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#REDIRECT [[PNP 2012-005, Attachment 6, Holtec International Report No. HI-2115004, Licensing Report for Replacement of the Palisades Region 1 Spent Fuel Pool Storage Racks. (Non-Proprietary Version)]]
| number = ML12061A289
| issue date = 02/28/2012
| title = Attachment 6, Holtec International Report No. HI-2115004, Licensing Report for Replacement of the Palisades Region 1 Spent Fuel Pool Storage Racks. (Non-Proprietary Version)
| author name =
| author affiliation = Holtec International
| addressee name =
| addressee affiliation = NRC/NRR
| docket = 05000255
| license number = DPR-020
| contact person =
| case reference number = PNP 2012-005
| document report number = HI-2115004
| document type = Report, Technical
| page count = 304
}}
 
=Text=
{{#Wiki_filter:ATTACHMENT 6 Holtec International Report No. HI-2115004, Licensing Report for Replacement of the Palisades Region 1 Spent Fuel Pool Storage Racks (Non-Proprietary Version)303 pages follow mmmmE HOLTEC INTERNATIONAL Holtec Center, 555 Lincoln Drive West, Marlton, NJ 08053 Telephone (856) 797- 0900 Fax (856) 797 -0909 LICENSING REPORT FOR REPLACEMENT OF THE PALISADES REGION 1 SPENT FUEL STORAGE RACKS FOR ENTERGY Holtec Report No: HI-2115004 Holtec Project No: 2119 Sponsoring Holtec Division:
NPD Report Class: SAFETY RELATED HOLTEC INTERNATIONAL DOCUMENT NUMBER: 2115004 PROJECT NUMBER: 2119 DOCUMENT ISSUANCE AND REVISION STATUS DOCUMENT NAME: Licensing Report for Replacement of the Palisades Region 1 Spent Fuel Storage Racks DOCUMENT CATEGORY:
[] GENERIC Z PROJECT SPECIFIC REVISION No. 0 REVISION No. 1 REVISION No.No. Document Portiontf Author's Date Author's Date Author's Date VIR #Initials Approved VIk # Initials Approved VIR # Initials Approved 1 Chapt 1 ER 2/1/2012 88225 ER 2/13/2012 604147 2. Chapt 2 ER 2/1/2012 931637 N/A N/A N/A 3. Chapt 3 ER 2/1/2012 938562 N/A N/A N/A 4. Chapt 4 BK 2/8/2012 183272 BK 2/14/2012 849987 5. Chapt 5 ER 2/1/2012 362410 N/A N/A I N/A 6. Chapt 6 HP 2/9/2012 348382 CB 2/14/2012 772310 7. Chapt 7 ZY 2/8/2012 795609 N/A N/A N/A 8. Chapt 8 CB 2/8/2012 141320 CB 2/13/2012 714083 Chapt HF 2/9/2012 345670 HF 2/13/2012 537354 9 9 10. Chapt ER 2/1/2012 494179 ER 2/13/2012 291660 11.12.13.14.15.tt Chapter or section number.Form Last Revised 7/22/11 Pagel of2 Holtee Form QA- 18 HOLTEC INTERNATIONAL DOCUMENT NUMBER: 2115004 PROJECT NUMBER: 2119 DOCUMENT CATEGORIZATION In accordance with the Holtec Quality Assurance Manual and associated Holtec Quality Procedures (HQPs), this document is categorized as a: R- Calculation Package 3 (Per HQP 3.2) Z Technical Report (Per HQP 3.2)(Such as a Licensing Report)-' Design Criterion Document (Per HQP 3.4) E] Design Specification (Per HQP 3.4)-- Other (Specify):
DOCUMENT FORMATTING The formatting of the contents of this document is in accordance with the instructions of HQP 3.2 or 3.4 except as noted below: DECLARATION OF PROPRIETARY STATUS Z Nonproprietary
-- Holtec Proprietary E] Privileged Intellectual Property (PIP)Documents labeled Privileged Intellectual Property contain extremely valuable intellectual/commercial property of Holtec International.
They cannot be released to external organizations or entities without explicit approval of a company corporate officer. The recipient of Holtec's proprietary or Top Secret document bears full and undivided responsibility to safeguard it against loss or duplication.
Notes: 1. This document has been subjected to review, verification and approval process set forth in the Holtec Quality Assurance Procedures Manual. Password controlled signatures of.Holtec personnel who participated in the preparation, review, and QA validation of this document are saved in the N-drive of the company's network. The Validation Identifier Record (VIR) number is a random number that is generated by the computer after the specific revision of this document has undergone the required review and approval process, and the appropriate Holtec personnel have recorded their password-controlled electronic concurrence to the document.2. A revision to this document will be ordered by the Project Manager and carried out if any of its contents is materially affected during evolution of this project. The determination as to the need for revision will be made by the Project Manager with input from others, as deemed necessary by him.3. Revisions to this document may be made by adding supplements to the document and replacing the "Table of Contents", this page and the "Revision Log".Form Last Revised 7/22/11 Page 2 of 2 Holtec Form QA- 18
 
==SUMMARY==
OF REVISION Revision 1: Incorporated client-suggested editorial corrections and improvements in report Chapters 1, 4, 6, 8, 9 and 10.Holtec Report HI-2115004 Holtec Report HI-2 115004 Holtec Project 2119 i Holtec Project 2119 TABLE OF CONTENTS Section Description Page
 
==1.0 INTRODUCTION==
 
AND REPORT OUTLINE .........................................................
1-1 1.1 Introduction
................................................................................................................
1-1 1.2 Report Outline ............................................................................................................
1-4 1.3 References
..................................................................................................................
1-5 2.0 FUEL STORAGE RACKS DESIGN, DESIGN CRITERIA AND CODES& STANDARDS TO MEET SAFETY REQUIREMENTS
.....................................
2-1 2.1 Introduction
................................................................................................................
2-1 2.2 Sum m ary of Principal D esign Criteria .......................................................................
2-4 2.3 A pplicable Codes and Standards
...............................................................................
2-5 2.4 Quality A ssurance Program .......................................................................................
2-9 2.5 M echanical D esign ...................................................................................................
2-10 2.6 Rack Fabrication
.....................................................................................................
2-12 3.0 M A TERIA L CON SID ERA TION S ............................................................................
3-1 3.1 Introduction
................................................................................................................
3-1-3.2 Structural M aterials ....................................................................................................
3-2 3.3 N eutron Absorbing M aterial ......................................................................................
3-3 3.4 In-Service Surveillance of the N eutron A bsorber ......................................................
3-8 3.5 References................................................................................................................
3-13 4.0 CRITICA LITY CON SID ERA TION S .......................................................................
4-1 4.1 Introduction
.............
...............................
4-1 4.2 M ethodology
.......................................................................................
: .............
....... 4-4 4.3 Acceptance Criteria .........................................
4-58 4.4 A ssum ptions ........................................................................................................
4-59 4.5 Input D ata ...............................................................................................................
4-61 4.6 A nalysis ....................................................................................................................
4-78 4.7 Conclusion
..............................................
4-117 4.8 References
............................................................................................................
4-118 Holtec Report HI-2 115004 ii Holtec Project 2119 Holtec Report HI-2115004 ii Holtec Project 2119 TABLE OF CONTENTS (continued)
Section Description Pae 5.0 THERMAL-HYDRAULIC EVALUATION
.............................................................
5-1 5 .1 Introdu ctio n ................................................................................................................
5-1 5.2 A cceptance C riteria ...................................................................................................
5-4 5.3 Description of Spent Fuel Pool Cooling System .......................................................
5-5 5.4 Assumptions and Design Data ...................................................................................
5-7 5.5 Heat Loads and Bulk Pool Temperatures
.................................................................
5-12 5.6 Local W ater and Fuel Cladding Temperatures
........................................................
5-22 5 .7 R eferences
................................................................................................................
5-29 6.0 STRUCTURAL/SEISMIC CONSIDERATIONS
.....................................................
6-1 6 .1 In tro du ction ................................................................................................................
6 -1 6.2 Acceptance Criteria Applicable to the Fuel Racks and their Contents ......................
6-3 6.3 Acceptance Criteria for the Bearing Pads ................................................................
6-10 6.4 Dynamic Analysis Methodology
..............................................................................
6-11 6.5 Key Input Data for Dynamic Analysis .....................................................................
6-19 6.6 Dynamic Simulations for the Palisades SFP ............................................................
6-22 6.7 Compliance with the Acceptance Criteria Under the Seismic Loads ......................
6-25 6.8 Evaluation of Steady-State Conditions
....................................................................
6-33 6.9 Qualification of the Bearing Pad and Bearing Pressure on the Pool Slab ....... 6-36 6 .10 R eferen ces ................................................................................................................
6-3 8 7.0 CONSIDERATIONS OF MECHANICAL ACCIDENTS
........................................
7-1 7 .1 In tro du ction ................................................................................................................
7-1 7.2 Applicable Mechanical Accidents and Acceptance Criteria ......................................
7-1 7.3 Computer Code and Key Input Data ..........................................................................
7-8 7 .4 A n aly sis ....................................................................................................................
7 -1 1 7 .5 C on clu sion ...............................................................................................................
7 -2 4 7 .6 R eferen ces ................................................................................................................
7-2 5 8.0 SAFETY CONSIDERATIONS FOR THE SFP WATER RETENTION BOUNDARY .... ...............................................
8-1 8 .1 S co p e ..........................................................................................................................
8 -1 8.2 Reinforced Concrete Pool Structure
...................................
8-2 8 .3 P o o l L in er ...................................................................................................................
8-6 8 .4 R eferen ces ................................................................................................................
8-10 Holtec Report HI-2115004 iii Holtec Project 2119 TABLE OF CONTENTS (continued)
Section Description Page 9.0 RAD IOLO GICA L EVA LU A TION ...........................................................................
9-1 9.1 Introduction
................................................................................................................
9-1 9.2 M ethodology
.............................................................................................................
9-1 9.3 A cceptance Criteria ....................................................................................................
9-1 9.4 A ssum ptions and Operating Param eters ....................................................................
9-3 9.5 Analysis ......................................................................................................................
9-3 9.6 Conclusions
................................................................................................................
9-3 9.7 References
..................................................................................................................
9-4 10.0 IN STA LLA TION .....................................................................................................
10-1 10.1 Introduction
.................................................................................................
...........
.. 10-1 10.2 Rack A rrangem ent ...................................................................................................
10-3 10.3 Rack Interferences
....................................................................................................
10-3 10.4 Rem oval of Existing Racks and Installation of N ew Racks ....................................
10-4 10.5 Safety, H ealth Physics, and A LARA M ethods ........................................................
10-5 10.6 Radw aste M aterial Control ......................................................................................
10-6 Holtec Report HI-2 115004 lv Holtec Project 2119 Holtec Report HI-2115004 iv Holtec Project 2119 LIST OF TABLES Table Description Page 2.1.1 Geometric and Physical Data for New SFP Storage Racks .......................................
2-2 2.5.1 Module Data for New Spent Fuel Storage Racks ....................................................
2-11 3.3.1 Previous and In-Process Spent Fuel Storage Equipment with MetamicTM
............
3-7 3.4.1 Recommended Coupon Measurement Schedule ......................................................
3-12 4.2. 1(a) Summary of the Area of Applicability of the MCNP5-1.51 Benchmark
.................
4-36 4.2.1 (b) Analysis of the Unborated and Borated Water for the MCNP5-1.51 C alcu lation s ..............................................................................................................
4 -3 7 4.2.1 (c) Bias and Bias Uncertainty as a Function of Independent Parameter for SFP Racks Filled with Un-Borated (Fresh) W ater .........................................................
.4.38 4.2.1 (d) The Bias and Bias Uncertainty for SFP Racks Filled with Pure Water ..............
4-39 4.2.1 (e) The Bias and Bias Uncertainty for SFP Filled with Borated Water .........................
4-40 4.5.1 Fuel A ssem bly Specifications
.................................
....................................
: ............
4-64 4.5.2(a) M ain SFP and North Tilt Pit Param eters .................................................................
4-66 4.5.2(b) M ain SFP and North Tilt Pit Param eters .................................................................
4-67 4.5.3(a) Fuel Rack Parameters and Dimensions, Region 1 ...................................................
4-68 4.5.3(b) Fuel Rack Parameters and Dimension, Region 2 ......................
4-70 4.5.4(a) N on-Fuel M aterial Com positions
............................................................................
4-71 4.5.4(b) N on-Fuel M aterial Com positions
..........................................................................
4-72 4.5.5 Fuel M aterial Com positions
.... .... ...........................
................................
4-73 4.6.1 Results of the MCNP5-1.51 Calculations for the Design Basis Fuel Assembly C alcu lation s ..............................................................................................................
4 -86 4.6.2(a) Results of the MCNP5-1.51 Calculations for the Effect of Water Temperature and D ensity in R egion 1 ..........................................................................................
4-87 4.6.2(b) Results of the MCNP5-1.51 Calculations for the Effect of Water Temperature and Density on Reactivity in Region 2 ..................................
4-88 4.6.3(a) Results of the MCNP5-1.51 Calculations for Fuel Tolerances at Region 1 SFP R acks w ith Pure W ater .............................................................................................
4-89 4.6.3(b) Results of the MCNP5-1.51 Calculations for Fuel Tolerances at Region 1 SFP Racks w ith 1720 ppm Borated W ater.....................................................................
4-90 4.6.4(a) Results of the MCNP5-1.51 Calculations for Rack Tolerances at Region 1 SFP w ith P ure W ater .......................................................................................................
4 -9 1 4.6.4(b) Results of the MCNP5-1.51 Calculations for the Rack Tolerances at Region 1 SFP w ith 1720 ppm B orated W ater .................................................................................
4-92 4.6.5 Results of the MCNP5-1.51 Calculations for the Minimum Water Gap Width B etw een R egion 1 R acks .........................................................................................
4-93 4.6.6 Results of the MCNP5-1.51 Calculations for Eccentric Positioning in R egion 1 S F P ..........................................................................................
I .................
4 -94 Holtec Report HI-21 15004 V Holtec Project 2119 Holtec Report HI-2115004 V Holtec Project 2119 LIST OF TABLES (continued)
Table Description Page 4.6.7(a) Results of the MCNP5-1.51 Calculation Scenario 1 for a 3x3 Array Model, with a Fuel Assembly with Missing 4 Fuel Rods from the Cell in the Center ........ 4-95 4.6.7(b) Results of the MCNP5-1.51 Calculation Scenario 1 for a 3x3 Array Model, with a Fuel Assembly with Missing 4 Fuel Rods from the Cell in the Center ........ 4-96 4.6.7(c) Results of the MCNP5-1.51 Calculation Scenario 2 for aSingle Cell Model, with a Fuel Assembly with Missing 4 Fuel Rods ........................
4-97 4.6.7(d) Results of the MCNP5-1.51 Calculation Scenario 2 for a Single Cell Model, with a Fuel Assembly with M issing 4 Fuel Rods ....................................................
4-98 4.6.8(a) Maximum klff Calculation for Region 1 SFP with Pure Water ................................
4-99 4.6.8(b) Maximum kff Calculation for Region 1 SFP with 850 ppm Borated Water .........
4-100 4.6.9(a) Margin Analysis, Results of the MCNP5-1.51 Calculations to Evaluate the Effect of Using minimum B 4 C Loading and Minimum MetamicTM Panel Thickness, Instead of Nominal Values on Reactivity
....................
4-101 4.6.9(b) Margin Analysis, Results of the MCNP5-1.51 Sensitivity Analysis to Evaluate the Change in SFP Reactivity as a Function of B 4 C Loading ...........................
44102 4.6.10 Results of the MCNP5-1.51 Calculations for the Effect of Two Fuel Assemblies in the Elevator Region on Reactivity of Region 1 Racks.......................................
4-103 4.6.11 Results of the M CNP5-1.51 Interface Calculations
..............................................
4-104 4.6.12(a)
Results of the M CNP5-1.51 Interface Calculations
...............................................
4-105 4.6.12(b)
Results of the MCNP5-1.51 Interface Calculations
....................
...........
4-106 4.6.13 Results of the M CNP5-1.51 Interface Calculations
...............................................
4-107 4.6.14 Results of the MCNP5-1.51 Calculations for the Effect of Increased Water Temperature on Reactivity of SFP with Pure Water .............................................
4-108 4.6.15 Results of the MCNP5-1.51 Calculations for the Effect of Horizontally Dropped Fuel Assembly ................................................
4-109 4.6.16 Results of the MCNP5-1.51 Calculations for the Effect of Vertically Dropped Fuel A ssem bly into a Storage Cell .........................................................................
4-110 4.6.17(a)
Results of the MCNP5-1.51 Calculations for the Effect of Mislocated Fuel Assembly in Elevator Region (Mislocated Fuel Assembly in the Comer of the E levator R egion) ....................................................................................................
4-111 4.6.17(b)
Results of the MCNP5-1.51 Calculations for the Effect of Mislocated Fuel Assembly in Elevator Region (Mislocated Fuel Assembly at the South of Inspection Station) .....................................................................
........ 4-112 4.6.18(a)
Results of the MCNP5-1.51 Calculations for the Effect of Mislocated Fuel Assembly in North Tilt Pit (Mislocated Fuel Assembly Rods are Lined Up with Fuel R ods in R egion 1 R ack) .............................................................
-..................
4-113 4.6.18(b)
Results of the MCNP5-1.51 Calculations for the Effect of Mislocated Fuel Assembly in North Tilt Pit (Mislocated Fuel Assembly Rods are Lined Up with Fuel R ods in Region 2 R ack) ........................................
.................................
4-114 Holtec Report HI-2115004 vi Holtec Project 2119 LIST OF TABLES (continued)
Table Description Page 4.6.19 Results of the MCNP5-1.51 Calculations for the Effect of Region 1 Rack M ov em ent ..............................................................................................................
4 -115 4.6.20 Maximum kff Calculation for Region 1 SFP Filled with 1350 ppm Borated W ater During A ccident Condition
.........................................................................
4-116 5.1.1 Partial Listing of Rerack Applications Using Similar Methods of Therm al-H ydraulic A nalysis ......................................................................................
5-3 5.3.1 SFP Cooling System Design Performance Data ........................................................
5-6 5.4.1 Summary of Inputs for Bulk Temperature Analysis ................................................
5-10 5.4.2 Summary of Inputs for Local Temperature Analysis ...............................................
5-11 5.5.1 Summ ary of Bulk Temperature Results ..................................................................
5-16 5.5.2 Sum m ary of Tim e-to-Boil Results ...........................................................................
5-17 5.6.1 Sum m ary of Local Temperature Results ..................................................................
5-26 6.4.1 Partial Listing of Fuel Rack Applications Using DYNARACK ..............................
6-41 6.4.2 D egrees-of-Freedom
.................................................................................................
6-42 6.5.1 Rack Material Data (200F) ........ .........
......................
6-43 6.6.1 Maximum Values of Stress Factors and Impact Loads ............................................
6-44 6.6.2 Maximum Values of Lateral Displacements
............................................................
6-45 7.3.1 K ey In put D ata ..........................................................................................................
7-9 7.3.2 M aterial Properties
...................................................................................................
7-10 7.4.1 Impact Event Data ..............................................
7-15 7.4.2 Strain Rate Amplification Curve for Base Metal Material ......................................
7-16 7.4.3 R esults for Shallow D rop .........................................................................................
7-17 7.4.4 Results for Deep Drop Scenario 1 (Away From Support Pedestal)
.........................
7-18 7.4.5 Results for Deep Drop Scenario 2 (Above Support Pedestal)
................
7-19 8.2.1 Key Dim ensions of Palisades Storage Pools ..............................................................
8-4 8.2.2 Dead and Seismic Loads from Region 1 Rack Modules ...........................................
8-5.8.3.1 Key Input Data for SFP Liner Evaluation
...............................
8-8 8.3.2 R esults of SFP Liner Evaluation
................................................................................
8-9 9.3.1 Fuel Handling Accident Acceptance Criteria..............................
9-2 Holtec Report HI-2115004 vii Holtec Project 2119 LIST OF FIGURES Figure Description Page 1.1.1 Proposed Layout for New Region 1 Fuel Storage Racks ...........................................
1-3 2.1.1 Isom etric View of a Generic Flux Trap Rack ..........................................................
2-3 2.6.1 Isometric View of Composite Box Assembly ..........................................................
2-15 2.6.2 Isometric View of Flux Trap Rack Cell Lead-In .....................................................
2-16 2.6.3 Connection of Composite Box Assemblies
.............................................................
2-17 2.6.4 Flux Trap Rack Cells Elevation V iew .....................................................................
2-18 2.6.5 A djustable Pedestal D esign ......................................................................................
2-19 4.1.1 The SFP and Tilt Pit Layout of Palisades
..................................................................
4-3 4.2.1 A 2-D Representation of the MCNP5-1.51 Region 1 Racks Eccentric Fuel Positioning Model (2x2 cells toward outside model) ..............................................
4-41 4.2.2 A 2-D Representation of the MCNP5-1.51 Region 1 Racks Eccentric Fuel Positioning Model (2x2 cells toward center model) ................................................
4-42 4.2.3 A 2-D Representation of the MCNP5-1.51 Region 1 Racks Eccentric Fuel P ositioning M odel ....................................................................................................
4-43 4.2.4 A 2-D Representation of the MCNP5-1.51 Region 1 Racks with Missing Four F u el R o d s .................................................................................................................
4 -4 4 4.2.5 A 2-D Representation of the MCNP5-1.51 Model of Two Fuel Assemblies in the E levator R egion .............................................................................................
4-45 4.2.6 A 2-D Representation of the MCNP5-1.51 Model of Regionl Rack with the Minimum Rack to Rack Width Distance ................................
4-46 4.2.7 A 2-D Representation of the MCNP5-1.51 Model ..................................................
4-47 4.2.8 A 2-D Representation of the MCNP5-1.51 Model of Region 1, 7.5x19 Array ....... 4-48 4.2.9 A 2-D Representation of the MCNP5-1.51 Model of Region 2, 7.5x19 Array ........ 4-49 4.2.10 A 2-D Representation of the MCNP5-1.51 Model of Interface for Calculating the Effect of Region 1 Rack on Region 2 Rack Reactivity
............................................
4-50 4.2.11 A 2-D Representation of the MCNP5-1.51 Model of Interface
..............................
4-51 4.2.12 2-D Representation of the MCNP5-1.51 Model of Horizontally Dropped.Fuel Assembly on Top of the Region1 Racks ..................................................................
4-52 4.2.13 2-D Representation of the MCNP5-1.51 Model of Vertically Dropped Fuel.A ssem bly ..................................................................................................................
4-53 4.2.14 A 2-D Representation of the MCNP5-1.51 Model of Mislocated Fuel Assembly in Com er of the Elevator R egion .............................................................................
4-54 4.2.15 A 2-D Representation of the MCNP5-1.51 Model of Mislocated Fuel Assembly in the Elevator Region, South of the Inspection Station ..........................................
4-55 4.2.16 2-D Representations of the MCNP5-1.51 Model of Mislocated Fuel Assembly in the N orth T ilt P it ..................................................................................................
4-56 4.2.17 A 2-D Representation of the MCNP5-1.51 Model of Part of Region 1 Rack .M o v em en t ................................................................................................................
4 -57 Holtec Report HI-2115004 viii Holtec Project 2119--- -1[--,J LIST OF FIGURES (continued)
Fibgre Description I Page 4.5.1 A 2-D Representation of the MCNP5-1.51 Model of the Regioni SFP Racks ....... 4-74 4.5.2 A 2-D Axial Representation of the Regioni Rack MCNP5-1.51 Model .................
4-75 4.5.3 A Partial 2-D Representation of Neutron Absorber Location ..................................
4-76 4.5.4 A 2-D Representation of the MCNP5-1.51 Region 2 Rack Model ...........
4-77 5.5.1 Recently Offloaded Fuel Decay Heat versus Time ..................................................
5-18 5.5.2 Sim plified Heat Exchanger Alignm ent ....................................................................
5-19 5.5.3 Bulk Temperature and Decay Heat Load versus Time -Refueling Batch Offload S cen ario 1 .................................................................................................................
5 -2 0 5.5.4 Bulk Temperature and Decay Heat Load versus Time -Full Core Offload S cenario 2 ................................................................................................................
5-2 1 5.6.1 Contours of Static Temperature in a Vertical Plane through the Center of the M ain SF P .......................................................................................................
5-27 5.6.2 Contours of Static Temperature in a Vertical Plane through the Center of the N orth T ilt P it ..................................................................................................
5-28 6.4.1 Single R ack D ynam ic M odel ...................................................................................
6-46 6.4.2 Fuel-To-Rack Im pact Springs ..................................................................................
6-47 6.4.3 2-D Schematic Elevation of the Storage Rack Model .............................................
6-48 6.4.4 Rack Degrees of Freedom and Modeling Technique
...............................................
6-49 6.4.5 2-D Inter-R ack Im pact Springs ................................................................................
6-50 6.5.1 Generated Acceleration Time History in E-W Direction, Sets I to 5 ......................
6-51 6.5.2 Target and Generated Response Spectra in E-W Direction, Sets I to 5 .................
6-52 6.5.3 Target and Average of Generated Response Spectra in E-W Direction
..................
6-53 6.5.4 Target and Average of Regenerated PSD in E-W Direction
....................................
6-53 6.5.5 Generated Acceleration Time History in N-S Direction, Sets 1 to 5 .......................
6-54 6.5.6 Target and Generated Response Spectra in N-S Direction, Sets 1 to 5 ...................
6-55 6.5.7 Target and Average of Generated Response Spectra in N-S Direction
...................
6-56 6.5.8 Target and Average of Generated PSD in N-S Direction
........................................
6-56 6.5.9 Generated Acceleration Time History in Vertical Direction, Sets 1 to 5 .................
6-57 6.5.10 Target and Generated Response Spectra in Vertical Direction, Sets I to 5 .............
6-58 6.5.11 Target and Average of Generated Response Spectra in Vertical Direction
.............
6-59 6.5.12 Target and Average of Generated PSD in Vertical Direction
..................................
6-59 6.6.1 Limiting Interim Rack Storage Configuration during Installation Sequence ...........
6-60 7.2.1 Schem atic of Shallow D rop Event ...........................................................................
7-5 7.2.2 Schematic of Deep Drop Event Away From a Support Pedestal .............................
7-6 7.2.3 Schematic of Deep Drop Event Above a Support Pedestal .....................................
7-7 7.4.1 Plastic Strain and Deformation from Shallow Drop Event ................
7-20 Holtec Report HI-2115004 ix Holtec Project 2119 LIST OF FIGURES (continued) 7.4.2 7.4.3 7.4.4 8.3.1 Baseplate Deformation from Deep Drop Event (Away From Support Pedestal)
.... 7-21 Floor Impact Force Time History from Deep Drop Event (Above Support P ed estal) ...................................................................................................................
7 -2 2 Plastic Strain of the Floor Liner from Deep Drop Event (Above Support P ed estal) ...................................................................................................................
7 -2 3 Finite Element Model of SFP Liner Section .......................................................
8-11 Holtec Report HI-2115004 X Holtec Project 2119 CHAPTER 1: INTRODUCTION AND REPORT OUTLINE 1.1 Introduction The Palisades Nuclear Plant (PNP or Palisades) is a pressurized-water reactor (PWR) nuclear power plant equipped with a spent fuel pool (SFP) for storage of new and used fuel assemblies.
Some of the SFP racks are equipped with a boron carbide neutron absorber material, Carborundum, that is exhibiting degradation.
Entergy intends to replace all such racks with new state-of-the-art racks of a proven design. The new SFP racks will be equipped with the non-degrading neutron absorber material MetamicTM.
This report provides a description of a proposed modification to the SFP rack configuration and a summary of the evaluations performed to support this change.The existing SFP at Palisades includes SFP storage racks in two water-filled sections of the pool inside the plant Auxiliary Building.
The first section is the main SFP, which is a rectangular, reinforced-concrete pool with a stainless-steel liner. This main pool contains storage racks, six of which contain degraded Carborundum that will be replaced with new racks having the same numbers of cells per rack and essentially the same external dimensions.
The second section of the pool is the North Tilt Pit, which is also a rectangular, reinforced-concrete pool with a stainless-steel liner. The two pool sections are hydraulically connected by a partial-height slot.The North Tilt Pit contains three storage racks, of which one contains degraded Carborundum.
This rack will be replaced with a new rack having the same number of cells.All racks to be replaced are Region 1 SFP racks, and are flux trap racks suitable for storing both irradiated and/or un-irradiated fuel assemblies (i.e., do not rely on fuel burnup for reactivity compliance).
The new racks will also be Region 1 racks and will be flux trap racks suitable for storing both irradiated and/or un-irradiated fuel assemblies.
The other racks, Region 2 racks, are racks without flux traps that require fuel assemblies stored therein to possess a sufficient minimum burnup. Figure 1.1.1 shows the proposed configuration of the new SFP storage racks.All new SFP storage racks will be freestanding and self-supporting.
The principal construction materials for the racks will be SA240-304L stainless steel sheet and plate stock, and SA564-630 Holtec Report HI- 2115004 1-1 Holtec Project 2119 precipitation hardened stainless steel bar for the adjustable support pedestals.
The only non-stainless material utilized in the racks will be the neutron absorber material, which is a patented boron carbide and aluminum metal matrix composite available under the product name MetamicTM.
All of the new SFP storage racks have been designed to meet the stress limits of, and to be analyzed in accordance with, Section III, Division 1, Subsection NF of the ASME Boiler and Pressure Vessel (B&PV) Code [1.1.1]. The material procurement, analysis, and fabrication of the rack modules will conform to USNRC 1 OCFR50 Appendix B requirements
[ 1.1.2].The rack designs described herein are direct evolutions of other previous licensee applications.
The operational and performance criteria specified for the racks are intended to ensure that the racks will meet all governing requirements of the applicable codes and standards and, in particular, the "OT Position for Review and Acceptance of Spent Fuel Storage and Handling Applications," USNRC (1978) and 1979 Addendum thereto [1.1.3].Holtec Report HI- 2115004 1-2 Holtec Project 2119 Holtec Report HI- 2115004 1-2 Holtec Project 2119 FIGURE 1.1.1 -PROPOSED LAYOUT FOR NEW REGION 1 FUEL STORAGE RACKS (For Reference Only -All Dimensions Approximate
-Region 2 Racks in Phantom)Holtec Report HI- 2115004 1-3 Holtec Project 2119 1.2 Report Outline The individual chapters of this report present the following information:
Chapters 2 and 3 of this report provide an abstract of the racks design and information about the materials that will be used for construction of the racks, respectively.
Chapter 4 provides a summary of the criticality safety evaluation of the SFP storage racks.Chapter 5 provides a summary of the thermal-hydraulic evaluation of the SFP storage racks.Chapter 6 provides a summary of the seismic/structural considerations of the SFP storage racks.Chapter 7 provides a summary of the mechanical accident considerations of the SFP storage racks.Chapter 8 provides a summary of the safety considerations of the reinforced-concrete pool structure and the stainless-steel liner plates.Chapter 9.provides a summary of the radiological evaluation of the SFP storage racks.* Chapter 10 provides a summary of the approach to installation that will be implemented for the SFP storage racks.Holtec Report HI- 2115004 1-4 Holtec Project 2119 Holtec Report HI- 2115004 1-4 Holtec Project 2119
 
===1.3 References===
[1.1.1] American Society of Mechanical Engineers (ASME), Boiler & Pressure Vessel Code, Section III, Subsection NF, 1998 Edition.[1.1.2] Code of Federal Regulations (CFR), Title 10, Appendix B, "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants".[1.1.3] USNRC, "OT Position for Review and Acceptance of Spent Fuel Storage and Handling Applications," April 14, 1978, and Addendum dated January 18, 1979.Holtec Report HI- 2115004 1-5 Holtec Project 2119 CHAPTER 2:FUEL STORAGE RACKS DESIGN, DESIGN CRITERIA AND CODES & STANDARDS TO MEET SAFETY REQUIREMENTS
 
