ML071350646
| ML071350646 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 05/08/2007 |
| From: | Broussard J, Collin J, White G Dominion Engineering |
| To: | Office of Nuclear Reactor Regulation |
| Mensah T | |
| References | |
| Download: ML071350646 (132) | |
Text
Advanced FEA Crack Growth Calculations for Evaluation of PWR Pressurizer Nozzle Dissimilar Metal Weld Circumferential PWSCC Sponsored by: EPRI Materials Reliability Program Presented To:
Expert Review Panel for Advanced FEA Crack Growth Calculations Presented By:
Glenn White John Broussard Jean Collin Dominion Engineering, Inc.
Tuesday, May 8, 2007 11730 Plaza America Dr. #310 Status Meeting on Implications of Wolf Creek Dissimilar Metal Weld Inspections Reston, VA 20190 703.437.1155 Bethesda North Marriott Hotel and Conference Center www.domeng.com North Bethesda, Maryland
Topics Introductions - Industry and NRC Status of Industry work, including response to April 4, 2007 NRC letter - Industry Status of NRC Confirmatory Research - NRC Presentation & Discussion of Proposed Matrix - Industry Additional topics - Industry and NRC
- Critical Crack Size Calculations (if not covered in bullet 2) - Industry
- Validation studies and WRS mockups - Industry
- Benchmarking NRC/Industry K Solutions for the Advanced FEA Calculations -
Industry and NRC
- Leak-rate Calculations - Industry Plans for next meeting(s) - Industry and NRC Meeting Summary and Conclusions - Industry and NRC 2 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Principal Meeting Participants EPRI Project Management / Support NRC Participants
- Craig Harrington, EPRI - Al Csontos, NRC Research
- Tim Gilman, Structural Integrity Associates - Bob Hardies, NRC Research Project Team - Dave Rudland, EMC2
- Glenn White, DEI - Simon Sheng, NRC NRR
- John Broussard, DEI - Ted Sullivan, NRC NRR
- Jean Collin, DEI
- Greg Thorwald, Quest Reliability, LLC Expert Review Panel
- Ted Anderson, Quest Reliability, LLC
- Warren Bamford, Westinghouse
- Doug Killian, AREVA
- Pete Riccardella, Structural Integrity Associates
- Ken Yoon, AREVA 3 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Project Plan Phase II Calculations Perform detailed sensitivity studies, benchmarking, and validation work specific to the pressurizer nozzle DM welds in the 9 spring 2008 plants to evaluate the viability of leak before break for these welds
- Collection of geometry, loading, and weld repair data for 9 spring 2008 plants
- Background on fracture mechanics basis for stress intensity factor calculation
- Further software verification activities
- Treatment of welding residual stress
- Critical crack size calculation basis
- Setting and evaluation of matrix of sensitivity cases using cylindrical shell geometry
- Evaluation of effect of multiple flaws
- Model validation efforts
- Participation of industry and NRC experts to build consensus
- Probabilistic calculation to investigate likelihood that the Wolf Creek indications were really growing as rapidly as assumed in the White Paper and NRC calculations
- Final report with methodology, results, and validation in EPRI format 4 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Project Plan Additional Calculations with Crack Inserted into WRS Model Perform selected sensitivity cases with crack mesh inserted directly into three-dimensional welding residual stress FEA model:
- More precise calculation of stresses for nozzle-to-safe-end geometry
- Direct input of welding residual stresses from welding residual stress FEA model, rather than user selection of welding residual stress cases
- Consideration of secondary effects such as local thermal stresses due to difference in coefficient of thermal expansion for each material
- Because this modeling is more labor- and CPU-intensive compared to modeling using cylindrical shell geometry and residual stresses simulated via temperature field input, this model will be used to evaluate a subset of the full matrix of cases
- The cylindrical shell model also has the advantage of allowing direct comparison with published stress intensity factor solutions, including those considering the standard ASME welding residual stress assumptions 5 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Work Status Summary Assessment of plant-specific inputs for 51 welds in 9 spring 2008 plants
- Dimensions
- Piping loads
- Available weld repair information Critical crack size calculations
- Limit load calculations for through-wall flaws in 51 welds
- Limit load calculations for part-depth flaws in 51 welds
- Limit load calculations for custom crack profile (part-depth and through-wall)
- Assessment of EPFM failure mode Crack growth calculations for custom crack shape
- FEACrack software extensions
- Modeling refinements
- Effect of moment magnitude and initial crack assumption
- Stability of calculated crack progression
- Element and time step size refinement studies
- Use of WRC Bulletin 471 axisymmetric solution as scoping tool 6 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Work Status Summary (contd)
Leak rate calculations
- PICEP and SQUIRT models
- Calculation of COD and leak rate using PICEP as scoping tool
- Calculation of leak rate with COD from complex crack growth FEA calculations Development of matrix of WRS profiles
- Axisymmetric (self balance at every circumferential position)
- Non-axisymmetric (self balance over entire cross section)
Development of analysis case matrix Software verification and benchmarking Validation planning 7 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Work Status Software Development The status of the new FEACrack software modules by Quest Reliability, LLC is as follows:
- Growth of surface crack with custom profile (including with nodal repositioning routine): Issued
- Apply user-defined temperature distribution for the cylinder model with a text box "macro" input: Issued
- Implement rigid surface contact for crack face closure in the quarter symmetric cylinder: Issued
- Add custom 360° surface circ crack to mesh generator with custom crack growth in the fatigue growth module: Issued
- Implement fatigue crack growth for custom crack front profile for through-wall crack
(<360° on ID & 360° on ID): In progress
- New nozzle-to-safe-end geometry to facilitate placing crack into FEA WRS model:
May timeframe See presentation by Greg Thorwald of Quest Reliability, LLC for discussion of FEACrack software extensions 8 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
New and Future Features in FEACrack Greg Thorwald, Ph.D.
303-415-1475
Outline - FEACrack Features Recently Developed
Custom surface crack
Ansys macro text, input temperature gradient
Custom 360o crack
Node redistribution, fatigue analysis Future Development
Complex custom crack
Update custom through-wall crack
Nozzle to safe end geometry
Custom Surface Crack
Enter all crack front node coordinates
Any number of nodes, arbitrary spacing
All nodes updated during fatigue analysis
Custom 360o Crack
Enter all crack front node coordinates
- Any number of nodes, arbitrary spacing
- All nodes updated during fatigue analysis
Node Redistribution
An option for fatigue analysis
- helps avoid numerical problems at the crack tip
Nodes shift downward along the crack front
Relocate nodes on updated crack front to preserve the relative node spacing
Complex Custom Crack
Through-wall crack shape at the OD crack tip
Crack front curves to a part-depth crack along pipe ID
Use custom crack coordinates for all crack front nodes
Quarter symmetric model
Custom Through-Wall Crack
Custom through-wall crack is available
Test and update for custom crack fatigue analysis
- Update all crack front nodes during fatigue
- Slanted profile to continue fatigue analysis from surface crack results Slanted Profile Thumbnail Profile
New Nozzle Geometry Nozzle-to-safe-end geometry
Add to FEACrack geometry library
Automatically create the crack mesh in the nozzle geometry
Allow automated parametric analysis Source: MRP 2007-003 Attachment 1 (White Paper).
April 4, 2007, NRC Letter Comments on Crack Growth Calculation Comment #1. The industry incremented the crack growth in the analyses based on constant increment of crack growth in the length direction for the majority of the analyses.
This constraint caused the times for the crack extension at the surface and depth to be different. Even though these differences are small, over the entire time period the sum of the differences could be substantial. This difference could bring into question the validity of the crack shape at leakage. Growing the crack along the crack front by a constant time increment seems more logical and more representative of the crack growth physical characteristics. We suggest further investigation into the crack increment calculation is warranted.
Response. As discussed with the NRC on the April 9 conference call, this comment represents a misunderstanding of the crack increment calculation method. A standard fully explicit time stepping procedure is applied. In order to investigate the adequacy of the time step size in the Phase I calculation, an improved estimate of the elapsed time was calculated based on the crack growth rates from the stress intensity factor at the beginning and at the end of each time step. In the most recent industry work, we are explicitly decreasing the time step size to confirm time and crack profile convergence.
9 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Comments on Crack Growth Calculation Comment #2. In Figure 11 of industrys Phase I calculations on the evolution of the stress intensity factors, a discontinuity occurred after the second increment of crack growth, and appears to occur at the same stress intensity for each of the remaining steps. Industrys response to a question on this observation during the March 20, 2007, teleconference was unclear, but industry indicated they believed the response was real. We suggest further investigation into the mesh density or the crack increment calculation is warranted. It is recognized that this effect is probably secondary in nature.
Response. The observed behavior is a real effect in terms of the stress intensity factor being locally high where the crack front profile is not smooth. In recent work, DEI has concluded that this behavior observed in the draft Phase I calculation was an artifact of the crack growth increment size. Reducing the crack increment along the ID circumference results in a fully behaved stress intensity factor profile. The new results for the Phase I calculation inputs confirm that this issue in fact had a small effect on the crack profile at the point of through-wall penetration.
10 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 1: FEA FM Model Using FEACrack / ANSYS Symmetry Boundary Conditions Axial Force and Effective Total Moment Pressure Applied to Crack Face 8.0" Temperature profile applied to red 1.0" region to produce WRS profile 11 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Methodology Adjustments Mesh refinement changes to shift additional nodes at surface region of crack front Temperature loading adjustments and mesh refinement changes to improve through-wall stress distribution Crack shape study to develop more natural crack shape for initial size parameters Reduced crack growth / time increment
- 3X previous number of steps
- Maintains flaw shape stability during automatic crack growth
- Use new arbitrary depth ID circ flaw capability when flaw reaches 360°
- Ligament between crack ends conservatively eliminated instantaneously as partial-arc crack approaches 360° 12 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 2: WRS Distribution Assumption Based on ASME Data Temperature profile improved to match desired curve 70 60 Desired Crack Depth 50 180 Side 40 Axial Welding Residual Stress (ksi) 30 PRELIMINARY 20 10 0
-10
-20
-30 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Normalized Distance from ID Surface, (r-ri)/t 13 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 3: Assumed Axial Stress Loading for Crack Growth Identical load 60 case assumed 50 0° 22.5° as previous 45° 67.5° 90° 40
- Endcap 112.5° Axial Stress with Residual Stress (ksi) 135° pressure load 30 157.5° 180°
= 0° to 180°
- Dead weight force 20 and moment
- Pipe thermal 10 expansion force 0 and moment
- Assumed WRS -10 distribution -20
= 0° is circumferential position of maximum bending axial stress;
= 90° is bending neutral axis Crack face -30 pressure also 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 Normalized Distance from ID Surface, (r-ri)/t 0.80 0.90 1.00 applied 14 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 4: Axial Extent of Imposed Thermal Stress Simulating WRS Original Model Crack Side Stress Distribution Opposite Crack Side Stress Distribution 70,000 PRELIMINARY 60,000 50,000 40,000 Axial Stress (psi) 30,000 20,000 10,000 0
-10,000 0.00 0.50 1.00 1.50 2.00 2.50 3.00 Axial Distance (in) 15 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Methodology Adjustments Natural shape developed by growing semi-ellipse shape out to desired depth and length Initial Flaw for "Grown" Case "Grown" Flaw Shape Pure Semi-Ellipse Flaw Shape 0.4 PRELIMINARY 0.35 0.3 Crack Depth (in) 0.25 0.2 0.15 0.1 0.05 0
0 0.5 1 1.5 2 2.5 3 3.5 4 Circumferential Distance Along ID (in) 16 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Methodology Adjustments (contd)
Additional refinement and natural shape yield smoother crack tip SIF profile Initial Flaw for "Grown" Case "Grown" Flaw Shape Pure Semi-Ellipse Flaw Shape 40,000 FEA Stress Intensity Factor, K (psi-in0.5) 35,000 30,000 25,000 20,000 15,000 10,000 5,000 PRELIMINARY 0
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Relative Distance Along Crack Front from Deepest Point to Surface Point (--)
17 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 7: Growth Progression in Flat Plane 1.20 2c/a=20.9, a/t=0.260 2c/a=18.9, a/t=0.310 2c/a=18.4, a/t=0.342 2c/a=18.5, a/t=0.375 2c/a=19.0, a/t=0.395 2c/a=19.5, a/t=0.413 2c/a=20.0, a/t=0.428 2c/a=20.5, a/t=0.439 2c/a=21.3, a/t=0.454 2c/a=21.9, a/t=0.466 2c/a=22.6, a/t=0.481 2c/a=23.1, a/t=0.493 2c/a=ID circ, a/t=0.493 2c/a=ID circ, a/t=0.548 2c/a=ID circ, a/t=0.626 1.00 2c/a=ID circ, a/t=0.703 2c/a=ID circ, a/t=0.781 2c/a=ID circ, a/t=0.858 2c/a=ID circ, a/t=0.936 2c/a=ID circ, a/t=1.000 0.80 Selected growth steps shown Crack Depth (in) 0.60 PRELIMINARY 0.40 0.20 0.00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Circumferential Distance Along ID (in) 18 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Profile Comparison vs. Draft Phase 1 Result 1.20 Original Model Final Shape Current Model Final Shape 1.00 0.80 Crack Depth (in) 0.60 PRELIMINARY 0.40 0.20 0.00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Circumferential Distance Along ID (in) 19 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 9: Crack Depth and Area Development 1.0 a/t - Full Moment 0.9 a/t - Half Moment 0.8 Fraction Cracked - Full Moment 0.7 0.6 0.5 0.4 0.3 0.2 0.1 PRELIMINARY 0.0 0 1 2 3 4 5 6 7 8 time (yr) 20 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 11: SIF Along Crack Front 40,000 2c/a=20.9, a/t=0.260 2c/a=18.9, a/t=0.310 2c/a=18.4, a/t=0.342 2c/a=18.5, a/t=0.375 2c/a=19.0, a/t=0.395 2c/a=19.5, a/t=0.413 2c/a=20.0, a/t=0.428 2c/a=20.5, a/t=0.439 2c/a=21.3, a/t=0.454 2c/a=21.9, a/t=0.466 2c/a=22.6, a/t=0.481 2c/a=23.1, a/t=0.493 35,000 2c/a=ID circ, a/t=0.493 2c/a=ID circ, a/t=0.548 2c/a=ID circ, a/t=0.626 2c/a=ID circ, a/t=0.703 2c/a=ID circ, a/t=0.781 2c/a=ID circ, a/t=0.858 2c/a=ID circ, a/t=0.936 FEA Stress Intensity Factor, K (psi-in0.5) 30,000 Selected growth steps shown 25,000 PRELIMINARY 20,000 15,000 10,000 5,000 0
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Relative Distance Along Crack Front from Deepest Point to Surface Point (--)
21 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 12: SIF at Deepest and Surface Points vs. Depth 40,000 35,000 PRELIMINARY Crack-Tip Stress Intensity Factor, K (psi-in0.5) 30,000 25,000 20,000 15,000 10,000 K at Deepest Point 5,000 K at Surface Point K at Joined Edge 0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Maximum Crack Depth, a/t 22 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Figure 14: Crack Stability - Supportable Moment Supportable 3,000 Entire Crack in Tension Crack Takes Compression moment based 2,500 Crack Does Not Take Compression Applied Moment on standard thin-wall NSC Max Supportable Moment (in-kips) 2,000 model for 1,500 arbitrary circumferential 1,000 crack profile PRELIMINARY (Rahman and 500 Wilkowski, 0 1998) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 a/t 23 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Refined Phase I Calc Results Summary Through-wall flaw reached after approximately 7.5 years
- Increase in growth time due to refined time step and other refinements Net section collapse moment for final flaw shape is 1300 in-kips vs. 275 in-kips load (4.7x greater)
- Based on conservative case in which crack face does not take compression 24 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Comments on Crack Growth Calculation Comment #3. A significant result from these analyses was that the surface crack grew to 360 degrees before becoming through-wall. This effect was driven by the higher residual stresses at the inside diameter (ID) surface. In addition, the shape of the final defect at the location of maximum stress was highly driven by the magnitude of the bending stress relative to the ID welding residual stress. For similar residual stresses with lower bending moments, a critical 360-degree surface crack is likely to occur. Industry needs to address this issue in the analysis matrix for Phase II.
