/A-106 GR B: 17.1x103 psi [14, Table 1A]. This value was used for the evaluation.
Lower allowable stress is more conservative.
Ultimate tensile strength, Su:
o S/A-105: 70.0x103 psi [14, Table 1A].
o S/A-106 GR B: 60.0x103 psi [14, Table 1A]. This value was used for the evaluation.
Lower tensile stress is more conservative.
Thickness is confirmed by UT data [6].
Wear rate: 0.04 inches per year [2]
3.2 Piping Loads Piping moments and forces are provided from Reference [5], and are reproduced in Table 1:
Table 1: Piping Loads Loads Mx (ft-lb)
My (ft-lb)
Mz (ft-lb)
Fx(lb)
Fy (lb)
Fz (lb)
-3,359 2,650
-3,537
-939
-4,582
-406 Thermal
-3,577
-6,618
-7,333
-3,880
-4,537
-1,958 Per the stress report [5] and stress analysis model drawing [5], -Z direction in Table 1 is in the axial direction. The Y direction is vertical.
For the OBE and SSE load cases, reference [5] reports the bending stresses, reproduced in Table 2, below:
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Table 2. Maximum Bending Stresses [5]
OBE(psi) 1,535 DBE(psi) 962 Page 6 of 22 F0306-01R4 info@structint.com iZ 1-877-4SI-POWER e structinl.co m @)
These stresses were calculated for a circular pipe section with an outer diameter (OD) of 36 inches and an inner diameter (ID) of 35.25 inches. Based on this information, the bending moments responsible for these stresses can be determined using the following formula, per Subparagraph NB-3652 [3]:
where:
(Jb
- 21 M=--
D Ob = Bending stress (psi) as shown in Table 2.
D = Outer diameter of the circular pipe section (inches).
I
= Moment of inertia of the circular pipe section (in4).
M = bending moment (in-lbs).
Consequently, the bending moments applied to the model are calculated using the specified dimensions and the corresponding bending stresses described above. These moments are applied in the most critical orientation within the model. This orientation is determined by identifying the direction that produces the highest tensile stress in the region of interest, specifically the flaw region (see Figure 7).
All loads were transformed from the coordinate system in reference [5] to match the model's coordinate system. They are presented in Table 3, below:
Table 3: Model Piping Loads Loads Mx (ft-lb)
My (ft-lb}
Mz (ft-lb}
Fx(lb}
Fy (lb}
Fz (lb}
DW 3,537 2,650
-3,359 406
-4,582
-939 OBE
-47,3221 DBE
-29,6571 Thennal 7,333
-6,618
-3,577 1,958
-4,537
-3,880 Note 1: The flaw is located at Top Dead Center of the flange, and Mz is the direction of axial bending, which is the most conservative direction to apply the moment in.
3.3 Bolt Preload Per reference [12] the torque requirement for the flange bolting is 400 ft-lbs for 1.5-inch nominal diameter bolts.
Reference [13, page 79] defines an equation to calculate a nut factor based on preload testing.
Rearranging this equation allows for the determination of the achieved preload, based on the bolting torque. The rearranged equation and the resulting preload are as follows:
- Where, 12 X T 12 X ( 400)
Fp = D X K = (l.S) X O.l6 = 20,000 lbs Fp = Achieved preload (lb.)
T = Torque, 400 ft-lb (design torque load [12])
D = Nominal bolt diameter 1.5-inch K = Nut Factor, 0.16, [13]
Thus, the preload used in the evaluation at 100% of the torque is 20,000 lbs per bolt.
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3.4 Wall Thickness Data The wall thickness was taken from the examination report [6] and shown in Figure 4 and Figure 5.
The model was conservatively thinned 150 mils on all inner surfaces, leaving 0.6-inches at the thickest part of the flange neck and 0.225-inches at the weld of the flange to pipe, with a pipe thickness of 0.225-inches. In the final thinning map, the hole is conservatively extended to 5" (axially) by 14" (circumferentially) to reach the maximum allowable size that the flaw could be. Additionally, a 0.5-inch into the flange plate and 0.5 inch vertical into the flange plate was removed for any growth axially into the flange plate itself.
This approach is conservative since the lowest reported value (outside of the flaw area) are shown below, including two-times or more the wear rate of 0.04-inches per year provided [2]. Since the next refueling outage is in Spring 2026, this would satisfy any corrosion seen in the repetitive NOE data.
Table 4. NOE Values Versus Modeled Values NOE Grid Point [6]
NOE Minimum Reported Value {in) [6]
Modeled Value 1 {in)
A 0.689 0.600 B
0.639 0.450 C
0.575 0.300 Straight Piping Nominal 0.375 0.225 Note 1: The modeled values are conservativity under the minimum reported NOE values for each 360° circumferential band that was taken around the flange.