===2.1 Introduction===
Region 1 of the main SFP and the North Tilt Pit will be equipped, respectively, with six and one safety-related, Seismic Category I, fuel storage racks with a total storage capacity of 422 fresh and/or spent fuel assemblies.
All new fuel storage racks will be freestanding modules, made primarily from Type 304L austenitic stainless steel, containing honeycomb storage cells for optimal structural strength.
As described in Chapter 1, all new racks are Region 1 racks and have a flux trap, bounded by two panels of MetamicTM metal matrix composite containing a high areal loading of Boron-10 (B-10) isotope, between adjacent fuel assemblies.
Region 1 racks can safely store either new or spent fuel assemblies.
Figure 2.1.1 provides an isometric schematic of a typical flux trap design storage rack module. Data on the cross sectional dimensions, weight and cell count for each rack module is presented in Table 2.1 .1.The baseplates on the fuel storage rack modules extend out beyond the rack module periphery walls such that the baseplate protrusions act to set a required minimum separation between the facing cells of any adjacent rack modules. Each SFP storage rack module is supported by multiple pedestals, which are remotely adjustable.
The rack module support pedestals length adjustment is primarily provided to accommodate minor level variations in the floor flatness.Thus, the racks can be made vertical and the top of adjacent racks can easily be made co-planar with each other.The overall design of the SFP storage rack modules is similar to those presently in service in the spent fuel pools at numerous other nuclear plants. Altogether, Holtec has provided thousands of storage cells of this design to various nuclear plants around the world.Holtec Report HI-2115004 2-1 Holtec Project 2119 TABLE 2.1.1 GEOMETRIC AND PHYSICAL DATA FOR NEW SFP STORAGE RACKS RACK NO. OF CELLS MODULE ENVELOPE SIZE BOUNDING NO. OF CELLS PER LOCATION I.D. N-S E-W N-S E-W WEIGHT (LB) RACK NI SFP 8 8 80.68 80.68 18,000 64 N2 SFP 8 8 80.68 80.68 18,000 64 N3 SFP 8 8 80.68 80.68 18,000 64 N4 SFP 8 8 80.68 80.68 18,000 64 N5 SFP 8 8 80.68 80.68 18,000 60 N6 SFP 8 8 80.68 80.68 16,000 56 N7 North Tilt Pit 10 5 101.18 49.93 15,000 50 Note: All dimensions in this table are approximate nominal values. The weights in this table include a built-in margin to account for thickness overages in procured plate and sheet stock and for weld filler material, as well as to maximize the inertia loads under earthquakes analyzed and discussed in Chapter 6.Holtec Report HI-21 15004 2-2 Holtec Project 2119 Holtec Report HI-2115004 2-2 Holtec Project 2119 FIGURE 2.1.1 -ISOMETRIC VIEW OF A GENERIC FLUX TRAP RACK Holtec Report HI-2115004 2-3 Holtec Project 2119 2.2 Summary of Principal Design Criteria The key design criteria for the new SFP storage racks are set forth in the USNRC memorandum entitled "OT Position for Review and Acceptance of Spent Fuel Storage and Handling Applications," dated April 14, 1978, as modified by amendment dated January 18, 1979. The individual sections of this report expound on the specific design bases derived from the above-mentioned "OT Position Paper." A brief summary of the design bases for the racks is presented in the following:
: a. Disposition:
All rack modules are required to be freestanding to minimize stresses in the racks and the pool structure induced by differential thermal expansion.
: b. Kinematic Stability:
All freestanding modules must be kinematically stable (against tipping or overturning) under the postulated Safe Shutdown Earthquake (SSE) event for the plant.c. Structural Compliance:
All primary stresses in the rack modules must satisfy the limits for linear structures in Section III, Subsection NF, of the ASME B&PV Code.d. Thermal-Hydraulic Compliance:
The integrated average (i.e., bulk) pool temperature is required to remain below 1507F following any normal offload, either partial core or full core, including the effects of a worst-case single active component failure. The bulk pool temperature is required to remain below boiling subsequent to any abnormal offload without any coincident cooling system failures.e. Criticality Compliance:
The fuel storage racks must be able to store fuel of 5.0 weight percent (wt%) maximum enrichment while maintaining the reactivity (keff) less than 0.95.f. Accident Events: In the event of postulated drop events (uncontrolled lowering of a fuel assembly, for instance), it is necessary to demonstrate that the subcritical geometry of the rack structure is not compromised.
The foregoing design bases are further articulated in the subsequent chapters of this report.Holtec Report HI-2115004 2-4 Holtec Project 2119 2.3 Applicable Codes and Standards The following codes, standards and practices are used, as applicable, for the design, construction, and assembly of the fuel storage racks. The latest revisions of all document s listed herein are utilized, unless otherwise stated below. Additional specific references related to detailed analyses are given in each section.a. Design Codes (1) American National Standards Institute/
American Nuclear Society ANSI/ANS 57.1-1992, "Design Requirements for Light Water Reactor Fuel Handling Systems." (2) American National Standards Institute/
American Nuclear Society ANSI/ANS 57.2-1983, "Design Requirements for Light Water Reactor, Spent Fuel Storage Facilitiesat Nuclear Power Plants".(3) American National Standards Institute/
American Nuclear Society ANSI/ANS 57.3-1983, "Design Requirements for New Fuel Storage Facilities at Light Water Reactor Plants." (4) ASME B&PV Code Section Iii, Subsection NF, 1998.(5) American Society for Nondestructive Testing SNT-TC-1A, "Recommended Practice for Personnel Qualifications and Certification in Nondestructive Testing".(6) ASME B&PV Code, Section II, latest edition.b. Standards of American Society for Testing and Materials (ASTM)(1) ASTM A262-02a -Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steel.(2) ASTM C750 -Standard Specification for Nuclear-Grade Boron Carbide Powder.c. Welding Codes (1) ASME B&PV Code, Section IX -Welding and Brazing Qualifications, latest edition.d. Quality Assurance, Cleanliness, Packaging, Shipping, Receiving, Storage, and Handling (1) ASME B&PV Code, Section V, Nondestructive Examination, latest edition.Holtec Report HI-2115004H 2-5 Holtec Project 2119 (2) ASME NQA- 1 -Quality Assurance Program Requirements for Nuclear Facilities.
: e. USNRC Standard Review Documents (1) NRC Generic Letter 78-011, "OT Position for Review and Acceptance of Spent Fuel Storage and Handling Applications," dated April 14, 1978, and the modifications to this document of January 18, 1979.(2) Standard Review Plan (SRP) Section 3.7, Seismic Design.(3) Standard Review Plan (SRP) Section 3.8.4, Other Seismic Category I Structures, Appendix D, Technical Position on Spent Fuel Racks.(4) Standard Review Plan (SRP) Section 9.1.1, Criticality Safety of Fresh and Spent Fuel Storage and Handling.(5) Standard Review Plan (SRP) Section 9.1.2, New and Spent Fuel Storage.(6) Standard Review Plan (SRP) Section 9.1.3, Spent Fuel Pool Cooling and Cleanup System.f. ANSI Standards (1) ANSI/ANS 8.1-1998(2007)
-Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors.(2) ANSI/ANS 8.17-2004
-Criticality Safety Criteria for the Handling, Storage, and Transportation of LWR Fuel Outside Reactors.(3) ANSI/ANS 16.9-75 -Validation of Calculation Methods for Nuclear Criticality Safety.g. Code-of-Federal Regulations (CFR)(1) 10CFR20 -Standards for Protection Against Radiation.
(2) 1OCFR21 -Reporting of Defects and Non-compliance.
(3) 10CFR50 Appendix A -General Design Criteria for Nuclear Power Plants, General Design Criteria 2, 61 and 62.(4) 1 OCFR50 Appendix B -Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.(5) 10CFR50, Section 68 -Criticality Accident Requirements.
Holtec Report HI-2115004 2-6 Holtec Project 2119
: h. USNRC Regulatory Guides (RG)(1) RG 1.13 -Spent Fuel Storage Facility Design Basis.(2) RG 1.25 -Assumptions Used for Evaluating the Potential Radiological Consequences of a Fuel Handling Accident in the Fuel Handling 'and Storage Facility for Boiling and Pressurized Water Reactors.(3) RG 1.28 -Quality Assurance Program Requirements
-Design and Construction.
(4) RG 1.29 -Seismic Design Classification.
(5) RG 1.31 -Control of Ferrite Content in Stainless Steel-Weld Metal.(6) RG 1.44 -Control of the Use of Sensitized Stainless Steel.(7) RG 1.60 -Design Response Spectra for Seismic Design of Nuclear Power Plants.(8) RG 1.61 -Damping Values for Seismic Design of Nuclear Power Plants.(9) RG 1.92 -Combining Modal Responses and Spatial Components in Seismic Response Analysis.(10) RG 1.124 -Service Limits and Loading Combinations for Class 1 Linear-Type Component Supports.(11) RG 3.4 -Nuclear Criticality Safety in Operations with Fissionable Materials at Fuels and Materials Facilities.
: i. American Welding Society (AWS) Standards (1) AWS Dl.1 -Structural Welding Code -Steel.(2) AWS A2.4,- Standard Symbols for Welding, Brazing and Nondestructive Examination.
(3) AWS A3.0 -Standard Welding Terms and Definitions.
(4) AWS A5.12 -Specification for Tungsten and Tungsten Alloy Electrodes for Arc-Welding and Cutting.(5) AWS QC I -Standard for AWS Certification of Welding Inspectors.
(6) AWS 5.4 -Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding.Holtec Report HI-2115004 2-7 Holtec Project 2119 (7) AWS 5.9 -Specification for Bare Stainless Steel Welding Electrodes and Rods.Holtec Report HI-21 15004 2-8 Holtec Project 2119 Holtec Report HI-2115004 2-8 Holtec Project 2119 2.4 Quality Assurance Program The governing quality assurance requirements for design and engineering the new-supply spent fuel storage racks are stated in 1OCFR50 Appendix B. Holtec's Nuclear Quality Assurance program complies with this regulation and is designed to provide a flexible but highly controlled system for the design, analysis and licensing of customized components in accordance with various codes, specifications, and regulatory requirements.
Holtec has been subject to triennial inspections by the USNRC.Holtec Report HI-2115004 2-9 Holtec Project 2119 2.5 Mechanical Design The rack modules are designed as cellular structures such that each fuel assembly has a square opening with conforming lateral support and a flat horizontal-bearing surface. All of the fuel storage locations are constructed with multiple cooling flow holes to ensure that redundant flow paths for the coolant are available.
The basic characteristics of the new SFP storage racks are summarized in Table 2.5.1.A central objective in the design of the new rack modules is to maximize structural strength while minimizing inertial mass and dynamic response.
Accordingly, the rack modules have been designed to simulate multi-flange beam structures resulting in excellent de-tuning characteristics with respect to the applicable seismic events. The next section presents an item-by-item description of the rack modules in the context of the fabrication methodology.
Holtec Report HI-2115004 2-10 Holtec Project 2119 Table 2.5.1 MODULE DATA FOR NEW SPENT FUEL POOL STORAGE RACKS'Storage Cell Inside Dimension 8.75 in.Cell Pitch 10.25 in.Storage Cell Height (above baseplate) 147 3/4 in.Baseplate Hole Size (except for lift locations) 5 1/2 in.Baseplate Thickness I in.Support Pedestal Height (including bearing pads) 12 5/8 Support Pedestal Type Remotely adjustable pedestals Number Of Support Pedestals Per Rack 4 or 5 Number Of Cell Walls Containing Auxiliary Flow 4 Holes At Base Of Cell Wall Remote Lifting And Handling Provisions Yes Neutron Absorber Material MetamicTM Neutron Absorber Length 134 in.Neutron Absorber Width 6 7/8 in.1 All dimensions indicate nominal values.Holtec Report HI-21 15004 2-11 Holtec Project 2119 Holtec Report HI-2115004 2-11 Holtec Project 2119 -
2.6 Rack Fabrication The design of the modules is intended to meet the following objectives:
: 1. The rack modules will be fabricated in such a manner that the storage cell surfaces that would come in contact with the fuel assembly will be free of harmful chemicals and projections (e.g., weld splatter).
: 2. The component connection sequence and welding processes will be selected to reduce fabrication distortions.
: 3. The fabrication process will involve operational sequences that permit immediate accessibility for verification by the inspection staff.4. The racks will be fabricated per the Holtec IOCFR50 Appendix B Quality Assurance program, which ensures, and documents, that the fabricated rack modules will meet all of the requirements of the design and fabrication documents based on the safety analyses documented in this report.This section describes the constituent elements of the flux trap rack module in the fabrication sequence.
Figure 2.1.1 provides a schematic view of a typical flux trap rack. The rack is constructed with water flux traps located between adjacent panels of neutron absorbing material.The rack module manufacturing begins with fabrication of the "box". The boxes are fabricated from two precision formed channels by seam welding in a machine equipped with copper chill bars and pneumatic clamps to minimize distortion due to welding heat input. Figure 2.6.1 shows a typical box. The target minimum weld seam penetration is 80% of the box metal gauge (13 gauge).Holtec Report HI-21 15004 2-12 Holtec Project 2119 Holtec Report Hl-2115004 2-12 Holtec Project 2119 A die is used to flare out one end of the box to provide the tapered lead-in (Figure 2.6.2). Flow holes are made on all four sides near the other end of the box to provide the requisite auxiliary flow holes.Each box constitutes a storage location.
The four external faces of each box are each equipped with a stainless steel sheathing, which holds a MetamicTM sheet (neutron absorber material).
The..MetamicTM is attached snugly to the box surface. This is accomplished by die forming sheathings, as shown in Figure 2.6.1. The flanges of the sheathing are attached to the box using stitch welds and spot welds. The sheathings serve to locate and position the neutron absorber sheet accurately, and to preclude its movement under seismic conditions.
Having fabricated the required number of composite box assemblies, they are joined together in a fixture using connector elements in the manner shown in Figure 2.6.3. Figure 2.6.4 shows an elevation view of two storage cells of the flux trap rack module. Joining the cells by the connector elements results in a well-defined shear flow path, and essentially makes the box assemblage into a multi-flanged beam-type structure.
The "baseplate" is attached to the bottom edge of the boxes. The baseplate is an austenitic stainless steel plate that has large diameter holes (except at lift locations that have irregular shaped cut-outs of similar area) cut out in a pitch identical to the box pitch. The baseplate is attached to the cell assemblage by fillet welding the box edge to the plate.In the final step, adjustable leg supports (shown in Figure 2.6.5) are welded to the underside of the baseplate.
The adjustable legs provide for vertical height adjustment at each leg location.
The top (internal threaded) portion is made of austenitic steel material.
The bottom (external threaded) part is made of 17-4 precipitation-hardened stainless steel to avoid galling. Each support leg is equipped with a readily accessible socket to enable remote leveling of the rack during installation.
Appropriate NDE (nondestructive examination) occurs on all welds including visual examination of sheathing welds, box longitudinal seam welds, box-to-baseplate welds, and box-to-box Holtec Report HI-2115004 2-13 Holtec Project 2119 connection welds, as well as liquid penetrant examination of support leg welds, in accordance with the design drawings.iloltec Report HI-2 115004 2-14 Holtec Project 2119 Holtec Report HI-2115004 2-14 Holtec Project 2119 0 a 0 a 0 (J~0 0 CELL WALLý0 CD a 0 ,o.a o-t CD H AND SMOOTHED ENDS FIGURE 2.6.2 -ISOMETRIC VIEW OF FLUX TRAP RACK CELL LEAD-IN Holtec Report HI-2115004 2-16 'Holtec Project 2119 CD 0ýtd 0I 0©S WATER GAP PLATE 0 z-3-0 0 CD,>,o r o /LAYOUT PITCH p i
* I Fill r I Ii I II I* I I h~1* I I I'I I~~~~*1-4 r7T* S* I I I I I I I I I I I I I 14.*1* I* I I I SI I II I II I I j I S I IPxw SImTFDI/INil"-00001MTHIMIG
-'-Z FMN HOLE (AWULAR)-.I .-r II I I I -UAWC MmL`\ ASEPLATE HOLE FIGURE 2.6.4 -FLUX TRAP RACK CELLS ELEVATION VIEW Holtec Report HI-2 115004 2-18 Holtec Project 2119 Holtec Report HI-2115004 2-18 Holtec Project 2119 I LEVEUNG TOOL SOCKET CELL Y,-IIIIS EPLATE I I M- r I I I ! I I -i 7 lP"'~'-DRJNHOLE TYPICAL ELEVAlON VIEW FIGURE 2.6.5 -ADJUSTABLE PEDESTAL DESIGN Holtec Report 111-2115004 2-19 Holtec Project 2119 Holtec Report Hl-2115004 2-19 Holtec Project 2119 CHAPTER 3: MATERIAL CONSIDERATIONS
 
===3.1 Introduction===
The environment around the spent fuel racks at Palisades is summarized as follows: a. Deep submergence in borated water b. Pool water bulk temperature in the range of 80'F to 150'F under normal storage conditions
: c. Local water temperature around the fuel rods may approach 200'F d. Low Reynolds number water flow through and around the racks e. Relatively low gamma dose rate compared to in-reactor conditions
: f. Negligible neutron fluence In this chapter, the materials selected for use in the fuel racks are shown to possess the necessary characteristics to ensure a long service life without suffering degradation from aging.Holtec Report HI- 2115004 3-1 Holtec Project 2119 3.2 Structural Materials The following structural materials will be utilized in the fabrication of the fuel storage racks: a. Sheet Stock (cells and sheathing):
ASME SA240-304L
: b. Plate Stock (baseplates and internally-threaded support pedestals):
ASME SA240-304L c. Bar Stock (externally-threaded support pedestals):
ASME SA564-630 (heat treated to 1100'F)d. Weld Material:
ASME Type 308L The above materials have been widely used in spent fuel racks for the past three decades without any report of degradation.
Holtec Report HI- 2115004 3-2 Holtec Project 2119 3.3 Neutron Absorbing Material The MetamicTM neutron absorber material, proposed for use in the new SFP storage racks, is manufactured by Holtec's Nanotec Metals Division in Lakeland, Florida. As discussed below, Metamic has been subjected to rigorous tests by various organizations including Holtec International, and has been approved by the USNRC in recent dry as well as wet storage applications.
Holtec has supplied (or is in the process of supplying) spent fuel storage equipment licensed and manufactured with MetamicTM for dozens of previous projects.
Recent U.S. plants using Holtec Metamic-equipped SFP storage racks or in-rack neutron absorber inserts are listed in Table 3.3.1.MetamicTM was developed in the mid-1990s by the Reynolds Metals Company [3.3.1] with the technical support of the Electric Power Research Institute (EPRI) for spent fuel reactivity control in dry and wet storage applications with the explicit objective to eliminate the performance frailties of aluminum cermet type of absorbers reported in the industry.
Metallurgically, MetamicTM is a metal matrix composite (MMC) consisting of a matrix of aluminum reinforced with ASTM C-750 boron carbide. MetamicTM is characterized by extremely fine aluminum (325 mesh or smaller) and boron carbide (B 4 C) powder. Typically, the average B 4 C particle size is between 10 and 40 microns. The high performance and reliability of MetamicTM derives from the fineness of the B 4 C particle size and uniformity of its distribution, which is solidified into a metal matrix composite structure by the powder metallurgy process. This yields excellent homogeneity and a porosity-free material.In the MetamicTM manufacturing process, the aluminum and boron carbide powders are carefully blended without binders or other additives that could potentially adversely influence performance.
The blend of powders is isostatically compacted into a green billet under high pressure and vacuum sintered to near theoretical density. The billet is extruded and subjected to multiple rolling operations to produce sheet stock of the required thickness and a tight thickness tolerance.
An array of U.S. patents discloses the unique technologies that underlie the MetamicTM neutron absorber [3.3.2 -3.3.5].Holtec Report Hl- 2115004 3-3 Holtec Project 2119 In recognition of the central role of the neutron absorber in maintaining subcriticality, Holtec International utilizes appropriately rigorous technical and quality assurance criteria and acceptance protocols to ensure satisfactory neutron absorber performance over the service life of the fuel racks. Holtec International's Quality Assurance program ensures that MetamicTM will be manufactured under the control and surveillance of a Quality Assurance/Quality Control Program that conforms to the requirements of 1OCFR50 Appendix B, "Quality Assurance Criteria for Nuclear Power Plants." Consistent with its role in reactivity control, all neutron absorbing material manufactured for use in the Holtec racks is categorized as Safety Related (SR). SR manufactured items, as required by Holtec's NRC-approved Quality Assurance program, must be produced to essentially preclude, to the extent possible, the potential of an error in the procurement of constituent materials and the manufacturing processes.
Accordingly, material and manufacturing control processes must be established to eliminate the incidence of errors, and inspection steps are implemented to serve as an independent
'et of barriers to ensure that all critical characteristics defined for the material by Holtec's design team are met in the manufactured product.3.3.1 Characteristics of MetamicTM Because MetamicTM is a porosity-free material, there is no capillary path through which water can penetrate MetamicTM panels and chemically react with aluminum in the interior of the material to generate hydrogen.
Thus, the potential of swelling and generation of significant quantities of hydrogen is eliminated.
To determine its physical stability and performance characteristics, MetamicTM was subjected to an extensive array of tests sponsored by EPRI that evaluated the functional performance of the material at elevated temperatures (up to 900'F) and radiation levels (1E+ 11 rads gamma). The results of the tests documented in an EPRI report [3.3.6] indicate that MetamicTM maintains its physical and neutron absorption properties with little variation in its properties from the unirradiated state. The main conclusions provided in the above-referenced EPRI report, which Holtec Report Hl- 2115004 3-4 Holtec Project 2119 endorsed MetamicTM for dry and wet storage applications on a generic basis, are summarized below:* The metal matrix configuration produced by the powder metallurgy process with almost a complete absence of open porosity in MetamicTM ensures that its density is essentially equal to the theoretical density.* The physical and neutronic properties of MetamicTM are essentially unaltered under exposure to elevated temperatures (750'F -900'F).0 No detectable change in the neutron attenuation characteristics under accelerated corrosion test conditions has been observed.Additional technical information on MetamicTM in the literature includes independent measurements of boron carbide particle distribution in MetamicTM panels, which showed extremely small particle-to-particle distance [3.3.7]. The USNRC has previously approved MetamicTM for use in both wet storage [3.3.8] and dry storage [3.3.9] applications.
MetamicTM has also been subjected to independent performance assessment tests by Holtec International in the company's Florida laboratories since 2001 [3.3.1, 3.3.10]. The multi-year long experimental study simulated limiting environmental conditions in wet and dry storage. No anomalous material behavior was observed in any of the tests. These independent Holtec tests essentially confirmed earlier EPRI and other industry reports'cited in the foregoing with regard to the suitability of MetamicTM as a neutron absorber in fuel storage applications.
The design life of the MetamicTM in the fuel storage racks is 60 years. There are three aspects of material performance that are considered in determining design life: (1) resistance to corrosion, (2) resistance to gamma radiation, and (3) resistance to elevated temperatures.
These three aspects are discussed in the following paragraphs.
With respect to the resistance of MetamicTM to corrosion the water in a borated PWR spent fuel pool is, essentially, a dilute boric acid solution.
Section 7.2 of a Holtec proprietary test report[3.3.10] indicates that corrosion testing of coupons in a 2000 ppm boric acid solution has been performed.
As stated in the report, these tests "indicate that no corrosion was observed".
Section Holtec Report HI- 2115004 3-5 Holtec Project 2119 4.0 of another Holtec proprietary test report [3.3.1] indicates that corrosion testing of coupons in a 2500 ppm boric acid solution has been performed.
These tests "demonstrate the excellent corrosion resistance of properly-prepared Metamic." Both of these tests were performed for temperatures higher than would normally occur in the spent fuel pool (which would accelerate corrosion reactions).
As the SFP water does not corrode the MetamicTM, even under accelerated corrosion conditions, it can be concluded that corrosion will not reduce the design life of the MetamicTM.
With respect to the resistance of MetamicTM to gamma radiation, Section 5.0 of a Holtec proprietary test report [3.3.1] describes that sample coupons were exposed to gamma radiation up to 1.5x 1011 rads. The report states that "Metamic exhibits excellent dimensional stability after irradiation" and notes that "there was no change in Boron-10 areal density." It has been estimated
[3.3.11] that PWR fuel in storage in a spent fuel pool would expose adjacent neutron absorber to 2.4x10 1 0 rads in 40 years. Conservatively assuming that the dose accumulation rate in years 41 through 60 is equal to the average rate in years 2 through 40, the exposure over 60 years would be 3.24x1010 rads, still well below the test coupon exposure.
As the coupons were not adversely affected by a gamma dose that exceeds the dose from 60 years of exposure to fuel, it can be concluded that gamma radiation will not reduce the design life of the MetamicTM.
With respect to the resistance of MetamicTM to elevated temperatures, Section 3.2.2 of a Holtec proprietary test report [3.3.1 ] indicates that long-term temperature testing of has been performed.
The long-term tests were performed at 750'F for 8523 hours (nearly 1 year). Thermal aging tests are often performed using ýan Arrhenius-type rate equation, where the temperature versus time relationship is an inverse natural logarithm, so 1 year at 750'F is equivalent to approximately 87 years at 1687F (which bounds the long-term SFP local water temperatures).
These tests demonstrated no change in coupon length and width, a negligible change (0.00015")
in coupon thickness, no significant change in coupon weight, no change in B-10 concentration, and no change in density. As the elevated temperatures do not affect the MetamicTM, it can be concluded that elevated temperatures will not reduce the design life of the MetamicTM.
Holtec Report Hi- 2115004 3-6 Holtec Project 2119 Holtec Report Hl- 2115004 3-6 Holtec Project 2119 TABLE 3.3.1 PREVIOUS AND IN-PROCESS SPENT FUEL STORAGE EQUIPMENT WITH METAMIC T M Equipment Type Plant NRC Docket Spent Fuel Racks ANO Unit 2 50-368 Spent Fuel Racks Beaver Valley Unit 2 50-412 Spent Fuel Racks Clinton 50-461 Spent Fuel Racks Cooper 50-298 Spent Fuel Racks Diablo Canyon Unit 1 50-275 Spent Fuel Racks Diablo Canyon Unit 2 50-323 Spent Fuel Racks Pilgrim Unit 1 50-293 Spent Fuel Racks Shearon Harris Unit 1 50-400 Spent Fuel Racks TMI Unit 1 50-289 Neutron Absorber Inserts ANO Unit 1 50-313 Neutron Absorber Inserts St. Lucie Unit 1 50-335 Neutron Absorber Inserts St. Lucie Unit 2 50-389 Neutron Absorber Inserts Turkey Point Unit 3 50-250 Neutron Absorber Inserts Turkey Point Unit 4 50-251 Holtec Report HI- 2115004 3-7 Holtec Project 2119 Holtec Report Hl- 2115004 3-7 Holtec Project 2119 3A4 In-Service Surveillance of the Neutron Absorber 3A4.1 Purpose MetamicTM, the neutron absorbing material incorporated in the fuel storage rack design to assist in controlling system reactivity, consists of finely divided particles of boron carbide (B 4 C)uniformly distributed in Type 6061 aluminum powder. Tests simulating the radiation, thermal and chemical (water and boric acid) environment of the spent fuel pool have demonstrated the stability and chemical inertness of MetamicTM.
Based upon the accelerated test programs, MetamicTM is considered a satisfactory material for reactivity control in fuel storage racks and is fully expected to fulfill its design function over the lifetime of the racks. Nevertheless, as a defense-in-depth measure, a. MetamicTM surveillance program has been developed and will be implemented for the SFP in order to monitor the integrity and performance of MetamicTM.
The purpose of the surveillance program is to characterize certain properties of the MetamicTM with the objective of providing data necessary to assess the capability of the MetamicTM panels in the racks to continue to perform their intended function.
The surveillance program is also capable of detecting the onset of any significant degradation with ample time to take such corrective action as may be necessary.
The MetamicTM surveillance program depends primarily on representative coupon samples to monitor performance of the absorber material without disrupting the integrity of the storage system. The principal parameters to be measured are the thickness (to monitor for swelling) and B- 10 loading (to monitor for the continued presence of boron in the MetamicTM).
Holtec Report HI- 2115004 3-8 Holtec Project 2119 Holtec Report Hl- 2115004 3-8 Holtec Project 2119 3.4.2 Coupon Surveillance Program 3.4.2.1 Coupon Description
*The coupon measurement program includes coupons suspended on a mounting (called a tree), placed in a designated cell, and surrounded by spent fuel. Coupons are removed from the array on a prescribed schedule and certain physical quantities measured from which the stability and integrity of the MetamicTM in the storage cells may be inferred.The coupon surveillance program uses a tree with a total of 10 test coupons. In mounting the coupons on the tree, the coupons are positioned axially within the central eight feet (approximate) of the active fuel zone where the gamma flux is expected to be reasonably uniform.The coupons will be taken from the same lots of material as that used for construction of the racks. Each coupon will be carefully pre-characterized prior to insertion in the pool to provide reference initial values for comparison with measurements made after irradiation.
As a minimum, the surveillance coupons will be pre-characterized for weight, dimensions (especially thickness) and B-10 loading.3.4.2.2 Surveillance Coupon Testing Schedule To assure that the coupons will have experienced a slightly higher radiation dose than the MetamicTM in the racks, the coupon tree will be surrounded by freshly-discharged fuel assemblies after each of the first four offloads following installation.
At the time of the first fuel offload, the four storage cells surrounding the tree shall be loaded with freshly-discharged fuel assemblies from among those which are not scheduled to be returned to the core. At the scheduled test date, a coupon will be removed for evaluation.
Effort will be made to surround the coupon tree with freshly discharged fuel during each of the next three refueling discharges.
The fuel assemblies initially placed in the four cells surrounding the tree will be removed and Holtec Report HI- 2115004 3-9 Holtec Project 2119 replaced with freshly discharged assemblies and the tree will remain in place. The recommended coupon measurement schedule is shown in Table 3.4.1.Evaluation of the coupons removed will provide information of the effects of the radiation, thermal and chemical environment of the pool and by 'inference, comparable information on the MetamicTM panels in the racks. Over the duration of the coupon testing program, the coupons will have accumulated more radiation dose than the expected lifetime dose for normal storage cells. Coupons that have not been destructively analyzed' may optionally be returned to the storage pool and remounted on the tree. They will then be available for subsequent investigation of defects, should any be found.3.4.2.3 Measurement Program The coupon measurement program is intended to monitor changes in physical properties of the Metamic absorber material by performing the following measurements on the preplanned schedule:* Visual Observation and Photography" Neutron Attenuation" Dimensional Measurements (length, width and thickness)" Weight and Specific Gravity 3.4.2.4 Surveillance Coupon Acceptance Criteria Of the measurements to be performed on the MetamicTM surveillance coupons, the most important are (1) the neutron attenuation' measurements (to verify the continued presence of the boron) and (2) the thickness measurement (as a monitor of potential, swelling).
Acceptance criteria for these measurements are as follows: 1 Neutron attenuation measurements are a precise instrumental method of chemical analysis for Boron- 10 content using a nondestructive technique in which the percentage of ihermal neutrons transmitted through the panel is measured and compared with predetermined calibration data. Boron-10 is the nuclide of principal interest since it is the isotope responsible for neutron absorption in the Metamic panel.Holtec Report Hl- 2115004 3-10.Holtec Project 2119
" A decrease of no more than 5% in Boron-10 content, as determined by neutron attenuation, is acceptable.
This is equivalent to a requirement for no loss in boron within the accuracy of the measurement.
* An increase in thickness at any point should not exceed 10% of the initial thickness at that point.Changes in excess of either of these two criteria requires investigation and engineering evaluation, which may include early retrieval and measurement of one or more of the remaining coupons to provide corroborative evidence that the indicated changes are real. If the deviation is determined to be real, an engineering evaluation shall be performed to identify further testing or any corrective action that may be necessary.
The remaining measurement parameters serve a supporting role and should be examined for early indications of the potential onset of MetamicTM degradation that would suggest a need for further attention and possibly a change in measurement schedule.
These include (1) visual or photographic evidence of unusual surface pitting, corrosion or edge deterioration, or (2)unaccountable weight loss in excess of the measurement accuracy.Holtec Report HI- 2115004 3-il Holtec Project 2119 Holtec Report 111- 2115004 3-11 Holtec Project 2119 TABLE 3.4.1 RECOMMENDED COUPON MEASUREMENT SCHEDULE Coupon Years1 1 2 2 4 3 6 4 8 5 12.6 18 7 26 8 36 9 48 10 60 1 The years pertain to those after the installation of the SFP storage racks.Holtec Report HI- 2115004 3-12 Holtec Project 2119 Holtec Report Hl- 2115004 3-12 Holtec Project 2119
 
===3.5 References===
[3.3.1] "Use of METAMIC in Fuel Pool Applications," Holtec Information Report No. HI-2022871, Revision 1 (2002).[3.3.2] U.S. Patent # 6,332,906 entitled "Aluminum-SiliconAlloy formed by Powder", Thomas G. Haynes III and Dr. Kevin Anderson, issued December 25, 2001.[3.3.3] U.S. Patent # 5,965,829 entitled "Radiation Absorbing Refractory Composition and Method of Manufacture"', Dr. Kevin Anderson, Thomas G. Haynes III, and Edward Oschmann, issued October 12, 1999.[3.3.4] U.S. Patent # 6,042,779 entitled "Extrusion Fabrication Process for Discontinuous Carbide Particulate Metal and Super Hypereutectic Al/Si Alloys", Thomas G. Haynes III and Edward Oschmann, issued March 28, 2000.[3.3.5] U.S. Patent Application 09/433773 entitled "High Surface Area Metal Matrix Composite Radiation Absorbing Product", Thomas G. Haynes III and Goldie Oliver, filed May 1, 2002.[3.3.6] "Qualification of METAMIC for Spent Fuel Storage Application," EPRI, 1003137, Final Report, October 2001.[3.3.7] "METAMIC Neutron Shielding", by K. Anderson, T. Haynes, and R. Kazmier, EPRI Boraflex Conference, November 19-20 (1998).[3.3.8] "Safety Evaluation-by the Office of NuclearReactor Regulation Related to Holtec International Report HI-2022871 Regarding Use of Metamic in Fuel Pool Applications," Facility Operating License Nos. DPR-51 and NPF-6, Entergy Operations, Inc., Docket No. 50-313 and 50-368, USNRC, June 2003.[3.3.9] USNRC Docket No. 72-1004, NRC's Safety Evaluation Report on NUHOMS 61BT (2002).[3.3.10] "Sourcebook for MetamicTM Performance Assessment" by Dr. Stanley Turner, Holtec Report No. HI-2043215, Revision 3 (2010).[3.3.11] "Radiation Dose to Absorber Material in Wet Storage," Proprietary Holtec Position Paper WS- 119, Revision 3 (May 2010).Holtec Report HI- 2115004 3-13 Holtec Project 2119 CHAPTER 4: CRITICALITY CONSIDERATIONS
 
===4.1 Introduction===
This chapter documents the criticality safety evaluation for the storage of fresh and spent 15x 15 fuel' in new Region 1 racks with MetamicTM neutron absorbers at Palisades.
The objective of this chapter is to demonstrate that the effective neutron multiplication factor (keff) of the spent fuel pool (SFP) fully loaded with fuel of the highest anticipated reactivity, at a temperature corresponding to the highest reactivity is less than 1.0 for the pool flooded with un-borated water, and does not exceed 0.95 for the pool flooded with borated water, with a 95/95 confidence level. The maximum calculated reactivity includes a margin for uncertainty in reactivity calculations including manufacturing tolerances.
Reactivity effects of abnormal and accident conditions are also evaluated to assure that under all credible abnormal and accident conditions, the reactivity will not exceed the regulatory limit.Palisades currently has seven racks with Carborundum plate absorber which is no longer viable. These seven racks are being replaced by new MetamicTM racks of the Region 1 flux trap style (six in the main SFP and one in the north tilt pit). Note that Palisades currently also has six Region 2 style racks (with Boraflex panel absorber, but with no credit for Boraflex due to its degradation) that are not currently being replaced.
See Figure 4.1.1.The seven new Holtec International Region I MetamicTM racks are designed to accommodate fresh or spent 15x15 PWR fuel with an initial maximum nominal planar average enrichment of 5.0 wt% U-235. Since Region 1 cells are qualified for the storage of fresh fuel, any fuel assembly Palisades does not use a standard PWR 15x 15 design but has eight external solid zirc non-fuel guide bars (two per side) which hold the assembly together and also guide the control rods which are 'X' (cruciform) shaped and go between fuel bundles rather than control element assembles (CEAs), which most other PWRs have that go into the fuel bundle. The guide bars take the place of fuel rods in the outer rows of the fuel assembly.Holtec Report HI-2115004 4-1 Holtec Project 2119 (fresh or burned) meeting the maximum enrichment requirement may be stored in a Region 1 location.Criticality control in the Region 1 SFP storage racks relies on the following: " Fixed Neutron Absorbers.
o MetamicTM panels in the Region 1 racks." Soluble boron for normal and accident conditions in accordance with 1OCFR50.68(b)(4).
Criticality control in the Region 1 SFP storage racks does not rely on the following:
* Burnup of the fuel." Integral or non-integral absorbers (e.g., Gd).Holtec Report HI-2115004 4-2 Holtec Project 2119 N4 Main SFP Region 2 Rack Region 1 Rack Region 2 Rack North Tilt Pit FIGURE 4.1.1 -THE SFP AND NORTH TILT PIT LAYOUT OF PALISADES Holtec Report HI-2115004 4-3 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
 
