L-2020-025, Unit 2 ISI 4th Interval Relief Request 17, Proposed Alternative to Use ASME Code Case N-513-4
| ML20038A380 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 02/07/2020 |
| From: | Godes W Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2020-025 | |
| Download: ML20038A380 (36) | |
Text
- l=PL.
FEB Q 7 2020 L-2020-025 10 CFR 50.55a ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
St. Lucie Unit 2 Docket No. 50-389 Unit 2 ISi 4th Interval Relief Request 17 Proposed Alternative to Use ASME Code Case N-513-4 In accordance with the provisions of 10 CFR 50.55a(z)(2), Florida Power and Light (FPL) hereby requests Nuclear Regulatory Commission (NRC) approval of a proposed alternative to the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code), ~ection XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," for use at the~* Lucie Plant.
On February 3, 2020, a through-wall leak was identified on a 30-inch elbow downstream of the 2A intake cooling water (ICW) pump. Subsequently, it was determined that Code Case N-513-3, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping,Section XI, Division 1," could not be applied to piping elbows where the leak was located. As a result, the 2A ICW train was declared inoperable on February 3, 2020 at 2005 hours0.0232 days <br />0.557 hours <br />0.00332 weeks <br />7.629025e-4 months <br />.
To address this issue, FPL requests approval to use ASME Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping,Section XI, Division 1," with limits on leakage and temporary *acceptance of flaws in moderate energy ASME Code Class 3 piping in lieu of the ASME Code,Section XI, requirements in paragraph IWD-3120(b) and article IWD-3400. The proposed alternative is presented in Attachment 1. Attachment 2 provides a sketch of the leak location.
Attachment 3 provides the UT wall thickness mapping results at the leak location.
Attachment 4 provides the Engineering examination report. Attachment 5 provides the structural integrity evaluation.
FPL requests approval of the proposed alternative as soon as possible but no later than February 10, 2020.
Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
L-2020-025 Page 2 There are no regulatory commitments contained in this submittal. If there are any questions or if additional information is required, please contact Mr. Wyatt Gades, St.
Lucie Licensing Manager at (772) 467-7435.
Sincerely, Wyatt Gades St. Lucie Licensing Manager Attachments cc:
NRC Region II Administrator NRC Resident Inspector NRC Project Manager
L-2020-025 Attachment 1 Page 1 of 9 St. Lucie Unit 2 4th 10-year ISi Interval Relief Request 17 Request to Use ASME Code Case N-513-4 Proposed Alternative in Accordance with 10 CFR 50.55a(z)(2)
-Hardship Without a Compensating Increase in Quality and Safety-
- 1. ASME CODE COMPONENT(S) AFFECTED A leak was identified on a 30-inch elbow on Intake Cooling Water (ICW) system piping as follows:
System 21, 1-30"-CW-9 (Intake Cooling Water Pump 2A Discharge only)
- 2. APPLICABLE CODE EDITION AND ADDENDA The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Rules for lnservice Inspection of Nuclear Power Plant Components,Section XI, 2007 Edition with Addenda through 2008 as amended by 10CFR50.55a, is the Code of Record for the St. Lucie Unit 2 4th 10-year interval.
~ ,.
The ASME Boiler and Pressure Vessel Code, Rules for Construction of Nuclear Power Plant Components, Section Ill, Class 3, 1971 Edition with Addenda through Summer 1973, is the Code of Record for St. Lucie Unit 2.
- 3. APPLICABLE CODE REQUIREMENT For ASME Code Class 3 components, paragraph IWA-4000 of ASME Code,Section XI 2007 Edition states that the requirements of IWA-4000 may be used.
- 4. REASON FOR REQUEST On February 3, 2020, at 2005 hours0.0232 days <br />0.557 hours <br />0.00332 weeks <br />7.629025e-4 months <br />, the St. Lucie Unit 2 "A" train ICW system was declared inoperable, which resulted in entry into the Action statement for the Intake Cooling Water System Limiting Conditions for Operation (LCO) 3.7.4, ASME Code Case N-513-3, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping .Section XI, Division 1," 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. Code Case N-513-3, (Revision 3, January 26, 2009) is approved for generic use by licensees in Nuclear Regulatory Commission (NRC) Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 17 (ADAMS Accession No. ML13339A689), with the condition that the repair or replacement activity temporarily
L-2020-025 Attachment 1 Page 2 of 9 deferred under the provisions of this Code Case shall be performed during the next scheduled outage.
ASME Code Case N-513-3 does not address the evaluation of flaws in certain locations of moderate energy piping components, such as elbows, bent pipe, reducers, expanders.
and branch tees. ASME Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping,Section XI, Division 1,"
(Revision 4, May 7, 2014) contains several revisions to ASME Code Case N-513-3 including expanding the applicability of the code case beyond straight pipe to include elbows, bent pipe, reducers, expanders, and branch tees. ASME Code Case N-513-4 has not been approved by the NRC for generic use by licensees. Use of ASME Code Case N-513-4 is proposed to allow temporary acceptance of the aforementioned through-wall flaw, which is in a moderate energy Class 3 piping elbow without performing repair or replacement activities, and thereby avoid a plant shutdown. Use of this alternative evaluation method in lieu of immediate action for such a degraded condition would allow Florida Power and Light (FPL) to perform additional extent of condition examinations while allowing time for safe and orderly long-term repair actions.
Plant shutdown activities result in additional plant risk. Such a shutdown would be inappropriate when an affected ASME Code component in a degraded condition is demonstrated to retain adequate margin to fulfill the component's function. Accordingly, compliance with the current code requirements results in a hardship without a compensating increase in the level of quality and safety.
Acceptance of this Relief Request will make the 2A ICW header operable. This will remove the single-point vulnerability with only one of two ICW headers operable.
Potential degradation mechanism causing leakage:
The through-wall flaws occurred in an elbow just downstream of the 2A ICW Pump discharge butterfly valve. The pump discharges into a 30" elbow that directs the flow vertically down through the discharge valve, enters a 30" elbow that directs the flow to horizontally enter the 2A ICW header. Although forensics have not been performed, it is reasonable to assume that flow turbulence caused degradation of the internal pipe coatings leading to the degradation of the elbow wall and consequential leaks.
