ML15282A192
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ATTACHMENT 25 ANP-3386NP, Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies (Non-Proprietary)
ANP-3386NP Revision 1 Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU)
ATRIUM 10XM Fuel Assemblies Licensing Report August 2015 AREVA Inc.
(c) 2015 AREVA Inc.
ANP-3386NP Revision 1 Copyright © 2015 AREVA Inc.
All Rights Reserved
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page i Nature of Changes Item Revision Number Section(s) or Page(s)
Description and Justification
- 1.
0 All This is a new document.
- 2.
1 All Updated proprietary bracketing for consistency.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page ii Contents 1.0 Introduction..................................................................................................................... 1 2.0 Design Description.......................................................................................................... 3 2.1 Fuel Assembly..................................................................................................... 3 2.1.1 Spacer Grid............................................................................................ 3 2.1.2 Water Channel....................................................................................... 4 2.1.3 Lower Tie Plate...................................................................................... 4 2.1.4 Upper Tie Plate and Connecting Hardware............................................ 5 2.1.5 Fuel Rods.............................................................................................. 5 2.2 Fuel Channel and Components............................................................................ 6 3.0 Fuel Design Evaluation.................................................................................................. 10 3.1 Objectives.......................................................................................................... 10 3.2 Fuel Rod Evaluation........................................................................................... 10 3.3 Fuel System Evaluation..................................................................................... 11 3.3.1 Stress, Strain, or Loading Limits on Assembly Components......................................................................................... 11 3.3.2 Fatigue................................................................................................. 12 3.3.3 Fretting Wear....................................................................................... 12 3.3.4 Oxidation, Hydriding, and Crud Buildup................................................ 12 3.3.5 Rod Bow.............................................................................................. 13 3.3.6 Axial Irradiation Growth........................................................................ 13 3.3.7 Rod Internal Pressure.......................................................................... 14 3.3.8 Assembly Lift-off.................................................................................. 14 3.3.9 Fuel Assembly Handling....................................................................... 15 3.3.10 Miscellaneous Component Criteria....................................................... 15 3.3.10.1 Compression Spring Forces................................................. 15 3.3.10.2 LTP Seal Spring................................................................... 16 3.4 Fuel Coolability.................................................................................................. 16 3.4.1 Cladding Embrittlement........................................................................ 16 3.4.2 Violent Expulsion of Fuel...................................................................... 16 3.4.3 Fuel Ballooning.................................................................................... 16 3.4.4 Structural Deformations....................................................................... 16 3.5 Fuel Channel and Fastener................................................................................ 18 3.5.1 Design Criteria for Normal Operation................................................... 18 3.5.2 Design Criteria for Accident Conditions................................................ 19 4.0 Mechanical Testing........................................................................................................ 26 4.1 Fuel Assembly Axial Load Test.......................................................................... 26 4.2 Spacer Grid Lateral Impact Strength Test.......................................................... 26 4.3 Tie Plate Strength Tests..................................................................................... 27 4.4 Debris Filter Efficiency Test............................................................................... 28 4.5 Fuel Assembly Fretting Test.............................................................................. 28 4.6 Fuel Assembly Static Lateral Deflection Test..................................................... 28 4.7 Fuel Assembly Lateral Vibration Tests............................................................... 28 4.8 Fuel Assembly Impact Tests.............................................................................. 29 AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page iii 5.0 References.................................................................................................................... 30 Appendix A Illustrations...................................................................................................... 31 Tables Table 2-1 Fuel Assembly and Component Description............................................................... 7 Table 2-2 Fuel Channel and Fastener Description..................................................................... 9 Table 3-1 Results for ATRIUM 10XM Fuel Assembly............................................................... 20 Table 3-2 Results for Advanced Fuel Channel......................................................................... 23 Table 3-3 Results for Channel Fastener................................................................................... 25 Figures Figure A-1 ATRIUM 10XM Fuel Assembly (not to scale).......................................................... 32 Figure A-2 UTP with Locking Hardware................................................................................... 33 Figure A-3 Lower Tie Plate....................................................................................................... 34 Figure A-4 ATRIUM 10XM ULTRAFLOW Spacer Grid............................................................. 35 Figure A-5 Full and Part-Length Fuel Rods.............................................................................. 36 Figure A-6 Advanced Fuel Channel......................................................................................... 37 Figure A-7 Fuel Channel Fastener Assembly........................................................................... 38 This document contains a total of 44 pages.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page iv Nomenclature Acronym Definition AFC Advanced Fuel Channel AOO Anticipated Operational Occurrences ASME American Society of Mechanical Engineers B&PV Boiler and Pressure Vessel BOL Beginning of Life BWR Boiling Water Reactor CHF Critical Heat Flux EOL End of Life HALC Harmonized Advanced Load Chain LOCA Loss-of-Coolant Accident LTP Lower Tie Plate MWd/kgU Megawatt-days per kilogram of Uranium NRC U. S. Nuclear Regulatory Commission PLFR Part-Length Fuel Rods psi Pounds per square inch Sm Design stress intensity SRA Stress Relief Annealed SRP Standard Review Plan Su Ultimate stress Sy Yield stress UTP Upper Tie Plate AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 1 1.0 Introduction The purpose of this report is to show that the AREVA Inc. (AREVA) fuel mechanical design criteria are satisfied at Browns Ferry EPU conditions (120 percent of original licensed thermal power (OLTP)). This report provides a design description, mechanical design criteria, fuel structural analysis results, and test results for the ATRIUM'* 10XM fuel assembly and 100/75 Advanced Fuel Channel (AFC) designs supplied by AREVA Inc. (AREVA) for use at Browns Ferry Units 1, 2 and 3.
The scope of this report is limited to an evaluation of the structural design of the fuel assembly and fuel channel. The fuel assembly structural design evaluation is not cycle-specific so this report is intended to be referenced for each cycle where the fuel design is in use. Minor changes to the fuel design and cycle-specific input parameters will be dispositioned for future reloads. AREVA will confirm the continued applicability of this report prior to delivery of each subsequent reload of ATRIUM 10XM fuel at Browns Ferry Units 1, 2 and 3.
Many of the structural analyses of the fuel assembly are done on a generic basis. However, the increase in core power for EPU is also associated with an increase in core pressure drop which does have an effect on some mechanical analyses. This increase in pressure specifically affects the fuel assembly liftoff analyses and the calculated stress and deformation of the fuel channel and water channel. These analyses were revisited and shown to maintain design margin.
The fuel assembly design was evaluated according to the AREVA boiling water reactor (BWR) generic mechanical design criteria (Reference 1). The fuel channel design was evaluated to the criteria given in the fuel channel topical report (Reference 2). The generic design criteria have been approved by the U.S. Nuclear Regulatory Commission (NRC) and the criteria are applicable to the subject fuel assembly and channel design.
Mechanical analyses have been performed using NRC-approved design analysis methodology (References 1, 2, 3, and 4). The methodology permits maximum licensed assembly and fuel channel exposures of [
] (Reference 3). Documentation of compliance with the ATRIUM is a trademark of AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 2 generic design criteria using approved methods demonstrates licensing approval of the fuel design.
The fuel assembly and channel meets all mechanical compatibility requirements for use in Browns Ferry Units 1, 2 and 3. This includes compatibility with both co-resident fuel and the reactor core internals.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 3 2.0 Design Description This report documents the structural evaluation of the ATRIUM 10XM fuel assembly and fuel channel described below. Reload-specific design information is available in the design package provided by AREVA for each reload delivery.
2.1 Fuel Assembly The ATRIUM 10XM fuel assembly consists of a lower tie plate (LTP) and upper tie plate (UTP),
91 fuel rods, [
] spacer grids, a central water channel with [
],
and miscellaneous assembly hardware. Of the 91 fuel rods, [
] are PLFRs. The structural members of the fuel assembly include the tie plates, spacer grids, water channel, and connecting hardware. [
].
The fuel assembly is accompanied by a fuel channel, as described later in this section.
Table 2-1 lists the main fuel assembly attributes, and an illustration of the fuel bundle assembly is provided in Appendix A.
2.1.1 Spacer Grid The spacer grid is a [
] version of the ULTRAFLOW' design. [
].
ULTRAFLOW is a trademark of AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 4 Table 2-1 lists the main spacer grid attributes, and an illustration of the spacer grid is provided in Appendix A.
2.1.2 Water Channel
[
].
Table 2-1 lists the main water channel attributes and Appendix A provides an illustration of a section of the water channel.