===4.2 Methodology===
4.2.1 General Approach The analysis is performed in a manner such that the results are below the regulatory limit with a 95% probability at a 95% confidence level. The calculations are performed using either the worst case bounding approach or the statistical analysis approach with respect to the various calculation parameters.
The approach considered for each parameter is discussed below.4.2.2 Computer Codes MCNP5-1.51
[4.2.1] is used for the criticality analyses.
MCNP is a three-dimensional Monte Carlo code, selected because it has a long history of successful use in fuel storage criticality analyses and has all of the necessary features for the analysis to be performed for the Region 1 racks in the Palisades SFP. MCNP5-1.51 calculations use continuous energy cross-section data exclusively based on ENDF/B-VII.
The convergence of a Monte Carlo criticality problem is sensitive to the following parameters:
(1) number of histories per cycle, (2) the number of cycles skipped before averaging, (3) the total number of cycles and (4) the initial source distribution.
All MCNP5-1.51 calculations are performed with a minimum of 12,000 histories per cycle, a minimum of 200 skipped cycles before averaging, and a minimum of 200 cycles that are accumulated.
The initial source is specified as uniform over the fueled regions (assemblies).
Convergence is determined by confirming that the source distribution converged using the Shannon entropy and the keff was confirmed to converge by checking the output file warnings.4.2.2.1 MCNP5-1.51 Validation Benchmarking of MCNP5-1.51 for criticality calculations is documented in [4.2.2]. The benchmarking is based on the guidance in [4.2.3], and includes calculations for a total of 532 critical experiments with fresh U0 2 fuel, fresh MOX fuel, and fuel with simulated actinide composition of Holtec Report HI-2115004 4-4 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION spent fuel (HTC experiments
[4.2.2]).
The results of the benchmarking calculations show few significant trends, and indicate a truncated bias of 0.00002 with an uncertainty of +/- 0.0110 (95%probability, 95% confidence level) for the full set of all 532 experiments.
The statistical treatment used to determine those values considered the variance of the population about the mean and used appropriate confidence factors and trend analysis.
Note that the area of applicability for the MCNP5-1.51 benchmark is presented in Table 4.2.1 (a).4.2.2.2 MCNP5-1.51 Bias and Bias Uncertainty for Pure Water I 2 A positive bias which results in decrease in reactivity is truncated to zero [4.2.2].3 Since the number of experiments was more than 50, the k factor for 50 samples is conservatively used [4.2.2].Holtec Report HI-2115004 4-5 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.2.3 MCNP5-1.51 Bias and Bias Uncertainty for Borated Water Holtec Report HI-211.5004 4-6 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.3 Analysis Methods 4.2.3.1 Design Basis Fuel Assembly Approach Criticality calculations typically first determine which of the fuel designs being considered are the most reactive and then perform the analysis using that fuel bundle, called the design basis fuel assembly.
For this analysis, the design basis fuel has the maximum U-235 enrichment with no credit for gadolinium, with no blanket (the blanket regions are modeled as full enriched fuel), and the maximum fuel active region length.Palisades has used the 15x 15 PWR fuel (see Figure 4.5.1). The initial core was manufactured by CE, and subsequent reloads were manufactured by AREVA or its fuel manufacturing predecessor companies.
These fuel designs are all very similar and they are evaluated to determine which parameters are bounding so that a single design basis fuel assembly can be used for the analysis.To determine the design basis assembly, MCNP5-1.51 calculations are performed with a single cell MCNP5-1.51 Region 1 model (with reflective boundary conditions down the center of flux trap).4.2.3.2 Reactivity Effect of SFP Water Temperature 4.2.3.2.1 Region 1 SFP Racks The Palisades SFP has a normal pool water temperature operating range of 68 to 150 'F, where above 150 'F or below 68 'F is considered an accident condition.
For the nominal condition, the Criticality analysis should be performed at the most reactive temperature and density [4.2.4].Also, there may be temperature-dependent cross section effects in MCNP5-1.51 that need to be considered.
In general, both density and cross section effects may not have the same reactivity effect for all storage rack scenarios, since configurations with strong neutron absorbers typically show a higher reactivity at lower water temperature, while configurations without such neutron Holtec Report HI-2115004 4-7 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION absorbers typically show a higher reactivity at a higher water temperature.
For the new Region 1 storage racks which credit MetamicTM, the most reactive SFP water temperature and density is expected to be at 39.2 OF and 1 g/cc, respectively.
Further, the standard cross section temperature in MCNP5-1.51 is 293.6 K. Cross sections are also available at other temperatures; however, not usually at the desired temperature for the SFP criticality analysis.
MCNP5-1.51 has the ability to automatically adjust the cross sections to the specified temperature when using the TMP card. Furthermore, MCNP5-1.51 has the ability to make a molecular energy adjustment for select materials (such as water) by using the S(a,3)card 4.The S(a,p3) card is provided for certain fixed temperatures which are not always applicable to SFP criticality analysis.
Rather, there are limited temperature options, i.e., 293.6 K and 350 K, etc. MCNP5-1.51 does not have the ability to adjust the S(a,3) card for temperatures as it does for the TMP card discussed above. Additional studies are performed to show the impact of the S(t,3) card at the two available temperatures.
To determine the water temperature and density which result in the maximum reactivity, MCNP5-1.51 calculations are run using the bounding SFP temperature values. Additionally, S(a,3) calculations are performed for both upper and lower bounding S(a,p3) values, if needed.The studies mentioned above are performed for the following cases for the single cell MCNP5-1.51 Region 1 model (with reflective boundary conditions down the center of flux trap): Case la (reference case): Temperature of 39.2 'F (277.15 K) and a density of 1.0 g/cc are used to determine the reactivity at the low end of the temperature range (note that this is below the minimum normal temperature of 68 OF, and, therefore, represents the accident condition related to a cool down. It is conservatively used as the reference case). The S(a,3) card corresponds to a temperature of 68.81 'F (293.6 K).4 For more information about the S(a,p3) card see Reference
[4.2.1].Holtec Report HI-2115004 4-8 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION" Case lb: This case is like Case la, but has no S(a,13) card. This is used to show it is conservative to use the S(a,3) card.Case 2: Temperature of 150 'F (338.71 K) and a density of 0.98026 g/cc are used to determine the reactivity at the high end of the temperature range. The S(a,13) card corresponds to a temperature of 68.81 'F (293.6 K)." Case 3: Temperature of 150 'F and a density of 0.98026 g/cc. The S(a,c3) card corresponds to a temperature of 170.33 'F (350 K).The results of the temperature studies are then applied to all further calculations so that the most reactive water temperature and density is considered.
Note that the evaluations use the same MCNP5-1.51 models used in the design basis calculation.
4.2.3.2.2 Region 2 SFP Racks As discussed in Section 4.2.7, for the interface analysis (effect of Region 1 racks on the reactivity of Region 2 racks, and effect of Region 2 racks on the reactivity of Region 1 racks), MCNP5-1.51 models of the Region 2 racks and the interface of the Region 1 and Region 2 racks are developed.
To determine the water temperature and density which result in the maximum reactivity in Region 2 racks, MCNP5-1.51 calculations are run using the bounding SFP temperature values. Additionally, S(a,3) calculations are performed for both upper and lower bounding S(a,p3) values.The following studies are performed using an MCNP5-1.51 model of an 8.5x19 array of Region 2 cells: Case 1: Temperature of 39.2 'F (277.15 K) and a density of 1.0 g/cc are used to determine the reactivity at the low end of the temperature range (note that this is below the minimum normal temperature of 68 'F, and, therefore, represents the accident condition related to a cool down). The S(a,3) card corresponds to a temperature of Holtec Report HI-2115004 4-9 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 68.81 -F (293.6 K).* Case 2 (reference case): Temperature of 150 'F (338.71 K) and a density of 0.98026 g/cc are used to determine the reactivity at the high end of the temperature range. The S(,p3)card corresponds to a temperature of 68.81 'F (293.6 K).* Case 3: Temperature of 150 'F and a density of 0.98026 g/cc. The S(a,3) card corresponds to a temperature of 170.33 'F (350 K).The results of the temperature studies are then applied to all further calculations so that the most reactive water temperature and density is considered with respect to the Region 2 racks. Note that the MCNP5-1.51 models of Region 2 rack are discussed in Section 4.2.7.4.2.3.3 Fuel and Storage Rack Manufacturing Tolerances In order to determine the keff of the Region 1 racks at a 95/95 level, consideration is given to the reactivity effect of the PWR fuel and Region 1 storage rack manufacturing tolerances.
The reactivity effects of significant independent tolerance variations are combined statistically
[4.2.4]. The evaluations use the same MCNP5-1.51 models used in the design basis calculation.
4.2.3.3.1 Fuel Manufacturing Tolerances The Palisades fuel tolerances are presented in Table 4.5.1. The single cell Region 1 MCNP5-1.51 model is used to determine the reactivity effect of the tolerance, and the full value of the tolerance is applied for each case. Calculations are performed for both pure water and borated water. The MCNP5-1.51 tolerance calculation is compared to the MCNP5-1.51 result of the reference case at the 95/95 level using the following equation: delta-kala
= (kcalc2 -kcalci) +/- 2
* 4j (F1 2+ (722)Holtec Report HI-2115004 4-10 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION The following fuel tolerances are considered in this analysis: " Fuel pellet density" Fuel pellet outer diameter (OD)" Fuel rod pitch* Fuel cladding inner diameter (ID)* Fuel cladding OD" Instrumentation tube ID" Instrumentation tube OD" Guide bar width.The maximum positive reactivity effect of the MCNP5-1.51 calculations for each tolerance is statistically combined with the other tolerance results, and this result is then statistically combined with other uncertainties to determine keff.Further, the guide bar is almost like a trapezoid, but modeled as square such that its area is constant and the fuel to water ratio is maintained the same. The guide bar width tolerance is applied to all sides of each guide bar to maximize the impact of the tolerance.
4.2.3.3.2 Region 1 Storage Rack Manufacturing Tolerances The Region 1 storage rack manufacturing tolerances are presented in Table 4.5.3. The single cell Region 1 MCNP5-1.51 model is used to determine the reactivity effect of the tolerance, and the full value of the tolerance is applied for each case. Calculations are performed for both pure water and borated water. The MCNP5-1.51 tolerance calculation is compared to the MCNP5-1.51 result of the reference case at the 95/95 level using the following equation: delta-kcalc
= (kcalc2 -kcalcd) + 2
* 4(a1 2+ G2 2)Holtec Report HI-2115004 4-11 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION The following rack tolerances are considered in this analysis: " Storage cell inner diameter" Storage cell wall thickness" Storage cell pitch" Sheathing thickness* Poison pocket thickness.
The maximum reactivity effect of the MCNP5-1.51 calculations for each tolerance is then statistically combined with the other tolerance results, and this result is then statistically combined with other uncertainties to determine keff.Note that the poison thickness and loading were used at their minimum values; which mean they are treated as a bias (instead of uncertainties) for conservatism.
4.2.3.4 Fuel Radial Positioning The PWR fuel that is loaded in the Region 1 storage racks may not rest exactly in the center of the storage cell. Evaluations are performed to determine the most limiting radial location.
Four eccentric fuel positioning cases were analyzed:* Case 1: All fuel assemblies are positioned as far from the center of the 2x2 array as possible, as shown in Figure 4.2.1..Case 2: All fuel assemblies are positioned toward the center of the 2x2 array as possible, as shown in Figure 4.2.2.* Case 3: All fuel assemblies are positioned as far from the center of the 8x8 array as possible, as shown in Figure 4.2.3(a) and Figure 4.2.3(b).Holtec Report HI-2115004 4-12 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
* Case 4: All fuel assemblies are positioned toward the center of the 8x8 array as possible, as shown in Figure 4.2.3(c) and Figure 4.2.3(d).The maximum positive reactivity effect of the MCNP5-1.51 calculations for the fuel radial positioning is statistically combined with other uncertainties to determine keff.Note that the evaluations use the same MCNP5-1.51 models used in the design basis calculation, except the array sizes are larger. Further, the reference case for each eccentric positioning case is the design basis.4.2.3.5 Assemblies with Missing Fuel Rods In the Palisades SFP there are some assemblies with missing fuel rods. Older fuel assemblies with missing fuel rods are bounded by the design basis fuel assembly because their fuel enrichment is less than 4.2%. Analyses are performed to determine the reactivity effect of fuel assemblies with missing fuel rods. Any missing fuel rod replaced with a solid material is acceptable.
Representative cases, not all possible combinations, of a fuel assembly with missing four rods are evaluated for two scenarios:
Scenario 1: Missing Four Fuel Rods from One Assembly in a 3x3 Array For this scenario, it is assumed that the fuel assembly with missing fuel rods is in a Region 1 storage cell adjacent to eight Region 1 storage cells with complete fuel assemblies (i.e., with no missing fuel rods). The fuel assembly with missing fuel rods has four fuel rods replaced by water. 15 cases are evaluated.
Note that to address the positions of missing fuel rods in the assembly, fuel assembly columns are numbered from A to 0 (from left to right) and rows from 1 to 15 (from top to bottom). Figure 4.2.4 shows the MCNP5-1.51 models of several cases used for this study.The MCNP5-1.51 result of each case is compared to the MCNP5-1.51 result of the reference (Case 1) at the 95/95 level. The maximum 'kca]6 -kcalc,reference' is added as a bias, and the Holtec Report HI-2115004 4-13 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION maximum '2 */ (( caIc 2 + OTcalc,reference2), (95/95 uncertainty) is added as an uncertainty to determine keff. All calculations are performed for pure water and 850 ppm borated water.Scenario 2: Missing Four Fuel Rods from Every Assembly in SFP For this scenario, it is assumed that every fuel assembly in a Region 1 storage cell has four missing fuel rods. The missing fuel rods are replaced by water. 10 cases 'are evaluated.
Note that to address the positions of missing fuel rods in the assembly, fuel assembly columns are numbered from A to 0 (from left to right) and rows from 1 to 15 (from top to bottom). Figure 4.2.4 shows the MCNP5-1.51 models of several cases used for this analysis.The MCNP5-1.51 result of each case is compared to the MCNP5-1.51 result of the reference (Case 1) at the 95/95 level. The maximum 'kcalc -kcalc,reference' is considered as a bias, and the maximum '2
* I (0 calc 2 + Ccalc,reference2), (95/95 uncertainty) is considered as an uncertainty.
All calculations are performed for pure water and 850 ppm borated water.Note that these bias and bias uncertainty are provided as an option since very few assemblies have missing fuel rods. Thus, the bias and bias uncertainty values are not added explicitly for calculating, the maximum keff, instead they are added in the footnote of the tables which maximum keff values are provided.4.2.3.6 MetamicTM Coupon Measurement Uncertainty To account for the measurement uncertainty associated with the B- 10 content in the MetamicTM test coupons, an uncertainty of 5% 5 on the minimum areal density of the B 4 C amount in the MetamicTM is included in uncertainty analysis.5 Typical coupon measurements have an uncertainty less than 5%.Holtec Report HI-2 115004 4-14 Holtec Project 2119 Holtec Report HI-2115004 4-14 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION The evaluation uses the same MCNP5-1.51 models used in the design basis calculation.
The result is statistically combined with other uncertainties to determine keff. All calculations are performed for pure water and 850 ppm borated water.4.2.3.7 Reactivity Control Devices Palisades has used various burnable absorbers, such as Gd. The use of burnable absorbers does not increase the reactivity of a fresh fuel assembly, compared to an assembly lattice where all rods contain fuel and no burnable poison. In this analysis no credit is taken for any integral or non-integral absorbers.
4.2.3.8 Axial and Planar Enrichment Variations All calculations are conservatively performed using fresh fuel with an enrichment of 5.0 wt%, without any radial or axial variation (i.e., blankets are considered fully enriched).
That is conservative because the amount of fully enriched fuel in the model is greater than fuel with axial or planar enrichment variation.
4.2.4 Calculations to Determine keff Values 4.2.4.1.1 Maximum keff Calculation The calculation of the maximum keff of the Region 1 storage racks fully loaded with fresh PWR 15x15 fuel assemblies at the maximum enrichment of 5.0 wt% U-235 is determined by adding-all uncertainties and bias to the calculated reactivity.
Note that the MetamicTM dimensions and loading are taken at their worst case values. keff is determined by the following equation: keff = kcalc + uncertainty
+ bias Holtec Report HI-2115004 4-15.Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION where uncertainty includes:* Fuel manufacturing tolerances
* Region 1 storage rack manufacturing tolerances" Fuel rod positioning
* MetamicTM coupon measurement uncertainty
* MCNP5-1.51 bias calculation uncertainty (95%/95%)* MCNP5-1.51 calculation statistics (95%/95%, 2a)* Minimum water gap width between two Region 1 racks bias calculation uncertainty (95%/95%)" Missing four fuel rods bias calculation uncertainty (95%/95%)and the bias includes:* Calculation MCNP5-1.51 bias* Minimum water gap width between two Region 1 racks bias, if applicable" Fuel movement bias, if applicable" Missing four fuel rods bias, if applicable
* Region 2 interface effect bias, if applicable.
Note that each uncertainty is statistically combined with other uncertainties while biases are added together in order to determine keff.The approach used here takes credit for soluble boron under normal conditions (see Section 4.3).Under this approach, the limiting condition is the non-borated condition, which is shown to have a keff less than 1.0 at the 95/95 level.Holtec Report HI-2115004 4-16 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.4.1.2 Soluble Boron Concentration Calculations for normal and accident conditions for compliance with the regulatory limit of 0.95 at the 95/95 level and are performed at a fixed soluble boron level, selected such that the limit is met for all cases and conditions.
The design basis analysis with soluble boron is performed at 850 ppm, which is the minimum amount required for normal condition.
Note that the uncertainty analysis for the borated pool is performed at the Tech Spec minimum, except for the missing fuel rods analysis which is I performed which is performed with 850 ppm.Note that for accident conditions, 1350 ppm borated water is assumed, as stated in Table 4.5.2.4.2.5 Margin Evaluation The criticality analysis is performed using several conservative assumptions which introduce quantifiable margin into the analysis.
Two main conservative assumptions are:* Minimum B 4 C loading* Minimum MetamicTM thickness and width.To evaluate this margin, the same MCNP5-1.51 models used in the design basis calculation are used, but using the nominal poison thickness and loading.Further, a sensitivity analysis is performed to evaluate the effect of the MetamicTM B 4 C loading on reactivity, from 31% B 4 C loading (used in design basis calculation) to 25% B 4 C loading.4.2.6 Fuel Movement, Inspection and Reconstitution Operations Fuel movement, inspection and reconstitution are considered normal operation
[4.2.5]. The bounding case is the fuel elevator region which can hold 2 fuel assemblies (one in the elevator and Holtec Report HI-2115004 4-17 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION one in the inspection station).
To study the effect of the two fuel assemblies in the elevator region on the reactivity in the Region I storage racks, three cases are evaluated: " Case 1: This is the design basis fuel assembly.
This case is to show that the design basis fuel assembly case is bounding.* Case 2: This is the reference for Case 3. The MCNP5-1.51 model is same as Case 3, except with no fuel assembly in the elevator region." Case 3: The MCNP5-1.51 model is an 8x16 array of Region 1 storage cells, but a 2x6 array is cut off from the south part of the Region 1 rack to account for the fuel elevator region. At south, east and west, the 8x16 array is surrounded by water (the pool concrete wall is also replaced with water). A reflective boundary condition is used at north side of the Region 1 rack. The temperature of the model is set to the minimum (39.2 OF) with its corresponding water density and S(a,3) card. The temperature and density are bounding for the Region 1 racks. This model will evaluate the effect of two fuel assemblies in the elevator region on the reactivity of Region 1 racks. Figure 4.2.5 shows the MCNP5-1.51 model used for this analysis.Note that conservatively in these calculations, the offset between the centers of the elevator and the inspection station in north-south direction is ignored. That is conservative since fuel assemblies in the elevator region are modeled closer to each other compared to the actual situation.
Also, as shown in Table 4.5.2 (i.e., 'distance from edge of fuel assembly in the elevator to new MetamicTM rack wall (3 rd row)'), the fuel assemblies are modeled closer to the Region 1 racks than the actual distances.
The MCNP5-1.51 result of Case 3 is compared to the MCNP5-1.51 result of the reference case at the 95/95 level using the following equation to determine the effect of placing two fuel assemblies into the elevator region on reactivity:
delta-kcalc
= (kcalc2 -kcaicl) +/- 2
* j (0 1 2 + 12 2)Holtec Report HI-2115004 4-18 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
 
====4.2.7 Interfaces====
4.2.7.1 Region I to Region 1 Rack to Rack Water Gap Width Under certain circumstances, the Region 1 to Region 1 rack to rack gap width might be less than the flux trap width because the baseplate extensions between two racks are at the minimum, the poison pocket thickness and the sheathing thickness for both racks are at the maximum values, and the vertical tolerance which may cause the rack to "lean". To evaluate the effect of the minimum rack to rack water gap width on reactivity, the following case is used.Holtec Report 111-2115004 4-19 Holtec Project 2119 Holtec Report HI-2115004 4-19 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
* The MCNP5-1.51 model is an 8x8 array of Region 1 storage cells with the minimum rack to rack water gap width. Reflective boundary conditions are used down the center of water gap. Unlike the model of the design basis, the boundary sheathing is modeled as its maximum value to minimize the water gap. The temperature of the model is set to the minimum (39.2 OF) with its corresponding water density and S(a,3) card. The temperature and density are bounding for the Region 1 racks. This model will calculate the reactivity of a Region 1 rack when there rack to rack width gap is at the minimum. The MCNP5-1.51, model is shown in Figure 4.2.6.The MCNP5-1.51 result is compared to the MCNP5-1.51 result of the reference (design basis) at the 95/95 level. The 'kcalc -kcalc,reference' is added as a bias, and '2 * ] (C caIc2 + Ocalc,reference)
(95/95 uncertainty) is added as an uncertainty to determine keff.4.2.7.2 Region 1 to Region 2 Interface in the SFP Holtec Report 111-2115004 4-20 Holtec Project 2119 Holtec Report HI-2115004 4-20 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Holtec Report HI-2 115004 4-21 Holtec Project 2119 Holtec Report HI-2115004 4-21 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Holtec Report HI-2 115004 4-22 Holtec Project 2119 Holtec Report HI-2115004 4-22 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.7.2.1 Case 1: Effect of Region 1 on Reactivity of Region 2 Holtec Report 111-2115004 4-23 Holtec Project 2119 Holtec Report HI-2115004 4-23 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION"ft 4.2.7.2.2 Case 2: Effect of Region 2 on Reactivity of Region 1 Holtec Report HI-2115004 4-24 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Holtec Report HI-21 15004 4-25 Holtec Project 2119 A-j .......
SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.7.3 Region 1 to Region 2 Interface in the North Tilt Pit There are two Region 2 racks in the north tilt pit and between them will be a new Holtec Region 1 rack. Since the water gap width between the Region 1 rack and each of Region 2 racks is more than the water gap width between the new Region 1 racks and Region 2 racks in the SFP, the reactivity effect of Region 2 racks on Region 1 rack and vice versa are bounded with the interface calculations for the SFP.Holtec Report HI-2115004 4-26 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.8 Accident Condition The credible accidents considered are: the effect of temperature exceeding the normal range, dropped assemblies, storage cell distortion, misloaded (a fuel assembly in the wrong location within the storage rack), mislocated fuel assembly (a fuel assembly in the wrong location outside the storage rack), boron dilution and rack movement.
Those are briefly discussed in the following sections, and cases are identified that need to be analyzed specifically in Section 4.6 of this chapter.Note that the double contingency principle as stated in [4.2.4] specifies that "two unlikely independent and concurrent incidents or postulated accidents are beyond the scope of the required analysis." This principle precludes the necessity of considering the simultaneous occurrence of multiple accident conditions.
In this chapter, to evaluate the effect of accidents on the reactivity (except for the boron dilution and storage cell distortion accidents that are evaluated differently), 2-3 cases are evaluated for each accident (if an accident is not bounded by the other accidents), as follows.* Case 1: The reference case which is a normal condition without accident.
The water is pure." Case 2: The accident condition.
The water is pure." Case 3: The accident condition.
The water has 1350 ppm soluble boron.For Cases 1 and 2, the delta-k of the accident is calculated as: delta-k = (kcalcd -kcaUc2) + 2
* 1/(3 2 + Ca2 2)The accident conditions are considered at the 95/95 level using the total corrections from the design basis cases.Holtec Report HI-2115004 4-27 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.8.1 Temperature and Water Density Effects The SFP water temperature accident conditions for consideration are the decrease and increase in SFP water temperature below and above the nominal SFP temperature range of 68 to 150 OF. The decrease in temperature was already considered for the temperature coefficient determination as discussed in Section 4.2.3.2. A single failure of the cooling system would increase the pool temperature by only 3 OF. Therefore, an increase in temperature accident that leads to boiling in these racks is not considered credible.
However, to bound the potential increase in reactivity due to increased SFP temperature, the following cases are studied:* Case 1: This case the reference.
The water temperature is 39.2 OF (277.15 K) with the density of 1.0 g/cc. The S(a,c3) card corresponds to a temperature of 68.81 OF (293.6 K)." Case 2: At a temperature of 255 OF (397.04 K) and a density of 0.84591 g/cc. The S(a,13)card corresponds to a temperature of 260.33 °F (400 K). In this model, it is assumed that the water includes 10% void. Void is modeled as 10% decrease in density, compared to the density of water at 212 °F.4.2.8.2 Dropped Assembly -Horizontal For the case in which a fuel assembly is assumed to be dropped on top of a rack, the fuel assembly will come to rest horizontally on top of the rack with a separation distance from the active fuel region (as stated in Table 4.5.3). To evaluate the effect of the horizontally dropped fuel assembly on the reactivity three cases are evaluated: " Case 1: The MCNP5-1.51 model is the design basis. This case is the reference.
* Case 2: The MCNP5-1.51 model is an 8x19 array of Region 1 storage cells with a fuel assembly lain down on top the rack with a separation distance as stated in Table 4.5.3. The temperature of the model is set to the minimum (39.2 OF) with its corresponding water density and S(a,p3) card. The temperature and density are bounding for the Region 1 racks.Holtec Report HI-2115004 4-28 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Reflective boundary conditions are used at the center of flux trap. The water is pure. Figure 4.2.12 shows the MCNP5-1.51 model used for this analysis.* Case 3: This case is similar to Case 2, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.4.2.8.3 Dropped Assembly -Vertical into a Storage Cell It is also possible to vertically drop an assembly into a location that might be occupied by another assembly or that might be empty. Such a vertical impact would at most cause a small compression of the stored assembly, if present, or result in a small deformation of the baseplate for an empty cell.These deformations could potentially increase reactivity.
In a hypothetical non-mechanistic.
accident scenario, it is assumed that the dropped fuel assembly would damage the baseplate such that the dropped fuel assembly would touch the pool liner.Further, it is assumed that the baseplate in the cells adjacent to the cell where the dropped fuel assembly is dropped is also so damaged that the fresh fuel assemblies in those cells are dropped down by half the distance from the bottom of fuel assemblies to the pool liner 6. This is the bounding case since it is assumed that as a consequence of a dropped assembly vertically into a storage cell, parts of the dropped fuel assemblies which are below the sheathing are not covered by MetamicTM panels. To evaluate the effect of the vertically dropped fuel assembly on the reactivity three cases are evaluated:
6 Based on Chapter 7 of this licensing report, the maximum vertical deformation of baseplate in the impacted cell is 2.08" and the maximum vertical deformation of baseplate immediately adjacent to the impacted cell is 1.65". The calculated deformation values are much less than thevalues used in this analysis.Holtec Report 111-2115004 4-29 Holtec Project 2119 Holtec Report HI-2115004 4-29 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
* Case 1: The MCNP5-1.51 model is the design basis. This case is the reference." Case 2: The MCNP5-1.51 is an 8x8 array of Region 1 storage cells. A fresh fuel assembly at the center of the rack is dropped down such that 17 inches of the fuel assembly are not covered by MetamicTM panels. Also, the adjacent fuel assemblies are dropped down such that 8.5 inches of the fuel assembly are not covered by MetamicTM panels. The temperature of the model is set to the minimum (39.2 OF) with, its corresponding water density and S(a,3) card. These temperature and density are bounding for the Region 1 racks. Reflective boundary conditions are used at the center of flux trap. The water is pure. Figure 4.2.13 shows the MCNP5-1.51 model used for this analysis.* This case is similar to Case 2, but the water is borated to show that 1350 ppm- boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.4.2.8.4 Storage Cell Distortion 4.2.8.4.1 Storage Cell Distortion as a Result of a Dropped Fuel Assembly A storage celldistortion or altered geometry as a result of dropped fuel assembly is possible.
As evaluated in Chapter 7, the damage to the top of a MetamicTM panel would be less than 1.5 inch.Further, in the stated evaluation in Chapter 7, the MetamicTM panel and steel sheathing are not included as part of the structure.
The reactivity effect of this accident is bounded by the dropped fuel accident discussed in Section 4.2.8.3.4.2.8.4.2 Storage Cell Distortion as a Result of Fuel Handling Equipment Uplift Forces A storage cell distortion or altered geometry as a result of fuel handling equipment uplift forces is possible.
As evaluated in Chapter 7, there would not be any plastic deformation in racks due to these forces, and no separate calculation is performed for this storage cell distortion accident.Holtec Report HI-2 115004 4-30 Holtec Project 2119 Holtec Report HI-2115004 4-30 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.8.5 Misloaded Fresh Fuel Assembly Since the fuel storage racks are qualified for storage of fresh fuel of the highest anticipated reactivity, the misloading of a fresh fuel assembly is of no concern.4.2.8.6 Mislocated Fresh Fuel Assembly The Palisades SFP layout was looked at to determine possible worst case locations for a mislocated fresh 1 5xl 5 fuel assembly.
The worst case locations for a mislocated fuel assembly are the locations where the neutron leakage is minimal while the mislocated fuel assembly can be adjacent to as many as fuel assemblies as possible.
Two hypothetical locations where a fuel assembly may be mislocated are the elevator region, and a location in the north tilt pit between the Regions 1 and 2 racks. The two cited cases are evaluated, as follows: 4.2.8.6.1 Case 1: Mislocation of a Fuel Assembly in Elevator Region The elevator region has a capacity for two fuel assemblies.
The worst locations in the elevator region for a mislocated fresh 15x 15 fuel assembly are:* In the comer of the elevator region, in the area between the Region 1 rack and the fuel assembly in the elevator.* Adjacent to the fuel assembly in the inspection station.To evaluate the effect of the mislocation of a fuel assembly in the elevator region, five cases are evaluated:
Case la: This case is a reference case for Cases lb and Ic. The MCNP5-1.51 model is similar to the MCNP5-1.51 models of Cases lb and 1c, but without the mislocated fuel assembly, and all fuel assemblies are centered in storage cells.Holtec Report HI-2115004 4-31 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION" Case lb: This case is to model the mislocated fuel assembly at the comer of the elevator region. The MCNP5-1.51 model is a 7.5x17 array of Region 1 storage cells, with 6x2 cells within one side allocated for the elevator region. The elevator region does not include any structural components but only the fuel assembly.
At south, east and west, the rack is surrounded with water (the pool concrete wall is also replaced with water). Two fresh fuel assemblies are placed at the elevator and inspection station (as stated in Section 4.2.6, the Offset between the centers of the elevator and the inspection station in the north-south direction is ignored. Also, these fuel assemblies are modeled closer to the Region 1 racks than the actual distances).
The third fresh fuel assembly (the mislocated fuel assembly) is modeled at the area between Region 1 rack and the fuel assembly in the elevator.
Fuel assemblies in the rack are eccentric toward the mislocated fuel assembly.
The MCNP5-1.51 model is shown in Figure 4.2.14.* Case lc: This case is to model the mislocated fuel assembly at the south of the inspection station. The MCNP5-1.51 model is a 7.5x17 array of Region 1 storage cells, with 6x2 cells within one side allocated for the elevator region. The elevator region does not include any structural components but only the fuel assembly.
At south, east and west, the rack is surrounded with water (the pool concrete wall is also replaced with water). Two fresh fuel assemblies are placed at the elevator and inspection station (as stated in Section 4.2.6, the offset between the centers of the elevator and the inspection station in the north-south direction is ignored. Also, these fuel assemblies are modeled closer to the Region 1 racks than the actual distances).
The third fresh fuel assembly (the mislocated fuel assembly) is modeled adjacent, on the south side, to the fuel assembly in the inspection station. Fuel assemblies in the rack are eccentric toward the mislocated fuel assembly.
The MCNP5-1.51 model is shown in Figure 4.2.15.* Case Id: This case is similar to Case lb, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limitat a 95/95 level.* Case le: This case is similar to Case 1c, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.Holtec Report HI-2115004 4-32 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.2.8.6.2 Case 2: Mislocation of a Fuel Assembly in North Tilt Pit A possible location to mislocate a fuel assembly would be in the water gap between Region 1 and Region 2 racks in the north tilt pit. As the worst cases, the fuel rods in the mislocated fuel assembly would be lined up with either fuel rods in Region 1 rack, or fuel rods in Region 2 rack and the gap between these racks is reduced to just allow the mislocated fuel assembly to fit between them. To evaluate the effect of the mislocation of a fuel assembly in the north tilt pit on the reactivity five cases are evaluated: " Case 2a: This case is a reference case for Case 2b and 2c. The only difference is that the MCNP5-1.51 model does not include the mislocated fuel assembly." Case 2b: The MCNP5-1.51 model is an 8x16 array of Region 1 storage cells, a 9x18 array of Region 2 racks, and with a water gap between them equal to the minimum distance which a fuel assembly can be mislocated (i.e., the gap is reduced to match the fuel assembly width). The Region 1 and Region 2 racks are surrounded with more than 12 inches of water.The water gap includes a fresh mislocated fuel assembly' in the center. The array sizes are required in order to approximately match the sizes of the Region 1 rack and Region 2 rack, which have different cell pitches and cell inner diameters.
The mislocated fuel assembly is lined up exactly with the fuel in the Region 1 rack cells. Fuel rods in the Regions 1 and 2 racks are eccentric toward the mislocated fuel assembly.
Figure 4.2.16(a) and Figure 4.2.16(b) shows the MCNP5-1.51 model used for this analysis.Case 2c: The MCNP5-1.51 model is an 8x16 array of Region 1 storage cells, a 9x18 array'of Region 2 racks, and with a water gap between them equal to the minimum distance which a fuel assembly can be mislocated.
The Region 1 and Region 2 racks are surrounded with more than 12 inches of water. The water gap includes a fresh mislocated fuel assembly in the center. The array sizes are required in order to approximately match the sizes of the Region 1 rack and Region 2 rack, which have different cell pitches and cell inner diameters.
The mislocated fuel assembly is lined up exactly with the fuel in the Region 2 rack cells.Holtec Report HI-2115004 4-33 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Fuel rods in the Regions 1 and 2 racks are eccentric toward the mislocated fuel assembly.Figure 4.2.16(a) and Figure 4.2.16(c) shows the MCNP5-1.51 model used for this analysis." Case 2d: This case is similar to Case 2b, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.* Case 2e: This case is similar to Case 2c, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.4.2.8.7 Boron Dilution The Technical Specifications require the normal fuel pool boron concentration to be at least 1720 ppm, an 870 ppm margin to the 0.95 limit is present for the deboration event. Reference
[4.2.6]states that "The evaluation shows that a large volume of water (123,007 gallons) is necessary to dilute the SFP from the present TS limit of 1720 ppm to a soluble boron concentration where a keff of 0.95 would be approached in the pool. For the limiting dilution source flow rate, the dilution time to reach a pool concentration of 850 ppm was determined to be 9.8 hours." The above discussion shows that the 850 ppm takes the boron dilution into account; therefore, no more analysis is performed.
4.2.8.8 Rack Movement In the event of seismic activity, there is a hypothetical possibility that the storage rack arrays may move and come closer to each other. In the worst case scenario, two racks may touch each other with no flux trap between. To evaluate the effect of the rack movement on the reactivity three cases are evaluated:
* Case 1: This case is the reference case for Case 2. The MCNP5-1.51 model is similar to that of Case 2, but with box-to-box water gap width between Region I racks as cited in Table 4.5.3.Holtec Report HI-2115004 4-34 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION
* Case 2: The MCNP5-1.51 model is an 8x8 array of Region 1 storage cells with no water gap at the boundary.
Reflective boundary conditions are used along the outside of external sheathing.
Unlike the model of the design basis, the boundary sheathing is modeled as its maximum value. The temperature of the model is set to the minimum (39.2 OF) with its corresponding water density and S(a,p3) card. The temperature and density are bounding for the Region 1 racks. The water is pure. This model will calculate the reactivity of a Region 1 rack when there is no flux trap at the boundary.
Figure 4.2.17 shows the MCNP5-1.51 model used for this analysis." Case 3: This case is similar to Case 2, but the water is borated to show that 1350 ppm boron is sufficient to provide enough offset to meet the regulatory limit at a 95/95 level.Note that the evaluated scenario is bounding and conservatively non-mechanistic since rack baseplates preclude racks from touching each other.Holtec Report HI-2115004 4-35 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.2.1 (a)
 
==SUMMARY==
OF THE AREA OF APPLICABILITY OF THE MCNP5.1.51 BENCHMARK Holtec Report HI-21 15004 4-36 Holtec Project 2119 Holtec Report HI-2115004 4-36 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.2.1 (b)ANALYSIS OF THE UNBORATED AND BORATED WATER FOR THE MCNP5-1.51 CALCULATIONS
[4.2.2]Holtec Report HI-2 115004 4-37 Holtec Project 2119 Holtec Report HI-2115004 4-37 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.2.1 (c)BIAS AND BIAS UNCERTAINTY AS A FUNCTION OF INDEPENDENT PARAMETER FOR SFP RACKS FILLED WITH UN-BORATED (FRESH) WATER [4.2.2][ I_____________________________________________________________________________
Holtec Report HI-2 115004 4-38 Holtec Project 2119 Holtec Report HI-2115004 4-38 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.2.1 (d)THE BIAS AND BIAS UNCERTAINTY FOR SFP RACKS FILLED WITH PURE WATER Holtec Report HI-2115004 4-39 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.2.1 (e)THE BIAS AND BIAS UNCERTAINTY FOR SFP FILLED WITH BORATED WATER Description Bias Bias Uncertainty From Table 4.2.1 (b) -0.0004 0.0054-0.0023 0.0078 Note 1: The bolded values were used for the maximum keff calculations.
Holtec Report HI-2115004 Holtec Report HI-2 115004 4-40 Holtec Project 2119 4-40 Holtec Project 2119 FIGURE 4.2.1 -A 2-D REPRESENTATION OF THE MCNP5-1.51 REGION 1 RACKS ECCENTRIC FUEL POSITIONING MODEL (2x2 cells toward outside model)Holtec Report HI-2115004 4-41 Holtec Project 2119 FIGURE 4.2.2 -A 2-D REPRESENTATION OF THE MCNP5-1.51 REGION I RACKS ECCENTRIC FUEL POSITIONING MODEL (2x2 cells toward center model)Holtec Report HI-2115004 4-42 Holtec Project 2119 (a) (b)(c) (d)FIGURE 4.2.3 -A 2-D REPRESENTATION OF THE MCNP5-1.51 REGION 1 RACKS ECCENTRIC FUEL POSITIONING MODEL (a) Wide view of all assemblies toward outside; (b) 2x2 view of all assemblies toward outside;(c) wide view of all assemblies toward center; (d) 2x2 view of all assemblies toward center.Holtec Report HI-2115004 4-43 Holtec Project 2119 (a)(b)(c, (d)(e)(f)FIGURE 4.2.4 -A 2-D REPRESENTATION OF THE MCNP5-1.51 REGION I RACKS WITH MISSING FOUR FUEL RODS For Figure 4.2.4(a) through Figure 4.2.4(d), the assembly with the missing fuel rods is in the center cell.(a) Missing rods in A-i, A-15, 0-1 and 0-15; (b) Missing rods in C-3, C-13, M-3 and M-13;(c) Missing fuel rods in E-5, F-6, J-10 and K-11; (d) Missing rods in F-6, G-7, 1-9 and J-10;(e) Missing fuel rods in E-5, E- 11, K-5 and K-11; (f) Missing fuel rods in E-8, H-5, H-Il and K-8.Holtec Report HI-2115004 4-44 Holtec Project 2119 N Elevator Region Fuel Assembly in Inspection Station Fuel Assembly in Elevator FIGURE 4.2.5 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF TWO FUEL ASSEMBLIES IN THE ELEVATOR REGION Holtec Report HI-2 115004 4-45 iloltec Project 2119 Holtec Report HI-2115004 4-45 Holtec Project 2119 FIGURE 4.2.6 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF REGION 1 RACK WITH THE MINIMUM RACK TO RACK WIDTH DISTANCE.Holtec Report HI-2115004 4-46 Holtec Project 2119 THIS FIGURE CONTAINS HOLTEC PROPRIETARY INFORMATION FIGURE 4.2.7 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL Holtec Report HI-2 115004 4-47 Holtec Project 2119 Holtec Report HI-2115004 4-47 Holtec Project 2119 Water FIGURE 4.2.8 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF REGION 1, 7.5X17 ARRAY Only part of the model is shown for a better resolution.
Holtec Report HI-2 115004 4-48 Holtec Project 2119 Holtec Report HI-2115004 4-48 Holtec Project 2119 FIGURE 4.2.9 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF REGION 2, 8.5X19 ARRAY Only part of the model is shown for a better resolution.
Holtec Report HI-2115004 4-49 Holtec Project 2119 T Water FIGURE 4.2.10 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF INTERFACE FOR CALCULATING THE EFFECT OF REGION 1 RACK ON REGION 2 RACK REACTIVITY The fuel assemblies are not shown for a better resolution.
iloltec Report HI-2 115004 4-50 Holtec Project 2119 Holtec Report HI-2115004 4-50 Holtec Project 2119 THIS FIGURE CONTAINS HOLTEC PROPRIETARY INFORMATION FIGURE 4.2.11 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF INTERFACE 7 Holtec Report HI-21 15004 4-51 Holtec Project 2119 Holtec Report HI-2115004 4-51 Holtec Project 2119 Dropped Fuel Assembly (a)Dropped Fuel Assembly (b)FIGURE 4.2.12 D REPRESENTATIONS OF THE MCNP5-1.51 MODEL OF HORIZONTALLY DROPPED FUEL ASSEMBLY ON TOP OF THE REGION 1 RACKS (a) y-z direction; (b) x-z direction.
Holtec Report HI-2 115004 4-52 Holtec Project 2119 Holtec: Report HI-2115004 4-52 Holtec Project 2119 Dropped Fuel; Assemblies FIGURE 4.2.13 D REPRESENTATIONS OF THE MCNP5-1.51 MODEL OF VERTICALLY DROPPED FUEL ASSEMBLY Holtec Report HI-2115004 4-53 Holtec Project 2119 Elevator Region Fuel Assemblies in Elevator and Inspection Station Misloctaed Fuel Assembly (a)(b)FIGURE 4.2.14 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF MISLOCATED FUEL ASSEMBLY IN A CORNER OF THE ELEVATOR REGION (a) Sketch of the whole model; (b) position of mislocated fuel assembly.Holtec Report HI-21 15004 4-54 Holtec Project 2119 Holtec Report HI-2115004 4-54 Holtec Project 2119 Elevator Region Misloctaed Fuel Assembly Fuel Assemblies in Elevator and Inspection Station (a)Fuel Assembly in Inspection Station Mislocated Fuel Assembly (b)FIGURE 4.2.15 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF MISLOCATED FUEL ASSEMBLY IN THE ELEVATOR REGION, AT THE SOUTH OF THE INSPECTION STATION (a) Sketch of the whole model; (b) position of mislocated fuel assembly.Holtec Report HI-2115004 4-55 Holtec Project 2119 Mislocated Fuel Assembly (a)(b)(c)FIGURE 4.2.16 D REPRESENTATIONS OF THE MCNP5-1.51 MODEL OF MISLOCATED FUEL ASSEMBLY IN THE NORTH TILT PIT (a) Wide view of the model; (b) location of the mislocated fuel assembly, lined up with fuel rods in Region 1 rack; (c) location of the mislocated fuel assembly, lined up with fuel rods in Region 2 rack.Holtec Report HI-2 115004 4-56 Holtec Project 2119 Holtec Report HI-2115004 4-56 Holtec Project 2119 FIGURE 4.2.17 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF PART OF REGION 1 RACK MOVEMENT Only part of the model is shown for a better resolution.
Holtec Report HI-2115004 4-57 Holtec Project 2119 4.3 Acceptance Criteria 4.3.1 Applicable Codes, Standards and Guidance's Codes, standard, and regulations or pertinent sections thereof that are applicable to these analyses include the following:
* Code of Federal Regulations, Title 10, Part 50, Appendix A, General Design Criterion 62,"Prevention of Criticality in Fuel Storage and Handling."* Code of Federal Regulations, Title 10, Part 50.68, "Criticality Accident Requirements." 0 USNRC Standard Review Plan, NUREG-0800, Section 9.1.1, Criticality Safety of Fresh and Spent Fuel Storage and Handling, Rev. 3 -March 2007." L. Kopp, "Guidance on the Regulatory Requirements for Criticality Analysis of Fuel Storage at Light-Water Reactor Power Plants," NRC Memorandum from L. Kopp to T.Collins, August 19, 1998.* ANSI ANS-8.17-1984, Criticality Safety Criteria for the Handling, Storage and Transportation of LWR Fuel Outside Reactors." USNRC, NUREG/CR-6698, Guide for Validation of Nuclear Criticality Safety Calculational Methodology, January 2001.* DSS-ISG-2010-01, Revision 0, Staff Guidance Regarding the Nuclear Criticality Safety Analysis for Spent Fuel Pools.Holtec Report HI-2115004 4-58 Holtec Project 2119
 