Response. As discussed in the draft Phase I calculation note, the growth to a 360° degree surface flaw results from the somewhat higher stress intensity factors along the surface associated with the crack shape in the ID surface neighborhood, compared to the results for a semi-elliptical flaw shape assumption. As has been discussed since the beginning of the project, the magnitude of the bending stress is expected to be a critical modeling parameter. Phase II was planned to include investigation of the effect of bending moment load based on the full range of piping moment loads collected for the group of 51 subject welds. Contrary to the statement regarding the likelihood of critical 360° surface cracks, recent work indicates that the surface crack is likely to arrest or greatly slow in growth without reaching critical crack size given lower bending moments and similar residual stresses (see following slides).
25 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Zero Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw Assumed axisymmetric stress profile at right 60 PRELIMINARY Endcap pressure based EndCap Press + DW + T + WRS 50 on ID at DM weld 40 Axial Stress with Residual Stress (ksi)
Dead weight axial force 30 included 20 10 Normal thermal axial force 0 included -10 WRS profile of Phase 1 -20 calculation also assumed -30 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Normalized Distance from ID Surface, x/t 26 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Zero Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw SIF per WRC Bulletin 50 solution for fully axisymmetric stress field 40 EndCap Press + CrackFaceP + DW + T + WRS Stress Intensity Factor with Residual Stress (ksi-in0.5)
(cubic dependence on 30 radial coordinate) and 20 360° uniform depth 10 circumferential surface 0 crack -10 WRC Bulletin includes -20 PRELIMINARY influence coefficients for case of Ri/t = 2, so no
-30 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Normalized Crack Depth, a/t extrapolation needed Crack face pressure applied via superposition 27 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Zero Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw Crack depth vs. time 1.0 based on integration of 0.9 PRELIMINARY MRP-115 CGR equation at 0.8 650°F Normalized Crack Depth from ID Surface, a/t EndCap Press + CrackFaceP + DW + T + WRS 0.7 Crack arrest predicted at 0.6 depth of about a/t = 0.35 0.5 Conclusion is that without 0.4 piping moment load, 0.3 0.2 assumed WRS profile 0.1 results in arrested (and 0.0 stable) part-depth crack for 0 2 4 6 8 10 Time (years) 12 14 16 18 20 the relief nozzle case investigated, regardless of initial crack aspect ratio 28 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Axisymmetric Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw Assumed axisymmetric 60 stress profile at right 50 PRELIMINARY EndCap Press + DW + T + WRS Axisymmetric linear stress 40 Axial Stress with Residual Stress (ksi) profile Mr/I added to previous 30 zero moment case 20 M taken as half base case 10 moment of 275 in-kips 0 This hypothetical -10 axisymmetric case bounds -20 capability of moment to drive -30 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 crack through-wall for Normalized Distance from ID Surface, x/t assumed WRS profile 29 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Axisymmetric Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw Same SIF solution 50 procedure as before using 40 EndCap Press + CrackFaceP + DW + T + WRS WRC Bulletin Stress Intensity Factor with Residual Stress (ksi-in0.5) 30 Crack face pressure 20 applied via superposition 10 0
-10 PRELIMINARY
-20
-30 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Normalized Crack Depth, a/t 30 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Axisymmetric Moment Axisymmetric Results for WC Relief Nozzle with 360° Flaw Crack depth vs. time 1.0 based on integration of PRELIMINARY 0.9 MRP-115 CGR equation at 0.8 Normalized Crack Depth from ID Surface, a/t EndCap Press + CrackFaceP + DW + T + WRS 650°F 0.7 0.6 Crack arrest predicted at 0.5 depth of about a/t = 0.45 0.4 Conclusion is that even 0.3 with half base case 0.2 moment of 275 in-kips, 0.1 assumed WRS profile 0.0 0 10 20 30 40 50 60 results in arrested (and Time (years) stable) part-depth crack for the relief nozzle case investigated, regardless of initial crack aspect ratio 31 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Reduced Moment FEA Results for WC Relief Nozzle with 21:1 Flaw Growth progression in flat plane for case of half previously assumed piping moment 1.20 2c/a=20.9, a/t=0.260 2c/a=19.8, a/t=0.303 2c/a=20.0, a/t=0.326 2c/a=20.7, a/t=0.342 2c/a=21.5, a/t=0.354 2c/a=22.5, a/t=0.363 2c/a=23.5, a/t=0.370 2c/a=24.6, a/t=0.376 2c/a=25.7, a/t=0.381 2c/a=26.8, a/t=0.385 2c/a=27.9, a/t=0.389 2c/a=29.1, a/t=0.392 2c/a=ID circ, a/t=0.392 2c/a=ID circ, a/t=0.399 2c/a=ID circ, a/t=0.426 1.00 Selected growth steps shown 0.80 Crack Depth (in)
PRELIMINARY 0.60 0.40 0.20 0.00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Circumferential Distance Along ID (in) 32 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Reduced Moment FEA Results for WC Relief Nozzle with 21:1 Flaw Crack depth development for case of half previously assumed piping moment 1.0 0.9 Full Moment Half Moment 0.8 0.7 0.6 a/t 0.5 0.4 0.3 0.2 PRELIMINARY 0.1 0.0 0 1 2 3 4 5 6 7 8 time (yr) 33 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Reduced Moment FEA Results for WC Relief Nozzle with 21:1 Flaw SIF along crack front for case of half previously assumed piping moment 40,000 2c/a=20.9, a/t=0.260 2c/a=19.8, a/t=0.303 2c/a=20.0, a/t=0.326 2c/a=20.7, a/t=0.342 2c/a=21.5, a/t=0.354 2c/a=22.5, a/t=0.363 2c/a=23.5, a/t=0.370 2c/a=24.6, a/t=0.376 35,000 2c/a=25.7, a/t=0.381 2c/a=26.8, a/t=0.385 2c/a=27.9, a/t=0.389 2c/a=29.1, a/t=0.392 2c/a=ID circ, a/t=0.392 2c/a=ID circ, a/t=0.399 2c/a=ID circ, a/t=0.426 FEA Stress Intensity Factor, K (psi-in0.5) 30,000 Selected growth steps shown 25,000 PRELIMINARY 20,000 15,000 10,000 5,000 0
1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Relative Distance Along Crack Front from Surface Point to Deepest Point (--)
34 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Reduced Moment FEA Results for WC Relief Nozzle with 21:1 Flaw SIF at deepest and surface points vs. depth for case of half previously assumed piping moment 40,000 35,000 PRELIMINARY Crack-Tip Stress Intensity Factor, K (psi-in0.5) 30,000 25,000 20,000 15,000 10,000 K at Deepest Point 5,000 K at Surface Point K at Joined Edge 0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Maximum Crack Depth, a/t 35 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Growth with Full Moment FEA Results for WC Relief Nozzle with 360° Flaw Initial and final flaw shape comparison for partial-arc initial flaw vs. 360° initial flaw 1.20 Start w/ PD 26% deep @ 21:1 Start w/ ID 360 @ 10% deep PD Initial Flaw Shape ID Circ Initial Flaw Shape 1.00 PRELIMINARY 0.80 Crack Depth (in) 0.60 0.40 0.20 0.00 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Circumferential Distance Along ID (in) 36 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
New FEA Crack Growth Cases Conclusions Smooth crack-tip SIF profiles result from greater mesh refinement at surface and smaller time step increment
- Starting from natural flaw shape does not improve SIF profiles Greater time step refinement (with other minor changes) yields time to through-wall of about 7.5 years Reduced moment leads to flaw arrest for assumed through-wall stress distribution High inside surface stresses lead to no significant difference in crack profile at through-wall penetration for partial-arc and 360° circumferential starting flaws
- 360° initial flaw @ 10% depth takes 8.4 years to reach same final flaw shape 37 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Comments on Critical Crack Size Calculation Comment #4. The last comment relates to the calculation of critical crack sizes which affect the calculation for the time to rupture. In the Phase I results, industry used a limit-load analysis with the weld metal flow stress to estimate the critical through-wall crack size; then industry used that cross-sectional cracked area to draw conclusions about the stability of the leaking surface crack.
In addition, industry did not evaluate the displacement-controlled stresses in this stability calculation, arguing that these stresses would be relieved by the plasticity and change in compliance due to the large crack. From reviewing past full-scale pipe testing results, it is the NRC staffs view that in conducting critical crack size analyses, industry must address the following concerns.
- Comment #4a. The location of the crack in a dissimilar weld can change the fracture response. If the crack is close to the safe-end then the lower strength of the stainless steel safe-end should be used. If the crack is in the center of the weld or closer to the ferritic nozzle side, the effective flow stress would be slightly higher than using the safe-end strength but much lower than using the weld metal strength properties. Hence, if the location of the crack in the weld is not known, then the conservative assumption is to use the lower safe-end strength properties. This fact is supported by both analyses and experiments.
38 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Comments on Critical Crack Size Calculation (contd)
- Comment #4b. Elastic-plastic fracture mechanics should be considered since in the NRC analyses, this condition controlled for some crack geometries. For an idealized circumferential through-wall crack as used in industrys failure analysis, the NRC staffs detailed finite element elastic-plastic analyses and pipe tests showed that failure stress would be below that predicted by limit-load analyses even when using the stainless-steel base-metal strength properties in the limit load analysis. For a circumferential surface flaw, the experiments and analyses suggest that limit-load using the lower strength properties would be appropriate. Finally, for a complex or compound crack, i.e., a long surface crack that penetrates the wall thickness for a short length, full-scale pipe tests have shown that the failure stress would be significantly below limit load. This crack shape is similar to the flaw found in the Duane Arnold safe end. The results also indicate that secondary stresses can lead to rapid severance of pipes containing complex cracks. Consequently, there can be significant non-conservatism in the industrys fracture analysis.