3.5 Cement Lining The cement lining of the flange is: 0.125-inches thick [11].
This lining is unreinforced and does not possess the strength in tension necessary to be considered a structural component. The cement lining is not modeled in the finite element model and not used in the stress calculation. This is considered conservative since the stiffness of the cement liner increases the stress in the steel component. The weight of the cement lining is included in the stress calculation deadweight load, per foot in the materials input section.
4.0 ASSUMPTIONS The following assumptions are used in this evaluation:
Poisson's ratio and density are assumed to be 0.3 and 0.28 lb/in3, respectively, for carbon steel.
These are typical values for carbon steel [10, Table PRO].
5.0 FINITE ELEMENT MODEL A three-dimensional (3-0) finite element model (FEM) of the flange and connecting pipe location is developed with the ANSYS finite element analysis software [8]. A FEM is developed to incorporate conservative value of wall thickness based off Figure 4 and Figure 5.
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To follow Code Case N-513-5 [15] general methodology with the addition of ASME Section Ill NB-3200
[16] a rectangular profile was chosen to model the allowable flaw size for both axially and circumferential directions. This also is a conservative approach, as it would produce increased stress intensity at the corners of the rectangle.
5.1 Geometry and Element Selection The FEM is constructed using AN SYS 8-node SOLID185 structural solid elements. Figure 7 shows a global view of the geometry used to develop the FEM. Note that an additional length of pipe is modeled on the end of the 36" pipe.
5 1. 1 Elastic-Perfectly Plastic Properties For the limit load collapse evaluation with Service Level C/D loads, elastic-perfectly plastic material properties are required with a yield stress that is the lesser of 230% of the Design Stress, S, or 70% of the ultimate strength, Su [3, Appendix F, F-1341.3]. The values for Sand Su are based on the design temperature of 125°F [1] and are equal to:
S = 17,100 psi [14]
Su= 60,000 psi [14]
Thus, the yield stress to be used in this limit analysis is 2.3S, or 39,330 psi for Service Level C/D.
Similarly, for Service Level A/B, the yield stress to be used in this limit analysis is 1.5S [3, NB-3225.2],
or 25,650 psi.
5.2 Boundary Conditions The free end of the modeled 36-inch flange's raised face is fixed in the axial and circumferential directions. The radial direction is left unconstrained to allow for expansion due to internal pressure. The free end of the pipe is left free in order to apply the bending moment and torque loads. The applied boundary conditions are shown in Figure 8.
5.3 Internal Design Pressure The Design Pressure, P, is 90 psig [1] and is applied to the interior surfaces of the model. In order to properly model the longitudinal stresses caused by pressure on the interior surface of the piping, and induced end-cap load is applied to the unconstrainted free end of the pipe, calculated as follows:
- where, TI' !D2 Fend-cap = P X A flow = p
- Fend-cap = End cap force on free end of flange (lb)
P
= Internal pressure (psi)
At1ow
= Wetted (flow) area (in)
ID
= Inside diameter of the flange (in)
The end-cap force is applied to the pilot node on free end surface of the pipe. The pilot node is described in Section 5.4. The internal pressure and end-cap pressures are shown in Figure 9.
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5.4 Piping Moment Loads The piping loads are applied by making use of a pilot node to transfer the loading. The TAR GE 170 target element type from the ANSYS element library is used to create the pilot node. The CONT A 175 contact element is used to create the contact surfaces that are aligned with the pilot node. The pilot node and surfaces are bonded together such that the loads applied to the pilot node are transferred to the respective surfaces on the flange.
The load combination for Service Level A/B is DW+OBE+ Thermal, and for Service Level D is DW+DBE+ Thermal. The maximum thermal load from the stress report is applied. The following piping loads in Table 5 are applied to the model.
Table 5: Final Model Piping Loads Mx (ft-lb)
My (ft-lb)
Mz (ft-lb)
Fx (lb)
Fy (lb)
Fz (lb)
Service Level A/B 10,870
-3,968
-54,258 2,364
-9, 119
-4,819 (DW+OBE+ THRM)
Service Level D 10,870
-3,968
-36,593 2,364
-9, 119
-4,819 lDW+DBE+ THRM) 6.0 LIMIT LOAD COLLAPSE EVALUATIONS Per Section 2.0, the static or equivalent static loads shall not exceed 2/3 (for Normal/Upset) or 90% (for Faulted) of the limit analysis collapse load. Thus, a total load of 1 /(2/3) = 150% (Normal/Upset) or 1 /0.9
= 111.1 % (Faulted) of the applied load must be sustained without plastic collapse. All loads (piping loads, end-cap pressure, and internal pressure) are applied simultaneously for the evaluation and a load factor of 1.6 (Normal/Upset) or 1.2 (Faulted) is applied for margin. The piping moment is conservatively applied in the worst direction, as determined in Section 5.4.
