L-2018-174, Structural Integrity Associates Engineering Report No. 0901350.401, Revision 4, Leak-Before-Break Evaluation - Accumulator, Pressurizer Surge, and Residual Heat Removal Lines
| ML18299A119 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point |
| Issue date: | 10/12/2018 |
| From: | Fong M Structural Integrity Associates |
| To: | Florida Power & Light Co, Office of Nuclear Reactor Regulation |
| References | |
| 2000230248, L-2018-174 0901350.401, Rev 4 | |
| Download: ML18299A119 (85) | |
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Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 FPL Response to NRC RAI No. 4.7.4-3 L-2018-174 Attachment 19 Enclosure 2 Page 1 of 85 Structural Integrity Associates Engineering Report No. 0901350.401, Revision 4, "Leak-Before-Break Evaluation - Accumulator, Pressurizer Surge, and Residual Heat Removal Lines, Turkey Point Units 3 and 4,"
October 12, 2018
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Leak-Before-Break Evaluation L-2018-174 Attachment 19 Enclosure 2 Page 2 of 85 Report No.: 0901350.401 Revision No.: 4 Project No.: 1700109 File No.: 0901350.401.
October 2018 Accumulator, Pressurizer Surge and Residual Heat Removal Lines Turkey Point Units 3 and 4 Prepared by:
Reviewed by:
Approved by:
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Prepared for:
Florida Power & Light Company Purchase Order No. 2000230248 Prepared by:
Structural Integrity Associates, Inc.
San Jose, California
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Minji Fong
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Do Jun Shim
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David A. Gerber iii Report No. 0901350.401, Rev. 4 Date:
10/12/2018 Date:
10/12/2018 Date:
10/12/2018 SJ Structural Integrity Associates, Inc.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-17 4 Attachment 19 Enclosure 2 Page 3 of 85 REVISION CONTROL SHEET Document Number:
0901350.401
Title:
Leak-Before-Break Evaluation, Accumulator, Pressurizer Surge and Residual Heat Removal Lines, Turkey Point Units 3 and 4 Client: Florida Power & Light Company SI Project Number:
1700109 Section Pages Revision Date Comments Summary 0
4/15/2010 INITIAL ISSUE 111-X 1.0 1 1-7 2.0 2-1-2-2 3.0 3 3-3 4.0 4 4-15 5.0 5 5-18 6.0 6 6-13 7.0 7 7-2 8.0 8 8-5 3.0 3-2 1
5/6/2010 Clients' Comments Addressed 4.0 4-1, 4-6 5.0 5-5, 5-6, 5 5-19 6.0 6-4 8.0 8-4 Summary 2
7/10/2017 Updated 60-year results in V, Vlll-X 1.0 1-1 response to CAR 17-012.
6.0 6 6-14 Extended evaluation to cover 80 7.0 7 7-2 years of operation and to use 8.0 8 8-5 updated fatigue crack growth law.
Summary V
3 9/18/2017 Addressed client editorial 1.0 1-1, 1-3 comments 2.0 2-1 3.0 3-1, 3-2, 3-3 4-2-4-5, 4.0 4-9, 4-10 5.0 5-l 6.0 6-2, 6-5, 6-8 10, 6-13 7.0 7-1 IV SJ Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Summary 5.0 6.0 7.0 8.0 IX 5-3-5-23 6 6-4, 6 6-12, 6 6-16, 7-1-7-2 8-1, 8 8-4 Report No. 0901350.401, Rev 4
V
.4 L-2018-174 Attachment 19 Enclosure 2 Page 4 of 85 10/12/2018 Added maximum stress versus critical flaw size plots.
Updated through-wall crack growth calculation.
Updated references to remove proprietary source.
-13 Structural Integrity Associates, Inc.
