ML061240078
| ML061240078 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 05/01/2005 |
| From: | Alvarez A, Bamford W, Roarty D, Strauch P, Swamy S, David Tang Westinghouse |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| AEP:NRC:6055-03, TAC MC7287 WCAP-16428-NP, Rev 1 | |
| Download: ML061240078 (51) | |
Text
{{#Wiki_filter:Attachment 3 to AEP:NRC:6055-03 WESTINGHOUSE REPORT WCAP-16428-NP, REVISION 1, D. C. COOK UNIT 1 PRESSURIZER SAFETY VALVE NOZZLE SAFE-END WELD OVERLAY REPAIR
Westinghouse Non-Proprietary Class 3 WCAP-16428-NP May 2005 Revision 1 D.C.Cook Unit 1 Pressurizer Safety Valve Nozzle Safe-End Weld Overlay Repair OWestinghouse
WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-16428-NP Revision 1 D. C. Cook Unit 1 Pressurizer Safety Valve Nozzle Safe-End WVeld Overlay Repair D. Roarty D. Tang A. H. Alvarez W. H. Bamford May 2005 Veifier. ° P. L. Strauch Piping Analysis and Frcture Mechanics Approved: /,- (,,, S.A.Sw yMana Piping Analysis and Fracture Mechanics Westighouse Electric Company LLC P.O. Box 355 Pittsburgh, PA 15230-0355 0 2005 Westinghouse Electric Company LLC All Rights Reserved
iii TABLE OF CONTENTS I INTRODUCTION ....................................................... 1-1 2 BACKGROUND ....................................................... 2-1 3 WELD OVERLAY DESIGN METHODOLOGY ....................................................... 3-1 3.1 DESIGN CRITERIA ....................................................... 3-1 3.2 NOZZLE SAFE-END WELD OVERLAY DESIGN ...................................................... 3-1 4 MATERIAL PROPERTIES ....................................................... 4-1 4.1 MATERIALS ............... ; 4-1 4.2 WELD OVERLAY MATERIAL PROPERTIES ....................................................... 4-1 5 WELD OVERLAY FINITE ELEMENT ANALYSIS ......................................... 5-1 5.1 OBJECTIVE OF THE ANALYSIS ....................................................... 5-1 5.2 MODEL ....................................................... 5-1 5.3 WELD REPAIR SIMULATION AND DESIGN LOAD ANALYSIS ............................ 5-1 6 CRACK GROWTH ANALYSIS ........................................................ 6-1
6.1 INTRODUCTION
....................................................... 6-1 6.2 ALLOWABLE FLAW SIZE DETERMINATION ....................................................... 6-1 6.3 PRESSURIZER SAFETY NOZZLE TRANSIENTS AND PIPING LOADS ................ 6-2 6.4 STRESS CORROSION CRACK GROWTH..................................................................6-3 6.5 FATIGUE CRACK GROWTH ....................................................... 6-4 6.6 STRESS REPORT RECONCILIATION ....................................................... 6-9 7 WELD OVERLAYACCEPTANCE INSPECTION .................................... 7-1 8
SUMMARY
..................................... 8-1 9 REFERENCES ..................................... 9-1 WCAP-16428-NP Revision 1 May 2005
iv LIST OF TABLES Table 4-la Material Properties for Stainless Steel ............................................................... 4-2 Table 4-lb Stress-Strain Values for Stainless Steel ............................................................... 4-2 Table 4-2a Material Properties for SA 216 Grade WCC............................................................... 4-3 Table 4-2b Stress-Strain Values for SA 216 Grade WCC ............................................................... 4-3 Table 4-3a Material Properties for Alloy 690, 600 ............................................................... 4-4 Table 4-3b Stress-Strain Values for Alloy 690, 600 ............................................................... 4-4 Table 6-1 Summary of Transients ............................................................... 6-2 Table 6-2 Pressurizer Safety Nozzle Loads (X - North, Y - Vertical Up, Z - East) [13] ......................... 6-3 Table 6-3 Fatigue Crack Growth Results for Safety Nozzle Safe-End Inconel Weld Location, Axial Flaw ............................................................... 6-8 Table 6-4 Fatigue Crack Growth Results for Safety Nozzle Safe-End Stainless Steel Weld Location, Axial Flaw ............................................................... 6-8 Table 6-5 Fatigue Crack Growth Results for Safety Nozzle Safe-End Inconel Weld Location, Circumferential Flaw ............................................................... 6-9 Table 6-6 Fatigue Crack Growth Results for Safety Nozzle Safe-End Stainless Steel Weld Location, Circumferential Flaw ............................................................... 6-9 Table 6-7 Safety Nozzle Axial and Radial Displacements Due to Weld Overlay Repair ..................... 6-10 May 2005 Revision 1I WCAP-16428-NP Revision May 2005
v LIST OF FIGURES Figure 2-1 Westinghouse Pressurizer Configuration ........................................................... 2-3 Figure 2-2 Pressurizer Safety Nozzle Geometry for the Cast Head Configuration ........................... 24 Figure 3-1 Westinghouse Pressurizer Safety Nozzle Weld Overlay Design ...................................... 3-3 Figure 5-1 Axisymmetric Finite Element Model Used for Safety Nozzle Weld Overlay Analysis .5-3 Figure 5-2 Model of Weld Overlay Segments for the Safety Nozzle Weld Overlay Stress Analysis..........................................................................................54 Figure 5-3 Limiting Sections of Safety Nozzle Weld Overlay (Stress Path for Figure 5-4 through 5-7) ............................................................ 5-5 Figure 54 Axial Through-Wall Residual Stress Distribution at Alloy 82/182 Weld Location ......... 5-6 Figure 5-5 Hoop Through-Wall Residual Stress Distribution at Alloy 82/182 Weld Location ......... 5-6 Figure 5-6 Axial Through-Wall Residual Stress Distribution at Stainless Steel Weld Location ....... 5-7 Figure 5-7 Hoop Through-Wall Residual Stress Distribution at Stainless Steel Weld Location ....... 5-7 Figure 5-8 Axial Residual Stress Contour Plot at Ambient Conditions ............................................. 5-8 Figure 5-9 Hoop Residual Stress Contour Plot at Ambient Conditions ............................................. 5-8 Figure 5-10 Axial Residual Stress Contour Plot at Operational Conditions ....................................... 5-9 Figure 5-11 Hoop Residual Stress Contour Plot at Operational Conditions ....................................... 5-9 Figure 6-1 Fatigue Crack Growth Model Development for Water Environment .............................. 6-5 Figure 6-2 Reference Crack Growth Rate Curves for Stainless Steel in Air Environments .............. 6-7 May 2005 Revision 1I WCAP-16428-NP Revision May 2005