2.1.3 Lower Tie Plate The diffuser box of the LTP [
].
Appendix A provides a generic illustration of the LTP.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 5 2.1.4 Upper Tie Plate and Connecting Hardware
[
].
Appendix A provides an illustration of the UTP and locking components.
2.1.5 Fuel Rods
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 6
[
].
Table 2-1 lists the main fuel rod attributes, and Appendix A provides an illustration of the full length and part length fuel rods.
2.2 Fuel Channel and Components
[
].
Table 2-2 lists the fuel channel component attributes. The fuel channel and fuel channel fastener are depicted in Appendix A.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 7 Table 2-1 Fuel Assembly and Component Description
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 8 Table 2-1 Fuel Assembly and Component Description (Continued)
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 9 Table 2-2 Fuel Channel and Fastener Description
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 10 3.0 Fuel Design Evaluation A summary of the mechanical methodology and results from the structural design evaluations is provided in this section. Results from the mechanical design evaluation demonstrate that the design satisfies the mechanical criteria to the analyzed exposure limit.
3.1 Objectives The objectives of designing fuel assemblies (systems) to specific criteria are to provide assurance that:
The fuel assembly (system) shall not fail as a result of normal operation and anticipated operational occurrences (AOOs). The fuel assembly (system) dimensions shall be designed to remain within operational tolerances, and the functional capabilities of the fuels shall be established to either meet or exceed those assumed in the safety analysis.
Fuel assembly (system) damage shall never prevent control rod insertion when it is required.
The number of fuel rod failures shall be conservatively estimated for postulated accidents.
Fuel coolability shall always be maintained.
The mechanical design of fuel assemblies shall be compatible with co-resident fuel and the reactor core internals.
Fuel assemblies shall be designed to withstand the loads from handling and shipping.
The first four objectives are those cited in the Standard Review Plan (SRP). The latter two objectives are to assure the structural integrity of the fuel and the compatibility with the existing reload fuel. To satisfy these objectives, the criteria are applied to the fuel rod and the fuel assembly (system) designs. Specific component criteria are also necessary to assure compliance. The criteria established to meet these objectives include those given in Chapter 4.2 of the SRP.
3.2 Fuel Rod Evaluation The mechanical design report documents the fuel structural analyses only. The fuel rod evaluation is performed each cycle and is documented in the Browns Ferry cycle specific fuel rod thermal-mechanical report.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 11 3.3 Fuel System Evaluation The detailed fuel system design evaluation is performed to ensure the structural integrity of the design under normal operation, AOO, faulted conditions, handling operations, and shipping.
The analysis methods are based on fundamental mechanical engineering techniquesoften employing finite element analysis, prototype testing, and correlations based on in-reactor performance data. Summaries of the major assessment topics are described in the sections that follow.
3.3.1 Stress, Strain, or Loading Limits on Assembly Components The structural integrity of the fuel assemblies is assured by setting design limits on stresses and deformations due to various handling, operational, and accident or faulted loads. AREVA uses Section Ill of the ASME B&PV Code as a guide to establish acceptable stress, deformation, and load limits for standard assembly components. These limits are applied to the design and evaluation of the UTP, LTP, spacer grids, springs, and load chain components, as applicable.
The fuel assembly structural component criteria under faulted conditions are based on Appendix F of the ASME B&PV Code Section III with some criteria derived from component tests.
All significant loads experienced during normal operation, AOOs, and under faulted conditions are evaluated to confirm the structural integrity of the fuel assembly components. Outside of faulted conditions, most structural components are under the most limiting loading conditions during fuel handling. See Section 3.3.9 for a discussion of fuel handling loads and Section 3.4.4 for the structural evaluation of faulted conditions. Although normal operation and AOO loads are often not limiting for structural components, a stress evaluation may be performed to confirm the design margin and to establish a baseline for adding accident loads. The stress calculations use conventional, open-literature equations. A general-purpose, finite element stress analysis code, such as ANSYS, may be used to calculate component stresses.
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 12
[
].
See Table 3-1 for results from the component strength evaluations.
3.3.2 Fatigue Fatigue of structural components is generally [
].
3.3.3 Fretting Wear Fuel rod failures due to grid-to-rod fretting shall not occur. [
].
Fretting wear is evaluated by testing, as described in Section 4.5. The testing is conducted by
[
]. The inspection measurements for wear are documented. [
].
[
] and has operated successfully without incidence of grid-to-rod fretting in more than 20,000 fuel assemblies.
3.3.4 Oxidation, Hydriding, and Crud Buildup Because of the low amount of corrosion on fuel assembly structural components, [
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 13
[
].
3.3.5 Rod Bow Differential expansion between the fuel rods and cage structure, and lateral thermal and flux gradients can lead to lateral creep bow of the rods in the spans between spacer grids. This lateral creep bow alters the pitch between the rods and may affect the peaking and local heat transfer. The AREVA design criterion for fuel rod bowing is that [
].
Rod bow is calculated using the approved model described in Reference 4. [
]. The predicted rod-to-rod gap closure due to bow is assessed for impact on thermal margins.
3.3.6 Axial Irradiation Growth Fuel assembly components, including the fuel channel, shall maintain clearances and engagements, as appropriate, throughout the design life. Three specific growth calculations are considered for the ATRIUM 10XM design:
Minimum fuel rod clearance between the LTP and UTP Minimum engagement of the fuel channel with the LTP seal spring External interfaces (e.g., channel fastener springs)
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 14 Rod growth, assembly growth, and fuel channel growth are calculated using correlations derived from post-irradiation data. The evaluation of initial engagements and clearances accounts for the combination of fabrication tolerances on individual component dimensions.
The SRA fuel rod growth correlation was established from [
]. Assembly growth is dictated by the water channel growth. The growth of the water channel and the fuel channel is based on [
]. These data and the resulting growth correlations are described in Reference 3. The upper and lower [
], as appropriate, are used to obtain EOL growth values.
The minimum EOL rod growth clearance and EOL fuel channel engagement with the seal spring are listed in Table 3-1. The channel fastener spring axial compatibility is reported in Table 3-3.
3.3.7 Rod Internal Pressure This is addressed in the Browns Ferry fuel rod thermal-mechanical report.
3.3.8 Assembly Lift-off Fuel assembly lift-off is evaluated under both normal operating conditions (including AOOs) and under faulted conditions. The fuel shall not levitate under normal operating or AOO conditions.
Under postulated accident conditions, the fuel shall not become disengaged from the fuel support. These criteria assure control blade insertion is not impaired.
For normal operating conditions, the net axial force acting on the fuel assembly is calculated by adding the loads from gravity, hydraulic resistance from coolant flow, difference in fluid flow entrance and exit momentum, and buoyancy. The calculated net force is confirmed to be in the downward direction, indicating no assembly lift-off. Maximum hot channel conditions are used in the calculation because the greater two-phase flow losses produce a higher uplift force.
Mixed core conditions for assembly lift-off are considered on a cycle-specific basis, as determined by the plant and other fuel types. Analyses to date indicate a large margin to assembly lift-off under normal operating conditions. Therefore, fuel lift-off in BWRs under normal operating conditions is considered to be a small concern.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 15 For faulted conditions, [
]. The uplift is limited to be less than the axial engagement such that the fuel assembly neither becomes laterally displaced nor blocks insertion of the control blade.
3.3.9 Fuel Assembly Handling The fuel assembly shall withstand, without permanent deformation, all normal axial loads from shipping and fuel handling operations. Analysis or testing shall show that the fuel is capable of
[
].
The fuel assembly structural components are assessed for axial fuel handling loads by testing.
To demonstrate compliance with the criteria, the test is performed by loading a test assembly to an axial tensile force greater than [
]. An acceptable test shows no yielding after loading. The testing is described further in Section 4.1.
There are also handling requirements for the fuel rod plenum spring which are addressed in the Browns Ferry fuel rod thermal-mechanical report.
3.3.10 Miscellaneous Component Criteria 3.3.10.1 Compression Spring Forces The ATRIUM 10XM has a single large compression spring mounted on the central water channel. The compression spring serves the same function as previous designs by providing support for the UTP and fuel channel. The spring force is calculated based on the deflection and specified spring force requirements. Irradiation-induced relaxation is taken into account for EOL conditions. The minimum compression spring force at EOL is shown to be greater than the combined weight of the UTP and fuel channel (including channel fastener hardware). Since the compression spring does not interact with the fuel rods, no consideration is required for fuel rod buckling loads.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 16 3.3.10.2 LTP Seal Spring The LTP seal spring shall limit the bypass coolant leakage rate between the LTP and fuel channel. The seal spring shall accommodate expected channel deformation while remaining in contact with the fuel channel. Also, the seal spring shall have adequate corrosion resistance and be able to withstand the operating stresses without yielding.