Pipe Parameters:
Nominal pipe wall thickness: 0.375 inches Operating Temperature: 95°F Design Temperature: 125°F Operating Pressure: 90 psig Design Pressure: 90 psig
L-2020-025 Attachment 1 Page 3 of 9 Material Specification: ASTM A-234, Grade WPB or WPBW
- 5. PROPOSED ALTERNATIVE AND BASIS FOR USE Proposed Alternative Application of the evaluation methods of ASME Code Case N-513-4 to a Class 3 component that meets the operational and configuration limitations of Code Case N-513-4, paragraphs 1(a), 1(b), 1(c), and 1(d) is proposed in lieu of the requirements in IWC-3120, IWC-3130, IWD-3120(b), and IWD-3400 of ASME Code Section XI, as they relate to the evaluation, repair, and replacement of ASME Code Class 3 moderate energy piping systems with flaws. An ASME Code,Section XI, compliant repair or replacement will be completed at the next scheduled refueling outage or prior to exceeding the allowable flaw size, whichever comes first.
For a leaking flaw, the allowable leakage rate will be determined by dividing the critical leakage rate by a safety factor of four. The critical leakage rate is determined as the highest leakage rate that can be tolerated and will be based on the allowable loss of inventory or the maximum leakage that can be tolerated relative to room flooding, among others.
During .the temporary acceptance period, leaking flaws will be monitored daily as required by paragraph 2(f) of Code Case N-513-4 to confirm the analysis conditions used in the evaluation remain valid. Significant change in the leakage rate is reason to question that the analysis conditions remain valid and would require re-inspection per paragraph 2(f) of the Code Case. Any re-inspection must be performed in accordance with paragraph 2(a) of the Code Case.
I The NRC issued Generic Letter, "Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2, and 3 Piping (Generic Letter 90-05)," to address the acceptability of limited degradation in moderate energy piping. The generic letter defines conditions that would be acceptable to utilize temporary non-code repairs with NRC approval. The ASME recognized that relatively small flaws could remain in service without risk to the structural integrity of a piping system and developed Code Case N-513. NRC approval of Code Case N-513 versions in Regulatory Guide 1.147 allows temporary acceptance of partial through-wall or through-wall leaks for an operating cycle provided all conditions of the code case and NRC conditions are met. The code case also requires the owner to demonstrate system operability considering effects of leakage.
The ASME recognized that the limitations in Code Case N-513-3 were preventing needed use in piping components such as elbows, bent pipe, reducers, expanders, and branch tees and external tubing or piping attached to heat exchangers. Code Case N-513-4 was approved by the ASME to expand it for use at these locations and to revise several other
L-2020-025 Attachment 1 Page 4 of 9 areas of the code case. The following list provides a high level overview of the Code Case N-513-4 changes:
- 1. Revised the maximum allowed time of use from no longer than 26 months to the next scheduled refueling outage.
- 2. Added applicability to piping elbows , bent pipe, reducers, expanders, and branch tees.
- 3. Expanded use to external tubing or piping attached to heat exchangers.
- 4. Revised to limit the use to liquid systems .
- 5. Revised to clarify treatment of service level load combinations.
- 6. Revised to address treatment of flaws in austenitic pipe flux welds.
- 7. Revised to require minimum wall thickness acceptance criteria to consider longitudinal stress in addition to hoop stress.
- 8. Daily walkdown requirement for through-wall leaks changed to provide additional flexibility.
- 9. Other editorial changes to improve clarity.
Effect of Leaks on ICW Train 2A Header Flow and Adjacent Areas There are two through-wall leaks located in a 30-inch elbow on the discharge of the 2A ICW Pump just downstream of valve 8821163, Isolation Valve for ICW Pump 2A, discharge outlet flange weld. The leaks cannot be isolated frpm the ICW headers while
' I on-line.
Currently there is no effect on 2A ICW Train flow since the combined leakage is estimated to be approximately 5 to 10 gallons per minute (gpm). The design basis ICW header flow is 14,500 gpm. The normal and accident ICW header flow rates are throttled by the Component Cooling Water (CCW) Heat Exchanger Outlet Temperature Control Valves (TCV) 14.4A and 14.48. These valves throttle ICW header flow to achieve and maintain the CCW outlet temperature at 100°F set-point. The current leak rate has a negligible effect on the 2A ICW Train flow.
The Extended Power Uprate (EPU) analysis confirmed that an ICW flow rate of 14, 140 gpm is sufficient to remove the required EPU LOCA heat loads. The EPU LOCA analysis also conservatively uses a maximum ICW inlet temperature of 95°F.
Increased leakage flow reduces the flow margin available to the cooling capability of ICW Train 2A to adequately cool the 2A CCW Heat Exchanger. However, the header flow would still be able to meet the design basis LOCA minimum flow requirements assuming total leakage up to 90 gpm (safety factor of four). A significant margin would still exist
L-2020-025 Attachment 1 Page 5 of 9 since the system design basis flow (14,500 gpm) is 360 gpm greater than the 14, 140 gpm required for sufficient heat removal to remove the required EPU LOCA heat loads.
If the flaw size exceeds the allowable flaw sizes or exceeds the leak allowance, the header will be declared inoperable.
The flaw sizes have not grown since first detected as the leaks have been plugged and no additional leakage has been detected.
The net effect of increased leakage other than impact on header flow margin would be seawater spraying on adjacent equipment and on the floor area below. The adjacent equipment consists of structural support steel, coated piping and concrete flooring.
Housekeeping plugs have been installed in both through-wall flaws to eliminate the spray from the leaks and potential damage to adjacent equipment.
With water spraying out of the two flaws, the safety related equipment that is wetted is the tube steel support in the same plane as the leak area, the coated ICW piping below the elbow and the concrete. With the holes plugged and no leakage occurring there is no concern for degradation of the safety related equipment in the area. Monitoring will detect both the recurrence of leakage and any degradation of the wetted equipment.
Potential for Flooding Based on the layout design of the Intake Structure, leakage up to the nominal flow of 360 gpm or more would not cause flooding. The leaked water would flow to the intake bay below.
Leakage Effect of ICW Train 28 There is no effect on ICW Train 28 since the 2A and 28 ICW Trains are indepentjent. The leakage from the 2A Train does not interface with the 28 ICW Train Equipment.
Flaw Characterization Nondestructive examination (NOE) was performed to characterize the flaw length and extent of the two flaws identified. The two flaws identified are referred to as the "East Through Wall" flaw which was measured to be 0.5-inch axially by 0.375-inch circumferentially and the "West Through Wall" flaw which was measured to be 0.75-inch axially by 0.75-inch circumferentially. Note that a full set of UT wall thickness measurements around to the "West Through Wall" flaw was not able to be obtained due to an interference with the existing pipe support.