39 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Comments on Critical Crack Size Calculation (contd)
- Comment #4c. For large cracks, especially surface and complex cracks, the plasticity is localized to the area surrounding the crack, and therefore the secondary loads will not be relieved by a change in compliance. If the crack is large enough so that the rest of the pipe system remains elastic, then these secondary stresses will act as a primary stress. If the failure stresses are above yield of the uncracked pipe, there will be a gradual reduction of the importance of secondary stresses, but this is material and pipe-system geometry dependant.
This condition may begin to relieve some of these loads, but total relief will not occur until there is large scale plasticity in the uncracked pipe loop. This secondary stress effect on fracture response is consistent with the ASME Section III design rules that offer a warning about Local Overstrain due to a weakened pipe cross section. There are full-scale pipe system tests with different amounts of thermal expansion stress that illustrate this fracture behavior in NUREG reports and technical papers.
40 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Industry Response to Comment #4 Pete Riccardella of SI to present main response to Comment #4 Additional response material on next two slides
- Ductile tearing of thin surface ligaments
- Nominal stress in adjacent piping 41 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
April 4, 2007, NRC Letter Ductile Tearing of Thin Surface Ligaments Section 2.2.1 and Figure 4 of the draft EMC2 technical basis document for critical crack size recommend that a factor be applied for deep surface cracks There is an important distinction between a leakage failure (rupture of local ligament between crack tip and OD) and a break failure. All surface cracks will be predicted to have a leakage "failure" as they approach 100% through-wall according to the correction factor approach in Figure 4 of the EMC2 document.
If the through-wall crack created is stable, then in fact leakage and not a LOCA will result. We must check for thin surface ligaments at the ends of the through-wall section of the final complex crack.
A second order question is whether any surface ligament tearing during the previous crack growth changes the crack growth pattern significantly versus growth by SCC only. Under the conditions that could produce local ligament ductile tearing, the predicted SCC growth rate will be high, R. Kurihara, S. Ueda, and D. Sturm, Estimation of the effectively simulating the effect of the surface Ductile Unstable Fracture of Pipe with a Circumferential ligament tearing. Surface Crack Subjected to Bending, Nuclear Engineering and Design, Vol. 106, pp. 265-273, 1988.
42 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
43 This plots shows nominal stress in the attached piping assuming The results may be relevant the same pressure, axial force,
- some safety/relief and spray and effective moment Meff as regarding the role of secondary reported for the nozzles nozzle cases The stress is shown relative to the Code yield strength based stress in the crack stability on preliminary piping material
- all surge nozzle cases assumptions calculations These results show yield level stresses in (Pm +Pb )/y 0.0 0.5 1.0 1.5 2.0 2.5 0.0 01 A - Re (7.75x5.17) 0 0.7 5
02 A - SA (7.75x5.17) 1.5 0
03 A - SB (7.75x5.17) 2.2 5
3.0 04 A - SC (7.75x5.17) 0 3.7 5
05 E - Re (7.75x5.17) 4.5 0
5.2 06 E - SA (7.75x5.17) 5 6.0 Project Review Meeting: Advanced FEA Crack Growth Evaluations 0
07 E - SB (7.75x5.17) 6.7 5
P+DW+T 08 E - SC (7.75x5.17) 7.5 0
8.2 09 H - Re (7.75x5.17) 5 9.0 0
10 H - SA (7.75x5.17) 9.7 5
10 11 H - SB (7.75x5.17) .5 0
11 P+DW+T+Tstrat
.2 12 H - SC (7.75x5.17) 5 12
.0 0
WC1 J - Re (7.75x5.17) 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 0
14
.2 April 4, 2007, NRC Letter WC2 J - SA (7.75x5.17) 5 15
.0 0
Nominal Stress in Adjacent Piping WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 Notes 20
.2 5
16 F - SC (8x5.19) 21
.0 where I = (Ro - Ri )/4 0
21 17 B - Re (7.75x5.62) .7 5
22
.5 0
18 B - SA (7.75x5.62) 23
.2 4 5 24 19 B - SB (7.75x5.62) .0 0
- 1. Pm = PDo/4t + Faxial/Ametal 24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
21 G - Re (7.75x5.62) 4 26
.2 5
- 3. y = 18.5 ksi for S&R and spray piping based on Code 27 22 G - SA (7.75x5.62) .0 0
27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
where Faxial = DW+T or DW+T+Tstrat axial force 24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31 min YS for A376 TP316 at 650°F
.5 0
2 2 32 27 C - SB (7.75x5.62) .2 5
33
.0 28 C - SC (7.75x5.62) 0 33
.7 5
and Ametal = (Do - Di )/4 29 D - Re (8x4.937) 34
.5 0
35 30 D - SA (8x4.937) .2 5
36
.0 0
31 D - SB (8x4.937) 36
.7
- 4. y = 18.0 ksi for surge line piping based on Code min 5
37 32 D - SC (8x4.937) .5 0
38
.2 5
May 8, 2007, North Bethesda, Maryland 33 I - Re (8x4.937)
- 2. Pb = MeffDo/2I 39
.0 0
34 I - SA (8x4.937) 39
.7 5
40 35 I - SB (8x4.937) .5 0
41
.2 5
36 A - Sp (5.81x4.01)
YS for A376 TP304 at 650°F 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 40 C - Sp (5.81x4.25) 0 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
43 I - Sp (5.188x3.25) 50
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844) 55
.5 0
48 G - Su (15x11.844) 56
.2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59 51 I - Su (13.063x10.125) .2 5
60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
Status of NRC Confirmatory Research To be presented by NRC 44 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Items Item 1. Plant Specific Geometries Item 2. Plant Specific Loads Item 3. Proposed Weld Residual Stresses
- Cracks growing in an axisymmetric WRS field
- Cracks growing in an axisymmetric + repair WRS field Item 4. Crack Growth Rate Equation Item 5. Multiple Crack Growth Calculations Other Items
- Initial flaw geometry
- Redistribution of load given high WRS at ID surface
- Crack inserted directly into the 3-dimensional DEI WRS FEA model 45 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry for Subject Plants Summary There are a total of 51 pressurizer DM welds of concern in the group of nine plants:
- 35 safety and relief (S&R) nozzles (1 plant has only three S&R nozzles)
- 8 surge nozzles (+1 already overlayed)
- 8 spray nozzles (+1 examined by PDI process in 2005)
Using design drawings, basic weld dimensions have been tabulated for the 51 subject welds:
- Weld thickness
- For welds with taper from LAS nozzle to safe end, thickness is based on average of design diameters at toe on nozzle and at toe on safe end
- Liner or sleeve thickness not included in weld thickness for cases in which liner or sleeve is in direct contact with DM weld
- Radius to thickness ratio (Ri/t) based on design inside diameter at weld and weld thickness per previous bullet
- Approximate weld separation axial distance between root of DM weld and root of SS weld to piping 46 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry for Subject Plants Geometry Cases A review of design drawings for the nine plants indicates the following nozzle geometry cases:
- S&R nozzles
- Types 1a and 1b: W design without liner, connected to 6 pipe
- Types 2a and 2b: W design with liner directly covering DM weld, connected to 6 pipe
- Type 3: CE design (no liner), connected to 6 pipe
- Spray nozzles
- Type 4: W design with liner (does not extend to most of DM weld), connected to 4 pipe
- Type 5: W design with liner directly covering DM weld, connected to 4 pipe
- Type 6: W design without liner, connected to 6 pipe
- Surge nozzles
- Type 8: W design (sleeve directly covers fill-in weld under nozzle-to-safe-end weld),
connected to 14 pipe
- Type 9: CE design (sleeve not extending to DM weld), connected to 12 pipe 47 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry and Repair History PRELIMINARY Summary Table Relief Safety A DM Weld Ri/t DM Weld Ri/t Butter Weld Butter Weld Piping NPS Piping NPS DM Weld t Weld Sep. OD Weld DM Weld t Weld Sep. OD Weld Design # Design #
ID Weld ID Weld Liner? Liner?
Plant Code (in.) (in.) Repairs Repairs Repairs (in.) (in.) Repairs Repairs Repairs Plant A 1a 6" N 1.29 2.0 2.2 NR NR NR 1a 6" N 1.29 2.0 2.2 NR NR R4 Plant E 1a 6" N 1.29 2.0 2.2 NR NR R 1a 6" N 1.29 2.0 2.2 NR NR NR Plant H 1a 6" N 1.29 2.0 2.2 NR NR NR 1a 6" N 1.29 2.0 2.2 NR R R Plant B 2a 6" Y 1.07 2.6 2.6 NR NR R1 2a 6" Y 1.07 2.6 2.6 NR NR NR Plant G 2a 6" Y 1.07 2.6 2.6 NR NR NR 2a 6" Y 1.07 2.6 2.6 NR NR NR Plant C 2b 6" Y 1.07 2.6 2.3 NR NR NR 2b 6" Y 1.07 2.6 2.3 R Plant F 1b 6" N 1.41 1.8 3.3 NR NR NR 1b 6" N 1.41 1.8 3.3 R Plant D 3 6" N 1.41 1.8 6.8 NR NR NR 3 6" N 1.41 1.8 6.8 R NR NR Plant I 3 6" N 1.41 1.8 6.8 N/A N/A N/A 3 6" N 1.41 1.8 6.8 N/A N/A N/A Plant J 1a 6" N 1.29 2.0 2.2 Rx5 R1 R1 1a 6" N 1.29 2.0 2.2 R R2 NR Notes:
- 1. For Designs #2a, #2b, and #5, liner directly covers DM weld.
- 2. For Design #4, liner does not extend to most of DM weld.
- 6. NR = No weld repairs reported
- 7. Rn = Repairs reported (n indicates number of defect or repaired areas if reported; "x" indicates repeat weld repair operations)
- 8. N/A = Results for fabrication records review not available
- 9. Weld repair entries for Plants C and F are preliminary.
- 10. All pressurizer nozzle DM welds in Plant H are reported to be Alloy 82, not Alloy 82/182.
48 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry and Repair History PRELIMINARY Summary Table (contd)
Safety B Safety C DM Weld Ri/t DM Weld Ri/t Butter Weld Butter Weld Piping NPS Piping NPS DM Weld t Weld Sep. OD Weld DM Weld t Weld Sep. OD Weld Design # Design #
ID Weld ID Weld Liner? Liner?
Plant Code (in.) (in.) Repairs Repairs Repairs (in.) (in.) Repairs Repairs Repairs Plant A 1a 6" N 1.29 2.0 2.2 NR R1 NR 1a 6" N 1.29 2.0 2.2 NR NR NR Plant E 1a 6" N 1.29 2.0 2.2 NR NR NR 1a 6" N 1.29 2.0 2.2 NR R NR Plant H 1a 6" N 1.29 2.0 2.2 NR NR NR 1a 6" N 1.29 2.0 2.2 NR NR NR Plant B 2a 6" Y 1.07 2.6 2.6 NR NR NR 2a 6" Y 1.07 2.6 2.6 NR NR NR Plant G 2a 6" Y 1.07 2.6 2.6 NR NR NR 2a 6" Y 1.07 2.6 2.6 NR NR NR Plant C 2b 6" Y 1.07 2.6 2.3 R 2b 6" Y 1.07 2.6 2.3 R Plant F 1b 6" N 1.41 1.8 3.3 NR NR NR 1b 6" N 1.41 1.8 3.3 NR NR NR Plant D 3 6" N 1.41 1.8 6.8 NR NR NR 3 6" N 1.41 1.8 6.8 NR NR NR Plant I 3 6" N 1.41 1.8 6.8 N/A N/A N/A No Safety C Plant J 1a 6" N 1.29 2.0 2.2 NR R6x2 NR 1a 6" N 1.29 2.0 2.2 NR NR NR Notes:
- 1. For Designs #2a, #2b, and #5, liner directly covers DM weld.
- 2. For Design #4, liner does not extend to most of DM weld.
- 6. NR = No weld repairs reported
- 7. Rn = Repairs reported (n indicates number of defect or repaired areas if reported; "x" indicates repeat weld repair operations)
- 8. N/A = Results for fabrication records review not available
- 9. Weld repair entries for Plants C and F are preliminary.
- 10. All pressurizer nozzle DM welds in Plant H are reported to be Alloy 82, not Alloy 82/182.
49 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry and Repair History PRELIMINARY Summary Table (contd)
Spray (all have thermal sleeve) Surge (all have thermal sleeve)
DM Weld Ri/t DM Weld Ri/t Butter Weld Butter Weld Piping NPS Piping NPS DM Weld t Weld Sep. OD Weld DM Weld t Weld Sep. OD Weld Design # Design #
ID Weld ID Weld Liner? Liner?