1-1 1 INTRODUCTION During the refueling outage in April 2005, an axially oriented indication was detected in the pressurizer safety valve nozzle to safe-end dissimilar metal weld at Donald C. Cook Unit 1. The nozzle is integrally cast into the pressurizer head, which is cast carbon steel SA216WCC. The nozzle was buttered with Alloy 82/182 filler metal and welded with Alloy 82/182 filler metal to a forged stainless steel safe-end. The function of the safe-end is to connect the pressurizer nozzle to the stainless steel pipe which leads to safety valve inlet During subsequent ultrasonic testing (UT) examinations, the indication was found to initiate at the inside surface of the nozzle, extending approximately 1.23" into the Alloy 82/182 weld and spanning 0.4" along the axis of the nozzle. The total wall-thickness at the weld location is 1.405". The indication was confined in the Alloy 82/182 weld material, there was no evidence that the indication extended into the adjacent stainless steel or carbon steel. A full structural weld overlay repair was performed to maintain weld integrity. Weld overlay is a repair and/or mitigation technique used to reinforce nozzle safe end regions and pipes susceptible to PWSCC (primary water stress corrosion cracking). ASME Code Case N-504-2 [3], "Alternate Rules for Repairs of Classes 1, 2, and 3 Austenitic Stainless Steel Piping" was used as guidance for the weld overlay design, which permits the use of weld deposit to build up the pipe thickness to the established acceptability requirements of Section XI, IWB-3640. The weld repair involves applying a specified thickness of weld material over the region in a configuration that assures that the structural integrity will be maintained. The weld material, Alloy 52, is applied by the GTAW (Gas Tungsten Arc Welding) process, and is considered highly resistant to IGSCC, TGSCC, (intergranular and transgranular stress corrosion cracking, respectively) and PWSCC. This process also minimizes the thickness and installation time of the weld overlay. The reinforcement material forms a structural barrier to stress corrosion cracking and produces a favorable residual stress condition that mitigates future crack initiation and/or propagation. This report will describe the geometry created for the weld overlay repair for the pressurizer safety valve nozzle safe-end, and provide the technical basis for its application. A finite element analysis was performed to determine the residual stresses resulting from the overlay repair, and these results were used to evaluate the acceptability of the repair, as will be discussed in detail in this report. Note that there are several locations in this report where proprietary information has been identified and bracketed. For each of the bracketed locations, the reason for the proprietary classification is given, using a standardized system. The proprietary brackets are labeled with three different letters, to provide this information, and the explanation for each letter is given below:
- a. The information reveals the distinguishing aspects of a process or component, structure, tool, method, etc., and the prevention of its use by Westinghouse's competitors, without license from Westinghouse, gives Westinghouse a competitive economic advantage.
- c. The information, if used by a competitor, would reduce the competitor's expenditure of resources or improve the competitor's advantage in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product.
- e. The information reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.
Introduction May 2005 WCAP-16428-NP Revision 1
2-1 2 BACKGROUND The Westinghouse Series 84 Pressurizer is designed for use in the primary loop of a closed cycle, pressurized light water nuclear power plant. Its function is to maintain the required reactor coolant system (RCS) pressure during steady state operation, limit the pressure changes caused by RCS thermal expansion and contraction during normal power plant load transients, and prevent the pressure in the RCS from exceeding the design pressure. The 1800 cubic foot units have three safety nozzles and one relief nozzle located in the upper head (Figure 2-1). Self actuating safety valves are designed to accommodate large volume insurges that are beyond the pressure limiting capability of the spray system and to prevent primary plant pressure from exceeding the design pressure by more than ten percent. A power-operated relief valve is set to open at slightly below design pressure, to minimize use of the safety valves. During the spring 2005 outage at D. C. Cook Unit 1, actions were initiated to characterize the weld contours of the safety and relief nozzles, and informational UT exams were carried out. The welds were inspected to meet industry recommendations given in EPRI Material Reliability Program Letter MRP-2004-05 [23]. It was one of these exams that identified the indication of interest, which was axial, and extends over the majority of the Alloy 82/182 weld region. The depth of the flaw was found to be 1.23 inches, or 87.5 percent of the wall thickness. Because of the depth of the flaw, and the potential for future propagation, a weld overlay repair was applied. The degradation mechanism is concluded to be PWSCC since the UT results indicate the flaw was oriented axially, multifaceted, and confined to the nickel alloy weld metal. This is consistent with recent industry findings. In September of 2003, cracking and leakage were discovered on pressurizer safety and relief nozzles in Unit 2 of Tsuruga Power Plant. Samples removed for destructive examinations contained the entire weld and a portion of the base metal on each side of the weld. Radiography was performed to confirm the linear flaws. Metallurgical failure analysis showed that the cracks initiated from the inside diameter surface, were axially oriented and were intergranular or interdendritic in nature. The conclusion of the metallurgical analysis was that the nozzle flaws were caused by PWSCC in the nozzle to safe end weld [1]. In accordance with ASME Code Case N-504-2 [3], weld metal is applied circumferentially around the pipe in the vicinity of the flawed weldment to restore ASME Code Section XI margins. An analysis of the repaired weldment is performed using paragraph (g) of the Code Case as guidance to assure that the remaining flaw will not propagate unacceptably. According to ASME Code Case N-504-2, the weld overlay is to be designed to maintain all structural requirements assuming that a through-wall defect has penetrated 3600 of the pipe circumference. The weld overlay provides a replacement pressure boundary and an effective barrier to any further crack growth because of the excellent corrosion resistance inherent in the chemistry of deposits with ERNiCrFe-7 (Alloy 52) bare wire filler material or the ENiCrFe-7 (Alloy 152). Alloy 52 nickel-based weld repair material will be used rather than austenitic stainless steel as required by ASME Code Case N-504-2. All welding was accomplished using the automated machine gas tungsten arc welding (GTAW) process. Manual GTAW was used for final contour build-up. ASME Section m was used to provide guidance for repair inspection and post welding heat treatment requirements [2]. Weld overlay repairs were first applied to address intergranular stress corrosion cracking (IGSCC) in weld heat affected zones (HAZs) of boiling water reactor stainless steel piping as an alternative to pipe Background May 2005 WCAP-16428-NP Revision 1
2-2 replacement. Weld overlays have been used extensively in BWR stainless steel piping and safe-end weld repairs. This report will provide weld overlay design and qualification for the nozzle to safe end weld for the Westinghouse Model D Series 84 Pressurizer safety nozzle (Figures 2-1 and 2-2). Weld overlays have been used extensively in BWRs to repair flawed weldments since 1982 and have been shown to produce favorable compressive residual stresses on the inner portion of the pipe wall [5], which minimizes further crack growth. Many BWR weld overlay repairs were applied using stainless steel. However, in recent years, Alloy 52 has been used. Background May 2005 WCAP-16428-NP Revision I
2-3 NOZZIES (4 SPRAY NOZZLE SH IIW NOZZLE \ fiHc w PW Heater Sleeve Figure 2-1 Westinghouse Pressurizer Configuration Background May 2005 WCAP-16428-NP Revision 1
24 Carbon Steel Nozzle Stainless Steel Safe-end Stainless Steel Pipe SA216, Grade WCC SA182 Grade F316 SA1 82 Grade F316 Figure 2-2 Pressurizer Safety Nozzle Geometry for the Cast Head Configuration Background May 2005 WCAP-16428-NP Revision I
