ML050240096
| ML050240096 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/09/2004 |
| From: | Arizona Public Service Co |
| To: | Office of Nuclear Reactor Regulation |
| Fields M B ,NRR/DLPM,415-3062 | |
| Shared Package | |
| ML050240440 | List: |
| References | |
| Download: ML050240096 (46) | |
Text
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E 1
Nuclear Fuel Update Palo Verde Nuclear Generating Station December 9, 2004 Meeting with US NRC
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E 2
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E 3
Review of 2003-4 March 2003 Meeting with NRR CENTS Implementation Steam Generator Replacement Power Uprate CPC Replacement Dry Cask Storage in Production
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E 4
Agenda Today Fuel Performance Considering Dual LTA Program CEA Replacement Planned License Submittals Dry Cask Storage Update
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E 5
Palo Verde Fuel Performance
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E 6
Fuel & Clad Performance Clad Performance Uprate Conditions High Burnup Leakers Fabrication Issues
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E 7
Integrated Fuel Performance Clad Performance Strategy:
- Advanced Clad Alloys
- Primary Chemistry
- CRUD/Oxide Software
- Low Duty Core Designs Multi Phase Performance Program
- 3876 MW and 3990 MW Conditions Long Range Fuel Inspection Plan
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E 8
Early Learnings in Fuel Performance Evolution of Core Design Strategies
- Low Leakage Checkerboards
- Feed-Face-Feed Strategies
- Modified Checkerboards Unit 2 Cycle 9
- Axial Offset Anomaly (CIPS)
- Fuel Failures Cause of CRUD and Oxidation
- Different Fuel Duty Cycles
- Different Solutions
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E 9
Clad CRUD in Unit 2 Cycle 9 P2L5xx Assembly Face
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E 10 The Two Duty Cycles Typical (U2C13) Core Design Fresh 1x burned 2x burned Reinserts
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E 11 Fuel Performance in Uprate Conditions 3% Power and ~2 oF Inlet Temperature New Steam Generators Increased Clad Oxidation
- Spallation Risk Increased Steaming Rate
- Each 1 oF or 1% Power is Worth 10% Steaming Rate
- Higher Source Term from New Steam Generators
- CRUD & AOA Risk
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E 12 ZIRLOTM Clad Westinghouse Low Tin Zirconium Based Alloy First Implementation in Unit 2 Cycle 11
- Protect High Duty 2 Cycle Assemblies Licensing Limitation
- Fuel Duty Index
- Maximum Oxide Thickness 2R11 Inspection Results
- Performance as Expected
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E 13 New Lattice Design First Implementation in Unit 2 Cycle 12
- Protect High Duty First Burn Assemblies Design Concept - Balance Power & Flow
- In-House Designed Based on APS CRUD Model
- Three Enrichments, Four Pin Types Extensive Design Review
- In-House, Westinghouse, URA
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E 14 Crud Model Development Oxide/Crud Measured Thickness 0
5 10 15 20 25 30 35 0
30 60 90 120 150 D i st a nc e f r om bot t om of r o d ( i n. )
µ A5 B4 E7 H5 D3
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E 15 Crud Model Results Rod A5 0
2 4
6 8
10 12 Span 9 Span 8 Span 7 Span 6 Crud Thickness (
µm)
Inferred Calculated Rod B4 0
2 4
6 8
10 12 Span 9 Span 8 Span 7 Span 6 Crud Thickness (
µm)
Inferred Calculated Rod E7 0
2 4
6 8
10 12 Span 9 Span 8 Span 7 Span 6 Crud Thickness (
µm)
Inferred Calculated Rod H5 0
2 4
6 8
10 12 Span 9 Span 8 Span 7 Span 6 Crud Thickness (
µm)
Inferred Calculated
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E 16 Crud Model Results
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E 17 Revised Lattice Design Objectives Smallest Change Possible Change Only Well Understood Lattice Feature(s)
No Operational, Licensing, Manufacturing Impact Minimal Safety Analysis Impact
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E 18 Sample Lattice Comparison 4.05 w/o 3.75 w/o 3.75 w/o Er Previous - 64 Er New - 64 Er 4.29 w/o 3.79 w/o Er 3.79 w/o 3.99 w/o
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E 19 Pin Power Comparison
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E 20 New Lattice CRUD Impact 5.81 7.49 3.25 0
1 2
3 4
5 6
7 8
Average Crud Thickness in Worst Lumped Channel (microns)
U3C9 U2C12C U2C12R Unit and Cycle Average Crud Thickness - 1/8 Core Predicted (100 assembly, 2X source term, flat propensity factor)
Revised Lattice
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E 21 6.95 2.58 1.25 0.5 0
1 2
3 4
5 6
7 A verag e C ru d T h ickn ess in W o rst L u m p ed C h an n el (m icro n s)
U2C9 U3C9 U2C11 U2C12 Unit and Cycle Comparison of Average Crud Thickness - Predicted New Lattice Design, Current Source Term
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E 22 Long Term Fuel Inspection Program Proof of Design Concept
- Davis-Besse: I know because I looked Zirlo New Lattice Other Planned Inspections
- Assembly Bow
- Top Grid
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E 23 Flawless Fuel New Agreement with Westinghouse
- Identify and Investigate All Failures