The flaw characterization employed is consistent with the standards described in ASME Section XI, IWA-3300 and by way of straight beam and angled beam ultrasonic testing (UT) NOE examination methods. The two through wall flaws in the 30-inch diameter ICW pipe were characterized as a single flaw having a circumferential extent of 7 inches with
L-2020-025 Attachment 1 Page 6 of 9 a surrounding wall thickness of 0.300 inch and having an axial extent of 1.75 inches with a surrounding wall thickness of 0.194 inch.
Thickness measurements were taken on the pipe directly surrounding the leak. No additional pitting was observed. Code Case N-513-4 paragraph 2(a) requires the full pipe circumference at the flaw location to be inspected to characterize the length and depth of all flaws in the pipe section. Circumferential readings were taken around the pipe (Attachment 4). Due to interferences with the existing support, the data was taken on a plane approximately 5-inches below the flaw location on 76% of the pipe circumference.
While the information is useful in characterizing the state of the pipe and confirming that the as-found through-wall leaks and thinning are localized, it does not fully satisfy the code case requirement.
Structural Integrity The structural integrity of piping system components that are designed to ASME Code requirements must be maintained in conformance with the ASME Section XI code per 10CFR50.55a(g) . This through wall leak in the ICW piping is a degraded condition that would require repair prior to return to service in accordance with ASME Section XI requirements.
This piping meets the criteria for the Code Case N-513-4 because the maximum operating temperature is not above 200°F and the operating pressure does not exceed 275 psig.
The design pressure and temperature of this portion of the ICW system is 90 psig and 125°F, respectively.
A calculation was com.pleted to demonstrate the 30-inch diameter piping wiith the flaws identified meets the structural integrity requirements of ASME Code Case N-513-4 and ASME *section XI, Appendix C. These non-planar flaws are evaluated as two planar flaws in the axial and circumferential directions. The structural analysis was completed to conservatively envelope all the UT measured pipe wall thickness values. This structural evaluation bounds the effects of any other areas of erosion/corrosion within this 30-inch diameter piping . Based on this analysis, this 30-inch diameter ICW system piping is structurally sound with the identified flaws. This analysis takes into consideration both pressure and design basis bending stress on the piping and gives acceptable flaw size in both the circumferential and axial directions.
The maximum allowable flaw size is 1.75-inches in the axial direction and 10 inches in the circumferential direction to maintain structural integrity. Note that UT measurements were not able to be taken beyond the "West Through Wall" flaw due to accessibility constraints caused by the adjacent support.
The "West Through Wall" flaw could not be fully inspected due to interferences with the adjacent support, which reduces the accuracy of the characterization of the circumferential flaw. The "East Through Wall" flaw is characterized as extending
L-2020-025 Attachment 1 Page 7 of 9 approximately 1. 75-inches beyond the through-wall flaw location. Comparison of the "East" and "West" through wall flaw thickness measurements near the leak shows that in general, thinning is more extensive near the "East" leak. As the complete UT data could not be taken on the "West Through Wall" flaw (Attachment 3 & 4), it is assumed that this is a flaw that extends 1. 75" into this area. Therefore, it is reasonable to assume that for the "West Through Wall" flaw, the characterized flaw extends no more than 1. 75-inches into the obstructed area. The result would be a characterized through-wall flaw in the circumferential direction of approximately 8.75-inches. This is still less than the 10-inch allowable circumferential length. It can be reasonably concluded that the characterized circumferential through-wall flaw is bounded by the allowable through-wall flaw. Thus, the acceptance criteria of Code Case N-513-4 are met.
Other Actions ASME Code Case N-513-4 includes provisions for periodic NOE UT inspection of the flaw not to exceed thirty days since no flaw growth evaluation is being used in this case and daily walkdowns of the flaw to confirm the analysis conditions remain valid. This is being tracked with a corrective action .
Twice daily plant rounds will be used to meet the daily walkdowns of the flaw action. The maximum cumulative leakage is 90 gpm. The flaws have been plugged to stop the leakage and will remain plugged until the elbow repair is completed.
The guidance also includes augmented inspections of at least five similar susceptible locations to that of the flaw. A corrective action or similar mechanism will track completion of this activity.
\
FPL intends to repair or replace the elbow during the next scheduled refueling outage utilizing an ASME Code approved method .
Conclusion In summary, FPL will apply ASME Code Case N-513-4 to evaluate the through-wall leak identified in a Class 3 ICW piping elbow at the Saint Lucie Nuclear Power Plant, which is within the scope of the code case. Code Case N-513-4 utilizes technical evaluation approaches that are based on principles that are accepted in other ASME Code documents already acceptable to the NRC . The application of this code case, in concert with safety factors on leakage limits, will maintain acceptable structural and leakage integrity while minimizing plant risk and personnel exposure by minimizing the number of plant transients that could be incurred if degradation is required to be repaired based on ASME Code,Section XI acceptance criteria only.
L-2020-025 Attachment 1 Page 8 of 9
- 6. DURATION OF PROPOSED ALTERNATIVE The proposed alternative is requested for Unit 2 reaches mode 5 for the upcoming SL2-25 outage, currently scheduled for February 17, 2020.
- 7. PRECEDENT
- 1. Exelon Generation Company, LLC (Exelon) submitted a similar request to use ASME Code Case N-513-4 at Braidwood Station, Units 1 and 2; Byron Station, Unit Nos. 1 and 2; Calvert Cliffs Nuclear Pow~r Plant, Units 1 and 2; Clinton Power Station, Unit No. 1; Dresden Nuclear Power Station, Units 2 and 3; LaSalle County Station, Units 1 and 2; Limerick Generating Station, Units 1 and 2; Nine Mile Point Nuclear Station, Units 1 and 2; Oyster Creek Nuclear Generating Station; Peach Bottom Atomic Power Station Units 2 and 3; Quad Cities Nuclear Power Station Units 1 and 2; R. E. Ginna Nuclear Power Plant; and Three Mile Island Nuclear Station, Unit 1. Exelon requested use of the code case for the evaluation and temporary acceptance of flaws in moderate energy Class 2 and 3 piping in lieu of the same ASME Code requirements referenced herein. A September 16, 2016 NRC letter authorized use of ASME Code Case N-513-4 at each plant (ADAMS Accession Number ML16230A237).
