ML25216A055

Enclosure 2: 11x11 RAJ-II Letter Authorization Request and Technical Basis - Non-Proprietary Information

ML25216A055
Person / Time
Site:	07109309
Issue date:	08/04/2025
From:	Global Nuclear Fuel
To:	Office of Nuclear Material Safety and Safeguards
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ML25216A052	List: ML25216A056
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M250198
Download: ML25216A055 (1)

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ENCLOSURE 2 M250198 11x11 RAJ-II Letter Authorization Request and Technical Basis Non-Proprietary Information IMPORTANT NOTICE This is a non-proprietary version of M250198 Enclosure 1, which has the proprietary information removed. Portions of the document that have been removed are indicated by white space with an open and closed bracket as shown here (( )).

M250198 Non-Proprietary Information Page 1 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table of Contents 1.0 General Information........................................................................................................11 1.1 Introduction................................................................................................................... 11 1.2 Package Description...................................................................................................... 11 1.2.1 Packaging...................................................................................................................12 1.2.2 Contents.....................................................................................................................12 1.2.3 Special Requirements for Plutonium.........................................................................13 1.2.4 Operational Features..................................................................................................13 1.3 References..................................................................................................................... 13 1.4 GNF 11x11 LUA Design Description.......................................................................... 13 1.4.1 GNF 11x11 Fuel Product Description.......................................................................14 1.4.1.1 Parameters Within CoC Range......................................................................... 14 1.4.1.2 Parameters Unique to GNF 11x11 LUAs......................................................... 14 1.4.2 Conclusion.................................................................................................................18 2.0 Structural evaluation.......................................................................................................19 2.1 Description of the Structural Design............................................................................. 19 2.1.1 Discussion..................................................................................................................19 2.1.2 Design Criteria...........................................................................................................20 2.1.3 Weights and Centers of Gravity.................................................................................20 2.1.4 Identification of Codes and Standards for Package Design.......................................20 2.2 Materials....................................................................................................................... 20 2.3 Fabrication and Examination........................................................................................ 20 2.4 General Requirements for All Packages....................................................................... 20 2.5 Lifting and Tie-Down Standards for All Packages....................................................... 20 2.6 Normal Conditions of Transport................................................................................... 21 2.6.1 Heat............................................................................................................................21 2.6.1.1 Summary of Pressures and Temperatures......................................................... 21 2.6.1.2 Differential Thermal Expansion....................................................................... 21 2.6.1.3 Stress Calculations............................................................................................ 23

M250198 Non-Proprietary Information Page 2 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.6.1.4 Comparison with Allowable Stresses............................................................... 23 2.6.2 Cold............................................................................................................................23 2.6.3 Reduced External Pressure........................................................................................23 2.6.4 Increased External Pressure.......................................................................................23 2.6.5 Vibration....................................................................................................................24 2.6.6 Water Spray...............................................................................................................24 2.6.7 Free Drop...................................................................................................................24 2.6.8 Corner Drop...............................................................................................................24 2.6.9 Compression..............................................................................................................24 2.6.10 Penetration.................................................................................................................24 2.7 Hypothetical Accident Conditions................................................................................ 24 2.7.1 Free Drop...................................................................................................................24 2.7.1.1 End Drop........................................................................................................... 26 2.7.1.2 Side Drop.......................................................................................................... 26 2.7.1.3 Corner Drop...................................................................................................... 26 2.7.1.4 Oblique Drops................................................................................................... 26 2.7.1.5 Horizontal Drop................................................................................................ 26 2.7.1.6 Summary of Results.......................................................................................... 27 2.7.2 Crush..........................................................................................................................27 2.7.3 Puncture.....................................................................................................................27 2.7.4 Thermal......................................................................................................................27 2.7.5 Immersion - Fissile Material.....................................................................................27 2.7.6 Immersion - All Packages.........................................................................................27 2.7.7 Deep Water Immersion Test (for Type B Packages Containing More than 105 A2).27 2.7.8 Summary of Damage.................................................................................................28 2.8 Accident Conditions for Air Transport of Plutonium................................................... 28 2.9 Accident Conditions for Fissile Material Packages for Air Transport......................... 28 2.10 Special Form................................................................................................................. 28 2.11 Fuel Rods...................................................................................................................... 28

M250198 Non-Proprietary Information Page 3 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.12 Appendix....................................................................................................................... 28 2.12.1 References..................................................................................................................28 2.12.2 Certification by Analysis...........................................................................................28 2.12.2.1 RAJ-II Container Model................................................................................... 29 2.12.2.2 Detailed 11x11 Fuel Bundle Models................................................................ 38 3.0 Thermal Evaluation.........................................................................................................50 3.1 Description of Thermal Design..................................................................................... 50 3.1.1 Design Features..........................................................................................................50 3.1.2 Contents Decay Heat................................................................................................50 3.1.3 Summary Tables of Temperatures.............................................................................50 3.1.4 Summary Tables of Maximum Pressures..................................................................50 3.2 Material Properties and Component Specifications...................................................... 51 3.2.1 Material Properties.....................................................................................................51 3.2.2 Component Specifications.........................................................................................51 3.3 Thermal Evaluation Under Normal Conditions of Transport....................................... 51 3.3.1 Heat and Cold............................................................................................................51 3.3.2 Maximum Normal Operating Pressure......................................................................51 3.4 Thermal Evaluation Under Hypothetical Accident Conditions.................................... 51 3.4.1 Initial Conditions.......................................................................................................51 3.4.2 Fire Test Conditions...................................................................................................51 3.4.3 Maximum Temperatures and Pressure.......................................................................52 3.4.4 Maximum Thermal Stress..........................................................................................52 3.4.5 Accident Conditions for Fissile Material Packages for Air Transport......................53 3.5 Appendix....................................................................................................................... 53 3.5.1 References..................................................................................................................53 4.0 Containment.....................................................................................................................54 4.1 Description of the Containment System....................................................................... 54 4.2 Containment Under Normal Conditions of Transport.................................................. 54 4.3 Containment Under Hypothetical Accident Conditions............................................... 54

M250198 Non-Proprietary Information Page 4 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 4.4 Leakage Rate Tests for Type B Packages..................................................................... 54 4.5 References..................................................................................................................... 54 5.0 Shielding Evaluation........................................................................................................55 5.1 References..................................................................................................................... 55 6.0 Criticality Evaluation......................................................................................................56 6.1 Description of Criticality Design.................................................................................. 56 6.1.1 Design Features..........................................................................................................57 6.1.2 Summary Table of Criticality Evaluation..................................................................57 6.1.3 Criticality Safety Index..............................................................................................58 6.2 Fissile Material Contents.............................................................................................. 59 6.3 General Considerations................................................................................................. 59 6.3.1 Model Configuration..................................................................................................59 6.3.2 Material Properties.....................................................................................................60 6.3.3 Computer Codes and Cross-Section Libraries...........................................................60 6.3.4 Demonstration of Maximum Reactivity....................................................................61 6.3.4.1 Fuel Assembly Orientation Study..................................................................... 63 6.3.4.2 Fuel Assembly Gadolinia Rod Study (2N=9)................................................... 63 6.3.4.3 Fuel Assembly Channel Study.......................................................................... 63 6.3.4.4 Polyethylene Mass Study.................................................................................. 63 6.3.4.5 Fuel Rod Pitch Sensitivity Study (2N=9)......................................................... 63 6.3.4.6 Fuel Pellet Diameter Sensitivity Study (2N=9)................................................ 65 6.3.4.7 Fuel Rod Clad Thickness Sensitivity Study (2N=9)......................................... 67 6.3.4.8 Worst Case Parameter Fuel Designs................................................................. 68 6.3.4.9 Part Length Fuel Rod Study.............................................................................. 69 6.3.4.10 Moderator Density Study.................................................................................. 69 6.3.4.11 Material Distribution Reactivity Study (2N=9)................................................ 71 6.3.4.12 Inner Container Partial Flooding Study............................................................ 74 6.3.4.13 RAJ-II Package Spacing Study......................................................................... 74 6.3.4.14 Other Considerations........................................................................................ 74

M250198 Non-Proprietary Information Page 5 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.4 Single Package Evaluation............................................................................................ 74 6.5 Evaluation of Package Arrays Under NCT................................................................... 74 6.6 Package Arrays Under HAC (2N=9)............................................................................ 75 6.6.1 Configuration.............................................................................................................75 6.6.2 Results........................................................................................................................75 6.6.2.1 Pu-239 Effect on Reactivity for the RAJ-II Package Array HAC.................... 77 6.7 Fuel Rod Transportation in the RAJ-II......................................................................... 78 6.8 Fissile Material Packages for Air Transport................................................................. 78 6.9 Conclusion.................................................................................................................... 78 6.10 Benchmark Evaluations................................................................................................ 78 6.10.1 SCALE 4.4a and GEMER.........................................................................................78 6.10.2 KENO-VI...................................................................................................................78 6.11 Appendix....................................................................................................................... 78 6.12 References..................................................................................................................... 78 7.0 Package Operations.........................................................................................................80 8.0 Acceptance Tests and Maintenance Program...............................................................81

M250198 Non-Proprietary Information Page 6 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis List of Tables Table 1 Comparison of Fuel Assembly Parameters for the Approved GNF 10x10 Designs and the GNF 11x11 LUA...............................................................................17 Table 2 Thermal Contraction at -40°C.....................................................................................21 Table 2 GNF 11x11 Thermal Expansion at 800°C..................................................................22 Table 2 GNF 11x11 Additive Pellet Thermal Strains..............................................................23 Table 2 Limiting HAC Drop Orientations...............................................................................25 Table 2 LS-DYNA RAJ-II Component Masses per Simulation..............................................32 Table 2 GNF 11x11 Fuel Cladding Strain Results...................................................................43 Table 2 Expansion at First Time-Step......................................................................................47 Table 2 Expansion at Second Time-Step.................................................................................48 Table 2 Expansion at Third Time-Step....................................................................................49 Table 2 GNF4 11x11 Overall Lattice Expansion...................................................................49 Table 6 LUA Parameters Beyond the RAJ-II SAR.................................................................57 Table 6 Criticality Evaluation Summary for GNF 11x11 LUAs.............................................58 Table 6 Nominal vs. Worst Case Fuel Parameters for the GNF 11x11 LUA.........................58 Table 6 Summary of Criticality Safety Index for GNF 11x11 LUAs.....................................58 Table 6 Limiting HAC Model Parameters for RAJ-II Package Array Containing the Bounding Fuel Assembly.......................................................................................62 Table 6 Fuel Rod Pitch at Optimal Moderation (2N=9)..........................................................64 Table 6 Fuel Pellet Outer Diameter Sensitivity Study Results (2N=9)...................................66 Table 6 Fuel Cladding Thickness Sensitivity Study Results (2N=9)......................................67 Table 6 Outer Container Moderator Density Sensitivity Study Results (2N=9).....................69 Table 6 Inner Container Moderator Density Sensitivity Study Results (2N=9)....................70 Table 6 RAJ-II Inner Container Thermal Insulator Region (2N=9)......................................72 Table 6 RAJ-II PCF Thickness Study Results (2N=9)..........................................................72 Table 6 NCT, HAC Single Package Versus HAC Package Array (2N=9)...........................74 Table 6 Optimal RAJ-II HAC Array - Inner Container Moderator Study............................75 Table 6 Optimal RAJ-II HAC Array - Outer Container Moderator Study...........................76

M250198 Non-Proprietary Information Page 7 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis List of Figures Figure 1 GNF 11x11 Lattice Layout by Axial Zone................................................................15 Figure 1 Fuel Bundle Assembly Schematics, GNF3 (10x10) and GNF 11x11.......................16 Figure 2 RAJ-II LS-DYNA Finite Element Model Assemblies..............................................29 Figure 2 RAJ-II LS-DYNA Finite Element Component Models............................................30 Figure 2 RAJ-II LS-DYNA Full Model Transverse Cross Section.........................................31 Figure 2 End Drop Inner Container Decelerations for CTU-1J...............................................33 Figure 2 Top Drop Inner Container Decelerations for CTU-2J...............................................34 Figure 2 Top Drop Fuel Bundle Decelerations for CTU-2J.....................................................34 Figure 2 Corner Drop Fuel Bundle Decelerations for CTU-1J................................................35 Figure 2 11x11 End Drop Fuel ATH.......................................................................................36 Figure 2 11x11 Side Drop Fuel ATH.......................................................................................36 Figure 2 11x11 Corner Drop Fuel ATH, -40°C.....................................................................37 Figure 2 11x11 Corner Drop Fuel ATH, 77°C......................................................................37 Figure 2 GNF2 10x10 End Drop Fuel ATH, -40°C...............................................................38 Figure 2 Cladding Strain Vertical End Drop Model..............................................................40 Figure 2 Cladding Strain Horizontal Side Drop Model.........................................................41 Figure 2 Cladding Strain Corner Drop Model.......................................................................42 Figure 2 Overall Maximum HAC Cladding Strain - Corner Drop, -40°C............................43 Figure 2 Rod Pitch Change....................................................................................................44 Figure 2 Lattice Expansion Model Setup...............................................................................45 Figure 2 First Time-Step Post-Drop Position Plot.................................................................47 Figure 2 Second Time-Step Post-Drop Position Plot.............................................................48 Figure 2 Third Time-Step Post-Drop Position Plot................................................................49 Figure 6 RAJ-II Cross-Sectional HAC Model without Gadolinia Rods.................................60 Figure 6 RAJ-II GNF 11x11 LUA Fuel Rod Pitch Sensitivity Study.....................................65 Figure 6 RAJ-II GNF 11x11 LUA Fuel Pellet Outer Diameter Sensitivity Study..................66 Figure 6 RAJ-II GNF 11x11 LUA Fuel Cladding Thickness Sensitivity Study.....................68

M250198 Non-Proprietary Information Page 8 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Figure 6 RAJ-II GNF 11x11 LUA Outer Container Moderator Density Sensitivity Study............................................................................................................................70 Figure 6 RAJ-II GNF 11x11 LUA Inner Container Moderator Density Sensitivity Study............................................................................................................................71 Figure 6 RAJ-II GNF 11x11 LUA PCF Thickness Sensitivity Study Results........................73 Figure 6 RAJ-II Optimal HAC Inner Container Moderator Density Sensitivity Study............................................................................................................................76 Figure 6 RAJ-II Optimal HAC Outer Container Moderator Density Sensitivity Study............................................................................................................................77

M250198 Non-Proprietary Information Page 9 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis GLOSSARY OF TERMS AND ACRONYMS Acronym Definition ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATH Acceleration Time History BPVC Boiler and Pressure Vessel Code BWR Boiling Water Reactor CFR Code of Federal Regulations CoC Certificate of Compliance CSA Criticality Safety Analysis CSI Criticality Safety Index CTU Certification Test Unit Gd2O3-UO2 Gadolinia-Urania GNF Global Nuclear Fuel - Americas, LLC GNF-J Global Nuclear Fuel - Japan HAC Hypothetical Accident Conditions IC Inner Container ID Inner Diameter keff Neutron Multiplication Factor LEP Lower End Plug LTP Lower Tie Plate LUA Lead Use Assembly NCT Normal Conditions of Transport NRC Nuclear Regulatory Commission OC Outer Container OD Outer Diameter PCF Polyethylene Cushioning Foam PLR Part Length Rod

M250198 Non-Proprietary Information Page 10 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Acronym Definition SAR Safety Analysis Report U-235 Uranium-235 UO2 Uranium Dioxide UE Uniform Elongation USL Upper Subcritical Limit UTP Upper Tie Plate wt%

Weight Percent

M250198 Non-Proprietary Information Page 11 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 1.0 GENERAL INFORMATION The purpose of this letter authorization request is to seek Nuclear Regulatory Commission (NRC) approval to ship a new 11x11 fuel bundle design from Global Nuclear Fuel - Americas, LLC (GNF). As part of the new product introduction program, limited quantities of unirradiated GNF 11x11 Lead Use Assemblies (LUAs) are shipped to plant sites starting in the year 2026. The evaluations presented in this letter authorization request provide the safety basis for a change in the contents for shipment in the RAJ-II and evaluates the change relative to the approved safety evaluations documented in the GNF RAJ-II Safety Analysis Report (SAR), Docket Number 71-9309, Revision 11, as amended (Reference 1-1).