Flow testing is used to confirm acceptable bypass flow characteristics. The seal spring is designed with adequate deflection to accommodate the maximum expected channel bulge while maintaining acceptable bypass flow. [
] is selected as the material because of its high strength at elevated temperature and its excellent corrosion resistance. Seal spring stresses are analyzed using a finite element method.
3.4 Fuel Coolability For accidents in which severe fuel damage might occur, core coolability and the capability to insert control blades are essential. Chapter 4.2 of the SRP provides several specific areas important to fuel coolability, as discussed below.
3.4.1 Cladding Embrittlement This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.2 Violent Expulsion of Fuel This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.3 Fuel Ballooning This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.4 Structural Deformations The methodology for analyzing the fuel under the influence of seismic/LOCA analysis loads is described in References 2, 6 and 7. Evaluations performed for the fuel under combined seismic/LOCA loadings include mechanical fracturing of the fuel rod cladding, assembly structural integrity, and fuel assembly liftoff. Restricting fuel uplift and limiting fuel channel deformation under accident conditions permit insertion of the control blades.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 17 The testing and analyses have shown the dynamic response of the ATRIUM 10XM design to be very similar to the ATRIUM-10. The ATRIUM-10 fuel assembly has been evaluated for integrity during external loading by testing and analysis. Testing is done to obtain the dynamic characteristics of the fuel assembly and spacer grids. The stiffnesses, natural frequencies and damping values derived from the tests are used as inputs for dynamic mechanical models of the fuel assembly and fuel channel. Tests are done with and without a fuel channel. In addition, the dynamic models are compared to the test results to ensure an accurate characterization of the fuel. See Section 4.0 for descriptions of testing.
[
].
Similar to the ATRIUM-10, the ATRIUM 10XM assembly will be delivered to Browns Ferry with the AFC design. Given that the [
] is the limiting component, the fuel assembly component loads and stresses calculated for the ATRIUM-10 will remain applicable to the ATRIUM 10XM. Table 3-3 lists the margins for fuel assembly components at the maximum acceleration allowed for the channel design. Component load and stress limits are derived using the ASME B&PV Code,Section III, Division 1, Appendix F, and SRP Section 4.2, Appendix A. Specified tensile properties or testing are used to establish the limits.
In general, the dynamic responses of the ATRIUM 10XM and the ATRIUM-10 are very similar to other BWR fuel designs that have the same basic channel configuration and weight. This includes the previously analyzed GNF fuel at Browns Ferry. In addition, the original or revised seismic/LOCA reactor pressure vessel analyses performed to determine maximum core accelerations, deflections, and loads will apply to the ATRIUM 10XM because of the dynamic similarity with past designs. The dynamic response of the channeled ATRIUM 10XM fuel assembly is primarily dependent on the fuel channel stiffness and the fuel assembly mass.
Because the fuel assembly weight and channel stiffness do not vary significantly from prior AREVA fuel designs (or other co-resident fuel types), the maximum loads and deflections for the ATRIUM 10XM fuel assembly will be essentially unchanged from before.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 18 Assembly liftoff under accident conditions is described in Section 3.3.8.
3.5 Fuel Channel and Fastener The fuel channel and fastener design criteria are summarized below, and evaluation results are summarized in Table 3-2 and Table 3-3. The analysis methods are described in detail in Reference 2.
3.5.1 Design Criteria for Normal Operation Steady-State Stress Limits. The stress limits during normal operation are obtained from the ASME B&PV Code,Section III, Division 1, Subsection NG for Service Level A. The calculated stress intensities are due to the differential pressure across the channel wall. The pressure loading includes the normal operating pressure plus the increase during AOO. The unirradiated properties of the fuel channel material are used since the yield and ultimate tensile strength increase during irradiation (Reference 8).
As an alternative to the elastic analysis stress intensity limits, a plastic analysis may be performed as permitted by paragraph NB-3228.3 of the ASME B&PV Code.
In the case of AOOs, the amount of bulging is limited to that value which will permit control blade movement. During normal operation, any significant permanent deformation due to yielding is precluded by restricting the maximum stresses at the inner and outer faces of the channel to be less than the yield strength.
Fuel Channel Fatigue. Cyclic changes in power and flow during operation impose a duty loading on the fuel channel. [
].
Corrosion and Hydrogen Concentration. Corrosion reduces the material thickness and results in less load-carrying capacity. The fuel channels have thicker walls than other components (e.g., fuel rods), and the normal amounts of oxidation and hydrogen pickup are not limiting provided: the alloy composition and impurity limits are carefully selected; the heat treatments are also carefully chosen; and the water chemistry is controlled. [
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 19
[
].
Long-Term Creep Deformation. Changes to the geometry of the fuel channel occur due to creep deformation during the long term exposure in the reactor core environment. Overall deformation of the fuel channel occurs from a combination of bulging and bowing. Bulging of the side walls occurs because of the differential pressure across the wall. Lateral bowing of the channel is caused primarily from the neutron flux and thermal gradients. Too much deflection may prevent normal control blade maneuvers and it may increase control blade insertion time above the Technical Specification limits. The total channel deformation must not stop free movement of the control blade.
3.5.2 Design Criteria for Accident Conditions Fuel Channel Stresses and Limit Load. The criteria are based on the ASME B&PV Code,Section III, Appendix F, for faulted conditions (Service Level D). Component support criteria for elastic system analysis are used as defined in paragraphs F-1332.1 and F-1332.2. The unirradiated properties of the fuel channel material are used since the yield and ultimate tensile strength increase during irradiation.
Stresses are alternatively addressed by the plastic analysis collapse load criteria given in paragraph F-1332.2(b). For the plastic analysis collapse load, the permanent deformation is limited to twice the deformation the structure would undergo had the behavior been entirely elastic.
The amount of bulging remains limited to that value which will permit control blade insertion.
Fuel Channel Gusset Load Rating. [
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 20 Table 3-1 Results for ATRIUM 10XM Fuel Assembly Criteria Section Description Criteria Results 3.3 Fuel System Criteria 3.3.1 Stress, strain and loading limits on assembly components The ASME B&PV Code Section III is used to establish acceptable stress levels or load limits for assembly structural components. The design limits for accident conditions are derived from Appendix F of Section III.
[
].
- Water channel The pressure load including AOO is limited to [
] according to ASME B&PV Code Section III. The pressure load is also limited such that [
].
[
].
3.3.2 Fatigue
[
].
[
].
3.3.3 Fretting wear
[
]
Fretting was evaluated by testing. Test results indicate
[
].
3.3.4 Oxidation, hydriding, and crud buildup
[
]
[
].
3.3.5 Rod bow Protect thermal limits NRC accepted model used to compute impact on thermal limits.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 21 Table 3-1 Results for ATRIUM 10XM Fuel Assembly (Continued)
Criteria Section Description Criteria Results 3.3 Fuel System Criteria (Continued) 3.3.6 Axial irradiation growth
- Upper end cap clearance Clearance always exists
[
].
- Seal spring engagement Remains engaged with channel
[
].
3.3.7 Rod internal pressure N/A Not covered in structural report 3.3.8 Assembly liftoff
- Normal operation (including AOOs)
No liftoff from fuel support Net force on assembly is downward.
- Postulated accident No disengagement from fuel support.
Fuel assembly LTP nozzle remains engaged with fuel support. Net force on assembly is downward.
3.3.9 Fuel assembly handling Assembly withstands [
]
Verified by testing to meet requirement.
3.3.10 Miscellaneous components 3.3.10.1 Compression spring forces Support weight of UTP and fuel channel throughout design life The design criteria are met.
3.3.10.2 LTP seal spring Accommodate fuel channel deformation, adequate corrosion, and withstand operating stresses The design criteria are met.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 22 Table 3-1 Results for ATRIUM 10XM Fuel Assembly (Continued)
Criteria Section Description Criteria Results 3.4 Fuel Coolability 3.4.1 Cladding embrittlement N/A Not covered in structural report 3.4.2 Violent expulsion of fuel N/A Not covered in structural report 3.4.3 Fuel ballooning N/A Not covered in structural report 3.4.4 Structural deformations Maintain coolable geometry and ability to insert control blades. SRP 4.2, App. A, and ASME Section III, App. F.