- 2. Entergy Nuclear Operations, requested authorization of a proposed alternative to certain requirements of the ASME Code, Section X1, Article IWD-3000 for the Pilgrim Station. Specifically, it was proposed to use alternate analytical evaluation criteria for acceptance of through-wall flaws. The alternate analytical evaluation criteria were based on the draft Code Case N-513-4. The NRC granted verbal authorization of the proposed alternative on March 26, 2014. The safety evaluation associated with the authorization was ;provided via letter dated September 30, 20*14 (ADAMS Accession Number ML14240A603), '
- 3. FirstEnergy Nuclear Operating Company (FENOC) submitted a similar request to use ASME Code Case N-513-4 at the Perry Nuclear Power Plant. FENOC requested use of the code case for the evaluation and temporary acceptance of flaws in moderate energy Class 2 and 3 piping in lieu of the same ASME Code requirements referenced herein (ADAMS Accession Number ML 17232AOOO). The safety evaluation associated with the request was provided via letter dated October 16, 2017 (ADAMS Accession Number ML17270A030).
- 4. Entergy Nuclear Operations, requested to use an alternative flaw evaluation to that of ASME Code Case N-513-3 at Arkansas Nuclear One to disposition a pinhole leak at *,
the corner of an elbow in the service water piping in lieu of performing repair on the basis that complying with the ASME Code requirement to repair the flaw would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. The safety evaluation associated with the request was provided via letter dated March 16, 2015 (ADAMS Accession Number ML15070A428).
L-2020-025 Attachment 1 Page 9 of 9
- 5. Omaha Public Power District, submitted a relief requested for a proposed alternative, temporary acceptance of a pinhole leak in a raw water system piping elbow. It proposed to use an alternative methodology to ASME Code Case N-513-3 to disposition a pinhole leak in lieu of immediately performing a repair on a leaking elbow.
The safety evaluation associated with the request was provided via letter dated November 19, 2014 (ADAMS Accession Number ML142318310).
- 6. South Caroline Electric and Gas Company, submitted a request for alternative to implement Code Case N-513-4 at VC Summer Unit 1 due to a pinhole leak discovered in the Service Water System. It requested the use of Code Case. N-513-4 for the analysis of this branch tee connection to allow continued operation. The safety evaluation associated with this request was provided via letter dated April 10, 2019 (ADAMS Accession Number ML19101A293).
- 8. REFERENCE
- 1. Letter from D. T. Gudger of Exelon to the NRC Document Control Desk, "Proposed Alternative to Utilize Code Case N-513-4,'Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, Division 1',"
dated January 28, 2016 (Accession No. ML16029A003)
- 2. Letter from J. A. Dent, Jr. of Entergy to the Document Control Desk, "Pilgrim Relief Request PRR-25, Proposed Alternative, Request for Relief for Temporary Acceptance of a Flaw in Salt Service Water (SSW) System Pipe Spool JF29-8-4," dated March 5, 2014 (Accession No. ML14073A059)
L-2020-025 Attachment 2 Page 1 of 1 Leak Location
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Attachment 3 GIR 20-005 Pa e 1 of 5 fj Page 1 of 5
- General Engineering Examination Report GIR Number# 20-005 l=PL Plant Saint Lucie WO # 40703901-02 AR. # 02343401 Unit/Common/Other (Shop, etc.)
Unit 02 Subject I Component: Photo Attached: Outage: N/A 2A ICW Discharge Header Piping CW-9 YES Reference/ Procedure: Requestor: Request Date:
NOE 5.28 Rev. 1 Engineering 2/4/2020 Inspection Objective/ Criteria: AR 02343401 documents the identification of two through-wall leaks on 2A ICW Discharge Header Piping CW-9. Per the request of Engineering, NOE to take UT Thickness measurements surrounding the leaks to determine pipe wall thickness.
Results I Objective Evidence: This GIR documents the data acquisition of two through wall leaks (East through wall & West through wall). East through wall approximate dimensions 3/8" width x Yz" in height.
West through wall approximate dimensions % width x % in height. See attached data sheets. Data was not acquired in certain locations due to structural supports.
Comments I Attachments:
Through wall leak location Looking Southwest
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GIR 20-005 Pa e 5 of 5
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Cod Pearson 2/4/2020 Date
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Attachment 4 Page 1 of 3 GIR 20-007 Pa e 1 of 3 General Engineering Examination Report GIR Number# 20-007 l=PL Plant Saint Lucie WO # 40703901-02 AR # 02343401 Unit/Common/Other (Shop, etc.}
Unit 02 Subject/ Component: Photo Attached: Outage: N/A 2A ICW Discharge Header Piping CW-9 YES Reference I Procedure: Requestor: Request Date:
NOE 5.28 Rev. 1 Engineering 2/5/2020 Inspection Objective/ Criteria: AR 02343401 documents the identification of two through-wall leaks on 2A ICW Discharge Header Piping CW-9. Per the request of Engineering, NOE verify grid location relative to through wall leaks, verify areas data was not acquired, and measure leak locations tangent to elbow cheek.
- Results/ Objective Evidence: See pictures and sketch below.
Comments I Attachments:
Pa e 2 of 3 GIR 20-007 Pa e 2 of 3 22.5" AREA INACCESSIBLE I_
I Pa e 3 of 3 GIR 20-007 Pa e 3 of 3 2/5/2020 Date
~5/ /
'L(_~
Date
L-2020-025 Attachment 5 St. Lucie Code Case N-513-4 Structural Evaluation of Leaking ICW Elbow (Following 15 Pages
- 11
File No.: 2000146.301 Project No.: 2000146
'3 Structural Integrity Quality Program Type: J:gj Nuclear D Commercial Associates, Inc.