The sections from the SAR that remain applicable to GNF 11x11 LUAs are referenced in this letter authorization request. GNF 11x11 LUA specific evaluations are discussed in detail. For completeness, Section 1.4 provides a detailed description of the GNF 11x11 LUA design to aid the NRC in the review. The design description is provided in the context of comparing the GNF 11x11 LUA design to an example of the currently approved contents as described in the RAJ-II Certificate of Compliance (CoC) Number 9309, Revision 14 (Reference 1-2).

The NRC approved the GNF quality assurance program that is described in NEDO-11209-A, Revision 17 (Reference 1-3) which specifically complies with 10 Code of Federal Regulations (CFR) Part 50 (10 CFR 50) Appendix B requirements and is adopted to meet the requirements of 10 CFR 71, Subpart H for transportation of radioactive material.

1.1 Introduction The model RAJ-II package (identification number USA/9309/B(U)F-96) is approved for shipments of unirradiated Boiling Water Reactor (BWR) assemblies, in addition to loose rods (uranium carbide or generic BWR and pressurized water reactor rods).

This letter authorization request uses the RAJ-II package to ship unirradiated BWR fuel assemblies that are not currently described in Section 5.(b)(1) of the CoC. The Criticality Safety Index (CSI),

equivalent to the transport index, as defined in 10 CFR 71.59 of the RAJ-II package with a payload of two GNF 11x11 LUAs in each package, modeled with additional conservatism with respect to the SAR in Chapter 6.0 of this letter authorization request, is 11.2.

1.2 Package Description The RAJ-II package is designed for shipment by truck, ship, or rail as either a Type B(U) fissile material or Type A fissile material package. The package description of the RAJ-II container is provided in detail in the SAR (Reference 1-1). The GNF 11x11 LUA shipments only alter the contents.

M250198 Non-Proprietary Information Page 12 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 1.2.1 Packaging There are no changes to this section with the introduction of new contents; thus, Section 1.2.1 of the SAR (Reference 1-1) remains applicable. The weights and dimensions of the RAJ-II package are listed in Table 1-1 of the SAR, and the relevant drawings are listed in Section 5.(3) of the CoC.

For convenience, a summary of the package is provided here:

• The structural features of the package include an Inner Container (IC) with two compartments and an Outer Container (OC), both made of stainless steel. The energy absorbing features include vibro-isolating devices and shock absorbers (balsa wood and paper or aluminum honeycomb). Lifting and tie down and package closure features remain the same as that described in the SAR.

• Unirradiated fuel has negligible decay heat; therefore, the RAJ-II package is not designed for dissipating heat.

• The fuel rod cladding and ceramic nature of the fuel pellets provide primary containment of the radioactive material.

• Due to the nature of the unirradiated payload, no biological shielding is necessary or provided by the RAJ-II package.

• The RAJ-II package does not require specific design features to provide neutron moderation and absorption for criticality control. The GNF 11x11 LUA specific Criticality Safety Analysis (CSA) is discussed in Chapter 6.0.

1.2.2 Contents A maximum of two fuel assemblies are placed in each package. The package is designed and analyzed to ship fuel assembled in an 11x11 array of fuel rods without a fuel channel (unchanneled). The GNF 11x11 bundle is a fuel assembly comprised of 112 fuel rods in a square array with a maximum active fuel rod length of <385 cm. The GNF 11x11 LUA has a single, centrally located, axially varying (in diameter) water rod which occupies a 3x3 space in the lattice.

The GNF 11x11 bundle has 20 Part Length Rods (PLRs).

The fuel pellets located in rods and contained in the packaging are Uranium Dioxide (UO2). The GNF 11x11 LUA fuel assembly average enrichment is less than or equal to 5.0 wt% Uranium-235 (U-235). The fuel rod maximum enrichment is less than or equal to 5.0 wt% U-235. The CSA does not credit the gadolinia that is expected to be in the GNF 11x11 LUAs for criticality control; therefore, there is no requirement for the minimum gadolinia concentration for shipments of GNF 11x11 LUAs.

The GNF 11x11 LUAs are planned to use commercial grade uranium and contain a Type A quantity of material as defined in Section 1.2.2.1 of the SAR (Reference 1-1). Further details of the radioactive materials for the GNF 11x11 LUA shipments are summarized below. Also see Table 1-1.

M250198 Non-Proprietary Information Page 13 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

• Main Nuclides: low enriched uranium less than or equal to 5 wt% U-235

• State of Uranium: solid UO2 ceramic pellet with authorized allowance for increased silicon concentration (Reference 1-4)

• Maximum Assembly and Pellet Enrichment: 5 wt%

• Number of fuel rods containing gadolinia: none required

• Weight of the UO2 pellets per assembly: (( ))

The payload of the GNF 11x11 LUA shipments is two assemblies per package, and the maximum payload mass complies with the limits of the CoC (684 kg) (Reference 1-2).

The chemical properties, type, and density of the materials in the RAJ-II are unchanged and described in Section 1.2.2.2 of the SAR (Reference 1-1).

1.2.3 Special Requirements for Plutonium This section of the SAR is not applicable. The GNF 11x11 LUAs will not contain plutonium.

1.2.4 Operational Features The RAJ-II package is not considered operationally complex. Operational procedures and instructions for loading, unloading, and preparing empty RAJ-II packages for transport are provided in Chapter 7.0 of the SAR (Reference 1-1).

1.3 References 1-1 Global Nuclear Fuel, GNF Safety Analysis Report, NEDE-33869P, Revision 11, September 2022, as amended.

1-2 RAJ-II Certificate of Compliance No. 9309, Docket Number 71-9309, Revision 14, Package Identification No. USA/9309/B(U)F-96, July 2023 1-3 GE Hitachi Nuclear Energy, GE Hitachi Nuclear Energy Quality Assurance Program Description, NEDO-11209-A, Revision 17, December 2022.

1-4 Yoira Diaz-Sanabria (NRC) to Brian R. Moore (GNF), Letter Authorization to Use the Model No. RAJ-II Package with an Increased Maximum Authorized Fuel Pellet Silicon Concentration, September 6, 2024.

1-5 Scott Murray (GNF) to Document Control Desk (NRC), GNF-A Request for Letter Authorization to Use the RAJ-II Package, SPM 14-030, July 30, 2014.

1.4 GNF 11x11 LUA Design Description GNF plans to ship LUAs starting in 2026 as part of the GNF 11x11 LUA new product introduction program. These bundles, also referred to as GNF 11x11 LUAs or GNF 11x11 fuel, are planned to be in operation as part of a joint program with nuclear utility customers.

M250198 Non-Proprietary Information Page 14 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis This section contains information provided to the NRC as reference information supporting the GNF request for approval to ship GNF 11x11 LUA bundles using the Model No. RAJ-II package, CoC Number 9309.

Included in this section are a description of the GNF 11x11 LUAs and a comparison to the parameters of the currently approved contents for fresh fuel shipments using the RAJ-II package.

This information is intended to provide the NRC with additional relevant information.

1.4.1 GNF 11x11 Fuel Product Description GNF 11x11 fuel is designed to be compatible with previous GE/GNF fuel designs and includes many proven features of the GE10, GE11/13, GE12, GE14, GNF2, and GNF3 fuel designs.

However, the new fuel type introduces the key feature of an 11x11 fuel rod lattice which results in several parameters which differ from previous designs. The GNF 11x11 LUAs are compared to the previously approved RAJ-II contents and parameters which differ from the existing RAJ-II CoC are addressed.

1.4.1.1 Parameters Within CoC Range The GNF 11x11 design is an evolution of the GNF3 design. The materials used in the GNF 11x11 fuel bundle are consistent with prior GNF fuel assemblies deployed in the BWR operating fleet.

The single axially varying water rod occupies a 3x3 (or 9 fuel rod equivalent spaces) area throughout the fuel bundle. Similar to the GNF2 and GNF3 fuel bundles, the GNF 11x11 LUA uses 8 tie rods, denoted by T in the Figure 1-1 bundle layouts, which extend the full length of the bundle and connect the Upper Tie Plate (UTP) and Lower Tie Plate (LTP). The maximum payload weight and the fuel concentrations are within the approved contents of the RAJ-II package.

1.4.1.2 Parameters Unique to GNF 11x11 LUAs The GNF 11x11 lattice layout by axial zone is shown in Figure 1-1. The GNF 11x11 bundle design consists of 112 fuel rods and one large central water rod. The diameter of the water rod varies with a smaller diameter at the top and bottom of the axial length of the bundle as shown in Figure 1-1.

The water rod extends to the top of the GNF 11x11 bundle and slots into the UTP.

The fuel bundle schematic is shown in Figure 1-2. The PLRs have a shorter length than the full height of the assembly and do not reach the UTP. The short PLRs ((

)) are represented by an S in the bundle schematic. The long PLRs, represented by an L in the bundle schematic, ((

)) rods and do not reach the UTP. The GNF 11x11 design has a total of 20 PLRs, which is greater than the maximum of 16 PLRs specified in Table 3 of the CoC (Reference 1-2).

A comparison of fuel parameter values for the approved GNF 10x10 fuel designs and the GNF 11x11 LUA bundle are shown in Table 1-1. This table provides the nominal product-specific values for the GNF 11x11 LUA bundle. The general parameters for 10x10 bundles in the existing CoC are shown for comparison.

M250198 Non-Proprietary Information Page 15 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 1 GNF 11x11 Lattice Layout by Axial Zone

M250198 Non-Proprietary Information Page 16 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis GNF3 GNF 11x11 Figure 1 Fuel Bundle Assembly Schematics, GNF3 (10x10) and GNF 11x11

M250198 Non-Proprietary Information Page 17 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 1 Comparison of Fuel Assembly Parameters for the Approved GNF 10x10 Designs and the GNF 11x11 LUA Parameter Units GNF 10x10 a GNF3 (Reference 1-5)

GNF 11x11 LUA Maximum Weight of UO2 Pellets per Fuel Assembly kg 275 223

(( ))

UO2 Density 98% Theoretical Number of Water Rods 0, 2-2 x 2 off-center diagonal, 3x3, 1 -axially varying centered 1 - center axially varying 1 - center axially varying b Number of Fuel Rods91-100 96 112 Fuel Rod Outer Diameter (OD) cm 1.010 1.026

(( ))

Fuel Pellet OD cm 0.895 0.888

(( ))

Cladding Type Zirconium Alloy Cladding Inner Diameter (ID) cm 0.934 0.906

(( ))

Cladding Thickness cm 0.038 0.060

(( ))

Active Fuel Length cm 385 381 385 Fuel Rod Pitch cm 1.363

(( ))

U-235 Pellet Enrichment wt%

5.0 Lattice Average Enrichment wt%

5.0 Channel Thickness cm Any Shipped Unchanneled Partial Length Fuel Rods Max#

16 16 20 Gadolinia Requirements wt%

Gd2O 3

At least 2 wt% for enrichment >2.9 wt% U-235 None Planned for LUA Special Authorization c Polyethylene Equivalent Mass per Assembly kg 10.2 Thermal Performance Criteria MPa r/t (Pf 921/293 - Pa) 31.1 MPa (4,514 psi) a From CoC Number 9309, Table 3.

b See Section 1.4.1.2.

c The criticality analysis does not take credit for gadolinia. To be finalized at the time of NRC approval.

M250198 Non-Proprietary Information Page 18 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 1.4.2 Conclusion The GNF 11x11 LUA design is an evolution of the GNF3 10x10 design. The new key feature of the GNF 11x11 is the lattice design, which changes several fuel parameters as summarized in Table 1-1. Differences in the safety bases due to the new 11x11 lattice and fuel rod design are discussed in Chapters 2.0, 3.0, 4.0, and 6.0.

M250198 Non-Proprietary Information Page 19 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.0 STRUCTURAL EVALUATION This chapter presents evaluations demonstrating that the RAJ-II package meets applicable structural criteria with the introduction of GNF 11x11 LUAs and provides necessary structural inputs for other sections. Those sections affected by the differences between the new content and currently approved contents contain evaluations to demonstrate compliance with relevant criteria, and those sections unaffected by these differences clearly state that the text in the current RAJ-II SAR (Reference 2-1) remains applicable. The 11x11 fuel design is compared to the most similar approved contents reference case of the GNF RAJ-II SAR (Reference 2-1) and approving RAJ-II CoC (Reference 2-2). The GNF3 10x10 fuel assembly is the most similar approved contents reference case because the 11x11 design is an evolution of the GNF3 design with an 11x11 fuel rod lattice.