See results below for individual components.
[
].
Fuel rod stresses
[
]
[
]
Spacer grid lateral load
[
]
[
]
Water channel load The combined seismic and pressure load is limited to the
[
] according to ASME B&PV Code Section III, App. F. The pressure load is also limited such that
[
].
[
].
UTP lateral load
[
]
[
]
LTP lateral load
[
]
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 23 Table 3-2 Results for Advanced Fuel Channel Criteria Section Description Criteria Results 3.5 Advanced Fuel Channel - Normal Operation Stress due to pressure differential The pressure load including AOO is limited to [
] according to ASME B&PV Code,Section III.
The pressure load is also limited such that [
].
The deformation during AOO remains within functional limits for normal control blade operation and the [
]. There is no significant plastic deformation during normal operation [
].
Fatigue Cumulative cyclic loading to be less than the design cyclic fatigue life for Zircaloy. [
].
Expected number of cycles
[
] is less than allowable.
Oxidation and hydriding
[
]
The maximum expected oxidation is low in relation to the wall thickness. [
].
Long-term deformation (bulge creep and bow)
Bulge and bow shall not interfere with free movement of the control blade Margin to a stuck control blade remains positive.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 24 Table 3-2 Results for Advanced Fuel Channel (Continued)
Criteria Section Description Criteria Results 3.5 Advanced Fuel Channel - Accident Conditions Fuel channel stresses and load limit The pressure load is limited to
[
] according to ASME B&PV Code,Section III, App. F. The pressure load is also limited such that deformation remains within functional requirements.
The deformation during blowdown does not interfere with control blade insertion [
].
Channel bending from combined horizontal excitations Allowable bending moment based on ASME Code,Section III, Appendix F plastic analysis collapse load
[
].
Fuel channel gusset strength ASME allowable [
] of one gusset is [
].
[
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 25 Table 3-3 Results for Channel Fastener Criteria Section Description Criteria Results 3.5 Channel Fastener Compatibility Spring height must extend to the middle of the control cell to ensure contact with adjacent spring.
Spring axial location must be sufficient to ensure alignment with adjacent spring at all exposures.
All compatibility requirements are met. The spring will extend beyond the cell mid-line.
The axial location of the spring flat will always be in contact with an adjacent spring; even if a fresh ATRIUM 10XM is placed adjacent to an EOL co-resident assembly.
Strength Spring must meet ASME stress criteria and not yield beyond functional limit.
Cap screw must meet ASME criteria for threaded fastener.
All ASME stress criteria are met for the spring and cap screw.
In addition, the spring will not yield under the maximum deflection.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 26 4.0 Mechanical Testing Prototype testing is an essential element of AREVAs methodology for demonstrating compliance with structural design requirements. Results from design verification testing may directly demonstrate compliance with criteria or may be used as input to design analyses.
Testing performed to qualify the mechanical design or evaluate assembly characteristics includes:
Fuel assembly axial load structural strength test Spacer grid lateral impact strength test Tie plate lateral load strength tests and LTP axial compression test Debris filter efficiency test Fuel assembly fretting test Fuel assembly static lateral deflection test Fuel assembly lateral vibration tests Fuel assembly impact tests Summary descriptions of the tests are provided below.
4.1 Fuel Assembly Axial Load Test An axial load test was conducted by applying an axial tensile load between the LTP grid and UTP handle of a fuel assembly cage specimen. The load was slowly applied while monitoring the load and deflection. No significant permanent deformation was detected for loads in excess
[
].
4.2 Spacer Grid Lateral Impact Strength Test Spacer grid impact strength was determined by a [
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 27
[
].
[
].
The maximum force prior to the onset of buckling was determined from the testing. The results were adjusted to reactor operating temperature conditions to establish an allowable lateral load.
4.3 Tie Plate Strength Tests In addition to the axial tensile tests described above, [
].
The UTP [
].
For the advanced debris filter LTP [
].
To determine a limiting lateral load for accident conditions, the LTP [
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 28 4.4 Debris Filter Efficiency Test Debris filtering tests were performed for the advanced debris filter lower tie plate to evaluate its debris filtering efficiency. These tests evaluated the ability of the advanced debris filter to protect the fuel rod array from a wide set of debris forms. In particular, testing was performed
[
]. These debris filtering tests demonstrate that the advanced debris filter is effective at protecting the fuel rod array from all high-risk debris forms.
4.5 Fuel Assembly Fretting Test A fretting test was conducted on a full-size test assembly to evaluate the ATRIUM 10XM fuel rod support design. [
]. After the test, the assembly was inspected for signs of fretting wear. [
].
4.6 Fuel Assembly Static Lateral Deflection Test A lateral deflection test was performed to determine the fuel assembly stiffness, both with and without the fuel channel. The stiffness is obtained by supporting the fuel assembly at the two ends in a vertical position, applying a side displacement at the central spacer location, and measuring the corresponding force.
4.7 Fuel Assembly Lateral Vibration Tests The lateral vibration testing consists of both a free vibration test and a forced vibration test
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 29
[
].
The test setup for the free vibration test [
].
The forced vibration testing [
].
4.8 Fuel Assembly Impact Tests Impact testing was performed [
]. The measured impact loads are used in establishing the spacer grid stiffness.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 30 5.0 References
- 1.
ANF-89-98(P)(A) Revision 1 and Supplement 1, Generic Mechanical Design Criteria for BWR Fuel Designs, Advanced Nuclear Fuels Corporation, May 1995.
- 2.
EMF-93-177(P)(A) Revision 1, Mechanical Design for BWR Fuel Channels, Framatome ANP Inc., August 2005.
- 3.
EMF-85-74(P) Revision 0 Supplement 1(P)(A) and Supplement 2(P)(A), RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model, Siemens Power Corporation, February 1998.
- 4.
XN-NF-75-32(P)(A) Supplements 1 through 4, Computational Procedure for Evaluating Fuel Rod Bowing, Exxon Nuclear Company, October 1983. (Base document not approved.)
- 5.
W. J. ODonnell and B. F. Langer, Fatigue Design Basis for Zircaloy Components, Nuclear Science and Engineering, Volume 20, January 1964.
- 6.
XN-NF-81-51(P)(A), LOCA - Seismic Structural Response of an Exxon Nuclear Company BWR Jet Pump Fuel Assembly, Exxon Nuclear Company, May 1986.
- 7.
XN-NF-84-97(P)(A), LOCA - Seismic Structural Response of an ENC 9x9 BWR Jet Pump Fuel Assembly, Exxon Nuclear Company, August 1986.
- 8.
Huan, P. Y., Mahmood, S. T., and Adamson, R. B. Effects of Thermomechanical Processing on In-Reactor Corrosion and Post-Irradiation Properties of Zircaloy-2, Zirconium in the Nuclear Industry: Eleventh International Symposium, ASTM STP 1295, E. R. Bradley and G. P. Sabol, Eds., American Society for Testing and Materials, 1996, pp. 726-757.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 31 Appendix A Illustrations The following table lists the fuel assembly and fuel channel component illustrations in this section:
Description Page ATRIUM 10XM Fuel Assembly 32 UTP with Locking Hardware 33 Lower Tie Plate 34 ATRIUM 10XM ULTRAFLOW Spacer Grid 35 Fuel and Part-Length Fuel Rods 36 Advanced Fuel Channel 37 Fuel Channel Fastener Assembly 38 These illustrations are for descriptive purpose only. Please refer to the current reload design package for product dimensions and specifications.
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Figure A-1 ATRIUM 10XM Fuel Assembly (not to scale)
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Figure A-2 UTP with Locking Hardware AREVA Inc.
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]
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Figure A-3 Lower Tie Plate AREVA Inc.
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Figure A-4 ATRIUM 10XM ULTRAFLOW Spacer Grid AREVA Inc.
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Figure A-5 Full and Part-Length Fuel Rods AREVA Inc.
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(not to scale)
Figure A-6 Advanced Fuel Channel AREVA Inc.
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Figure A-7 Fuel Channel Fastener Assembly AREVA Inc.
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ATTACHMENT 25 ANP-3386NP, Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies (Non-Proprietary)
ANP-3386NP Revision 1 Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU)
ATRIUM 10XM Fuel Assemblies Licensing Report August 2015 AREVA Inc.
