ML13200A191
| ML13200A191 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/31/2012 |
| From: | AREVA NP |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13200A185 | List: |
| References | |
| L-MT-13-055 ANP-3119NP, Rev 0 | |
| Download: ML13200A191 (46) | |
Text
Enclosure 9 AREVA Report ANP-3119(NP)
Mechanical Design Report for Monticello ATRIUM 1OXM Fuel Assemblies Revision 0 45 pages follow
uontroiieci Luocument ANP-3119NP Revision 0 Mechanical Design Report for Monticello ATRIUM TM 1OXM Fuel Assemblies October 2012 A
AREVA NP Inc. AREVA
uontrollea Document AREVA NP Inc.
ANP-3119NP Revision 0 Mechanical Design Report for Monticello ATRIUM TM 1OXM Fuel Assemblies
uontrolled Uocument AREVA NP Inc.
ANP-3119NP Revision 0 Copyright © 2012 AREVA NP Inc.
All Rights Reserved
Uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Paoei Nature of Changes Revision Section(s)
Item Number or Page(s) Description and Justification
- 1. 0 All This is the initial release.
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Uontroiied AREVA NP uocument ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page ii Contents 1 .0 Intro d u ctio n ....................................................................................................................... 1 2.0 Design Description ..................................................................................................... 2 2.1 Overview ....................................................................................................... 2 2.2 Fuel Assem bly .................................................................................................. 2 2.2.1 Spacer Grid ........................................................................................ 2 2.2.2 Water Channel ................................................................................... 3 2.2.3 Lower Tie Plate .................................................................................... 3 2.2.4 Upper Tie Plate and Connecting Hardware ........................................ 4 2.2.5 Fuel Rods ........................................................................................... 5 2.3 Fuel Channel and Com ponents ......................................................................... 5 3.0 Fuel Design Evaluation ................................................................................................. 9 3.1 Objectives ....................................................................................................... 9 3.2 Fuel Rod Evaluation ........................................................................................... 9 3.3 Fuel System Evaluation .................................................................................. 10 3.3.1 Stress, Strain, or Loading Limits on Assembly Com ponents ...................................................................................... 10 3.3.2 Fatigue ............................................................................................... 11 3.3.3 Fretting Wear ..................................................................................... 11 3.3.4 Oxidation, Hydriding, and Crud Buildup ............................................ 11 3.3.5 Rod Bow ........................................................................................... 12 3.3.6 Axial Irradiation Growth .................................................................... 12 3.3.7 Rod Internal Pressure ...................................................................... 13 3.3.8 Assem bly Lift-off ................................................................................ 13 3.3.9 Fuel Assem bly Handling ..................................................................... 14 3.3.10 Miscellaneous Com ponent Criteria .................................................. 14 3.3.10.1 Com pression Spring Forces .............................................. 14 3.3.10.2 LTP Seal Spring ................................................................ 14 3.4 Fuel Coolability ............................................................................................... 15 3.4.1 Cladding Em brittlem ent ..................................................................... 15 3.4.2 Violent Expulsion of Fuel .................................................................. 15 3.4.3 Fuel Ballooning .................................................................................. 15 3.4.4 Structural Deform ations ..................................................................... 15 3.4.4.1 Fuel Storage Seism ic Qualification ................................... 16 3.5 Fuel Channel and Fastener .............................................................................. 17 3.5.1 Design Criteria for Norm al Operation ................................................ 17 3.5.2 Design Criteria for Accident Conditions ............................................ 18 4.0 Mechanical Testing ...................................................................................................... 25 4.1 Fuel Assem bly Axial Load Test ....................................................................... 25 4.2 Spacer Grid Lateral Im pact Strength Test ....................................................... 25 4.3 Tie Plate Strength Tests .................................................................................. 26 4.4 Debris Filter Efficiency Test ........................................................................... 27 4.5 Fuel Assem bly Fretting Test ............................................................................ 27 4.6 Fuel Assem bly Static Lateral Deflection Test ................................................. 27 AREVA NP Inc.
Gontrollea AREVA NP Uocument ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page iii 4.7 Fuel Assem bly Lateral Vibration Tests ........................................................... 27 4.8 Fuel Assem bly Im pact Tests ........................................................................... 28 5.0 Conclusion ...................................................................................................................... 28 6.0 References ...................................................................................................................... 29 Appendix A Illustrations .................................................................................................... 30 AREVA NP Inc.