The RAJ-II package continues to include unirradiated fuel assemblies which consist of fuel rods that provide containment, an IC, and an OC with honeycomb spacers. Existing analyses using analytical and empirical techniques demonstrating compliance to the requirements of 10 CFR 71 for Normal Conditions of Transport (NCT) and Hypothetical Accident Conditions (HAC),

included in Reference 2-1, are referenced as applicable.

The RAJ-II certification testing involved two full-scale Certification Test Units (CTUs) at Oak Ridge, TN. The RAJ-II CTUs were subjected to a series of free drop and puncture drop tests. The RAJ-II CTUs protected the simulated fuel assemblies, allowing them to remain undamaged and leak tight throughout certification testing. Details of the certification test program are provided in Section 2.12.2 of Reference 2-1. Instrumented tests of the RAJ-II container were also performed at Global Nuclear Fuel - Japan (GNF-J). The GNF-J test data is used to benchmark and develop RAJ-II analytical models which simulate the response of the RAJ-II package and the 11x11 fuel bundle. The benchmarked simulation results demonstrate that the unchanneled GNF 11x11 LUA performs acceptably in the RAJ-II under the applicable transportation conditions.

2.1 Description of the Structural Design 2.1.1 Discussion A comprehensive discussion of the RAJ-II package design and configuration is provided in Chapter 1.0 of Reference 2-1. Drawings provided in Section 1.3.1 of Reference 2-1 apply to this letter authorization request and are unchanged. These drawings illustrate the construction of the RAJ-II, and how it protects the fuel assemblies. The following characteristics of the package design remain unchanged from Reference 2-1.

• The containment is provided by the fuel cladding and welded end plugs of the fuel rods.

The 11x11 fuel rod manufacturing process uses the same standards as the approved GNF3 reference case.

• The fuel is protected by an IC that provides thermal insulation and soft foam that protects the fuel from vibration. The IC is supported by a vibration isolation system inside the OC

M250198 Non-Proprietary Information Page 20 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis that has shock absorbing blocks of balsa and honeycomb made of resin impregnated kraft paper or aluminum (hereinafter called honeycomb).

• There are no changes in the fabrication methods of the RAJ-II package.

2.1.2 Design Criteria There are no changes to this section with the introduction of new contents; thus, Section 2.1.2 of the SAR (Reference 2-1) remains applicable. However, a supplemental evaluation specific to the 11x11 fuel bundle is provided in Section 2.7 to qualify its structural performance in the bounding HAC drop scenarios analytically and provide structural inputs to subsequent criticality and thermal evaluations.

2.1.3 Weights and Centers of Gravity The maximum gross weight of an RAJ-II package, including a maximum payload weight of 684 kg (1,508 lb), is 1,614 kg (3,558 lb) and remains unchanged in this letter authorization request. The maximum vertical Center of Gravity (CG) is unchanged from Section 2.1.3 of Reference 2-1. The maximum horizontal shift of the horizontal CG is unchanged from Section 2.1.3 of Reference 2-1.

The content, IC and OC weights provided in Table 2-1 of Reference 2-1 are bounding for the GNF 11x11 contents.

2.1.4 Identification of Codes and Standards for Package Design The radioactive isotopic content of the GNF 11x11 fuel assembly is unchanged from the GNF3 fuel assembly reference case and from that discussed in Section 2.1.4 of Reference 2-1. There are no changes to this section with the introduction of the new contents; thus, Section 2.1.4 of the SAR (Reference 2-1) remains applicable.

2.2 Materials There are no changes to this section with the introduction of new contents; thus, Section 2.2 of the SAR (Reference 2-1) remains applicable.

2.3 Fabrication and Examination There are no changes to this section with the introduction of new contents; thus, Section 2.3 of the SAR (Reference 2-1) remains applicable.

2.4 General Requirements for All Packages There are no changes to this section. The RAJ-II package design remains unchanged; thus, Section 2.4 of the SAR (Reference 2-1) remains applicable.

2.5 Lifting and Tie-Down Standards for All Packages There are no changes to this section with the introduction of new contents; thus, Section 2.5 of the SAR (Reference 2-1) remains applicable.

M250198 Non-Proprietary Information Page 21 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.6 Normal Conditions of Transport 2.6.1 Heat Due to changes in the GNF 11x11 fuel bundle parameters including fuel cladding OD and ID and the fuel pellet OD, the calculations in Sections 2.6.1.1 and 2.6.1.2 of Reference 2-1 were re-evaluated for the GNF 11x11 bundle. The results demonstrate that the conclusions of SAR Section 2.6.1 do not change.

2.6.1.1 Summary of Pressures and Temperatures The maximum temperature of 77°C (171°F) under NCT remains unchanged with the addition of new contents, and the maximum pressure of 1.33 MPa absolute (193 psia) for BWR fuel types under NCT is bounding of the GNF 11x11 fuel. Thus, Section 2.6.1.1 of the SAR (Reference 2-1) remains applicable.

2.6.1.2 Differential Thermal Expansion The construction and materials of the RAJ-II package are the same for the shipment of GNF 11x11 LUAs and thus the differential thermal expansion in the package remains negligible. The cladding of the fuel which serves as containment is not stressed due to differential thermal expansion because a gap remains between the fuel pellet and the cladding at both the cold temperature -40°C and the highest temperature the fuel could see due to the HAC is conservatively 800°C (see Chapter 3.0). The demonstration of the pellet to fuel cladding gap remains applicable for all approved fuel contents in the RAJ-II container. A similar evaluation demonstrated that the pellet-cladding gap is maintained for the proposed GNF 11x11 contents.

Differential Thermal Expansion with Standard UO2 Pellets At an ambient temperature of 20°C, the pellet OD and cladding ID for the GNF 11x11 are

(( )), respectively. The thermal strains in the pellet and cladding and the resulting gaps are calculated using the same method as in the SAR (Reference 2-1).

Table 2-1 summarizes the thermal strain in the cladding and pellets with a temperature change from 20 to -40°C (T=-60°C, T=233K).

Table 2 Thermal Contraction at -40°C Dimension Strain at -40°C (-)

Dimension at -40°C (cm)

Pellet OD

-6.49 x 10-4

((

Cladding ID

-4.44 x 10-4

))

((

))

M250198 Non-Proprietary Information Page 22 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2-2 summarizes the thermal expansion in the cladding and pellets with a temperature change from 20°C to 800°C (T = 780°C, T = 1,073 K). ((

))

Table 2 GNF 11x11 Thermal Expansion at 800°C Dimension Strain at 800°C (-)

Dimension at 800°C (cm)

Pellet OD 8.08x10-3

((

Cladding ID 5.77x10-3

))

((

))

Differential Thermal Expansion for Pellets with Increased Maximum Authorized Fuel Pellet Silicon Concentration Because the GNF 11x11 LUAs contain pellets with increased maximum silicon concentration (additive) as approved in Reference 2-3, the thermal expansion effects of the additive pellets are considered below.

The strain due to thermal expansion or contraction in the fuel pellet is equal to the following from Reference 2-4:

((

))

where T is the absolute final temperature in degrees Fahrenheit (F).

The thermal strains and resulting dimensions of the additive fuel pellets for the same conditions discussed for standard UO2 pellets above are summarized in Table 2-3.

M250198 Non-Proprietary Information Page 23 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 GNF 11x11 Additive Pellet Thermal Strains Temperature Range Strain (-)

Final Dimension (cm) 20°C to -40°C (T=-60°C, T=-40°F).

((

20°C to 800°C (T=780°C, T=1472°F)

))

((

))

2.6.1.3 Stress Calculations There are no changes to this section with the introduction of new contents; thus, Section 2.6.1.3 of the SAR (Reference 2-1) remains applicable.

2.6.1.4 Comparison with Allowable Stresses There are no changes to this section with the introduction of new contents; thus, Section 2.6.1.4 of the SAR (Reference 2-1) remains applicable.

2.6.2 Cold There are no changes to this section with the introduction of new contents; thus, Section 2.6.2 of the SAR (Reference 2-1) remains applicable. The evaluation of the differential thermal expansion/contraction for GNF 11x11 in Section 2.6.1.2 demonstrates that a positive gap remains between the fuel rod cladding and fuel pellets under the cold (-40°C) condition.

2.6.3 Reduced External Pressure There are no changes to this section with the introduction of new contents; thus, Section 2.6.3 of the SAR (Reference 2-1) remains applicable.

2.6.4 Increased External Pressure There are no changes to this section with the introduction of new contents; thus, Section 2.6.4 of the SAR (Reference 2-1) remains applicable.

M250198 Non-Proprietary Information Page 24 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.6.5 Vibration There are no changes to this section with the introduction of new contents; thus, Section 2.6.5 of the SAR (Reference 2-1) remains applicable.

2.6.6 Water Spray There are no changes to this section with the introduction of new contents; thus, Section 2.6.6 of the SAR (Reference 2-1) remains applicable.

2.6.7 Free Drop There are no changes to this section with the introduction of new contents; thus, Section 2.6.7 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package of 1,614 kg (3,558 lb); therefore, the GNF 11x11 fuel design performs the same as the approved GNF3 contents.

2.6.8 Corner Drop There are no changes to this section with the introduction of new contents; thus, Section 2.6.8 of the SAR (Reference 2-1) remains applicable. As stated in Section 2.6.8 of Reference 2-1, this test does not apply for packages exceeding 100 kg (220 lb).

2.6.9 Compression There are no changes to this section with the introduction of new contents; thus, Section 2.6.9 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package of 1,614 kg (3,558 lb).

2.6.10 Penetration There are no changes to this section with the introduction of new contents; thus, Section 2.6.10 of the SAR (Reference 2-1) remains applicable.

2.7 Hypothetical Accident Conditions Section 2.7 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package of 1,614 kg (3,558 lb). As this letter authorization request contains no change to the package design, only the potential differences in behavior of the new proposed package contents are addressed. Section 2.12.2 provides the details of the analysis used to evaluate the bounding structural HAC cases for the GNF 11x11 LUA contents.

2.7.1 Free Drop Section 2.7.1 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package of 1,614 kg (3,558 lb). As this letter authorization request contains no change to the package design, only the potential differences in behavior of the new proposed package contents are addressed. For the RAJ-II package, there are

M250198 Non-Proprietary Information Page 25 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis two primary considerations for the fuel contents (shielding integrity is not a controlling case for the reasons described in Chapter 5.0 of Reference 2-1):

1. Protect the fuel so that containment is maintained

2. Ensure that the geometry of the contents is maintained sufficiently to satisfy the safety criteria in the criticality evaluation The ability of the RAJ-II package to satisfy these two requirements is evaluated using the Finite Element Analysis (FEA) simulation software LS-DYNA. The most limiting drop orientations are vertical end drop, side drop, and CG over corner orientations as justified in Table 2-4.

Table 2 Limiting HAC Drop Orientations Orientation Justification Vertical End Drop In the vertical orientation, the full weight of the bundle loads the LTP and the bottom regions of the fuel rod cladding. Therefore, the vertical orientation maximizes axial load. ((

))

Side Drop The fuel bundle experiences the highest peak decelerations in the side drop simulations. ((

)) The simulated strain results for this orientation are highly conservative because the drop test simulations omit the cluster separators which reduce the length of unsupported rods in the LUA package.

CG-over-Corner The corner drop is an intermediate case which loads the fuel bundle with a combination of axial and lateral loads. ((

))

The RAJ-II LS-DYNA model is tuned using data from the instrumented GNF-J CTU drop data as a benchmark. Section 2.12.2.1.4 contains details of the RAJ-II benchmark modelling. The benchmarked container drop models are then modified to reflect HAC drops with 11x11 fuel bundles (and in one case, the GNF2 10x10 fuel bundle) by adjusting the weight of the simplified dummy bundles which represent the contents in the IC. The Acceleration Time Histories (ATHs) of the dummy bundles are extracted from the results of the RAJ-II model and applied to detailed models of the proposed 11x11 fuel bundle to study the dynamic response of the bundle. The

M250198 Non-Proprietary Information Page 26 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis detailed bundle evaluation is split into two main analyses. The cladding strain analysis in Section 2.12.2.2.2 models the detailed bundle drops in various orientations to assess the integrity of the fuel rod cladding to ensure containment. The lattice expansion model in Section 2.12.2.2.3 uses several bounding assumptions to determine a conservative value of rod-to-rod pitch expansion for the criticality safety assessment in Chapter 6.0.

There are two main acceptance criteria used to assess the performance of the fuel bundle:

1. The integrity of the fuel rod cladding is assessed by comparing the maximum post-drop total equivalent strain simulated in the fuel rod cladding to the true Uniform Elongation (UE) strain of the zirconium alloy cladding material. The UE strain limit is a conservative criterion which leaves margin to the final fracture strain of the fuel rod cladding.

2. The fuel lattice must be maintained, and the rod-to-rod pitch expansion must be within acceptable limits for the criticality evaluation.

2.7.1.1 End Drop The analysis described in Section 2.12.2.2.2.1 and the cladding strain results reported in Section 2.12.2.2.2.4 demonstrate that the cladding integrity and lattice arrangement are maintained for the GNF 11x11 LUAs in the end drop condition. The maximum lattice expansion is assessed in the end drop orientation using several bounding assumptions as documented in Section 2.12.2.2.3. The maximum bounding fuel rod pitch expansion for GNF 11x11 LUAs is 5.69% of the nominal rod-to-rod pitch value.

2.7.1.2 Side Drop The analysis described in Section 2.12.2.2.2.2 and the cladding strain results reported in Section 2.12.2.2.2.4 demonstrate that the cladding integrity and lattice arrangement are maintained for the GNF 11x11 LUAs in the side drop condition.

2.7.1.3 Corner Drop The analysis described in Section 2.12.2.2.2.3 and the cladding strain results reported in Section 2.12.2.2.2.4 demonstrate that the cladding integrity and lattice arrangement are maintained for the GNF 11x11 LUAs in the side drop condition.