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251
SUMMARY
L-2018-174 Attachment 19 Enclosure 2 Page 5 of 85 This report presents a leak-before-break (LBB) evaluation for the following lines at Turkey Point Nuclear Plant (PTN) Units 3 and 4 operated by Florida Power & Light Company (FPL). These lines are attached to the reactor coolant loop (RCL) and span from the connection to the RCL to the first isolation valve or the pressurizer as applicable:
- 1. 1 O" diameter Accumulator Lines - 3 lines ( one per RCL connected to cold leg)
- 2. 12" pressurizer Surge Line - 1 line attached to "B" loop
- 3. 14" residual heat removal line-1 line attached to "C" loop in Unit 3 and "A" loop in Unit 4( connected to hot leg)
The evaluation was performed to eliminate consideration of the dynamic effects of the postulated large pipe rupture for these lines. The LBB evaluation was performed in accordance with the 10 CFR 50, Appendix A GDC-4 and NUREG-1061, Vol. 3 [ 6] as supplemented by NUREG-0800, Standard Review Plan 3.6.3 [7].
The methodology used in determining LBB capabilities of the above lines at PTN Units 3 and 4 consisted of several steps. First, the relationship between the critical through-wall flaw length and the applied stress ( or moments) was determined on a generic basis for circumferential flaws.
The critical flaw size as used herein refers to the through-wall flaw length that becomes unstable under a given set of applied loads. Critical flaw sizes were calculated using the net limit load (net section plastic collapse) approach with conservative material properties. NUREG-1061 [6]
requires that the load combination considered in determining the through-wall flaw length include the normal operating loads (NOP), which consists of internal pressure, dead weight, and thermal expansion loads, plus the safe shutdown earthquake (SSE). Once the NOP+SSE load for a given location is known, the critical flaw length can be determined from the generic relationship. The "leakage flaw size" was determined as the minimum of one half the critical flaw size with a factor of unity on normal operating plus SSE loads. Thus, the leakage flaw size Vl SJ Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-174 Attachment 19 Enclosure 2 Page 6 of 85 as referred herein maintains a safety factor of 2 on the critical flaw size under normal plus SSE loads.
Leakage rates were determined as a function of stress ( or moment) on a generic basis for a given through-wall flaw length. NUREG-1061, Vol. 3 [6] requires that the NOP loads be used to determine the leakage. On a generic basis, a family of curves was developed relating the leakage with the NOP loads to the through-wall flaw length.
Given the relationships between the leakage flaw size versus NOP+SSE moments and leakage flaw size versus NOP moments above (for a particular leak rate), a relationship was developed between the NOP+SSE moments and the NOP moments that would result in a particular leak rate. This results in the bounding analysis curve (BAC). The actual piping NOP+SSE and NOP loads were then used to determine if the combination of those loads would meet that leakage (fall below the BAC). This particular scheme is very convenient for determining whether or not a particular leakage will be met for a piping system with many nodal points and associated moments, such as the auxiliary RCL piping lines considered in this evaluation.
A fatigue crack growth analysis was also performed to determine the growth of postulated semi-elliptical, inside surface flaws with an initial size based on ASME Code,Section XI [26]
acceptance standards. This showed that crack growth due to cyclic loadings was not significant such that it could be managed by the Section XI inspection program. In addition, a fatigue crack growth analysis was performed to show that a through-wall crack would not grow significantly, hereby, insuring that the leakage size flaw will not grow to the critical crack size.
The following summary of the LBB evaluation is formatted along the lines of the "Recommendations for Application of the LBB Approach" in the NUREG-1061 Vol. 3 [6]
executive summary:
(a)
The three piping systems considered in this evaluation are constructed of A 3 7 6 Type 316 stainless steel piping. At the operating temperature of these piping lines of 550°F to 653°F, this material is very ductile and it is not susceptible to cleavage-type fracture. In Vil SJ Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-174 Attachment 19 Enclosure 2 Page 7 of 85 addition, these systems have been shown not to be susceptible to the effects of corrosion, high cycle fatigue or water hammer.
(b)
Loadings have been determined from the original piping analysis, and are based upon pressure, dead weight, thermal expansion, and safe shutdown earthquake. All stress locations in these piping systems from the connection to the RCL to the first isolation valve or pressurizer, as applicable, were considered.
( c)
Minimum ASME Code material properties were used to establish conservative lower bound stress-strain properties to be used in the evaluations. For the fracture toughness properties, lower-bound generic industry material properties for the piping and welds have been conservatively used in the evaluations.