Plant Code (in.) (in.) Repairs Repairs Repairs (in.) (in.) Repairs Repairs Repairs Plant A 4 4" Y 0.90 2.2 ~2.3 NR NR NR 8 14" N 1.58 3.8 3.4 NR R5 R3 Plant E 4 4" Y 0.90 2.2 ~2.3 R NR R 8 14" N 1.58 3.8 3.4 NR R3 NR Plant H Already PDI examined 8 14" N 1.58 3.8 3.4 NR NR NR Plant B 5 4" Y 0.78 2.7 2.2 NR NR NR 8 14" N 1.58 3.8 3.4 R1 R1x2 R2 Plant G 5 4" Y 0.78 2.7 2.2 NR NR NR 8 14" N 1.58 3.8 3.4 NR NR NR Plant C 5 4" Y 0.78 2.7 ~2.2 R 8 14" N 1.56 3.8 3.5 NR NR NR Plant F 6 6" N 1.15 2.5 3.6 NR NR NR Already structural overlayed Plant D 7 4" N 1.06 1.4 3.3 NR NR NR 9 12" N 1.47 3.4 3.0 NR NR NR Plant I 7 4" N 1.06 1.4 3.3 N/A N/A N/A 9 12" N 1.47 3.4 3.0 N/A N/A N/A Plant J 4 4" Y 0.90 2.2 ~2.3 R NR NR 8 14" N 1.58 3.8 3.4 R2 R1 NR Notes:
- 1. For Designs #2a, #2b, and #5, liner directly covers DM weld.
- 2. For Design #4, liner does not extend to most of DM weld.
- 6. NR = No weld repairs reported
- 7. Rn = Repairs reported (n indicates number of defect or repaired areas if reported; "x" indicates repeat weld repair operations)
- 8. N/A = Results for fabrication records review not available
- 9. Weld repair entries for Plants C and F are preliminary.
- 10. All pressurizer nozzle DM welds in Plant H are reported to be Alloy 82, not Alloy 82/182.
50 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
51 0 2 4 6 8 10 12 14 0.
01 A - Re (7.75x5.17) 00 0.
75 02 A - SA (7.75x5.17) 1.
50 03 A - SB (7.75x5.17) 2.
25 3.
00 04 A - SC (7.75x5.17) 3.
75 05 E - Re (7.75x5.17) 4.
50 5.
06 E - SA (7.75x5.17) 25 6.
00 07 E - SB (7.75x5.17) 6.
ID (in) 75 08 E - SC (7.75x5.17) OD (in) 7.
50 8.
t (in) 25 09 H - Re (7.75x5.17) 9.
00 10 H - SA (7.75x5.17)
ID/t 9.
75 10 11 H - SB (7.75x5.17) .5 0
11
.2 12 H - SC (7.75x5.17) 5 12
.0 0
WC1 J - Re (7.75x5.17) 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 0
14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21
.7 17 B - Re (7.75x5.62) 5 Basic Weld Dimensions 22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
21 G - Re (7.75x5.62) 26
.2 5
27 22 G - SA (7.75x5.62) .0 0
Project Review Meeting: Advanced FEA Crack Growth Evaluations 27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32 27 C - SB (7.75x5.62) .2 5
33
.0 0
28 C - SC (7.75x5.62) 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
37 32 D - SC (8x5.19) .5 0
38
.2 33 I - Re (8x5.188) 5 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40 35 I - SB (8x5.188) .5 0
41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 0
40 C - Sp (5.81x4.25) 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
43 I - Sp (5.188x3.25) 50 Nozzle Geometry for Subject Plants May 8, 2007, North Bethesda, Maryland
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844) 55
.5 0
56 48 G - Su (15x11.844) .2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59 51 I - Su (13.063x10.125) .2 5
60 0 50 .0 100 150 200 250 300 350 400 0
Nozzle Geometry for Subject Plants As-Built Dimensional Information Available as-built dimensions are being collected for the subject welds This information is being used to investigate as-built versus design dimensions:
- DM weld OD (average between toe on nozzle and toe on safe end)
- DM weld thickness
- Separation distance between DM and SS welds Sensitivity cases for the crack growth and crack stability calculations are planned to check sensitivity to as-built dimensions 52 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
As-Built Dimensional Information Review of Plant H As-Built Dimensions Following as-built dimensions are preliminary Safety/Relief
- LAS nozzle end thickness of 1.16 - 1.37 vs. design of 1.42 (including cladding)
- Butter thickness of 0.80 vs. design of 0.81 Spray
- LAS nozzle end thickness of 0.87 - 0.92 vs. design of 1.00 (including liner) and 0.88 (without liner)
- Safe end OD at DM weld of ~5.65 vs. design of 5.62 Surge
- LAS nozzle end thickness of 1.40 - 1.60 vs. design of 1.51 (including cladding)
- Butter thickness of 0.30 vs. design of 0.81 In general, as-built thickness of butter buildup on LAS nozzle end can vary significantly 53 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
As-Built Dimensional Information Review of Plant C As-Built Dimensions Following as-built dimensions are preliminary
- There is uncertainty in the weld separation figures because only axial length of various materials on OD is provided Relief
- Separation distance of ~2.18 vs. design of 2.32
- DM weld circumference of 24.5 vs. design of 24.3 (based on average OD of 7.75)
- DM weld thickness of 1.14 vs. design of 1.07 (without liner)
Safety A
- Separation distance of ~2.2 vs. design of 2.32 Safety B
- Separation distance of ~1.85 vs. design of 2.32
- DM weld thickness of 1.08 vs. design of 1.07 (without liner)
Safety C
- Separation distance of ~2.3 vs. design of 2.32
- DM weld thickness of 1.14 vs. design of 1.07 (without liner) 54 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
As-Built Dimensional Information Review of Plant C As-Built Dimensions (contd)
Spray
- Separation distance of ~3.25 vs. design of 2.2 Surge
- Separation distance of ~3.73 vs. design of 3.46
- Average DM weld thickness of 1.501 vs. design of 1.563
- DM weld circumference of 46.875 vs. design of 47.12 (based on OD of 15.00) 55 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Plant-Specific Piping Loads Approach Design pipe loads have now been collected for each of the 51 subject welds Differences in pipe axial force and moment loads have multiple effects on the relative crack growth rate in the radial and circumferential directions, as well as an effect on critical crack size Therefore, cover full range of piping loads for 51 subject welds:
- All plants 2235 psig pressure
- Range of axial membrane stress loading, Pm
- Range of bending stress loading, Pb
- Range of ratio of bending to total stress loading, Pb/(Pm+Pb)
- Crack growth loads include dead weight and normal thermal pipe expansion loads (and normal thermal stratification loads in case of surge nozzles)
- Length of thermal strain applied to simulate WRS will be varied 56 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
57 Faxial (kips) 0 10 20 30 40 0.
01 A - Re (7.75x5.17) 00 0.
75 02 A - SA (7.75x5.17) 1.
50 03 A - SB (7.75x5.17) 2.
25 3.
00 04 A - SC (7.75x5.17) 3.
75 05 E - Re (7.75x5.17) 4.
50 5.
06 E - SA (7.75x5.17) 25 6.
00 07 E - SB (7.75x5.17) 6.
75 08 E - SC (7.75x5.17) 7.
50 DW 8.
25 09 H - Re (7.75x5.17) 9.
00 10 H - SA (7.75x5.17) DW+SSE 9.
75 10 11 H - SB (7.75x5.17) .5 0
DW+T 11
.2 12 H - SC (7.75x5.17) 5 12
.0 DW+T+SSE 0 WC1 J - Re (7.75x5.17) 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 DW+T+Strat 0 14
.2 5
WC2 J - SA (7.75x5.17) 15 DW+T+Strat+SSE .0 0
WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21 17 B - Re (7.75x5.62) .7 5
22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
21 G - Re (7.75x5.62) 26
.2 5
Project Review Meeting: Advanced FEA Crack Growth Evaluations 27 22 G - SA (7.75x5.62) .0 0
27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32 27 C - SB (7.75x5.62) .2 5
33
.0 28 C - SC (7.75x5.62) 0 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
37 Plant-Specific Piping Loads 32 D - SC (8x5.19) .5 0
38
.2 33 I - Re (8x5.188) 5 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40 35 I - SB (8x5.188) .5 0
41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 40 C - Sp (5.81x4.25) 0 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
May 8, 2007, North Bethesda, Maryland 43 I - Sp (5.188x3.25) 50
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844) 55
.5 0
48 G - Su (15x11.844) 56
.2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
Nominal Axial Piping Loads (Not Including Endcap Pressure Load) 59 51 I - Su (13.063x10.125) .2 5
60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
58 Meff (in-kips) 0 1000 2000 3000 4000 5000 6000 0.
01 A - Re (7.75x5.17) 00 0.
75 02 A - SA (7.75x5.17) 1.
50 03 A - SB (7.75x5.17) 2.
25 3.
00 04 A - SC (7.75x5.17) 3.
75 05 E - Re (7.75x5.17) 4.
50 5.
06 E - SA (7.75x5.17) 25 P+DW 6.
00 07 E - SB (7.75x5.17) 6.
75 08 E - SC (7.75x5.17) P+DW+SSE 7.
50 8.
25 09 H - Re (7.75x5.17) 9.
P+DW+T 00 10 H - SA (7.75x5.17) 9.
75 10 11 H - SB (7.75x5.17) P+DW+T+SSE .5 0
11
.2 12 H - SC (7.75x5.17) 5 12
.0 0
WC1 J - Re (7.75x5.17) P+DW+T+Strat 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 0
P+DW+T+Strat+SSE 14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21
.7 17 B - Re (7.75x5.62) 5 22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
Project Review Meeting: Advanced FEA Crack Growth Evaluations 21 G - Re (7.75x5.62) 26
.2 5
27 22 G - SA (7.75x5.62) .0 0
27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32 27 C - SB (7.75x5.62) .2 5
33
.0 28 C - SC (7.75x5.62) 0 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35 30 D - SA (8x5.19) .2 5
36
.0 0
31 D - SB (8x5.19) 36
.7 5
Plant-Specific Piping Loads 37 32 D - SC (8x5.19) .5 0
38
.2 33 I - Re (8x5.188) 5 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40 35 I - SB (8x5.188) .5 0
41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 40 C - Sp (5.81x4.25) 0 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
May 8, 2007, North Bethesda, Maryland 43 I - Sp (5.188x3.25) 50
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844)
Nominal Effective Bending Moment Load (Full Scale) 55
.5 0
48 G - Su (15x11.844) 56
.2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59 51 I - Su (13.063x10.125) .2 5
60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
59 Meff (in-kips) 0 100 200 300 400 500 600 700 800 0.
01 A - Re (7.75x5.17) 00 0.
75 02 A - SA (7.75x5.17) 1.
50 03 A - SB (7.75x5.17) 2.
25 3.
00 04 A - SC (7.75x5.17) 3.
75 05 E - Re (7.75x5.17) 4.
50 5.
06 E - SA (7.75x5.17) 25 P+DW 6.
00 07 E - SB (7.75x5.17) 6.
75 08 E - SC (7.75x5.17) P+DW+SSE 7.
50 8.
25 09 H - Re (7.75x5.17)
P+DW+T 9.
00 10 H - SA (7.75x5.17) 9.