2.7.1.4 Oblique Drops As noted in Table 2-4 and in Table 2-11 of Reference 2-1, the oblique drop is not considered a limiting orientation for damage to the RAJ-II contents. Therefore, there are no changes to this section with the introduction of new contents and Section 2.7.1.4 of the SAR (Reference 2-1) remains applicable.

2.7.1.5 Horizontal Drop As noted in Table 2-4 and in Table 2-13 of Reference 2-1, the horizontal drop is not considered a limiting orientation for damage to the RAJ-II contents. Therefore, there are no changes to this

M250198 Non-Proprietary Information Page 27 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis section with the introduction of new contents and Section 2.7.1.5 of the SAR (Reference 2-1) remains applicable.

2.7.1.6 Summary of Results The strain comparison shows that the fuel rods remain well below the UE strain for all drop conditions analyzed and therefore there is significant margin to fracture under HACs. ((

))

The detailed drop models show that the fuel lattice geometry is maintained for all cases. The application of the lattice expansion value to the criticality evaluation is discussed in Chapter 6.0.

2.7.2 Crush There are no changes to this section with the introduction of new contents; thus, Section 2.7.2 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package of 1,614 kg (3,558 lb).

2.7.3 Puncture There are no changes to this section with the introduction of new contents; thus, Section 2.7.3 of the SAR (Reference 2-1) remains applicable. The new proposed contents are bounded by the maximum gross weight of the RAJ-II package.

2.7.4 Thermal There are no changes to this section with the introduction of new contents; thus, Section 2.7.4 of the SAR (Reference 2-1) remains applicable. Pressures and temperatures, hoop stress calculations, and overall allowable stresses are included in Chapter 3.0. Differential thermal expansion for the GNF 11x11 fuel rods over the full range of package temperatures is evaluated in Section 2.6.1.2.

2.7.5 Immersion - Fissile Material There are no changes to this section with the introduction of new contents; thus, Section 2.7.5 of the SAR (Reference 2-1) remains applicable.

2.7.6 Immersion - All Packages There are no changes to this section with the introduction of new contents; thus, Section 2.7.6 of the SAR (Reference 2-1) remains applicable.

2.7.7 Deep Water Immersion Test (for Type B Packages Containing More than 105 A2)

There are no changes to this section with the introduction of new contents; thus, Section 2.7.7 of the SAR (Reference 2-1) remains applicable.

M250198 Non-Proprietary Information Page 28 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.7.8 Summary of Damage There are no changes to this section with the introduction of new contents; thus, Section 2.7.8 of the SAR (Reference 2-1) remains applicable. Additionally, the worst case estimation of content deformation reported in Section 2.7.1.1 for the newly proposed contents is evaluated in Chapter 6.0.

2.8 Accident Conditions for Air Transport of Plutonium Not applicable. This package is not used for the air transport of plutonium.

2.9 Accident Conditions for Fissile Material Packages for Air Transport Not applicable. This package is not used for the air transport of fissile material.

2.10 Special Form Not applicable. This section does not apply to the RAJ-II package because special form is not claimed.

2.11 Fuel Rods There are no changes to this section with the introduction of new contents; thus, Section 2.11 of the SAR (Reference 2-1) remains applicable. Evaluations specific to the ability of the GNF 11x11 fuel rods to provide containment of the radioactive material under NCT or HAC are provided in Sections 2.12.2.2, 3.3, and 3.4.

2.12 Appendix 2.12.1 References 2-1 Global Nuclear Fuel, GNF RAJ-II Safety Analysis Report, NEDE-33869P, Revision 11, September 2022, as amended.

2-2 RAJ-II Certificate of Compliance No. 9309, Docket Number 71-9309, Revision 14, Package Identification No. USA/9309/B(U)F-96, July 2023.

2-3 Yoira Diaz-Sanabria (NRC) to Brian R. Moore (GNF), Letter Authorization to Use the Model No. RAJ-II Package with an Increased Maximum Authorized Fuel Pellet Silicon Concentration, September 6, 2024. (ADAMS Accession Number ML24247A220) 2-4 Global Nuclear Fuel, "Additive Fuel Pellets for GNF Fuel Designs," NEDC-33406P-A, Revision 3, December 2015.

2-5 American Society of Mechanical Engineers (ASME), ASME Boiler and Pressure Vessel Code 2023,Section VIII, Division 2, Subsection 3.11.5.

2.12.2 Certification by Analysis The most limiting HAC drop scenarios are applied using the FEA software LS-DYNA to the GNF 11x11 fuel design by simulating the RAJ-II container drop with simplified dummy fuel bundles

M250198 Non-Proprietary Information Page 29 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis modelled inside the IC, extracting the ATHs from the dummy bundles, and applying the ATHs to detailed models of the 11x11 fuel. The process for developing the RAJ-II model and the detailed 11x11 fuel models is documented in the following sections.

2.12.2.1 RAJ-II Container Model The RAJ-II model is developed from the RAJ-II licensing drawings in Section 1.3.1 of Reference 2-1. The model is constructed of solid objects that represent the crushable materials and surfaces for most steel components. The meshed RAJ-II model with a breakdown of the internal components is shown in Figures 2-1, 2-2, and 2-3:

((

))

Figure 2 RAJ-II LS-DYNA Finite Element Model Assemblies

M250198 Non-Proprietary Information Page 30 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 RAJ-II LS-DYNA Finite Element Component Models

M250198 Non-Proprietary Information Page 31 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 RAJ-II LS-DYNA Full Model Transverse Cross Section 2.12.2.1.1 RAJ-II Model Masses Masses of the RAJ-II LS-DYNA model are adjusted to reflect the GNF-J drop tests, GNF2 10x10 fuel, and the proposed GNF 11x11 fuel as shown in Table 2-5. Non-structural items and features such as weld material, wood screws, and plugs are omitted from the LS-DYNA model. To account for the missing mass of such items, the density of the stainless-steel components was increased to achieve the appropriate total IC and OC mass. The maximum allowable mass of the IC, 308 kg (679 lbm), and OC, 622 kg (1,371 lbm) (Reference 2-1), is modeled in all RAJ-II drop simulations.

The fuel bundle payload mass varies between LS-DYNA drop simulations. For GNF-J drop test simulations, the payload mass of 560 kg (1,235 lbm) reflects that of the 8x8 and 9x9 fuel bundle payloads (Reference 2-1). For simulations of the RAJ-II containing GNF2 fuel, a 10x10 bundle, the payload mass of 529 kg (1,167 lbm) is modeled. For simulations of the RAJ-II containing GNF 11x11 fuel, a payload mass of (( )) is modeled, representing a conservative upper bound of the unchanneled 11x11 bundle which remains within the current maximum allowed 684 kg payload weight per Section 2.1.3 of Reference 2-1.

M250198 Non-Proprietary Information Page 32 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 LS-DYNA RAJ-II Component Masses per Simulation LS-DYNA Simulation Payload kg (lbm)

Inner Container kg (lbm)

Outer Container kg (lbm)

Total Mass kg (lbm)

GNF-J Drop Test 560 (1,235) 308 (679) 622 (1,371) 1,490 (3,285)

GNF2 10x10 Payload 529 (1,167) 308 (679) 622 (1,371) 1,459 (3,217)

GNF 11x11 Payload1

(( ))

308 (679) 622 (1,371)

(( ))

Note 1: The GNF 11x11 payload represents a bounding value for the unchanneled fuel bundle.

2.12.2.1.2 Target Surface The impact target as defined by 10 CFR 71 must be a flat, horizontal, and essentially unyielding surface. The impact target for the RAJ-II package model is modeled in LS-DYNA as a rigid plane which does not permit node penetration or energy absorption.

2.12.2.1.3 Initial Conditions An initial velocity is applied to all components of the RAJ-II package to simulate the 9 m (30 ft) freefall prior to the moment of impact with the rigid surface. Knowing potential and kinetic energies are equal upon impact, the initial velocity is defined in the LS-DYNA simulation as 13.3 m/s (527.5 in/s) normal to the impact surface:

or:

where:

v = Initial velocity at the threshold of impact g = Gravitational acceleration of 9.81 m/s2 (386.4 in/s2) h = Drop height of 9 m (360 inches) 2.12.2.1.4 Benchmark of LS-DYNA Simulations with CTU Drop Tests Drop simulations at nominal conditions are benchmarked against the nominal condition CTU drop tests. Fuel bundle decelerations, both peak values and overall durations, and package deformations show reasonable agreement with CTU drop test data.

1 2 mv2 = mgh v = 2gh=13.3 m/s (527.5 in/s)

M250198 Non-Proprietary Information Page 33 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 2.12.2.1.4.1 End Drop Benchmark The CTU-1J 9 m (30 ft) vertical end drop was oriented over the lower end (i.e., nearest the LTP).

The ATH measured at the side face of the center of the IC is shown as a dashed line in Figure 2-4.

A peak deceleration of 303 g is reported.

IC deceleration data of the LS-DYNA simulation of the CTU-1J vertical end drop is shown with solid lines in Figure 2-4. The peak deceleration of the side face of the center of the IC is (( ))

and is representative of the drop test data.

((

))

Figure 2 End Drop Inner Container Decelerations for CTU-1J 2.12.2.1.4.2 Top Drop Benchmark The top drop is not a drop orientation that is considered for the GNF 11x11 LUAs because simulation of the side drop resulted in more severe deceleration for the horizontally oriented fuel bundle. However, data from the CTU-2J top drop is used to benchmark the overall RAJ-II model because there is no test data for the side drop. Of the CTU drops, the top drop is most comparable to the side drop because, for both cases, the fuel is oriented horizontally with respect to the target surface and the energy absorbers are oriented similarly with respect to the IC.

The deceleration ATHs measured at the outer shell of the IC and center spacer of the fuel bundle are shown in Figure 2-5 and 2-6, respectively. A peak deceleration of 194 g and 145 g is reported for the IC and fuel bundle respectively.

Deceleration data of the LS-DYNA simulation of the CTU-2J top drop is shown as a solid-line in Figure 2-5 and 2-6. Peak decelerations of (( )) were calculated for the IC shell and fuel bundle, respectively. The overall structure of the OC was maintained in the simulation.

M250198 Non-Proprietary Information Page 34 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 Top Drop Inner Container Decelerations for CTU-2J

((

))

Figure 2 Top Drop Fuel Bundle Decelerations for CTU-2J 2.12.2.1.4.3 Corner Drop Benchmark The CTU-1J 9 m (30 ft) corner drop was oriented with the CG over the bottom face corner of the package upper end (i.e., nearest the UTP). The deceleration measured at the LTP of the fuel assembly is shown as a dashed line in Figure 2-7. A peak acceleration of 203 g is reported.

M250198 Non-Proprietary Information Page 35 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Deceleration data of the LS-DYNA simulation of the corner drop is shown as a solid-line in Figure 2-7. The peak deceleration of the fuel bundle is (( )). The overall structure of the OC was maintained, but with localized plastic deformation.

((

))

Figure 2 Corner Drop Fuel Bundle Decelerations for CTU-1J 2.12.2.1.5 GNF 11x11 Bundles in the RAJ-II LS-DYNA Results To determine the decelerations imparted on the proposed GNF 11x11 LUA bundles in the limiting orientations defined in Table 2-4, the benchmarked GNFJ CTU models described in Section 2.12.2.1.4 are modified to match the 11x11 and 10x10 GNF2 bundle weights shown in Table 2-5. The ATH curves are used as inputs to the detailed bundle models in the following sections.

The detailed fuel bundle (see Section 2.12.2.2) is modelled to conservatively represent the regulatory temperature range of -40 to 77°C across several run cases. ATHs for the 77°C condition detailed fuel bundle models are taken from the nominal condition 11x11 RAJ-II models. This is a conservative treatment because no credit is taken for the decrease in the RAJ-II energy absorber stiffnesses due to the elevated temperature. For the -40°C detailed fuel bundle models, the ATHs are taken from the RAJ-II models with the worst-case materials which account for increased stiffness due to changes in moisture, temperature, and density. The application of the worst-case ATHs to the -40°C detailed model is conservative due to the combination of stiffening factors applied to the RAJ-II materials and due to the use of mostly room-temperature material properties in the -40°C detailed material models which takes reduced credit for the increased strengths of the bundle materials at sub-zero temperatures. For consistency with the nomenclature of the detailed fuel bundle models, the worst-case and nominal ATHs are henceforth referred to as the -40°C and 77°C curves, respectively. The 11x11 dummy fuel bundle ATHs for various cases are summarized in Figure 2-8 (End Drop), Figure 2-9 (Side Drop), Figure 2-10 (Corner Drop -40°C), and

M250198 Non-Proprietary Information Page 36 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Figure 2-11 (Corner Drop 77°C). The corner drop results include acceleration curves for X, Y, and Z directions due to the models asymmetrical orientation. The -40°C GNF2 10x10 end drop ATH, which is used as a bounding deceleration input for the lattice expansion evaluation (Section 2.12.2.2.3) is shown in Figure 2-12.

((

))

Figure 2 11x11 End Drop Fuel ATH

((

))

Figure 2 11x11 Side Drop Fuel ATH

M250198 Non-Proprietary Information Page 37 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 11x11 Corner Drop Fuel ATH, -40°C

((

))

Figure 2 11x11 Corner Drop Fuel ATH, 77°C

M250198 Non-Proprietary Information Page 38 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 GNF2 10x10 End Drop Fuel ATH, -40°C 2.12.2.2 Detailed 11x11 Fuel Bundle Models The ATH curves represent the loads imparted on the fuel contents during HAC 9m drops, but they do not capture the dynamic behavior of the fuel bundle. Thus, detailed models of the GNF 11x11 fuel bundles are developed to model the response of the fuel bundle and the resulting damage to individual components, namely, the fuel rod cladding. A total of six cases are evaluated. Two of each drop orientation (end drop, horizontal side drop, and a CG-over-corner drop) are evaluated using properties and ATH curves representing drops at -40°C and 77°C, respectively. The setup methods for the drop models are documented in the following sections.