L;ontrolled AREVA NP Uocument ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page iv Tables Table 2-1 Fuel Assembly and Component Description ............................................................ 7 Table 2-2 Fuel Channel and Fastener Description .................................................................. 8 Table 3-1 Results for ATRIUM 1OXM Fuel Assembly ............................................................ 19 Table 3-2 Results for Advanced Fuel Channel ...................................................................... 22 Table 3-3 Results for Channel Fastener ................................................................................ 24 Figures Figure A-1 ATRIUM 1OXM Fuel Assem bly ........................................................................... 31 Figure A-2 UTP with Locking Hardware ................................................................................ 32 Figure A-3 Im proved FUELG UARD LTP ............................................................................... 33 Figure A-4 ATRIUM 1OXM ULTRAFLOW Spacer G rid ......................................................... 34 Figure A-5 Full and Part-Length Fuel Rods ........................................................................... 35 Figure A-6 Advanced Fuel Channel ...................................................................................... 36 Figure A-7 Fuel Channel Fastener Assem bly ....................................................................... 37 This document contains a total of 45 pages.
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uontronled uocument AREVA NP ANP-31 19NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page v Nomenclature Acronym Definition AFC Advanced fuel channel AOO Anticipated operational occurrences ASME American Society of Mechanical Engineers B&PV Boiler and pressure vessel BWR Boiling water reactor CRDA Control rod drop accident EOL End of life HDSFSR High density spent fuel storage racks 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 NP Inc.
uontroiiea uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM T M 1OXM Fuel Assemblies Page 1 1.0 Introduction This report provides a design description, mechanical design criteria, fuel structural analysis results, and test results for the ATRIUMTM* 1OXM fuel assembly and 100/75 Advanced Fuel Channel (AFC) designs supplied by AREVA NP Inc. (AREVA) for use at the Monticello nuclear generating plant beginning with Cycle 28.
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 1OXM fuel at Monticello in a cycle specific compliance document.
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 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 54 MWd/kgU (Reference 3).
ATRIUM is a trademark of AREVA NP Inc.
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uontroiiea uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 10XM Fuel Assemblies Page 2 2.0 Design Description This report documents the structural evaluation of the ATRIUM 1OXM 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 Overview This ATRIUM 1OXM fuel bundle geometry consists of a 10x10 fuel lattice with a square internal water channel that displaces a 3x3 array of rods.
Table 2-1 lists the key design parameters of the ATRIUM 1OXM fuel assembly.
2.2 Fuel Assembly The ATRIUM 1OXM fuel assembly consists of a lower tie plate (LTP) and upper tie plate (UTP),
91 fuel rods, 9 spacer grids, a central water channel with [ ], and miscellaneous assembly hardware. Of the 91 fuel rods, 12 are PLFRs. The structural members of the fuel assembly include the tie plates, spacer grids, water channel, and connecting hardware. The structural connection between the LTP and UTP is provided by the central water channel. The lowest of the nine spacer grids is located just above the LTP to restrain the lower ends of the fuel rods.
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 the appendix.
2.2.1 Spacer Grid AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 3
[
Table 2-1 lists the main spacer grid attributes, and an illustration of the spacer grid is provided in the appendix.
2.2.2 Water Channel 1.
Table 2-1 lists the main water channel attributes and the appendix provides an illustration of a section of the water channel.
2.2.3 Lower Tie Plate
[
I t FUELGUARD is a trademark of AREVA NP Inc.
AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 4
[
The appendix provides an illustration of the LTP.
2.2.4 Upper Tie Plate and Connectinq Hardware
[
The appendix provides an illustration of the UTP and locking components.
AREVA NP Inc.
Lontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM T M 1OXM Fuel Assemblies Page 5 2.2.5 Fuel Rods
[
1.
Table 2-1 lists the main fuel rod attributes, and the appendix provides an illustration of the full length and part length fuel rods.
2.3 Fuel Channel and Components
[
I AREVA NP Inc.
Uontroiied Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Paqe 6
[
I.
Table 2-2 lists the fuel channel component attributes. The fuel channel and fuel channel fastener are depicted in the appendix.
AREVA NP Inc.
Uontrolled AREVA NP Uocument ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 7 Table 2-1 Fuel Assembly and Component Description
______________________________________________________ t_______
__________________________________________________________________________ ]
AREVA NP Inc.
Uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 8 Table 2-2 Fuel Channel and Fastener Description
[
i
]
AREVA NP Inc.
Uontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 9 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 will be documented in the Monticello fuel rod thermal-mechanical report.
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uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 10 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 techniques-often 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 usesSection III 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.
AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 11 I
See Table 3-1 for results from the component strength evaluations.
3.3.2 Fatigue Fatigue of structural components is generally [
3.3.3 Frettinq Wear Fuel rod failures due to grid-to-rod fretting shall not occur. [
I.
Fretting wear is evaluated by testing, as described in Section 4.5. The testing is conducted by I
]. The inspection measurements for wear are documented. The lack of significant wear demonstrates adequate rod restraint geometry at the contact locations. Also, the lack of significant wear at the spacer cell locations, relaxed to end of life (EOL) conditions, provides further assurance that no significant fretting will occur at higher exposure levels.
[
] and has operated successfully without incidence of grid-to-rod fretting in more than 20,000 fuel assemblies.
3.3.4 Oxidation, Hvdridina. and Crud Buildup Because of the low amount of corrosion on fuel assembly structural components, [
]
AREVA NP Inc.
uontrollea Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM 1OXM Fuel Assemblies M
T Page 12
[
I.
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 [
I.
Rod bow is calculated using the approved model described in Reference 4. The model has been shown to be conservative for application to the ATRIUM-10 fuel design. Less rod bow is predicted for the ATRIUM 1 OXM compared to the ATRIUM-1 0 due to a larger diameter fuel rod and a reduced distance between most spacer grids. [
]. 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 1OXM 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)
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.
AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 13 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 will be addressed in the Monticello fuel rod thermal-mechanical report.
3.3.8 Assembly Lift-off Fuel assembly lift-off is evaluated under both normal operating conditions (including ACOs) 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.
For faulted conditions, [
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Uontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 14
[ ]. 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 Monticello fuel rod thermal-mechanical report.
3.3.10 Miscellaneous Component Criteria 3.3.10.1 Compression Spring Forces The ATRIUM 1OXM 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.
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 AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 15 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 The LOCA evaluation is addressed in the Monticello LOCA MAPLHGR analysis for ATRIUM 1OXM fuel report.
3.4.2 Violent Expulsion of Fuel Results for the CRDA analysis are presented in the Monticello ATRIUM 1OXM fuel transition report and the subsequent cycle-specific Monticello reload licensing report.
3.4.3 Fuel Ballooning The LOCA evaluation is addressed in the Monticello LOCA MAPLHGR analysis for ATRIUM 1OXM fuel report.
3.4.4 Structural Deformations Deformations or stresses from postulated accidents are limited according to requirements contained in the ASME B&PV Code,Section III, Division 1, Appendix F, and SRP Section 4.2, Appendix A. The limits for each ATRIUM 1OXM structural component are derived from analyses and/or component load tests.
Testing is performed 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 AREVA NP Inc.
uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 16 as inputs for analytical models of the fuel assembly and fuel channel. [
]. See Section 4.0 for descriptions of the testing.
The methodology for analyzing the channeled fuel assembly under the influence of accident loads is described in Reference 2. Evaluations performed for the fuel under accident loadings include mechanical fracturing of the fuel rod cladding, assembly structural integrity, and fuel assembly liftoff.
I Assembly liftoff under accident conditions is described in Section 3.3.8.
3.4.4.1 Fuel Storage Seismic Qualification The High Density Spent Fuel Storage Racks (HDSFSR) analysis accounts for the fuel as added mass in calculating the structural integrity under postulated seismic loads. The weights of legacy fuel assembly designs at Monticello encompass the weight of the ATRIUM 1OXM fuel design. Therefore, the HDSFSR remains qualified with the introduction of the ATRIUM 1OXM fuel design.
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Lontrolied Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 17 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 AQOs, 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. The cyclic duty from pressure fluctuations is limited to less than the fatigue lifetime of the fuel channel. The fatigue life is based on the O'Donnel and Langer curve (see Reference 5), which includes a factor of 2 on stress amplitude or a factor of 20 on the number of cycles, whichever is more conservative.
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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Uontrolled Uocument AREVA NP ANP-3119NP Mechanical. Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 18 1.
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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(Jontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies PaQe 19 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 The ASME B&PV Code I limits on assembly Section III is used to components 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.
e Water channel I I 3.3.2 Fatigue I
[
I.
3.3.3 Fretting wear I Oxidation, hydriding, and 3.3.4 I [
crud buildup . .