75 10 11 H - SB (7.75x5.17) P+DW+T+SSE .5 0
11
.2 12 H - SC (7.75x5.17) 5 12
.0 P+DW+T+Strat 0 WC1 J - Re (7.75x5.17) 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 P+DW+T+Strat+SSE 0 14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21 17 B - Re (7.75x5.62) .7 5
22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
21 G - Re (7.75x5.62)
Project Review Meeting: Advanced FEA Crack Growth Evaluations 26
.2 5
27 22 G - SA (7.75x5.62) .0 0
27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32 27 C - SB (7.75x5.62) .2 5
33
.0 28 C - SC (7.75x5.62) 0 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
Plant-Specific Piping Loads 37 32 D - SC (8x5.19) .5 0
38
.2 33 I - Re (8x5.188) 5 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40 35 I - SB (8x5.188) .5 0
41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 40 C - Sp (5.81x4.25) 0 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
May 8, 2007, North Bethesda, Maryland 43 I - Sp (5.188x3.25) 50
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844) 55
.5 0
56 48 G - Su (15x11.844) .2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58 Nominal Effective Bending Moment Load (Partial Scale)
.5 0
59 51 I - Su (13.063x10.125) .2 5
60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
60 Pm , Pb , Pm +Pb Stress Loading (ksi) 0 4 8 12 16 0.0 01 A - Re (7.75x5.17) 0 0.7 5
02 A - SA (7.75x5.17) 1.5 0
2.2 03 A - SB (7.75x5.17) 5 3.0 0
04 A - SC (7.75x5.17) 3.7 5
05 E - Re (7.75x5.17) 4.5 0
5.2 06 E - SA (7.75x5.17) 5 6.0 0
07 E - SB (7.75x5.17) Pm 6.7 5
08 E - SC (7.75x5.17) 7.5 0
Pm with SSE 8.2 09 H - Re (7.75x5.17) 5 9.0 Pb 0 10 H - SA (7.75x5.17) 9.7 5
10 11 H - SB (7.75x5.17) Pb with SSE .5 0
11
.2 5
12 H - SC (7.75x5.17) Pm+Pb 12
.0 0
WC1 J - Re (7.75x5.17) 12
.7 Pm+Pb with SSE 5 13
.5 WC1a J - Re/Sa (7.75x5.17) 0 14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
15 WC3 J - SB (7.75x5.17) .7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 0
15 F - SB (8x5.19) 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21
.7 17 B - Re (7.75x5.62) 5 22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 5
20 B - SC (7.75x5.62) 25
.5 0
21 G - Re (7.75x5.62) 26
.2 5
Project Review Meeting: Advanced FEA Crack Growth Evaluations 27
.0 22 G - SA (7.75x5.62) 0 ASME Code Nominal Stress Loading for Pressure and 27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
29 24 G - SC (7.75x5.62) .2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32
.2 27 C - SB (7.75x5.62) 5 33
.0 0
28 C - SC (7.75x5.62) 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
37 32 D - SC (8x5.19) .5 0
Plant-Specific Piping Loads 38
.2 5
33 I - Re (8x5.188) 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40
.5 35 I - SB (8x5.188) 0 41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
42 37 E - Sp (5.81x4.01) .7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45
.7 39 G - Sp (5.81x4.25) 5 46
.5 0
40 C - Sp (5.81x4.25) 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
43 I - Sp (5.188x3.25) 50 May 8, 2007, North Bethesda, Maryland
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 5
45 E - Su (15x11.844) 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54
.0 WC6 J - Su (15x11.844) 0 54
.7 5
47 B - Su (15x11.844) 55
.5 0
56 48 G - Su (15x11.844) .2 5
57
.0 0
Dead Weight Loading 49 C - Su (15x11.875) 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59
.2 51 I - Su (13.063x10.125) 5 60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
61 Pm , Pb , Pm +Pb Stress Loading (ksi) 0 5 10 15 20 0.0 01 A - Re (7.75x5.17) 0 0.7 5
02 A - SA (7.75x5.17) 1.5 0
2.2 03 A - SB (7.75x5.17) 5 3.0 0
04 A - SC (7.75x5.17) 3.7 5
05 E - Re (7.75x5.17) 4.5 0
5.2 06 E - SA (7.75x5.17) 5 6.0 0
07 E - SB (7.75x5.17) Pm 6.7 5
08 E - SC (7.75x5.17) 7.5 Pm with SSE 0 8.2 09 H - Re (7.75x5.17) 5 Pb 9.0 0
10 H - SA (7.75x5.17) 9.7 5
11 H - SB (7.75x5.17)
Pb with SSE 10
.5 0
11
.2 Pm+Pb 5 12 H - SC (7.75x5.17) 12
.0 0
WC1 J - Re (7.75x5.17) 12 Pm+Pb with SSE .7 5
13
.5 WC1a J - Re/Sa (7.75x5.17) 0 14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
15 WC3 J - SB (7.75x5.17) .7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 0
15 F - SB (8x5.19) 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21
.7 17 B - Re (7.75x5.62) 5 22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 5
20 B - SC (7.75x5.62) 25
.5 0
21 G - Re (7.75x5.62) 26
.2 5
Project Review Meeting: Advanced FEA Crack Growth Evaluations 27
.0 22 G - SA (7.75x5.62) 0 27
.7 5
23 G - SB (7.75x5.62) 28
.5 ASME Code Nominal Stress Loading for Pressure, Dead 0
29 24 G - SC (7.75x5.62) .2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 5
26 C - SA (7.75x5.62) 31
.5 0
32
.2 27 C - SB (7.75x5.62) 5 33
.0 0
28 C - SC (7.75x5.62) 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
37 32 D - SC (8x5.19) .5 0
Plant-Specific Piping Loads 38
.2 5
33 I - Re (8x5.188) 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40
.5 35 I - SB (8x5.188) 0 41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
42 37 E - Sp (5.81x4.01) .7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45
.7 39 G - Sp (5.81x4.25) 5 46
.5 0
40 C - Sp (5.81x4.25) 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
43 I - Sp (5.188x3.25) 50 May 8, 2007, North Bethesda, Maryland
.2 5
51 44 A - Su (15x11.844) .0 0
51
.7 5
45 E - Su (15x11.844) 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54
.0 WC6 J - Su (15x11.844) 0 54
.7 5
47 B - Su (15x11.844) 55
.5 0
56 48 G - Su (15x11.844) .2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59
.2 51 I - Su (13.063x10.125) 5 Weight, and Normal Thermal Loading 60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0
62 Pm , Pb , Pm +Pb Stress Loading (ksi) 0 5 10 15 20 25 30 35 40 0.
01 A - Re (7.75x5.17) 00 0.
75 02 A - SA (7.75x5.17) 1.
50 03 A - SB (7.75x5.17) 2.
25 3.
00 04 A - SC (7.75x5.17) 3.
75 05 E - Re (7.75x5.17) 4.
50 5.
06 E - SA (7.75x5.17) 25 Pm 6.
00 07 E - SB (7.75x5.17) 6.
75 08 E - SC (7.75x5.17) Pm with SSE 7.
50 8.
25 09 H - Re (7.75x5.17) Pb 9.
00 10 H - SA (7.75x5.17) Pb with SSE 9.
75 10 11 H - SB (7.75x5.17) .5 0
12 H - SC (7.75x5.17)
Pm+Pb 11
.2 5
12
.0 Pm+Pb with SSE 0 WC1 J - Re (7.75x5.17) 12
.7 5
13 WC1a J - Re/Sa (7.75x5.17) .5 0
14
.2 5
WC2 J - SA (7.75x5.17) 15
.0 0
WC3 J - SB (7.75x5.17) 15
.7 5
16
.5 WC4 J - SC (7.75x5.17) 0 17
.2 5
13 F - Re (8x5.19) 18
.0 0
18 14 F - SA (8x5.19) .7 5
19
.5 15 F - SB (8x5.19) 0 20
.2 5
16 F - SC (8x5.19) 21
.0 0
21
.7 17 B - Re (7.75x5.62) 5 22
.5 0
18 B - SA (7.75x5.62) 23
.2 5
24 19 B - SB (7.75x5.62) .0 0
24
.7 20 B - SC (7.75x5.62) 5 25
.5 0
21 G - Re (7.75x5.62) 26
.2 5
Project Review Meeting: Advanced FEA Crack Growth Evaluations 27 22 G - SA (7.75x5.62) .0 0
27
.7 5
23 G - SB (7.75x5.62) 28
.5 0
24 G - SC (7.75x5.62) 29
.2 5
30
.0 25 C - Re (7.75x5.62) 0 30
.7 ASME Nominal Stress Loading for Pressure, Dead Weight, 5
26 C - SA (7.75x5.62) 31
.5 0
32 27 C - SB (7.75x5.62) .2 5
33
.0 28 C - SC (7.75x5.62) 0 33
.7 5
29 D - Re (8x5.19) 34
.5 0
35
.2 30 D - SA (8x5.19) 5 36
.0 0
31 D - SB (8x5.19) 36
.7 5
37 32 D - SC (8x5.19) .5 0
Plant-Specific Piping Loads 38
.2 33 I - Re (8x5.188) 5 39
.0 0
34 I - SA (8x5.188) 39
.7 5
40 35 I - SB (8x5.188) .5 0
41
.2 5
36 A - Sp (5.81x4.01) 42
.0 0
37 E - Sp (5.81x4.01) 42
.7 5
43
.5 WC5 J - Sp (5.81x4.01) 0 44
.2 5
38 B - Sp (5.81x4.25) 45
.0 0
45 39 G - Sp (5.81x4.25) .7 5
46
.5 40 C - Sp (5.81x4.25) 0 47
.2 5
41 F - Sp (8x5.695) 48
.0 0
48
.7 42 D - Sp (5.188x3.062) 5 49
.5 0
43 I - Sp (5.188x3.25) 50
.2 5
May 8, 2007, North Bethesda, Maryland 51 44 A - Su (15x11.844) .0 0
51
.7 45 E - Su (15x11.844) 5 52
.5 0
46 H - Su (15x11.844) 53
.2 5
54 WC6 J - Su (15x11.844) .0 0
54
.7 5
47 B - Su (15x11.844) 55
.5 0
48 G - Su (15x11.844) 56
.2 5
57
.0 49 C - Su (15x11.875) 0 57
.7 5
50 D - Su (13.063x10.125) 58
.5 0
59 51 I - Su (13.063x10.125) .2 5
60 0 1 .0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 Normal Thermal, and Normal Thermal Stratification Loading
Plant-Specific Piping Loads Treatment of Loads in Crack Growth Modeling Each category of loading be treated as follows in the crack growth calculation:
- Deadweight: Axial force and bending moment applied to end of model
- Internal pressure: End cap axial force based on ID at weld, plus full crack face pressure applied directly to crack face for surface and through-wall cracks
- Normal pipe thermal expansion: Axial force and bending moment applied to end of model (no credit taken for relaxation of load with crack opening)
- Normal thermal stratification pipe bending moment (surge nozzle only): Added to normal thermal loads
- Thermal stratification pipe bending moment for plant transients (surge nozzle only): Not relevant for crack growth
- Welding residual stress: Multiple cases assumed as described separately below
- Local thermal stress due to differential thermal expansion (Q-stress): Considered as a sensitivity case in cracked WRS model
- Seismic loads: Not relevant for crack growth 63 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Plant-Specific Piping Loads Treatment of Loads in Crack Growth Modeling (contd)
For global moment loads, the following equation (NUREG/CR-6299) is being used to calculate an effective global bending moment:
2 3
M eff = M y2 + M z2 + T 2
The equation considers the effect of the applied torsion on the Von Mises effective stress This is a simplification as torsion would act as a Mode II and/or III loading on the crack 64 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Welding Residual Stress Summary of May 1 Meeting Fabrication Steps affecting WRS
- Last Pass Fill-In Weld (Surge)
- Fillet Welds (Safety/Relief)
- Buildup on Safe End ID Repairs
- Deep ID Repairs
- ID Repairs on Spray Nozzle?
65 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Welding Residual Stress Agenda of May 1 Meeting at DEI Offices Nozzle and weld geometry cases for subject welds Collected weld repair information for subject welds Application of WRS FEA models
- Previous FEA results by DEI (MRP-106)
- FEA work by Battelle and EMC2 (presentation by Dave Rudland, EMC2)
- Discussion of approach to new FEA for selected subject weld cases WRS data for piping butt welds in open literature Candidate WRS profiles
- Axisymmetric profiles
- Non-axisymmetric profiles Validation of WRS inputs Meeting wrap-up 66 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Tentative New FEA WRS Cases Planned at May 1 Meeting Effect of SS weld on stress in DM weld
- One axisymmetric case to be selected based on design and available as-built weld separation data
- Influence is expected to depend on x/t and Ri/t, where x is the weld separation distance Surge nozzle cases
- No repairs with fill-in weld
- 0.5 deep ID repair followed by fill-in weld
- CE nozzle case with no fill-in weld Spray nozzle cases
- Consider deferring until Plant C and F weld repair records are searched Safety/relief nozzle cases
- Model effect of 1/8 weld buildup on safe end ID (geometry based on WC)
- No repairs with liner fillet weld
- 3/4 deep ID repair followed by liner fillet weld
- Consider modeling short, deep repairs using 3D model 67 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Development of WRS Cases Approach Because of the uncertainty in the true residual stress field in each of the 51 subject welds, a matrix of sensitivity cases will be considered covering a wide range of WRS patterns Range of welding residual stress profiles
- Axisymmetric (self balance at every circumferential position)
- Non-axisymmetric (self balance over entire cross section)
- Weld fabrication and repair data compiled as input to selection of WRS profiles for analysis As previously planned, the following sources will be applied to develop the WRS cases considered:
- Weld fabrication and repair data from construction for the 51 subject welds
- Previous WRS calculations by DEI and others for PWR piping butt welds
- Limited number of DEI WRS FEA model runs for the specific geometry of some of the 51 subject welds considering the weld fabrication information
- WRS data in the open literature
- FEA simulations
- Stress measurements on mockups and removed components 68 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Development of WRS Cases Approach (contd)
Patterns of WRS variability will be considered in both the radial and circumferential directions For the cylindrical shell SIF model, the WRS will be simulated using an applied thermal input pattern, which may vary in the radial and circumferential directions
- Simulation of WRS using thermal strains is a standard technique
- The axial extent of the applied temperature load will be conservatively chosen based on the design length of the DM weld
- This length will be varied in sensitivity cases to check for the effect of residual stress relaxation For selected sensitivity cases of the optional SIF modeling, the 3-dimensional WRS field from the DEI intact WRS FEA model will be directly input to the cracked SIF model 69 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Welding Residual Stress Inputs Weld Fabrication and Repair Data Compiled for Wolf Creek Available data on initial weld fabrication and repair has also been compiled for the subject welds
- See next two slides Source: MRP 2007-003 Attachment 1 (White Paper).