2.12.2.2.1 11x11 Detailed Model Material Properties There are four main material models used in the GNF 11x11 assembly model: the Zircaloy-2 (Lower End Plugs (LEPs)) and Ziron (cladding) which are zirconium alloys that share the same properties and make up the fuel rods, the stainless steel LTP, the Inconel X-750 steel spacers, and the UO2 fuel pellets. The material models are calculated for various temperatures to represent the regulatory temperature range of -40°C to 77°C. However, data for material properties at sub-zero temperatures is limited, so in some cases, room temperature properties are conservatively used.

This treatment is conservative because room temperature properties do not take credit for any increase in stiffness or strength due to low temperature. As noted in the ASME Boiler and Pressure Vessel Code (BPVC), impact performance is not hindered for zirconium alloys above a temperature of -59°C (Reference 2-5).

The detailed fuel bundle model uses elastic-plastic material models for the main structural elements of the fuel bundle including the zirconium alloy fuel rods, stainless steel LTP, and Inconel steel spacers. The stainless steel and zirconium alloy materials are of primary concern because they make up the package containment boundary and lattice arrangement. Thus, the stainless steel

M250198 Non-Proprietary Information Page 39 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis and zirconium alloy material models also account for strain rate effects over a range of loading rates to simulate an appropriate stress-strain response for impact conditions.

((

))

2.12.2.2.2 Cladding Strain Model The following model setups are used to evaluate the 11x11 fuel bundle in the three most limiting drop orientations discussed in Table 2-4. Each model orientation is run in the -40°C and 77°C condition by applying the corresponding material properties and load curves discussed in Sections 2.12.2.2.1 and 2.12.2.1.5, respectively.

2.12.2.2.2.1 Cladding Strain Vertical End Drop The bundle is modelled to land perfectly on its end in the vertical end drop configuration so the strain and deformation are largely symmetrical. Therefore, the bundle is modelled with a half-symmetry region along the Y-Z plane.

The fuel bundle is loaded by twice integrating ATHs developed in Section 2.12.2.1.5 into a position versus time curve and applying the resulting displacement to the seating surface of the LTP. The LTP bail is conservatively ignored because the fuel mainly rests on y-blocks in the IC which interface with the LTP seating surface as shown in Figure 2-13. Because the fuel bundle is only modelled up to the midpoint of the second spacer, the remainder of the fuel bundle mass is simulated by adding mass elements to the cut plane of the fuel cladding and the top surfaces of the fuel pellets.

M250198 Non-Proprietary Information Page 40 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 2 Cladding Strain Vertical End Drop Model For the end drop orientation, the following pre-loads are applied to the bundle:

• Tie rod pre-tension and the corresponding compression on non-tie fuel rods

• Internal fill gas pressure for all fuel rods

• Maximum expansion force applied to the inner wall of the LTP by the filter assembly 2.12.2.2.2.2 Cladding Strain Side Drop The bottom span of the bundle is also studied for the side drop orientation, as shown in Figure 2-14.

((

)) Therefore, the bottom two spacer spans of the fuel are the most limiting in a side drop. The horizontal side drop uses largely the same model setup as the end drop model with the following exceptions:

1. There are no mass nodes representing the upper bundle assembly above the cut plane at the axial mid-point of the second spacer. The mass of the upper assembly has a negligible

M250198 Non-Proprietary Information Page 41 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis effect on the lower cladding in the side impact, so a symmetry region is applied to the cladding along the cut plane rather than a mass node sent and due to this symmetry region, the expansion spring preloads are not included in the side drop model.

2. Because the spacer deflection/stiffness is important for the response of the side drop orientation, the stiffness of the spacer springs and stops are considered by adding spring elements to the space between the spacer cells and cladding.

3. The Y-direction ATH from the RAJ-II container dummy model is applied via uniform body load. The acceleration causes the bundle to land on a rigid analytical surface normal to the Y-axis.

((

))

Figure 2 Cladding Strain Horizontal Side Drop Model The setup of the side drop model is highly conservative because for unchanneled shipments of GNF fuel, cluster separators are inserted between the fuel rod lattice between each spacer span.

The cluster separators reduce the length of unsupported weight and reduce the motion of the fuel rods in a drop accident. Therefore, the fuel rod cladding strain calculated is bounding of a real horizontal drop scenario.

2.12.2.2.2.3 Cladding Strain Corner Drop The corner drop model requires a model of the 11x11 lattice with no lateral symmetry region due to its irregular drop angle. To simulate a realistic response given the asymmetrical drop angle, the horizontal side drop model is mirrored about the Y-Z symmetry plane to create a representation of the full 11x11 lattice below the midpoint of the second spacer, as shown in Figure 2-15. The only addition to the side model that is made before mirroring the model is to add the same mass node sets used in the vertical end drop to simulate the upper bundle mass. The entire half-symmetry

M250198 Non-Proprietary Information Page 42 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis model is then mirrored to create the full 11x11 lower bundle model and rotated to match the orientation of the RAJ-II container corner drop model (see Section 2.12.2.1.5). The impact load is applied by a similar method to the side drop orientation, but body loads are applied in all three directions corresponding to the ATHs in Figure 2-10 and Figure 2-11. Three analytical surfaces are defined opposite of the direction of motion of the bundle to represent the IC walls.

((

))

Figure 2 Cladding Strain Corner Drop Model 2.12.2.2.2.4 Cladding Strain Model Results The results of the detailed fuel bundle models are discussed below. A summary of the cladding strain results is shown in Table 2-6.

M250198 Non-Proprietary Information Page 43 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 GNF 11x11 Fuel Cladding Strain Results Drop Case Maximum Total Strain Maximum Plastic Strain Allowable Strain Vertical End Drop, -40°C

((

13.4%

Vertical End Drop, 77°C Corner Drop, -40°C Corner Drop, 77°C Side Drop, -40°C Side Drop, 77°C

))

The maximum strain for all cases occurs in the corner drop orientation. The maximum strain occurs in a full length rod approximately 27 mm (1.06 inches) above the LEP weld as shown in Figure 2-16.

((

))

Figure 2 Overall Maximum HAC Cladding Strain - Corner Drop, -40°C 2.12.2.2.3 Lattice Expansion Model The lattice expansion model is a specific case of the detailed fuel bundle model which uses conservative assumptions to determine a maximum bounding value for the percentage increase of

M250198 Non-Proprietary Information Page 44 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis the fuel bundle rod-to-rod pitch. The following assumptions were made to simplify the model and provide a bounding input for the percentage lattice expansion for the Chapter 6.0 criticality evaluation for GNF 11x11 LUA shipments:

1. The lattice expansion model uses the worst case, -40°C end drop ATH from the GNF2 container drop simulation (see Figure 2-12). The GNF2 dummy bundle curve has a more severe deceleration than the 11x11 dummy bundle due to the lower payload weight which reduces the crush stroke of the energy absorbing material.

2. In the lattice expansion model, the GNF2 -40°C end drop ATH is applied to a bundle model which uses the 77°C material properties. This treatment is conservative as it combines the worst-case acceleration, and worst-case bundle response.

3. The fuel pellets are excluded from the lattice expansion model. Instead, the effect of the fuel pellets in the assembly model is accounted for by uniformly lumping their mass into the fuel rod LEPs.

The above assumptions result in a lattice expansion which has conservative margin to a realistic drop scenario.

The lattice expansion is only a concern for the HAC vertical drop because the horizontal and corner drop cases cause all fuel rods to deflect in the same direction, decreasing the distance between the rods. In the vertical drop however, the fuel bundle is modelled to land perfectly on its end, causing the fuel rods to expand symmetrically with respect to the fuel bundle axial centerline at some cross sections. Thus, symmetry is used to study an axial quarter-slice of the fuel bundle. Because the rods expand symmetrically, the percentage lattice expansion of one quarter segment is representative of the total lattice expansion of the bundle. The change in pitch between two adjacent rods in the 11x11 bundle is determined from the nodal results of the FEA simulation according to Figure 2-17.

Figure 2 Rod Pitch Change The percentage change in pitch for each rod pair, P is calculated according to the following equation:

M250198 Non-Proprietary Information Page 45 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis The setup of the lattice expansion model is largely the same as that of the cladding strain model in Section 2.12.2.2.2, except that the bundle is split using quarter-symmetry along the axial length of the bundle and the mass of the fuel pellets are lumped into the lower end plugs rather than modelling the pellets within the fuel cladding. The pellet weight is included in the fuel rod plugs by uniformly altering their density. This results in a larger share of the bundle mass concentrated at the center of the LTP, which is conservative for the end drop orientation. The lattice expansion model setup is depicted in Figure 2-18.

((

))

Figure 2 Lattice Expansion Model Setup The percentage change in pitch is recorded at three arbitrary timesteps after the drop event for each pair of adjacent rods at the lateral fuel rod cross section that corresponds to the greatest cladding deflection after the simulated bundle comes to rest after the drop event. The axial location with the overall greatest nodal deflection is selected, and the average of the results at three time steps accounts for variations due to small oscillations that remain in the bundle simulation post-drop.

After the individual pitch changes are recorded, the overall average percentage pitch change is calculated. The post-drop rod pitch measurements are recorded in Table 2-7, Table 2-8, and Table 2-9. The corresponding results are plotted in Figure 2-19, Figure 2-20, and Figure 2-21,

= (,, )

100

M250198 Non-Proprietary Information Page 46 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis respectively. Finally, the average of the lattice expansion values sampled in the three timesteps is reported in Table 2-10.

M250198 Non-Proprietary Information Page 47 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 Expansion at First Time-Step

((

))

((

))

Figure 2 First Time-Step Post-Drop Position Plot

M250198 Non-Proprietary Information Page 48 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 Expansion at Second Time-Step

((

))

((

))

Figure 2 Second Time-Step Post-Drop Position Plot

M250198 Non-Proprietary Information Page 49 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 2 Expansion at Third Time-Step

((

))

((

))

Figure 2 Third Time-Step Post-Drop Position Plot Table 2 GNF4 11x11 Overall Lattice Expansion Lattice Expansion 5.69%

M250198 Non-Proprietary Information Page 50 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 3.0 THERMAL EVALUATION This chapter presents evaluations demonstrating that the RAJ-II package meets applicable thermal criteria with the introduction of the new unchanneled GNF 11x11 fuel assembly contents and provides necessary thermal inputs for other sections. Those sections affected by the differences between the new content and currently approved contents contain evaluations to demonstrate compliance with relevant criteria, and those sections unaffected by these differences clearly state that the text in the current RAJ-II SAR (Reference 3-1) remains applicable. The GNF 11x11 fuel assembly design is compared to the most similar approved contents reference case of the GNF RAJ-II SAR, Docket Number 71-9309, Revision 11, as amended (Reference 3-1), and approving RAJ-II CoC Number 9309 Revision 14 (Reference 3-2). The GNF3 10x10 fuel assembly is the most similar approved contents reference case because the 11x11 design is an evolution of the GNF3 design with an 11x11 fuel rod lattice.

3.1 Description of Thermal Design Consistent with the RAJ-II SAR (Reference 3-1), the RAJ-II package continues to include unirradiated fuel assemblies which consist of fuel rods that provide containment, an IC, and an OC which provide thermal protection for the contents. The IC and OC restrict the exposure of the fuel to external heat loads. The fuel assemblies have negligible decay heat.

There are no changes to this section with the introduction of new contents; thus, Section 3.1 of the SAR (Reference 3-1) remains applicable. There are no change to the packaging materials of construction, the IC, the OC, or the thermal insulation of the IC.

3.1.1 Design Features There are no changes to this section with the introduction of new contents; thus, Section 3.1.1 of the SAR (Reference 3-1) remains applicable.

3.1.2 Contents Decay Heat There are no changes to this section with the introduction of new contents; thus, Section 3.1.2 of the SAR (Reference 3-1) remains applicable. The contents are unirradiated fuel; thus, the decay heat is negligible.

3.1.3 Summary Tables of Temperatures There are no changes to this section with the introduction of new contents; thus, Section 3.1.3 of the SAR (Reference 3-1) remains applicable.

3.1.4 Summary Tables of Maximum Pressures There are no changes to this section with the introduction of new contents; thus, Section 3.1.4 of the SAR (Reference 3-1) remains applicable.

M250198 Non-Proprietary Information Page 51 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 3.2 Material Properties and Component Specifications 3.2.1 Material Properties There are no changes to this section with the introduction of new contents; thus, Section 3.2.1 of the SAR (Reference 3-1) remains applicable.

3.2.2 Component Specifications There are no changes to this section with the introduction of new contents; thus, Section 3.2.2 of the SAR (Reference 3-1) remains applicable.

3.3 Thermal Evaluation Under Normal Conditions of Transport This section presents the results of the thermal analysis of the RAJ-II package for the NCT specified in 10 CFR 71.71. The maximum temperature of the IC for the NCT is used as input (initial conditions) in the HAC (fire event) analysis.

3.3.1 Heat and Cold There are no changes to this section with the introduction of new contents; thus, Section 3.3.1 of the SAR (Reference 3-1) remains applicable. Section 3.5.3 of Reference 3-1 contains details applicable to NCT thermal transient analysis.

3.3.2 Maximum Normal Operating Pressure There are no changes to this section with the introduction of new contents; thus, Section 3.3.2 of the SAR (Reference 3-1) remains applicable.

3.4 Thermal Evaluation Under Hypothetical Accident Conditions This section presents the results of the thermal analysis of the RAJ-II package for the HAC specified in 10 CFR 71.73. There is no change to the RAJ-II package design; therefore, only the potential differences in behavior of the new proposed package contents are addressed.

3.4.1 Initial Conditions There are no changes to this section with the introduction of new contents; thus, Section 3.4.1 of the SAR (Reference 3-1) remains applicable.

3.4.2 Fire Test Conditions There are no changes to this section with the introduction of new contents; thus, Section 3.4.2 of the SAR (Reference 3-1) remains applicable. The HAC thermal analysis described in Section 3.4.2 of the SAR (Reference 3-1) does not model the fuel contents. The peak temperature of the inner face of the IC stainless steel is conservatively applied to the fuel rods for the HAC thermal evaluations. Because there is no change to the package design, there is no change to the HAC thermal model.