CALCULATION PACKAGE PROJECT NAME:
St. Lucie Code Case N-513-4 Evaluation of Leaking ICW Elbow CONTRACT NO.:
02407648 CLIENT: PLANT:
Florida Power & Light St. Lucie Nuclear Plant, Unit 2 CALCULATION TITLE:
Code Case N-513-4 Evaluation of Leaking Intake Cooling Water Elbow Project Manager Preparer(s) &
Document Affected Revision Description Approval Checker(s)
Revision Pages
... Sianature & Date Sianatures & Date 0 1 - 15 Draft Issue Preparer:
s~~~ S¥Jf~
Stephen Parker Stephen Parker i SMP 2/6/20 SMP 2/6/20 Che ker:
I
- (' ; C, #~~ .fa~
Eric ouston EJH 216120
Table of Contents 1.0 OBJECTIVE .... ...... ... ..... ....... ... ... ..... ..... ..... .. ... ... ....... ............. ......... .. .............. .... .. ... ..3 2.0 METHODOLOGY ....................... .. ........... .................................................................. 3 3.0 DESIGN INPUTS ..... ..... .. .......... ...... .......... ... ................... ..... .... .......... ....... ..... ............ 4 4.0 ASSUMPTIONS ....... .. ....... ................ .. .. ... .... ........................... .... .. ...... ... .... ............... 8 5.0 CALCULATIONS .............................................................................................. ......... 8 5.1 Applied Loads .................................................................... ........ ..... .. .... .. ... .. .. 8
- 5. 1. 1 Hoop Stress ...... ............ .............. .. ... .. ........ ... ........... .. ................ .... ... ... .... .. .... 8
- 5. 1.2 Axial Stresses ... .. .......... ... .... ... ...... ... ..... ..... .. .... .... ... ....... .. ..... .. .... ..... .. ............ 9 5.2 Stress Intensity Factor Calculations ......... ................... ............. .... .... .. ............ 9 5.3 Critical Fracture Toughness Determination .. .. .. .. ... ........ ................ ............... 11 6.0 RESULTS OF ANAL YSIS .. .. ..... ... .. ...... ... .......... ... ....... ... ........ ... ...... .... .......... .. ......... 11
7.0 CONCLUSION
S AND DISCUSSION ... .. ....................... .... ....... ........ .. ...................... 14
8.0 REFERENCES
.... ................. ..................................... .. ...... ...................................... 15 List of Tables Table 1: Moments at Thinning Location .................................................~: .. ............................ 8 Table 2: Load Combinations ...................................... ... ................ ..... .. ... ........ .. .......... .... ... . 11 Table 3: Allowable Axial Through-Wall Flaw .... ............ .. ................................ .................... . 13 Table 4: Allowable Circumferential Through-Wall Flaw................................... ..... .. .. .. ......... 13 Table 5: Pressure .Blowout Check .. .. ..... ...... ... ... ..... ........ .................................................... 14 List of Figures Figure 1. Detailed UT Measurement Pattern and Results ..... .................................... .... ........ 5 Figure 2. Location of Localized Thinning on 1-30-CW-9 Elbow .... .......................................... 6 Figure 3. Stress Report Nodal Isometric Drawing ... .. ..... ...................... ..................... .. ........ .. 7
1.0 OBJECTIVE A through -wall leak was discovered in an elbow of the Intake Cooling Water (ICW) system at St. Lucie Nuclear Plant (St. Lucie), Unit 2. The thinning is located on a 90-degree elbow on line 1-30-CW-9 downstream of valve l-SB21163. The 30-inch elbow is a cement lined carbon steel pipe and is safety related Class 3 piping. The objective of this calculation is to demonstrate suitability for continued operation in accordance with ASME Code Case N-513-4 [1] based on the latest examination data .
2.0 METHODOLOGY The flaw evaluation herein is based on the criteria prescribed in ASME Code Case N-513-4, which allows for the temporary acceptance of part-wall and through-wall flaws in moderate energy Class 2 or Class 3 piping. N-513-4 evaluation criteria includes rules for the evaluation of piping components such as elbows, branch tees and reducers. Flaws in these components may be evaluated as if in straight pipe provided the stresses used in the evaluation are adjusted to account for geometric differences. Details are provided in N-513-4 for determining these adjusted stresses.
For piping component such as elbows, N-513-4 provides guidance for evaluation of through-wall flaws. The Code Case allows non-planar, through-wall flaws to be characterized and evaluated as planar (i.e., crack-like), through-wall flaws in the axial and circumferential directions. Allowable through-wall flaw sizes in the axial and circumferential direction are calculated and are shown to bound the observed flaw. The measured wall thickness values in the pipe section containing the flaw are bounded by a thinner analyzed thickness (i.e. , the wall thickness surrounding the flaw is assumed to be uniformly thinned to the analyzed thickness, tadj). This conservatively ignores the load carrying capacity of the pipe wall that is greater than tadj*
Code Case N-513-4 evaluation criteria rely on the methods 'given in ASME Section XI, Appendix C [2].
Linear Elastic Fracture Mechanics (LEFM) criteria are conservatively employed as described in Article C-7000. Equations for through-wall stress intensity factor parameters Fm, Fb and Fare given in Appendix I of the Code Case. Allowable flaw lengths are determined iteratively through comparison of the calculated stress intensity factors to a critical fracture toughness defined in C-7200 of Section XI , Appendix C.
The NRC has not generically reviewed and approved N-513-4 in the current edition of Regulatory Guide 1.1 47 [3]. Florida Power & Light (FPL) will need to submit a relief request to the NRC to receive approval to use N-513-4 for the St. Lucie Unit 2, Class 3 moderate energy piping .
As stated above, Code Case N-513-4 evaluation criteria rely on the methods given in ASM E Section XI, Appendix C. Linear Elastic Fracture Mechanics (LEFM) criteria are conservatively employed as described in Article C-7000. Equations for through-wall stress intensity factor parameters Fm, Fb and Fare given in Appendix I of the Code Case, although the Code Case allows for alternate stress intensity factor parameters to be used. For circumferential through-wall flaws, the Code Case stress intensity factor parameters are valid over a range of mean pipe radius to thickness (Rm/t) ratios from 5 to 20 and become increasingly conservative for Rm/t>20. The Code Case states that alternative solutions for Fm and Fb may be used when R/t is greater than 20 [1 , Appendix 1-2]. Takahashi has proposed alternate stress intensity factor parameters, which are valid over the range of 1.5 to 80.5 [4]. Since the Rm/t ratios in the present analysis are greater than 20, the Takahashi parameters are appropriate to use. Therefore, for the circumferential through-wall analysis, the Takahashi stress intensity factor parameters are used in place of File No.: 2000146.301 Page 3of15 Revision: O F0306-01R3
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the Code Case stress intensity factor parameters . Axial through -wall flaws are evaluated using the stress intensity factor parameter from the Code Case, Appendix I. Allowable flaw lengths are determined through iteration comparing calculated stress intensity factors to a critical fracture toughness defined in C-7200 of Section XI, Appendix C.