3.3.5 Rod bow Protect thermal limits C (Table continued on next page)
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uontrolled Document AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 20 Table 3-1 Results for ATRIUM IOXM Fuel Assembly (Continued)
Criteria Section Description Criteria Results 3.3 Fuel System Criteria (Continued) 3.3.6 Axial irradiation growth
" Upper end cap Clearance always exists [
clearance
- Seal spring Remains engaged with [
engagement channel .
3.3.7 Rod internal pressure N/A Not covered in structural report 3.3.8 Assembly liftoff
[
- Normal operation No liftoff from fuel support (including AQOs) 1.
" Postulated No disengagement from fuel accident support. No liftoff from fuel support.
3.3.9 Fuel assembly handling [ [
3.3.10 Miscellaneous components 3.3.10.1 Compression spring Support weight of UTP and The design criteria are met.
forces fuel channel throughout design life 3.3.10.2 LTP seal spring Accommodate fuel channel The design criteria are met.
deformation, adequate corrosion, and withstand operating stresses (Table continued on next page)
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Uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 21 Table 3-1 Results for ATRIUM 1OXM 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 See results below for and ability to insert control individual components.
blades. SRP 4.2, App. A, and [
ASME Section III, App. F.
].
Fuel rod stresses [ I
] [
Spacer grid lateral [
load ] C Water channel load [
I.
UTP lateral load [ C ]
]
LTP lateral load C [ I I
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uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 22 Table 3-2 Results for Advanced Fuel Channel Criteria Section Description Criteria Results 3.5.1 Advanced Fuel Channel - Normal Operation Stress due to The pressure load including AOO The deformation during AOO pressure differential is limited to [ remains within functional limits
] according for normal control blade to ASME B&PV Code, Section II1. operation and the collapse load The pressure load is also limited requirement is met with [
such that [ ]. There is no significant plastic deformation during normal operation [
1.
Fatigue Cumulative cyclic loading to be Expected number of cycles less than the design cyclic fatigue [ ] is less than life for Zircaloy. [ allowable.
Oxidation and Oxidation shall be accounted for The maximum expected hydriding in the stress and fatigue analyses oxidation is low in relation to the wall thickness. Oxidation was accounted in the stress and fatigue analyses.
Long-term Bulge and bow shall not interfere Margin to a stuck control blade deformation (bulge with free movement of the control remains positive.
creep and bow) blade (Table continued on next page)
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Uontroiiea Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 23 Table 3-2 Results for Advanced Fuel Channel (Continued)
Criteria Section Description Criteria Results 3.5.2 Advanced Fuel Channel - Accident Conditions Fuel channel The pressure load is limited to The deformation during stresses and load [ blowdown does not interfere limit ] according to ASME B&PV with control blade insertion [
Code,Section III, App. F. The pressure load is also limited such that [
1.
Channel bending Allowable bending moment from combined based on ASME Code, horizontal Section III, Appendix F plastic excitations analysis collapse load 1.
Fuel channel gusset ASME allowable load rating of strength one gusset is [
______________________].
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uontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 24 Table 3-3 Results for Channel Fastener Criteria Section Description Criteria Results 3.5 Channel Fastener Compatibility Spring height must extend to All compatibility requirements the middle of the control cell to are met. The spring will extend ensure contact with adjacent beyond the cell mid-line.
spring.
Spring axial location must be The axial location of the spring sufficient to ensure alignment flat will always be in contact with adjacent spring at all with an adjacent spring; even if exposures. a fresh ATRIUM 1OXM is placed adjacent to an EOL co-resident assembly.
Strength Spring must meet ASME All ASME stress criteria are met stress criteria and not yield for the spring and cap screw.
beyond functional limit. In addition, the spring will not yield under the maximum Cap screw must meet ASME deflection.
criteria for threaded fastener.
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(uontroIlea uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM IOXM Fuel Assemblies Page 25 4.0 Mechanical Testing Prototype testing is an essential element of AREVA's 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 LateralImpact Strength Test Spacer grid impact strength was determined by a [
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Uontrolied Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM T M 1OXM Fuel Assemblies Paqe 26
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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, a lateral load test is performed on the UTP and LTP, and a compressive load test is performed on the LTP.
The UTP lateral load test was conducted on a test machine which applied an increasing load until a measurable amount of plastic deformation was detected. This provides a limiting lateral load for accident conditions. [
1.
For the Improved FUELGUARD LTP compressive load test, the tie plate was supported by the nozzle to simulate the fuel support conditions. A uniform, compressive axial load was applied to the grid. [
1.