(c) 2015 AREVA Inc.
ANP-3386NP Revision 1 Copyright © 2015 AREVA Inc.
All Rights Reserved
AREVA Inc.
Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page i Nature of Changes Item Revision Number Section(s) or Page(s)
Description and Justification
- 1.
0 All This is a new document.
- 2.
1 All Updated proprietary bracketing for consistency.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page ii Contents 1.0 Introduction..................................................................................................................... 1 2.0 Design Description.......................................................................................................... 3 2.1 Fuel Assembly..................................................................................................... 3 2.1.1 Spacer Grid............................................................................................ 3 2.1.2 Water Channel....................................................................................... 4 2.1.3 Lower Tie Plate...................................................................................... 4 2.1.4 Upper Tie Plate and Connecting Hardware............................................ 5 2.1.5 Fuel Rods.............................................................................................. 5 2.2 Fuel Channel and Components............................................................................ 6 3.0 Fuel Design Evaluation.................................................................................................. 10 3.1 Objectives.......................................................................................................... 10 3.2 Fuel Rod Evaluation........................................................................................... 10 3.3 Fuel System Evaluation..................................................................................... 11 3.3.1 Stress, Strain, or Loading Limits on Assembly Components......................................................................................... 11 3.3.2 Fatigue................................................................................................. 12 3.3.3 Fretting Wear....................................................................................... 12 3.3.4 Oxidation, Hydriding, and Crud Buildup................................................ 12 3.3.5 Rod Bow.............................................................................................. 13 3.3.6 Axial Irradiation Growth........................................................................ 13 3.3.7 Rod Internal Pressure.......................................................................... 14 3.3.8 Assembly Lift-off.................................................................................. 14 3.3.9 Fuel Assembly Handling....................................................................... 15 3.3.10 Miscellaneous Component Criteria....................................................... 15 3.3.10.1 Compression Spring Forces................................................. 15 3.3.10.2 LTP Seal Spring................................................................... 16 3.4 Fuel Coolability.................................................................................................. 16 3.4.1 Cladding Embrittlement........................................................................ 16 3.4.2 Violent Expulsion of Fuel...................................................................... 16 3.4.3 Fuel Ballooning.................................................................................... 16 3.4.4 Structural Deformations....................................................................... 16 3.5 Fuel Channel and Fastener................................................................................ 18 3.5.1 Design Criteria for Normal Operation................................................... 18 3.5.2 Design Criteria for Accident Conditions................................................ 19 4.0 Mechanical Testing........................................................................................................ 26 4.1 Fuel Assembly Axial Load Test.......................................................................... 26 4.2 Spacer Grid Lateral Impact Strength Test.......................................................... 26 4.3 Tie Plate Strength Tests..................................................................................... 27 4.4 Debris Filter Efficiency Test............................................................................... 28 4.5 Fuel Assembly Fretting Test.............................................................................. 28 4.6 Fuel Assembly Static Lateral Deflection Test..................................................... 28 4.7 Fuel Assembly Lateral Vibration Tests............................................................... 28 4.8 Fuel Assembly Impact Tests.............................................................................. 29 AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page iii 5.0 References.................................................................................................................... 30 Appendix A Illustrations...................................................................................................... 31 Tables Table 2-1 Fuel Assembly and Component Description............................................................... 7 Table 2-2 Fuel Channel and Fastener Description..................................................................... 9 Table 3-1 Results for ATRIUM 10XM Fuel Assembly............................................................... 20 Table 3-2 Results for Advanced Fuel Channel......................................................................... 23 Table 3-3 Results for Channel Fastener................................................................................... 25 Figures Figure A-1 ATRIUM 10XM Fuel Assembly (not to scale).......................................................... 32 Figure A-2 UTP with Locking Hardware................................................................................... 33 Figure A-3 Lower Tie Plate....................................................................................................... 34 Figure A-4 ATRIUM 10XM ULTRAFLOW Spacer Grid............................................................. 35 Figure A-5 Full and Part-Length Fuel Rods.............................................................................. 36 Figure A-6 Advanced Fuel Channel......................................................................................... 37 Figure A-7 Fuel Channel Fastener Assembly........................................................................... 38 This document contains a total of 44 pages.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page iv Nomenclature Acronym Definition AFC Advanced Fuel Channel AOO Anticipated Operational Occurrences ASME American Society of Mechanical Engineers B&PV Boiler and Pressure Vessel BOL Beginning of Life BWR Boiling Water Reactor CHF Critical Heat Flux EOL End of Life HALC Harmonized Advanced Load Chain LOCA Loss-of-Coolant Accident LTP Lower Tie Plate MWd/kgU Megawatt-days per kilogram of Uranium NRC U. S. Nuclear Regulatory Commission PLFR Part-Length Fuel Rods psi Pounds per square inch Sm Design stress intensity SRA Stress Relief Annealed SRP Standard Review Plan Su Ultimate stress Sy Yield stress UTP Upper Tie Plate AREVA Inc.
AREVA Inc.
Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 1 1.0 Introduction The purpose of this report is to show that the AREVA Inc. (AREVA) fuel mechanical design criteria are satisfied at Browns Ferry EPU conditions (120 percent of original licensed thermal power (OLTP)). This report provides a design description, mechanical design criteria, fuel structural analysis results, and test results for the ATRIUM'* 10XM fuel assembly and 100/75 Advanced Fuel Channel (AFC) designs supplied by AREVA Inc. (AREVA) for use at Browns Ferry Units 1, 2 and 3.
The scope of this report is limited to an evaluation of the structural design of the fuel assembly and fuel channel. The fuel assembly structural design evaluation is not cycle-specific so this report is intended to be referenced for each cycle where the fuel design is in use. Minor changes to the fuel design and cycle-specific input parameters will be dispositioned for future reloads. AREVA will confirm the continued applicability of this report prior to delivery of each subsequent reload of ATRIUM 10XM fuel at Browns Ferry Units 1, 2 and 3.
Many of the structural analyses of the fuel assembly are done on a generic basis. However, the increase in core power for EPU is also associated with an increase in core pressure drop which does have an effect on some mechanical analyses. This increase in pressure specifically affects the fuel assembly liftoff analyses and the calculated stress and deformation of the fuel channel and water channel. These analyses were revisited and shown to maintain design margin.
The fuel assembly design was evaluated according to the AREVA boiling water reactor (BWR) generic mechanical design criteria (Reference 1). The fuel channel design was evaluated to the criteria given in the fuel channel topical report (Reference 2). The generic design criteria have been approved by the U.S. Nuclear Regulatory Commission (NRC) and the criteria are applicable to the subject fuel assembly and channel design.
Mechanical analyses have been performed using NRC-approved design analysis methodology (References 1, 2, 3, and 4). The methodology permits maximum licensed assembly and fuel channel exposures of [
] (Reference 3). Documentation of compliance with the ATRIUM is a trademark of AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 2 generic design criteria using approved methods demonstrates licensing approval of the fuel design.
The fuel assembly and channel meets all mechanical compatibility requirements for use in Browns Ferry Units 1, 2 and 3. This includes compatibility with both co-resident fuel and the reactor core internals.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 3 2.0 Design Description This report documents the structural evaluation of the ATRIUM 10XM fuel assembly and fuel channel described below. Reload-specific design information is available in the design package provided by AREVA for each reload delivery.
2.1 Fuel Assembly The ATRIUM 10XM fuel assembly consists of a lower tie plate (LTP) and upper tie plate (UTP),
91 fuel rods, [
] spacer grids, a central water channel with [
],
and miscellaneous assembly hardware. Of the 91 fuel rods, [
] are PLFRs. The structural members of the fuel assembly include the tie plates, spacer grids, water channel, and connecting hardware. [
].
The fuel assembly is accompanied by a fuel channel, as described later in this section.
Table 2-1 lists the main fuel assembly attributes, and an illustration of the fuel bundle assembly is provided in Appendix A.
2.1.1 Spacer Grid The spacer grid is a [
] version of the ULTRAFLOW' design. [
].
ULTRAFLOW is a trademark of AREVA Inc.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 4 Table 2-1 lists the main spacer grid attributes, and an illustration of the spacer grid is provided in Appendix A.
2.1.2 Water Channel
[
].
Table 2-1 lists the main water channel attributes and Appendix A provides an illustration of a section of the water channel.
2.1.3 Lower Tie Plate The diffuser box of the LTP [
].