3-1 3 WELD OVERLAY DESIGN METHODOLOGY The evaluation of the overlay thickness was calculated in accordance with ASME Section XI Rules for Inservice Inspection of Nuclear Power Plant Components, IWB-3640 [9], to ensure that the pressurizer safety nozzle weld overlay will provide a structural barrier that is reliable and durable, along with the guidelines of ASME Code Case N-504-2 for structural weld overlays. It is assumed that the crack is 3600 in circumference, and through-wall. 3.1 DESIGN CRITERIA The weld overlay was designed as a full structural weld in accordance with the requirements of ASME Code Case N-504-2 [3]. The overlay will extend around the full circumference of the safe-end for the required length and thickness. In accordance with ASME Section XI, IWB-3640 [9], the maximum allowable depth (a,) for axial and circumferential flaws on the inside surface is 75 percent of the wall thickness. However, the actual allowable flaw size must be calculated in accordance with ASME Section XI Appendix C. For this case an allowable of 75 percent through-wall can be used, therefore the required repair thickness can be defined by: t 0.75 (t+h) Where: t = wall thickness at the location of indication, 1.405 inches h = thickness of weld overlay repair, 0.468 inches For circumferential flaws the overlay length and end slope of the reinforcement is sufficient to provide for load redistribution from the pipe into the deposited weld metal and back into the pipe without violating applicable stress limits of Section III. The length should extend axially at least 0.75Rt beyond each end of the observed flaws, where R and t are the outer radius and nominal wall thickness of the pipe/nozzle, prior to deposition the weld overlay, and the end slope should be no steeper than 45 degrees [3]. For axial flaws, as in this case, such reinforcement is not necessary, as Code Case N-504-2 states that the axial length of the weld overlay shall cover the weldments and the heat affected zone on each side of the weldments, with a minimum overlap of 1/2 in. on each end of the observed flaws. The weld overlay repair is to be applied 360° around the component to provide a full structural barrier. The repair design is shown schematically in Figure 3-1. 32 NOZZLE SAFE-END WELD OVERLAY DESIGN To avoid any stress risers and to allow for future inspections, the weld material is extended and tapered across the pipe and nozzle side. Therefore, the length of the actual weld overlay exceeds the minimum length required by ASME Code Case N-504-2 for load redistribution. It is important to note that the Weld Overlay Design Methodology May 2005 WCAP-16428-NP Revision 1
3-2 inspection requirements are a controlling factor in weld overlay repair design. The length of the weld overlay must be sufficient for inspection of an area that is 1/2 inch beyond the required repair length and covers the outer 25% of the original wall thickness. Any geometric transitions must be gradual and the surface sufficiently smooth for proper operation of the inspection probe. The design shown in Figure 3-1 is considered inspectable based on current industry inspection techniques. As indicated in the weld overlay design drawing (Figure 3-1), the design shows the minimum required thicknesses to meet the code case requirements. The cross-hatch sections indicate the structural requirements for the overlay repair, the gray area represents weld deposits that were added to facilitate inspection needs. The weld overlay design values (thickness and length) supplied in this report are considered minimum acceptable values. Additional passes or a larger thickness will not invalidate the original analysis. The minimum thickness for the safety nozzle to safe end weld overlay repair is 0.468" with additional layers for dilution. The weld overlay repair extends over the safe end to pipe weld as well, for inspectability reasons. The weld overlay in this region is also thick enough to qualify as a structural overlay. The thickness of the weld overlay at this location is approximately 0.48", in addition to the original thickness of 0.715". Weld Overlay Design Methodology May 2005 WCAP-16428-NP Revision I
3-3 a,c,e Figure 3-1 Westinghouse Pressurizer Safety Nozzle Weld Overlay Design Weld Overlay Design Methodology May 2005 WCAP-16428-NP Revision I
4-1 4 MATERIAL PROPERTIES 4.1 MATERIALS Typically, the material for the safe end and stainless steel piping are assumed to be the same. For this safety nozzle, the material of the safe end and stainless steel piping is SA 182 Grade F-3 16 [15]. The safe end to nozzle weld is Alloy 82/182 [15], the pressurizer nozzle and shell is ASME SA-216 Grade WCC [15]. 4.2 WELD OVERLAY MATERIAL PROPERTIES [
] ce Material Properties May 2005 WCAP-16428-NP Revision 1
4-2 Table 4-1a Material Properties for Stainless Steel a,c,e Table 4-1 b Stress-Strain Values for Stainless Steel a,c,e Material Properties May 2005 WCAP-16428-NP Revision I
4-3 Table 4-2a Material Properties for SA 216 Grade WCC Property 70 F 200 F 400OF 600F 800F IOOO F 1200F 14000F 1600F 18000 F 20000 F 22001F 2400"F 2500OF Coeflicient of ALPX Thentma (infAn/ F) 6.50E-6 6.67E-6 7.07E-6 7.42E-6 7.76E-6 8.12E-6 8.48E-6 8.83E-6 - Expansion (nrl ) KXX Conductivity (Btu/hr-ft- 35.1 33.6 30.9 28.0 25.2 22.4 19.5 16.4 - - Modults of EX 29.5E6 - 26.7E6 - - 21.8E6 - 17.4E6 14.3E6 b (sticit C Specific Heat (BTU/Ibm- 0.105 0.114 0.125 0.134 0.147 0.165 0.186 0.415 - - - - Poisson's Ratio NUXY 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Density DEbsNi?) 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 0.279 Table 4.2b Stress-Strain Values for SA 216 Grade WCC a,c,e Material Properties May 2005 WCAP-16428-NP Revision I
4-4 Table 4-3a Material Properties for Alloy 690, 600 a,c,e Table 4-3b Stress-Strain Values for Alloy 690, 600 a c,e I -7 Material Properties May 2005 WCAP-16428-NP Revision I
5-1 5 WELD OVERLAY FINITE ELEMENT ANALYSIS 5.1 OBJECTIVE OF THIE ANALYSIS The objective of this analysis is to determine stresses produced by a safety nozzle weld overlay repair and to evaluate the stresses for the Section XI requirements. This includes analysis to simulate the weld repair process to evaluate residual weld stresses. These analyses were performed using the ANSYS 7.1 finite element analysis program [6]. The plant specific geometry of the safety nozzle [15] was used to create the finite element model used in the analysis. Crack growth evaluations were performed using the stress results to show that the overlay is sized adequately and within allowable crack growth limits. 5.2 MODEL The model was developed to capture the parts of the structure which are critical to the safety nozzle. This includes a portion of the pressurizer shell attached to the safety nozzle and a length of stainless steel pipe attached to the safe end. The overall model is shown in Figure 5-1. The pressurizer shell is fixed in the rotated axial (Y) direction to simulate the rest of the pressurizer shell. The stainless steel piping is coupled in the axial direction to simulate the remaining stainless steel piping material not included in the model. The model uses PLANE42 for the structural elements and PLANE55 for the thermal elements, each with 4 nodes. The model is axisymmetric and uses isotropic, temperature dependent material properties as summarized in Section 4. Higher order elements are not used in this application because the plasticity treatment in the elements does not derive a significant benefit of the higher order shape functions. The typical analysis sequence involves a heat transfer analysis which determines applicable heat flow and temperatures (steady state or transient). The same model is used, with the element type switched from PLANE55 to PLANE42 and appropriate structural boundary conditions applied. The nodal temperatures are read into the structural model to capture the steady state or transient thermal stresses.