3.0 DESIGN INPUTS The following design inputs are used in the evaluation:
- 1. Nominal Pipe Size = 30-inch Elbow [5]
- 2. Outside diameter (near location of leak) = 30.0 inches [5]
- 3. Nominal wall thickness = 0.375-inch [5]
- 4. Elbow bend radius = 30 inches (short radius [5] for 30-inch elbow)
- 5. Maximum normal operating temperature = 95°F [5]
- 6. Maximum normal operating pressure = 90 psig [5]
- 7. Code of Construction: ASME Section 1111971 Edition through the Summer 1973 Addenda [6, 7]
- 8. Elbow Material: A-234 Grade WPB [8]
- 9. Young's modulus= 27,900 ksi [6, Table 1-6.0]
The NDE inspection results [9] provide the thickness data characterizing the wall thickness around the circumference of the pipe. Measurements in Reference [9] are taken around the majority of the elbow circumference in a plane approximately five inches below the areas of localized thinning. The plane of thinning as well as a 22.5 inch section of the elbow circumference was not inspected due to a lack of accessibility [10] . An additional set of detailed UT measurement around the localized thinning is also provided to define the thinning profile [11] .
Figure 1 displays a composite image of the two sets of detailed UT measurements and the spacing of the grid, where each point displayed represents a point measurement that was taken. The "East Through Wall" lea,k, as defined in the NDE report, is characterized as having an extent of 0.5-inch axially by 0.375-inch circumferentially. Within the same plane, the "West Through Wall" leak, as defined in the NDE report, is characterized as having an extent of 0.75-inch axially by 0.75-inch circumferentially. Additional measurements were taken in a 45-degree pattern I around each through-wall leak at a distance of 0.25-inch I away from the adjacent measurement. Due to accessibility issues, a full set of UT wall thickness measurements adjacent to the "West Through Wall" leak was not able to be obtained.
File No.: 2000146.301 Page 4of15 Revision: 0 F0306-01R3 l>
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Figure 1 also displays the characterized axial and circumferential extents of the thinning with regard to the two surrounding wall thickness, tadj, used in this evaluation . The tadi used for the allowable axial flaw size evaluation is 0.194-inch . The tadi used for the allowable circumferential flaw size evaluation is 0.300-inch.
The tadi is a conservative characterization based on the wall thickness measurements taken around the circumference of the pipe [9]. The average measured wall thickness of the NOE data provided in Reference [9] is equal to 0.450-inch. The size of the evaluated through-wall flaw is characterized to encompass measured thicknesses below tadi and is determined to be 1. 75 inches axially by 7 inches circumferentially. Note that the characterization of 7 inches circumferentially is limited by the accessibility issues previously identified adjacent to the "West Through Wall" leak. It is likely that additional thinning exists within the uninspectable region that would increase the characterized circumferential flaw length. A comparison to the allowable circumferential flaw length will be performed to quantify the available margin between the characterized and allowable circumferential flaw sizes. This approach is not in strict compliance with paragraph 2(a) of the Code Case, which requires that the full pipe circumference at the flaw location be inspected to characterize the length of depth of all flaws in the pipe section, and must be included in the request for NRC relief.
The circumferential location of thinning around the elbow, ¢ [1, Figure 7] is taken as negative 45 (-45) degrees for the "East Through Wall" leak"based on the images provided by FPL (see Figure 2), which places the thinning past the elbow cheek and into the elbow intrados. The "West Through Wall" leak was measured as 5 inches away from the "East Through Wall" leak towards the extrados. This measurement converts to approximately 19 degrees, which results in the circumferential location angle of negative 26
(-26) degrees for the "West Through Wall" leak.
Figure 2. Location of Localized Thinning on 1-30-CW-9*Elbow File No.: 2000146.301 Page 6of15 Revision: 0 F0306-01R3 l>
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Determination of the fracture toughness, J1c, used in the evaluation is based on Section XI , Appendix C, C-8320 [2], which specifies that "reasonable lower bound fracture toughness data" may be used to determine the allowable stress intensity factor, Kie. Beginning with the 2013 Edition,Section XI, Appendix C contains additional guidance for the temperature for the onset of upper-shelf behavior [12, Table C-8321-2]. Note that the NRC has approved the 2013 Edition of Section XI, Appendix C without exception [13]. Based on the guidance in [12, Table C-8321-2], upper shelf material toughness is expected at temperatures greater than 23.2°F (interpolated upper shelf temperature for tadj of 0.300-inch used in the axial flaw evaluation). The temperature for the expected onset of upper shelf material toughness for the circumferential flaw evaluation is bounded by that of the axial flaw. Therefore, J1c is taken from ISi Code of Record and used in the evaluation as 350 in-lb/in 2 for the circumferential direction [2 , Table C-8321-1] and 300 in-lb/in 2 for the axial direction [2, Table C8322-1].
Design moment loading relative to the Code of Construction requirements is taken from the design stress
. report [7]. Based on the design stress report and the orientation of the piping relative to the global coordinate system (see Figure 3), it has been determined that the applicable bending moments to the cross section of the piping exist in the X and Z direction. The reported moment in the Y direction is, therefore, torsion as it is parallel to the run of the pipe at Node 7010. Torsional loads to not generate through-wall bending stresses, which is the required load to be considered as defined in Section 3.3 of Code Case N-513-4 [1] . Therefore, only the moments in the X and Z direction are used in the evaluation for resultant primary bending moment, as reported in Table 1.
Nodal location I of thinning \
Figure 3. Stress Report Nodal Isometric Drawing File No.: 2000146.301 Page 7of15 Revision: 0 F0306-01R3 l>
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Table 1: Moments at Thinning Location Component Moments (ft-lbs) MsRss MsRss Load MX MZ (ft-lbs) (in-lbs)
DW -112 2400 2,403 28,831 OBE 2574 6280 6,787 81,444 DBE 4076 8778 9,678 116,138 TH -2055 -4613 5,050 60,600 4.0 ASSUMPTIONS
- 1. Poisson's ratio is assumed to be 0.3, which is a typical value for carbon steel.
- 2. A corrosion allowance is not considered in the evaluation. The ongoing inspection requirements in Code Case N-513-4 address the possibility of flaw growth during the temporary acceptance period.