M250198 Non-Proprietary Information Page 52 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 3.4.3 Maximum Temperatures and Pressure The GNF 11x11 fuel assembly ((

)) which is bounded by the maximum ambient temperature BWR fuel rod pressurization of (( )) used in Section 3.4.3.2 of the RAJ-II SAR (Reference 3-1). Because the RAJ-II HAC model is unchanged with the addition of new contents, the maximum HAC temperature of 648°C is unchanged and the maximum internal pressure calculations in Section 3.4.3.2 of the SAR (Reference 3-1) remain applicable.

Section 3.4.3 of the SAR (Reference 3-1) provides an 800°C maximum temperature limit based on rupture test data. RAI response 3-2 of Reference 3-3 established a method of using PRIME cladding creep relations and material properties (Reference 3-4) to predict the failure temperatures of other, untested rods. For the 11x11 fuel rods, that method was similarly repeated. ((

)) Table 2-6 predicts a maximum initial HAC drop strain of (( )) which is bounded by the (( )) used in the analysis. It should be noted that the Reference 3-3 RAI response used a limit of 15% total strain. This analysis does not change that limit, but accounts for the initial strain by reducing the cladding thickness according to an initial axial strain of (( )) and assuming rupture occurs at ((

)). Because the predicted failure temperature at the conservatively assumed (( )) rupture strain is above the existing failure temperature, the existing maximum temperature of 800°C in the SAR (Reference 3-1) is bounding.

3.4.4 Maximum Thermal Stress The maximum thermal stress in the GNF 11x11 fuel rods is evaluated to demonstrate that the rods remain within the allowable stress limit for BWR fuel rods calculated in Section 3.4.4.1 of the SAR (Reference 3-1). The thermal stress criterion for all BWR fuel types shipped in the RAJ-II is shown in Equation (3-1) and corresponds to the maximum cladding exposure temperature of 648°C (921 K). The thermal stress criterion is evaluated for the GNF 11x11 fuel rod design dimensions (r/t) and pressures (Pf, Pa) below.

where:

/t

= GNF 11x11 cladding inner radius to thickness ratio (( ))

= GNF 11x11 absolute helium fill pressure (( ))

= Atmospheric pressure, (( ))

= BWR allowable stress at 800°C, 31.1 MPa (4,514 psi)

=

( 921 293 )

M250198 Non-Proprietary Information Page 53 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Note that the cladding outer radius is used to conservatively calculate the cladding inner radius to thickness ratio for GNF 11x11 LUAs. The GNF 11x11 design value for Pf is used rather than the

(( )) absolute value which is the generic maximum for all BWR fuel rods. The resulting thermal stress for GNF 11x11 is (( )), which is within the maximum BWR thermal stress criterion of 31.1 MPa. The thermal stress criterion remains applicable because the 31.1 MPa limit is based on a rupture temperature greater than 800°C which is determined to be applicable to GNF 11x11 as discussed in Section 3.4.3. Thus, the calculations in Section 3.4.4 of the SAR (Reference 3-1) remain applicable.

3.4.5 Accident Conditions for Fissile Material Packages for Air Transport Not applicable. This package is not used for air transport of fissile material.

3.5 Appendix 3.5.1 References 3-1 Global Nuclear Fuel, GNF RAJ-II Safety Analysis Report, NEDE-33869P Revision 11, September 2022, as amended.

3-2 RAJ-II Certificate of Compliance No. 9309, Docket Number 71-9309, Revision 14, Package Identification No. USA/9309/B(U)F-96, July 2023.

3-3 Brian R. Moore (GNF) to Document Control Desk (NRC), GNF Responses to the NRC Requests for Additional Information for Review of the Model No. RAJ-II, M170059, April 7, 2017.

3-4 Global Nuclear Fuel, "The PRIME Model for Analysis of Fuel Rod Thermal - Mechanical Performance Part 1 - Technical Bases," NEDC-33256P-A, Revision 2, October 2021

M250198 Non-Proprietary Information Page 54 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 4.0 CONTAINMENT 4.1 Description of the Containment System The radioactive material is bound in sintered ceramic pellets having very limited solubility and has minimal propensity to suspend in air. The fuel sealing method will not change with the introduction of GNF 11x11 fuel rods. Further details on the containment boundary are in Section 4.1 of the GNF RAJ-II SAR, Docket Number 71-9309, Revision 11, as amended (Reference 4-1). This letter authorization request applies where the content of the RAJ-II package is unirradiated, non-reprocessed, commercial grade uranium or other uranium materials, where the A2 value is not exceeded. This letter authorization request is for Type A quantities only.

There are no changes to this section with the introduction of new contents; thus, Section 4 of the SAR (Reference 4-1) remains applicable. There is no change to the package materials of construction, IC, or OC. The evaluations in Chapters 2.0 and 3.0 of the SAR (Reference 4-1) and the corresponding evaluations included in this letter authorization request demonstrate that the package with GNF 11x11 LUA contents do not rupture under HAC scenarios, which bound the NCT requirements for a package containing a Type A quantity of fissile material.

4.2 Containment Under Normal Conditions of Transport There are no changes to this section with the introduction of new contents because the GNF 11x11 LUA shipments only contain Type A fissile material quantities. Section 4.2 of the SAR (Reference 4-1) contains Type B fissile content evaluations for information purposes only.

4.3 Containment Under Hypothetical Accident Conditions There are no changes to this section with the introduction of new contents because the GNF 11x11 LUA shipments only contain Type A fissile material quantities. Section 4.3 of the SAR (Reference 4-1) contains Type B fissile content evaluations for information purposes only.

4.4 Leakage Rate Tests for Type B Packages There are no changes to this section with the introduction of new contents because the GNF 11x11 LUA shipments only contain Type A fissile material quantities. Section 4.4 of the SAR (Reference 4-1) contains Type B fissile content evaluations for information purposes only.

4.5 References 4-1 Global Nuclear Fuel, GNF Safety Analysis Report, NEDE-33869P, Revision 11, September 2022, as amended.

M250198 Non-Proprietary Information Page 55 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 5.0 SHIELDING EVALUATION No shielding evaluation was performed. The contents transported by the RAJ-II package are unirradiated fuel, which does not emit significant gamma or neutron radiation. The shielding evaluation performed in Chapter 5.0 of the RAJ-II SAR (Reference 5-1) assumes the maximum uranium payload mass provided in Section 1.2.2.6 of the RAJ-II SAR (Reference 5-1) to scale the source term, which is proportional to the resultant dose rate. The uranium mass of GNF 11x11 LUAs is bounded by the maximum uranium payload mass provided in Section 1.2.2.6 of the RAJ-II SAR (Reference 5-1). Therefore, the dose rate from GNF 11x11 LUAs is bounded by the results described in Section 5.4.4 of the RAJ-II SAR (Reference 5-1).

There are no changes to this section resulting from the addition of GNF 11x11 LUAs. Thus, Chapter 5.0 of the RAJ-II SAR (Reference 5-1) remains applicable.

5.1 References 5-1 Global Nuclear Fuel, RAJ-II Safety Analysis Report, NEDE-33869P, Revision 11, September 2022.

M250198 Non-Proprietary Information Page 56 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

6.0 CRITICALITY EVALUATION

This chapter presents criticality evaluations to demonstrate that the RAJ-II package meets applicable criticality criteria with the introduction of GNF 11x11 LUAs.

Chapter 6.0 sections affected by the introduction of GNF 11x11 LUAs contain evaluations to demonstrate compliance with relevant 10 CFR 71 criteria. Sections unaffected by differences from the introduction of GNF 11x11 LUAs are stated as such. Analytical techniques used to demonstrate compliance to 10 CFR 71 requirements reference the RAJ-II SAR (Reference 6-1) as applicable.

The RAJ-II package is identical to that described in Reference 6-1 and continues to include unirradiated fuel assemblies consisting of fuel rods contained within zirconium alloy cladding that provides containment (zirconium alloy cladding).

The objective of this analysis was to evaluate criticality safety for the RAJ-II package loaded with GNF 11x11 LUAs. The CSA for the RAJ-II package was performed in the RAJ-II SAR (Reference 6-1) for several types of GNF BWR fuel designs, including 8x8, 9x9 and 10x10 fuel assemblies. The GNF 11x11 LUA fuel design is similar to the GNF fuel designs evaluated in the RAJ-II SAR (Reference 6-1) and is most similar to the GNF 10x10 fuel assembly enriched 5 Weight Percent (wt%) U-235. However, fuel design configurations for GNF 11x11 LUAs are beyond the limitations established by Table 6-1 of the RAJ-II SAR (Reference 6-1). Therefore, the effect that GNF 11x11 LUA parameters have on RAJ-II package criticality safety are evaluated to support shipments of GNF 11x11 LUAs.

Due to the similarities between GNF 11x11 LUAs and GNF 10x10 fuel designs, their respective neutron mean-free paths and energies of average lethargy causing fission are comparable in the RAJ-II package. Therefore, conclusions from the RAJ-II SAR (Reference 6-1) regarding the storage and orientation of GNF 10x10 fuel assemblies are applied to GNF 11x11 LUAs.

This analysis only evaluates the package array under HAC, which was demonstrated to be the most reactive configuration and was used to determine the CSI in the RAJ-II SAR (Reference 6-1). The limiting HAC package array is determined by following the criticality evaluation methodology in Reference 6-1.

GNF 11x11 LUAs will be conservatively limited to Type A fissile material (enriched commercial grade uranium as defined by American Society for Testing and Materials (ASTM) C996). GNF 11x11 LUAs may contain additive fuel as previously approved in Reference 6-2.

6.1 Description of Criticality Design Table 6-1 provides the bounding fuel parameters for GNF 11x11 LUAs. Section 6.1 of the RAJ-II SAR (Reference 6-1) remains largely unaffected except for the GNF 11x11 fuel assembly parameters included in Table 6-1.

M250198 Non-Proprietary Information Page 57 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 6 LUA Parameters Beyond the RAJ-II SAR Affected Parameters in Table 6-1 of the RAJ-II SAR (Reference 6-1)

Units Type Fuel Assembly Type Rods GNF 11x11 LUA UO2 Density (Theoretical) 98%

Number of Water Rods 1, 3x3 (Center of Bundle)

Number of Fuel Rods

((

Fuel Rod OD cm Fuel Rod Pellet OD cm

))

Cladding Type Zirconium Alloy Cladding ID cm

((

Cladding Thickness cm

))

Active Fuel Length cm 385 Fuel Rod Pitch cm

(( ))

U-235 Pellet Enrichment wt%

5.0 Lattice Average Enrichment wt%

5.0 Channel Thickness Unchanneled Part Length Fuel Rods

(( ))

Polyethylene Equivalent Mass per Assembly kg 10.2 6.1.1 Design Features There are no changes to the design features of the RAJ-II package resulting from the addition of GNF 11x11 LUAs. Thus Section 6.1.1 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.1.2 Summary Table of Criticality Evaluation The criticality evaluation summary for BWR 8x8, 9x9, and 10x10 fuel assemblies and fuel rods, along with Canada deuterium uranium and generic pressurized water reactor fuel rods, is described in Table 6-3 of the RAJ-II SAR (Section 6.1.2 of Reference 6-1). There is no intention to ship loose GNF 11x11 LUAs.

The criticality evaluation in the RAJ-II SAR (Reference 6-1) covers both a single package and a package array under NCT and HAC. The GNF 10x10 HAC package array was demonstrated to be the bounding transport configuration. Therefore, this analysis only performs criticality evaluations

M250198 Non-Proprietary Information Page 58 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis for the RAJ-II package array containing GNF 11x11 LUAs under HAC as configured in Section 6.3.1.2.2 of the RAJ-II SAR (Reference 6-1).

Table 6-2 summaries the criticality evaluation of the bounding HAC array for the RAJ-II package containing the most limiting configuration of GNF 11x11 LUAs which is the bounding GNF assembly. The effective Neutron Multiplication Factor (keff) is below the maximum keff Upper Subcritical Limit (USL) of 0.9340. This USL is described in Section 6.10 of the RAJ-II SAR (Reference 6-1).

Table 6 Criticality Evaluation Summary for GNF 11x11 LUAs Case Maximum keff Maximum keff + 2 keff + 2 to USL 3x1x3 HAC Package Array Containing GNF 11x11 LUAs 0.89650 0.00028 0.89706

-0.03694 A comparison between the nominal fuel parameters and worst case fuel parameters for GNF 11x11 LUAs used in the criticality evaluation is provided in Table 6-3.

Table 6 Nominal vs. Worst Case Fuel Parameters for the GNF 11x11 LUA Case Fuel Rod Pitch (cm)

Cladding OD (cm)

Cladding ID (cm)

Pellet OD (cm)

Pellet Theoretical Density Nominal

((

< 98%

Worst Case

))

98%

6.1.3 Criticality Safety Index Per 10 CFR 71.59, the CSI is defined as 50/N, where the number of undamaged packages in an array is 5N, and the number of damaged packages in an array is 2N. Table 6-4 lists the CSI.

Table 6 Summary of Criticality Safety Index for GNF 11x11 LUAs Case 2N N

CSI 3x1x3 HAC Package Array 9

4.5 11.2 Based on the analysis results in Section 6.6, it was concluded that the RAJ-II package meets the regulatory requirements for GNF 11x11 LUAs with a maximum U-235 enrichment of 5.0 wt%

without crediting gadolinia. Per guidance provided in 10 CFR 71.59, criticality safety is demonstrated for a shipment of up to eight RAJ-II packages containing GNF 11x11 LUAs under the bounding credible HAC.

M250198 Non-Proprietary Information Page 59 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.2 Fissile Material Contents GNF 11x11 LUAs are conservatively limited to Type A fissile material. The specific fissile material contents of GNF 11x11 LUAs are provided in Section 2.2. There are no additional changes to this section; thus Table 6-5 of the RAJ-II SAR (Reference 6-1) remains applicable for all fuel rods in this CSA (i.e., fuel rods with zirconium alloy).

6.3 General Considerations This analysis considers criticality evaluations for the RAJ-II package array containing the most limiting GNF 11x11 LUAs under HAC as configured in the RAJ-II SAR (Reference 6-1). For increased confidence in criticality safety, a more conservative configuration was analyzed and demonstrated to remain below the USL. This configuration combines the limiting parameters from the GNF 11x11 LUAs shown in Table 6-1 to generate a bounding GNF 11x11 assembly.