===4.4 Assumptions===
The analyses apply a number of assumptions, either for conservatism or to simplify the calculation approach.
Each assumption is appropriately discussed and justified in the text.Important aspects of applying those assumptions are as follows: 1. Bounding or sufficiently conservative inputs and assumptions are used essentially throughout the entire analyses, and as necessary studies are presented to -show that the selected inputs and parameters are in fact conservative or bounding.2. Neutron absorption in minor structural members of the fuel assembly is neglected, e.g., spacer grids are replaced by water. Any increase in reactivity, if any, due to replacing spacer grids-with water would be offset with margins included in the model.3. The neutron absorber length in the rack is more than the active region of the fuel, but it is modeled to be the same length.4. A fuel pellet stack density is assumed to be equal to the pellet density, and is conservatively modeled as a solid right cylinder over the entire active length, neglecting dishing and chamfering.
This is acceptable since the amount of fuel modeled is more than the actual amount.5. The presence of burnable absorbers in fresh fuel is neglected, as discussed in Section 4.2.3.7..6. For the MetamicTM, only the worst case bounding material specifications are used (minimum B 4 C loading, minimum width and minimum thickness).
: 7. All models are laterally infinite arrays of the respective configuration, neglecting lateral leakage. The exception is where the model boundaries are water. Those include mislocation of a fuel assembly, interface models and fuel elevator models.8. All fuel cladding materials are modeled as pure zirconium, while the actual fuel cladding consists of one of several zirconium alloys. This is acceptable since the model neglects the trace elements in the alloy which provide additional neutron absorption.
: 9. Guide bars are modeled as square such that the amount of zirconium is maintained constant.Holtec Report HI-2115004 4-59 Holtec Project 2119
: 10. It is conservatively assumed that the water reflector below and above the racks is pure water with at least 12 inches, essentially an infinite reflector.
Holtec Report HI-2115004 4-60 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.5 Input Data 4.5.1 Fuel Assembly Specification The SFP racks are designed to accommodate 15x15 PWR fuel assembly with the specifications presented in Table 4.5.1. Based on dimensions of fuel rods, two main fuel designs have been used, which are fuel assemblies before "Batch R" and fuel assemblies from Batch R and beyond.The differences between these two types include:* The active fuel length" The cladding ID" The pellet diameter Note that the delivery date of fuel assemblies before Batch R was before 1998, and for Batch R and beyond has been since 1998. All fuel assemblies before Batch R were discharged before 2004.Also note that some of fuel assemblies used in the Palisades before Batch R had slightly different active fuel length, cladding OD, cladding ID, and pellet diameter.
However, since all those fuel assemblies had lower U-235 enrichment (less than 4.2%) than the two fuel assemblies analyzed in this chapter, the fuel assemblies evaluated in this chapter are bounding.4.5.2 SFP Parameters The SFP parameters are provided in Table 4.5.2.Holtec Report HI-2 115004 4-61 Holtec Project 2119 Holtec Report HI-2115004 4-61 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.5.3 Storage Rack Specification 4.5.3.1 Region 1 The Region 1 storage rack specifications that are used in the criticality analysis are summarized in Table 4.5.3, and the pool parameters are summarized in Table 4.5.2.The Region 1 rack cells are composed of stainless steel boxes separated by a water gap, with fixed neutron absorber (MetamicTM) panels centered on each side. The steel walls define the storage cells, and stainless steel. sheathing supports the neutron absorber panel and defines the boundary of the flux-trap (water gap) used to augment reactivity control. Stainless steel channels (water gap flats) connect the storage cells in a rigid structure and define the flux-trap between the neutron absorber panels. MetamicTM panels are installed on all exterior walls facing other racks.The MCNP5-1.51 rack model consists of a single rack cell (rack cell wall, neutron absorber, sheathing and water gap) with reflective boundary conditions through the centerline of the water gaps, thus simulating an infinite array of Region 1 storage racks. The storage rack cell is modeled the same length as the active fuel and all other storage rack materials are neglected.
The neutron absorber is modeled with the worst case bounding values, and the MetamicTM panel is centered in the gap between the cell wall and sheathing as shown in Figure 4.5.3. The rack has two sheathing types, boundary sheathing and inner sheathing.
The boundary sheathing is along the exterior of the rack model only and is thicker than the inner sheathing (the boundary sheathing is thicker than the inner sheathing to provide protection to the rack during transport).
The rack model uses the inner sheathing as described in Section 4.2.The SFP storage racks model is shown in Figure 4.5.1 and Figure 4.5.2.4.5.3.2 Material Compositions The MCNP5-1.51 material card specification is provided in Table 4.5.4 and Table 4.5.5.Holtec Report HI-21 15004 4-62 Holtec Project 2119 Holtec Report HIý2115004 4-62 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 4.5.3.3 Region 1 to Region 2 Interface Region 2 spent fuel racks are designed to accommodate a fuel assembly with the maximum fresh fuel enrichment equivalent of an amount given in Table 4.5.1. The Region 2 rack specifications, used for interface calculations, are provided in Table 4.5.3. The Region 2 rack model is shown in Figure 4.5.4.Holtec Report 111-2115004 4-63 Holtec Project 2119 Holtec Report HI-2115004 4-63 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.1 FUEL ASSEMBLY SPECIFICATIONS Fuel Assemblies Fuel Assemblies Before Batch R Batch R and Parameter Beyond Tolerance Value Value Assembly type 15xl5 15x15 N/A Fuel Assembly width, in. 8.195 8.195 N/A Rod pitch, in. 0.550 0.550 +0.01/14 *t Active length, in. ttt 131.80 132.6 N/A Maximum pellet theoretical 10.5312 10.5312 density, g/cc (+/-1.50%)(% of theoretical density) (96%) (96%)Total number of fuel rods 216 216 N/A Cladding OD, in. 0.417 0.417 +/-0.002 Cladding ID, in. 0.358 0.367 +/-0.0015 Cladding material Zr Zr N/A Pellet diameter, in. 0.35 0.3600 +/-0.0005 Maximum U-235 enrichment, 5 5 N/A wt%Region 2 fresh fuel enrichment 1.14 (max) 1.14 (max) N/A equivalent, wt%Guide bars Number of guide bars 8 8 N/A Guide bar width, in. I 0.398 0.398 +0.005 Guide bar area, in.2  0.1586 0.1586 N/A Guide bar material Zr Zr N/A Number of instrumentation 1 1 N/A Tubes Instrumentation tube OD, in. 0.417 0.417 +/-0.002 Instrumentation tube ID, in. 0.3670 0.3670 +/-0.0015 Instrumentation tube material Zr Zr N/A Holtec Report HI-2115004 4-64 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Fuel assembly batches before Batch R were delivered before 1998, and discharged before 2004.Also note that some fuel assemblies used in the Palisades before Batch R had slightly different active fuel length, cladding OD, cladding ID, and pellet diameter.
However, since all those fuel assemblies had less U-235 enrichment than the two fuel assemblies described in this'table, the two fuel assemblies evaluated in this chapter are bounding." This value is the average increase in pitch due to change in assembly width. It is assumed that this change is applied to all rod to rod clearances.
Note that the minimum pitch tolerance is not considered in the calculations."t The active fuel region for fuel stored in the spent fuel pool is within the axial range of 2.8" to 136.0" above the fuel assembly seating surface.Some fuel assemblies have fewer fuel rods, but the total number of fuel rods cited in the table is typical and bounding.* Both Zircaloy and M5 are used as cladding and instrumentation tube materials.
Both materials are Zr base.A guide bar is almost like a trapezoid, but modeled as square such that its area is constant.The guide bar width tolerance is applied to all sides of the square together, which is a conservative approach.For tolerance study of instrumentation tube, the thickness is not kept constant.Note 1: The design basis fuel assembly is based on data provided under column of "Fuel Assemblies Batch R and Beyond." As shown in Table 4.6.1, the fuel assemblies of Batch R and beyond are bounding.Holtec Report HI-2115004 4-65 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.2(a)MAIN SFP AND NORTH TILT PIT PARAMETERS Parameter Value Value Used 850 (minimum amount required Tech Spec minimum boron for normal condition), used for concentration for normal 1720 design basis analysis condition, ppm 1720, used for uncertainty analysis Tech Spec minimum boron concentration for accident 1350 1350, used for accident analysis condition, ppm Normal conditions Pool temperature, OF 68 -150 39.2 (most reactive temperature)
Pool water density, g/cc 0.99821 at 68 OF 1.0 0.98026 at 150 OF (water density corresponding to the most reactive temperature)
Accident conditions Upset temperature, OF 212 255 Upset water density, g/cc 0.95837 0.84591 Holtec Report HI-2 115004 4-66 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.2(b)MAIN SFP AND NORTH TILT PIT PARAMETERS Parameter Value Value Used Elevator region Distance from west pool wall to center of 59.875 59.875 fuel elevator, in.Distance from center of fuel elevator to 16.875 16.875 center of inspection station, in.Distance from south pool wall to new 3.11 3.11 MetamicTM rack wall (1 st row), in.Distance from south pool wall to new MetamicTM rack wall (3 rd row), in. 23.61 23.61 Distance from fuel elevator center to new MetamicTM rack wall (3 row), in. 8.61 5.5 Distance from edge of fuel assembly in the elevator to new MetamicTM rack wall 4.551 2.035 (3rd row), in.Fuel elevator center to inspection station 1.75 0.00 center N-S offset, in.Distance from south pool wall to elevator 15 15 center, in.Distance from west pool wall to new 3.27 3.27 MetamicTM rack wall, in.Distance from west pool wall to new MetamicTM rack wall, in. 5.63 5.63 Holtec Report HI-2 115004 4-67 Holtec Project 2119 Holtec Report HI-2115004 4-67 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.3(a)FUEL RACK PARAMETERS AND DIMENSIONS, REGION 1 Parameter Value Tolerance Cell ID, in.Wall thickness, in. .Cell pitch, in.Poison thickness, in.Poison width, in.Poison pocket thickness, in.B4 C loading in MetamicTM, % ' B- 10 areal density, g B- I10/cm 2, t Internal sheathing thickness, in.External sheathing thickness, in.Sheathing inside width, in. Distance from pool liner to baseplate, in. ": Baseplate thickness, in.Distance from baseplate to poison bottom, in.Poison length, in.Distance from poison top to top of rack, in. : Sheathing-to-sheathing flux trap width, in. : ;Minimum baseplate extension, in. tt it: Sewe o a ,i iMinimum sheathing-to-sheathing water gap width Box-to-box water gap width between Region 1 and Region 2 racks, in.Minimum water gap width between Region 1 and Region 2 racks in north tilt pit, in. f Holtec Report HI-2 115004 4-68 Holtec Project 2119 Holtec Report Hl-,2115004 4-68 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION The nominal B-10 areal density loading corresponds to the nominal B 4 C loading in MetamicTM, and the nominal poison thickness.
The minimum B-10 areal density loading corresponds to the minimum B 4 C loading in MetamicTM, and the minimum poison thickness.
* The cited thickness is the minimum thickness which a fuel assembly may accidently be mislocated between Region 1 and Region 2 racks.$ Vertical tolerance of cell walls: each rack cell shall be vertical to within [ of a vertical line between the top and bottom of the cell The minimum sheathing-to-sheathing water gap width between Region 1 racks is calculated using the minimum baseplate extension and the vertical tolerance of cell walls.Note that the vertical tolerance of cell walls is maximum at top of the rack, but the value used is adjusted based on the distance from poison top to top of rack.$ Conservatively, it is assumed that from top of Region 1 racks to horizontally dropped assembly is 8 inches.Holtec Report HI-2115004 4-69 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.3(b)FUEL RACK PARAMETERS AND DIMENSIONS, REGION 2 Parameter Value Cell pitch, in.Cell ID, in.Wall thickness, in.Poison pocket thickness, in.Sheathing thickness, in.Sheathing width, in Holtec Report HI-2115004 4-70 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.4(a)NON-FUEL MATERIAL COMPOSITIONS Element Nuclide Fraction MCNP ZAID [4.2.1 ]Steel (density 7.84 g/cc)0.0087562 24050.70c 0.1688553 24052.70c 0.0191468 24053.70c 0.0047661 24054.70c Mn 0.0201508 25055.70c 0.0399836 26054.70c 0.6276564 26056.70c 0.0144953 26057.70c 0.0019291 26058.70c 0.0641696 28058.70c 0.024718 28060.70c Ni 0.0010745 28061.70c 0.0034259 28062.70c 0.0008725 28064.70c Zr (density = 6.55 a/cc)0.5145 40090.70c 0.1122 40091.70c Zr 0.1715 40092.70c 0.1738 40094.70c 0.028 40096.70c Pure water (density = 1.0 g/cc)0.66659 1001.70c 0.0000767 1002.70c 0.3325233 8016.70c 0.00081 8017.70c Water with 850 ppm soluble boron (density = 1.0 g/cc)0.6662752 1001.70c 0.0000766 1002.70c 0.3323663 8016.70c 0.0008096 8017.70c 0.000094 5010.70c 0.0003783 5011.70c Water with 1350 ppm soluble boron (density = 1.0 l/cc)0.6660899 1001.70c 0.0000766 1002.70c 0.3322739 8016.70c 0.0008094 8017.70c 0.0001493 5010.70c 0.90006009 5011.70c Holtec Report HI-2 115004 4-71 Holtec Project 2119 Ho.ltec Report HI-2115004 4-71 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.4(b)NON-FUEL MATERIAL COMPOSITIONS Element .Nuclide Fraction I MCNP ZAID [4.2.1]Water with 1720 ppm soluble boron (density=
1.0 acc)0.6659527 1001.70c H 0.0000766 1002.70c 0 0.3322054 8016.70c 0.0008092 8017.70c B 0.0001902 A Anf7,<Q 5010.70c 5011.70c Holtec Report HI-2115004 4-72 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION TABLE 4.5.5 FUEL MATERIAL COMPOSITIONS Element Weight Fraction MCNP ZAID [4.2.1]Fuel enrichment of 5 wt% (density = 10.5312 g/cc)0.04408 92235.70c 0.83742 92238.70c O 0.11850 8016.70c Fresh fuel enrichment equivalent of 1.14 wt% (density = 10.5312 g/cc)0.01005 92235.70c 0.87145 92238.70c 0 0.11850 8016.70c Holtec Report 111-2115004 4-73 Holtec Project 2119 Holtec Report HI-2115004 4-73 Holtec Project 2119 Flux Trap Rack Wall _E Fuel Rod Instrumentation Tube-Guide Bar Poison Sheathing FIGURE 4.5.1 -A 2-D REPRESENTATION OF THE MCNP5-1.51 MODEL OF THE REGION 1 SFP RACKS Holtec Report HI-2 115004 4-74 Holtec Project 2119 Holtec Report HI-2115004 4-74 Holtec Project 2119 Fuel Rods Instrumentation Tube FIGURE 4.5.2 -A 2-D AXIAL REPRESENTATION OF THE SFP REGION 1 RACK MCNP5-1.51 MODEL The figure is not to scale.Holtec Report HI-2115004 4-75 Holtec Project 2119
-Sheathing Rack Wall FIGURE 4.5.3 -A PARTIAL 2-D REPRESENTATION OF NEUTRON ABSORBER LOCATION Each neutron absorber panel is centered in the gap between the cell wall and sheathing.
Holtec Report 111-2115004 4-76 Holtec Project 2119 Holtec: Report HI-2115004 4-76 Holtec Project 2119 FIGURE 4.5.4 -A 2-D REPRESENTATION OF THE MCNP5-1.51 REGION 2 RACK MODEL Holtec Report HI-2115004 4-77 Holtec Project 2119 4.6 Analysis 4.6.1 Design Basis and Uncertainty Evaluations 4.6.1.1 Design Basis Fuel Assembly As discussed in Section 4.2.3.1 and characterized in Table 4.5.1, two 5.0 wt% U-235 15x15 PWR fuel assemblies used in Palisades were analyzed.
The results are provided in Table 4.6.1, for the SFP filled with pure water, 850 ppm borated water and 1720 ppm borated water. As can be seen, the fuel assembly of Batch R and beyond is bounding and is used as the design basis fuel assembly hereafter.
4.6.1.2 Water Temperature and Density Effect 4.6.1.2.1 Region 1 SFP Racks As discussed in Section 4.2.3.2.1, the effects of water temperature, and the corresponding water density and temperature adjustments (S(ct3)) were evaluated for Region 1 racks. The results of these calculations are presented in Table 4.6.2(a), for both racks filled with pure (un-borated) and borated water.The results of the SFP temperature and density calculations show that as expected (for poisoned racks) the most reactive water temperature and density for the Region 1 racks is a temperature of 39.2 'F at a density of 1 g/cc, and these values are used for all calculations in Region 1 racks.4.6.1.2.2 Region 2 SFP Racks As discussed in Section 4.2.3.2.2, the effects of water temperature, and the corresponding water density and temperature adjustments (S(a,P3))
were evaluated for Region 2 racks. The results of these calculations are presented in Table 4.6.2(b) for pure water.Holtec Report HI-2115004 4-78 Holtec Project 2119 The results of the SFP temperature and density calculations show that as expected (for un-poisoned water) the most reactive water temperature and density for the Region 2 racks is a temperature of 150 TF at a density of 0.98026 g/cc, and these values are used for all calculations for Region 2 racks.4,6.1.3 Fuel and Rack Manufacturing Tolerances 4,6.1.3.1 Fuel Assembly Tolerances As discussed in Section 4.2.3.3.1, the reactivity effect of the PWR fuel tolerances was determined.
The results of these calculations are presented in Table 4.6.3(a) for the SFP filled with pure (un-borated), and Table 4.6.3(b) for borated water. The maximum positive delta-k value for each tolerance is statistically combined.Note that the maximum statistical combination (between the SFP with pure water and the SFP with borated water) of fuel assembly tolerances is used to determine keff.4,6.1.3.2 Region 1 Rack Tolerances As discussed in Section 4.2.3.3.2, the reactivity effect of the manufacturing tolerances of Region 1 racks with MetamicTM panels was determined.
The results of these calculations are presented in Table 4.6.4(a) for the SFP filled with pure (un-borated), and Table 4.6.4(b) for borated water.The maximum positive delta-k value for each tolerance is statistically combined.Note that the maximum statistical combination (between the SFP With pure water and the SFP with borated water) of Region 1 rack tolerances is used to determine keff.4.6.1.4 Fuel Assembly Eccentric Positioning As discussed in Section 4.2.3.4, four fuel assembly eccentric positioning cases in racks were evaluated.
The results of these calculations are presented in Table 4.6.6, for the SFP filled with Holtec Report HI-2115004 4-79 Holtec Project 2119 both pure (un-borated) and borated water. For each eccentric position case, the result for similar but centered case is also included, as a reference.
The maximum reactivity effect of the MCNP5-1.51 calculations (for both the SFP with pure water and the SFP with borated water) of fuel radial positioning is statistically combined with other uncertainties to determine keff.4.6.1.5 Assemblies with Missing Fuel Rods As discussed in Section 4.2.3.5, the effect of assemblies with missing fuel rods on reactivity in the SFP Region 1 was calculated for two scenarios.
The results for Scenario 1 are presented in Table 4.6.7(a) for pure water, and Table 4.6.7(b) for borated water. The results for Scenario 2 are presented in Table 4.6.7(c) for pure water, and Table 4.6.7(d) for borated water.The maximum positive result for Scenario 1 (from Table 4.6.7(a) and Table 4.6.7(b))
is used to determine keff. The maximum positive result for Scenario 2 (from Table 4.6.7(c) and Table 4.6.7(d))
is provided in a note to Table 4.6.8(a) and Table 4.6.8(b) as an option.4.6.1.6 MetamicTM Coupon Measurement Uncertainty As discussed in Section 4.2.3.6, the effect of MetamicTM coupon measurement uncertainty on reactivity in the Region 1 of the SFP was calculated.
The result of this calculation is presented in Table 4.6.4(a) and Table 4.6.4(b) with the other rack tolerances.
The delta-kcalc value is statistically combined with the other uncertainties.
4.6.2 Maximum kef Calculations As discussed in Section 4.2.4.1.1, the maximum keff is calculated.
The results are tabulated in Table 4.6.8(a) for pure water, and Table 4.6.8(b) for borated water. The results show that the maximum kefr for the Region 1 SFP racks is less than 1.0 at a 95% probability and at a 95% confidence Holtec Report HI-2115004 4-80 Holtec Project 2119 level without credit for soluble boron, and less than or equal to 0.95 at a 95% probability and at a 95% confidence level with credit for soluble boron.4.6.3 Margin Evaluation As discussed in Section 4.2.5, a margin analysis was performed using the nominal values for poison thickness and loading. Table 4.6.9(a) compares the reactivity of the Region 1 racks with these nominal values to the design basis Region 1 racks.As can be seen and is expected, the reactivity of design basis is larger, and provides an additional margin to the regulatory limit.Table 4.6.9(b) presents the sensitivity analysis performed to evaluate the effect of amount B 4 C loading on reactivity.
4.6.4 Fuel Movement, Inspection and Reconstitution Operations As discussed in Section 4.2.6, the fuel movement, inspection and reconstitution operation at Region 1 racks was evaluated by modeling of the bounding case of two fuel assemblies in the elevator region. The results of these calculations are presented in Table 4.6. 10 for racks with pure water.Compared to the reactivity of the reference, the results of two fuel assemblies in the elevator region calculations show that the reactivity effect of the fuel movement, inspection and reconstitution operations with the addition of the 95/95 uncertainty is positive.
However, the difference in calculated reactivity is less than 2;. Additionally, the case with fuel assemblies in the elevator region is bounded by the design basis case. Therefore, no additional calculations are required.Holtec Report HI-2115004 4-81 Holtec Project 2119 4.6.5 Interface 4.6.5.1 Region I to Region 1 Gap As discussed in Section 4.2.7.1, the reactivity effect of the minimum water gap width between two racks was evaluated.
The results of these calculations are presented in Table 4.6.5, for the SFP filled with both pure (un-borated) and borated water. As can be seen, using the minimum water gap width between two racks slightly increases the reactivity.
The 'kcalc -kcalc,reference' is added as a bias and '2 * (F calc 2 + calcreference 2 (95/95 uncertainty) is added as an uncertainty in calculating keff.4.6.5.2 Case 1: Effect of Region 1 on Reactivity of Region 2 As discussed in Section 4.2.7.2.1, the effect of Region 1 on reactivity of Region 2 was evaluated for the SFP filled with pure water. The results are presented in Table 4.6.11. _ _ _ _ _I 4.6.5.3 Case 2: Effect of Region 2 on Reactivity of Region 1 I Holtec Report HI-2115004 4-82 Holtec Project 2119 4.6.6 Abnormal and Accident Conditions 4.6.6.1 Increased Water Temperature As discussed in Section 4.2.8.1, the effect of increased temperature on reactivity was evaluated.
The results are shown in Table 4.6.14. As can be seen, the increased water temperature will not result in an increase in reactivity.
4.6.6.2 Dropped Assembly -Horizontal As discussed in Section 4.2.8.2, the effect of horizontally dropped fuel assembly on top of Region 1 racks was evaluated.
The results are provided in Table 4.6.15. As can be seen, the dropped fuel assembly may result in an increase in reactivity.
For Region 1 racks filled with borated water, the effect of this accident on reactivity is bounded by the mislocated fuel assembly at the south of inspection station, discussed in Section 4.6.6.4.1.
4.6.6.3 Dropped Assembly -Vertical into a Storage Cell As discussed in Section 4.2.8.3, the effect of vertically dropped fuel assembly into Region 1 racks was evaluated.
The results are provided in Table 4.6.16. As can be seen, with the addition of the 95/95 uncertainty the dropped fuel accident may result in a slight increase in reactivity.
The effect of this accident on reactivity is bounded by the mislocated fuel assembly at the south of inspection station, discussed in Section 4.6.6.4.1.
Noltec Report HI-2 115004 4-83 Holtec Project 2119 Holtec Report HII-2115004 4-83 Holtec Project 2119 4.6.6.4 Mislocated Fresh Fuel Assembly 4.6.6.4.1 Mislocation of a Fuel Assembly in Elevator Region As discussed in Section 4.2.8.6.1, the effect of mislocated fuel assembly in the elevator region on reactivity was evaluated for two cases. The results are provided in Table 4.6.17(a) and Table 4.6.17(b).
As can be seen, the mislocated fuel assembly in the elevator region would result in an increase in reactivity.
For Region 1 storage cells filled with borated water, the effect of the mislocated fuel assembly at the south of inspection station on reactivity is more than the other accidents.
Thus, its calculated MCNP5-1.51 kcalc is used for maximum keff calculations, discussed in Section 4.6.6.6.4.6.6.4.2 Mislocation of a Fuel Assembly in North Tilt Pit As discussed in Section 4.2.8.6.2, the mislocated fuel assembly in the north tilt pit was evaluated for two cases. The results are provided in Table 4.6.18(a) and Table 4.6.18(b).
As can be seen, the mislocated fuel assembly in the north tilt pit may result in an increase in reactivity.
The effect of this accident on reactivity is bounded by the mislocated fuel assembly at the south of inspection station, discussed in Section 4.6.6.4.1.
4.6.6.5 Rack Movement As discussed in Section 4.2.8.8, the Region 1 rack movement was evaluated, and the results were compared to its corresponding reference case. The result is provided in Table 4.6.19. As can be seen, the Region 1 rack movement would result in increase in reactivity.
The effect of this accident on reactivity is bounded by the mislocated fuel assembly at the south of inspection station, discussed in Section 4.6.6.4.1.
Holtec Report HI-2115004 4-84 Holtec Project 2119 4.6.6.6 Maximum keff during Accident Condition As discussed in Section 4.2.8, the maximum keff of all credible accident conditions was calculated.
The results are tabulated in Table 4.6.20. The results show that the maximum keff is less than or equal to 0.95 at a 95% probability and at a 95% confidence level with credit for soluble boron.Holtec Report 111-2115004 4-85 Holtec Project 2119 Holtec Report HI-2115004 4-85 Holtec Project 2119 TABLE 4.6.1 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE DESIGN BASIS FUEL ASSEMBLY CALCULATIONS Description kcalc a delta-kcalc Pure water
 
==Reference:==
 
Fuel assembly of Batch R 0.9475 0.0004 Reference and beyond 0.9475 0.0004 Reference Fuel assembly before Batch R 0.9439 0.0004 -0.0025 850 ppm borated water
 
==Reference:==
 
Fuel assembly of Batch R and beyond 0.8712 0.0004 Reference Fuel assembly before Batch R 0.8637 0.0004 -0.0064 1720 ppm borated water
 
==Reference:==
 
Fuel assembly of Batch R 0.8084 0.0004 Reference and beyond Fuel assembly before Batch R 0.7990 0.0004 -0.0083 Holtec Report HI-2 115004 4-86 Holtec Project 2119 Holtec Report HI-2115004 4-86 Holtec Project 2119 TABLE 4.6.2(a)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF WATER TEMPERATURE AND DENSITY IN REGION 1 Water Water Temperature Temperature Density Adjustment, kcaic -Description S(a,3) kcalc kcalc,reference (OF) (g/cc) (OF)Region 1 -pure water
 
==Reference:==
 
lower 39.2 1 68.81 0.9475 0.0004 Reference bound temperature Like the reference case, but with no 39.2 1 N/A 0.9420 0.0004 -0.0055 S(a,p3) card Upper bound temperature for 150 0.98026 68.81 0.9417 0.0004 -0.0058 normal operation, low S(ap3)Upper bound temperature for nomperation 150 0.98026 170.33 0.9410 0.0004 -0.0065 normal operation, high S(a,p)Region 1 -1720 ppm borated water
 
==Reference:==
 
lower 39.2 1 68.81 0.8084 0.0004 Reference bound temperature Like the reference case, but with no 39.2 1 N/A 0.8050 0.0004 -0.0034 S(ap3) card Upper bound temperature for 150 0.98026 68.81 0.8063 0.0004 -0.0021 normal operation, low S(a,p3)Upper bound temperature for nomperation 150 0.98026 170.33 0.8062 0.0003 -0.0022 normal operation, high S(a,p) I I Holtec Report HI-2 115004 4-87 Holtec Project 2119 TABLE 4.6.2(b)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF WATER TEMPERATURE AND DENSITY ON REACTIVITY IN REGION 2 Water Water Temperature Description Temperature Density Adjustment, kcaic kcalc -S(a,1) kcalc,reference (OF) (g/cc) (OF)Region 2 -pure water Lower bound 39.2 1 68.81 0.9699 0.0002 -0.0025 temperature Upper bound temperature for nomperation 150 0.98026 68.81 0.9709 0.0002 -0.0015 normal operation, low S(a,p)
 
==Reference:==
 
upper bound temperature 150 0.98026 170.33 0.9724 0.0002 Reference for normal operation, high S(a,p)Holtec Report HI-2115004 4-88 Holtec Project 2119 TABLE 4.6.3(a)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR FUEL TOLERANCES AT REGION 1 SFP RACKS WITH PURE WATER Description kcalc a delta-kcaIc
 
==Reference:==
 
design basis fuel 0.9475 0.0004 Reference Max pellet density 0.9486 0.0004 0.0022 Min pellet density 0.9469 0.0004 0.0005 Max clad OD 0.9448 0.0004 -0.0016 Min clad OD 0.9499 0.0004 0.0035 Max clad ID 0.9472 0.0004 0.0008 Min clad ID 0.9470 0.0004 0.0006 Max pellet diameter 0.9483 0.0005 0.0021 Min pellet diameter 0.9482 0.0004 0.0018 Max rod pitch 0.9495 0.0004 0.0031 Max instrumentation tube OD 0.9482 0.0003 0.0017 Min instrumentation tube OD -0.9473 0.0004 0.0009 Max instrumentation tube ID 0.9469 0.0004 0.0005 Min instrumentation tube ID 0.9478 0.0004 0.0014 Max guide bar OD 0.9476 0.0004 0.0012 Min guide bar OD 0.9477 0.0003 0.0012 Statistical Combination 0.0062 Note 1: For each fuel variable, the tolerance (either upper limit or bottom limit) which results in the larger positive delta-kcalc is considered in calculating the statistical combination.
Holtec Report HI-2115004 4-89 Holtec Project 2119 TABLE 4.6.3(b)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR FUEL TOLERANCES AT REGION 1 SFP RACKS WITH 1720 PPM BORATED WATER Description kcalc Y delta-kcalc
 
==Reference:==
 
design basis fuel 0.8084 0.0004 Reference Max pellet density 0.8106 0.0004 0.0033 Min pellet density 0.8079 0.0004 0.0006 Max clad OD 0.8072 0.0004 -0.0001 Min clad OD 0.8105 0.0004 0.0032 Max clad ID 0.8088 0.0004 0.0015 Min clad ID 0.8086 0.0003 0.0012 Max pellet diameter 0.8093 0.0004 0.0020 Min pellet diameter 0.8085 0.0004 0.0012 Max rod pitch 0.8095 0.0004 0:0022 Max instrumentation tube OD 0.8078 0.0003 0.0004 Min instrumentation tube OD 0.8087 0.0004 0.0014 Max instrumentation tube ID 0.8077 0.0006 0.0007 Min instrumentation tube ID 0.8084 0.0004 0.0011 Max guide bar OD 0.8088 0.0004 0.0015 Min guide bar OD 0.8081 0.0003 0.0007 Statistical Combination 0.0062 Note 1: For each fuel variable, the tolerance (either upper limit or lower limit) which. results in the larger positive delta-kcalc is considered in calculating the statistical combination.
Holtec Report HI-2115004 4-9.0 Holtec Project 2119 TABLE 4.6.4(a)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR RACK TOLERANCES AT REGION 1 SFP WITH PURE WATER Description kcalc o delta-kcali Reference 0.9475 0.0004 Reference Max cell ID 0.9531 0.0004 0.0067 Min cell ID 0.9422 0.0004 -0.0042 Max cell pitch
* 0.9386 0.0005 -0.0076 Min cell pitch
* 0.9576 0.0004 0.0112 Min poison pocket thickness 0.9467 0.0005 0.0005 Min sheathing thickness 0.9472 0.0005 0.0010 Max sheathing thickness 0.9462 0.0005 0.0000 MetamicTM coupon 0.9497 0.0004 0.0033 measurement uncertainty Statistical Combination 0.0136 The max/min pitch tolerance effectively decreases/increases the flux trap.Note 1: For each rack variable, the tolerance (either upper limit or lower limit) which results in the larger positive delta-kcalc is considered in calculating the statistical combination.
Holtec Report 111-2115004 4-91 1-loltec Project 2119 Holtec Report HI-2115004 4-91 Holtec Project 2119 TABLE 4.6.4(b)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE RACK TOLERANCES AT REGION 1 SFP WITH 1720 PPM BORATED WATER Description kcalc a delta-kcalc Reference 0.8084 0.0004 Reference Max cell ID 0.8119 0.0004 0.0046 Min cell ID 0.8044 0.0003 -0.0030 Max cell pitch t 0.8001 0.0005 -0.0070 Min cell pitch 1 0.8168 0.0004 0.0095 Min poison pocket thickness 0.8076 0.0004 0.0003 Min sheathing thickness 0.8075 0.0004 0.0002 Max sheathing thickness 0.8078 0.0004 0.0005 MetamicTM coupon 0.8099 0.0004 0.0026 measurement uncertainty Statistical Combination 0.0109 The max/min pitch tolerance effectively decreases/increases the flux trap.Note 1: For each rack variable, the tolerance (either upper limit or bottom limit) which results in the larger positive delta-kcalc is considered in calculating the statistical combination.
Holtec Report HI-2115004 Holtec Report HI-2 115004 4-92 Holtec Project 2119 4-92 Holtec Project 2119 TABLE 4.6.5 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE MINIMUM WATER GAP WIDTH BETWEEN REGION 1 RACKS Description kcaic kcalc -kcalc,reference 95/95 Uncertainty Pure water I I Holtec Report HI-2115004 4-93 Holtec Project 2119 TABLE 4.6.6 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR ECCENTRIC POSITIONING IN REGION 1 SFP Description kcalc CF -[delta-kcalc Pure water
 
==Reference:==
 
design basis 0.9475 0.0004 Reference Eccentric assemblies, 2x2 cells 0.9459 0.0004 -0.0005 toward outside Eccentric assemblies, 2x2 cells 0.946 0.0004 -0.0004 toward center Eccentric assemblies, full rack array 0.9457 0.0004 -0.0007 toward outside Eccentric assemblies, full rack array 0.9467 0.0004 0.0003 toward center 1720 ppm borated water
 
==Reference:==
 
design basis 0.8084 0.0004 Reference Eccentric assemblies, 2x2 cells 0.8022 0.0004 -0.0051 toward outside Eccentric assemblies, 2x2 cells 0.8036 0.0004 -0.0037 Eccentric assemblies, full rack array 0.8029 0.0004 -0.0044 toward outside Eccentric assemblies, full rack array 0.8025 0.0004 -0.0048 toward center Holtec Report 111-2115004 4-94 Holtec Project 2119 Holtec Report HI-2115004
'4-94 Holtec Project 2119 TABLE 4.6.7(a)RESULTS OF THE.MCNP5-1.51 CALCULATION SCENARIO 1 FOR A 3X3 ARRAY MODEL, WITH A FUEL ASSEMBLY WITH MISSING 4 FUEL RODS FROM THE CELL IN THE CENTER Description kcalc kcalc -95/95 kcalc,reference Uncertainty Pure water
 
==Reference:==
 
design basis 0.9475 0.0004 Reference Reference Missing 4 fuel rods in A-I, A-15, 0-1 and 0-15 0.9467 0.0004 -0.0008 0.0011 Missing 4 fuel rods in C-3, C-13, M-3 and M-13 0.9477 0.0004 0.0002 0.0011 Missing 4 fuel rods in D-4, D-12, L-4 and L-12 0.9487 0.0004 0.0012 0.0011 Missing 4 fuel rods in E-5, E- 11, K-5 and K-11 0.9481 0.0004 0.0006 0.0011 Missing 4 fuel rods in F-6, F-10, J-6 and J-10 0.9479 0.0004 0.0004 0.0011 Missing 4 fuel rods in G-7, G-9, 1-7 and 1-9 0.9482 0.0004 0.0007 0.0011 Missing 4 fuel rods in A-8, H-i, H-15 andO-8 0.9470 0.0004 -0.0005 0.0011 Missing 4 fuel rods in C-8, H-3, H-13 and M-8 0.9481 0.0004 0.0006 0.0011 Missing 4 fuel rods in E-8, H-5, H- 11 and K-8 0.9479 0.0004 0.0004 0.0011 Missing 4 fuel rods in G-8, H-7, H-9 and 1-8 0.9478 0.0005 0.0003 0.0013 Missing 4 fuel rods, in E-5, F-6, J-10 and K- 11 0.9483 0.0004 0.0008 0.0011 Missing 4 fuel rods, in C-3, D-4, L-12 and M-13 0.9491 0.0004 0.0016 0.0011 Missing 4 fuel rods, in C-3, E-5, K-1I and M-13 0.9483 0.0004 0.0008 0.0011 Missing 4 fuel rods, in F-6, G-7, 1-9 and J-10 0.9484 0.0004 0.0009 0.0011 Holtec Report HI-2115004 4-95 Holtec Project 2119 TABLE 4.6.7(b)RESULTS OF THE MCNP5-1.51 CALCULATION SCENARIO 1 FOR A 3X3 ARRAY MODEL, WITH A FUEL ASSEMBLY WITH MISSING 4 FUEL RODS FROM THE CELL IN THE CENTER Description 850 ppm borated water
 
==Reference:==
 
design basis 0.8712 0.0004 Reference Reference Missing 4 fuel rods in A-i, A-15, 0-1 and 0-15 0.8703 0.0004 -0.0009 0.0011 Missing 4 fuel rods in C-3, C-13, M-3 and M-13 0.8707 0.0004 -0.0005 "0.0011 Missing 4 fuel rods in D-4, D-12, L-4 and L-12 0.8712 0.0004 0.0000 0.0011 Missing 4 fuel rods in E-5, E- 11, K-5 and K-11 .0.8714 0.0005 0.0002 0.0013 Missing 4 fuel rods in F-6, F-10, J-6 and J-10 0.8723 0.0004 0.0011 0.0011 Missing 4 fuel rods in G-7, G-9, 1-7 and 1-9 0.8718 0.0004 0.0006 0.0011 Missing 4 fuel rods in A-8, H-i, H-15 andO-8 0.8704 0.0004 -0.0008 0.0011 Missing 4 fuel rods in C-8, H-3, H-13 and M-8 0.8710 0.0004 -0.0002 0.0011 Missing 4 fuel rods in E-8, H-5, H-i1 and K-8 0.8708 0.0004 -0.0004 0.0011 Missing 4 fuel rods in G-8, H-7, H-9 and 1-8 0.8701 0.0004 -0.0011 0.0011 Missing 4 fuel rods, in E-5, F-6, J-10 and K-11 0.8704 0.0004 -0.0008 0.0011 Missing 4 fuel rods, in C-3, D-4, L-12 and M-13 0.8708 0.0004 -0.0004 0.0011 Missing 4 fuel rods, in C-3, E-5, K-Il and M-13 0.8712 0.0004 0.0000 0.0011 Missing 4 fuel rods, in F-6, G-7, 1-9 and J-10 0.8707 0.0004 -0.0005 0.0011 Holtec Report HI-2 115004 4-96 Holtec Project 2119 Holtec Report HI-2115004 4-96 Holte6 Proj ect 2119 TABLE 4.6.7(c)RESULTS OF THE MCNP5-1.51 CALCULATION SCENARIO 2 FOR A SINGLE CELL MODEL, WITH A FUEL ASSEMBLY WITH MISSING 4 FUEL RODS I I kcaic -95/95 Description Ikcal-- or ( r ,f 59 kkcac,reference Uncertainty Pure water
 