5.0 CALCULATIONS The applied stresses and resulting stress intensity factors are calculated using an evaluated wall thickness, tadj, of 0.194-inch for the allowable axial flaw size and 0.300-inch for the allowable circumferential flaw size.
5.1 Applied Loads Axial and circumferential (i.e., hoop) stresses used in this evaluation are calculated from the evaluated wall thicknesses (tadj}, the nodal stresses in Table 1, and the maximum operating pressure. The evaluated wall thicknesses are used to determine the section properties in the flaw evaluations. The nominal wall thickness, tnom, is used to calculate the flexibility characteristic 'h' in the flaw evaluation, consistent with the guidance of N-5 13-4.
5 1. 1 Hoop Stress For the allowable axial flaw length in an elbow, the hoop stress, ah, may be determined from Equation 9 of N-513-4:
(1)
(2) where:
p = maximum operating pressure, psig Do = outside diameter, in File No.: 2000146.301 Page 8of15 Revision: O F0306-01 R3 e
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= evaluated wall thickness =tadj, in Rbend = elbow bend radius, in Ra = outside radius, in
¢ = location of circumferential angle of thinning, rad h = flexibility characteristic [6, Figure NC-3672.9(a)-1]
Mb = resultant moment loading at the applicable Service Level, in-lb I = moment of inertia, in 4 tnom = nominal wall thickness, in Rm = mean radius based on nominal thickness, in Use of Equation 1 is specific to the fracture mechanics methodology provided in Code Case N-513-4 to determine structural integrity of the component with localized thinning. It is not to be used for design purposes in determining the minimum required wall thickness of the component. The hoop stress for each Service Level is given below in Table 3.
- 5. 1.2 Axial Stresses For the allowable circumferential flaw length, the axial stress due to pressure, deadweight and seismic loading is presented below. For axial membrane stress due to pressure, Om, Equation 10 of N-513-4 is:
(3)
B1 is the primary stress index for pressure loading. As allowed by the Code Case, the primary stress indices B1 and 82 are taken from a more recent edition of the ASME Code [14, Figure ND-3673.2(b)-1]. For elbows, B1 is 0.5.
For axial bending stress, Ob, due to deadweight and seismic moments, Equation 11 of N-513-4 is:
(4)
The coefficient B2for elbows is [14, Figure ND-3673.2(b)-1]:
B 2
=_!_]_
2/ (5) hl3 5.2 Stress Intensity Factor Calculations For LEFM analysis, the stress intensity factor, K1, for an axial flaw is taken from Article C-7000 [2] as prescribed by N-513-4 and is given below:
(6)
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(7) where:
SFm =structural factor for membrane stress (see [2, C-2620])
F =through-wall stress intensity factor parameter for an axial flaw under hoop stress (given in Appendix I of N-513-4) ah = hoop stress, ksi a =flaw depth (taken as half flaw length for through-wall flaw per Appendix I of N-513-4), in Q =flaw shape parameter (unity per Appendix I of N-513-4)
K1r = K1 from residual stresses at flaw location (assumed negligible as the flaw location is in the base metal)
Only the hoop stress influences the allowable axial flaw length, which is a function of pressure and axial moment loading.
For LEFM analysis, the stress intensity factor, K1, for a circumferential flaw is taken from Article C-7000 [2]
as prescribed by N-513-4 and is given below:
KI = Kim +Kib +KI,. (8)
K1rn = SF,11F,11(J"111 J;;i (9)
Kib = [SF,pb+ (J"e]FbJ;;i (10) where:
Fm = through-wall stress intensity factor parameter for a circumferential flaw under membrane stress (given in [4])
am = membrane stress, ksi SFb =structural factor for bending stress (see [2, C-2620])
ab = bending stress, ksi ae =thermal stress, ksi Fb =through-wall stress intensity factor parameter for a circumferential flaw under bending stress (given in [4])
K1r = K1 from residual stresses at flaw location (assumed negligible as the flaw location is in the base metal)
Note that the through-wall flaw stress intensity factor parameters are a function of flaw length.
The residual stress term, K1r, is taken as zero as the thinning is remote from a weld. Table 2 shows the specific load combinations considered herein for the allowable circumferential flaw calculations.
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Table 2: Load Combinations Load Combination Service Level P+DW A P+DW+OBE B P+DW+DBE c 5.3 Critical Fracture Toughness Determination For LEFM analysis, the static fracture toughness for crack initiation under plane strain conditions, Kie, is taken from Article C-7000 [2] as prescribed by N-513-4 and is given below:
(11)
E'=___§_2 (12) 1-u where:
J1e = material toughness, in-lb/in 2 E =Young's modulus, ksi v = Poisson's ratio Based on the design input listed above, Kie = 95.9 ksi-in°* 5 for axial flaws and Kie = 103.6 ksi-in°* 5 for circumferential flaws. The allowable flaw lengths are determined iteratively by increasing flaw length until the stress intensity factor is equal to the static fracture toughness.
6.0 RESULTS OF ANALYSIS Based on inputs in Section 3.0 and using equations from Section 5.0, the allowable through-wall flaw lengths in the axial and circumferential direction are calculated for each Service Level. Fo'r a surrounding wall thickness of 0.194-inch , the allowable through-wall flaw in the axial direction is 1. 75 inches as shown in Table 3 for Service Level B. Based on the inspection data given in References [11], the analyzed thickness and axial flaw length bound the observed thinning. Thus, the acceptance criteria of Code Case N-513-4 are met for the axial flaw.
For a surrounding wall thickness of 0.300-inch , the allowable through-wall flaw in the circumferential direction is approximately 1O inches as shown in Table 4 for Service Level B. As discussed above, accurate characterization of the circumferential flaw is not possible based on the obstructions. The margin between the characterized and allowable circumferential flaw is approximately 3 inches. The "East" through-wall flaw is characterized as extending approximately 1. 75 inches beyond the through-wall leak location. Comparison of the "East" and "West" thickness measurements near the leak shows that in general, thinning is more extensive near the "East" leak. Therefore, it is reasonable to assume that for the "West" leak, the characterized flaw extends no more than 1.75 inches into the obstructed area . The result would be a characterized through-wall flaw in the circumferential direction of approximately 8. 75 inches.