( d)
Crack growth analysis was conducted at the most critical locations on the evaluated piping, considering the cyclic stresses predicted to occur over the life of the plant. For a hypothetical flaw with aspect ratio of 10: 1 and an inltial flaw depth of 12.5% of pipe wall, the final flaw size after considering all plant transients for both 60 years and 80 years of operation is less than ASME Code Section XI allowable flaw size of 75%.
Hence, fatigue crack growth is well within the allowable flaw size for the auxiliary RCL piping.
( e)
The LBB evaluation is performed for leakage rates of 2 GPM (gallons per minute), 5 GPM and 10 GPM. All piping locations considered in the evaluation exhibit a minimum leakage rate of 10 GPM based on the normal operating and normal plus dynamic loads. NUREG-1061 Vol. 3 recommends that the leakage detection system be capable of measuring leakage rates 1/10 of the minimum leakage rate. The plant leak detection capability for both Units 3 and 4 is 1 GPM [8], thereby satisfying the leakage rate requirement.
(f)
Each of the piping systems considered in this evaluation is less than 51.2 feet in length and is not geometrically complex.
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Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-174 Attachment 19 Enclosure 2 Page 8 of 85 (g)
Crack growth of a leakage size crack due to a conservative seismic event was insignificant and the final crack size was smaller than the critical crack size.
(h)
For all locations, the critical size circumferential crack was determined for the combination of absolute values of normal operating plus SSE loads. The leakage size flaw was chosen such that its length was no greater than the critical crack size reduced by a factor of two for conservatism. Axial cracks were not considered as they are known to exhibit much higher leakage and more margin than circumferentially oriented cracks.
(i)
Another LBB acceptance criterion is, for all locations, determine the critical crack size for the combination of 1.4 times the normal plus SSE loads and select the leakage crack no greater than this critical crack size. Based on previous experience, this criterion is always bounded by the criterion of (h) above. Hence, in this evaluation, only the evolution based on criterion of (h) is performed.
G-n)
No special testing was conducted to determine material properties for :fracture mechanics evaluation. Instead, ASME Code minimum properties were utilized in the evaluations.
The material properties so determined have been shown to be applicable near the upper range of normal plant operation and exhibit ductile behavior at these temperatures.
(o)
Limit load analysis as outlined in NUREG-0800, SRP 3.6.3, was utilized in this evaluation in order to determine the critical flaw sizes since the materials involved in this evaluation are stainless steel piping.
Thus, the three piping systems evaluated in this report for PTN Units 3 and 4 qualify for the application ofleak-before-break analysis to demonstrate that it is very unlikely that the piping could experience a large pipe break prior to leakage detection. Results of the evaluation show that for all applicable pipe stresses, leak-before-break can be justified for a plant leak detection system of 1 GPM.