Appendix A provides a generic illustration of the LTP.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 5 2.1.4 Upper Tie Plate and Connecting Hardware
[
].
Appendix A provides an illustration of the UTP and locking components.
2.1.5 Fuel Rods
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 6
[
].
Table 2-1 lists the main fuel rod attributes, and Appendix A provides an illustration of the full length and part length fuel rods.
2.2 Fuel Channel and Components
[
].
Table 2-2 lists the fuel channel component attributes. The fuel channel and fuel channel fastener are depicted in Appendix A.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 7 Table 2-1 Fuel Assembly and Component Description
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 8 Table 2-1 Fuel Assembly and Component Description (Continued)
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 9 Table 2-2 Fuel Channel and Fastener Description
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 10 3.0 Fuel Design Evaluation A summary of the mechanical methodology and results from the structural design evaluations is provided in this section. Results from the mechanical design evaluation demonstrate that the design satisfies the mechanical criteria to the analyzed exposure limit.
3.1 Objectives The objectives of designing fuel assemblies (systems) to specific criteria are to provide assurance that:
The fuel assembly (system) shall not fail as a result of normal operation and anticipated operational occurrences (AOOs). The fuel assembly (system) dimensions shall be designed to remain within operational tolerances, and the functional capabilities of the fuels shall be established to either meet or exceed those assumed in the safety analysis.
Fuel assembly (system) damage shall never prevent control rod insertion when it is required.
The number of fuel rod failures shall be conservatively estimated for postulated accidents.
Fuel coolability shall always be maintained.
The mechanical design of fuel assemblies shall be compatible with co-resident fuel and the reactor core internals.
Fuel assemblies shall be designed to withstand the loads from handling and shipping.
The first four objectives are those cited in the Standard Review Plan (SRP). The latter two objectives are to assure the structural integrity of the fuel and the compatibility with the existing reload fuel. To satisfy these objectives, the criteria are applied to the fuel rod and the fuel assembly (system) designs. Specific component criteria are also necessary to assure compliance. The criteria established to meet these objectives include those given in Chapter 4.2 of the SRP.
3.2 Fuel Rod Evaluation The mechanical design report documents the fuel structural analyses only. The fuel rod evaluation is performed each cycle and is documented in the Browns Ferry cycle specific fuel rod thermal-mechanical report.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 11 3.3 Fuel System Evaluation The detailed fuel system design evaluation is performed to ensure the structural integrity of the design under normal operation, AOO, faulted conditions, handling operations, and shipping.
The analysis methods are based on fundamental mechanical engineering techniquesoften employing finite element analysis, prototype testing, and correlations based on in-reactor performance data. Summaries of the major assessment topics are described in the sections that follow.
3.3.1 Stress, Strain, or Loading Limits on Assembly Components The structural integrity of the fuel assemblies is assured by setting design limits on stresses and deformations due to various handling, operational, and accident or faulted loads. AREVA uses Section Ill of the ASME B&PV Code as a guide to establish acceptable stress, deformation, and load limits for standard assembly components. These limits are applied to the design and evaluation of the UTP, LTP, spacer grids, springs, and load chain components, as applicable.
The fuel assembly structural component criteria under faulted conditions are based on Appendix F of the ASME B&PV Code Section III with some criteria derived from component tests.
All significant loads experienced during normal operation, AOOs, and under faulted conditions are evaluated to confirm the structural integrity of the fuel assembly components. Outside of faulted conditions, most structural components are under the most limiting loading conditions during fuel handling. See Section 3.3.9 for a discussion of fuel handling loads and Section 3.4.4 for the structural evaluation of faulted conditions. Although normal operation and AOO loads are often not limiting for structural components, a stress evaluation may be performed to confirm the design margin and to establish a baseline for adding accident loads. The stress calculations use conventional, open-literature equations. A general-purpose, finite element stress analysis code, such as ANSYS, may be used to calculate component stresses.
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 12
[
].
See Table 3-1 for results from the component strength evaluations.
3.3.2 Fatigue Fatigue of structural components is generally [
].
3.3.3 Fretting Wear Fuel rod failures due to grid-to-rod fretting shall not occur. [
].
Fretting wear is evaluated by testing, as described in Section 4.5. The testing is conducted by
[
]. The inspection measurements for wear are documented. [
].
[
] and has operated successfully without incidence of grid-to-rod fretting in more than 20,000 fuel assemblies.
3.3.4 Oxidation, Hydriding, and Crud Buildup Because of the low amount of corrosion on fuel assembly structural components, [
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 13
[
].
3.3.5 Rod Bow Differential expansion between the fuel rods and cage structure, and lateral thermal and flux gradients can lead to lateral creep bow of the rods in the spans between spacer grids. This lateral creep bow alters the pitch between the rods and may affect the peaking and local heat transfer. The AREVA design criterion for fuel rod bowing is that [
].
Rod bow is calculated using the approved model described in Reference 4. [
]. The predicted rod-to-rod gap closure due to bow is assessed for impact on thermal margins.
3.3.6 Axial Irradiation Growth Fuel assembly components, including the fuel channel, shall maintain clearances and engagements, as appropriate, throughout the design life. Three specific growth calculations are considered for the ATRIUM 10XM design:
Minimum fuel rod clearance between the LTP and UTP Minimum engagement of the fuel channel with the LTP seal spring External interfaces (e.g., channel fastener springs)
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 14 Rod growth, assembly growth, and fuel channel growth are calculated using correlations derived from post-irradiation data. The evaluation of initial engagements and clearances accounts for the combination of fabrication tolerances on individual component dimensions.
The SRA fuel rod growth correlation was established from [
]. Assembly growth is dictated by the water channel growth. The growth of the water channel and the fuel channel is based on [
]. These data and the resulting growth correlations are described in Reference 3. The upper and lower [
], as appropriate, are used to obtain EOL growth values.
The minimum EOL rod growth clearance and EOL fuel channel engagement with the seal spring are listed in Table 3-1. The channel fastener spring axial compatibility is reported in Table 3-3.
3.3.7 Rod Internal Pressure This is addressed in the Browns Ferry fuel rod thermal-mechanical report.
3.3.8 Assembly Lift-off Fuel assembly lift-off is evaluated under both normal operating conditions (including AOOs) and under faulted conditions. The fuel shall not levitate under normal operating or AOO conditions.
Under postulated accident conditions, the fuel shall not become disengaged from the fuel support. These criteria assure control blade insertion is not impaired.
For normal operating conditions, the net axial force acting on the fuel assembly is calculated by adding the loads from gravity, hydraulic resistance from coolant flow, difference in fluid flow entrance and exit momentum, and buoyancy. The calculated net force is confirmed to be in the downward direction, indicating no assembly lift-off. Maximum hot channel conditions are used in the calculation because the greater two-phase flow losses produce a higher uplift force.
Mixed core conditions for assembly lift-off are considered on a cycle-specific basis, as determined by the plant and other fuel types. Analyses to date indicate a large margin to assembly lift-off under normal operating conditions. Therefore, fuel lift-off in BWRs under normal operating conditions is considered to be a small concern.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 15 For faulted conditions, [
]. The uplift is limited to be less than the axial engagement such that the fuel assembly neither becomes laterally displaced nor blocks insertion of the control blade.
3.3.9 Fuel Assembly Handling The fuel assembly shall withstand, without permanent deformation, all normal axial loads from shipping and fuel handling operations. Analysis or testing shall show that the fuel is capable of
[
].
The fuel assembly structural components are assessed for axial fuel handling loads by testing.
To demonstrate compliance with the criteria, the test is performed by loading a test assembly to an axial tensile force greater than [
]. An acceptable test shows no yielding after loading. The testing is described further in Section 4.1.
There are also handling requirements for the fuel rod plenum spring which are addressed in the Browns Ferry fuel rod thermal-mechanical report.
3.3.10 Miscellaneous Component Criteria 3.3.10.1 Compression Spring Forces The ATRIUM 10XM has a single large compression spring mounted on the central water channel. The compression spring serves the same function as previous designs by providing support for the UTP and fuel channel. The spring force is calculated based on the deflection and specified spring force requirements. Irradiation-induced relaxation is taken into account for EOL conditions. The minimum compression spring force at EOL is shown to be greater than the combined weight of the UTP and fuel channel (including channel fastener hardware). Since the compression spring does not interact with the fuel rods, no consideration is required for fuel rod buckling loads.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 16 3.3.10.2 LTP Seal Spring The LTP seal spring shall limit the bypass coolant leakage rate between the LTP and fuel channel. The seal spring shall accommodate expected channel deformation while remaining in contact with the fuel channel. Also, the seal spring shall have adequate corrosion resistance and be able to withstand the operating stresses without yielding.