==Reference:==
 
design basis 0.9475 0.0004 Reference Reference Missing 4 fuel rods in A-I, A-15, 0-1 and 0-15 0.9383 0.0004 -0.0092 0.0011 Missing 4 fuel rods in C-3, C-13, M-3 and M-13 0.9513 0.0004 0.0038 0.0011 Missing 4 fuel rods in E-5, E-I 1, K-5 and K-11 0.9541 0.0004 0.0066 0.0011 Missing 4 fuel rods in G-7, G-9, 1-7 and 1-9 0.9551 0.0004 0.0076 0.0011 Missing 4 fuel rods in A-8, H-I, H-15 andO-8 0.9457 0.0004 -0.0018 0.0011 Missing 4 fuel rods in C-8, H-3, H-13 and M-8 0.9523 0.0004 0.0048 0.0011 Missing 4 fuel rods in E-8, H-5, H- 11 and K-8 0.9542 0.0004 0.0067 0.0011 Missing 4 fuel rods in G-8, H-7, H-9 and 1-8 0.9520 0.0005 0.0045 0.0013 Missing 4 fuel rods, in E-5, F-6, J-10 and K-11 0.9544 0.0004 0.0069 0.0011 Holtec Report HI-2115004 4-97 Holtec Project 2119 TABLE 4.6.7(d)RESULTS OF THE MCNP5-1.51 CALCULATION SCENARIO 2 FOR A SINGLE CELL MODEL, WITH A FUEL ASSEMBLY WITH MISSING 4 FUEL RODS Description 850 ppm borated water
 
==Reference:==
 
design basis 0.8712 0.0004 Reference Reference Missing 4 fuel rods in A-i, A-15, 0-1 and 0-15 0.8621 0.0004 -0.0091 0.0011 Missing 4 fuel rods in C-3, C-13, M-3 and M-13 0.8721. 0.0004 0.0009 0.0011 Missing 4 fuel rods in E-5, E-1 1, K-5 and K-11 0.8728 0.0004 0.0016 0.0011 Missing 4 fuel rods in G-7, G-9, 1-7 and 1-9 0.8721 0.0004 0.0009 0.0011 Missing 4 fuel rods in A-8, H-i, H-15 andO-8 0.8679 0.0004 -0.0033 0.0011 Missing 4 fuel rods in C-8, H-3, H-13 and M-8 0.8731 0.0004 0.0019 0.0011 Missing 4 fuel rods in E-8, H-5, H-11 and K-8 0.8729 0.0004 0.0017 0.0011 Missing 4 fuel rods in G-8, H-7, H-9 and 1-8 0.8685 0.0004 -0.0027 0.0011 Missing 4 fuel rods, in E-5, F-6, J-10 and K-11 0.8707 0.0004 -0.0005 0.0011 Holtec Report HI-2115004 4-98 Holtec Project 2119 TABLE 4.6.8(a)MAXIMUM keff CALCULATION FOR REGION 1 SFP WITH PURE WATER Parameter Value Uncertainties Uncertainty of fuel tolerances, from Table 4.6.3(a) 0.0062 Uncertainty of rack tolerances, from Table 4.6.4(a) 0.0136 Uncertainty of rack to rack bias, from Table 4.6.5 0.0016 Uncertainty of eccentric positioning, from Table 4.6.6 0.0003 Uncertainty of missing 4 fuel-rods (for one fuel out of 9) bias, from Table 0.0013 4.6.7(a)MCNP5-1.51 bias calculation uncertainty (95%/95%)
for pure water, from Table 0.0068 4.2.1(d) 0.0068 MCNP5-1.51 calculations statistics (95%/95%, 2a), from Tables 4.6.3(a), 0.0012 4.6.4(a) and 4.6.6 Statistical combination of uncertainties 0.0166 Calculated MCNP5-1.51 kcaic, from Table 4.6.1 0.9475 Calculation MCNP5-1.51 bias for pure water, from Table 4.2. 1(d) 0.0000 Rack to rack bias, from Table 4.6.5 0.0152 Missing 4 fuel-rods bias (for one fuel out of 9), from Table 4.6.7(a) 0.0016 Maximum keff 0.9809 Regulatory Limit 1.0000 Note 1: If every fuel assembly in the SFP Region 1 rack would have 4 missing fuel rods, the maximum keff would be 0.9869.Holtec Report HI-2115004 4-99 Holtec Project 2119 TABLE 4.6.8(b)MAXIMUM keff CALCULATION FOR REGION 1 SFP WITH 850 PPM BORATED WATER Parameter Value Uncertainties Uncertainty of fuel tolerances, from Table 4.6.3(a) 0.0062 Uncertainty of rack tolerances, from Table 4.6.4(a) 0.0136 Uncertainty of rack to rack bias, from Table 4.6.5 0.0016 Uncertainty of eccentric positioning, from Table 4.6.6 0.0003 Uncertainty of missing 4 fuel-rods (for one fuel out of 9) bias, from Table 0.0013 4.6.7(b)MCNP5-1.51 bias calculation uncertainty (95%/95%)
for borated water from 0.0078 Table 4.2.1 (e) 0.0078 MCNP5-1.51 calculations statistics (95%/95%, 2a), from Tables 4.6.3(a), 0.0012 4.6.4(a) and 4.6.6 Statistical combination of uncertainties 0.0170 Calculated MCNP5-1.51 kcaic, from Table 4.6.1 0.8712 Calculation MCNP5-1.51 bias for borated water, from Table 4.2.1 (e) 0.0023 Rack to rack bias, from Table 4.6.5 0.0152 Missing 4 fuel-rods bias (for one fuel out of 9), from Table 4.6.7(b) 0.0011 Maximum keff 0.9068 Regulatory Limit 0.9500 Note 1: If every fuel assembly in the SFP Region 1 rack would have 4 missing fuel rods, the maximum keff would be 0.9076.Holtec Report HI-2115004 4-100 Holtec Project 2119 TABLE 4.6.9(a)MARGIN ANALYSIS, RESULTS OF THE MCNP5-1.51 CALCULATIONS TO EVALUATE THE EFFECT OF USING MINIMUM B 4 C LOADING AND MINIMUM METAMIC T M PANEL THICKNESS, INSTEAD OF NOMINAL VALUES ON REACTIVITY B 4 C B-10 Areal Loading Density Density kcalc -Description Ld Denit kcac CF kcalcreference
(%) (gN/cm2) (g/cm 3)Pure water
 
==Reference:==
 
model of Region 1 'rack with minimum values for .......0 475 .000.Refrenc B 4 C loading and MetamicTM 0.9475 0.0004 Reference panel thickness (design basis) j., 7, Rack with nominal values for B 4 C loading and Metamic T M  1 0.9440 0.0004 -0.0035 panel thickness 850 ppm borated water
 
==Reference:==
 
model of Region 1 rack with minimum values for <',A <,
,' $7<1 0.8712 0.0004 Reference B 4 C loading and MetamicTM 0.8712 0..... Reference panel thickness (design basis) '? , "': 'Rack with nominal values for , :"/m ". ' -.< "'7," B 4 C loading and Metamic T M  ' 0.8690 0.0004 -0.0022 panel thickness I I Holtec Report HI-2115004 4-101 Holtec Project 2119 TABLE 4.6.9(b)MARGIN ANALYSIS, RESULTS OF THE MCNP5-1.51 SENSITIVITY ANALYSIS TO EVALUATE THE CHANGE IN SFP REACTIVITY AS A FUNCTION OF B 4 C LOADING
 
==Reference:==
 
model of Region 1 rack with minimum values for B 4 C loading and MetamicTM panel thickness (design basis)I1 Same as the reference, except with L_- B 4 C loading.0.9475 0.0004 Reference 0.9497 0.0004 0.0022 0.9522 0.0004 0.0047 0.9541 0.0004 0.0066 Same as the reference, except with loading Same as the reference, except with loading Holtec Report HI-2115004 4-102 Holtec Project 2119 .
TABLE 4.6.10 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF TWO FUEL ASSEMBLIES IN THE ELEVATOR REGION ON REACTIVITY OF REGION 1 RACKS Description kcalc G delta-kcalc Pure water Design basis 0.9475 0.0004 N/A
 
==Reference:==
 
model of Region 1 rack with no 0.9435 0.0004 Reference fuel assembly in the fuel elevator region Model of Region 1 rack with two fuel 0.9451 0.0004 0.0027 assemblies in the fuel elevator region I I Holtec Report HI-2115004 4-103 Holtec Project 2119 TABLE 4.6.11 RESULTS OF THE MCNP5-1.51 INTERFACE CALCULATIONS Description I kcalc I a I delta-kcalc Holtec Report HI-21 15004 4-104 Holtec Project 2119 Holtec Report HI-2115004 4-104 Holtec Project 2119 TABLE 4.6.12(a)RESULTS OF THE MCNP5-1.51 INTERFACE CALCULATIONS Holtec Report HI-2115004 4-105 Holtec Project 2119 TABLE 4.6.12(b)RESULTS OF THE MCNP5-1.51 INTERFACE CALCULATIONS Holtec Report HI-2115004 4-106 Holtec Project 2119 Holtec Report HI-2115004 4-107 Holtec Project 2119 TABLE 4.6.14 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF INCREASED WATER TEMPERATURE ON REACTIVITY OF SFP WITH PURE WATER Water Water Temperature Description Temp. Density Adjustment, SD(poOO) kcalc aY delta-kcalc (OF) (g/cc) (OF)
 
==Reference:==
 
lower bound temperature (design 39.2 1 68.81 0.9475 0.0004 Reference basis)Upper bound temperature for accident 255 0.84591 260.33 0.9011 0.0005 -0.0451 condition I I I Holtec Report HI-2115004 4-108 Holtec Project 2119 TABLE 4.6.15 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF HORIZONTALLY DROPPED FUEL ASSEMBLY Description kcalc G delta-kcalc Pure water
 
==Reference:==
 
design basis 0.9475 0.0004 1 Reference Region 1 racks Reyion 1 -ter I Horizontally dropped fuel assembly on top of Region 1 racks Holtec Report HI-2115004 4-109 Holtec.Project 2119 TABLE 4.6.16 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF VERTICALLY DROPPED FUEL ASSEMBLY INTO A STORAGE CELL Description kcalc Y delta-kcalc Pure water
 
==Reference:==
 
design basis 0.9475 0.0004 Reference Vertically dropped fuel 0.9477 0.0004 0.0013 assembly into an empty cell Region 1 -1350 ppm borated water Vertically dropped fuel 0 assembly into an empty cell Holtec Report HI-2115004 4-110 Holtec Project 2119 TABLE 4.6.17(a)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF MISLOCATED FUEL ASSEMBLY IN ELEVATOR REGION (MISLOCATED FUEL ASSEMBLY IS IN THE CORNER OF THE ELEVATOR REGION)Description kcalc a delta-kcalc Pure water
 
==Reference:==
 
no mislocated assembly 0.9451 0.0004 Reference Mislocated fuel assembly in the 0.9961 0.0004 0.0521 comer of elevator region Region 1 -1350 ppm borated water Mislocated fuel assembly in the 56 comer of elevator region 1 Holtec Report 141-2115004 4-111 Holtec Project 2119 Holtec Report HI-2115004 4-111 Holtec Project 2119 TABLE 4.6.17(b)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF MISLOCATED FUEL ASSEMBLY IN ELEVATOR REGION (MISLOCATED FUEL ASSEMBLY IS AT THE SOUTH OF THE INSPECTION STATION)Description kcalc a delta-kcalc Pure water
 
==Reference:==
 
no mislocated assembly 0.9451 0.0004 Reference Mislocated fuel assembly at the 1.0437 0.0004 0.0997 south of inspection station Region 1 -1350 ppm borated water Mislocated fuel assembly at the 0.8666 0.0004 N/A south of inspection station I I I Holtec Report HI-2115004 4-112 Holtec Project 2119 TABLE 4.6.18(a)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF MISLOCATED FUEL ASSEMBLY IN NORTH TILT PIT (MISLOCATED FUEL ASSEMBLY RODS ARE LINED UP WITH FUEL RODS IN REGION 1 RACK)Description kca1c u delta-kcalc Pure water
 
==Reference:==
 
no mislocated assembly 0.9644 0.0002 N/A Mislocated fuel assembly between Regions 1 0.9954 0.0004 0.0319 and 2 racks in North Tilt Pit Region 1 -1350 ppm borated water Mislocated fuel assembly between Regions 1 0.8340 0.0004 N/A and 2 racks in North Tilt Pit Holtec Report HI-2115004 4-113 Holtec Project 2119 TABLE 4.6.18(b)RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF MISLOCATED FUEL ASSEMBLY IN NORTH TILT PIT (MISLOCATED FUEL ASSEMBLY RODS ARE LINED UP WITH FUEL RODS IN REGION 2 RACK)Description kca.c a delta-kcalc Pure water
 
==Reference:==
 
no mislocated assembly 0.9644 0.0002 Reference Mislocated fuel assembly between Regions 1 0.9961 0.0003 0.0324 and 2 racks in North Tilt Pit Region 1 -1350 ppm borated water Mislocated fuel assembly between Regions 1 0.8329 0.0003 N/A and 2 racks in North Tilt Pit Holtec Report HI-2115004 4-114 Holtec Project 2119 TABLE 4.6.19 RESULTS OF THE MCNP5-1.51 CALCULATIONS FOR THE EFFECT OF REGION 1 RACK MOVEMENT Description kcalc a delta-kaic Pure water
 
==Reference:==
 
no rack movement 0.9627 0.0007 Reference No water gap between Region 1 racks 0.9691 0.0007 0.0084 Region 1 -1350 ppm borated water No water gap between Region 1 racks 0.8520 0.0008 N/A Holtec Report HI-2115004 4-115 Holtec Project 2119 TABLE 4.6.20 MAXIMUM keff CALCULATION FOR REGION 1 SFP FILLED WITH 1350 PPM BORATED WATER DURING ACCIDENT CONDITION Parameter Value Uncertainties Uncertainty of fuel tolerances, from Table 4.6.3(a) 0.0062 Uncertainty of rack tolerances, from Table 4.6.4(a) 0.0136 Uncertainty of rack to rack bias, from Table 4.6.5 0.0016 Uncertainty of eccentric positioning, from Table 4.6.6 0.0003 Uncertainty of missing 4 fuel-rods (for one fuel out of 9) bias, from 0.0013 Table 4.6.7(b)MCNP5-1.51 bias calculation uncertainty (95%/95%)
for borated 0.0078 water, from Table 4.2.1 (e)MCNP5-1.51 calculations statistics (95%/95%, 2y), from Tables 0.0012 4..3(a), 4.6.4(a) and 4.6.6 Statistical combination of uncertainties 0.0170 Maximum Calculated MCNP5-1.51 kcalc, from Tables 4.6.15, 0.8666 4.6.16, 4.6.17, 4.6.18 and 4.6.19 Calculation MCNP5-1.51 bias for borated water, from Table 4.2.1(e)Rack to rack bias, from Table 4.6.5 0.0152 Missing 4 fuel-rods bias (for one fuel out of 9), from Table 4.6.7(b) 0.0011 Maximum keff 0.9022 Regulatory Limit 0.9500 Note 1: If every fuel assembly in the SFP Region 1 rack would have 4 missing fuel rods, the maximum keff would be 0.9030.Holtec Report HI-2115004 4-116 Holtec Project 2119
 
===4.7 Conclusion===
The criticality analysis for the storage of fresh 15x15 PWR assemblies with an initial U-235 enrichment of up to 5.0 wt% in the Holtec storage racks at Palisades has been performed.
The results show that keff is less than 1.0 for the Region 1 SFP racks fully loaded with fuel of the highest anticipated reactivity and the pool flooded with un-borated water at a temperature corresponding to the highest reactivity.
In addition, the keff is less than 0.95 with the storage racks fully loaded with fuel of the highest anticipated reactivity and the pool flooded with borated water at a temperature corresponding to the highest reactivity.
The maximum calculated reactivity includes a margin for uncertainty in reactivity calculations with a 95% probability at a 95% confidence level. Reactivity effects of abnormal and accident conditions have also been evaluated to assure that under all credible abnormal and accident conditions, the reactivity will not exceed the regulatory limit of 0.95 with credit for soluble boron.Holtec Report HI-2115004 4-117 Holtec Project 2119
 
===4.8 References===
[4.2.1] "MCNP -A General Monte Carlo N-Particle Transport Code, Version 5," Los Alamos National Laboratory, LA-UR-03-1987, April 24, 2003 (Revised 2/1/2008).
[4.2.2] "Nuclear Group Computer Code Benchmark Calculations," Holtec Report HI-2104790 Revision 1.[4.2.3] Guide for Validation of Nuclear Criticality Safety Calculational Methodology, NUREG/CR-6698, January 2001.[4.2.4] L.I. Kopp, "Guidance on the Regulatory Requirements for Criticality Analysis of Fuel Storage at Light-Water Reactor Power Plants," NRC Memorandum from L. Kopp to T. Collins, August 19, 1998.[4.2.5] Staff Guidance Regarding the Nuclear Criticality Safety Pools, DSS-ISG-2010-01, Revision 0.[4.2.6] "License Amendment Request for Spent Fuel Pool Region 002, January 31, 2011.Analysis for Spent Fuel 1 Criticality," PNP 2011-Holtec Report HI-2115004 4-118 Holtec Project 2119 CHAPTER 5: THERMAL-HYDRAULIC EVALUATION
 
===5.1 Introduction===
Both the Palisades main SFP and the North Tilt Pit are currently equipped with spent fuel storage racks, each containing Region 1 racks with inter-cell flux traps (capable of holding either used or fresh fuel assemblies) and Region 2 racks without flux traps (only capable of holding used fuel assemblies).
The Region 1 racks contain the neutron absorbing material Carborundum, which is degraded.
The Region 1 racks are to be replaced.
The replacement of the Region 1 racks will entail removing all such racks and installing new racks having the same storage capacities and approximately the same physical dimensions.
Although the total number of storage locations for fuel assemblies will not change, the new racks are not identical to the racks being replaced and as a result the thermal-hydraulic performance of the proposed new rack arrays must be evaluated.
This chapter provides a summary of the methods, models, analyses and numerical results to demonstrate that the Palisades SFP fuel storage rack arrays meet the thermal-hydraulic requirements for safe storage of spent fuel set forth in Section 5.2 herein. Similar thermal-hydraulic analyses have been used in spent fuel storage licensing applications at many nuclear power plants (see Table 5.1.1 for a partial list).The following specific thermal-hydraulic analyses are performed for the Palisades spent fuel storage racks: 1. Calculation of the spent fuel decay heat. The decay heat contributions from both previously discharged and recently offloaded fuel assemblies are considered.
: 2. Determination of the SFP bulk thermal response versus time for each of the plant's design-basis fuel offload scenarios.
If necessary to yield peak bulk temperatures below the plant's licensing-basis limits for a given scenario, a required in-core hold time in excess of the minimum possible hold time is determined.
: 3. Calculation of the minimum time-to-boil during a postulated loss of forced cooling event for each design-basis fuel offload scenario.Holtec Report HI-2115004 5-1 Holtec Project 2119
: 4. A rigorous Computational Fluid Dynamics (CFD) based study to conservatively quantify the peak local temperature in the SFP water for the limiting design-basis fuel offload scenario.5. Determination of a bounding maximum fuel cladding temperature for the limiting design-basis fuel offload scenario.These analyses are described in detail in Sections 5.4 through 5.6. The following design-basis fuel offload scenarios are postulated and analyzed: Refueling Batch Offload -Scenario 1 The highest-heat refueling batch (a maximum of 76 fuel assemblies) is offloaded into the SFP at the end of a normal operating cycle. The heat load from this recently offloaded batch and the background heat load from all previous discharges (820 assemblies from 11 previous operating cycles, for a total of 896 assemblies from 12 operating cycles) are removed by one SFP pump and one SFP heat exchanger (the second pump and heat exchanger are assumed inoperable as a limiting single active failure).Abnormal Full Core Offload -Scenario 2 The full core (204 fuel assemblies) is offloaded into the SFP at the end of a normal operating cycle. The heat load from this recently offloaded core and the background heat load from previous discharges (692 assemblies from 10 previous operating cycles, for a total of 896 assemblies from 11 operating cycles) are removed by one SFP pump and one SFP heat exchanger (the second pump and heat exchanger are assumed inoperable as a limiting single active failure).In the sections that follow, analysis methods are described, results are presented and refueling scenarios are evaluated.
Holtec Report HI-2 115004 5-2 Holtec Project 2119 Holtec Report HI-2115004 5-2 Holtec Project 2119 Table 5.1.1 PARTIAL LISTING OF RERACK APPLICATIONS USING SIMILAR METHODS OF THERMAL-HYDRAULIC ANALYSIS PLANT USNRC DOCKET NO.Arkansas Nuclear One Unit 1 50-313 Arkansas Nuclear One Unit 2 50-368 Beaver Valley Unit 2 50-412 Clinton 50-461 Cooper 50-298 Diablo Canyon Unit 1 50-275 Diablo Canyon Unit 2 50-323 Pilgrim Unit 1 50-293 Saint Lucie Unit 1 50-335 Saint Lucie Unit 2 50-389 Shearon Harris Unit 1 50-400 Three Mile Island Unit 1 50-289'Turkey Point Unit 3 50-250 Turkey Point Unit 4 50-251 Holtec Report HI-2 115004 5-3 Holtec Project 2119 Holtec Report HI-2115004 5-3 Holtec Project 2119 5.2 Acceptance Criteria Applicable codes, standards and regulations include the following:
: a. NUREG-0800, Standard Review Plan, Section 9.1.3, Revision 1.b. USNRC OT Position Paper for. Review and Acceptance of Spent Fuel Storage and Handling Application, 4/78 [5.2.1].The design of the spent fuel storage rack modules must ensure that all fuel assemblies in the SFP are adequately cooled by natural circulation of water for the design-basis offload scenarios.
The Palisades SFP storage is evaluated to the following criteria: 1. During any fuel offload scenario with forced cooling available, the bulk pool temperature shall be limited to 150'F including the effects of a limiting single active component failure.2. Under a complete failure of active cooling during any normal fuel offload scenario, the water surface is allowed to reach saturation.
Sufficient time must be available before the onset of bulk boiling to implement corrective measures.3. During any normal fuel offload scenario, local water and fuel cladding temperatures for the fuel assemblies within the spent fuel storage racks shall not exceed the local saturation temperature, including the effects of a limiting single-active component failure.Holtec Report HI-2 115004 5-4 1-loltec Project 2119 Holtec Report HI-2115004 5-4 Holtec Project 2119 5.3 Descrintion of Snent Fuel Pool Coolina System The Palisades SFP cooling system is designed to remove the decay heat produced by spent fuel assemblies in the SFP during and following a unit refueling, including the decay heat from accumulated fuel from previous discharges.
The system incorporates two 100% capacity pumps and two 100% capacity heat exchangers designed to maintain the SFP at or below 150'F with component cooling water (CCW) supply at 90'F under refueling conditions, and associated piping, valves, and instrumentation.
The SFP cooling system heat exchangers are of shell-and-tube construction.
SFP water circulates through the tubes while component cooling water is circulated on the shell side. The SFP cooling system design heat duty, flow rates and inlet temperatures are provided in Table 5.3.1.Holtec Report HI-2115004 5-5 Holtec Project 2119 Table 5.3.1 SFP COOLING SYTEM DESIGN PERFORMANCE DATA PARAMETER VALUE HX Heat Duty 28.64x 106 Btu/hr HX SFP Water Flow Rate 1530 gpm HX CCW Flow Rate 1800 gpm HX SFP Water Inlet Temperature 149.4 0 F HX SFP Water Outlet Temperature 111.8 0 F MX CCW Flow Inlet Temperature 90 OF HX CCW Flow Outlet Temperature 121.8 0 F Note: The heat exchanger performance presented in this table is for single train operation with a 10% reduction in SFP pump flow, a 2.2% reduction in CCW flow and 60 tubes plugged.Holtec Report HI-2115004 5-6 Holtec Project 2119 5.4 Assumptions and Design Data 5.4.1 Assumptions The following assumptions are applied to render a conservative portrayal of thermal-hydraulic conditions in the Palisades SFP.5.4.1.1 Bulk Temperature and Time-To-Boil Calculations
: 1. Heat loss by natural convection, mass diffusion and thermal radiation from the surface of the SFP water is neglected, as is conduction heat transfer through the SFP structure.
Thus, all decay heat loads are considered to be removed by the SFP cooling system alone, maximizing computed temperatures and minimizing times-to-boil.
: 2. The thermal capacity of the SFP is based on the net water volume only, completely neglecting the thermal capacity of the fuel assemblies, racks, liner and concrete SFP structure.
Since this assumption understates the SFP thermal capacity, it results in faster computed heat-up rates and shorter times-to-boil.
: 3. The decay heat load contribution of previously discharged fuel assemblies is assumed constant during all scenarios.
For the time-to-boil evaluations, the decay heat of all assemblies is assumed constant.
This assumption is conservative because it neglects the exponential decay of the heat generation from these fuel assemblies.
: 4. The postulated full core offload is assumed to have three regions. The first region, equivalent in size to a maximum size refueling batch, is assumed to have the maximum possible fuel assembly burnup from three operating cycles. The second region, equivalent in size to an average size refueling batch, is assumed to have the assembly burnup from two operating cycles. The third region, containing the balance of the assemblies in the full core, is assumed to have the burnup from one operating cycle. This conservatively maximizes the decay heat load associated with these fuel assemblies.
: 5. For the time-to-boil analyses, the failure of the SFP cooling system is assumed to occur when the maximum bulk SFP temperature for each offload scenario occurs. This minimizes the time-to-boil.
Holtec Report HI-2115004 5-7 Holtec Project 2119 5.4.1.2 Maximum Local Water and Fuel Clad Temperature Calculations
: 1. Heat loss by natural convection, mass diffusion and thermal radiation from the surface of the SFP water is neglected, as is conduction heat transfer through the SFP structure.
Thus, all decay heat loads are considered to be removed by the SFP cooling system alone, maximizing computed temperatures.
: 2. No downcomer flow is assumed to exist between the rack modules in the main SFP.3. All spent fuel storage rack cells are assumed to have the inlet flow holes geometry of the pedestal cells. This conservatively reduces the water flow area into the storage cells, thereby increasing the hydraulic resistance.
: 4. The hydraulic resistance of every rack cell in each spent fuel storage rack includes the inertial resistance that would result from a dropped fuel assembly lying across the top of the rack. This conservatively increases the total rack cell hydraulic, resistance and bounds the thermal-hydraulic effects of a fuel assembly dropped anywhere in the SFP.5. The highest heat fuel assemblies are assumed to be located together in the SFP, concentrated in the approximate center of the Region 1 racks and surrounded by the balance of the offloaded full core (the next highest heat fuel assemblies).
This conservatively maximizes the local decay heat generation rates.6. The active (i.e., heat generating) length of the fuel assemblies is assumed to be centered along the height of the spent fuel storage rack cells. The active length is actually closer to the bottom of the fuel assemblies so this geometric simplification conservatively reduces the buoyancy force that drives flow through the rack cells, which maximizes the computed water temperatures.
: 7. Instead of explicitly modeling the pipes that supply water to and remove water from the SFP (and direct it into the SFP cooling system), the inlets and outlets are modeled as 4" high slots along the length of north and south SFP walls just below the water surface. As the mixing of relatively warmer and cooler water within the SFP cooling system is dominated by buoyancy effects, this geometric simplification does not have a significant effect on the calculated results.8. An additional heat transfer resistance of 0.0005 (hrxft 2 x&deg;F)/Btu is conservatively imposed on the outside of the fuel rods, to account for any crud layer, thereby increasing the calculated fuel cladding superheat.
Holtec Report HI-2115004 5-8 Holtec Project 2119
: 9. The maximum local water temperature (at the spent fuel storage rack cell exits) and the peak heat flux (typically near the mid-height of the active fuel region) are considered to occur co-incidentally.
The superposition of these two maximum values ensures that the calculated peak fuel cladding temperature bounds the fuel cladding temperature anywhere along the length of the fuel assembly.5.4.2 Design Data 5.4.2.1 Bulk Temperature and Time-To-Boil Calculations In addition to the SFP cooling system performance data listed in Table 5.3.1, the principal design data employed to determine the maximum bulk temperatures and time-to-boil for the SFP are summarized in Table 5.4.1. This includes the design data used the compute decay heat generation rates for both previously discharged and recently offloaded fuel assemblies.
5.4.2.2 Maximum Local Water and Fuel Clad Temperature Calculations In addition to the data listed in Tables 5.3.1 and 5.4.1, the principal design data employed for the local thermal-hydraulic analyses are presented in Table 5.4.2.1-loltec Report HI-2 115004 5-9 Holtec Project 2119 Holtec Report HI-2115004 5-9 Holtec Project 2119 Table 5.4.1
 
==SUMMARY==
OF INPUTS FOR BULK TEMPERATURE ANALYSIS INPUT DATA VALUE Fuel Assembly Burnups One Cycle Burned 64 assemblies at 30 GWD/MTU Two Cycles Burned 64 assemblies at 50 GWD/MTU Three Cycles Burned 76 assemblies at 58.9 GWD/MTU Maximum Burnup Fuel Rod 62 GWD/MTU Initial 2 3 5 U Enrichment 3.5%SFP Plan Dimensions 464.83" L x 175.25" W North Tilt Pit Plan Dimensions 252" L x 60" W SFP Low Alarm Level Water Depth 35 feet North Tilt Pit Low Alarm Level Water Depth 36 feet Maximum Nominal Spent Fuel Rack Height 161 1/8" Reactor Thermal Power 2565.4 MW Reactor Core Size 204 assemblies Minimum Refueling Start Time 100 hi" (see Note 1)Fuel Transfer Rate 7.45 minutes per assembly Maximum Refueling Batch Size 76 assemblies Operating Cycle Length 18 months Number of Fuel Storage Cells Region 1 422 Region 2 474 Note 1: This time represents the starting point for analysis of all scenarios.
If necessary to ensure that all applicable temperature limits are met, longer in-core hold times prior to the start of refueling operations are determined.
Holtec Report HI-2115004 5-10 Holtec Project 2119 Table 5.4.2
 
==SUMMARY==
OF INPUTS FOR LOCAL TEMPERATURE ANALYSIS INPUT DATA VALUE SFP Nominal Plan Dimensions 465" L x 176" W (see Note 1)North Tilt Pit Plan Dimensions 252" L x 60" W (see Note 1)SFP Low Alarm Level Water Depth 35 feet North Tilt Pit Low Alarm Level Water Depth 36 feet SFP Rack-to-Wall Gaps (see Note 1)North 3.50" South 3.43" East 4.42" for Region 1 & 2.15" for Region 2 West 4.42" for Region 1 & 2.15" for Region 2 North Tilt Pit Rack-to-Wall Gaps (see Note 1)North 1.89" South 2.58" East 4.00" for Region 1 & 1.04" for Region 2 West 4.00" for Region 1 & 1.04" for Region 2)Racks-to-Floor Plenum Height 3.00" (see Note 1)Rack Baseplate
+ Cell Height 156.13" Active Fuel Length 122" Fuel Assembly Array Size 15x15 Rack Cell Pitch 10.25" for Region 1 & 9.17" for Region 2 Minimum Rack Cell Nominal ID 8.75" for Region 1 & 9.00" for Region 2 Number of Cell Inlet Flow Holes per Rack 4 Pedestal Location Rack Pedestal Location Cell Inlet Flow Holes 3/4" radius semi-circle for Region 1 Size and Shape 2" diameter circle for Region 2 Assembly Axial Peaking Factor 1.4 Note 1: The model is constructed by using nominal plan dimensions, which are then reduced by 50% of the minimum rack-to-wall gap at each wall to ensure a bounding solution.
The as-modeled bottom plenum height is also conservatively lower than the actual dimensions.
Holtec Report HI-2 115004 5-11 Holtec Project 2119 Holtec Report HI-2115004 5-11 Holtec Project 2119 5.5 Heat Loads and Bulk Pool Temperatures 5.5.1 Decay Heat Load Calculations Analyses are performed to calculate the accumulated decay heat of all previously discharged fuel assemblies (i.e., assemblies with at least one cycle of decay time) stored in the SFP and the heat (as a function of time) for all recently offloaded fuel assemblies.
The decay heats are calculated using Oak Ridge National Laboratory's ORIGEN2 program [5.5.1 ].The cumulative decay heat from previous discharges (Peons) irradiated to a bounding exposure is computed as approximately 4.4 million Btu/hr for a refueling batch offload (Scenario
: 1) and approximately 4.0 million Btu/hr for a full core offload. The value for the full core offload is slightly smaller because it has less previously discharged fuel assemblies to make room for more recently discharged fuel assemblies.
This decay heat load is included in the bulk pool temperature calculations as a constant background heat input as described next in the next subsection.
The decay heat from recently offloaded fuel assemblies is computed as presented in Figure 5.5.1.This decay heat load is included in the bulk pool temperature calculations as a time-varying heat input as described next in the next subsection.
5.5.2 Maximum Bulk SFP Temperature Calculation This analysis is performed to determine the transient SFP bulk temperature for the postulated fuel assembly offload scenarios.
The mathematical formulation for this analysis can be explained with reference to the simplified heat exchanger alignment shown in Figure 5.5.2. The governing differential equation for bulk temperature can be written by utilizing conservation of energy as: dT CX- Pcons + Q(r) -QHX (T) -QEV(T, TA)dr E Holtec Report HI-2 115004 5-12 Holtec Project 2119 Holtec Report HI-2115004 5-12 Holtec Project 2119 where: C is the thermal capacity of water in the SFP, Btu/&deg;F Pcons is the heat generation rate from previously discharged fuel, Btu/hr Q(T) is the heat generation rate from recently offloaded fuel vs. time, Btu/hr QHX(T) is the SFP cooling system heat rejection, Btu/hr QEv(T,TA) is the evaporative and passive sensible heat loss, Btu/hr T is the bulk temperature, OF TA is the building ambient temperature, &deg;F The SFP cooling system heat rejection, QHx(T) is defined by the following governing equation.QHx (T) = Wc x cp x p x (T -Tc)where: Wc is the cooling water flow rate, lb/hr Cp is the cooling water specific heat, Btu/(lb-&deg;F) p is the temperature performance parameter for the heat exchanger T is the SFP water bulk temperature, &deg;F Tc is the cooling water inlet temperature, OF The equation used to determine the temperature performance parameter, p of the SFP cooling system heat exchanger is: P TCo T c Tpi- TC where: Tc is the cooling water inlet temperature, OF Tco is the cooling water outlet temperature, OF Tpi is the SFP water inlet temperature, OF The SFP decay heat contribution from all previously discharged fuel assemblies is held constant during the entire analysis because its decrease with decay time after shutdown can be conservatively neglected.
The decay heat generation, Q(T), of the recently offloaded fuel will decay exponentially with elapsed time after reactor shutdown.
The decay heat generation Q(r) is a function of the elapsed time after reactor shutdown, number of fuel assemblies'discharged, and in-core exposure.Holtec Report HI-2115004 5-13 I Holtec Project 2119 The evaporative and passive sensible heat losses, QEV(T,TA), are a nonlinear function of the SFP water temperature (T) and the building ambient temperature (TA), and include cooling by evaporation and natural convection heat transfer from the pool surface. For conservatism, these cooling mechanisms are completely neglected.
The results of the maximum bulk temperature analyses for the fuel offload scenarios are summarized in Table 5.5.1. The results demonstrate that bulk pool water temperatures remain below the prescribed limits during fuel discharges.
These results comply with the acceptance criteria set forth in Section 5.2. It is noted that an in-core hold time in excess of the minimum value is necessary for the full core offload. This requirement will be implemented as an administrative control and integrated with the plant's operating procedures.
The SFP bulk temperature and decay heat in the SFP, both as functions of time after reactor shutdown, are shown in Figures 5.5.3 and 5.5.4 for the refueling batch offload and the full core offload, respectively.
The maximum decay heat is reached upon completion of fuel transfer.
The thermal inertia of the SFP water delays the bulk temperature maximum, the lag being a direct result of the system thermal capacitance.
The coincident time to the maximum temperature is the summation of refueling start time, fuel transfer time and the lag time.5.5.3 Minimum Time-To-Boil Calculation This analysis is to determine the time that it takes for the SFP water to boil if all forced cooling becomes unavailable.
Clearly, the most critical instant of loss-of-cooling is when the water temperature has reached its maximum value. Although the probability of a loss-of-cooling event occurring when the water is exactly at its hottest is low, the calculations are performed based on the hottest possible initial temperature.
The following differential equation governs the thermal response of the water in the SFP without heat rejection.
dT C(r) x -- = Pcons + Q(r)dr Holtec Report HI-2115004 5-14 Holtec Project 2119 where: C(T) is the time-varying thermal capacity of the SFP, Btu/&deg;F Pcons is the heat generation rate from previously discharged fuel, Btu/hr Q(T) is the heat generation rate from recently offloaded fuel vs. time, Btu/hr T is the bulk temperature, &deg;F The time-to-boil calculations are conservatively performed assuming no makeup water is available.
The time-to-boil results are summarized in Table 5.5.2. The results show that nearly two hours is required for the SFP water to start boiling. For a scenario of loss of all forced cooling, sufficient time would be available for necessary repairs or to implement alternate cooling or makeup water.Holtec Report HI-2115004 5-15 Holtec Project 2119 Table 5.5.1
 
==SUMMARY==
OF BULK TEMPERATURE RESULTS FUEL PEAK BULK TIME AFTER COINCIDENT MINIMUM IN-OFFLOAD TEMPERATURE REACTOR DECAY HEAT CORE HOLD SCENARIO (OF) SHUTDOWN (BTU/HR) TIME (HR)(HR)1 -Refueling 124 116 16.41 x 106 100 Batch 2 -Full Core 150 188 28.90x 106 158 Holtec Report HI-2115004 5-16 Holtec Project 2119 Table 5.5.2
 