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Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 Section Table of Contents L-2018-174 Attachment 19 Enclosure 2 Page 9 of 85
1.0 INTRODUCTION
........................................................................................................... 1-1 1.1 Background...................................................................................................................... 1-1 1.2 Leak-Before-Break Methodology.................................................................................... 1-2 1.3 Leak Detection Requirement........................................................................................... 1-4 2.0 CRITERIA FOR APPLICATION OF LEAK-BEFORE-BREAK.................................. 2-1 2.1 Criteria for Through-Wall Flaws..................................................................................... 2-1 2.2 Criteria for Part-Through-Wall Flaws............................................................................. 2-2 2.3 Consideration of Other Mechanisms............................................................................... 2-2 3.0 CONSIDERATION OF WATER HAMMER, CORROSION AND FATIGUE............ 3-1 3.1 Water Hammer................................................................................................................. 3-1 3.2 Corrosion.......................................................................................................................... 3-2 3.3 High Cycle Fatigue.......................................................................................................... 3-3 4.0 PIPING MATERIALS AND STRESSES....................................................................... 4-1 4.1 Piping System Description, Operating Conditions and Geometry.................................. 4-1 4.1.1 Accumulator Lines................................................................................................... 4-1 4.1.2 Pressurizer Surge Line............................................................................................. 4-1 4.1.3 RHR Line.................................................................................................................. 4-2 4.2 Material Properties........................................................................................................... 4-2 4.2.1 Calculation ofZ Factors for Fracture Mechanics Analysis.................................... 4-3 4.2.2 Determination of Ramberg-Osgood Material Parameters...................................... 4-3 4.3 Applicable Stresses.......................................................................................................... 4-4 5.0 LEAK-BEFORE-BREAK EVALUATION.................................................................... 5-1 5.1 Evaluation of Critical Flaw Sizes.................................................................................... 5-1 5.2 Leak Rate Determination................................................................................................. 5-3 5.3 Bounding Analysis Curves.............................................................................................. 5-4 5.4 LBB Evaluation Results and Discussions........................................................................ 5-6 6.0 EVALUATION OF FA TIGUE CRACK GROWTH OF SURF ACE FLAWS.............. 6-1 6.1 Plant Transients................................................................................................................ 6-1 6.2 Stresses for Crack Growth Evaluation............................................................................. 6-1 6.3 Allowable Flaw Size........................................................................................................ 6-3 6.4 Fatigue Crack Growth Analysis....................................................................................... 6-4 6.4.1 Fatigue Crack Growth Law Used for 60-Year Operation Calculations.................. 6-4 6.4.2 Fatigue Crack Growth Law Used for 80-Year Operation Calculations.................. 6-5 6.4.3 Part Through-Wall Crack Growth........................................................................... 6-6 6.4.4 Through-Wall Crack Growth................................................................................... 6-6 6.4.5 Summary of Fatigue Crack Growth Analysis.......................................................... 6-8
7.0 CONCLUSION
S.............................................................................................................. 7-1
8.0 REFERENCES
................................................................................................................ 8-1 X
S} Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-174 Attachment 19 Enclosure 2 Page 10 of 85 Table 4-1.
Table 4-2.
Table 4-3.
Table 4-4.
Table 4-5.
Table 4-6.
Table 4-7.
Table 4-8.
Table 4-9.
Table 4-10.
Table 6-1.
Table 6-2.
Table 6-3 Table 6-4.
Table 6-5.
Table 6-6.
Table 6-7.
Table 6-8.
Table 6-9.
Table 6-10.
Table 6-11.
List of Tables Normal Operating Conditions for Leakage Evaluation.......................................... 4-6 Operating Conditions for Critical Flaw Size Evaluation........................................ 4-6 Pipe Geometry Inputs for Leakage Evaluation...................................................... 4-6 Pipe Geometry Inputs for Critical Flaw Size Evaluation....................................... 4-7 ASME Code Strength at Normal Operating Temperatures for Leakage Calculation
................................................................................................................................. 4-7 ASME Code Strength at Normal Operating Temperatures for Critical Flaw Size Calculation............................................................................................................. 4-8 Ramberg-Osgood Parameters for Leakage Calculation......................................... 4-8 Load Points for Accumulator Lines....................................................................... 4-9 Load Points for RHR Lines.................................................................................. 4-11 Loads for Units 3 and 4 Pressurizer Surge Lines................................................. 4-11 Accumulator Line_ Operating Condition TransientsC1).......................................... 6-10 RHR Line Operating Condition Transients [31].................................................. 6-11 Surge Line Operating Condition Transients [50]................................................. 6-12 Piping Loads for Accumulator and RHR Lines................................................... 6-13 Accumulator Line Maximum and Minimum Transient Stresses......................... 6-13 RHR Line Maximum and Minimum Transient Stresses...................................... 6-13 Stress Range for Accumulator Line..................................................................... 6-14 Stress Range for RHR Line.................................................................................. 6-14 Stress Range for Surge Line................................................................................. 6-15 Results of Fatigue Crack Growth Analysis for Part Through-Wall Flaws.......... 6-15 Results of Fatigue Crack Growth Analysis for Through-Wall Flaws.................. 6-16 XI Report No. 0901350.401, Rev. 4 I;
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Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 List of Figures L-2018-174 Attachment 19 Enclosure 2 Page 11 of85 Figure 1-1.