] ace 5.3 WELD REPAIR SIMULATION AND DESIGN LOAD ANALYSIS An analysis was performed to determine residual weld stresses in the repaired safety nozzle butt weld regions, to support the ASME Section XI evaluations. [
]
Stress Analysis May 2005 WCAP-16428-NP Revision I
5-2 [] The structural analysis used a similar process. [
]X¢-'The final residual weld stresses, at normal operating conditions are shown in Figures 54 through 5-7 (The percentage through wall indicated in Figures 54 through 5-7 is equal to the original wall thickness at 100%, beyond which point is the weld overlay). The general trend of these plots indicates compressive stresses at the inside surface of the nozzle due to the weld overlay repair and tensile stress at the outside surface of the nozzle and the weld overlay. This is consistent with industry experience of weld overlay repairs.
The weld cut locations for which the through-wall stresses were taken can be found in Figure 5-3. Contour plots of the weld overlay were taken in the hoop and axial directions at the final operating and ambient condition time steps. These nodal stress plots average the results across the weld overlay boundary. Figures 5-8 and 5-9 provide the stress contours at ambient conditions, which indicates compressive stress on the inside surface of the both the stainless steel and Inconel welds. Figures 5-10 and 5-11 provide the stress contours at operational conditions, which also indicates that the inside surface of the nozzle experiences compressive stress due to the weld overlay repair. Stress Analysis May 2005 WCAP-16428-NP Revision 1
5-3 i ANSY> y x Figure 5-1 Axisymmetric Finite Element Model Used for Safety Nozzle Weld Overlay Analysis Stress Analysis May 2005 WCAP-16428-NP Revision 1
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;;-LELLM (Ele=hs Figure 5-2 Model of Weld Overlay Segments for the Safety Nozzle Weld Overlay Stress Analysis Stress Analysis May 2005 WCAP-16428-NP Revision I
5-5 ANYS> Stainless Steel Weld Cut Inconel Weld Cut
\I I Nozzle Safe End Stainless Steel Pipe x
y Figure 5-3 Limiting Sections of Safety Nozzle Weld Overlay (Stress Paths for Figure 5-4 through 5-7) Stress Analysis May 2005 WCAP-16428-NP Revision I
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beyond which point is the weld overlay Stress Analysis May 2005 WCAP-16428-NP Revision 1
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- Note, the percent through wall indicated on the X-axis is equal to the original wall thickness at 100%,
beyond which point is the weld overlay Stress Analysis May 2005 WCAP-16428-NP Revision 1
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6-1 6 CRACK GROWTH ANALYSIS
6.1 INTRODUCTION
The effectiveness of a weld overlay repair with Alloy 52 weld material is demonstrated using crack growth analysis, to ensure that the weld overlay does not deteriorate during service. Using the residual stresses developed by the finite element model of the weld overlay process, future crack growth was evaluated for the safety nozzle safe-end location, considering fatigue crack growth, using the key operational transients which affect the region. The weld metal, Alloy 52, is the material used in weld overlay repairs for the safety nozzle safe-end. The advantage of this alloy is its highly resistant nature to TGSCC and PWSCC, so there was no need to evaluate future stress corrosion cracking. The fatigue crack growth calculations were carried out assuming that the original pipe section is cracked through. 6.2 ALLOWABLE FLAW SIZE DETERMINATION The critical flaw size is not directly calculated as part of the flaw evaluation process for stainless steels or nickel-base alloys [10]. Instead, the failure mode and critical flaw size are incorporated directly into the flaw evaluation technical basis, and therefore into the tables of "Allowable End-of-Evaluation Period Flaw Depth to Thickness Ratio," which are contained in paragraph IWB-3640. A more accurate determination of the allowable depth can be made using the methodology of ASME Section XI, Appendix C [9]. The allowable flaw sizes of paragraph IWB-3640 for the high toughness base materials were determined based on the assumption that plastic collapse would be achieved and would be the dominant mode of failure. In perforning the analyses necessary to determine allowable flaw depths and fatigue crack growth for the flaw evaluations, it is important that all the applicable loadings are considered, nozzle loads at the safety nozzle location can be found in Table 6-2. All repair welding was accomplished using automated machine gas tungsten arc welding (GTAW) process. Therefore, Appendix C of the ASME Code Section XI was used for the evaluation. Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-2 6.3 PRESSURIZER SAFETY NOZZLE TRANSIENTS AND PIPING LOADS The design transients and the number of occurrences of these transients over the design life of the components are required to perform fatigue crack growth analysis. The design transients for typical Westinghouse Series 84 Pressurizer safety nozzle are contained in Table 6-1. Table 6-1 Summary of Transients Number of Number Transient Identification Occurrences Normal Conditions I Heatup and cooldown 200 2 Unit loading 18,300 3 Unit unloading 18,300 4 Large step load 4,200 Upset Conditions 5 Loss of load 480 6 Loss of power 40 7 Loss of flow 80 8 Inadvertent spray 10 9 OBE 400 Test Conditions 10 Leak test 50 The loading conditions which were evaluated include thermal expansion (normal and upset), pressure, deadweight, seismic (OBE), and valve thrust. The piping loads used in the evaluation are listed in Table 6-2. The stress intensity values were calculated using the following equations:
= FM A (6-1) ab= [M2+M2.5 where:
F. = axial force component (membrane) My, MZ = moment components (bending) A = cross-section area Z = section modulus Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-3 Table 6-2 Pressurizer Safety Nozzle Loads (X - North, Y- Vertical Up, Z - East) [131 F. (lb) Fy (lb) F. (lb) Mj(in-lb) Ml(in-lb) MN(in-lb) Deadweight 20 -1040 60 18230 -950 -11150 Max. Thermal -140 -2069 -690 -28480 26920 -64200 Max. OBE 1031 1523 852 18491 18177 33944 Max. Valve Thrust 2230 3985 1460 44943 31261 48836 6.4 STRESS CORROSION CRACK GROWTH Longitudinal or axial flaws result from hoop stresses such as pressure, thermal transient loading, and residual stresses. Therefore, only hoop stress due to residual, transient loading, and pressure stresses were considered. The finite element analysis shows the residual stress [Section 5] produced during the repair process is significantly compressive on the inside surface of the pipe. Even when the hoop stress due to pressure is superimposed on the residual stress, the total stress on the inside surface of the pipe remains compressive. This results in a negative stress intensity factor -50% through the wall. Since PWSCC does not occur under compressive stress, the overlay repair mitigates PWSCC for axial flaw. A circumferential flaw, on the other hand, is caused by axial stresses from pressure loads, thermal transient loads, and residual stresses. The axial residual stress is also compressive at the inside surface of the pipe. In comparison to the normal operational loads, the residual stresses are much higher. Therefore, PWSCC of the postulated circumferential flaw is not expected. Thus, if only PWSCC were being considered, no growth of either axial or circumferential flaws would be expected. The weld overlay material is Alloy 52, which is applied to the both stainless steel weld and the Inconel weld on the safe-end. In nickel base alloys (Alloy 52 or 690) there are no ferrites, and the PWSCC resistance comes from the high level of chromium in the alloy. Therefore, the initial layer can be retained as PWSCC resistant provided the chromium level is sufficient. When diluted with carbon steel, the chromium level of the diluted first layer produced by an Alloy 52 weld overlay is expected to be less than 25% since the carbon steel does not contain chromium. The chromium level of the deposit should approach 25% by the second layer of weld material, thereby producing a deposit that is resistant to PWSCC. However, neither layer is credited towards the weld overlay repair for added conservatism. PWSCC growth of an axial or circumferential flaw will not occur and will not penetrate the original pipe wall due to the significant compressive residual stress from the weld overlay repair process. Considering the improbable scenario where PWSCC is not fully mitigated, the likelihood of PWSCC growing beyond the original pipe wall is negligible due to the highly resistant Alloy 52 material. This conclusion is consistent with similar results for BWR weld overlay. Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision I
6-4 6.5 FATIGUE CRACK GROWTH The fatigue crack growth analysis procedure involves postulating an initial flaw at the regions of concern. In this case, the initial postulated flaw is equal to the original wall-thickness, 1.405 inches for the Inconel weld location and 0.715 inches for the stainless steel weld location. The postulated flaws are subject to cyclic loads due to transients. The input required for a fatigue crack growth analysis is basically the information necessary to calculate the parameter AK1 (range of stress intensity factor), which depends on the crack size, crack shape, geometry of the structural component where a crack is postulated, and the applied cyclic stresses. The transients considered in the analysis are the design transients for typical Westinghouse Series 84 Pressurizer at the safety nozzle location, as shown in Table 6-1. The transient stresses were combined with through-wall residual stress distribution from the finite element analysis to determine AK,. Once AK, is calculated, the growth due to a particular stress cycle can be calculated by an equation developed from References 11, 17, and 18. This incremental growth is then added to the original crack size, and the analysis proceeds to the next cycle or transient. The procedure is continued in this manner until all of the analytical transients predicted to occur in the remaining design life of operation have been analyzed. The fatigue crack growth is calculated by computer program FCG Reference [4]. Fatigue Crack Growth Rate Reference Curves for Alloy 52 The fatigue crack growth rate reference curve for these nickel base alloys was obtained from the literature. The material properties of Alloy 600 and Alloy 52 are very similar, therefore it is assumed the crack growth rate of Alloy 600 can be applied to Alloy 52. The crack growth rate is a function of both R Ratio (Ki,,/E) and the range of applied stress intensity factor. Using the results reported in References 19 through 22, a model was developed for application to water environment, as shown below. _ = CSRSEJVAKM (6-2) where: C = 4.835x 10-14 + 1.622x10'- 6 T -1.A90x 10-'T 2 + 4.355x 10-21 T3 SR = [1- 0.82R I22 SENv =1+A[CSRAKVr TR A=4.4x10-7 m = 0.33 n=4.1 where: T= C AK = MPaFm-eer R = K m. I Kxt Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-5 This model was proposed by Chopra et al in Reference 22, and was judged to be conservative for this application, as it includes data for water environments with Oxygen contents up to 10 ppb, as shown in Figure 6-1. The typical PWR water chemistry has an Oxygen level which is too low to measure, since it is scavenged by the presence of a Hydrogen overpressure. This factor was accounted for by the choice of a rise time of 30 seconds for the model.