==SUMMARY==
OF TIME-TO-BOIL RESULTS OFFLOAD SCENARIO MINIMUM TIME-TO-BOIL (HR)1 -Refueling Batch 4.6 2 -Full Core 1.8 Holtec Report HI-2115004 5-17 Holtec Project 2119
-Partial Core Offload -Full Core Offload 35 30 Full Core Offload 25 m C 0 20 ig 0 ,J i 15 w Partial Core Offload 10 5 0 100 200 300 400 500 600 Time after Reactor Shutdown (hr)FIGURE 5.5. 1: RECENTLY OFFLOADED FUEL DECAY HEAT VERSUS TIME 700 Holtec Report 111-2115004 5-18 Holtec Project 2119 Holtec Report HI-2115004 5-18 Holtec Project 2119 EVAPORATION LOSS QEv(T,TA) (conservatively neglected)
FIGURE 5.5.2: SIMPLIFIED HEAT EXCHANGER ALIGNMENT Holtec Report 111-2115004 5-19 Holtec Project 2119 Holtec Report HI-2115004 5-19 Holtec Project 2119 I- Bulk Temperature
-Decay HeatI 130 1.80E+07 125 1.60E+07 120 1.40E+07 115 1.20E+07* &deg;u 00 E* 0 110 1.OOE+07 Z--u 105 8.OOE+06 100 6.OOE+06 95 4.00E+06 0 100 200 300 400 500 600 700 Time After Reactor Shutdown (hr)FIGURE 5.5.3: BULK TEMPERATURE AND DECAY HEAT LOAD VERSUS TIME -REFUELING BATCH OFFLOAD SCENARIO I Holtec Report HI-2 115004 5-20 Holtec Project 2119 Holtec Report HI-2115004 5-20 Holtec Project 2119 I -Bulk Temperature
-Decay Heat 155 145 135 a 125 E S 115 105 95 3.20E+07 2.70E+07 2.20E+07 0 1.70E+07 -l 1.20E+07 7.00E+06 2.OOE+06 0 100 200 300 400 500 600 700 Time After Reactor Shutdown (hr)FIGURE 5.5.4: BULK TEMPERATURE AND DECAY HEAT LOAD VERSUS TIME -FULL CORE OFFLOAD SCENARIO 2 Holtec Report HI-2 115004 5-21 Holtec Project 2119 Holtec Report HI-2115004 5-21 Holtec Project 2119 5.6 Local Water and Fuel Claddine Temneratures The objective of the local temperature analyses is to demonstrate that the principal thermal-hydraulic criterion of ensuring local subcooled conditions in the SFP is met for all scenarios:
Adequate cooling of recently offloaded fuel is demonstrated by performing a rigorous evaluation of the coupled velocity and temperature fields in the SFP created by the interaction of buoyancy driven flows and water injection/egress.
For determining the maximum local water temperature, a 3-dimensional Computational Fluid Dynamics (CFD) analysis is implemented.
There are several significant geometric and thermal-hydraulic features of the SFP that need to be considered for a rigorous CFD analysis.
From a fluid flow-modeling standpoint, there are two regions to be considered.
One region is the bulk region outside the spent fuel storage racks, where the classical Navier-Stokes equations are solved with turbulence effects included.
The other region is the heat-generating zone of spent fuel storage racks loaded with fuel assemblies, where water flow is directed vertically upwards by the buoyancy forces through relatively small flow channels formed by the fuel assembly rod arrays in each rack cell. The racks are modeled as porous medium regions in which Darcy's Law[5.6.1 ] governs fluid flow.The distributed heat sources in the spent fuel storage racks are modeled by identifying distinct heat generation zones considering full-core discharge, peaking effects, and presence of background decay heat from previous discharges.
Three heat generating zones were modeled.The first consists of background heat from previously discharged fuel assemblies, while the remaining two zones are for fuel assemblies recently offloaded from the reactor. This is a conservative model, since all recently offloaded fuel assemblies with higher than average decay heats are postulated to be placed in a contiguous area.The CFD analysis is performed using the FLUENT [5.6.2] fluid flow and heat transfer modeling program. The FLUENT code enables buoyancy flow and turbulence effects to be included in the CFD analysis.
Turbulence effects are modeled by relating time-varying "Reynolds' Stresses" to the mean bulk flow quantities by the standard k-F. turbulence model.Holtec Report HI-2115004 5-22 Holtec Project 2119 The peak fuel rod cladding temperature is computed by following a series of calculation steps as outlined below: Step 1: Compute the maximum local water temperature as just described above.Step 2: Compute .the maximum cladding to local water temperature difference (ATc).Step 3: Compute a bounding maximum fuel rod cladding temperature by adding ATe to the maximum local water temperature.
The procedure to perform Step 2 is presented next.The maximum specific decay power of a single fuel assembly among the recently offloaded fuel assemblies is denoted by QA. A fuel rod can produce f, times the average heat emission rate over a small length, where f, is the axial peaking factor. The axial heat distribution in a fuel rod is highest in the central region, and tapers off at its two extremities.
Thus, peak cladding heat flux per unit heat transfer area of fuel assembly is given by the equation: qpeak QAXz A rods where Arods is the total external heat transfer area of the cladding in the active fuel region of a single fuel assembly (ft 2).Within each fuel assembly sub-channel, water is continuously heated by the cladding as it moves axially upwards from bottom to top under laminar flow conditions.
Rohsenow and Hartnett[5.6.3] report a Nusselt number, Nu, for heat transfer in a laminar flow situation through a heated channel as: Holtec Report HI-2115004 5-23 Holtec Project 2119 Nu= xDh = 4.364 k,,ater h, = 4.364 x kwater Dh where: kwater is the water thermal conductivity, Btu!(hr-ft-&deg;F) 1k is the laminar flow convective heat transfer coefficient, Btu/(hr-ft 2-&deg;F)Dh is the sub-channel hydraulic diameter, ft In order to introduce some additional conservatism in the analysis, it is assumed that the fuel cladding has a crud deposit thermal resistance, Rud, which covers the entire surface. Therefore, the overall heat transfer coefficient U, considering a crud deposit resistance Prcd, can be defined by the following:
S1 U-Ch, The temperature drop, ATe, between the outer surface of the fuel cladding and the water flowing up through the assembly at the peak cladding flux location is computed by the following:
AT, = qpeak U Finally, the maximum fuel rod temperature is defined by the following:
Tod , oc. 1 AT, where: Trod is the maximum fuel clad temperature Tlocal is the maximum local water temperature Iloltec Report HI-2 115004 5-24 Holtec Project 2119 Holtec Report HI-2115004 5-24 Holtec Project 2119 The bounding full core offload scenario is considered.
A solution of the CFD model is performed to obtain the coupled flow and temperature fields, the maximum local water temperature is extracted from the temperature field, and then the maximum fuel cladding temperature is computed as described.
The maximum local water temperature, fuel cladding superheat and bounding fuel cladding temperature are summarized in Table 5.6.1. At the top of the active fuel, the local saturation temperature is approximately 240'F. From the local water and fuel cladding temperature results, it is concluded that local water and fuel cladding temperatures remain below saturation.
Temperature contours in a vertical plane through the center of the main SFP are shown in Figure 5.6.1. This figure shows that local hot spots induced by water circulation in the racks are rapidly dissipated in the bulk water resulting in a nearly uniform temperature distribution away from the racks. Temperature contours in a vertical plane through the center of the North Tilt Pit are shown in Figure 5.6.2. These two figures confirm that fuel assemblies are safely and reliably cooled by natural convection action. Local hot spots induced by water circulation in the racks are rapidly dissipated in the pool water resulting in a nearly uniform temperature distribution away from the racks.Holtec Report HI-2115004 5-25 Holtec Project 2119 Table 5.6.1
 
==SUMMARY==
OF LOCAL TEMPERATURE RESULTS PARAMETER CALCULATED VALUE (&deg;F)Maximum Water Temperature 168 Fuel Cladding Superheat 24 Bounding Fuel Cladding Temperature 192 Holtec Report 111-2115004 5-26 Holtec Project 2119 Holtec Report HI-2115004 5-26 Holtec Project 2119 I 1.68e+02 1.65e+02 1 .62e+02 1.59e+02 1.57e+02 1 .54e+02 1.51e+02 1.48e+02 1.46e+02 1.43e+02 1 .40e+02 1.37e+02 1.35e+02 1.32e+02 1.29e+02 1.26e+02 1.24e+02 1.21e+02 1.18e+02 1.15e+02 1.13e+02 I Contours of Static Temperature (f)Nov 25, 2011 FLUENT 6.3 (3d, dp, pbns, ske)FIGURE 5.6. 1: CONTOURS OF STATIC TEMPERATURE IN A VERTICAL PLANE THROUGH THE CENTER OF THE MAIN SFP Holtec Keport 111-211 MJIJ4 5-27 Holtec Project 2119 oltec Report 1-2115004 5-27 Holtec Project 2119 I 1.53e+02 1.53e+02 1.52e+02 1.52e+02 1.52e+02 1.51 e+02 1.51e+02 1.51e+02 1.51e+02 1.50e+02 1.50e+02 1.50e+02 1.50e+02 1.49e+02 1.49e+02 1.49e+02 1.48e+02 1.48e+02 1.48e+02 1.48e+02 1.47e+02 I II I I Contours of Static Temperature (f)Nov 25, 2011 FLUENT 6.3 (3d, dp, pbns, ske)FIGURE 5.6.2: CONTOURS OF STATIC TEMPERATURE IN A VERTICAL PLANE THROUGH THE CENTER OF THE NORTH TILT PIT Holtec Report HI-2 115004 5-28 Holtec Project 2119 Holtec Report HI-2115004 5-28 Holtec Project 2119
 
===5.7 References===
[5.2.1 ] "OT Position Paper for Review and Acceptance of Spent Fuel Storage and Handling Applications," April 14, 1978.[5.5.1] A. G. Croff, "ORIGEN 2 -A Revised and Updated Version of the Oak Ridge Isotope Generation and Depletion Code," ORNL-5621, Oak Ridge National Laboratory, 1980.[5.6.1 ] "Flow of Fluids Through Valves, Fittings, and Pipe," Crane Technical Paper No. 410, Crane Valve Company, Twenty-Second Printing, 1985.[5.6.2] FLUENT Computational Fluid Dynamics Software, Fluent Inc., Centerra Resource Park, 10 Cavendish Court, Lebanon, NH 03766.[5.6.3] Rohsenow, W.M. and J.P. Hartnett, "Handbook of Heat Transfer," McGraw Hill Book Company, NY, 1973.Holtec Report HI-2115004 5-29 Holtec Project 2119 CHAPTER 6: STRUCTURAL/SEISMIC CONSIDERATIONS
 