Flow testing is used to confirm acceptable bypass flow characteristics. The seal spring is designed with adequate deflection to accommodate the maximum expected channel bulge while maintaining acceptable bypass flow. [
] is selected as the material because of its high strength at elevated temperature and its excellent corrosion resistance. Seal spring stresses are analyzed using a finite element method.
3.4 Fuel Coolability For accidents in which severe fuel damage might occur, core coolability and the capability to insert control blades are essential. Chapter 4.2 of the SRP provides several specific areas important to fuel coolability, as discussed below.
3.4.1 Cladding Embrittlement This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.2 Violent Expulsion of Fuel This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.3 Fuel Ballooning This evaluation is not part of the structural analysis and is covered separate from this report.
3.4.4 Structural Deformations The methodology for analyzing the fuel under the influence of seismic/LOCA analysis loads is described in References 2, 6 and 7. Evaluations performed for the fuel under combined seismic/LOCA loadings include mechanical fracturing of the fuel rod cladding, assembly structural integrity, and fuel assembly liftoff. Restricting fuel uplift and limiting fuel channel deformation under accident conditions permit insertion of the control blades.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 17 The testing and analyses have shown the dynamic response of the ATRIUM 10XM design to be very similar to the ATRIUM-10. The ATRIUM-10 fuel assembly has been evaluated for integrity during external loading by testing and analysis. Testing is done to obtain the dynamic characteristics of the fuel assembly and spacer grids. The stiffnesses, natural frequencies and damping values derived from the tests are used as inputs for dynamic mechanical models of the fuel assembly and fuel channel. Tests are done with and without a fuel channel. In addition, the dynamic models are compared to the test results to ensure an accurate characterization of the fuel. See Section 4.0 for descriptions of testing.
[
].
Similar to the ATRIUM-10, the ATRIUM 10XM assembly will be delivered to Browns Ferry with the AFC design. Given that the [
] is the limiting component, the fuel assembly component loads and stresses calculated for the ATRIUM-10 will remain applicable to the ATRIUM 10XM. Table 3-3 lists the margins for fuel assembly components at the maximum acceleration allowed for the channel design. Component load and stress limits are derived using the ASME B&PV Code,Section III, Division 1, Appendix F, and SRP Section 4.2, Appendix A. Specified tensile properties or testing are used to establish the limits.
In general, the dynamic responses of the ATRIUM 10XM and the ATRIUM-10 are very similar to other BWR fuel designs that have the same basic channel configuration and weight. This includes the previously analyzed GNF fuel at Browns Ferry. In addition, the original or revised seismic/LOCA reactor pressure vessel analyses performed to determine maximum core accelerations, deflections, and loads will apply to the ATRIUM 10XM because of the dynamic similarity with past designs. The dynamic response of the channeled ATRIUM 10XM fuel assembly is primarily dependent on the fuel channel stiffness and the fuel assembly mass.
Because the fuel assembly weight and channel stiffness do not vary significantly from prior AREVA fuel designs (or other co-resident fuel types), the maximum loads and deflections for the ATRIUM 10XM fuel assembly will be essentially unchanged from before.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 18 Assembly liftoff under accident conditions is described in Section 3.3.8.
3.5 Fuel Channel and Fastener The fuel channel and fastener design criteria are summarized below, and evaluation results are summarized in Table 3-2 and Table 3-3. The analysis methods are described in detail in Reference 2.
3.5.1 Design Criteria for Normal Operation Steady-State Stress Limits. The stress limits during normal operation are obtained from the ASME B&PV Code,Section III, Division 1, Subsection NG for Service Level A. The calculated stress intensities are due to the differential pressure across the channel wall. The pressure loading includes the normal operating pressure plus the increase during AOO. The unirradiated properties of the fuel channel material are used since the yield and ultimate tensile strength increase during irradiation (Reference 8).
As an alternative to the elastic analysis stress intensity limits, a plastic analysis may be performed as permitted by paragraph NB-3228.3 of the ASME B&PV Code.
In the case of AOOs, the amount of bulging is limited to that value which will permit control blade movement. During normal operation, any significant permanent deformation due to yielding is precluded by restricting the maximum stresses at the inner and outer faces of the channel to be less than the yield strength.
Fuel Channel Fatigue. Cyclic changes in power and flow during operation impose a duty loading on the fuel channel. [
].
Corrosion and Hydrogen Concentration. Corrosion reduces the material thickness and results in less load-carrying capacity. The fuel channels have thicker walls than other components (e.g., fuel rods), and the normal amounts of oxidation and hydrogen pickup are not limiting provided: the alloy composition and impurity limits are carefully selected; the heat treatments are also carefully chosen; and the water chemistry is controlled. [
]
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[
].
Long-Term Creep Deformation. Changes to the geometry of the fuel channel occur due to creep deformation during the long term exposure in the reactor core environment. Overall deformation of the fuel channel occurs from a combination of bulging and bowing. Bulging of the side walls occurs because of the differential pressure across the wall. Lateral bowing of the channel is caused primarily from the neutron flux and thermal gradients. Too much deflection may prevent normal control blade maneuvers and it may increase control blade insertion time above the Technical Specification limits. The total channel deformation must not stop free movement of the control blade.
3.5.2 Design Criteria for Accident Conditions Fuel Channel Stresses and Limit Load. The criteria are based on the ASME B&PV Code,Section III, Appendix F, for faulted conditions (Service Level D). Component support criteria for elastic system analysis are used as defined in paragraphs F-1332.1 and F-1332.2. The unirradiated properties of the fuel channel material are used since the yield and ultimate tensile strength increase during irradiation.
Stresses are alternatively addressed by the plastic analysis collapse load criteria given in paragraph F-1332.2(b). For the plastic analysis collapse load, the permanent deformation is limited to twice the deformation the structure would undergo had the behavior been entirely elastic.
The amount of bulging remains limited to that value which will permit control blade insertion.
Fuel Channel Gusset Load Rating. [
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 20 Table 3-1 Results for ATRIUM 10XM Fuel Assembly Criteria Section Description Criteria Results 3.3 Fuel System Criteria 3.3.1 Stress, strain and loading limits on assembly components The ASME B&PV Code Section III is used to establish acceptable stress levels or load limits for assembly structural components. The design limits for accident conditions are derived from Appendix F of Section III.
[
].
- Water channel The pressure load including AOO is limited to [
] according to ASME B&PV Code Section III. The pressure load is also limited such that [
].
[
].
3.3.2 Fatigue
[
].
[
].
3.3.3 Fretting wear
[
]
Fretting was evaluated by testing. Test results indicate
[
].
3.3.4 Oxidation, hydriding, and crud buildup
[
]
[
].
3.3.5 Rod bow Protect thermal limits NRC accepted model used to compute impact on thermal limits.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 21 Table 3-1 Results for ATRIUM 10XM Fuel Assembly (Continued)
Criteria Section Description Criteria Results 3.3 Fuel System Criteria (Continued) 3.3.6 Axial irradiation growth
- Upper end cap clearance Clearance always exists
[
].
- Seal spring engagement Remains engaged with channel
[
].
3.3.7 Rod internal pressure N/A Not covered in structural report 3.3.8 Assembly liftoff
- Normal operation (including AOOs)
No liftoff from fuel support Net force on assembly is downward.
- Postulated accident No disengagement from fuel support.
Fuel assembly LTP nozzle remains engaged with fuel support. Net force on assembly is downward.
3.3.9 Fuel assembly handling Assembly withstands [
]
Verified by testing to meet requirement.
3.3.10 Miscellaneous components 3.3.10.1 Compression spring forces Support weight of UTP and fuel channel throughout design life The design criteria are met.
3.3.10.2 LTP seal spring Accommodate fuel channel deformation, adequate corrosion, and withstand operating stresses The design criteria are met.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 22 Table 3-1 Results for ATRIUM 10XM Fuel Assembly (Continued)
Criteria Section Description Criteria Results 3.4 Fuel Coolability 3.4.1 Cladding embrittlement N/A Not covered in structural report 3.4.2 Violent expulsion of fuel N/A Not covered in structural report 3.4.3 Fuel ballooning N/A Not covered in structural report 3.4.4 Structural deformations Maintain coolable geometry and ability to insert control blades. SRP 4.2, App. A, and ASME Section III, App. F.