7.0 RESULTS OF ANALYSIS The model with as-found thinning successfully meets the criteria specified in Section 2.0 for both Normal/Upset and Faulted conditions. Table 6 tabulates the results for the evaluations).
Table 6: Results Percentage of Service Level A/B Load Percentage of Service Level D Applied <1>
Load Applied <2>
200%
200%
Notes:
- 1.
Using Service Level A/B loads, a passing score of greater than 150% is needed. The 200% applied load is arbitrary and is only intended to show margin.
- 2.
Using Service Level D loads, a passing score of greater than 111 % is needed. The 200% applied load is arbitrary and is only intended to show margin.
Von Mises stress plots are shown for the geometry profile in Figure 10 and Figure 11.
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8.0 CONCLUSION
S Based on the application of wall thickness data provided to SI [6] for the flange, the components meets the limit load design criteria outlined in Subparagraph NB-3228.1, Limit Analysis [16) with a conservatively extended hole size of 5-inches axially x 14-inches circumferentially with a 0.5-inch into and vertically on the flange plate.
The criteria for acceptability for service levels A&B is 150% of lo-ad applied. The criteria for acceptability for service levels Dis 111.1 % of load applied. The analysis was set to run up to 200% for both cases.
Both cases remained stable up to the cap of 200% which identifies that there is additional margin on top of the acceptance criteria while remaining stable.
In conclusion the allowable through-wall rectangular flaw in the axial direction is 5-inches and 14-inches circumferentially with a 0.5-inch into and vertically on the flange plate. The allowable flaw sizes are significantly larger than the characterized bounding flaw dimensions and therefore is acceptable for continued operation until the next scheduled outage pending NRC acceptance through a relief request.
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9.0
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
REFERENCES PSL Drawing 2998-G-125 sh. CW-F-2, Rev 29, "Large Bore Piping Isometric Circ. Water - Yard, SI File No. 2552494.205.
Email Chain from Hector Ramirez (PSL),
SUBJECT:
"2A ICW leak", Dated 8/8/2025, SI File No.
2552494.208.
ASME Boiler and Pressure Vessel Code, Section Ill, Rules for Construction of Nuclear Facility Components, 2017 Edition.
ASME Boiler and Pressure Vessel Code, Section Ill, Rules for Construction of Nuclear Facility Components, 1971 through Summer 1973 Edition.
Stress Calculation, CW-3000A Rev 17, "ST. LUCIE UNIT 2-Evaluation of ICW Discharge Piping", EC296540, Rev. 0, January 2024, SI File No. 2552494.201.
UT Data Report #PSL-UTT-017, "Flow-Accelerated Corrosion (FAC) Ultrasonic Thickness Report", August 2025, SI File No. 2552494.203.
Drawing No. 2998-G-171, Rev. 33, "Circ. Water", SI File No. 2552494.205 ANSYS Mechanical APDL (UP20170403), Release 18.1, SAS IP, Inc.
Tube-Turn Flange, F/angeDimensions-150/bF/anges, ASTM A181 Grade 1, B16.5., Catalog pages 102-103, SI File No. 2552494.206.
- 10. ASME Boiler and Pressure Vessel Code,Section II, Part D, 2019 Edition.
11. Email from H. Ramirez(PSL) to D. Denis (SIA), "RE: PSL U2 ICW Header Leak - SIA Discussion", August 11, 2025, SI File No. 2552494.208.
- 12. Attachment 5, Page 32, PSL Procedure O-GMM-99.17, Rev. 12, "Threaded fastners on Pressure Boundaries, Structural Steel and Plant Equipment", March 2023, SI File No.
2552494.206.
- 13. Good Bolting Practices, A Reference for Nuclear Power Plant Maintenance Personnel, Volume 1: Large Bolt Manual, EPRI, Palo Alto, CA: 1987, NP-5067-V1 SI File No. 2552494.210.
- 14. ASME Boiler and Pressure Vessel Code, Section II-Part D, Material Properties, 2017 Edition.
- 15. ASME Boiler and Pressure Vessel Code, Code Case N-513-5, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping and Gate ValvesSection XI, Division 1," April 18, 2018.
- 16. ASME Boiler and Pressure Vessel Code, Section Ill, Rules for Construction of Nuclear Facility Components, 2007 Edition.