===6.1 Introduction===
The structural safety analysis of the spent fuel racks, proposed to be installed in the Palisades fuel pool, is summarized in this chapter. The new Palisades racks, as described in Chapter 2 herein, are free standing and autonomously supported structures.
As is typical of state-of-the-art rack designs, each module contains an array of free standing fuel assemblies whose response during an earthquake event is apt to be highly non-linear
[6.1.1]. Because of the significant physical non-linearities inherent to the fuel rack dynamics, the three dimensional time history integration method of analysis whose antecedents go back to the past three decades[6.1.2;6.1.3;6.1.4]
has been used in the qualification of Palisades racks. Furthermore, in order to establish a sound basis for the safety analysis, it is necessary to use proven computer codes and proven methodologies in the analysis:
The computer code and the solution methodology employed in this safety analysis fulfill the proven-ness and benchmarking criteria in ISG-21[6.1.5]. The objective of the seismic analysis of the fuel racks is to ensure the following:
: 1. The stored fuel assemblies will not sustain failure from repeated rattling inside their storage cells.2. The stresses in the rack structure will meet the applicable code stress limits.3. Buckling of the rack modules in the cellular region is not indicated.
: 4. There is no risk of impact between the rack modules in the active fuel region.5. Failure from cyclic fatigue due to the vibratory seismic loads is not indicated.
: 6. The bearing pads that support the rack pedestals are sufficiently stiff to maintain the bearing stresses on the concrete floor within ACI limits.The information presented in this chapter provides the technical evidence that all of the above safety objectives are satisfied.
Holtec Report HI-2115004 6-1 Holtec Project 2119 In addition to the seismic analysis, the fuel rack modules are also evaluated for their adequacy under long-term normal storage conditions during which the dead weight and stresses from differential thermal expansion are the only applicable loadings.The capacity of the reinforced concrete structure to maintain the water inventory in the pool under all operating conditions is evaluated in Chapter 8. The integrity of the pool liner is also considered in Chapter 8.Holtec Report HI-21 15004 6-2 Holtec Project 2119 I Holtec Report HI-2115004 6-2 Holtee Project 2119 1 6.2 Acceptance Criteria Applicable to the Fuel Racks and their Contents 6.2.1 Fuel Acceptance Criteria: The acceptable g-loads for spent nuclear fuel are provided in reference
[6.2.1]. However, for conservatism, a lower bound value of 60g's for both lateral and axial impact is used herein from docket number 71-9261 [6.2.2].6.2.2 Rack Acceptance Criteria: To confirm the structural integrity of the racks, it is necessary to demonstrate compliance with the USNRC Standard Review Plan (SRP) Section 3.8.4 [6.2.3]. The rack structures are designed to meet the requirements of the ASME Code, Section III, Subsection NF [6.2.5] for Class 3 linear-type supports.
The relevant design criteria are summarized below.There are two principal design criteria, which must be satisfied by the rack modules: a. Kinematic Criteria According to Section 3.8.5 of Ref [6.2.3], the minimum required safety margin against overturning under a Safe Shutdown Earthquake (SSE) event and the OBE events are 1.1 and 1.5, respectively.
The margin of safety is defined here as the ratio of the rotation required to produce incipient tipping in either principal plane to the actual maximum rotation in that plane from the time history solution.
The kinematic acceptance criterion is. made more stringent in this evaluation by stipulating that the safety margin of 1.5 be satisfied under both the OBE and the SSE event. (The SSE event controls.)
: b. Code Stress Limits under Different Service Conditions The stress limits under the postulated load combinations must be within the limits defined in ASME Code, Section III, Subsection NF [6.2.5]. The applicable loads and their combinations, considered in this seismic analysis of rack modules, are excerpted from Section 3.8.4 of Ref Holtec Report HI-2115004 6-3 Holtec Project 2119 1
[6.2.3]. The applicable load combinations are identified below along with their acceptance limits in the following table.Load Combination Acceptance Limit D+L D + L + T, Level A service limits D + L + To + E (note 1)D + L + Ta + E (note 1)Level B service limits D + L + T, D + L + Ta + E' (note 1) Level D service limits D + L + Fd The functional capability of the racks should be demonstrated Notes: 1) In addition to the acceptance limit given in the table above, the stresses induced in the rack modules due to this load combination must also be below the lesser of 2xSy or Su per Ref. [6.2.1 ] (where Sy is yield stress and Su is ultimate tensile stress).Abbreviations are those used in Ref [6.2.3]: D = Dead weight induced loads (including fuel assembly weight)L = Live load (not applicable for the fuel rack, since there are no moving objects in the rack load path). Note that it is accepted practice to consider the fuel weight as a dead weight.E = Operating Basis Earthquake (OBE)E5 = Safe Shutdown Earthquake (SSE)To = Differential temperature induced loads, based on the most critical transient or steady state condition under normal operation or shutdown conditions.
Ta = Differential temperature induced loads, based on the postulated abnormal design conditions.
Holtec Report HI-2115004 6-4 Holtec Project 2119 1 Fd Force caused by the accidental drop of the heaviest load from maximum possible height. This load is considered to be an accident condition.
The evaluation of this load condition is discussed in Chapter 7.Because of water submergence and free standing disposition, the fuel racks experience minimal stresses from differential thermal expansion.
Nevertheless, a hypothetical scenario is postulated herein that can produce local thermal stresses in the rack's cellular structure.
Because local thermal stresses lie outside the purview of Class 3 "NF' structures, the T, and Ta loads listed above need not be considered.
In this safety analysis, however, they are treated as viable loads under which the Code stress limit for secondary stresses must be satisfied.
The worst thermal stress field in a fuel rack is obtained when an isolated storage location has a fuel assembly generating heat at maximum postulated rate and surrounding storage locations contain no fuel. Heated water makes unobstructed contact with the inside of the storage walls, thereby producing maximum possible temperature difference between adjacent cells. Secondary stresses produced are limited to the body of the rack; that is, support pedestals do not experience secondary (thermal) stresses.6.2.3 Stress Limits for the "NF" Structure 6.2.3.1 Limits from the ASME Code The stress limits presented below apply to the rack structure and are derived from the ASME Code, Section III, Subsection NF [6.2.5]. Parameters and terminology used is in accordance with the ASME Code. Upset loads (Level B) are conservatively evaluated against ASME Level A stress limits. Material properties are obtained from the ASME Code Section II, Part D [6.16], and are listed in Table 6.5.1.6.2.3.1.1 Normal and Upset Conditions (Level A or Level B)a. Allowable stress in tension on a net section is: Holtec Report HI-2115004 6-5 Holtec Project 2119 1 Ft = 0.6 Sy where, Sy = yield stress at temperature, and Ft is equivalent to primary membrane stress.b. Allowable stress in shear on a net section is: F, = 0.4 Sy c. Allowable stress in compression on a net section is: F.= Sy{47 -4k e where kI/r for the main rack body is based on the full height and cross section of the honeycomb region and does not exceed 120 for all sections.1 = unsupported length of component k = length coefficient which gives influence of boundary conditions.
The following values are appropriate for the described end conditions:
1 (simple support both ends)2 (cantilever beam)V2 (clamped at both ends)r = radius of gyration of component d. Maximum allowable bending stress at the outermost fiber of a net section, due to flexure about one plane of symmetry is: Fb = 0.60 Sy (equivalent to primary bending)e. Combined bending and compression on a net section satisfies:
f, + Cr fb 1+ Cmy fby<F. D. Fb. D, Fby where: fa = Direct compressive stress in the section fbx = Maximum bending stress along x-axis fby = Maximum bending stress along y-axis Holtec Report HI-2115004 6-6 Holtec Project 2119 1 Cmx = 0.85 Cmy = 0.85 Dx = 1 -(fa/F'ex)D = 1- (fa/F'ey)F'ex,ey = (72r E)/(2.15 (kl/r)2,y)
E -Young's Modulus and subscripts x,y reflect the particular bending plane.f. Combined flexure and compression (or tension) on a net section: fa + G, + fy < 1.0 0.6 S, Fb. Fb, The above requirements are to be met for both direct tension and compression.
: g. Welds Allowable maximum shear stress on the net section of a weld is given by: Fw = 0.3 Su where Su is the weld material ultimate strength at temperature.
For fillet weld legs in contact with base metal, the shear stress on the gross section is limited to 0.4Sy, where Sy is the base material yield strength at temperature.
6.2.3.1.2 Level D Service Limits Section F-1334 (ASME Section III, Appendix F) [6.2.6], states that the limits for the Level D condition are the minimum of 2 or 1.167 Su/Sy times the corresponding limits for the Level A condition if Su > 1.2Sy, or 1.4 if Su -< 1.2Sy except for requirements specifically listed below. Su and Sy are the ultimate strength and yield strength at the specified rack design temperature.
Examination of material properties for 304 and 304L stainless demonstrates that the S, > 1.2Sy condition stated above is met.Holtec Report HI-2115004 6-7 Holtec Project 2119 1 Exceptions to the above general multiplier are the following:
a) Stresses in shear shall not exceed the lesser of 0.72Sy or 0.42S,. In the case of the austenitic Stainless material used here, 0.72Sy governs.b) Axial Compression Loads shall be limited to 2/3 of the calculated buckling load.c) Combined Axial Compression and Bending -The equations for Level A conditions shall apply except that: Fa = 0.667 x Buckling Load/ Gross Section Area, and the terms F',x and F'ey may be increased by the factor 1.65.d) For welds, the Level D allowable maximum weld stress is not specified in Appendix F of the ASME Code. An appropriate limit for weld throat stress is conservatively set here as: Fw = (0.3 Su) x factor where: factor = (Level D shear stress limit)/(Level A shear stress limit)=0.72 x Sy/0.4 x Sy= 1.8 6.2.3.2 Dimensionless Stress Factors The term "stress factor" used herein implies the ratio of the computed stress to its corresponding allowable.
The maximum allowable value of each stress factor is 1.0.The following types of Stress Factors are defined for used fuel racks: R 1  = Ratio of direct tensile or compressive stress on a net section to its allowable value (note pedestals only resist compression)
Holtec Report HI-2115004 6-8 Holtec Project 2119 R2 Ratio of gross shear on a net section in the x-direction to its allowable value R3 Ratio of maximum x-axis bending stress to its allowable value for the section R4 Ratio of maximum y-axis bending stress to its allowable value for the section R5= Combined flexure and compressive factor (as defined in the foregoing)
R6 = Combined flexure and tension (or compression) factor (as defined in the foregoing)
R7 Ratio of gross shear on a net section in the y-direction to its allowable value.6.2.4 Safety Margin against Fatigue Failure The cumulative damage factor, U, as defined in Section 6.7, must be shown to be less than or equal to 1.0.Holtec Report HI-2115004 6-9 Holtec Project 2119 1 6.3 Acceptance Criteria for the Bearine Pads 6.3.1 Bearing Pad Acceptance Criteria The bearing pad must be adequately sized such that it is capable of safely diffusing the maximum vertical load from the rack pedestals into the concrete floor during a seismic event. To satisfy this criterion, the resulting bearing stress in the concrete under the maximum pedestal load (including applicable ACI load factors) must be less than the limit specified in Section 10.14 of the ACI Code [6.9. 1]which implies that the bearing stress must be less than:=2xWx0.85xf, where:= strength reduction factor = 0.7=minimum compressive strength of concrete = 3,000 psi A factor of 2 is included in the equation for ab since the concrete floor slab is wider than the bearing pad on all sides. Inserting the required data in the above formula, for Palisades, the bearing stress limit is ab = 3,570 psi Holtec Report HI-2 115004 6-10 Holtec Project 2119 I Holtec Report HI-2115004 6-10 Holtec Project 2119 '1 6.4 Dynamic Analysis Methodology In this section, the DYNARACK methodology used to analyze racks is discussed
.Holtec International has been utilizing this methodology since the late 1980's to perform dynamic analysis of underwater fuel rack arrays for scores of nuclear plants (Table 6.4.1 is a partial list of recent use).It is recognized that the response of a freestanding rack module to seismic inputs is highly nonlinear and involves a complex combination of motions (sliding, rocking, twisting, and turning), resulting in impacts and friction effects. Some of the unique attributes of the rack dynamic behavior include a large fraction of the total structural mass in a confined rattling motion, friction support of rack pedestals against lateral motion, and large fluid coupling effects due to deep submergence and independent motion of closely spaced adjacent structures.
Linear methods, such as modal analysis and response spectrum techniques, cannot accurately simulate the structural response of such a highly nonlinear structure to seismic excitation.
An accurate simulation is obtained only by direct integration of the nonlinear equations of motion with the three pool slab acceleration time-histories applied as the forcing functions acting simultaneously.
The classical method of simulating the dynamic behavior of an array of rack modules is known as "Whole Pool Multi-Rack" (WPMR) analysis, which is explained in the following subsections.
6.4.1 Key Parameters in the Dynamic Analysis Reliable assessment of the stress field and kinematic behavior of the rack modules calls for a conservative dynamic model incorporating all key attributes of the actual structure.
This means that the model must feature the ability to execute the concurrent motion forms compatible with the freestanding installation of the modules.The model must possess the capability to affect momentum transfers which occur due to rattling of fuel assemblies inside storage cells and the capability to simulate lift-off and subsequent Holtec Report HI-2115004 6-11 Holtec Project 2119 impact of support pedestals with the underlying bearing pads. Some of the key attributes of the dynamic model are as follows: Simulating Interface Friction The coefficient of friction (gi) between the pedestal supports and the pool floor is indeterminate.
According to Rabinowicz
[6.4.1], results of 199 tests performed on austenitic stainless steel plates submerged in water show a mean value of gi to be 0.503 with standard deviation of 0.125.Upper and lower bounds (based on two standard deviations) are 0.753 and 0.253, respectively.
Analyses are accordingly performed for a Gaussian (normal) distribution of coefficient of friction values with a mean of 0.5 and lower and upper limits of 0.2 and 0.8, respectively.
Rack Beam Behavior:
Rack elasticity, relative to the rack base, is included in the model by introducing linear springs to represent the elastic bending action, twisting, and extensions.
Impact Phenomena:
Compression-only gap elements are used to provide for opening and closing of interfaces such as the pedestal-to-bearing pad interface, and the fuel assembly-to-cell wall interface.
These interface gaps are modeled using nonlinear spring elements.
The term "nonlinear spring" is a generic term used to denote the mathematical representation of the condition where a restoring force is not linearly proportional to displacement.
Fluid Coupling:
Holtec International extended Fritz's classical two-body fluid coupling model to multiple bodies and utilized it to perform the first two-dimensional multi-rack analysis (Diablo Canyon, ca. 1987). Subsequently, laboratory experiments were conducted to validate the multi-rack fluid coupling theory [6.4.3]. This technology was incorporated in the Holtec-proprietary computer program DYNARACK [6.4.2], which handles simultaneous simulation of all racks in the pool as a Whole Pool Multi-Rack 3-D analysis, and it has been in use for over two decades.Holtec Report HI-2115004 6-12 Holtec Project 2119 1 6.4.2 Essentials of the Dynamic Model For closely spaced racks, demonstration of kinematic compliance is verified by including all modules in one comprehensive simulation using a WPMR model. In WPMR analysis, all rack modules are modeled simultaneously and the coupling effect due to this multi-body motion is included in the analysis.The dynamic modeling of the rack structure must be prepared with special consideration of all nonlinearities and parametric variations.
Particulars of modeling details and assumptions for the WPMR analysis of racks are given in the following:
: a. The fuel rack structure motion is captured by modeling the rack as a 12 degree-of-freedom structure.
Movement of the rack cross-section at any height is described by six degrees-of-freedom of the rack base and six degrees-of-freedom at the rack top. In this manner, the response of the module, relative to the baseplate, is captured in the dynamic analyses once suitable springs are introduced to couple the rack degrees-of-freedom and simulate rack stiffness.
: b. Rattling fuel assemblies within the rack are modeled by five lumped masses located at H, 0.75H, 0.5H, 0.25H, and at the rack base (H is the rack height measured above the baseplate).
Each lumped fuel mass has two horizontal degrees-of-freedom.
Vertical motion of the fuel assembly mass is assumed equal to rack vertical motion at the baseplate level. The centroid of each fuel assembly mass can be located off-center, relative to the rack structure centroid at that level, to simulate a partially loaded rack.c. Fluid coupling between the rack and fuel assemblies, and between the rack and wall, is simulated by appropriate inertial coupling in the system kinetic energy.Inclusion of these effects uses the methods of [6.4.5] for rack-to-fuel coupling and for rack-to-rack coupling.Holtec Report HI-2115004 6-13 Holtec Project 2119 1
: e. Fluid damping and form drag are conservatively neglected.
: g. Potential impacts between the cell walls of the racks and the contained fuel assemblies are accounted for by appropriate compression-only gap elements between masses involved.
The possible incidence of rack-to-wall or rack-to-rack impact is simulated by gap elements at the top and bottom of the rack in two horizontal directions.
Bottom gap elements are located at the baseplate elevation.
The initial gaps reflect the presence of baseplate extensions, and the rack stiffnesses are chosen to simulate local structural detail.h. The model for each rack is considered supported, at the base level, on four or five pedestals consistent with its design. Pedestals are modeled by non-linear compression gap elements in the vertical direction and as "rigid links" for transferring horizontal stress. Each pedestal support is linked to the bearing pad by two piecewise linear friction spring elements.
These elements are properly located with respect to the centerline of the rack beam, and allow for arbitrary rocking and sliding motions. The spring rate for the friction springs includes any lateral elasticity of the stub pedestals.
Local pedestal vertical spring stiffness accounts for floor elasticity and for local rack elasticity just above the pedestal.i. Movement of fuel assemblies inside the storage locations causes the gap between fuel assemblies and cell wall to change from a maximum of twice the nominal gap to a theoretical zero gap. Fluid coupling coefficients are based on the nominal gap in order to provide a conservative measure of fluid resistance to gap closure.Figure 6.4.1 shows a schematic of the dynamic model of a single rack. The schematic depicts many of the characteristics of the model including all of the degrees-of-freedom and most of the spring restraint elements.Table 6.4.2 provides a complete listing of each of the 22 degrees-of-freedom for a rack model.Six translational and six rotational degrees-of-freedom (three of each type at top and bottom of Holtec Report HI-2115004 6-14 Holtec Project 2119 i rack) describe the motion of the rack structure.
Rattling fuel mass motions (shown at nodes 1*, 2, 3*, 4* and 5* in Figure 6.4.1) are described by ten horizontal translational degrees-of-freedom (two at each of the five fuel masses). The vertical fuel mass motion is assumed (and modeled) to be the same as that of the rack baseplate.
Figure 6.4.2 depicts the fuel to rack impact springs (used to develop potential impact loads between the fuel assembly mass and rack cell inner walls) in a schematic isometric.
Only one of the five fuel masses is shown in this figure. Four compression-only springs, acting in the horizontal.
direction, are provided at each fuel mass.Figure 6.4.3 provides a 2-D schematic elevation of the storage rack model. This view shows the vertical location of the five storage masses and some of the support pedestal spring members.Figure 6.4.4 shows the modeling technique and degrees-of-freedom associated with rack elasticity.
In each bending plane shear and bending springs simulate elastic effects [6.4.6].Linear elastic springs coupling rack vertical and torsional degrees-of-freedom are also included in the model.Figure 6.4.5 depicts the inter-rack impact springs (used to develop potential impact loads between racks or between rack and wall).Three element types are used in the rack models. Type 1 elements represent the linear elastic beam-like behavior of the integrated rack cell matrix. Type 2 elements are the piecewise linear friction springs used to develop the appropriate horizontal forces between the rack pedestals and the supporting bearing pads. Type 3 elements are non-linear gap elements, which model gap closures and subsequent impact loadings (i.e., between fuel assemblies and the storage cell inner walls, rack outer periphery spaces and the vertical forces between the rack pedestals and the supporting bearing pads).Holtec Report HI-2115004 6-15 Holtec Project 2119 1 If the simulation model is restricted to two dimensions (one horizontal motion plus one vertical motion, for example), for the purposes of model clarification only, then Figure 6.4.3 describes the configuration.
This simpler model is used to elaborate on the various stiffness modeling elements.Type 3 gap elements modeling impacts between fuel assemblies and racks have local stiffness Ki in Figure 6.4.3. Support pedestal spring rates Ks are modeled by type 3 gap elements.
Local compliance of the concrete floor is included in Ks. The type 2 friction elements are shown in Figure 6.4.3 as Kf. The spring elements depicted in Figure 6.4.4 represent type 1 elements.Friction at the support/bearing pad interface is modeled by the piecewise linear friction springs with suitably large stiffness Kf up to the limiting lateral load jN, where N is the current compression load at the interface between support and bearing pad. At every time-step during transient analysis, the current value of N (either zero if the pedestal has lifted off the bearing pad, or a compressive finite value) is computed.The gap element Ks, modeling the effective compression stiffness of the structure in the vicinity of the support, includes stiffness of the pedestal, local stiffness of the underlying pool slab, and local stiffness of the rack cellular structure above the pedestal.The previous discussion is limited to a 2-D model solely for simplicity.
Actual analyses incorporate 3-D motions.During the seismic event, all racks in the pool are subject to the input excitation in three orthogonal directions simultaneously.
The motion of each freestanding module would be autonomous and independent of others as long as they did not impact each other and no water were present in the pool. While the scenario of inter-rack impact depends on rack spacing, the effect of water (the so-called fluid coupling effect) is a universal factor. As noted in Refs [6.4.3, 6.4.5], the fluid forces can reach rather large values in closely spaced rack geometries.
It is, therefore, essential that the contribution of the fluid forces be included in a comprehensive manner for the spent fuel pool analyses.Holtec Report HI-2115004 6-16 Holtec Project 2119 1 The derivation of the fluid coupling matrix [6.4.3] relies on the classical inviscid fluid mechanics principles, namely the principle of continuity and Kelvin's recirculation theorem. While the derivation of the fluid coupling matrix is based on no artificial construct, it has been nevertheless verified by an extensive set of shake table experiments
[6.4.3].In its simplest form, the so-called "fluid coupling effect" [6.4.4, 6.4.5] can be explained by considering the proximate motion of two bodies under water. If one body (mass inm) vibrates adjacent to a second body (mass M 2), and both bodies are submerged in frictionless fluid, then Newton's equations of motion for the two bodies are: (ml + M 1 1) A I + M 1 2 A 2 = applied forces on mass inm + 0 (XI 2)M 2 1 A, + (M2 + M 2 2)A 2 = applied forces on mass m2 + 0 (X 2 2)A 1 , A 2 denote absolute accelerations of masses ml and m2, respectively, and the notation O(X 2)denotes nonlinear terms.M 1 1 , M 1 2 , M21, and M 2 2 are fluid coupling coefficients which depend on body shape, relative disposition, etc. Fritz [6.4.5] gives data for Mij for various body shapes and arrangements.
The fluid adds mass to the body (M 1 1 to mass in 1), and an inertial force proportional to acceleration of the adjacent body (mass M 2). Thus, acceleration of one body affects the force field on another.This force field is a function of inter-body gap, reaching large values for small gaps. Lateral motion of a fuel assembly inside a storage location encounters this effect. For example, fluid coupling behavior will be experienced between nodes 2 and 2* in Figure 6.4.1. The rack analysis also contains inertial fluid coupling terms, which model the effect of fluid in the gaps between adjacent racks.Rack-to-rack gap elements have initial gaps set to 100% of the physical gap between the racks or between outermost racks and the adjacent pool walls.6.4.3 Governing Equations of Motion Holtec Report HI-2115004 6-17 Holtec Project 2119 1 Using the structural model discussed in the foregoing, equations of motion corresponding to each degree-of-freedom are obtained using Lagrange's Formulation
[6.4.2]. The system kinetic energy includes contributions from solid structures and from trapped and surrounding fluid. The final system of equations obtained has the matrix form:[d2 q] Q + [G]where:[M] is the total mass matrix (including structural and fluid mass contributions).
The size of this matrix will be 22n x22n for a WPMR analysis (n = number of racks in the model).q is the nodal displacement vector relative to the pool slab displacement (the term with q indicates the second derivative with respect to time, i.e., acceleration)
[G] is a vector dependent on the given ground acceleration
[Q] is a vector dependent on the spring forces (linear and nonlinear) and the coupling between degrees-of-freedom The above column vectors have length 22n. The equations can be rewritten as follows: d q]=[M]- [-1 d'-t2 [ ]I[ +[M [G]This equation set is mass uncoupled, displacement coupled at each instant in time. The numerical solution uses a central difference scheme built into the Holtec-proprietary computer program DYNARACK [6.4.2].Holtec Report HI-21 15004 6-18 Holtec Project 2119 I Holtec Report HI-2115004 6-18 Holtec Project 2119 1 6.5 Key Input Data for Dynamic Analysis 6.5.1 Rack data The various components for each of the rack styles are described in detail in Chapter 2. The rack model prepared for the DYNARACK simulations incorporates all of the pertinent features and characteristics of each replacement rack. Rack material properties, extracted from the ASME Codes [6.2.7] are summarized in Table 6.5.1.The cartesian coordinate system utilized within the dynamic models has the following orientation:
x = Horizontal axis along plant North (in a north-south direction) y = Horizontal axis along plant East (in an east-west direction) z = Vertical axis upward from the rack base 6.5.2 Synthetic Time-Histories Synthetic time-histories in three orthogonal directions (N-S, E-W, and vertical) are generated in accordance with the provisions of Section 3.7.1 of the Standard Review Plan (SRP) [6.2.3]. In order to prepare an acceptable set of acceleration time-histories, the Holtec-proprietary code GENEQ [6.5.1] is utilized.
As required by SRP 3.7.1 [6.2.3], the code GENEQ was used to develop five sets of acceleration time histories for the design basis response spectra.The following criteria required by SRP 3.7.1 have been satisfied:
: 1. Each time history set (2 horizontal and I vertical) must be statistically independent.
This is demonstrated by calculating the cross correlation coefficient for each time history with each of the other two events. The absolute value of each of the three correlation coefficients must be less than 0.16.2. The following requirements apply to each of the time histories:
Holtec Report HI-2115004 6-19 Holtec Project 2119 1
* The time history shall have a sufficiently small time increment and sufficiently long duration.
Records shall have a Nyquist frequency of at least 50 Hz, (e.g., a time increment of at most 0.0 10 seconds) and a total duration of at least 20 seconds.* Spectral acceleration at 2% damping shall be computed at a minimum of 100 points per frequency decade, uniformly spaced over the log frequency scale from 0.1 Hz to 50 Hz or the Nyquist frequency.
The comparison of the response spectrum obtained from the artificial ground motion time history with the target response spectrum shall be made at each frequency computed in the frequency range of interest.3. The following requirements apply to each of the average response spectra: " The computed 2% damped, average response spectrum for the set of 5 accelerograms shall not fall more than 10% below the target response spectrum per the criteria specified in SRP 3.7.1.* The computed 2% damped, average response spectrum shall not exceed the target response spectrum at any frequency by more than 30% (a factor of 1.3) in the frequency range of interest.
If the average response spectrum for the accelerograms exceeds the target response spectrum by more than 30% at any frequency range, the power spectrum density (PSD) functions of the accelerograms need to be computed, and the average PSD function must be shown to not have significant gaps in energy over the frequency range of interest.The 2% damped response spectra are used to satisfy the response spectrum enveloping requirements of SRP 3.7.1 since 2% of critical damping is specified in the Palisades FSAR for welded steel frame assemblies.
Holtec Report HI-2115004 6-20 Holtec Project 21.19 1 The code GENEQ [6.5.1] is used to develop the acceleration-time history sets based on the floor response spectra at El. 611'. One set of acceleration time histories consists of three component directions.
Figure 6.5.1 shows the SSE acceleration time histories in the east-west direction for all five sets.Figure 6.5.2 shows the comparison between, the target response spectra and the regenerated spectra for the 2% damped SSE event in the east-west direction for all five sets. Figure 6.5.3 shows the comparison between the target response spectra and the average of five regenerated response spectra for the 2% damped SSE event in the east-west direction.
Figure 6.5.4 shows the comparison between the target PSD function and the average of five regenerated PSD functions for the 2% damped SSE event in the east-west direction.
The acceleration-time history plots, individual response spectrum plots, average response spectrum, and PSD functions for the north-south direction are shown in Figures 6.5.5, 6.5.6, 6.5.7 and 6.5.8, respectively.
Figures 6.5.9, 6.5.10, 6.5.11 and 6.5.12 correspond to the vertical direction.
All governing criteria for development of multiple sets of synthetic acceleration-time histories for use in seismic analysis are thus considered to be satisfied, and the generated seismic accelerograms are suitable to simulate the seismic event for the freestanding racks.1-loltec Report HI-21 15004 6-21 Holtec Project 2119 I I Holtec Report HI-2115004 6-21 Holtec Project 2119 1 6.6 Dynamic Simulations for the Palisades SFP As shown in Figure 1.1.1, the proposed rerack campaign will result in the installation of six Region 1 racks in the main SFP and a single rack in the North Tilt Pit (NTP). Two separate WPMR models are developed for the SFP and the NTP, and a total of eleven runs with fully loaded racks and random coefficients of friction are performed.
Run numbers 1 through 5 are associated with the SFP, and each run includes all six Region 1 racks in the model. Run numbers 6 through 10 are associated with the NTP, and each run includes only one rack (i.e., rack N7) in the model. Finally, run number 11 considers the most limiting interim rack storage configuration during the installation sequence.
In particular, run number 11 includes only two fully loaded Region 1 racks in the model, as shown in Figure 6.6.1. This configuration is most limiting because it has two fully loaded racks isolated at the South end of the SFP. The large fluid gap to the North of these racks significantly reduces the fluid coupling effects and makes these racks vulnerable to increased rocking motion under SSE conditions.
All eleven runs are summarized below: Holtec Report HI-2 115004 6-22 Holtec Project 2119 I Holtec Report HI-2115004 6-22 Holtec Project 2119 i Location Run Number Seismic Input 1 Set I 2 Set 2 Spent Fuel 3 Set 3 Pool 4 Set 4 5 Set 5 11 Bounding Set from Sets 1 to 5 6 Set 1 7 Set 2 North Tilt 8 Set 3 Pit 9 Set 4 10 Set 5 The simulations consider SSE excitation and are required to satisfy the stress and kinematic criteria in Section 6.2. The calculated stresses from the SSE simulations are compared against the allowable stresses corresponding to ASME Service Level D (see Subsection 6.2.3.1.2).
No time history simulations are performed for OBE loading. In lieu of performing OBE simulations, the minimum calculated safety factors for the SSE simulations must exceed 1.8 for weld and base metal shear and 2.0 for tension, compression, bending, and combinations thereof. This approach is justified, and insures that OBE load combinations are not controlling, because: i) OBE is equal to 1/2/ of SSE per Section 5.7.1.2 of the Palisades FSAR [6.6.2];ii) the allowable stresses for ASME Level D are equal to 2 times the allowable stresses for ASME Level A (excluding shear stress) (see Subsection 6.2.3.1.2);
iii) the allowable shear stress for ASME Level D is equal to 1.8 times the allowable shear stress for ASME Level A (see Subsection 6.2.3.1.2);
iv) the same damping value applies to OBE and SSE per Table 5.7-2 of the Palisades FSAR [6.6.2].Holtec Report HI-2115004 6-23 Holtec Project 2119 1 The multi-rack model prepared in the manner of the preceding sections, is subjected to each of the five sets of the three dimensional time history acceleration.
The maximax (maximum in time and space) response of the rack modules under each of the five time history sets is summarized in Table 6.6.1 and 6.6.2 (extracted from the Holtec calculation package [6.6.1]).Rack N7 in the NTP is modeled as a freestanding autonomous module with the interactive effect of fluid coupling from the surrounding structures appropriate for deeply submerged components.
The response of the rack under each of the five time history sets is summarized in Table 6.6.1 and 6.6.2.Holtec Report HI-2115004 6-24 Holtec Project 2119 1 6.7 Compliance with the Acceptance Criteria under the Seismic Loads The results from the DYNARACK runs are summarized in the tables referenced in the preceding section by extracting the worst case values for the parameters of interest; namely displacements, support pedestal forces, impact loads, and stress factors. This section provides a discussion of the DYNARACK results and summarizes the additional ancillary analyses performed to demonstrate compliance with the acceptance criteria presented in Section 6.2.6.7.1 Rack Displacements and Kinematic Stability Determination The displacement results provided in Tables 6.6.2 show that maximax displacements are limited to 0.6952 inch at the top and 0.0404 in at the baseplate elevation of the rack array. The above bounding values of the computed rack displacement indicate that the modules hardly move at all and that there will be no rack-to-rack impacts in the cellular region. Likewise, no impact between the peripheral racks and proximate pool structures is indicated.
The maximum lateral movement of the pedestal, limited to less than 0.1 inch, as indicated by Table 6.6.2, provides the firm assurance that the rack pedestals will not slide off their bearing pads.6.7.2 Fuel Rattling Loads The bounding fuel-to-cell wall impact load, at any level in the rack, for all runs is less than 800 lb (see Table 6.6.1). For the five-lumped mass model (with 25% at the 1/4 points and 12.5% at the ends), the maximum g-load that the rack imparts on the fuel assembly can be computed as: 4F a --2.21g w where: a maximum lateral acceleration in g's F = maximum fuel-to-cell wall impact force (= 800 lbf)w = weight of one fuel assembly (conservatively taken to be 1,450 lbf)Holtec Report HI-2115004 6-25 Holtec Project 2119 1 The maximum lateral acceleration is an order of magnitude less than the impact decelerations that fuel assemblies are typically qualified for in cask transport applications (60 g's), as set down in Section 6.2. Therefore, the structural integrity of the fuel assemblies under an SSE event is assured.6.7.3 Storage Cell Deformation Even though limits on secondary stresses are not prescribed in the ASME Code for Class 3 NF structures, analysis has been performed in support of this safety evaluation to insure that the localized impacts do not lead to significant plastic deformations in the storage cell walls which may affect the sub-criticality of the stored fuel array. Classical strength of materials calculations show that the primary stresses in the cell wall under the lateral impact load from the rattling of the fuel assemblies remains in the elastic range. Thus a plastic deformation of the cell wall from the rattling action of fuel during a seismic event is ruled out.For reference purposes, the limit load on the cell wall that will produce a plastic hinge is computed to determine the margin of safety at which a reactivity-significant deformation of the cell wall would be considered to occur. This limit load is computed to be 3,451 lbs which, against the peak computed rattling load of 760 lbs (from Table 6.6.1), indicates a robust factor of safety of approximately 4.54.6.7.4 Rack-to-Rack and Rack-to-Wall Impacts In order to protect the rack cellular structure from impact during a seismic event and maintain the installed inter-rack spacing, the rack baseplates extend beyond the perimeter envelope of the cell region. The racks are then installed in the pool with the baseplates edges contiguous to each other in conformal contact to the extent practicable.
Therefore, by design the racks are predisposed to impact each other at the baseplate level during a seismic event, rather than at the top of rack elevation.
The thick baseplates used in the rack modules are thus subject to sporadic impact loads during the earthquake.
Holtec Report HI-2115004 6-26 Holtec Project 2119 1 The results from the DYNARACK simulations indicate that the in-plane impact load in the baseplates is less than 10,000 lbs. Since the impact load occurs simultaneously at two contact springs on one side of the rack, it is reasonable to consider the impact load is distributed over the length of the baseplate edge. The bearing stress is conservatively calculated as 10,000 lbs/(l in x 80.68 in) = 124 psi, which is much less than even the level A bearing stress limit (which is 0.9XSy = 19,170 psi).6.7.5 Rack Stress Factors The time history results from the DYNARACK solver provide the pedestal normal and lateral interface forces, which may be converted to the limiting bending moment and shear force at the bottom baseplate-to-pedestal interface.
In particular, maximum values for the previously defined stress factors are determined for every pedestal in the array of racks. The net section maximum (in time) bending moments and shear forces can also be determined at the bottom baseplate-to-rack cellular structure interface for each spent fuel rack in the pool. Using these forces and moments, the maximum stress in the limiting rack cell (box) can be evaluated.
In Table 6.6.1, the maximum stress factors are those that occur in the pedestals for each run, which bound the stress factor in the rack cell wall. As can be seen from the table, all stress factors, as defined in Section 6.2, are less than the half of the mandated limit of 1.0 for all racks for the governing faulted condition examined.
Therefore, the structural integrity of the rack modules under seismic events is demonstrated.
6.7.6 Pedestal Thread Shear Stress The vertical load on the rack pedestal from the universe of WPMR analysis runs, per Table 6.6.1, is less than 110,000 lbs.Holtec Report HI-2115004 6-27 Holtec Project 2119 1 Using this value the maximum average shear stress in the engagement region is calculated using the formula in [6.7.2].F Sthread A n A n e iL D + I (D -E mi 1n 3 min max Where: F = Maximum vertical force.A = Thread engagement area.n n = Threads per inch = 4 L = Engagement length = 3.5 in.e D = Minimum major dia., external thread = 4.9964 in.Smin E = Maximum pitch dia., internal thread = 4.8530 in.max S thread 2,409 psi. This computed stress is bounding for both the exterior and interior pedestal threads, and the associated factor of safety is tabulated below: Shear Stress (psi) Allowable stress (psi) Safety Factor 2,409 15,408 6.396 6.7.7 Weld Stresses Weld locations in the rack modules are locations that resist seismic loading are at the bottom of the rack at the baseplate-to-cell connection, at the top of the pedestal support at the baseplate connection, and at the cell-to-cell connections.
Bounding values of seismic reaction loads are used to qualify the weld joints.ASME Code Section III, Subsection NF permits, for Level A or B conditions, an allowable weld stress c = 0.3S,. Conservatively assuming that the weld strength is the same as the lower base Holtec Report HI-2115004 6-28 Holtec Project 2119 1 metal ultimate strength, the allowable stress is given by t = 0.3 x (66,100) = 19,830 psi. Per Subsection 6.2.3.1.2 (item d), the allowable for Level D is 0.54S,, giving an allowable of 35,694 psi.a. Baseplate-to-Rack Cell Welds The rack's cellular structure is connected to the base plate through fillet welds that are typically 6 inches long. The maximum values of the tensile stresses in the connecting welds and the adjacent base metal is computed using the maximax values of the stress factors from the DYNARACK simulations.
The table below shows the stress in weld and base metal along with the associated factors of safety (allowable is 1.0 minimum).Allowable stress (psi) Safety Factor Stress (psi)Weld 10,896 35,694 3.276 Base Metal 6,552 15,408 2.351 b. Baseplate-to-Pedestal Welds The shear load on any pedestal for all runs is less than 35,000 lbs per Table 6.6.1. This bounding shear load is used as input to evaluate the integrity of the pedestal-to-baseplate weld.The rack weld between baseplate and support pedestal is checked using conservatively imposed bounding loads in a separate finite element model. ANSYS is used to resolve the tension and compression stresses in the pedestal weld due to the combined effects of a vertical compressive load in the pedestal and a bending moment caused by pedestal friction.
The limiting ANSYS results are combined with the maximum horizontal shear loads to obtain the maximum weld stress.Holtec Report HI-2115004 6-29 Holtec Project 2119 1 The maximum shear force, as derived from the DYNARACK, is determined to be less than 35,000 lbs. Conservatively, this shear force is also applied in other orthogonal direction.
These two forces are applied in two directions (x and y) simultaneously.
The maximum pedestal compressive force is determined to be bounded by 110,000 lbs. This force is also applied to the finite element model. The table below shows that the stress in weld and base metal is acceptable and that the safety factors are greater than 1.0.Allowable stress (psi) Safety Factor Stress (psi).Weld 9,497 35,694 3.758 Base Metal 6,716 15,408 2.294 c. Cell-to-cell welds Cell-to-cell joints consist of a series of connecting welds along the cell height. Stresses in storage cell to cell welds develop due to fuel assembly impacts with the cell wall. These weld stresses are conservatively calculated by assuming that fuel assemblies in adjacent cells are moving out of phase with one another so that impact loads in two adjacent cells are in opposite directions thus maximizing the stress in the connecting longitudinal welds. Both the weld and the base metal shear stress results using the strength-of-materials solution process are summarized below: Analysis Type Stress (psi) Allowable stress (psi) Safety Factor Weld 2,813 35,694 12.69 Base metal shear 1,989 15,408 7.75 6.7.8 Assessment of Rack Fatigue Margin Holtec Report HI-2115004 6-30 Holtec Project 2119 1 Alternating stresses in metals produce metal fatigue if the amplitude of the stress cycles is sufficiently large. In high-density racks designed for sites with moderate to high postulated seismic action, the stress intensity amplitudes frequently reach values above the material endurance limit, leading to expenditure of the fatigue "usage" reserve in the material.Because the locations of maximum stress (viz., the pedestal/rack baseplate junction) and the close placement of racks, a post-earthquake inspection of the high stressed regions in the racks is not feasible.
Therefore, the racks must be engineered to withstand multiple earthquakes without reliance on nondestructive inspections for post-earthquake integrity assessment.
ASME subsection NF does not require a fatigue evaluation for Class 3 linear-type supports, which is the applicable code for rack design. However, for conservatism, the analysis method that is implemented is briefly summarized here, as it is applied to fuel storage racks.The time-history method of analysis, deployed in this report, provides the means to obtain a complete cycle history of the stress intensities in the highly stressed regions of the rack. Having determined the amplitude of the stress intensity cycles and their number, the cumulative damage factor, U, can be determined using the classical Miner's rule: Ni where ni is the number of stress intensity cycles of amplitude cYi, and Ni is the permissible number of cycles corresponding to ai from the ASME fatigue curve for the material of construction.
U must be less than or equal to 1.0.For the storage fuel racks, the geometry and loading are such that the areas of concern are (i) the threaded connection between the inner and outer support pedestals, and (ii) the weld connection between the rack cell walls and the baseplate.
Based on the maximum stress at the weld location of 10,896 psi and the maximum compressive stress in the pedestal of 5,659 psi (based on maximum pedestal load 110,000 lbf), the resulting amplified alternating stress intensity is 19,066 Holtec Report HI-2115004 6-31 Holtec Project 2119 i psi. Table 1.9-1 of the ASME Code [6.2.6] shows that the endurance limit (corresponding to 1E+06 cycles) is 28.3 ksi. Therefore, there is no risk of fatigue failure from oscillating stresses in the rack structure under multiple earthquakes.
6.7.9 Potential for Cell Wall Buckling The allowable local buckling stresses in the fuel cell walls (from vertical loading) are obtained by using classical plate buckling analysis on the lower portion of the cell walls. The following formula for the critical buckling stress is applicable.
Cr 1-2  b)where E = 27.5 x 106 psi, u is Poison's ratio = 0.3, t = .090", b = 8.75". The K factor varies depending on the plate length/width ratio and the boundary support conditions at the sides of the plate. At the base of the rack, the cell wall acts alone in compression for a length of about 3.5" up to the point where the poison sheathing is attached.
For all four side edges simply supported plate, the K value is given by Table 35 of [6.7.1] to be 6.92.For the given data, ccr = 22,204 psi, which is larger than the yield strength for the rack cell wall material (Table 6.5.1).This local buckling stress limit is not violated anywhere in the body of the rack modules, since the maximum compressive stress in the outermost cell is= 1.2
* Sy
* R6 (see Section 6.2.3.2) (1.2)(21,300 psi)(0.140)
= 3,578 psi which is obviously smaller than 2/3 acr. Therefore, the buckling is not a concern.Holtec Report HI-21 15004 6-32 Holtec Project 2119 I Holtec Report HI-2115004 6-32 Holtec Project 2119 1 6.8 Evaluation of Steady State Conditions 6.8.1 Primary Stresses under Dead Load Conditions The dead load is treated as a level A (ASME Code) service condition for fuel racks .As would be expected, the dead load is not a governing condition for the Palisades rack modules which, because of their honeycomb construction (described in Chapter 2) emulate a deep multi-flanged beam. The basic dead load data for the heaviest rack module is summarized below: LEVEL A MAXIMUM PEDESTAL LOAD Dry Weight of 8 x 8 Rack -Dry Weight of 64 Intact Fuel Assemblies Total Dry Weight -Load per Pedestal =18,000 lbf 92,800 lbf 110,800 lbf 27,700 lbf It is noted from the above that the load per pedestal is approximately 30% of the seismic load (Table 6.6.1). Therefore, since the Level A loads are approximately 30% of the Level D loads, while the Level A limits equal or exceed 50% of the Level D limits, the SSE load condition bounds the dead load condition and the structural integrity of the rack modules under the dead load condition is satisfied with a large margin.Holtec Report HI-21 15004 6-33 Holtec Project 2119 I Holtec Report HI-2115004 6-33 Holtec Project 2119 i 6.8.2 Analysis of Thermal Effects Although racks are considered a Class 3 "NF" compliant structure (which do not require consideration of secondary stresses) a special case of an adverse thermal stress field that can develop in the pool is considered herein to establish safety from weld failure in the cellular region of the racks .The cell-to cell welded joints, as can be ascertained from physical reasoning, are subject to shear stresses if the adjacent storage cells are in contact with pool water at different temperatures.
The most severe thermal gradient between cells will develop when an isolated storage location contains a fuel assembly emitting maximum postulated heat, while the surrounding locations are empty. A conservative estimate of weld stresses along the length of an isolated hot cell can be obtained by considering a beam strip uniformly heated by 50'F, which is restrained from growth along one long edge. The above thermal gradient is based on the results of the thermal-hydraulic analysis, which shows that the difference between the local cell maximum temperature (168&deg;F)and the bulk pool temperature (124&deg;F) is less than this value.Using shear beam theory and subjecting the strip to a uniform temperature rise AT = 50'F, one can calculate an estimate of the maximum value of the average shear stress in the strip. The strip is subjected to the following boundary conditions.
: a. Displacement Ux (x,y) = 0 at x = 0, at y = H/2, for all x.b. Average force Nx (x) = 0 at x = L The final result for wall shear stress, maximum at x = L, is found to be given as EaAT* Tmax-03-0.931 where E = 27.5 x 10 6 psi, (x = 9.5 x 10-6 in/in 'F and AT = 50'F.Holtec Report HI-21 15004 6-34 Holtec Project 2119 I I Holtec Report HI-2115004 6-34 Holtec Project 2119 1 Therefore, the maximum shear stress in an isolated hot cell, due to thermal gradient, is Tmax = 14,030 psi Strictly speaking thermal stresses do not require evaluation under Subsection NF per NF-3121.11 [6.2.5]. However, for conservatism, the above calculated stress is compared against the primary plus secondary stress limit per Table NF-3523(b)-l of the ASME Code [6.2.5].Specifically, the stress limit is the lesser of 2Sy or Su at the applicable temperature.
For SA-240 304L material, the limit is controlled by 2Sy, which equals 42,800 psi based on the material yield strength given in Table 6.5.1. Therefore, there is a safety factor = 42,800 / 14,030 = 3.05 against cell wall shear failure due to secondary thermal stresses from cell wall growth under the worst case hot cell condition.
Holtec Report HI-21 15004 6-35 Holtec Project 2119 Holtec Report HI-2115004 6-35 Holtec Project 2119 1 6.9 Oualification of the Bearing Pad and Bearing Pressure on the Pool Slab Bearing pads are placed between rack pedestals and the SFP floor to reduce the compressive stresses on the SFP concrete slab by spreading the concentrated load of each pedestal over a larger contact area. This evaluation demonstrates that under maximum vertical forces in seismic events, the average compressive stress in the underlying concrete (calculated over the net bearing pad area) remains below the allowable value permitted by the American Concrete Institute, ACI 318-71 [6.9.1].A bearing pad will be installed beneath all of the support pedestals on the new Region I racks in the SFP and the Tilt Pit. The nominal size of the bearing pad, which is made from SA-240 304L material, is 14" x 14" x 4" thick.The bearing stress in the underlying concrete is calculated by dividing the maximum pedestal load (including ACI load factors) by the net bearing pad area, which is defined as the total bearing pad area (i.e., pad length x pad width) minus the intersecting leak chase area beneath the bearing pad. For conservatism, the maximum calculated pedestal load from Table 6.6.1 is multiplied by a bounding load factor of 1.7 to ensure that the ultimate strength requirements from ACI 318-71 [6.9.1] are met. The calculated bearing stress is 1.7 x 90,6001bf (14 x 14 -14 x 1.625)in 2 =889psi The bearing pads adequately diffuse the peak pedestal load so that the compressive stress in the concrete slab is below the limit set by the governing concrete code [6.9.1] based on the design minimum concrete compressive strength of 3,000 psi. The results are summarized in the following table.Holtec Report HI-2 115004 6-36 Holtec Project 2119 Holtec Report HI-2115004 6-36 Holtec Project 2119 i Calculated Bearing Stress on Allowable Bearing Stress (psi) (from Safety Factor the pool slab (psi) Section 6.3)889 3,570 4.01 Holtec Report HI-2 115004 6-37 Holtec Project 2119 I Holtec Report HI-2115004 6-37 Holtec Project 2119 i 6.10 References
[6.1.1] "Management of Spent Nuclear Fuel", Tony Williams and K.P. Singh, Companion Guide to the ASME Boiler & Pressure Vessel Code, Third Edition, April 2009, ed., K.R. Rao, Volume 3, Chapter 56, pp 433-453.[6.1.2] Soler, A.I. and Singh, K.P., "Seismic Responses of Free Standing Fuel Rack Constructions to 3-D Motions", Nuclear Engineering and Design, Vol. 80, pp. 315-329 (1984).[6.1.3] Singh, K.P. and Soler, A.I., "Seismic Qualification of Free Standing Nuclear Fuel Storage Racks -the Chin Shan Experience, Nuclear Engineering International, UK (March 1991).[6.1.4] Soler, A.I. and Singh, K.P., "Some Results from Simultaneous Seismic Simulations of All Racks in a Fuel Pool", INNM Spent Fuel Management Seminar X, January, 1993.[6.1.5] ISG-2 1, Rev 0 " Use of Computer Modelling Software", USNRC, April 2006.[6.2.1] NUREG/CR-1864, "A Pilot Probabilistic Risk Assessment of a Dry Cask Storage System at a Nuclear Power Plant", USNRC, Washington D.C., 2007.[6.2.2] Safety Analysis Report for HI-STAR 100 Dual Purpose Cask", USNRC Docket number 71-9261, USNRC, Washington D.C. (1999).[6.2.3] USNRC NUREG-0800, Standard Review Plan, March 2007, (SRP 3.8.4 Rev. 2) and (SRP 3.7.1 Rev 3).[6.2.4] Not Used.[6.2.5] ASME Boiler & Pressure Vessel Code, Section III, Subsection NF, 1998 Edition.Holtec Report HI-2115004 6-38 Holtec Project 2119 1
[6.2.6] ASME Boiler & Pressure Vessel Code, Section III, Appendices, 1998 Edition.[6.2.7] ASME Boiler & Pressure Vessel Code, Section II, Part D, 2010 Edition.[6.4.1] Rabinowicz, E., "Friction Coefficients of Water Lubricated Stainless Steels for a Spent Fuel Rack Facility," MIT, a report for Boston Edison Company, .1976.[6.4.2] Validation Manual for Computer Code DYNARACK, Holtec Proprietary Reports HI-961465 & HI-91700.[6.4.3] Paul, B., "Fluid Coupling in Fuel Racks: Correlation of Theory and Experiment", (Proprietary), NUSCO/Holtec Report HI-88243.[6.4.4] Singh, K.P. and Soler, A.I., "Dynamic Coupling in a Closely Spaced Two-Body System Vibrating in Liquid Medium: The Case of Fuel Racks," 3rd International Conference on Nuclear Power Safety, Keswick, England, May 1982.[6.4.5] Fritz, R.J., "The Effects of Liquids on the Dynamic Motions of Immersed Solids," Journal of Engineering for Industry, Trans. of the ASME, February 1972, pp 167-172.[6.4.6] Levy, S. and Wilkinson, J.P.D., "The Component Element Method in Dynamics with Application to Earthquake and Vehicle Engineering," McGraw Hill, 1976.[6.5.1 ] Holtec Proprietary Report HI-893 64, Verification and User's Manual for Computer Code GENEQ, January 1990.[6.6.1 ] Holtec Proprietary Report HI-2115014, Structural/Seismic Analysis of Palisades Region 1 Spent Fuel Racks, 2012.[6.6.2] Palisades FSAR, Revision 29.Holtec Report HI-2115004 6-39 Holtec Project 2119
[6.7.1 ] Theory of Elastic Stability, Timoshenko and Gere, 2nd Edition, 1961, McGraw Hill.[6.7.2] E. Oberg et al., 27th Edition," Machinery's Handbook", Industrial Press Inc., 2004.[6.9.1] American Concrete Institute, Building Code requirements for Structural Concrete," ACI 318-71, Detroit, Michigan, 1971.Holtec Report HI-21 15004 6-40 Holtec Project 2119 I Holtec Report HI-2115004 6-40 Holtec Project 2119 1 Table 6.4.1 PARTIAL LISTING OF FUEL RACK APPLICATIONS USING DYNARACK PLANT DOCKET NUMBER(s)
YEAR Enrico Fermi Unit 2 USNRC 50-341 2000 Kewaunee USNRC 50-305 2001 V.C. Summer USNRC 50-395 2001 St. Lucie USNRC 50-335, 50-389 2002 Turkey Point USNRC 50-250, 251 2002 Clinton USNRC 50-461 2003 ANO Units 1 & 2 USNRC 50-313,50-368 2003 Diablo Canyon Unit 1 & 2 USNRC 50-275, 50-323 2004 Cooper USNRC 50-298 2006 Beaver Valley Unit 2 USNRC 50-412 2011 Holtec Report 141-2115004 6-41 Holtec Project 2119 I Holtec Report HI-2115004 6-41 Holtec Project 2119 i Table 6.4.2 DEGREES-OF-FREEDOM LOCATION (Node) DISPLACEMENT ROTATION Ux Uy Uz 0x Oy 0z pi P2 P3 q4 q5 q6 2 P7 P8 P9 q10 q_ _ q12 Node 1 is attached to the rack at the bottom most point.Node 2 is attached to the rack at the top most point.Refer to Figure 6.4.1 for node identification.
2 P13 P14 3 P15 P16 4 P17 pig 5*5 p19 P20 1 P21 P22 where the relative displacement variables qi are defined as: pi qi(t) + U.(t) i = 1,7,13,15,17,19,21
-qi(t) + Uy(t) i = 2,8,14,16,18,20,22
= qi(t) + Uz(t) i = 3,9-qi(t) i = 4,5,6,10,11,12 pi denotes absolute displacement (or rotation) with respect to inertial space qi denotes relative displacement (or rotation) with respect to the floor slab* denotes fuel mass nodes U(t) are the three known earthquake displacements Holtec Report HI-2115004 6-42 Holtec Project 2119 1 Table 6.5.1 RACK MATERIAL DATA (200&deg;F)(ASME -Section II, Part D)Young's Modulus Yield Strength Ultimate Strength Material E Sy Su (psi) (psi) (psi)SA240, Type 304L 27.5 x 106 21,400 66,100 SUPPORT MATERIAL DATA (200&deg;F)SA240, Type 304L (upper 27.5 x 106 21,400 66,100 part of support feet)SA-564-630 (lower part of 27.8 x 106 106,300 140,000 support feet; age hardened at 1 100oF)Holtec Report HI-2115004 6-43 Holtec Project 2119 1 Table 6.6.1 Maximum Values of Stress Factors and Impact Loads Max.Stress Max. Max. Shear Max Run Factor Vertical Load on Single Fuel to Cell No. (defined Load on Single Pedestal (lbf) Wall Impact in Section Pedestal (lbf) (X or Y) (lbf)6.2)1 0.121 83,300 24,500 675 2 0.119 90,600 25,300 698 Spent 3 0.117 86,200 24,200 669 Fuel Pool 4 0.122 76,200 28,000 760 5 0.140 86,000 31,800 720 11 0.118 84,100 22,800 709 6 0.095 72,600 25,300 592 7 0.099 70,600 25,600 552 Tilt Pit 8 0.092 70,100 25,800 632 9 0.092 69,600 27,100 522 10 0.101 81,700 22,800 700 Holtec Report HI-2115004 6-44 Holtec Project 2119 1 Table 6.6.2 Maximum Values of Lateral Displacements Maximum Rack displacement Run relative to floor (inch) No Spent Base Plate 0.0164 5 FuelPool Top of Rack 0.3028 5 North Base Plate 0.0404 10 Tilt Pit Top of Rack 0.6952 10 Holtec Report HI-2 115004 6-45 Holtec Project 2119 Holtec Report 1-11-2115004 6-45 Holtec Project 2119 1 Figure 6.4.1 -Single Rack Dynamic Model Holtec Report HI-2115004 6-46 Holtec Project 2119 1 Figure 6.4.2 -Fuel-to-Rack Impact Springs Holtec Report HI-2115004 6-47 Holtec Project 2119 1 FRICTIUN H/4 WNERFAC____
SPRING, Kf A A.KKsU SFPiemt LEG SPRMNG Ks/7`77 Figure 6.4.3 D Schematic Elevation of the Storage Rack Model Holtec Report HI-2115004 6-48 Hottec Project 2119 1 Ksy RACK DEGREES-OF-FREEDOM FOR Y-Z PLANE BENDING WVIT SHEAR AND SPRNG q, KU Knr Figure 6.4.4 -Rack Degrees of Freedom and Modeling Technique Holtc Rpor HI2 110046-4 IlltecProect211 Holtec Report HI-2115004 6-49 Holtec Project 2119 i TYPICAL TOP IMPACT ELEMENT TYPICAL BTTOM IMPACT ELEMENT.RACK STRUCTURE Figure 6.4.5 D Inter-Rack Impact Springs Holtec Report HI-2115004 Holtec Report HI-2 115004 6-50 1-loltec Project 2119 I 6-50 Holtec Project 2119 1 04 Pahsades SSE in E-W Direction Set 1 02 00 04 1 1 III Palisades SSE in E-W Direction.
Set 2 02-g-r 1111 1 00-02-02-04-- ------- --- ------T I.. .. ... -_ -----------------
.10 20 Time (sec)-04-Iri 04 02 00-02-04'5 0 10 Time )sec)04 -Palisades SSE in E-W Directon.
Set 4 02 00-02 4-04 0 10 Time nsec)20 04 Time (sec)FPalisades SSE in E-W Direction, Set 5-04 0 10 20 Time (sec)Figure 6.5.1 -Generated Acceleration Time History in E-W Direction, Sets 1 to 5 Holtec Report HI-2 115004 6-51 Holtec Project 2119 I Holtec Report HI-2115004 6-51 Holtec Project 2119 1 35 ----Target -- --....Target Set 1 3.5 Set 2 -3 3 2.5 2.5 or, 2 or.,_ ___= 2 1. 1.5 0.5 -0.5 --.0 0 0.1 1 10 100 0.1 1 10 100 Frequency (Hz) Freqxiency (Hz)--. -Target 3 .5 -Target 33 -Set 4 2.5 2.5 2 ~, 2 1.5 ....01.5 0 01 0. --------- 0 .5 --0.1 1 10 100 0.1 1 10 100 Frequency (Hz) Freqpuency (Hz).... Target_____Set5 S 3-2.5 -2 _0.5 0 0.1 1 10 100 Frequency (Hz)Figure 6.5.2 -Target and Generated Response Spectra in E-W Direction, Sets 1 to 5 Holtec Report 111-2115004 6-52 Holtec Project 2119 I Holtec Report HI-2115004 6-52 Holtec Project 2119 1 I Response Spectra, Palisades SSE in E-W Direction, Average I 3.5 3 2.5"" 2 1.5 1 0.5 0 0.1 1 10 100 Frequency (Hz)Figure 6.5.3 -Target and Average of Generated Response Spectra in E-W Direction I PSD, Palisades SSE in E-W Direction, Average 1000 100 9::1 10 1 0.1 0.01 0.001 0.1 1 10 100 Frequency (Hz)Figure 6.5.4 -Target and Average of Regenerated PSD in E-W Direction Holtec Report 111-2115004 6-53 Holtec Project 2119 I Holtec Report HI-2115004 6-53 Holtec Project 2119 1 U 4, 04 i Paiis4esSS.nN.S eCdon, SO 1 00 0 10 20 Time (sae)04 Palisades SSE in N-S Drectdon.
Set 3 02 00 04 02 t,, I00-02-04[Viisads SSE in N-S Direc SO 2 0 10 Tiff* (w), 04 -Palisades SSE in N.Sq~cnS 02 --0 0 20 I ,9 002-04-02-04 04 00 10 Tim@ (sei)PataeSEin M-S DiretOn. so~ 5 20 0 10 20 Time (W)S I 4-0 2-04 0 10 20 Time (sKc)Figure 6.5.5 -Generated Acceleration Time History in N-S Direction, Sets 1 to 5 Holtec Report 141-2115004 6-54 Holtec Project 2119 I Holtec Report HI-2115004 6-54 Holtec Project 2119 1 4 3.5 3 2.5 2 1.5 1 0.5 0 A 3.5 3 2.5 2 1.5 0.5 0 0 TWW-Set2 Lk 0.1 1 10 Freqmuncy (Hz)100.1I I 10 100 Freqieucy (Hz)3.5 3 2.5 2 1.5 I 03 0 Z, 3.5 -3 2.5 2 1.5 0.5 0-0.1 0.1 1 10 Frequency (Hz)100 10 Fretqency (Hz)100 3.5 3 2.5 2 1.5 1 0.5 0 0.1 1 10 Frequency (Hlz)100 Figure 6.5.6 -Target and Generated Response Spectra in N-S Direction, Sets 1 to 5 Holtec Report 111-2115004 6-55 Holtec Project 2119 I Holtec Report HI-2115004 6-55 Holtec Project 2119 1 IResponse Spectra, Palisades SSE in N-S Direction, Average 3.5.. ..Target 3 Generated Average~IJ o I 2.5 I 1.5, 0.5 ....: 0.5 -\ ---- ----0.1 1 10 100 Frequency (Hz)Figure 6.5.7 -Target and Average of Generated Response Spectra in N-S Direction I PSD, Palisades SSE in N-S Direction, Average 1000 100 10~1 0.1 0.01 0.001 0.0001 Frequency (Hz)Figure 6.5.8 -Target and Average of Generated PSD in N-S Direction Holtc Rport1-1-2110046-5 Holec rojet 219 Holtec Report HI-2115004 6-56 Holtec Project 2119 i 02 02 0 Palisades SSE in VT Directon, Set 1 01 t 00-01-02 I a, I WMIUA~01 00 I' I~~'' P1 I 10 Time (sec)20 ,~00 AIU L-u;0 10 20 Time (sec)02 Palisades SSE in VT Direction, Set 4 0 1 00-02 0 10 20 Time (sec)I-02 0 10 Time (sec)20 02 Palisades SSE i- VT Direction-Set5-00-0 1 2 --------------
---0 2 Time (sec)Figure 6.5.9 -Generated Acceleration Time History in Vertical Direction, Sets 1 to 5 Holtec Report HI-21 15004 6-57 Holtec Project 2119 I Holtec Report HI-2115004 6-57 Holtec Project 2119 1 04 OA Sal .--Trget 0 .3 0.3 ..........
0.2 0.2 0.2-.1. --o.1 I. 0 0.1 1 10 100 0.1 10 100 Frequency (Hz) Frequency (H~zJ 04 .... Tre OA .... Tawge S- o 3 -Set4 0.3 0.3 0 j 0.2 0.2 -0.1 , 0.1 V .1 , 0 0 0.1 10 100 0.1 1 10 100 Frequency (Hz) FBequency (Hz)OA Target-- Set 6 0.3- _____-0.2 0.1 0.1 1 10 100 Frequency (Hz)Figure 6.5.10 -Target and Generated Response Spectra in Vertical Direction, Sets 1 to 5 Holtec Report HI-2115004 6-58 Holtec Project 2119 1 I Response Spectra, Palisades SSE in Vertical Direction, Average 0.4 0.3 0.2 0.1 0.1 0.1 1 10 Freqtency (Hz)100 Figure 6.5.11 -Target and Average of Generated Response Spectra in Vertical Direction I PSD, Palisades SSE in VT Direction, Average 100 10 1 0.1 0.01 0.1 1 10 100 Frequency (Hz)Figure 6.5.12 -Target and Average of Generated PSD in Vertical Direction Holtec Report 111-2115004 6-59 Holtec Project 2119 I Holtec Report HI-2115004 6-59 Holtec Project 2119 i XX X -X x x x > v1 x ,;y -MXXXXIXXXX)<
11-x x x x x x xx&#xfd; xX" x1IXxIIXxx XXXXXXX2XXXx xxxxIJIxxx~xxxxxxxxI Xx"x~xx xx~x xxxlxlx x xx xxx~xx x x"x xx xixx x Jxlxlx x x x x~xx x x x xxxxx~xx~xxlxxxx.Lxxxxxxx 7xxxxxxx x &#xfd;Lxxxxxxxxxxx Figure 6.6.1 -Limiting Interim Rack Storage Configuration during Installation Sequence Holtec Report HI-2 115004 6-60 iloltec Project 2119 I Holtec Report HI-2115004 6-60 Holtec Project 2119 1 CHAPTER 7: MECHANICAL ACCIDENTS CONSIDERATIONS
 