See results below for individual components.
[
].
Fuel rod stresses
[
]
[
]
Spacer grid lateral load
[
]
[
]
Water channel load The combined seismic and pressure load is limited to the
[
] according to ASME B&PV Code Section III, App. F. The pressure load is also limited such that
[
].
[
].
UTP lateral load
[
]
[
]
LTP lateral load
[
]
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 23 Table 3-2 Results for Advanced Fuel Channel Criteria Section Description Criteria Results 3.5 Advanced Fuel Channel - Normal Operation Stress due to pressure differential The pressure load including AOO is limited to [
] according to ASME B&PV Code,Section III.
The pressure load is also limited such that [
].
The deformation during AOO remains within functional limits for normal control blade operation and the [
]. There is no significant plastic deformation during normal operation [
].
Fatigue Cumulative cyclic loading to be less than the design cyclic fatigue life for Zircaloy. [
].
Expected number of cycles
[
] is less than allowable.
Oxidation and hydriding
[
]
The maximum expected oxidation is low in relation to the wall thickness. [
].
Long-term deformation (bulge creep and bow)
Bulge and bow shall not interfere with free movement of the control blade Margin to a stuck control blade remains positive.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 24 Table 3-2 Results for Advanced Fuel Channel (Continued)
Criteria Section Description Criteria Results 3.5 Advanced Fuel Channel - Accident Conditions Fuel channel stresses and load limit The pressure load is limited to
[
] according to ASME B&PV Code,Section III, App. F. The pressure load is also limited such that deformation remains within functional requirements.
The deformation during blowdown does not interfere with control blade insertion [
].
Channel bending from combined horizontal excitations Allowable bending moment based on ASME Code,Section III, Appendix F plastic analysis collapse load
[
].
Fuel channel gusset strength ASME allowable [
] of one gusset is [
].
[
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 25 Table 3-3 Results for Channel Fastener Criteria Section Description Criteria Results 3.5 Channel Fastener Compatibility Spring height must extend to the middle of the control cell to ensure contact with adjacent spring.
Spring axial location must be sufficient to ensure alignment with adjacent spring at all exposures.
All compatibility requirements are met. The spring will extend beyond the cell mid-line.
The axial location of the spring flat will always be in contact with an adjacent spring; even if a fresh ATRIUM 10XM is placed adjacent to an EOL co-resident assembly.
Strength Spring must meet ASME stress criteria and not yield beyond functional limit.
Cap screw must meet ASME criteria for threaded fastener.
All ASME stress criteria are met for the spring and cap screw.
In addition, the spring will not yield under the maximum deflection.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 26 4.0 Mechanical Testing Prototype testing is an essential element of AREVAs methodology for demonstrating compliance with structural design requirements. Results from design verification testing may directly demonstrate compliance with criteria or may be used as input to design analyses.
Testing performed to qualify the mechanical design or evaluate assembly characteristics includes:
Fuel assembly axial load structural strength test Spacer grid lateral impact strength test Tie plate lateral load strength tests and LTP axial compression test Debris filter efficiency test Fuel assembly fretting test Fuel assembly static lateral deflection test Fuel assembly lateral vibration tests Fuel assembly impact tests Summary descriptions of the tests are provided below.
4.1 Fuel Assembly Axial Load Test An axial load test was conducted by applying an axial tensile load between the LTP grid and UTP handle of a fuel assembly cage specimen. The load was slowly applied while monitoring the load and deflection. No significant permanent deformation was detected for loads in excess
[
].
4.2 Spacer Grid Lateral Impact Strength Test Spacer grid impact strength was determined by a [
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 27
[
].
[
].
The maximum force prior to the onset of buckling was determined from the testing. The results were adjusted to reactor operating temperature conditions to establish an allowable lateral load.
4.3 Tie Plate Strength Tests In addition to the axial tensile tests described above, [
].
The UTP [
].
For the advanced debris filter LTP [
].
To determine a limiting lateral load for accident conditions, the LTP [
].
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 28 4.4 Debris Filter Efficiency Test Debris filtering tests were performed for the advanced debris filter lower tie plate to evaluate its debris filtering efficiency. These tests evaluated the ability of the advanced debris filter to protect the fuel rod array from a wide set of debris forms. In particular, testing was performed
[
]. These debris filtering tests demonstrate that the advanced debris filter is effective at protecting the fuel rod array from all high-risk debris forms.
4.5 Fuel Assembly Fretting Test A fretting test was conducted on a full-size test assembly to evaluate the ATRIUM 10XM fuel rod support design. [
]. After the test, the assembly was inspected for signs of fretting wear. [
].
4.6 Fuel Assembly Static Lateral Deflection Test A lateral deflection test was performed to determine the fuel assembly stiffness, both with and without the fuel channel. The stiffness is obtained by supporting the fuel assembly at the two ends in a vertical position, applying a side displacement at the central spacer location, and measuring the corresponding force.
4.7 Fuel Assembly Lateral Vibration Tests The lateral vibration testing consists of both a free vibration test and a forced vibration test
[
]
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 29
[
].
The test setup for the free vibration test [
].
The forced vibration testing [
].
4.8 Fuel Assembly Impact Tests Impact testing was performed [
]. The measured impact loads are used in establishing the spacer grid stiffness.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 30 5.0 References
- 1.
ANF-89-98(P)(A) Revision 1 and Supplement 1, Generic Mechanical Design Criteria for BWR Fuel Designs, Advanced Nuclear Fuels Corporation, May 1995.
- 2.
EMF-93-177(P)(A) Revision 1, Mechanical Design for BWR Fuel Channels, Framatome ANP Inc., August 2005.
- 3.
EMF-85-74(P) Revision 0 Supplement 1(P)(A) and Supplement 2(P)(A), RODEX2A (BWR) Fuel Rod Thermal-Mechanical Evaluation Model, Siemens Power Corporation, February 1998.
- 4.
XN-NF-75-32(P)(A) Supplements 1 through 4, Computational Procedure for Evaluating Fuel Rod Bowing, Exxon Nuclear Company, October 1983. (Base document not approved.)
- 5.
W. J. ODonnell and B. F. Langer, Fatigue Design Basis for Zircaloy Components, Nuclear Science and Engineering, Volume 20, January 1964.
- 6.
XN-NF-81-51(P)(A), LOCA - Seismic Structural Response of an Exxon Nuclear Company BWR Jet Pump Fuel Assembly, Exxon Nuclear Company, May 1986.
- 7.
XN-NF-84-97(P)(A), LOCA - Seismic Structural Response of an ENC 9x9 BWR Jet Pump Fuel Assembly, Exxon Nuclear Company, August 1986.
- 8.
Huan, P. Y., Mahmood, S. T., and Adamson, R. B. Effects of Thermomechanical Processing on In-Reactor Corrosion and Post-Irradiation Properties of Zircaloy-2, Zirconium in the Nuclear Industry: Eleventh International Symposium, ASTM STP 1295, E. R. Bradley and G. P. Sabol, Eds., American Society for Testing and Materials, 1996, pp. 726-757.
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Mechanical Design Report for Browns Ferry Units 1, 2 and 3 Extended Power Uprate (EPU) ATRIUM 10XM Fuel Assemblies ANP-3386NP Revision 1 Licensing Report Page 31 Appendix A Illustrations The following table lists the fuel assembly and fuel channel component illustrations in this section:
Description Page ATRIUM 10XM Fuel Assembly 32 UTP with Locking Hardware 33 Lower Tie Plate 34 ATRIUM 10XM ULTRAFLOW Spacer Grid 35 Fuel and Part-Length Fuel Rods 36 Advanced Fuel Channel 37 Fuel Channel Fastener Assembly 38 These illustrations are for descriptive purpose only. Please refer to the current reload design package for product dimensions and specifications.
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Figure A-1 ATRIUM 10XM Fuel Assembly (not to scale)
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Figure A-2 UTP with Locking Hardware AREVA Inc.
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Figure A-3 Lower Tie Plate AREVA Inc.
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Figure A-4 ATRIUM 10XM ULTRAFLOW Spacer Grid AREVA Inc.
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Figure A-5 Full and Part-Length Fuel Rods AREVA Inc.
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(not to scale)
Figure A-6 Advanced Fuel Channel AREVA Inc.
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Figure A-7 Fuel Channel Fastener Assembly AREVA Inc.
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