This is still less than the 10-inch *allowable circumferential length. It can reasonably be concluded that the characterized circumferential through-wall flaw is bounded by the allowable through-wall flaw. Thus, the File No.: 2000146.301 Page 11 of 15 Revision: O F0306-01R3 e
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acceptance criteria of Code Case N-513-4 are met. As discussed above, relief from paragraph 2(a) of the Code Case is required to permit continued operation.
Code Case N-513-4, Paragraph 3.2( c) requires that the remaining ligament average thickness over the degraded area be sufficient to resist pressure blowout [1 , Equation 8]. Table 5 shows the required average thickness, tc,avg, as a function of the equivalent diameter of the circular hole, dadj, for which the wall thickness is less than tadi* Based on the inspection data given in References [11], the values in Table 5 bound the observed thinning. The values in Table 5 also bound the evaluated allowable through-wall flaw sizes in the axial and circumferential direction as the evaluated wall thicknesses, tadj, are greater than the required average thickness, tc,avg, for each flaw length. Thus, the Code Case requirement is met.
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~J Table 3: Allowable Axial Through-Wall Flaw Service Moment Hoop Stress Allowable Kim Kie SFm Level [in-lbs] [psi] Flaw Size [in] [ksi-in°*5] [ksi-in°*5]
A 2.7 28,831 11,890 2.87 95.67 95.9 B 2.4 110,276 20,446 1.75 95.90 95.9 c 1.8 144,969 24,090 2.00 95.16 95.9 Table 4: Allowable Circumferential Through-Wall Flaw Applied Applied Membrane Thermal Bending Allowable Service Primary Thermal K1 Kie SFb SFm Stress Stress Stress Flaw Size Level Moment Moment
[psi] [psi] [ksi-in°*5] [ksi-in°* 5]
[psi] [in]
nn-lbsl nn-lbsl A 2.3 2.7 28,831 60,600 2,250 1,920 1,320 15.60 103.32 103.6 B 2.0 2.4 110,276 60,600 2,250 1,920 5,048 9.99 103.57 103.6 c 1.6 1.8 144,969 60,600 2,250 1,920 6,636 10.50 103.19 103.6
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Table 5: Pressure Blowout Check d adj [in] tc,avg [in]
0.50 0.01 1.00 0.03 1.50 0.04 2.00 0.05 2.50 0.07 3.00 0.08 3.50 0.10 4.00 0.11 4.50 0.12 5.00 0.14 5.50 0.15 6.00 0.16 6.50 0.18 7.00 0.19 7.50 0.21 8.00 0.22 8.50 0.23 9.00 0.25 9.50 0.26 10.00 0.27 Code Case N-513-4, Paragraph 2(a) requires that the full pipe circumference at the location of the flaw be inspected. The NOE data in Reference [9] includes 76 percent of pipe circumference on a plane approximately five inches below the flaw locations. While the information is useful in characterizing the state of the piping and confirming that the as-found through-wall leaks and thinning are localized, it does not satisfy the Code Case requirement.
7.0 CONCLUSION
S AND DISCUSSION A through-wall leak in the 30-inch elbow on line 1-30-CW-9 downstream of valve l-SB21163 of the ICW system at St. Lucie Unit 2. Allowable through-wall flaw lengths have been calculated in accordance with ASME Code Case N-513-4.
The allowable through-wall flaw in the axial direction is 1.75 inches. The allowable through-wall flaw in the circumferential direction is 10 inches. The allowable through-wall flaw lengths are based on an evaluated wall thickness of 0. *194-inch for the axial flaw and 0.300-inch for the circumferential flaw. Table 5 shows the requirements to meet the Code Case pressure blowout limits.
The NRC has not generically reviewed and approved N-513-4 in the current edition of Regulatory Guide 1.147 [3]. FPL will need to submit a relief request to the NRC to receive approval to use N-513-4 for the St. Lucie Unit 2, Class 3 moderate energy piping.
The observed thinning is boanded by the results of the analysis; thus, the structural evaluation criteria of Code Case N-513-4 are met. However, the inspection requirements of Code Case N-513-4, Paragraph File No.: 2000146.301 Page 14of15 Revision: 0 F0306-01R3
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2(a) were not met due to lack of accessibility on the pipe in the plane of thinning. Additional actions are required by FPL through examination of the affected piping or a request for relief from this requirement of the Code Case.
The Code Case requires additional actions by the owner, such as:
- Volumetric reinspection (30-day inteNal): Paragraph 2(e)
- Augmented volumetric examinations: Paragraph 5
8.0 REFERENCES
- 1. ASME Boiler and Pressure Vessel Code, Code Case N-513-4, "Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping Section XI, Division 1," May 7, 2014.
- 2. ASME Boiler and Pressure Vessel Code,Section XI, Appendix C, 2007 Edition with 2008 Addenda.
- 3. Regulatory Guide 1.147, "lnservice Inspection Code Case Acceptability, ASME Section XI, Division 1," Revision 18, U.S. Nuclear Regulatory Commission, March 2017.
- 4. Y. Takahashi , "Evaluation of Leak-Before-Break Assessment Methodology for Pipes With a Circumferential Through-Wall Crack. Part I: Stress Intensity Factor and Limit Load Solutions,"
International Journal of Pressure Vessels and Piping, 79, 2002, pp. 385-392, SI File No.
0801508.204.
Water-Yard," SI File No. 2000146.205.
- 6. ASME Boiler and Pressure Vessel Code, Section Ill, 1971 Edition through the Summer 1973 Addenda.
- 7. FPL Calculation No. CW-3000A, Revision 14, "St. Lucie Unit 2- Evaluation of ICW Piping," SI File No. 2000146.201.
February 4, 2020, SI File No. 2000146.208.
- 9. FPL General Engineering Examination R~port, GIR 20-006 , "2A ICW Discharge Header l?iping CW-9," February 5, 2020, SI File No. 2000146.203.
- 10. FPL General Engineering Examination Report, GIR 20-007, "2A ICW Discharge Header Piping CW-9," February 5, 2020, SI File No. 2000146.203.
- 11. FPL General Engineering Examination Report, GIR 20-005, "2A ICW Discharge Header Piping CW-9," February 4, 2020, SI File No. 2000146.203.
- 12. ASME Boiler and Pressure Vessel Code,Section XI, Appendix C, 2013 Edition.
- 13. Codes and standards, 10CFR 50.55a (September 9, 2019).
- 14. ASME Boiler and Pressure Vessel Code, Section Ill, 2013 Edition.
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