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Figure 2: Location of Flaw on Drawing [1]
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Figure 3: Through - Wall Leak Location [2]
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Exam Location around flange neck downstream of valve S821166 Location A
B C
1 0.709" 0.697" 0.665" 2
0.747" 0.705" 0.608" 3
0.781" 0.639" 0.618' 4
0.743" 0.660" 0.608" 5
o.no" 0.681" 0.592" 6
0.740" 0.652" 0.582' 7
0.750" 0.683" 0.611' 8
0.735" 0.660" 0.575' 9
0.689" 0.661" 0.580" 10 0.747" 0.653" 0.586' 11 0.702" 0.665" 0.659' 12 0.709" 0.676' 0.643' Page 2 of3 NDE Report # PSL-UTI-017 Readings taken at *12 spoced locations around flange neck starting location *1 offset from defect area at TDC using right hand rule with flow.
A,B,C locations at prepped areas on flange neck starting closest to flange face with A, B near center and C near weld toe.
FI,ng,1 Weld
~
~ab<
'\\
~--,
Flow---
Sidt,-itn*
Defect area V~ t\\* looling upstrt.un Figure 4: Inspection Locations & Report [6]
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Page 3 of3 NDE Report # PSL-UlT-017 Exam Location at plugged defect area on flange neck downstream of valve SB21166 File No.: 2552494.301 Revision: 0 SJ Structural Integrity '
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Location A
B C
0.590" 0.604" 0.606' Readings taken at prepped areas adjacent to plugged defect area View looking down Flange Pipe Figure 5: Inspection Locations & Report Continued [6]
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weld to flange axla[,i, weld transition
- -~---- - -
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clrc~
-90 Oin 0.6 0.3 in 0.563 0.61n 0.525 0.9 in 0.488 l.2 in 0.45 l.S in OA13 1.Bln 0.375 2.l in 0.338 2.4 1n 0.3 2.7 in 0.263 31n 0.225 4in 0.225 Sin 0.225 Sin 0.225 7 in 0.225
-60
-48
-36 0.6 0.6 0.6 0.563 0.563 0.563 0.525 0.525 0.525 0.488 0.488 0.488 0.45 0.45 0.45 0.413 0.413 0.413 0.375 0.375 0.375 0.338 0.338 0.338 0.3 0.3 0.3 0.263 0.263 0.263 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225
-22
-11 11 22 36 0.6 0.563 0.525 0.488 0.45 OA13 0.375 0.338 0.3 0.263 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 Figure 6: Final Flaw Profile info@structint.com 1-877-4SI-POWER e 48 0.6 0.563 0.525 0.488 0.45 0.413 0.375 0.338 0.3 0.263 0.225 0.225 0.225 0.225
- 0. 5 60 90 0.6 0.6 0.563 0.563 0.525 0.525 0.488 0.488 0.45 0.45 0.413 0.413 0.375 0.375 0.338 0.338 0.3 0.3 0.263 0.263 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 0.225 Page 17 of 22 F0306-01R4 structint.com E@
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Flange As Modeled Hole Straight Pipe Figure 7: Finite Element Model Geometry, Global View ANSYS R18.1 Page 18 of 22 F0306-01R4 info@structint.com iZ 1-877-'ISI-POWER e slructint.com @)
l ELEMENTS MAT NOM U
6011 Preload F
M Piping Moment File No.: 2552494.301 Revision: 0
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Figure 8: Mechanical Boundary Conditions ANSYS R18.1 Piill NO.
1 Circumferential and Axial BC$
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f.UM:'.l<ES
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- ao Figure 9: Applied Pressure Loads ANSYS Press\\Jre (200%)
RlB.1 (Units are in terms of psi. For this example, the pressures shown are increased by 200% for Se/Vice Level A/8 (Normal/Upset) Case.)
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1 Maximum Stress Location 21:1.:;L..:
Figure 10: von Mises Stress Plot with As-Modeled Thinning, Seivice Level A/B at 200% of the applied Loads File No.: 2552494.301 Revision: 0
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Structural Integrity
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(Units are in terms of psi.)
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1 Figure 11: van Mises Stress Plot with As-Found Thinning, Service Level CID at 200% of the applied Loads File No.: 2552494.301 Revision: 0 e
Structural /n/egrlty Associates, Inc*
(Units are in terms of psi.)
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File No.: 2552494.301 Revision: 0 SJ Structural lntegrily :
Associales, Inc.*
APPENDIX A COMPUTER FILES Page A-1 of A-2 F0306-01R4 info@slructint.com m 1-877-'ISI-POWER e struclinl.com @)
File Name pipe-flange_AB.inp pipe-flange_CD.inp File No.: 2552494.301 Revision: 0
{J Structural Integrity I Associa/es, Inc.* :
Descriotion ANSYS input file to generate the finite element model and Service Level A/8 analvsis ANSYS input file to generate the finite element model and Service Level C/D analvsis Page A-2 of A-2 F0306-01R4 info@structint.com m l -877-4SI-POWER e structint.com ~