70 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry and Repair History PRELIMINARY Weld Repair Summary Table
- Defect Defect/Repair Defect/Repair Defect/Repair Defect/Repair Defect/Repair Defect/Repair ID/OD Alloy PWHT or Area #1 Area #2 Area #3 Area #4 Area #5 Area #6 Table Plant Nozzle Nozzle Design Buttering (% 82 or after Repair Length Depth Length Depth Length Depth Length Depth Length Depth Length Depth Line Code Type Count # or Weld circ.) 182 Repair? Areas (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.)
1 A Safety A 1 1a weld OD N/A N/A 4 N/A ~1/2 N/A ~1/2 N/A ~1/2 N/A ~1/2 2 A Safety B 2 1a weld ID N/A N/A 1 1/2 5/8 3 E Relief 3 1a weld OD N/A N N/A N/A N/A 4 E Safety C 4 1a weld ID<22% N/A N N/A N/A N/A 5 ID 82 Y N/A N/A N/A H Safety A 5 1a weld 6 OD 82 Y N/A N/A N/A 7 F Safety A 6 1b NR NR NR NR NR NR NR 8 B Relief 7 2a weld OD 182 N/A 1 0.5 0.375 9 C Safety A 8 2b NR NR NR NR NR NR NR 10 C Safety B 9 2b NR NR NR NR NR NR NR 11 C Safety C 10 2b NR NR NR NR NR NR NR 12 D Safety A 11 3 butter N/A N/A Y N/A N/A N/A 13 butter ID 82 Y N/A N/A ~0.3 E Spray 12 4 14 weld OD N/A N N/A N/A N/A 15 C Spray 13 5 NR NR NR NR NR NR NR 16 ID N/A N/A 5 1.5 5/16 3.75 0.5 2 3/16 2.5 5/16 2 5/16 A Surge 14 8 weld 17 OD N/A N/A 3 2.5 0.5 2 0.5 1 3/16 18 E Surge 15 8 weld ID<10% 82 N 3 N/A N/A N/A N/A N/A N/A 19 butter N/A 82 Y 1 N/A N/A 20 OD 182 N/A 2 1.75 0.875 1.5 1 B Surge 16 8 21 weld ID 182 N/A 1 1.0 0.625 22 ID 182 N/A 1 4 0.75 Notes:
- 1. For Designs #2a, #2b, and #5, liner directly covers DM weld.
- 2. For Design #4, liner does not extend to most of DM weld.
- 5. NR = Information not yet reported (or may not be available)
- 6. N/A = Information not available
- 7. Weld repair entries for Plants C and F are preliminary.
71 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Nozzle Geometry and Repair History PRELIMINARY Weld Repair Summary Table (contd)
- Defect Defect/Repair Defect/Repair Defect/Repair Defect/Repair Defect/Repair Defect/Repair ID/OD Alloy PWHT or Area #1 Area #2 Area #3 Area #4 Area #5 Area #6 Table Plant Nozzle Nozzle Design Buttering (% 82 or after Repair Length Depth Length Depth Length Depth Length Depth Length Depth Length Depth Line Code Type Count # or Weld circ.) 182 Repair? Areas (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.) (in.)
WC1 N/A 82/182 Y N/A N/A N/A WC2 ID+OD 82 Y 2 1/2 7/16ID 1 7/16OD WC3 butter OD 182 Y 1 1 3/4 WC4 J Relief WC1 1a ID 82 Y 3 3/4 3/4 2-1/4 3/4 1/2 3/4 WC5 OD 182 Y 3 1 3/4 2-1/4 3/4 1/2 3/4 WC6 OD 82 N/A 1 1-1/4 1/2 weld WC7 ID 82 N/A 1 1/2 1/2 WC8 butter N/A 182 Y N/A N/A 1/8 J Safety A WC2 1a WC9 weld ID 82 N/A 2 1-1/4 11/32 7/8 11/32 WC10 82 N/A 6 2-1/2 3/4 1 1/2 1-1/2 1/2 1 1/2 2-1/2 3/4 2-1/2 3/4 J Safety B WC3 1a weld ID WC11 82 N/A 6 1-1/2 1/2 1-1/4 1 3/4 7/8 1-1/2 3/8 1 1-1/16 1/2 1/2 WC12 J Spray WC4 4 butter lip/bondline 82 Y N/A N/A N/A WC13 butter OD 182 Y 2 7/8 9/16 1-1/8 1 J Surge WC5 8 WC14 weld ID 82 Y 1 1 7/16 Notes:
- 1. For Designs #2a, #2b, and #5, liner directly covers DM weld.
- 2. For Design #4, liner does not extend to most of DM weld.
- 5. NR = Information not yet reported (or may not be available)
- 6. N/A = Information not available
- 7. Weld repair entries for Plants C and F are preliminary.
72 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Welding Residual Stress Conclusions of Previous DEI Work for EPRI (MRP-106, etc.)
Welding residual stresses are high and a significant contributor to butt weld PWSCC The generic welding residual stress model is conservative for the as-designed case without repairs Weld repairs from the ID surface (360° or partial-arc) significantly increase ID surface stresses
- Generic welding residual stress model does not bound FEA results for cases involving repairs from the ID surface Deep partial-arc weld repairs from the OD surface have high restraint and may produce similar through-wall stress distributions as for cases of ID repairs depending on depth of repair
- Generic welding residual stress model does not bound FEA results for some cases involving partial-arc repairs from the OD surface High stresses for cases involving partial-arc repairs are limited to the repaired area
- Expected to produce cracks limited to the repaired area, not 360° 73 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Piping Butt Weld WRS - Literature Review Preliminary Conclusions Piping Butt Welds Without Repairs:
- Stress measurements show that welding start/stops can produce variations in axial and hoop stress on the order of or greater than the material yield strength over circumferential arc lengths of 15° to 20° Piping Butt Welds With Repairs:
- Weld repairs generally increase the magnitude of maximum tensile axial residual stress
- Location of maximum axial tensile stresses can be in the repair zone or possibly opposite the repair zone depending on the location of the repair relative to the original weld start/stop location
- Weld cap removal provides little benefit in reducing welding residual stresses, particularly on the weld ID
- Short, deep repairs generally result in greater increases in axial tensile residual stresses 74 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation of WRS Inputs Approach A two-step process to model validation is envisioned:
- Validation of residual stress assumptions based on available stress measurements, model predictions, and the general WRS literature
- Validation of the overall crack growth model based on available destructive examinations results for weld metal applications and other information Various sources of WRS information will be sorted and organized to support range of WRS cases considered in the calculations:
- Mockup stress measurements
- Stress measurements on removed plant components
- Various FEA models including DEI, SI, EMC2, etc.
- General WRS literature
- International round robin, if needed details can be made available 75 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation of WRS Inputs Approach (contd)
In past comparisons, the results of the DEI WRS model have shown reasonable agreement versus measured WRS:
- Measured CRDM nozzle mockup stress
- Measured BWR shroud support weld stress
- Measured CRDM nozzle ovality 76 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Crack Growth Rate Equation Sensitivity cases will examine the effect of main uncertainties in the MRP-115 CGR equation:
- Uncertainty in the SIF power-law exponent (nominal 1.6)
- Uncertainty in power-law constant (only time scaling factor that would affect time between leakage and rupture but not whether leakage prior to rupture)
The following factors are not expected to be explicitly evaluated using the FEACrack software
- Lower CGR for Alloy 82 root passes versus Alloy 182 passes (factor of 2.6)
- Lower CGR for growth perpendicular to dendrite solidification direction (factor of 2.0)
No credit being taken for a SIF threshold 77 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
MRP-115 Crack Growth Rate Equation Screened MRP Lab CGR Database for Alloys 82/182/132 1.E-08 1.E-08 MRP-21 Curve MRP-21 Curve for Alloy 182 for Alloy 182 Crack Growth Rate, da /dt (m/s) Crack Growth Rate, da /dt (m/s) 1.E-09 1.E-09 MRP-55 Curve MRP-55 Curve 1.E-10 for Alloy 600 1.E-10 for Alloy 600 1mm/yr 1mm/yr 1.E-11 1.E-11 All CGRs are adjusted to account All CGRs are adjusted to account for percentage engagement across for percentage engagement across the crack front but not alloy type the crack front but not alloy type or crack orientation or crack orientation 1.E-12 1.E-12 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 Stress Intensity Factor, K (MPam) Stress Intensity Factor, K (MPam)
Average CGR data for Alloys 182/132 Average CGR data for Alloy 82 after after screening (43 points) screening (34 points) 78 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
MRP-115 Crack Growth Rate Equation Distribution of Screened Data by Weld Factor The variability in weld factor from the statistical evaluations of laboratory CGR data in MRP-115 will be used to investigate the effect of uncertainty in the power-law constant 1.0 Weld factors for 19 welds of Alloy 82/182/132 0.9 material with fit log-normal distribution (most likely estimator), K th = 0, and best fit 0.8 Cumulative Distribution F 75th Percentile 0.7 0.6 9 182 Welds 0.5 Median 8 82 Welds 2 132 Welds 0.4 Log-Normal Fit 0.3 25th Percentile 0.2 The Alloy 82 data have been normalized (increased) by applying a factor of 2.61:
0.1 1/f alloy = 2.61 0.0 0.1 1. 10.
Weld Factor, f weld 79 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
MRP-115 Crack Growth Rate Equation Recommended Disposition Curves (325°C) 1.E-08 MRP-115 Curve for Alloy 82 The reference temperature for the CGR = (1.5x10-12/2.6)K 1.6 MRP curves is 325°C (617°F); the recommended thermal activation Crack Growth Rate, da /dt (m/s)
MRP-115 Curve for Alloy 182/132 energy for temperature adjustment CGR = 1.5x10-12K 1.6 is 130 kJ/mole (31.0 kcal/mole),
1.E-09 the same value recommended in MRP-55 for base metal.
Laboratory testing indicates that the CGR for Alloy 82 is on average 1.E-10 2.6 times lower than that for Alloy 182/132, so the MRP-115 curve 1 mm/yr for Alloy 82 is 2.6 times lower than the curve for Alloy 182/132.
1.E-11 For crack propagation that is MRP-55 Curve for clearly perpendicular to the Alloy 600 Base Metal dendrite solidification direction, a factor of 2.0 lowering the CGR may be applied to the curves for Alloy 182 (or 132) and Alloy 82.
1.E-12 0 10 20 30 40 50 60 70 80 Stress Intensity Factor, K (MPam) 80 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Effect of Multiple Cracks As demonstrated by practical experience such as apparently for the Wolf Creek pressurizer surge nozzle, there is the possibility of multiple growing flaws connected to the weld ID Sensitivity cases will investigate the effect of multiple crack initiation Several potential approaches are being considered:
- Enveloping of multiple initial flaws with one modeled flaw
- Modeling of a part-depth 360° flaw with a variable depth around the circumference
- Static FEA SIF modeling of two separated flaws to investigate influence of each flaw on the other as a function of their separation on the weld ID See Quest Reliability, LLC slides on this topic 81 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Crack Interaction Greg Thorwald, Ph.D.