6.3.1 Model Configuration The RAJ-II package array HAC model considered in this analysis includes a 3x1x3 (2N = 9) array.

The 3x1x3 RAJ-II package array HAC model was used to demonstrate that the proposed CSI in Table 6-4 will remain below the USL.

The RAJ-II package is comprised of an IC and an OC fabricated from stainless steel. the IC is lined with Polyethylene Cushioning Foam (PCF). The fuel assembly rests against the PCF at a fixed position in each IC fuel compartment. The IC, with the encased alumina-silicate thermal insulation between the inner and outer walls, is positioned within the OC. Some of the packaging materials, such as honeycomb shock absorbers and wood, are not explicitly modeled. This is acceptable, as these materials do not provide effective neutron moderation compared to water.

Figure 6-1 is a cross-sectional illustration of the RAJ-II HAC model (similar to Figure 6-8 in the RAJ-II SAR (Reference 6-1)). A detailed description of the RAJ-II package array HAC model is provided in Section 6.3.1.2.2 of the RAJ-II SAR (Reference 6-1).

M250198 Non-Proprietary Information Page 60 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 6 RAJ-II Cross-Sectional HAC Model without Gadolinia Rods 6.3.2 Material Properties Material properties are described in further detail in Section 6.3.2 of the RAJ-II SAR (Reference 6-1). The material properties for GNF 11x11 LUAs are summarized in Section 2.2.

6.3.3 Computer Codes and Cross-Section Libraries KENO-VI with the ENDF/B-VII continuous-energy neutron cross-section library was used for this analysis (Reference 6-3). There are no changes to this section, thus Section 6.3.3 of the RAJ-II SAR (Reference 6-1) remains applicable.

M250198 Non-Proprietary Information Page 61 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.3.4 Demonstration of Maximum Reactivity Maximum reactivity for GNF 10x10 fuel assemblies was demonstrated in Section 6.3.4 in the RAJ-II SAR (Reference 6-1) through studies of the following factors on reactivity of the RAJ-II NCT and/or HAC arrays:

1)

Fuel Assembly Orientation (RAJ-II SAR Section 6.3.4.1)

2)

Fuel Assembly Gadolinia Rod Loading Pattern (RAJ-II SAR Section 6.3.4.2)

3)

Fuel Assembly Channel (RAJ-II SAR Section 6.3.4.3)

4)

Polyethylene Mass (RAJ-II SAR Section 6.3.4.4)

5)

Fuel Rod Pitch Sensitivity (RAJ-II SAR Section 6.3.4.5)

6)

Fuel Pellet Diameter Sensitivity (RAJ-II SAR Section 6.3.4.6)

7)

Fuel Rod Clad Thickness Sensitivity (RAJ-II SAR Section 6.3.4.7)

8)

Worst Case Parameter Fuel Designs (RAJ-II SAR Section 6.3.4.8)

9)

Part Length Fuel Rod (RAJ-II SAR Section 6.3.4.9)

10) Moderator Density (RAJ-II SAR Section 6.3.4.10)

11) Material Distribution Reactivity (RAJ-II SAR Section 6.3.4.11)

12) Inner Container Partial Flooding (RAJ-II SAR Section 6.3.4.12)

13) RAJ-II Package Spacing (RAJ-II SAR Section 6.3.4.13)

14) Methodology Justification for Uniform Enrichment Distribution, As-Built Part Length Rod Configurations, and Annular Wrapping of Polyethylene Packing Materials (RAJ-II SAR Section 6.3.4.14)

The following supplemental maximum reactivity studies are provided to support GNF 11x11 LUAs.

1)

Fuel Rod Pitch Sensitivity

2)

Limiting Pellet Diameter Sensitivity

3)

Fuel Rod Cladding Thickness Sensitivity Study

4)

Moderator Density

5)

Material Distribution Reactivity To ensure maximum reactivity of GNF 11x11 LUAs in the RAJ-II package, the IC fuel compartment is maintained at optimum moderator density and an alumina silicate thermal insulator surrounds the IC fuel compartment for each computational model. Additionally, there is no moderator (modeled as void) in the OC or between packages in the HAC array. These model conservatisms are further demonstrated in Section 6.3.4.10 and Section 6.3.4.11. A 30.48 cm thick water reflector surrounds all sides of the HAC package array.

The most limiting RAJ-II package array HAC model parameters used for GNF 11x11 LUAs are summarized in Table 6-5.

M250198 Non-Proprietary Information Page 62 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 6 Limiting HAC Model Parameters for RAJ-II Package Array Containing the Bounding Fuel Assembly Parameter Unit Value or Assumption Reference Max U-235 Pellet Enrichment wt%

5.0 Table 6-1 Limiting Lattice Enrichment Zone with Gadolinia-Urania (Gd2O3-UO2) wt%

5.0 wt% U-235 without Gd2O3-UO2 rods Section 6.3.4.2 UO2 Density g/cm3 10.7408 (98%

theoretical density)

Fuel Pellet OD cm

((

Section 6.3.4.6 Fuel Rod OD cm Section 6.3.4.7 Cladding Thickness cm Section 6.3.4.7 Fuel Rod Pitch cm

))

Section 6.3.4.5 Fuel Channel Thickness cm Unchanneled IC Dimensions (Length x Width x Height) cm 459.06 x 45.88 x 28.05 Figure 6-7 of RAJ-II SAR OC Dimensions (Length x Width x Height) cm 502.03 x 71.93 x 61.75 Figure 6-6 of RAJ-II SAR PCF Thickness cm 0.0 (Optimal)

Section 6.3.4.11 Reflector cm 30.48 (all sides)

Section 6.3.1.2.2 of RAJ-II SAR Fuel Bundle Orientation Centralized Section 6.3.4.1 of RAJ-II SAR Maximum Polyethylene per Assembly kg 10.2 Table 6-1 of RAJ-II SAR Package Array 3x1x3 (2N=9)

Section 6.6.2

M250198 Non-Proprietary Information Page 63 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.3.4.1 Fuel Assembly Orientation Study Section 6.3.4.1 of the RAJ-II SAR (Reference 6-1) demonstrates that the most reactive orientation of GNF BWR fuel assemblies contained in the RAJ-II package are centered within the fuel compartment. There is no fundamental difference in fuel design for GNF 11x11 LUAs compared to those investigated in Section 6.3.4.1 of the RAJ-II SAR (Reference 6-1). Therefore, GNF 11x11 LUAs are centered within the fuel compartment for all criticality evaluations. There are no changes to the fuel assembly orientation of the RAJ-II package resulting from the addition of GNF 11x11 LUAs. Thus, Section 6.3.4.1 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.2 Fuel Assembly Gadolinia Rod Study (2N=9)

The limiting RAJ-II package configuration (2N=9) conservatively does not credit Gd2O3-UO2 rods. The limiting fuel assembly configuration used in this analysis is assumed to conservatively bound all GNF 11x11 LUAs.

6.3.4.3 Fuel Assembly Channel Study GNF 11x11 LUAs are intended to be shipped unchanneled; therefore, the fuel assembly channel study was not performed in this CSA. There are no changes to the fuel assembly channel study due to the addition of GNF 11x11 LUAs. Therefore, Section 6.3.4.3 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.4 Polyethylene Mass Study A polyethylene mass study was not performed in this CSA. The limiting polyethylene mass for GNF 10x10 fuel from Table 6-1 of the RAJ-II SAR (Reference 6-1) is used for the GNF 11x11 LUAs and is conservatively modeled as a coating around the fuel rod cladding as described in Section 6.3.4.4 of the RAJ-II SAR (Reference 6-1). There are no changes to the polyethylene mass study due to the addition of GNF 11x11 LUAs. Therefore, Section 6.3.4.4 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.5 Fuel Rod Pitch Sensitivity Study (2N=9)

A fuel rod-to-rod pitch sensitivity study was conducted for GNF 11x11 LUAs with nominal fuel parameters in the HAC package array configuration (2N=9) consistent with Section 6.3.4.5 of the RAJ-II SAR (Reference 6-1). ((

)) The maximum fuel rod pitch in the study is ((

)) (provided in Table 6-5) to highlight a broad range of keff versus pitch values. The lattice-expanded fuel rod pitch is governed by a bounding mechanical and structural calculation that conservatively simulates a physical drop test of an RAJ-II package. The results of the calculation are provided in Section 2.7.1.1. These results demonstrate that the maximum credible fuel rod pitch expansion is (( )) of the nominal value ((( ))), yielding the value provided in Table 6-5 ((( ))).

M250198 Non-Proprietary Information Page 64 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis The fuel rod pitch sensitivity study results are provided in Table 6-6 and plotted in Figure 6-2.

These results demonstrate an increase in keff as a function of increasing fuel rod pitch. When the fuel rod pitch expands to a certain point, the PCF thickness must decrease to account for the pitch increase. This causes a double positive reactivity effect (( )), which is responsible for the non-linear nature of the curve highlighted in Figure 6-2. The effect PCF thickness has on reactivity is further assessed in Section 6.3.4.11.

Table 6 Fuel Rod Pitch at Optimal Moderation (2N=9)

Lattice Pitch (cm)

PCF Thickness (cm) keff keff +2

((

))

M250198 Non-Proprietary Information Page 65 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis

((

))

Figure 6 RAJ-II GNF 11x11 LUA Fuel Rod Pitch Sensitivity Study These results demonstrate that utilizing the lattice-expanded fuel rod pitch of (( )) is bounding and can be used for the limiting HAC array configuration (2N=9) of GNF 11x11 LUAs.

6.3.4.6 Fuel Pellet Diameter Sensitivity Study (2N=9)

Similarly to Section 6.3.4.6 of the RAJ-II SAR (Reference 6-1), a fuel pellet diameter sensitivity study was conducted for GNF 11x11 LUAs at the optimal fuel rod pitch from Table 6-5. The minimum fuel pellet diameter in this study is ((

)). The results for the fuel pellet diameter sensitivity study are provided in Table 6-7 and plotted in Figure 6-3. The results demonstrate a linear trend of increase in keff with respect to increase in fuel pellet OD. For conservatism, the maximum fuel pellet OD of

(( )) was used for the GNF 11x11 LUAs.

M250198 Non-Proprietary Information Page 66 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 6 Fuel Pellet Outer Diameter Sensitivity Study Results (2N=9)

Fuel Pellet Outer Diameter (cm) keff keff +2

((

))

((

))

Figure 6 RAJ-II GNF 11x11 LUA Fuel Pellet Outer Diameter Sensitivity Study

M250198 Non-Proprietary Information Page 67 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.3.4.7 Fuel Rod Clad Thickness Sensitivity Study (2N=9)

Similar to Section 6.3.4.7 of the RAJ-II SAR (Reference 6-1), a fuel cladding thickness study was conducted for GNF 11x11 LUAs at optimal fuel rod pitch and with a fuel pellet diameter from Table 6-5. For these studies, the ID of the cladding was held constant while the OD of the cladding was modified. The cladding material chosen for the fuel rod thickness evaluation is zirconium.

The cladding barrier is incorporated into the total cladding thickness.

For this CSA, the ratio of the limiting cladding thickness for GNF 10x10 fuels provided in Table 6-4 of the RAJ-II SAR (Reference 6-1) over the nominal cladding thickness of GNF 10x10 fuels provided in Table 6-4 of the RAJ-II SAR (Reference 6-1) was used as a basis to determine the limiting cladding thickness value for GNF 11x11 fuels. The nominal cladding thickness for GNF 11x11 fuels ((( ))) was scaled by the GNF 10x10 cladding decrease basis ratio to yield a minimum conservative GNF 11x11 cladding thickness value of (( ))

(Table 6-5). An additional evaluation was performed using the minimum cladding thickness to incorporate the cladding ID tolerance.

The results for the cladding thickness sensitivity study are provided in Table 6-8 and Figure 6-4.

These results demonstrate a linear decrease in keff with respect to an increase in cladding thickness.

Based on these results, it was deemed conservative to utilize the minimum cladding thickness value of (( )) for the GNF 11x11 LUA. This value was incorporated to determine the limiting cladding ID and OD provided in Table 6-5.

Table 6 Fuel Cladding Thickness Sensitivity Study Results (2N=9)

Fuel Cladding Thickness (cm) keff keff +2

((

M250198 Non-Proprietary Information Page 68 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Fuel Cladding Thickness (cm) keff keff +2

))

Note: (( ))

((

))

Figure 6 RAJ-II GNF 11x11 LUA Fuel Cladding Thickness Sensitivity Study 6.3.4.8 Worst Case Parameter Fuel Designs The previous evaluations have varied single fuel design parameters and assessed their effect on reactivity. In this CSA, multiparameter fuel design variations are not performed; the subsections below are combined with the bounding fuel design parameters to develop a limiting GNF 11x11 fuel assembly that will allow shipments of GNF 11x11 LUAs.

M250198 Non-Proprietary Information Page 69 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.3.4.9 Part Length Fuel Rod Study There is no additional part length fuel rod configurations identified for GNF 11x11 LUAs; therefore, this study was not performed. There are no changes to the part length fuel rod study resulting from the addition of GNF 11x11 LUAs. Thus, Section 6.3.4.9 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.10 Moderator Density Study Similar to Section 6.3.4.10 of the RAJ-II SAR (Reference 6-1), a moderator density study was conducted for the HAC package array configuration (2N=9) containing GNF 11x11 LUAs at optimal fuel rod pitch, pellet diameter, and cladding thickness from Table 6-5.

For the OC moderator density study, the density of the water in the OC was incremented from 0.0 g/cm3 (void) to 1.0 g/cm3. The study reveals an increase to system reactivity as a function of decreasing OC moderator density, thus confirming that the most limiting HAC package array configuration (2N=9) of GNF 11x11 LUAs should contain no moderator (void) in the OC region.

The results for this study are provided in Table 6-9 and plotted in Figure 6-5.

For the IC moderator density study, the density of the water in the IC was incremented from 0.1 g/cm3 to 1.0 g/cm3. The results demonstrate an increase in system reactivity as a function of increasing IC moderator density, confirming that the HAC package array configuration (2N=9) of GNF 11x11 LUAs should contain full-density moderator inside the IC region. Results are provided in Table 6-10 and plotted in Figure 6-6.