Representation of Postulated Cracks in Pipes for Fracture Mechanics Leak-Before-Break Analysis....................................................................................................... 1-5 Figure 1-2.
Conceptual Illustration oflSI (UT)/Leak Detection Approach to Protection Against Pipe Rupture........................................................................................................... 1-6 Figure 1-3.
Leak-Before-Break Approach Based on Fracture Mechanics Analysis with In-service Inspection and Leak Detection................................................................... 1-7 Figure 4-1.
Schematic of Piping Model and Selected Node Points for Accumulator Lines (Loops A, Band C), PTN Unit 3 [34, 35, 36]...................................................... 4-12 Figure 4-2.
Schematic of Piping Model and Selected Node Points for Accumulator Lines (Loops A, Band C), PTN Unit 4 [39, 40, 41]...................................................... 4-13 Figure 4-3.
Schematic of Piping Model and Selected Node Points for Pressurizer Surge Line, PTN Unit 3 [38).................................................................................................... 4-14 Figure 4-4.
Schematic of Piping Model and Selected Node Points for Pressurizer Surge Line, PTN Unit 4 [43).................................................................................................... 4-14 Figure 4-5.
Schematic of Piping Model and Selected Node Points for RHR Line, PTN Unit 3
[37]....................................................................................................................... 4-15 Figure 4-6.
Schematic of Piping Model and Selected Node Points for RHR Line, PTN Unit 4
[42]....................................................................................................................... 4-15 Figure 5-1.
Maximum Stress versus Critical Flaw Size for Accumulator Lines...................... 5-7 Figure 5-2. Maximum Stress versus Critical Flaw Size for RHR Lines................................... 5-7 Figure 5-3. Maximum Stress versus Critical Flaw Size for Pressurizer Surge Line (Nozzle Side at Pressurizer End)................................................................................................. 5-8 Figure 5-4. Maximum Stress versus Critical Flaw Size for Pressurizer Surge Line (Nozzle Side at Hot Leg End)...................................................................................................... 5-8 Figure 5-5.
Maximum Stress versus Critical Flaw Size for Pressurizer Surge Line (Pipe Side at Pressurizer End)..................................................................................................... 5-9 Figure 5-6.
Maximum Stress versus Critical Flaw Size for Pressurizer Surge Line (Pipe Side at Hot Leg End).......................................................................................................... 5-9 Figure 5-7.
Maximum Stress versus Critical Flaw Size for Pipe/Elbow (Z Factor= 1.0) of Accumulator Lines............................................................................................... 5-10 Figure 5-8.
- Leakage Flaw Size versus Normal Operating Stress of Accumulator Lines....... 5-11 Figure 5-9.
Leakage Flaw Size versus Normal Operating Stress of Pressurizer Surge Lines (Pipe Side at Pressurizer End).............................................................................. 5-12 Figure 5-10. Leakage Flaw Size versus Normal Operating Stress of Pressurizer Surge Lines (Nozzle Side at Pressurizer End).......................................................................... 5-13 Figure 5-11. Leakage Flaw Size versus Normal Operating Stress of Pressurizer Surge Line (Nozzle Side at Hot Leg End).............................................................................. 5-14 Figure 5-12. Leakage.Flaw Size versus Normal Operating Stress of Pressurizer Surge Line at Hot Leg End......................................................................................................... 5-15 Figure 5-13. Leakage Flaw Size versus Normal Operating Stress ofRHR Line at Hot Leg End 5-16 Xll
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Structural Integrity Associates, Inc.
Report No. 0901350.401, Rev. 4
Turkey Point Units 3 and 4 Docket Nos. 50-250 and 50-251 L-2018-174 Attachment 19 Enclosure 2 Page 12 of 85 Figure 5-14. BA Cs and Load Points for Accumulator Lines.................................................... 5-17 Figure 5-15. BA Cs and Load Points for RHR Lines................................................................ 5-18 Figure 5-16. BACs and Load Point for Pressurizer Surge Lines (Nozzle Side at Pressurizer End)