303-415-1475
Coplanar Cracks Fig 2.57 Two Coplanar cracks, interaction magnifies KI at nearest crack tips
Crack Tip Interaction Fig. 2.58 Interaction of two identical coplanar through-wall cracks in an infinite plate; KI magnified at crack tip B
Parallel Cracks Fig. 2.59 Parallel cracks; shielding causes decrease in KI
Parallel Crack Shielding Fig. 2.60 Interaction between two identical parallel through-wall cracks in an infinite plate; crack tip shielding decreases KI compared to a single crack
Crack Interaction Models
Use a single crack and a symmetry plane near the crack tip to get K interaction
Include multiple cracks in a model
User-defined geometry method from FEACrack
- Same or different crack shapes
- Adjust distance between crack fronts
Proposed Case Matrix Other Items: Initial Flaw Geometry Sensitivity cases will investigate the effect of initial flaw geometry
- Initial depth
- Initial aspect ratio (2c/a) or 360° uniform depth surface flaw
- Initial shape factor (e.g., low shape factor to semi-ellipse to close to uniform depth)
Cases for WC relief nozzle dimensions indicate that crack profile upon through-wall penetration (or upon crack arrest) is insensitive to initial flaw geometry 82 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Other Items: Effect of Elastic-Plastic Redistribution of Load Cases to investigate effect of elastic-plastic redistribution of load given high WRS at ID surface
- The applied WRS profile may be modified to investigate this effect as implied in the following figure: 60 0° example of 22.5° 50 possible stress 45° 67.5° profile based 90° 40 on modified Axial Stress with Residual Stress (ksi) 112.5° 135° WRS Plot for WC relief 30 157.5° 180°
= 0° to 180° nozzle showing axial 20 stress profile at various 10 positions around circumference (dead 0 weight, thermal pipe -10 load, end cap pressure, = 0° is circumferential position of maximum bending axial stress;
-20 and assumed WRS) = 90° is bending neutral axis
-30 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 Normalized Distance from ID Surface, (r-ri)/t 83 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Other Items: Crack Inserted into WRS FEA Model It is planned for selected sensitivity cases, a crack will be inserted directly into the 3-dimensional DEI WRS FEA model
- Considers detailed geometry effects
- Considers detailed predicted WRS field, including modeling of weld repairs
- Considers local thermal stress due to differential thermal expansion (Q-stress) 84 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Proposed Case Matrix Other Items: Crack Inserted into WRS FEA Model This type of approach was applied in a preliminary fashion by DEI in 2005 for a reactor pressure vessel outlet nozzle 1 1 RPV Outlet Nozzle 90 Degree ID R - Operating Conditions RV Outlet Nozzle ID90 Repair - 20% TW Crack, 6:1 Aspect Ratio Intact Axial Operating Stresses Axial Stress Redistribution with Circ Crack The FEACrack enhancement for this work will reduce the effort required to insert the crack mesh into the full welding residual stress model 85 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Additional Topics - Industry and NRC Critical Crack Size Calculations
- Industry Validation studies and WRS mockups
- Industry Benchmarking NRC/Industry K Solutions for the Advanced FEA Calculations
- Industry
- NRC Leak-rate Calculations
- Industry 86 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Calculating Critical Crack Size Approach Scoping calculations have been completed examining the dependence of critical crack size for idealized surface and through-wall crack geometries for the dimensions and load parameters for the group of 51 subject welds
- Effect of load types included
- Effect of assumed flow strength
- Effect of thin-wall vs. thick-wall equations
- Effect of surface vs. through-wall crack geometry
- Effect of inclusion of Z-factor The flow strength in the net section collapse calculations will be based on the safe end material, given the potential for the crack to be located close to the safe end Crack stability for each calculated crack growth progression (surface crack and through-wall) is being checked using a spreadsheet implementation of the NSC solution published by Rahman and Wilkowski for an arbitrary crack profile, assuming thin-wall equilibrium 87 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Calculating Critical Crack Size Approach (contd)
The Arbitrary Net Section Collapse (ANSC) software by Structural Integrity Associates is also being applied:
- To verify the spreadsheet implementation of Rahman and Wilkowski (exact agreement has been obtained)
- To investigate cases in which the moment direction is not assumed to be lined up with the symmetry (i.e., center) point on the crack Consider secondary stresses as appropriate
- See separate presentation by Pete Riccardella of SI Apply Z-factor to reduce supportable moment to consider effect of EPFM failure mechanism for small calculated values of the nondimensional plastic zone parameter
- See separate presentation by Pete Riccardella of SI As described above, the crack growth progression is also checked for the potential effect of local ligament collapse
- For complex crack profile at point leakage becomes detectable
- For complete growth progression to examine potential effect on the progression 88 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Calculating Critical Crack Size Defining Pipe Loads for Critical Crack Size Each category of loading is being treated as follows in the critical crack size calculation that defines the growth end point:
- Deadweight: Same as for growth
- Internal pressure: Same as for growth
- Normal pipe thermal expansion: Treatment of secondary stresses discussed in presentation slides by Pete Riccardella of SI
- Normal thermal stratification pipe bending moment (surge nozzle only): Treatment of secondary stresses discussed in presentation slides by Pete Riccardella of SI
- Thermal stratification pipe bending moment for plant transients (surge nozzle only):
Treatment of secondary stresses discussed in presentation slides by Pete Riccardella of SI
- Welding residual stress: Not included in limit load or EPFM mechanisms
- Local thermal stress due to differential thermal expansion (Q-stress): Not included as this is a local secondary stress component
- Seismic loads: SSE load considered for faulted cases 89 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Calculating Critical Crack Size Force and Moment Equilibrium for Arbitrary Crack Rahman and Wilkowski have published the thin-wall solution for axial force and applied moment equilibrium given a circumferential flaw with arbitrary depth profile DEI has implemented this solution in spreadsheet form The solution is being applied to crack profiles calculated by the FEACrack software
- Case 1: Entire crack in tension
- Case 2a: Part of crack in compression zone with crack taking compression
- Case 2b: Part of crack in compression zone with crack not taking compression Arbitrary Net Section Collapse (ANSC) software by Structural Integrity Associates used to validate spreadsheet calculation
- ANSC also allows arbitrary moment direction, unlike S. Rahman and G. Wilkowski, Net-Section-Collapse Analysis of Circumferentially Cracked CylindersPart I: Arbitrary-Shaped Cracks Rahman and Wilkowski and Generalized Equations, Engineering Fracture Mechanics, Vol. 61, pp. 191-211, 1998.
90 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Calculating Critical Crack Size Safe End Flow Strength Because any hypothetical SCC could be located close to the safe end material, the safe end flow strength will be applied in the limit load crack stability calculations Design drawings and CMTR information for 9 subject plants indicate that the stainless steel safe ends are fabricated from the following materials:
- SA182 Grade F316L in most cases
- SA182 Grade F316 in the other cases The following two slides show application of CMTR data to determine likely range of flow strength at temperature for the subject safe ends
- Flow strength taken as average of yield and ultimate strength
- Assumed temperature dependence between room temperature and 650°F based on Code temperature dependences for these materials: S650°F = CMTRx(Code650°F/CodeRT)
The results of this investigation support the use of the 45.6 ksi flow strength value assumed in the NRC calculations for the WC safe end 91 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
92 CMTR Safe End Strength Values (ksi) 0 10 20 30 40 50 60 70 80 0.00 01 A - Re (7.75x5.17) 0.50 1.00 1.50 02 A - SA (7.75x5.17) 2.00 2.50 03 A - SB (7.75x5.17) 3.00 4.75 04 A - SC (7.75x5.17) 5.25 5.75 6.25 05 E - Re (7.75x5.17) 6.75 7.25 06 E - SA (7.75x5.17) 7.75 8.25 07 E - SB (7.75x5.17) 8.75 9.25 08 E - SC (7.75x5.17) 9.75 10.25 11.00 CMTR YS CMTR FS 09 H - Re (7.75x5.17) 11.50 CMTR UTS 12.00 10 H - SA (7.75x5.17) 12.50 13.00 11 H - SB (7.75x5.17) 13.75 14.25 14.75 12 H - SC (7.75x5.17) 15.25 15.75 WC1 J - Re (7.75x5.17) 16.25 16.75 14 F - SA (8x5.19) 17.25 17.75 18.25 15 F - SB (8x5.19) 18.75 19.25 16 F - SC (8x5.19) 19.75 20.25 17 B - Re (7.75x5.62) 20.75 21.25 18 B - SA (7.75x5.62) 21.75 22.25 22.75 19 B - SB (7.75x5.62) 23.25 23.75 20 B - SC (7.75x5.62) 24.25 24.75 21 G - Re (7.75x5.62) 25.25 25.75 Flow strength (FS) taken as average of 26.25 22 G - SA (7.75x5.62) 26.75 27.25 Project Review Meeting: Advanced FEA Crack Growth Evaluations 23 G - SB (7.75x5.62) 27.75 28.25 24 G - SC (7.75x5.62) 28.75 29.25 25 C - Re (7.75x5.62) 29.75 30.25 30.75 26 C - SA (7.75x5.62) 31.25 31.75 27 C - SB (7.75x5.62) 32.25 32.75 28 C - SC (7.75x5.62) 33.25 33.75 34.25 29 D - Re (8x4.937)
YS and UTS listed in safe end CMTR.
34.75 35.25 30 D - SA (8x4.937) 35.75 36.25 31 D - SB (8x4.937) 36.75 37.25 37.75 32 D - SC (8x4.937) 38.25 CMTR Strength Values for Safe Ends 38.75 33 I - Re (8x4.937) 39.25 39.75 34 I - SA (8x4.937) 40.25 40.75 35 I - SB (8x4.937) 41.25 41.75 42.25 36 A - Sp (5.81x4.01)
Calculating Critical Crack Size 42.75 43.25 37 E - Sp (5.81x4.01) 43.75 44.25 WC5 J - Sp (5.81x4.01) 44.75 45.25 45.75 39 G - Sp (5.81x4.25) 46.25 46.75 40 C - Sp (5.81x4.25) 47.25 47.75 41 F - Sp (8x5.695) 48.25 48.75 42 D - Sp (5.188x3.062) 49.25 49.75 50.25 43 I - Sp (5.188x3.25) 50.75 May 8, 2007, North Bethesda, Maryland 51.25 44 A - Su (15x11.844) 51.75 52.25 45 E - Su (15x11.844) 52.75 53.25 53.75 46 H - Su (15x11.844) 54.25 54.75 WC6 J - Su (15x11.844) 55.25 55.75 48 G - Su (15x11.844) 56.25 56.75 57.25 49 C - Su (15x11.875) 57.75 58.25 50 D - Su (13.063x10.125) 58.75 59.25 51 I - Su (13.063x10.125) 59.75 0 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
93 Safe End Strength Values (ksi) at 650°F Based on CMTR Data 0 10 20 30 40 50 60 70 80 0.
0 0 01 A - Re (7.75x5.17) 0.
7 5 02 A - SA (7.75x5.17) 1.
5 0 2.
2 5 03 A - SB (7.75x5.17) 3.
0 0 04 A - SC (7.75x5.17) 5.
0 0 5.
7 5 05 E - Re (7.75x5.17) 6.
5 0 06 E - SA (7.75x5.17) 7.
2 5 8.
0 0 07 E - SB (7.75x5.17) 8.
08 E - SC (7.75x5.17) 5 0 CMTR UTS 10
.2 09 H - Re (7.75x5.17) 5 11
.2 5
12 10 H - SA (7.75x5.17) .0 0
12
.7 5
11 H - SB (7.75x5.17) 13
.7 5
14 12 H - SC (7.75x5.17) .5 0
15
.2 5
WC1 J - Re (7.75x5.17) 16
.0 0
16 14 F - SA (8x5.19) .7 5
17
.5 0
15 F - SB (8x5.19) 18
.2 5
19 16 F - SC (8x5.19) .0 0
19
.7 5
Flow strength (FS) taken as average of YS and UTS adjusted from 17 B - Re (7.75x5.62) 20
.5 0
21
.2 18 B - SA (7.75x5.62) 5 22
.0 0
19 B - SB (7.75x5.62) 22
.7 5
23
.5 20 B - SC (7.75x5.62) 0 24
.2 5
21 G - Re (7.75x5.62) 25
.0 0
25
.7 22 G - SA (7.75x5.62) 5 26
.5 0
23 G - SB (7.75x5.62) 27
.2 5
Project Review Meeting: Advanced FEA Crack Growth Evaluations 28
.0 24 G - SC (7.75x5.62) 0 28
.7 5
25 C - Re (7.75x5.62) 29
.5 0
CMTR values using ASME Code temperature dependence for YS 30
.2 26 C - SA (7.75x5.62) 5 31
.0 0
31 27 C - SB (7.75x5.62) .7 5
32
.5 0
28 C - SC (7.75x5.62) 33
.2 5
34 29 D - Re (8x4.937) .0 0
34
.7 5
30 D - SA (8x4.937) 35
.5 0
36 31 D - SB (8x4.937) .2 5
37
.0 0
32 D - SC (8x4.937) 37
.7 5
38 33 I - Re (8x4.937) .5 0
39
.2 5
and UTS for SA182 Grade F316L or Grade F316, as appropriate.
34 I - SA (8x4.937) 40
.0 0
40
.7 35 I - SB (8x4.937) 5 41
.5 0
36 A - Sp (5.81x4.01) 42
.2 5
Calculating Critical Crack Size 43
.0 37 E - Sp (5.81x4.01) 0 43
.7 5
WC5 J - Sp (5.81x4.01) 44
.5 0
45
.2 39 G - Sp (5.81x4.25) 5 46 Estimated Safe End Flow Strength at 650°F
.0 0
40 C - Sp (5.81x4.25) 46
.7 5
47
.5 41 F - Sp (8x5.695) 0 48
.2 5
49 42 D - Sp (5.188x3.062) .0 0
49
.7 43 I - Sp (5.188x3.25) 5 50
.5 0
51 44 A - Su (15x11.844) .2 May 8, 2007, North Bethesda, Maryland 5
52
.0 0
45 E - Su (15x11.844) 52
.7 5
53 46 H - Su (15x11.844) .5 0
54
.2 5
WC6 J - Su (15x11.844) 55
.0 0
55 48 G - Su (15x11.844) .7 5
56
.5 0
49 C - Su (15x11.875) 57
.2 5
58 50 D - Su (13.063x10.125) .0 0
58
.7 5
51 I - Su (13.063x10.125) 59
.5 0
0 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Work Status Validation Planning Validation planning is in progress, including consideration of application of the following:
- MRP-107 laboratory study for Alloy 182 pressure capsules
- Duane Arnold circumferential crack
- Ringhals 3 reactor vessel outlet nozzle axial flaws left in service
- Tsuruga 2 pressurizer safety and relief nozzle axial through-wall flaw associated with OD weld repairs
- VC Summer reactor vessel outlet nozzle leaking flaw, primarily in axial direction For other PWR experience with possible PWSCC in Alloy 82/182 piping butt welds, destructive examinations have not been performed 94 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation Planning MRP-107 Lab Study of PWSCC in Alloy 182 The report summary for MRP-107 (EPRI 1009399, 2004) includes the following:
- Abstract: Detailed examinations of Alloy 182 capsule samples containing PWSCC established the relationship between crack initiation sites and the microstructure of the weld metal. These examinations also identified microstructural features that facilitate or arrest PWSCC propagation. Crack initiation only occurred at high angle, high energy, dendrite packet grain boundaries, and growth apparently arrested at low energy boundaries due to low angular misorientation or coincidence of lattice sites. The work also revealed important findings with regard to crack geometries, in particular what aspect ratios may develop during PWSCC of nickel-base (Ni-base) weld metals.