&!i - '-" "III I &alq i b4 laA I I -i .I laaJj I}
Aloy 600 132C 3**2*0C ,. **, 6 r?0-1 0 C.) 10.11 10112 1012 l01'l-l CGRair (fts) Figure 6-1 Fatigue Crack Growth Model Development for Water Environment Fatigue Crack Growth Rate Reference Curves for Stainless Steel The reference crack growth law used for the stainless steel appears in Section XI, Appendix C (1989 Edition, Figure 6-2) for air environments and its basis is provided in Reference 12. For water environments, an environmental factor of 2 was used, based on the crack growth tests in PWR environments reported by Reference 14. Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision I
6-6 da (6-3)
- = C.S AK,"
dN da where: dN = crack growth rate, inches per cycle 1 2 3 CO= material coefficient (Co = 1[ -0009 + 3.12E-04T-1.13E-06T +1.o2E-09T ]) S = (S = 1.0 for R=O; S=1+1.8R for O<R<0.79; S = -43.35+57.97R, for 0.79<R<1.0) n = material property slope (=3.30) AK,= stress intensity factor range, ksi% Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-7 ioxir' - z_ ________ 2l7 Z1 Solid hA4 WIF /0 / Dbsd Ns for SSW J to-4 = == I II _ __ ___ __ / - aturM._ _ 10~~~~~~~ _-_.10 2 _(b C _ _O l~ _*_ ~_ ~ ~ ep Mr _ _ FO, A C 7T1II AIW SAzNES STEL N I ENVIRONMENTS Figure 6-2 Reference Crack Growth Rate Curves for Stainless Steel in Air Environments 1121 Fractre Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision I
6-8 The results of the fatigue crack growth analysis indicate that crack growth is non-existent for the Alloy 82/182 weld location even after 40 years of service, as shown in Table 6-3 and Table 6-5 for axial and circumferential flaws, respectively. The evaluation was carried out using an initial flaw size equal to the original wall thickness (1.405"), not accounting for any remaining ligament This is due to the high compressive stresses produced during the repair process. The crack growth evaluation shows that the compressive residual stresses from the weld overlay repair is sufficient to mitigate any further crack growth. Fatigue crack growth is insignificant for the stainless steel weld location after 40 years of operation, as shown in Table 6-4 and Table 6-6 for axial and circumferential flaws, respectively. This is also due the high compressive residual stresses. Although no cracking was found in this location, an initial flaw size equal to the original wall thickness (0.715") was used for the evaluation. In addition, to fulfill inspection requirements, the weld metal deposited at this location is beyond code requirements for structural weld overlay therefore providing a higher flaw tolerance allowable to this region if any cracking is to occur. Table 6-3 Fatigue Crack Growth Results for Safety Nozzle Safe-End Inconel Weld Location, Axial Flaw Time (years) Aspect Sien- l 30 l 4 Ratio Initial Flaw 10 20 30 40 Size (in.) 2 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 3 1.405 14050 (in.) 14050 (in.) 14050 (in.) 14050 (in.) 6 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 10 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 100 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) Table 6-4 Fatigue Crack Growth Results for Safety Nozzle Safe-End Stainless Steel Weld Location, Axial Flaw Time (years) Aspect Ratio Initial Flaw 10 20 30 40 Size (in.) 2 0.715 0.7150 (in.) 0.7151 (in.) 0.7151 (in.) 0.7152 (in.) 3 0.715 0.7 152 (in.) 0.7153 (in.) 0.7155 (in.) 0.7156 (in.) 6 0.715 0.7155 (in.) 0.7160 (in.) 0.7165 (in.) 0.7170 (in.) 10 0.715 0.7159 (in.) 0.7169 (in.) 0.7178 (in.) 0.7187 (in.) 100 0.715 0.7173 (in.) 0.7196 (in.) 0.7219 (in.) 0.7243 (in.) Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-9 Table 6-5 Fatigue Crack Growth Results for Safety Nozzle Safe-End Inconel Weld Location, Circumferential Flaw Time (years) Aspect Ratio Initial Flaw 10 20 30 40 Size (in.) 2 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 3 1.405 14050 (in.) 14050 (in.) 14050 (in.) 14050 (in.) 6 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 10 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 100 1.405 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) 1.4050 (in.) Table 6-6 Fatigue Crack Growth Results for Safety Safe-End Stainless Steel Weld Location, Circumferential Flaw Time (years) Aspect Ratio Initial Flaw 10 20 30 40 Size (in.) 2 0.715 0.7150 (in.) 0.7150 (in.) 0.7150 (in.) 0.7150 (in.) 3 0.715 0.7150 (in.) 0.7150 (in.) 0.7150 (in.) 0.7150 (in.) 6 0.715 0.7151 (in.) 0.7152 (in.) 0.7153 (in.) 0.7153 (in.) 10 0.715 0.7153 (in.) 0.7155 (in.) 0.7158 (in.) 0.7160 (in.) 100 0.715 0.7160 (in.) 0.7170 (in.) 0.7181 (in.) 0.7191 (in.) 6.6 STRESS REPORT RECONCILIATION The addition of the weld material (approximately 50-60 pounds) is small in comparison to the weight of the piping, nozzle, and safe end. Therefore, the nozzle moments, deadweight, and seismic stresses with respect to primary stresses will not be significantly affected. Hence, the current stress analysis of the nozzle and piping will not be significantly impacted by the added weld mass. It is not required by ASME Code Case N-504-2 to evaluate the primary stresses nor the primary plus secondary stresses for the safety nozzle weld overlay repair. However, to assess the general impact of the weld overlay on the safety nozzle, finite element analysis were performed for the nozzle/safe end region using models both with and without the overlay repair. The intent of this evaluation is to conduct a Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