- Incentive for Flawless Fuel
- Reconstitute Failed Assemblies Sipping in Containment UT in Spent Fuel Pool
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E 24 High Burnup Fuel Performance High Burnup Fuel Failure Trend Loose Top Grid Cells Top Grid Re-Design
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E 25 High Burnup Fuel Failure Trend Mid 90s, Clean Cores Cycle After Cycle Ten Failed First Burn Pins in U2C9 One Failed End Cap Weld (U1C9)
Nine Indications Starting with U2C9 Five of Nine Cycles with 1 or 2 Indications UT Has Failed Repeatedly to Locate Rods Three Identified Grid-Rod Fretting Failures
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E 26
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E 27 Loose Top Grid Cells PV1P Fabrication Campaign Description of Rod Support Features Root Causes
- Bias in Grid Construction Tolerances
- Force-Fit of 20 mil Oversize Guide Tube
- Rod Pushing Table Mis-Alignment
- Weaknesses in Inspection/QA Process
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E 28 Loose Grid Cells & Grid-Rod Fretting Current Zircaloy Top Grid
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E 29 Current Zircaloy Top Grid
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E 30 Top Grid Re-Design Zirc-4 to Inconel 625 Wavy strip to Straight Strip Cantilever Spring Cut-out Double Back-up Arch Accommodation of Expanded Guide Tube Grid to Guide Tube Attachment Change to Top Nozzle (UEF)
- Assembly Length Measurements Spring 2005
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E 31 Proposed Inconel Top Grid
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E 32 Dual LTA Program
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E 33 Long Term Fuel Design Strategy Fuel Contract Timeline
- 12 Years on Westinghouse Contract LTAs Needed to Demonstrate New Design
- 8 Assembly, 3 Cycle LTA Programs AREVA and Westinghouse Designs
- No Current Disaster Back-up to Columbia
- More Options Lead to Better Designs Starts 2005
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E 34 Specific Fuel Design Goals Materials for Higher Burnup/Duty
- Cladding Oxidation
- Dimensional Stability Mixing Grids
- Minimize CRUD
- Increase Thermal Margin Preserving/Increasing Operating Margins Improve Fuel Utilization Overall Robust Design for Flawless Fuel
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E 35 CEA Replacement
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E 36 CEA Replacement Review CEA History Determination of New, Conservative Lifetime Design of New Replacement CEAs Replacement of PLCEAs
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E 37 Review of CEA History CEA Clad Failures Observed - 2001
- Cracks in High Fluence CEA Tips
- Root Cause - IASCC, Inadequate Testing
- U2/U3 With Small Pellet Less Severe All Full Length CEAs Replaced
- Replaced by Design with Smallest Pellet Lifetime Software Abandoned
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E 38 Control Element Assemblies Control Element Assemblies 89 CEAs in 8 groups z 148 inches of B4C poison 4-finger and 12-finger assemblies z B4C wrapped in Feltmetal at bottom 8%
z 12-finger CEAs span 5 assemblies z 688 total fingers B4C Reduced Diameter B4C and Feltmetal region End Plug
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E 39 Determination of New Lifetime Investigated Various Options Monitored YGN Inspections Vendor Adjusted Software Inconel IASCC Threshold Observed Crack in U2C8 CEA 5 Cycle Lifetime Need New CEAs for Fall 2008
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E 40 Design of Future CEAs Now: Unique Feltmetal Design Want:
- Industry Standard AgInCd
- Extended Tip Region CEDM Weight Restrictions
- AgInCd Tip Region
- Boron Carbide for Remainder Lifetime Issues Remain
- 20 EFPY Design Lifetime
- ~12 EFPY Experience Base
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E 41 Replacement of PLCEAs Original Equipment
- Part Length, Part Strength
- Not Subject to Same Failure Mode
- Replacing Now for Prudency Replacements
- Full Length, Part Strength
- Transparent to Safety Analysis
- Tech Spec Change Approved U1 Done -- U3 Done -- U2 Spring 2005
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E 42 New Design PSCEAs Comparison of Part Strength CEAs
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E 43 Planned License Submittals
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E 44 2005 License Submittals (U1 & U3 Power Up-Rate in Review)
TS 3.1.6 Shutdown CEA Insertion Limits TS 5.6.5 Core Operating Limits Report
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E 45 Shutdown CEA Insertion Limits Current T.S. allows insertion to 144.75 withdrawn
- 6.2 into active fuel Safety Analysis only covers insertion to 147.75
- 3.2 into active fuel Shutdown Margin is monitored per Core Data Book
- 147.75 withdrawn, forces higher boron concentration T.S. 3.1.6 rewritten to reference COLR
- Shutdown CEA COLR based on 147.75
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E 46 Core Operating Limits Report One Inconsistent Reference
- CEA Drop Methodology Reference Currently Evaluating Changes
- Update CEA Drop Reference
- Remove CESSAR References
- Update to Power Uprate SER