To determine a limiting lateral load for accident conditions, the LTP lateral load test was conducted by attaching the grid of the tie plate to a rigid vertical plate and applying a side load to the cylindrical part of the nozzle. [
].
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luontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 27 4.4 Debris FilterEfficiency Test Debris filtering tests were performed for the Improved FUELGUARD lower tie plate to evaluate its debris filtering efficiency. These tests evaluated the ability of the Improved FUELGUARD to protect the fuel rod array from a wide set of debris forms. In particular, testing was performed using small filamentary debris (e.g., wire brush debris) as this form is known to be a cause of debris fretting fuel failures. When testing the small filamentary debris forms, the debris filter is placed in a hydraulic test loop above a debris chamber. After insertion of a debris set in the debris chamber, the loop pump is started to circulate water in the loop for a given amount of time. Multiple pump shutdowns and restarts are then simulated. At the end of the test, the location of all debris is recorded and the filtering efficiency is determined. These debris filtering tests demonstrate that the Improved FUELGUARD 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 1OXM fuel rod support design. Spacer springs were relaxed in selected locations to simulate irradiation relaxation. [
]. After the test, the assembly was inspected for signs of fretting wear. No significant wear was found on fuel rods in contact with spacer springs relaxed to EOL conditions. The results agree with past test results on BWR designs where no noticeable wear was found on the fuel rods or other interfacing components following exposure to coolant flow conditions.
4.6 Fuel Assembly Static LateralDeflection 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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uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 28 The test setup for the free vibration test is similar to the lateral deflection test described above.
The fuel assembly is deflected to a specific displacement and then released. Displacement data are recorded at several spacer locations. The assembly natural frequencies and damping ratios are derived from the recorded motion. The test is repeated for several initial displacements.
The forced vibration testing [
I.
4.8 Fuel Assembly Impact Tests Impact testing was performed in a similar manner to the lateral deflection test. The unchanneled assembly is supported in a vertical position with both ends fixed. The assembly is displaced a specified amount and then released. A load cell is fixed to a rigid structure and located adjacent to a mid-assembly spacer. The fuel assembly impacts the load cell and the resulting impact force is recorded as a function of the initial displacement. The measured impact loads are used in establishing the spacer grid stiffness.
5.0 Conclusion The fuel assembly and channel meet all the mechanical design requirements identified in References 1 and 2. Additionally, the fuel assembly and channel meet the mechanical compatibility requirements for use in Monticello. This includes compatibility with both co-resident fuel and the reactor core internals.
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uontrolled Uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 29 6.0 References
- 1. ANF-89-98(P)(A) Revision 1 and Supplement 1, Generic Mechanical Design Criteriafor 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. O'Donnell 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 StructuralResponse 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 R. Adamson, R. B. "Effects of Thermomechanical Processing on In-Reactor Corrosion and Post-Irradiation Properties of Zircaloy-2",
Zirconium in the Nuclear Industry: Eleventh InternationalSymposium, 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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uontrolled uocument AREVA NP ANP-3119NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 30 Appendix A Illustrations The following table lists the fuel assembly and fuel channel component illustrations in this section:
Description Page ATRIUM 1OXM Fuel Assembly 31 UTP with Locking Hardware 32 Improved FUELGUARD LTP 33 ATRIUM 1OXM ULTRAFLOW Spacer Grid 34 Fuel and Part-Length Fuel Rods 35 Advanced Fuel Channel 36 Fuel Channel Fastener Assembly 37 These illustrations are for descriptive purpose only. Please refer to the current reload design package for product dimensions and specifications.
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(Jontroled Luocument AREVA NP ANP-31 19NP Mechanical Design Report for Revision 0 Monticello ATRIUM TM 1OXM Fuel Assemblies Page 31 fsjm 03 308 Figure A-1 ATRIUM 1OXM Fuel Assembly (not to scale)
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Figure A-2 UTP with Locking Hardware AREVA NP Inc.
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I Figure A-3 Improved FUELGUARD LTP AREVA NP Inc.
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I Figure A-4 ATRIUM 1OXM ULTRAFLOW Spacer Grid AREVA NP Inc.
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Figure A-5 Full and Part-Length Fuel Rods (not to scale)
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I Figure A-6 Advanced Fuel Channel AREVA NP Inc.
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Figure A-7 Fuel Channel Fastener Assembly AREVA NP Inc.