6-10 comparative study to assess whether the weld overlay increases or decreases the applicable safety nozzle hoop and axial stresses, and not to perform a fatigue analysis. If the stresses are about the same or reduced with the weld material, the original stress reports will be valid for the primary plus secondary stress limits, and no further reconciliation of the ASME code design analysis is required. For the pressure loading case, the total stresses are lower for the model with the weld overlay than without due to the increase in wall thickness. However, the thermal stresses were higher, due to the dissimilar metal weld. Therefore the pressure plus thermal stresses are higher for the model with weld overlay than without The results indicate that the primary stresses are lower, however, the secondary and the primary plus secondary stresses resulting from a safety nozzle weld overlay repair will be higher than in the original safety nozzle. Even though primary plus secondary stresses are higher now than before the application of the weld overlay, a comparison of the usage before and after the weld overlay is not necessary because the previously described fatigue crack growth analysis can be used to qualify the fatigue status. Shrinkage effects due to weld overlay repair were considered using the ANSYS finite element model. A node on the inside surface and at the end of the stainless steel pipe (but removed from the constraints) was chosen to demonstrate the axial displacement of the safety nozzle. The axial displacement (UY) of the stainless steel pipe will determine effects on piping loads. A node on the inside surface of the safe-end was chosen to demonstrate the radial displacement (UX) of the safety nozzle. The displacement of these two locations can be seen in Table 6 -7. Due to the insignificant change in both axial and radial displacement, shrinkage effects were deemed negligible. In addition, the overlay is blended smoothly to the nozzle interface as well as the stainless steel pipe interface to reduce any stress intensification. Table 6-7 Safety Nozzle Axial and Radial Displacements Due to Weld Overlay Repair Displacement Displacement Location Orientation (inches) Inside Surface of -0.0211 Stainless Steel Pipe Inside Surface of Radial 0.0237 Safe-end Radial_______ _ 0___0237 ___ Fracture Mechanics Crack Growth Analysis May 2005 WCAP-16428-NP Revision 1
7-1 7 WELD OVERLAY ACCEPTANCE INSPECTION The final requirement of Code Case N-504-2 is a UT inspection of the weld overlay. Since the overlay extends over both the Alloy 182/82 weld and the stainless steel weld, both were investigated, as well as the overlay itself. The inspectability of the entire region was improved by the overlay process, because it produced a smoother surface on the outside of the nozzle than the original surface. The overlay was found to be defect-free, a remarkable achievement compared to previous overlays, which typically have I 5 to 20 indications to be resolved. A small area of lack of fusion was identified between the overlay and the nozzle, but it was acceptable to the standards of Section XI, IWB-3500. As part of the acceptance inspection, the stainless steel weld was scanned, and an additional indication was found in that weld [24]. The UT determined wall thickness at this location was 0.75 inches, and the indication was axially oriented, and was not surface breaking. The through-wall dimension was 0.29 inches, with a ligament of 0.09 inches between the indication and the ID surface. This qualified the indication as embedded, according to the criteria of Section XI. The indication was found to be nearly circular, as its width was 0.30 inches. This indication can be evaluated for acceptability using the flaw acceptance criteria of IWB-3640, but the weld overlay repair extends over this region, as discussed in Section 3, and so it has already been repaired. Therefore, the additional indication has already been dealt with, and no further action is necessary. Weld Overlay Acceptance Inspection May 2005 WCAP-16428-NP Revision I
8-1 8
SUMMARY
The pressurizer safety nozzle weld overlay design was based on the requirements of Code Case N-504-2 and ASME Section XI IWB-3640. Both finite element stress analysis and fatigue crack growth showed that the repair meets the appropriate requirements. In accordance to ASME Code Case N-504-2, the minimum weld overlay thickness for the safety nozzle is 0.468 inches, not including dilution or sacrificial layers. The weld overlay design values (thickness, number of passes) supplied in this report are considered minimum acceptable values. Additional passes or a larger thickness will not invalidate the original analysis. The use of Alloy 52 weld material is widely accepted in the industry for its stress corrosion resistant property and along with the GTAW process will further reinforce the effectiveness of a structural weld overlay repair for the safety nozzle. The weld residual stress was demonstrated to provide a favorable stress field to mitigate PWSCC. The finite element analysis performed showed that the weld overlay repair results in a compressive stress field on the inside surface of the pipe, essentially eliminating the potential for any axial or circumferential crack propagation. The compressive residual stress also dramatically reduced the potential for fatigue crack growth to occur. The added thickness to the nozzle safe end will further ensure the structural integrity of the safety nozzle due to the weld overlay repair. Consequently, the weld overlay repair method is a viable PWSCC mitigation and repair method, and has demonstrated to have many successful repairs in previous applications. Summary May 2005 WCAP-16428-N? Revision 1
9-1 9 REFERENCES
- 1. NRC Information Notice 2004-11, "Cracking in Pressurizer Safety and Relief Nozzle and in Surge Line Nozzle," W. D. Beckner, May 6, 2004.