- The cracks exhibited an unusual aspect ratio in that they never showed a large lateral surface extent, even when they extended through the wall thickness. This is a very different feature compared to PWSCC in Ni-base alloys such as Alloy 600. The aspect ratio is thought to relate to indications of crack arrest observed at low energy grain boundaries in Alloy 182.
95 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation Planning Duane Arnold Circumferential Crack The Duane Arnold crack is being considered as a potential comparison case From MRP-113: Crack initiation and growth were attributed to the presence of a fully circumferential crevice that led to development of an acidic environment because of the oxygen in the normal BWR water chemistry, combined with high residual and applied stresses as a result of the geometry and nearby welds. The water chemistry conditions that contributed to cracking at Duane Arnold do not exist for the case of Alloy 82/182 butt welds in PWR plants.
96 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation Planning BWR Piping Experience with Circ Cracks (MRP-113)
Arc Length and Depth for Circumferential Cracks in BWR Plants (Some Points Represent Multiple Cracks) 120%
100%
Crack Depth (% Thru Wall) 80%
14 in. Nozzles 60% 12 in. Nozzles 10 in. Nozzles Duane Arnold 40% Circ Flaw 20%
0 30 60 90 120 150 180 210 240 270 300 330 360 Crack Length (deg) 97 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Validation Planning Ringhals 3 Reactor Vessel Outlet Nozzle Alloy 82/182 Weld 1.E-08 MRP-115 Curve for Alloy 182/132 MRP-115 Curve for Alloy 82 MRP-115 Curve for Alloy 182/132 CGR = (1.5x10-12/2.6)K 1.6 MRP-115 Curve for Alloy 82 Crack Growth Rate, da /dt (m/s)
CGR = 1.5x10-12K 1.6 MRP-55 Curve for Alloy 600 1.E-09 Ringhals 3 / Crack 1 / Depth Increase from 2000 to 2001 Ringhals 3 / Crack 2 / Depth Increase from 2000 to 2001 1.E-10 1 mm/yr The points for the Ringhals 3 hot leg safe end weld cracks are based on the depth measurements made in 2000 and 2001 and the stress intensity factors 1.E-11 calculated by Ringhals (points shown at average of initial and final K corresponding to best estimate initial and final depths). The Ringhals data were adjusted from the operating temperature of 319°C (606°F) to the reference temperature of 325°C (617°F) using the activation energy of 130 kJ/mole (31.0 kcal/mole).
1.E-12 All curves adjusted to 325°C 0 10 20 30 40 50 60 70 80 using an activation energy of Stress Intensity Factor, K (MPam) 130 kJ/mole (31.0 kcal/mole) 98 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
WRS Mockups EPRI/SI Preemptive Weld Overlay (PWOL) Mockup EPRI and Structural Integrity Associates (SI) have recently completed a project that included fabrication of a mockup of a general vessel nozzle configuration
- Attached to 10NPS pipe The next 10 slides include the surface stress measurements made on the PWOL mockup before the weld overlay was applied This information may be useful as part of the validation studies 99 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
WRS Mockups EPRI/SI Preemptive Weld Overlay (PWOL) Mockup Drawing 100 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Finite Element Model 101 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Analysis Results Axial Residual Stresses Pre-PWOL Post-PWOL 102 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Analysis Results Hoop Residual Stresses Pre-PWOL Post-PWOL 103 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Residual Stress Measurements 6.820 6.320 3.820 2.9 2.5 ID Weld Repair CS SS 5.1 5.5 5.9 6.320 Surface measurements on ID and OD prior to Overlay Weld
@ 45 and 135-dgrees OD @ weld centerline, center of butter, and one additional location .4-in. from weld butter.
104 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup ID with 90° Weld Repair & XRD Measurement Locations 135° 90° 0° 45° ID Weld Repair 105 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Axial Residual Stress Results: Pre-Overlay ID Surface Axial Stress Pre-Overlay Analysis vs. Measurements 100 80 60 ID Weld Repair 0° 45° 90° 135° 40 20 Stresses (ksi) 0 0 0.5 1 1.5 2 Analysis
-20 XRD 45
-40 XRD 0
-60 XRD 90
-80 A-182 Thru-wall SS Clad A-182 Clad on ID Butter Region on ID on ID
-100 Dist. from DMW Centerline (in)
(towards nozzle) 106 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Axial Residual Stress Results: Post-Overlay ID Surface Axial Stress Post-Overlay Analysis vs. Measurements 100 80 60 ID Weld Repair 0° 45° 90° 135° 40 20 Stresses (ksi) 0 0 0.5 1 1.5 2 Analysis
-20 XRD 45 XRD 135
-40 Hole Drill
-60
-80 A-182 Thru-wall SS Clad A-182 Clad on ID Butter Region on ID on ID
-100 Dist. from DMW Centerline (in)
(towards nozzle) 107 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Hoop Residual Stress Results: Pre-Overlay ID Surface Hoop Stress Pre-Overlay Analysis vs. Measurements 100 80 60 ID Weld Repair 0° 45° 90° 135° 40 20 Stresses (ksi) 0 0 0.5 1 1.5 2 Analysis
-20 XRD 45
-40 XED 0
-60 XRD 90
-80 A-182 Thru-wall SS Clad A-182 Clad on ID Butter Region on ID on ID
-100 Dist. from DMW Centerline (in)
(towards nozzle) 108 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
EPRI/SI PWOL Mockup Hoop Residual Stress Results: Post-Overlay ID Surface Hoop Stress Post-Overlay Analysis vs. Measurements 100 80 60 ID Weld Repair 0° 45° 90° 135° 40 20 Stresses (ksi) 0 0 0.5 1 1.5 2 Analysis
-20 XRD 45 XRD 135
-40 Hole Drill
-60
-80 A-182 Thru-wall SS Clad A-182 Clad on ID Butter Region on ID on ID
-100 Dist. from DMW Centerline (in)
(towards nozzle) 109 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Benchmarking/Verification of SIF Calculation Approach Benchmarking and verification tasks are in progress to verify that the FEACrack/ANSYS software including new modules is producing mathematically correct answers Surface and through-wall crack test cases are being compared against published solutions
- Newman-Raju published solutions
- EPRI Ductile Fracture Handbook (Zahoor) solutions
- WRC Bulletin 471 (Anderson, et al.)
- partial-arc semi-elliptical flaws
- uniform-depth axisymmetric flaw and loading
- Anderson solution for through-wall cracks in cylinders
- Cases performed by NRC contractor (EMC2) for selected custom crack profiles
- Other published solutions as available DEI is also performing general commercial software dedication of the FEACrack software per EPRI guidance 110 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Benchmarking/Verification of SIF Calculation Past Example 1: TW Circ Flaw in Cylinder Crack Face Axially loaded through-wall flaw circumferential in cylinder Crack Front Key Hole SIF for model compared with EPRI Ductile Fracture Handbook results Symmetry Boundary Condition
- R/t = 10, max arc = 180° Results agree within 10%
Crack Face KI Calculated Using K Calculated per Crack Length Zahoor1 FEA Model Test Case 30° 2.9 ksiin 2.9 ksiin 80° 6.6 ksiin 7.1 ksiin 130° 12.7 ksiin 13.6 ksiin 180° 24.0 ksiin 26.5 ksiin Symmetry Boundary Conditions 111 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Benchmarking/Verification of SIF Calculation Past Example 2: Angled Crack in a Plate Model test performed to examine J-integral results with combined crack opening modes (I and II)
- Flaw 45° from horizontal Model dimensions selected such that KI = KII = 6.3 ksiin Combined J-integral = 2.62 in-lbs/in2 FEA results for average J-integral on crack front = 2.66 in-lbs/in2 112 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Benchmarking/Verification of SIF Calculation Past Example 3: Corner Crack on Plate Face Applied crack face pressure of 50 ksi Rooke and Cartwright peak SIF = 72.2 ksiin FEA results = 69.6 ksiin 113 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Benchmarking/Verification of SIF Calculation Verification and Validation Cases in Draft Phase I Calc Table 1. Inside Diameter Scaled up to Ri/t = 3 for Direct Comparison to Anderson Correlation Based on NRC Assumed WRS Distribution (with Scaled up Loading Resulting in Comparable Axial Stress Distribution) 0.5 0.5 Anderson (ksi-in ) DEI FEA (ksi-in ) Deviation No. crack Ri/t a/t 2c/a 2 (deg) Ksurf Kdeep Ksurf Kdeep Ksurf Kdeep V1 semi-elliptical 3 0.2 16 61.1 19.8 19.5 28.7 21.1 8.9 1.6 V2 semi-elliptical 3 0.4 16 122.2 24.0 6.7 31.9 9.0 7.8 2.3 V3 semi-elliptical 3 0.6 16 183.3 25.5 10.3 30.8 12.5 5.4 2.1 V4 semi-elliptical 3 0.8 16 244.5 25.0 29.6 27.9 29.9 2.9 0.3 Table 2. Inside Diameter Scaled up to Ri/t = 3 for Direct Comparison to Anderson Correlation Based on Actual FEA WRS Distribution Attained (with Scaled up Loading Resulting in Comparable Axial Stress Distribution) 0.5 0.5 Anderson (ksi-in ) DEI FEA (ksi-in ) Deviation No. crack Ri/t a/t 2c/a 2 (deg) Ksurf Kdeep Ksurf Kdeep Ksurf Kdeep V1 semi-elliptical 3 0.2 16 61.1 18.6 18.9 28.7 21.1 10.1 2.2 V2 semi-elliptical 3 0.4 16 122.2 22.6 6.9 31.9 9.0 9.3 2.1 V3 semi-elliptical 3 0.6 16 183.3 23.8 9.5 30.8 12.5 7.0 3.0 V4 semi-elliptical 3 0.8 16 244.5 23.3 26.5 27.9 29.9 4.6 3.4 Table 3. Selected FEA Cases for Case of No WRS Loading for Comparison to Anderson Correlation Extrapolated Down to Ri/t = 2.004 Anderson (ksi-in0.5) DEI FEA (ksi-in0.5) Deviation No. crack Ri/t a/t 2c/a 2 (deg) Ksurf Kdeep Ksurf Kdeep Ksurf Kdeep 3 semi-elliptical 2.004 0.1 15 42.9 2.6 6.2 2.9 6.4 0.4 0.2 15 semi-elliptical 2.004 0.3 5 42.9 7.2 9.9 7.8 10.1 0.6 0.2 18 semi-elliptical 2.004 0.3 21 180.1 2.4 12.2 2.3 12.1 -0.1 -0.1 20 semi-elliptical 2.004 0.3 30 257.3 1.5 13.0 0.6 12.2 -0.9 -0.8 114 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Leak Rate Calculations Approach PICEP and SQUIRT software models are being applied using crack morphology parameters appropriate to intergranular nature of PWSCC
- Wilkowski presentation at 2003 NRC Conference on Alloy 600 PWSCC in Gaithersburg, Maryland As a scoping tool, PICEP is being applied to calculate COD and leak rate as a function of assumed piping load
- See example on next slide For each FEA crack growth progression case, the leak rate as a function of time will be calculated on the basis of the COD directly from the through-wall portion of the complex crack FEA model
- The COD dependence through the wall thickness in the through-wall crack region will be examined to determine the controlling COD parameters 115 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Leak Rate Calculations Example Scoping Results for WC Relief Nozzle DM Weld 100.000 Full Moment (275 in-kips)
Half Moment Quarter Moment 10.000 Zero Moment Leak Rate (gpm at 70°F) 1.000 0.100 PRELIMINARY 0.010 0.001 0 20 40 60 80 100 120 140 160 180 200 Total Crack Arc Length (deg) 116 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Plans for Next Meeting(s)
Previously tentatively scheduled meetings:
- May 29 telecon: Telcon on Phase II progress
- June 19 meeting: Present Phase II results 117 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland
Meeting Summary and Conclusions Industry NRC 118 Project Review Meeting: Advanced FEA Crack Growth Evaluations May 8, 2007, North Bethesda, Maryland