===7.1 Introduction===
The USNRC OT Position Paper (listed in Section 2.3 of this report) has been historically used to define mechanical accident events for fuel racks. The mechanical accidents pertain to a potential handling mishap that leads to an uncontrolled lowering of a load that is being carried over the fuel pool. Because the most common instance of load handling over the SFP involves the fuel assemblies, the mechanical accident scenarios are principally focused on evaluating the free fall of a fuel assembly (along with its handling tool) onto or into a fuel rack. In the case of Palisades, an accidental drop of the transfer canal gate during its handling also needs to be postulated as a credible event.7.2 Applicable Mechanical Accidents and Acceptance Criteria The OT Position Paper specifies that the design of a fuel rack must ensure its functional integrity under all credible load drop events. The drop events are intended to ensure that the mechanical strength of the rack is adequate to guarantee that the criticality safety characteristics of the rack module struck by the falling load will not be significantly decreased because of plastic deformation in the region of the rack facing enriched fuel. Based on the OT Position Paper, the following fuel drop scenarios have been considered in this safety analysis: 0 Shallow Drop Event 0 Deep Drop Event* Gate Drop Event* Rack Drop Event Holtec Report HI-2 115004 7-1 Holtec Project 2119 Holtec Report HI-2115004 7-1 Holtec Project 2119 Shallow Drop Event In the shallow drop event, the impactor (i.e., a fuel assembly plus its handling tool) is assumed to drop vertically and strike the top edge of the rack (see Figure 7.2.1). The storage cell in the rack subject to the impact is assumed not to contain a stored fuel assembly, and so the entire kinetic energy of impact must be absorbed by the rack itself. This assumption conservatively produces the maximum damage to the rack for this evaluation.
For this purpose, the fuel rack modules are equipped with a crush zone. The crush zone is defined as the region which is from the top of the rack to a depth which is 1.5 inches below the top of neutron absorber (Metamic).
The crush zone provides the sacrificial material that serves no criticality function.In order to ensure that the crush zone is adequate to withstand the impulse of an impactor, it is required that the plastic deformation of the rack cell wall resulting from a fuel assembly drop event must not extend beyond the crush zone. To conservatively estimate the crush damage to the cell wall, the rack is assumed to absorb the maximum kinetic energy generated by the impactor without any structural assist from the neutron absorber and the sheathing.
The structural factor of safety under the shallow drop event is defined as the ratio of the crush zone depth to the maximum depth of the damage.Deep Drop Event The deep drop event postulates that the impactor falls through an empty storage cell and impacts the rack baseplate.
The deep drop event can be classified into two scenarios, namely (1) a drop into an interior rack cell away from the support pedestals, and (2) a drop into a rack cell located above a support pedestal.In deep drop scenario 1, the impactor strikes the rack baseplate away from the support pedestal (see Figure 7.2.2), where the baseplate it is more flexible.
If the baseplate is pierced by the fuel assembly or deforms sufficiently to impact the liner then the liner may be damaged leading to possible leakage of pool water. An additional potential consequence of extensive baseplate deformation is that a portion of the fuel assembly active region is lowered outside the neutron Holtec Report HI-2115004 7-2 Holtec Project 2119 absorber equipped region of the rack cell. Conservatively, it is required that the rack module baseplate be sufficiently robust to prevent both piercing by the dropped fuel assembly and deformations large enough to cause secondary impact with the SFP liner or to cause the fuel assemblies in the impacted region to protrude excessively towards the liner leading to increase in the reactivity beyond that permitted for an accident event.For this purpose, the rack structure is required to be sufficiently stiff so that maximum lowering of the fuel assembly in the impacted cell and the cells surrounding it due to the bending or piercing of the baseplate must remain less than w and w/2, respectively, where w is the distance from the bottom surface of rack's baseplate to the top surface of liner plate. This condition of deformed module baseplate region is analyzed in Chapter 4 as a non-mechanistic event and shown to satisfy the applicable reactivity limit with considerable margin. In this structural evaluation, the amount of lowering of the impacted cell, d and the maximum lowering of the fuel in the surrounding cells (immediately adjacent to the impacted cell), e, is computed using LS-DYNA. The factor of safety is defined by the ratios w/d and w/(2e).The top and bottom fittings of the fuel assembly are simulated as rigid bodies to maximize the computed damage to the target.In deep drop scenario 2, the impactor strikes the rack baseplate directly atop a support pedestal (see Figure 7.2.3), which presents a hardened impact surface and results in a high impact load on the SFP floor and its stainless steel liner. The acceptance criterion for this drop scenario is that the accident must not result in local failure in the liner leading to a potential leakage of SFP water.Gate Drop Event The gate drop event postulates an accidental drop of the transfer canal gate onto the top edge of the rack. Similarly to the shallow drop event, the storage cell in the rack subject to the impact is assumed not to contain a stored fuel assembly, and so the entire kinetic energy of impact must be absorbed by the rack itself. This assumption conservatively maximizes the damage to the rack Holtec Report HI-2115004 7-3 Holtec Project 2119 for this evaluation.
The applicable structural criterion is identical to that described above for the fuel assembly shallow drop scenario.Rack Drop Event The rack drop event postulates an accidental vertical drop of the rack onto the top of the rack if the rack handling equipment is not designed, analyzed, fabricated, tested, and certified to NUREGs 0612 and 0554. Section 9.11.4.3, Item 8 of Palisades FSAR [5.1.7] states that the Facility Change FC-976 modified the main hoist of the Fuel Building Crane to increase the capacity to 110-tons, and to meet single failure criteria in accordance with NUREG-0612 and NUREG-0554 in 2003. Therefore, a rack drop analysis is not required due to the single failure proof crane at Palisades.
Stuck Fuel Event The structural integrity of rack cell walls under the uplift load caused by a postulated stuck fuel assembly is also evaluated.
The rack cell wall must be able to withstand this load without deforming the rack cell such that it does not adversely affect the integrity of the neutron absorber and thus affect the subcriticality of stored fuel array.Holtec Report HI-2 115004 7-4 Holtec Project 2119 Holtec Report HI-2115004 7-4 Holtec Project 2119 FURE1 ASSEM4BLY P2AVK Figure 7.2.1: Schematic of Shallow Drop Event Holtec Report HI-2 115004 7-5 Holtec Project 2119 Holtec Report HI-2115004 7-5 Holtec Project 2119 FUEL ASSEMBLV IMPACi REGION Figure 7.2.2: Schematic of Deep Drop Event Away From a Support Pedestal Holtec Report HI-2115004 7-6 Holtec Project 2119 FUEL ASSEMBLY RACK'IMPACT REGION Figure 7.2.3: Schematic of Deep Drop Event Above a Support Pedestal Holtec Report HI-2115004 7-7 Holtec Project 2119 7.3 Computer Code and Key Input Data The finite-element method is used to carry out the impact analysis for the postulated drop accidents.
LS-DYNA [7.3.1] is used to numerically simulate the impact events. LS-DYNA is a nonlinear, explicit, three-dimensional finite element code for solid and structural mechanics.
It was originally developed at Lawrence Livermore Laboratories and is ideally suited for study of short-time duration, highly nonlinear impact problems in solid mechanics.
LS-DYNA is commercially available and has been independently validated at Holtec following Holtec's QA procedures for commercial computer codes. LS-DYNA is currently supported and distributed by Livermore Software.
Each update is independently subject to QA validation at Holtec [7.3.2].This analysis methodology has been applied by Holtec in drop analyses for numerous wet storage projects that have been approved by the USNRC.The principal input data required to perform the LS-DYNA simulations is compiled in Tables 7.3.1 and 7.3.2.Holtec Report 111-2115004 7-8 Holtec Project 2119 Holtec Report HI-2115004 7-8 Holtec Project 2119 Table 7.3.1 KEY INPUT DATA PARAMETER VALUE Rack Cell Wall Thickness 0.090" Rack Module Height 161 1/8" Baseplate Thickness 1" Height of the Baseplate Above the Floor 12 5/8" Weight of Fuel Assembly & Handling Tool 2000 lb Fuel Drop Height Above Top of Racks 24" Weight of Gate 3000 lb Gate Drop Height Above Top of Racks 20" Width and Thickness of Gate 3' 5" x 5.5" Floor Liner Thickness 3/16" Holtec Report HI-2115004 7-9 Holtec Project 2119 Table 7.3.2 MATERIAL PROPERTIES Material Name Austenitic Stainless Zircaloy Precipitation Steel Hardened Stainless Steel Use Rack structure except Fuel assembly rod Rack male support male support pedestal cladding pedestal Material Type SA 240-304L Zircaloy SA 564-630 Density (pcf) 500 404 500 Elastic Modulus (psi) 2.787e+07 1.040e+07 2.877e+07 Stress (psi) N/A First Yield 2.270e+04 1.092e+05 Failure 6.805e+04 1.400e+05 Strain N/A Elastic 8.145e-04 3.796e-03 Failure 4.000e-01 1.400e-0 I Concrete Floor Slab Compressive Strength 3000 psi Holtec Report HI-21 15004 7-10 Holtec Project 2119 Holtec Report HI-2115004 7-10 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 7.4 Analysis 7.4.1 Mechanics of Underwater Dron Jioltec KepOrt HI-ill ,0U4 7-11 Holtec Project 2119 Holtec Report HI-2115004 7-11 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION 7.4.2 Numerical Simulation In the first step of the solution process, the velocity of the dropped object (impactor) is computed for the condition of underwater free fall in the manner of the formulation presented in the above subsection.
Table 7.4.1 contains the computed velocities for the various drop events.In the second step of the solution, an elasto-plastic finite-element model for each drop event is prepared with the LS-DYNA computer code, which has been QA-validated by Holtec. The model simulates the transient collision event with full consideration of plastic, large deformation, wave propagation, and elastic/plastic buckling modes.The fuel assembly model consists of four parts: a rigid bottom end fitting, an elastic beam representing the fuel rods, a lumped mass at the top end of the beam representing the handling tool, and a thin rigid shell that defines the enveloping size and shape of the fuel assembly.
The structurally weakest impact region is considered in performing the "shallow" and the "deep" drop analyses.
Shell elements are used to model the thin cell walls and weld connections.
The rack baseplate is modeled with thick shell elements and the rack support pedestal components are modeled with solid elements.
Other structural components, such as the liner and concrete slab, are also modeled with elasto-plastic shell and solid elements, as appropriate, in all drop events.Holtec Report HI-2115004 7-12 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION The physical properties of material types undergoing deformation in the postulated drop events are summarized in Table 7.3.2.The rack steel component materials are modeled using material model MAT_024 (i.e., MATPIECEWISELINEARPLASTICITY) in LS-DYNA. Material properties are based on engineering stress and strain at 150&deg;F and the ultimate failure strain limit is 0.4 in/in. The strain rate amplification curve applied to the base metal material is listed in Table 7.4.2. Throughout the simulation, the strain rate amplification factor for each base metal element is determined based on the instantaneous strain rate of the element. The time-dependent and element-dependent amplification factors are applied only to the stress values in the engineering stress-strain curve for the rack base metal material (SA240-304L).
Shallow Drop Event The LS-DYNA analysis results for the shallow drop are summarized in Table 7.4.3. Figure 7.4.1 shows the plastic strain and the extent of deformation in the crush zone resulting from the shallow drop event. It is observed that the plastic deformation
(>=0.01 in/in) of the cell wall is confined in the crush zone, and therefore, it is determined that the damage will not result in criticality concern or unacceptable consequences.
The factor of safety is provided in Table 7.4.3 and it is greater than 1.Deep Drop Events The LS-DYNA analysis results for the deep drop scenario I (through an internal cell away from the support pedestal) are summarized in Table 7.4.4. The LS-DYNA simulation shows that the deep drop does produce some deformation of the baseplate and localized severing of the baseplate/cell wall welds, but the baseplate is not pierced. The factors of safety for the lowering of the impacted cell and the surrounding cells are provided in Table 7.4.4 and they are significantly greater than 1. Figure 7.4.2 shows the extent of deformation of the baseplate from this deep drop event at the time the baseplate undergoes the maximum vertical deformation Holtec Report HI-2115004 7-13 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION (t=0.024 second). However, the fuel assembly support surface is lowered by less than 2.1 inches, which is much less than the distance between the baseplate and the pool liner. Therefore, the pool liner will not be contacted by the deformed baseplate.
The lowering of the baseplate has been considered in the criticality evaluation and is specifically addressed in Chapter 4 of this report.The LS-DYNA analysis results for the deep drop scenario 2 (through a cell above a support pedestal) are summarized in Table 7.4.5. It is found that the structural integrity of the support pedestal is not compromised by the impact. This deep drop event results in a bounding impact load as shown in Figure 7.4.3. The maximum plastic strain in the floor liner is 0.22%, as shown in Figure 7.4.4. The plastic strain is very small and this drop scenario meets the safety criteria.Gate Drop Event The vertical gate drop accident will involve at least four rack cells because of the dimensions of the gate; a gate drop accident hitting only a periphery cell wall would lead to immediate gate rotation because the gate width is more than four times the size of the rack cell. However, the impact energy of the gate is only about 1.17 times that of the fuel assembly in the shallow drop event. Therefore, it can be concluded that the gate drop accident is bounded by the shallow drop event in terms of the plastic strains sustained in the crush zone.Stuck Fuel Event The uplift force evaluation shows that the rack is able to withstand the vertical uplift force of 5,000 lbf. The maximum stress in the rack cell as a result of trying to pull the stuck fuel assembly out is only 1,500 psi which is well below the material yield strength.
Therefore, the fuel racks are adequate to withstand a 5,000 lbf uplift load due to a stuck fuel assembly.Holtec Report HI-2115004 7-14 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Table 7.4.1 IMPACT EVENT DATA Case Drop Height Above Impactor Impact Velocity Top of Rack (in) Weight (lb) Impactor Type (in/sec)Shallow Drop 24 2000 Fuel assembly 123.2 Deep Drop Away From Support Pedestal 24 2000 Fuel assembly 291.5 Deep Drop Above 24 2000 Fuel assembly 154.9 Support Pedestal Gate Drop 20 3000 Gate 108.6 Holtec Report HI-2 115004 7-15 Holtec Project 2119 Holtec Report HI-2115004 7-15 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Table 7.4.2 STRAIN RATE AMPLIFICATION CURVE FOR BASE METAL MATERIAL Strain Rate Amplification (in/in-sec)
Factor 0.0 1.0 5.0 1.202 10.0 1.244 22.0 1.346 10,000.0 1.346 Holtec Report HI-2 115004 7-16 Holtec Project 2119 Holtec Report HI-2115004 7-16 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Table 7.4.3 RESULTS FOR SHALLOW DROP Maximum Depth of Plastic Deformation
(>=0.01 in/in) 11.3672" measured from the rack top Maximum Allowable Crush Zone Depth 11.8125" Factor of Safety 1.04 Holtec Report HI-2 115004 7-17 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Table 7.4.4 RESULTS FOR DEEP DROP SCENARIO 1 (AWAY FROM SUPPORT PEDESTAL)Maximum Vertical Deformation of Baseplate in Impacted Cell 2.08" Allowable Vertical Deformation of Baseplate in Impacted Cell 12.625" Factor of Safety 6.07 Maximum Vertical Deformation of Baseplate Immediately Adjacent to Impacted Cell 1.65" Allowable Vertical Deformation of Baseplate Immediately Adjacent to Impacted Cell 6.3125" Factor of Safety 3.83 Holtec Report HI-2115004 7-18 Holtec Project 2119 SHADED AREAS CONTAIN HOLTEC PROPRIETARY INFORMATION Table 7.4.5 RESULTS FOR DEEP DROP SCENARIO 2 (ABOVE SUPPORT PEDESTAL)Maximum Impact Load 352,275 lbf Maximum stress in the liner 22,810 psi Holtec Report HI-21 15004 7-19 Holtec Project 2119 Holtec Report HI-2115004 7-19 Holtec Project 2119 SPENT FUEL ASSELUMLY SHALLOW DROP -REG TWW- "L GCOMMw of ESKeOw P~k Shahi Mkr0, atd ole mno.00400, at *bW Ifff Figure 7.4.1: Plastic Strain and Deformation from Shallow Drop Event (Note: Plastic strain in the red region exceeds 0.01 in/in)FMW gL*w4.1 006402 B ooa..w3 B 0.03 M90090.3,&.000643 50004-31 4b00.031 3.0000.03J ZO00O0.3 1M000,3 -&0000#W01 Holtec Report HI-2 115004 7-20 Holtec Project 2119 Holtec Report HI-2115004 7-20 Holtec Project 2119 LS-DYNA keyword deck by LS-PrePost Time = 0.024 Contours of Z-displacement min=-2.0777, at node# 113363 max=0.00398338, at node# 4428 Fringe Levels 3.983e-03-2.042e-01
-4.124e-01U
-6.205e-01_
-8.287e-01
-1 .037e+00-1 .245e*00J-1.453e+00J
-1.661e+00
-1.870e+00
-2.078e+00
_LY Figure 7.4.2: Baseplate Deformation from Deep Drop Event (Away from Support Pedestal)Holtec Report HI-2 115004 7-21 Holtec Project 2119 Holtec Report HI-2115004 7-21 Holtec Project 2119 N FUEL ASSELMBLY DEEP DROP SCENARIO 2 (REGION 1)0.35- ___ __0.3- ____ _0.25- _____0.2-_____
_0.15--0.1- __ _ __ _0.05-1A A Ai Contact Id AMa 4 0 0.006 0.01 0.016 0.02 0.026 min-0nm max,3.5276e+05 Figure 7.4.3: Floor Impact Force Time History from Deep Drop Event (Above Support Pedestal)Holtec Report HI-2 115004 7-22 Holtec Project 2119 Holtec Report HI-2115004 7-22 Holtec Project 2119 FUEL ASSELMBLY DEEP DROP SCENARIO 2 (RE Time -0.030001 Fringe Levels Contours of Effective Plastic Strain 2.210e.03 Ipt #2 and Ipt #31 mln-O, at elem# 150001 1.989e-03J max-0.0022090, at elem# 150030 1.76ge-03 1.647"03"i 1.326e-03 1.105e-03 8.83ge-04 6.629e-04
-4.419e-04 2.210e-04 0.0000+.00 y z Figure 7.4.4: Plastic Strain of the Floor Liner from Deep Drop Event (Above Support Pedestal)Holtec Report HJ-2 115004 7-23 Holtec Project 2119 Holtec Report HI-2115004 7-23 Holtec Project 2119
 
===7.5 Conclusion===
Several mechanical accidents are analyzed and found to produce localized structural damage in the impacted region well within the design limits for the racks. In the shallow drop event, it is observed that the plastic deformation
(>=0.01 in/in) of the cell wall is confined in the crush zone, and therefore, it is determined that the damage from the postulated shallow drop event will not result in criticality concern or unacceptable consequences.
Based on impact energy and geometry comparison, it is concluded that the gate drop event is bounded by the shallow drop event. The analysis of the deep drop event at a cell location selected to maximize baseplate deformation indicates that the baseplate is not pierced and that the maximum deflection of the baseplate does not lead to a secondary impact of the fuel assembly with the floor. The deep drop accident at the pedestal location shows that the rack and the pedestal remain structurally adequate and the impact transferred to the floor does not damage the pool liner which may precipitate seepage of pool's water. The rack uplift force evaluation shows that configuration of the Metamic is not compromised from the configurations analyzed in the criticality evaluations discussed in Chapter 4.Therefore, it is concluded that the rack modules are engineered to possess sufficient structural strength such that all acceptance criteria, conservatively specified to ensure continued safety performance of the modules under the postulated load drop events, are satisfied.
Holtec Report HI-2115004 7-24 Holtec Project 2119
 
===7.6 References===
[7.2.1] "Final Safety Analysis Report on the HI-STORM 100 system", Rev 9, Chapter 3, USNRC docket # 72-1014.[7.2.2] D. Ammerman, G. Bjorkman, "Strain-Based Acceptance Criteria for Section III of the ASME Boiler and Pressure Vessel Code", Proceedings of the 1 5 th International Symposium on the Packaging and Transportation of Radioactive Materials, PATRAM 2007, October 21-26, Miami, Florida, USA.[7.3.1] LS-DYNA 971, Livermore Software Technology.
[7.3.2] "LS-DYNA QA Validation Manual," Rev. 8, Holtec Report HI-961519.
[7.4.1 ] "Seismic Analysis of Safety Related Nuclear Structures and Commentary on Standard for Seismic Analysis of Related Nuclear Structures," ASCE Standard, ASCE 4-86, 1986.Holtec Report HI-2 115004 7-25 Holtec Project 2119 Holtec Report HI-2115004 7-25 Holtec Project 2119 CHAPTER 8: SAFETY CONSIDERATIONS FOR THE SFP WATER RETENTION BOUNDARY 8.1 Scope The fuel storage racks in the SFP are submerged in approximately 36.5 feet of borated water.The water mass in the SFP serves to extract decay heat from the stored fuel and delivers it to the plant's spent fuel cooling and clean-up system for ultimate rejection to the environment.
The tall column of water (over 21 feet) above the fuel also serves to provide radiation shielding.
Maintaining the fuel in the cooled state and providing radiation protection to the plant staff are among the principal functions of the pool water which bear upon the radiation safety of plant staff. To prevent inadvertent loss of water, the SFP has no penetrations except near their top water line. To ensure that an adequate inventory of the pool water exists in the Palisades SFP at all times, it is essential that the engineered barriers against uncontrolled loss of water from the pool remain effective under all operational conditions.
The barriers installed in the Palisades SFP to ensure water retention consist of the reinforced concrete structure and the pool liner. The former is designated as a safety significant load bearing structure that must meet the load combinations of the applicable ACI code [8.1.1] prescribed in the plant's FSAR. The latter -the pool liner made of seam welded sections of austenitic stainless steel -provides a non-structural barrier that is nevertheless important in keeping the corrosive pool water from affecting the reinforced concrete.
In this chapter, the necessary safety analyses to ensure that both water retention systems in the Palisades SFP will maintain their physical integrity under the loadings that act on them under all service conditions to which they are subjected during their design life.Holtec Report HI- 2115004 8-1 Holtec Project 2119 8.2 Reinforced Concrete Pool Structure The Palisades SFP is constructed of reinforced concrete and is oriented in the north-south direction in the auxiliary building.
The main pool floor is at elevation 611 feet with the tilt pit floors at elevation 610 feet. The SFP is supported by a series of walls which bear on the foundation mat at elevation 590 feet. The decontamination rooms, waste monitoring tanks and pumps, heating and ventilating pipeways are located in compartments below the fuel pool floor at elevation 590 feet. Thus, the pool structure extends upward from the mat at elevation 590 feet to operating floor elevation 649 feet. The pool walls also serve as support for adjacent floors in addition to their primary function to resist the hydrostatic pressure and fuel rack loads.The tilt pit water retention system is of a similar construction.
The width, depth and thickness of the reinforced concrete walls and pool slab of both pools are summarized in Table 8.2.1 herein.The applicable loads on the horizontal slabs of the SFP are: 1. Dead weight of the rack modules, D 2. Dead weight of the stored fuel, F 3. Dead weight of the water, W 4. Seismic inertia loading on the rack modules from the postulated earthquake events, E It is recognized that because the number of storage cells in the pool will not be changed as a result of the proposed operating license amendment, the structural safety of the pool slabs can be established by direct comparison of the loadings before and after the partial rerack operation.
In this respect, it is readily apparent that two of the four above mentioned loads, namely F and W, will remain unchanged, as will the load E from the portion of modules that is not being replaced.As Table 8.2.2 shows, load D and the load E are reduced after the rerack. Load E is obtained for the new freestanding racks from the Whole Pool Multiple-Rack analysis described in Chapter 6.The value of E for their counterpart racks (predecessor racks that are laterally restrained) is obtained from [8.2.2].Holtec Report HI- 2115004 8-2 Holtec Project 2119 Holtec Report HI- 2115004 8-2 Holtec Project 2119 Therefore, it follows that the load combinations applicable to the pool slab will either remain the same or decrease from the pre-rerack configuration of the pool. Hence the structural safety of the pool slab in both the main SFP and north tilt pit is confirmed.
In the case of the pool walls, the acting loads are: 1. Lateral pressure from the pool water, P 2. Seismic hydraulic pressure including sloshing effects, S 3. Mechanical force from seismic restraints, M It is readily apparent that the P and S loadings will remain unchanged by the reracking.
Because the seismic restraints are being removed, the mechanical load, M, from the new racks will vanish. Therefore, the aggregate loading on the pool walls will be reduced and-the margin of safety will be increased over the pre-rerack configuration.
Therefore, the structural capacity of the pool walls to withstand the loadings in the reracked SFP will remain undiminished.
Holtec Report 111-2115004 8-3 1-loltec Project 2119 Holtec Report Hl- 2115004 8-3 Holtec Project 2119 Table 8.2.1 KEY DIMENSIONS OF PALISADES STORAGE POOLS Main Spent Fuel Pool Length 38'-9" Width 14'-88" Height 38'-0" Slab Thickness 69-0" North Tilt Pit Length 21'-0" W idth 5 '-0 " Height 39'-0" Slab Thickness 5'-0" Holtec Report Hl- 2115004 8-4 Holtec Project 2119 Table 8.2.2 DEAD AND SEISMIC LOADS FROM REGION I RACK MODULES Item Current Configuration Post-Rerack Configuration (from [8.2.1]) (from [8.2.2])Supplier of Region I Racks NUS Holtec Number of Region I Racks in Main 6 6 SFP Sizes of Region I Racks in Main (4) 8x8, (1) 8x8-2x2, (4) 8x8, (1) 8x8-2x2, SFP (1) 8x8-2x4 (1) 8x8-2x4 Total Number of Region I Storage 372 372 Cells in Main SFP Number of Region I Racks in North 1 1 Tilt Pit Sizes of Region I Racks in North (1) 5x10 (1) 5x10 Tilt Pit Total Number of Region I Storage 50 50 Cells in North Tilt Pit Dead Weight of 8 x 8 Rack Module 116,480 110,800 (note 1)(w/ 64 fuel assemblies), lbf Total SSE & Dead Wt. Vertical 191,190 119,400 (note 2)Load Per Rack, lbf Notes: 1. Dry weight.2. Includes buoyancy effect of SFP water.Holtec Report Hl- 2115004 8-5 Holtee Project 2119 8.3 Pool Liner In this evaluation the potential failure modes of the liner are considered to ensure that a thru-wall leakage path in the liner will not develop due to mechanical loadings applied on it. The potential failure modes are: A. Tearing of the liner due to the shear load exerted on it through the bearing pad at rack pedestal locations.
B. Thru-wall fatigue failure from repetitive action of the shear (friction) forces on the liner under the cumulative effect of multiple earthquakes.
To perform the above evaluations, a structural model of the liner is prepared using the finite element code ANSYS as summarized below so as to maximize the local stress/strain in the liner.The ANSYS model, which is shown in Figure 8.3.1, consists of a 4' x 8' section of the liner and a 6" thick section of the concrete slab beneath the liner. The liner plate is constrained to the concrete floor along its perimeter edge to simulate the liner weld seam. Contact elements are used to simulate the interaction between the liner plate and the concrete slab over the interior region (i.e., away from the weld seams). The bottom surface of the concrete slab is fixed vertically, and it is laterally restrained along two sides.In addition to the hydrostatic pressure from the SFP water and the thermal stresses due to normal operating conditions, the liner is assumed to be subjected to a lateral force equal to the maximum shear loading obtained from the Whole Pool Multi-Rack simulations documented in Chapter 6.The shear force is assumed to be applied perpendicular to the welded liner seam (location of fixity) over the width of the bearing pad. The edge of the pad is assumed to be adjacent to the liner seam to maximize the local tensile stress.With the above conservative assumptions and the input data summarized in Table 8.3.1, the maximum shear stress in the liner is computed using classical stress analysis techniques.
Table Holtec Report Hl- 2115004 8-6 Holtec Project 2119 8.3.2 provides the maximum computed stress and its comparison with the allowable shear stress for the liner material.
The maximum alternating stress intensity in the liner is also compared to the endurance strength of the liner material in Table 8.3.2. A cyclic stress amplitude below the endurance limit of the material (i.e., allowable alternating stress intensity at one million cycles)provides the assurance that the SFP liner can withstand the cumulative effects of 1 SSE and 20 OBE events.Holtec Report HI- 21i5004 8-7 Holtec Project 2119 Holtec Report HI- 2115004 8-7 Holtec Project 2119 Table 8.3.1 KEY INPUT DATA FOR SFP LINER EVALUATION Item Value Liner thickness, in 0.1875 Liner plate dimensions, in 48 x 96 Width of bearing pad, in 12 Hydrostatic pressure on SFP liner, psi 17.3 (note 1)Bounding normal operating temperature, OF 150 Maximum shear load on SFP liner from <35,000 WPMR analysis, lbf Notes: 1) Conservatively based on 40 feet of water.Holtec Report 111-2115004 8-8 Holtec Project 2119 Holtec Report Hl- 2115004 8-8 Holtec Proj&t 2119 Table 8.3.2 RESULTS OF SFP LINER EVALUATION Item Value Maximum computed shear stress in the liner, psi 7,991 Allowable shear stress for liner material at 150'F, psi 12,076 Factor of safety against tearing 1.51 Maximum computed alternating stress intensity, psi 8,000 Number of stress cycles associated with 1 SSE and 20 7,140 OBE events Maximum allowable alternating stress intensity at 1 28,200 million stress cycles (per Table 1-9.2.2 of [8.3.1]), psi Cumulative damage factor 7,140 / 1,000,000
= 0.00714 Holtec Report HI- 2115004 8-9 Holtec Project 2119
 
===8.4 References===
[8.1.1] ACI 318-71, "Building Code Requirements for Reinforced Concrete", American Concrete Institute, 1971.[8.2.1] K.R. Rao, "Structural Analysis of the Palisades Spent Fuel Storage Pool for Partial Rerack" Westinghouse Electric Corporation, April 1986.[8.2.2] Holtec Report HI-2115014, "Structural/Seismic Analysis for Palisades Region I Spent Fuel Racks", Revision 0.[8.3.1] ASME Boiler & Pressure Vessel Code, Section III, Division 1 -Appendices, 1998 Edition.Holtec Report HI- 2115004 8-10 Holtec Project 2119 Holtec Report HI- 2115004 8-10 Holtec Project 2119 ELEMENTS TYPE NUM Liner Integrity FEB 8 2012 11:10:53 FIGURE 8.3.1: FINITE ELEMENT MODEL OF SFP LINER SECTION Holtec Report HI- 2115004 8-11 Holtec Project 2119 Holtec Report Hl- 2115004 8-11 Holtec Project 2119 CHAPTER 9: RADIOLOGICAL EVALUATION
 
===9.1 Introduction===
This chapter addresses the radiological evaluations for the partial re-racking operation of the Palisades spent fuel pool. Previous analyses describe a fuel handling accident (FHA) in References
[9.1.1, 9.1.2]. The results given in Reference
[9.1.1] are bounding values that cover a FHA in either the fuel handling building (FHB) or the containment.
The FHA analyses in the above mentioned references are still valid and applicable.
Additional radiological analyses for this partial re-racking project are considered unnecessary.
 
===9.2 Methodology===
The basic methodology of this chapter is to show that the spent fuel pool re-racking project in 2013 does not affect the radiological evaluations performed previously.
9.3 Acceptance Criteria The maximum permissible doses for the postulated fuel handling accident are summarized in Table 9.3.1.Holtec Report HI-2115004 9-1 Holtec Project 2119 TABLE 9.3.1 FUEL HANDLING ACCIDENT ACCEPTANCE CRITERIA [9.3.1, 9.3.2]EAB (a) LPZ (a) CR (b)Dose Contribution 2-hr 30 days 30 days (rem TEDE) (rem TEDE) (rem TEDE)Acceptance Criteria 6.3 6.3 5 (a) The acceptance criteria for the offsite doses are given in RG 1.183 [Reference 9.3.1], which are based upon 1OCFR Part 50 Section 67.(b) The acceptance criteria for the control room doses are given in 1OCFR Part 50 Section 67.Holtec Report HI-2 115004 9-2 Holtec Project 2119 Holtec Report HI-2115004 9-2 Holt6c Project 2119 9.4 Assumptions and Operating Parameters The major assumptions along with the operating parameters, used in the radiological evaluations, can be found in References
[9.1.1, 9.1.2].9.5 Analysis The doses from the fuel handling accident are calculated and documented for the currently installed racks in References
[9.1.1, 9.1.2], respectively.
The factors affecting the calculation, such as depth of the pool, the exposure of the fuel assembly considered when the accident occurs, the cooling time of the assembly, etc. have not changed. Consequently, the postulated doses from the fuel handling accident remain identical to the values determined in the earlier calculation.
It should also be noted that core input parameters along with the fuel descriptions are not altered as a result of the partial re-rack of the wet storage system at Palisades.
The total fuel capacity also remains unchanged.
The dose rate at the pool surface, as reported in Section 9.11 in Reference
[9.1.1] also remains unchanged.
The pool surface dose rate is determined by the, fuel being unloaded from the core in refueling and this is the same as that experienced before the implementation of this re-racking project. The dose at the spent fuel pool is dependent upon the operating specific power in the core and the time after shutdown when the spent fuel is moved. As previously mentioned these parameters have not changed and hence the dose rate at the pool surface has not changed either.9.6 Conclusions In light of the arguments presented in Section 9.5, the radiological analyses reported in references
[9.1.1] and [9.1.2] are still valid and applicable.
The dose rates meet the acceptance criteria given in Section 9.3 as well. Additional radiological analyses for this partial re-racking are considered unnecessary.
Holtec Report HI-2115004 9-3 Holtec Project 2119
 
===9.7 References===
[9.1.1] Palisades Plant Final Safety Analysis Report Rev. 29[9.1.2] NAI- 1149-016 Rev. 1, Palisades Design Basis Fuel Handling Accident AST Radiological Analysis[9.3.1] US NRC Regulatory Guide 1.183, Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors July 2000.[9.3.2] 10 CFR 50.67, "Accident Source Term." Holtec Report 111-2115004 9-4 Holtec Project 2119 Holtec Report HI-2115004 9-4 Holtec Project 2119 CHAPTER 10: INSTALLATION 10.1 Introduction The installation phase of the fuel storage rack project involves removal of the existing Region 1 storage racks and installation of the new Region I racks in the SFP. All installation work will be performed in compliance with NUREG-0612 (Control of Heavy Loads at Nuclear Power Plants, 1980), and applicable Holtec and site procedures.
Crane and fuel bridge operators are trained in the operation of overhead cranes per the requirements of ANSI/ASME B30.2, and the plant's specific training program. Consistent with the installer's past practices, a videotape aided or equivalent training session is presented to the installation team, all of whom are required to successfully complete a written examination prior to the commencement of work. Fuel handling bridge operations are performed by site personnel, who are trained in accordance with site procedures.
Rack lifting devices are required for the handling of new racks and existing racks. The lifting devices are designed to engage and disengage on lift points at the bottom of the racks. The lifting devices comply with the provisions of ANSI N14.6-1978 and NUREG-0612, including compliance with the design stress criteria, load testing at a multiplier of maximum working load, and nondestructive examination of critical welds.A surveillance and inspection program shall be maintained as part of the installation of the racks.A set of inspection points, which have been proven to eliminate any incidence of rework or erroneous installation in previous rack projects, is implemented by the installer.
Holtec procedures will be used in conjunction with the site procedures to cover the scope of activities for the rack removal and installation effort. Similar procedures have been utilized and successfully implemented by Holtec on previous rerack projects.
These procedures are written to include ALARA (As Low As Reasonably Achievable) practices and provide requirements to Holt6c Report HI-2115004 10-1 Holtec Project 2119 assure equipment, personnel, and plant safety. These procedures are reviewed and approved in accordance with site administrative procedures prior to use. The following is a list of the Holtec procedures, used in addition to the site procedures to implement the installation phase of the project.A. Installation/Removal and Handling Procedure:
This procedure provides direction for the installation, removal, and handling of the new and existing storage rack modules in the spent fuel pool. This procedure delineates the steps necessary to receive the new racks on site, the proper method for unloading and uprighting the racks, staging the racks prior to installation, removal and packaging of existing racks, and installation of the new racks. The procedure provides for the installation of the new racks, their height and level adjustments of the rack pedestals and verification of the as-built field configuration to ensure compliance with design documents.
B. Receipt Inspection Procedure:
This procedure delineates the steps necessary to perform a thorough receipt inspection of a new rack module after its arrival on site. The receipt inspection includes dimensional measurements, cleanliness inspection, visual weld examination, and verticality measurements.
C. Cleaning Procedure:
This procedure provides for the cleaning of a new rack module, if required.
The modules are to meet the requirements of ANSI N45.2. 1, Level B, prior to placement in the SFP. Methods and limitations on cleaning materials to be utilized are provided.D. Pre- and Post-Installation Drag Test Procedure:
These two procedures stipulate the requirements for performing a functional test on a new rack module prior to and following installation.
The procedures provide direction for inserting and Holtec Report HI-2115004 10-2 Holtec Project 2119 withdrawing an insertion gage into designated cell locations, and establish an acceptance criterion in terms of maximum drag force. Pre-installation drag testing may be performed either at the fabrication facility or at the site.E. ALARA Procedure:
Consistent with Holtec's ALARA Program, this procedure provides guidance to minimize the total man-rem received during the rack installation project, by accounting for time, distance, and shielding.
This procedure will be used in conjunction with the site ALARA program.F. Underwater Welding Procedure:
Underwater welding procedures are used for reinstalling previously cut and removed SFP obstructions and other items as may be identified during installation of the new storage racks.The procedures contain appropriate qualification records documenting relevant variables, parameters, and limiting conditions.
The weld procedure is qualified in accordance with ASME Section XI, or may be qualified to an alternate code accepted by both the owner and Holtec.10.2 Rack Arrangement The fuel storage rack project will not change the rack arrangement in the SFP. Seven existing Region 1 racks will be replaced by seven new Region 1 racks that have the same array sizes, storage capacities, cell pitch and approximate dimensions (length, width and height).10.3 Rack Interferences The new Region 1 racks will have the same approximate dimensions (length, width and height)as the existing Region I racks. The current south-wall seismic restrains structure will be removed. There should be no new interferences following rack installation.
Holtec Report HI-2115004 10-3 Holtec Project 2119 10.4 Removal of Existing Racks and Installation of New Racks Because of the current fuel assembly inventory in the SFP it is not possible to empty and remove all existing Region 1 racks at one time. Therefore, it will be necessary to empty and remove individual existing racks and replace them with new racks on at a time. As new racks are installed stored fuel assemblies will be shuffled from the existing racks into the new racks. This is implemented procedurally as described in Item A of Section 10.1.For existing rack removal from the SFP, the racks will be cleaned via pressure washing and surveyed by Health Physics prior to removal from the SFP. All existing rack handling shall be completed by the single-failure-proof fuel building crane. The removed racks shall be moved to a designated area for packaging and preparation for shipment to an approved disposal facility.Installation of the new racks, supplied by Holtec, involves the following activities.
The racks are delivered in the horizontal position.
A new rack module is removed from the shipping trailer using a suitably rated crane, while maintaining the horizontal configuration.
The rack is placed on the up-ender and secured. Using two independent overhead hooks, or a single overhead hook and a spreader beam, the module is up-righted into a vertical position.The new rack lifting device is engaged in the lift points at the bottom of the rack. The rack is then transported to a pre-leveled surface where, after leveling the rack, the appropriate quality control receipt inspection is performed (see Section 10.1, Items B and D).The spent fuel pool floor is inspected and any debris that may inhibit the installation of the racks is removed. As part of this inspection any liner seams or other floor projections that lie beneath intended bearing pad locations are identified and any shimming or slotting of bearing pads is performed in accordance with governing design drawings and analyses.
The bearing pads are then installed.
The new rack module is lifted with the single-failure-proof fuel building crane and transported along the pre-established safe load path. The rack module is carefully lowered into the SFP.Holtec Report HI-2115004 10-4 Holtec Project 2119 Elevation readings are taken to confirm that the module is level and the pedestal heights are adjusted as necessary to achieve level. In addition, rack-to-wall and rack-to-rack off-set distances (gaps) are also measured.
Adjustments are made as necessary to ensure compliance with design documents.
The lifting device is then disengaged and removed from the spent fuel pool under Health Physics direction.
As directed by procedure, post-installation free path verification of individual cells is performed using an inspection gage (see Section 10.1, Item D).All of the rack removal and installation activities in the SFP floor area will take place within a defined foreign material exclusion zone. At the completion of all activities, the SFP floor area shall be confirmed to be at the same level of cleanliness and condition that existed prior the start of installing the new racks.10.5 Safety, Health Physics, and ALARA Methods 10.5.1 Safety During the installation phase of the fuel storage rack project, personnel safety is of paramount importance.
All work shall be carried out in compliance with applicable approved procedures.
10.5.2 Health Physics Health Physics is carried out per the requirements of the site radiation protection program.10.5.3 ALARA The key factors in maintaining project dose As Low As Reasonably Achievable (ALARA) are time, distance, and shielding.
These factors are addressed by utilizing many mechanisms with respect to project planning and execution.
Holtec Report HI-2115004 10-5 Holtec Project 2119 Time Each member of the project team is trained and provided appropriate education and understanding of critical evolutions.
Additionally, daily pre-job briefings are employed to acquaint each team member with the scope of work to be performed and the proper means of executing such tasks. Such pre-planning devices reduce worker time within the radiological controlled area and, therefore, project dose.Distance Remote tooling such as lift fixtures, pneumatic grippers, a support leveling device and a lift rod disengagement device have been developed to execute numerous activities from the SFP surface, where dose rates are relatively low.Shielding During the course of the fuel storage rack project, primary shielding is provided by the water in the spent fuel pool. The amount of water between an individual at the surface and an irradiated fuel assembly is an essential shield that reduces dose. Additionally, other shielding may be employed to mitigate dose when work is performed around high dose rate sources. If necessary, additional shielding may be utilized to meet ALARA principles.
As materials are being removed from the SFP, particular attention will be paid to controlling the removal of any irradiated particles from the SFP (e.g., pressure washing and Health Physics surveys of racks being removed from the SFP, as described in Section 10.4).10.6 Radwaste Material Control Radioactive waste generated from the rack installation will be controlled in accordance with established site procedures.
Holtec Report 111-2115004 10-6 Holtec Project 2119 Holtec Report HI-2115004 10-6 Holtec Project 2119}}

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