- 2. ASME Boiler and Pressure Vessel Code, Section m, "Rules for Construction of Nuclear Power Plant Components", 1965 Edition, Winter 1966 Addendum.
- 3. ASME Section XI Code Case N-504-2, "Alternative Rules for Repair of Class 1, 2, and 3 Austenitic Stainless Steel Piping", March 1997.
- 4. C. Y.Yang, "Verification and Validation of FCG 5.3, Rev. 0", CN-PAFM-03-33, 02/04/2004.
- 5. NUREG-0313, Revision 2, "Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping", U.S. NRC, January 1988.
- 6. Westinghouse Letter, LTR-SST-03-57, "Release of ANSYS 7.1 on HPUX 11.22, XP, Solaris 2.8,"
October, 6 2003.
- 7. ASME Boiler and Pressure Vessel Code, 2001 Edition, through 2003 Addenda, Section II Materials Part D - Properties.
- 8. ASME Boiler and Pressure Vessel Code, 2001 Edition, through 2003 Addenda, Section II Materials Part C - Specifications for Welding Rods, Electrodes, and Filler Metals.
- 9. ASME Boiler and Pressure Vessel Code, Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components", 1998 Edition.
- 10. "Evaluation of Flaws in Austenitic Steel Piping," Trans ASME Journal of Pressure Vessel Technology, Vol. 108, August 1986, pp. 352-366.
- 11. Raju, I. S. and Newman, J. C., "Stress Intensity Factor Influence Coefficients for Internal and External Surface Cracks in Cylindrical Vessels" in Aspects of Fracture Mechanics in Pressure Vessels and Pipni. ASME publication PVP. Vol. 58, 1982.
- 12. James, L. A., and Jones, D. P., "Fatigue Crack Growth Correlations for Austenitic Stainless Steel in Air," in Predictive Capabilities in Environmentally Assisted Cracking," ASME publication PVP-99, Dec. 1985.
- 13. Teledyne Engineering Services Technical Report, TR-5364, "Analysis of Pressurizer Safety Valve Discharge Piping System, With Drained Loop Seals Per NUREG 0737, II. D.1, Unit 1, Revision 0", July 1983.
- 14. Bamford, W. H., "Fatigue Crack Growth of Stainless Steel Piping in a Pressurized Water Reactor Environment," Trans ASME Journal of Pressure Vessel Technology, Feb. 1979.
References May 2005 WCAP-16428-NP Revision I
9-2
- 15. Westinghouse Drawing No. 5D65245, Sheet 1, 2, and 3, Rev. 1, "Pressurizer Safety and Relief Nozzle Configurations."
- 16. EPRI NP-7103-D, Project T303-1, Topical Report, "Justification for Extended Weld-Overlay Design Life," January 1991.
- 17. Buchalet, C. and Bamford, W. H., "Stress Intensity Factors for Continuous Surface Flaws in Reactor Pressure Vessels" in Mechanics of Crack Growth ASTM STP 590 pp. 385-402, 1976.
- 18. Shah, R. C. and Kobayashi, A. J., "Stress Intensity Factor for an Elliptical Crack Under Arbitrary Loading," Engineering Fracture Mechanics, Vol.3, 1981, pp. 71-96.
- 19. James, L.A., and Mills, W.J.,"Fatigue Crack Propagation Behavior of Wrought Alloy 600 and Weld-deposited EN82H in an elevated Temperature Aqueous Environment," in ASME publication PVP Vol. 303, 1995.
- 20. Van Der Sluys, W.A., Young, B.A., and Doyle, D., "Corrosion Fatigue Properties of Alloy 690 and some Nickel-based Materials," in ASME publication PVP Vol.410-2, 2000.
- 21. Amzallag, C., Baudry, G., and Bernard, J.L., "Effects of PWR Environment on the Fatigue Crack growth of Different Stainless steels and Inconel Type Alloy," in Proc. Intnl. Atomic energy Agency Specialists Meeting on Subcritical Crack Growth, in NUREG/CP oo44, Vol 1, 1983.
- 22. Chopra, O.K., Soppet, W.K., and Shack, W.J., "Effects of Alloy Chemistry, Cold Work, and Water Chemistry on Corrosion Fatigue and Stress Corrosion Cracking of Nickel Alloys and Welds,"
NUREG/CR 6721, April 2001.
- 23. Hartz, L. N., "Needed Action for Visual Inspection of Alloy 82/182 Butt Welds and Good Practice Recommendations for Weld Joint Configurations," MRP 2004-05, April 2, 2004.
- 24. Cook Unit I Condition Report CR05117045, April 2005.
References May 2005 WCAP-16428-NP Revision 1
Attachment 4 to AEP:NRC:6055-03 DRAWINGS ILLUSTRATING THE WELD CONFIGURATION AND FLAW LOCATION The component labeled "Stainless Steel Pipe" in the first drawing is the same component labeled "Stainless Steel Elbow" in the second drawing.