Table 6 Outer Container Moderator Density Sensitivity Study Results (2N=9)

Outer Container Moderator Density (g/cm3) keff keff +2 0.0 0.85378 0.00031 0.85440 0.1 0.83086 0.00026 0.83138 0.2 0.79380 0.00026 0.79432 0.3 0.77252 0.00027 0.77306 0.4 0.76360 0.00025 0.76410 0.5 0.75927 0.00027 0.75981 0.6 0.75811 0.00025 0.75861 0.7 0.75772 0.00032 0.75836 0.8 0.75825 0.00028 0.75881 0.9 0.75895 0.00027 0.75949 1.0 0.75995 0.00030 0.76055

M250198 Non-Proprietary Information Page 70 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Figure 6 RAJ-II GNF 11x11 LUA Outer Container Moderator Density Sensitivity Study Table 6 Inner Container Moderator Density Sensitivity Study Results (2N=9)

Inner Container Moderator Density (g/cm3) keff keff +2 0.1 0.51636 0.00021 0.51678 0.2 0.56651 0.00023 0.56697 0.3 0.61454 0.00025 0.61504 0.4 0.66079 0.00027 0.66133 0.5 0.70221 0.00025 0.70271 0.6 0.74085 0.00026 0.74137 0.7 0.77464 0.00026 0.77516 0.8 0.80451 0.00030 0.80511 0.9 0.83064 0.00025 0.83114 1.0 0.85378 0.00031 0.85440

M250198 Non-Proprietary Information Page 71 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Figure 6 RAJ-II GNF 11x11 LUA Inner Container Moderator Density Sensitivity Study 6.3.4.11 Material Distribution Reactivity Study (2N=9)

Similar to Section 6.3.4.11 in the RAJ-II SAR (Reference 6-1), a study was conducted to confirm the most limiting packing material distribution for RAJ-II ICs containing GNF 11x11 LUAs. The nominal material surrounding the IC fuel compartment is a thermal insulator consisting of alumina silicate, and the material lining the IC fuel compartment is PCF with nominal thickness of 1.80 cm.

The first part of the material distribution study investigates replacing the alumina silicate with full-density water and void while maintaining full-density water in the IC. The fuel was modeled with the limiting pitch, fuel pellet diameter, and fuel cladding thickness parameters provided in Table 6-5.

The results demonstrate that the presence of the alumina silicate thermal insulator yields a more reactive system compared to a water-filled or voided region within the IC. Thus, alumina silicate remains in the IC region for the remainder of this CSA. Results are provided in Table 6-11.

M250198 Non-Proprietary Information Page 72 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Table 6 RAJ-II Inner Container Thermal Insulator Region (2N=9)

Material in the IC Region keff keff +2 Void 0.83987 0.00031 0.84049 Water 0.84230 0.00027 0.84284 Alumina Silicate 0.85378 0.00031 0.85440 The second part of the material distribution study investigates the limiting PCF thickness for RAJ-II packages in the HAC array (2N=9) containing GNF 11x11 LUAs with optimal fuel parameters and moderator conditions. In the postulated fire scenario described in Section 6.3.4.11 of the RAJ-II SAR (Reference 6-1), the PCF would be susceptible to burn in a similar fashion as the polyethylene packing materials surrounding the fuel rods. The PCF may partially burn or burn away completely. To assess the effect PCF thickness has on reactivity, the PCF thickness was varied from a maximum value of 2.084 cm down to 0.0 cm.

The PCF thickness study results are provided in Table 6-12 and plotted in Figure 6-7. Note that the results for keff +2 remain relatively constant between 0.0 cm and 0.37 cm, with relative differences of only a few in that range. Due to the closeness in results in that region, an optimal PCF thickness of 0.0 cm was chosen for the GNF LUA and used throughout the remainder of the CSA.

Table 6 RAJ-II PCF Thickness Study Results (2N=9)

PCF Thickness (cm) keff keff +2 0.000 0.89650 0.00028 0.89706 0.050 0.89664 0.00024 0.89712 0.157 0.89735 0.00024 0.89783 0.264 0.89676 0.00024 0.89724 0.371 0.89653 0.00032 0.89717 0.478 0.89618 0.00026 0.89670 0.585 0.89426 0.00026 0.89478 0.692 0.89330 0.00024 0.89378 0.799 0.89109 0.00029 0.89167 0.907 0.88891 0.00027 0.88945 1.014 0.88603 0.00027 0.88657

M250198 Non-Proprietary Information Page 73 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis PCF Thickness (cm) keff keff +2 1.121 0.88369 0.00029 0.88427 1.228 0.88002 0.00029 0.88060 1.335 0.87540 0.00026 0.87592 1.442 0.87104 0.00026 0.87156 1.549 0.86651 0.00032 0.86715 1.656 0.86115 0.00026 0.86167 1.763 0.85519 0.00026 0.85571 1.870 0.84918 0.00024 0.84966 1.977 0.84346 0.00028 0.84402 2.084 0.83612 0.00024 0.83660 Figure 6 RAJ-II GNF 11x11 LUA PCF Thickness Sensitivity Study Results There are no additional changes to this section. Thus, the remainder of Section 6.3.4.11 of the RAJ-II SAR (Reference 6-1) remains applicable.

M250198 Non-Proprietary Information Page 74 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.3.4.12 Inner Container Partial Flooding Study There are no changes to the IC partial flooding resulting from the addition of GNF 11x11 LUAs.

Thus, Section 6.3.4.12 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.13 RAJ-II Package Spacing Study There are no changes to the RAJ-II package spacing resulting from the addition of GNF 11x11 LUAs. Thus, Section 6.3.4.13 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.3.4.14 Other Considerations There are no changes to this section resulting from the addition of GNF 11x11 LUAs. Thus, Section 6.3.4.14 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.4 Single Package Evaluation There are no changes to the single package evaluation in Section 6.4 of the RAJ-II SAR (Reference 6-1) resulting from the addition of GNF 11x11 LUAs. Thus, Section 6.4 of the RAJ-II SAR (Reference 6-1) remains applicable.

A single package evaluation under NCT and HAC was performed for GNF 11x11 LUAs to confirm that the HAC single package bounds the NCT single package. An additional evaluation confirms that the HAC package array (2N=9) bounds the HAC single package. A 30.48 cm thick water reflector surrounds all sides of the NCT and HAC single package. Results are provided in Table 6-13.

Table 6 NCT, HAC Single Package Versus HAC Package Array (2N=9)

Package Configuration keff keff +2 NCT Single Package 0.67386 0.00030 0.67446 HAC Single Package 0.78289 0.00031 0.78351 HAC Package Array (2N=9) 0.89650 0.00028 0.89706 6.5 Evaluation of Package Arrays Under NCT The evaluation of RAJ-II package arrays under NCT for GNF 11x11 LUAs was not performed.

The NCT single package results are bounded by the HAC single package results (see Table 6-13);

therefore, it was concluded that the HAC package array bounds the NCT package array. The physical reduction in size and optimal moderator conditions for packages in HAC yields a more reactive system compared to NCT. It was therefore concluded that if the criticality safety of the RAJ-II package was demonstrated under HAC, it is also demonstrated under NCT. Section 6.5 of the RAJ-II SAR (Reference 6-1) remains applicable.

M250198 Non-Proprietary Information Page 75 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.6 Package Arrays Under HAC (2N=9) 6.6.1 Configuration The optimal HAC package array model was used to demonstrate criticality safety of a 3x1x3 (2N=9) array of RAJ-II packages with the GNF 11x11 LUA bounding fuel design at an average enrichment of 5.0 wt% U-235 without Gd2O3-UO2 fuel rods (see Table 6-5). This section investigates two moderator density studies to confirm the most reactive configuration. In the first moderator study, void was modeled in the OC while the moderator density was uniformly varied inside the IC. In the second study, full-density moderator was modeled in the IC while the moderator density was uniformly varied in the OC. The PCF thickness inside the IC fuel compartment for both studies was modeled at the optimal value of 0.0 cm (see Section 6.3.4.11).

6.6.2 Results The results of the RAJ-II HAC package array (2N=3x1x3=9) IC moderator density calculations are shown in Table 6-14 and Figure 6-8. The results demonstrate that reactivity increases with respect to an increase in IC moderator density, thus confirming that the most reactive configuration contains full-density moderator within the IC fuel compartment.

Table 6 Optimal RAJ-II HAC Array - Inner Container Moderator Study IC Moderator Density (g/cm3) keff keff +2 0.0 0.44133 0.00022 0.44177 0.1 0.51527 0.00021 0.51569 0.2 0.59250 0.00025 0.59300 0.3 0.66145 0.00025 0.66195 0.4 0.72000 0.00030 0.72060 0.5 0.76807 0.00026 0.76859 0.6 0.80658 0.00028 0.80714 0.7 0.83768 0.00025 0.83818 0.8 0.86155 0.00025 0.86205 0.9 0.88105 0.00028 0.88161 1.0 0.89650 0.00028 0.89706

M250198 Non-Proprietary Information Page 76 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis Figure 6 RAJ-II Optimal HAC Inner Container Moderator Density Sensitivity Study The results of the RAJ-II HAC package array (2N=3x1x3=9) OC moderator density calculations are shown in Table 6-15 and Figure 6-9. The results demonstrate that the reactivity increases with respect to a moderator density decrease, thus confirming that a void in the OC region is the most reactive configuration.

Table 6 Optimal RAJ-II HAC Array - Outer Container Moderator Study OC Moderator Density (g/cm3) keff keff +2 0.0 0.89650 0.00028 0.89706 0.1 0.86338 0.00025 0.86388 0.2 0.84167 0.00026 0.84219 0.3 0.83148 0.00043 0.83234 0.4 0.82662 0.00027 0.82716 0.5 0.82439 0.00030 0.82499 0.6 0.82347 0.00026 0.82399

M250198 Non-Proprietary Information Page 77 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis OC Moderator Density (g/cm3) keff keff +2 0.7 0.82328 0.00030 0.82388 0.8 0.82320 0.00027 0.82374 0.9 0.82363 0.00026 0.82415 1.0 0.82376 0.00025 0.82426 Figure 6 RAJ-II Optimal HAC Outer Container Moderator Density Sensitivity Study The results confirm that a void in the OC and full moderator density in the fuel compartment of the IC yields the most reactive configuration. The maximum keff + 2 for the HAC package array with these conditions is provided in Table 6-2 and is below the USL of 0.9340. Therefore, criticality safety of the RAJ-II package array is demonstrated under HAC.

6.6.2.1 Pu-239 Effect on Reactivity for the RAJ-II Package Array HAC GNF 11x11 LUAs are administratively limited to Type A material content. Therefore, plutonium shipments within the GNF 11x11 LUAs are not allowed. No additional changes are required for this section. Thus, Section 6.6.2.1 of the RAJ-II SAR (Reference 6-1) remains applicable.

M250198 Non-Proprietary Information Page 78 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6.7 Fuel Rod Transportation in the RAJ-II There is no intention to ship loose GNF 11x11 LUAs. Therefore, Section 6.7 and the applicable subsections of the RAJ-II SAR (Reference 6-1) are not applicable.

6.8 Fissile Material Packages for Air Transport This package is not intended for the air transport of fissile material.

6.9 Conclusion Based on the calculations that have been documented, the RAJ-II package is qualified to transport GNF 11x11 UO2 LUAs in accordance with the criticality safety requirements set forth in 10 CFR 71. The following conclusions are drawn from this CSA:

1)

GNF 11x11 LUAs will be shipped unchanneled.

2)

GNF 11x11 LUAs are conservatively limited to Type A material.

3)

GNF 11x11 LUAs are restricted to a maximum enrichment of 5.0 wt% U-235.

4)

GNF 11x11 LUAs are not required to have gadolinia rods.

5)

GNF 11x11 LUAs have a CSI of 11.2.

6)

GNF 11x11 LUAs may contain additive fuel as previously approved (Reference 6-2).

6.10 Benchmark Evaluations 6.10.1 SCALE 4.4a and GEMER SCALE 4.4a and GEMER were not used for this CSA; thus, Section 6.10.1 of the RAJ-II SAR (Reference 6-1) is not applicable.

6.10.2 KENO-VI The results reported in this letter authorization request were performed using KENO-VI, which is part of the SCALE 6.1 analysis package (Reference 6-3), with the continuous-energy ENDF/B-VII cross-section library. Critical experiments were selected to represent the materials and geometry of the package. There are no changes to this section; thus, Section 6.10.2 of the RAJ-II SAR (Reference 6-1) remains applicable.

6.11 Appendix Representative KENO-VI inputs are provided in Section 6.11 of the RAJ-II SAR (Reference 6-1).

6.12 References 6-1 Global Nuclear Fuel, RAJ-II Safety Analysis Report, NEDE-33869P, Revision 11, September 2022.

6-2 Letter, Yoira Diaz-Sanabria (NRC) to Brian R. Moore (GNF), Letter Authorization to Use the Model No. RAJ-II Package with an Increased Maximum Authorized Fuel Pellet Silicon Concentration, September 6, 2024. (ADAMS Accession No. ML24247A220)

M250198 Non-Proprietary Information Page 79 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 6-3 Oak Ridge National Laboratory, Scale: A Comprehensive Modeling and Simulation Suite for Nuclear Safety Analysis and Design, ORNL/TM-2005/39 Version 6.1, 2011.

M250198 Non-Proprietary Information Page 80 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 7.0 PACKAGE OPERATIONS There are no changes to this section with the introduction of new contents; thus, Chapter 7.0 of the GNF RAJ-II SAR, Docket Number 71-9309, Revision 11, as amended, and approving RAJ-II CoC Number 9309 Revision 14 remain applicable. The general instructions in the SAR include those for loading, unloading, and preparation of the empty container for transport.

M250198 Non-Proprietary Information Page 81 of 81 11x11 Fuel RAJ-II Letter Authorization Request and Technical Basis 8.0 ACCEPTANCE TESTS AND MAINTENANCE PROGRAM There are no changes to this section with the introduction of new contents; thus, Chapter 8.0 of the GNF RAJ-II SAR, Docket Number 71-9309, Revision 11, as amended, and approving RAJ-II CoC Number 9309 Revision 14 remain applicable. Acceptance tests and maintenance for this request are unchanged for this letter authorization request.