Carbon Steel Nozzle Stainless Steel Safe-end Stainless Steel Pipe SA216, Grade WCC SA182 Grade F316 SA182 Grade F316 Pressurizer Safety Nozzle Geometry for the Cast Head Configuration
12 EHP 5040.PWD.001, PLANT WALKDOWNS Data Sheet 2, Field Data Walkdown Sheet Page 3 of 3 A. rewed 0 n l) View Looking in the Circular Direction Cook Nuclear Plant 1-RC-9-O1F NOTE: This form is derived from 12 EHP 5040.PWD.001. It or a form similar to it may be used provided the content is consistent with the current revision of.that procedure.
Attachment 5 to AEP:NRC:6055-03 REACTOR COOLANT SYSTEM DESIGN TRANSIENTS - PROJECTION TO 60 YEARS
Donald C. Cook Nuclear Plant License Renewal Application Technical Information Table 43-1 RCS Design Transients-Projection to 60 Years Design Transient Number of Number of Projected Number Design Transients Logged of Transients at Transients as of 10/31/98 60 Years of Operation1 IUnit 1 Unit 2 Unit 1 Unit 2 Level A Limits (Normal) Heatup events 200 44 50 110 145 Cooldown events 200 44 49 110 142 Unit loading at 5% of full 18300 (U2) Not monitored. Since the units are base loaded, power per minute 11680 (Ul) the frequency of loading/unloading transients will be of the same order as the number of heatup and cooldown cycles. Therefore, this transient does not need to be tracked. Unit unloading at 5% of full 18300 (U2) Not monitored. See comment above. power per minute 11680 (Ul) 10% step load increase 2000 732 732 183 212 10% step load decrease 2000 572 572 143 166 Large step load decrease 200 1 0 3 0 with steam dump Feedwater cycling/hot 18300 Not monitored. I&M has modified the plant standby (secondary side) design and operations to preclude feedwater nozzle cracking from being a concern. Turbine roll test 10 0 0 0 Steady-state fluctuations Infinite NA NA NA Level B Limits (Upset) Loss of load 80 0 0 0 0 Loss of AC electrical power 40 3 2 8 6 Loss of flow in one loop 80 0 0 0 0 4.0 Time-Limited Aging Analyses Page 4.3-13
Donald C. Cook Nuclear Plant License Renewal Application Technical Information Table 4.3-1 (Continued) RCS Design Transients-Projection to 60 Years Design Transient Number of Number of Projected Number Design Transients Logged of Transients at Transients as of 10/31/98 60 Years of Operation1 Unit 1 Unit 2 Unit 1 Unit 2 Reactor trip 400 69.19 68.95 173 200 Operating basis earthquakes 400 0 0 0 0
- except RPV Operating basis earthquakes 200 0 0 0 0 - RPV Level C Limits None (Emergency)
Level D Limits (Faulted) Large reactor coolant pipe 1 0 0 0 0 break Steam line break 1 0 0 0 0 Safe shutdown earthquake 1 0 0 0 0 Test Conditions Primary side leak test 50 1 1 3 3 Hydrostatic test (primary) 5 1 1 3 3 Hydrostatic test (secondary) 5 1 1 3 3
- 1. Projected cycles = cycles as of 10/25/98
- 2.5 (Unit 1) or *2.9 (Unit 2). Numbers are rounded up to the nearest whole number. 2.5 = 60 years/24 years of operation for Unit I and 2.9=60 years/21 years of operation for Unit 2.
- 2. Only one value for both units.
4.0 Time-Limited Aging Analyses Page 4.3-14 to AEP:NRC:6055-03 DIT-S-01 504-00
r ffi AEP DESIGN INFORMATION TRANSMITTAL (DIT DrT Form, Part 1 Originating Organization ol05by 0 a 3 SAFETY-RELATED 0 AEP DIT No DIT-et50'3 lo .1 ~ E NON-SAFETY-RELATED ] Other (spefy) D.C. Cook Unit: 1 Page I of 3 System Designation RCS To Chris Ng, Westinghouse
Subject:
Provide ultasonic data from Weld l-RC-9-OIF exdnation for [WB-3600 analysis Paul Donavin Principal Engineer G o; 1_ Preparer Position Preparer's Signature Date Roy E. Hall ISI Program Owner S/Ic S/11 V05 Reviewer Position R Date Approver Position atrc Date Status of Information: ID Approved for Use 0 Unverified Method and Schedule of Verification for Unverified DITs NIA CR# N/A Holds Associated with Unverified DITs: None Description of Information: The attached field walkdown data describes the indication inthe subject weld. Purpose of Issuance (Including any Precautions or Lirnitations): The purpose of this information is to provide input to the IWB-3600 Analysis. Source of Information: Attached field walkdown report Engineering Judgement Used? E Yes 0 No Controlled Reference / Document No.: Uncontrolled Reference / Document No.: Distribution: Copy to Requestor Chris Ng, Westinghouse Copy to DIT Administrator File Original to NDM (Transmitted by DIT Administrator) This form is derived from the infornation in 12-EHP-5040-DES-001 Control of Design Input.
-DIT-5-0(St-{-00 4.
12 EHP 5040.PWD.001, PLANT WALKDOWNS Data Sheet 2, Field Data Walkdown Sheet Page 2 of 3 AEP DESIGN INFORMATION TRANSMITTAL (DIT) DIT Form, Part 2 FIELD DATA WALKDOWN (Use Continuation Sheets as required) SCOPE: (Describe the desired data to be collected. Provide component ID's, document references, plant locations, etc., as needed.) Provide data on the indication in Weld 1-RC-9-OIF including available dimensions and orientation Prepared by: (Print/Sign) -Paul Donavin / SKY) / c Date: 5/18/05 Data Flaw orientation and dimensional data (see attached sketch) in the fusion zone of 1-RC-9-OlF. uT- os - o067.
, A._^
_^%
,I Data Collected By:
Roy E. Hall Q<, E V ALL >CX'A.'roo W- 5118/05sloG s/h (Print Name/Signature) (Initials) Date Two-party Verification Performed By 5/18/05 Paul R. Donavin / _ (Print Name/Signature) (Initials) Date NOTE: This form is derived from 12 EHP 5040.PWD.001. It or a form similar to it may be used provided the content is consistent with the current revision of that procedure.
12 EHP 5040.PWD.001, PLANT WALKDOWNS Data Sheet 2, Field Data Walkdown Sheet Page 3 of 3 A. rgw-. 0 n) I fc View Looking in the Circular Direeton Cook Nudear Plant 1-RC-901F NOTE: This form is derived from 12 EHP 5040.PWD.001. It or a form similar to it may be used provided the content is consistent with the current revision of.that procedure.}}