ML22158A276

060722 INLRPT-22-67296 ECAR-5644 Rev. 2_Part1

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INL/RPT-22-67296 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements May 2022 ECAR-5644

DISCLAIMER This information was prepared as an account of work sponsored by an agency of the U.S. Government. Neither the U.S. Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness, of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. References herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the U.S. Government or any agency thereof. The views

INLRPT-22-67296 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements ECAR-5644 May 2022 Idaho National Laboratory Idaho Falls, Idaho 83415 http://www.inl.gov Prepared for the U.S. Department of Energy Under DOE Idaho Operations Office Contract DE-AC07-05ID14517

Page intentionally left blank TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 1 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Effective Date Professional Engineers Stamp 05/02/2022

1. Does this ECAR involve a Safety SSC (see def. LWP-10200)? Yes N/A

2. Safety SSC Determination STC-000160, Rev. 4 Not required per LWP-10010 (2019)

Document ID Section 4.1, cc.

3. SSC ID USA/9330/AF-96

4. Project No. Docket No. 71-9330

5. Engineering Job (EJ) or N/A Engineering Change (EC)

No.

6. Building Various

7. Site Area ATR Complex

8. Objective / Purpose The purpose of this calculation is to establish the basis for shipping heavier LEU fuel elements and payloads in the Advanced Test Reactor Fresh Fuel Shipping Container (ATR FFSC) in support of the Office of Conversion's United States High Performance Research Reactor (USHPRR) Conversion Program.

The Department of Energy, National Nuclear Security Administration's (NNSA) Office of Material Management and Minimization (M3) mission is to convert, remove and dispose of vulnerable nuclear material located at civilian sites worldwide. As part of its mission, M3's Office of Conversion works around the world to convert research reactors and isotope production facilities to non-weapon usable nuclear material both domestically and abroad. In support of this effort, the Office of Conversion's USHPRR Conversion Program is working with the Idaho National Laboratory (INL) to develop and qualify new LEU fuels and technologies for use in the ATR, the Advanced Test Reactor Critical (ATRC) facility, High Flux Isotope Reactor (HFIR), National Bureau of Standards Reactor (NBSR),

Massachusetts Institute of Technology Reactor (MITR), and University of Missouri Research Reactor (MURR). The USHPRR Program has selected a monolithic uranium-molybdenum fuel plate design consisting of uranium-10 wt% molybdenum alloy (U-10Mo) foils clad in aluminum alloy 6061 as the best candidate for the USHPRR LEU fuel plates. These new fuels weigh substantially more than the currently authorized HEU version of the reactors fuels.

An initial investigation was performed and documented using finite element analysis methods to establish the groundwork and likelihood that the ATR FFSC could safely protect the new fuel element contents given the heavier weight. Those analyses were successful. This analysis was subsequently performed to show the qualitative results of the analysis and to establish a basis for qualifying the ATR FFSC for heavier payloads.

The ATR FFSC is a rectangular stainless-steel container used for shipping radioactive material. The container is described in the ATR FFSC Safety Analysis Report (SAR). Per the ATR FFSC SAR, the ATR FFSC is designated a Type AF-96 packaging per the definition of 10 CFR §71.4 and was originally designed to transport HEU reactor fuel elements for the ATR, the Advanced Test Reactor Critical (ATRC) Facility, the Massachusetts Institute of Technology Reactor (MITR), and the University of Missouri Research Reactor (MURR). The Department of Energy, National Nuclear

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 2 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Security Administrations (NNSA), Office of Material Management and Minimization (M3) is working with Idaho National Laboratory (INL) to develop and qualify new LEU fuels and technologies for use in the ATR, ATRC, MITR, and MURR reactors. The LEU fuel elements will weigh significantly more than the current HEU designs and, combined with their associated fuel-handling enclosures for packaging, some configurations will exceed the 50 lbf used in the ATR FFSC qualifying drop tests.

There are LEU versions of MITR, MURR, and ATR fuel elements. However, for this evaluation, drop analysis of the ATR FFSC with only the heavier ATR low enrichment (LOWE) fuel element is considered in this evaluation because the LOWE fuel element is the heaviest of the considered LEU fuel elements.

The ATR HEU fuel element and the ATR LOWE fuel element are identical in every design aspect except for the fuel meat inside the 19 fuel plates. The LEU fuel meats are made using a U-10Mo high-density foil rather than uranium dispersed in aluminum in the HEU fuel elements. The high density of the uranium in the LEU fuel meat increases the LOWE fuel element weight to just under 44 lbf (versus the 22.1 lbf weight of the tested ATR HEU fuel element). ATR fuel elements are placed in a thin-gauge aluminum weldment called a fuel-handling enclosure during packaging. The fuel-handling enclosure is used to cover and protect the element during loading and unloading operations. The ATR fuel-handling enclosure weighs about 15 lbf per the drawings in the ATR FFSC SAR, and the weight is accounted for in this evaluation.

Transporting the heavier LEU fuel elements require evaluation of two issues. The first is the effect of the increased mass of the LEU fuel elements on the survivability of the ATR FFSC package following the requisite drop qualifications. The second is the effect of the increased mass of the fuel plates on the fuel element during the same drops.

The ATR FFSC containing an ATR HEU fuel element in an ATR fuel-handling enclosure was physically dropped multiple times to qualify the container as a Type AF-96 package. The ATR FFSC SAR describes the drop tests performed with an actual ATR HEU fuel element weighing 22.1 lbf contained in a 14.3 lbf fuel-handling enclosure for a total payload of 36.4 lbf. Those drop tests showed that the ATR FFSC maintained containment of the ATR HEU fuel element and the fuel element was not significantly damaged. (Containment is not defined as leak tight, but as retention of the radioactive contents.)

Appendix A, Section A-2.0 of this evaluation provides a table containing a specific set of sequential drop scenarios requested to be performed by the USHPRR program in support of establishing the safety basis for the heavier payloads. This evaluation provides FEA results for that set of sequential drop scenarios. The drop scenarios include five drop scenarios with a LOWE fuel element investigating the conditions of the ATR FFSC and one drop scenario with an ATR HEU fuel element used to validate the result against the actual drops performed for the original container qualification.

Note that this report was done at the quality level necessary to be included in a nuclear-facility safety basis. This report describes the results of the FEA as related to the required drop scenarios.

Incorporation of the FEA into the safety basis will be evaluated by the ATR FFSC design authority.

FEA drops for the ATR FFSC are performed with nonlinear elastic/plastic evaluation. Suitability of the FEA drops for establishing a safety basis of the ATR FFSC are based on material rupture (i.e.,

through-thickness failure), gross deformation, and the ability of the ATR FFSC to retain the materials after the drops.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 3 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

9. If revision, please state the reason and list sections and/or page being affected.

Revision 1 is performed to make editorial changes throughout the document and update some of the finite element results.

Revision 2 involved clearly conveying, in Section B-2.1 of the report, the material model(s) used and which materials had the element deletion function activated. In addition, wording was added to Section 4.0 in the main body of the report to clearly convey the drawings used to model the ATR LOWE fuel element.

10. Conclusion / Recommendations The results of the ATR FFSC FEA benchmark test model are consistent with the similar physical drops documented in the ATR FFSC SAR. The FEA models for the remaining five drop scenarios show that the acceptance criteria are met.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 4 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements CONTENTS 1.0 PROJECT ROLES AND RESPONSIBILITIES............................................................................... 5 2.0 SCOPE AND BRIEF DESCRIPTION .............................................................................................6 3.0 DESIGN OR TECHNICAL PARAMETER INPUT AND SOURCES ............................................. 10 4.0 RESULTS OF LITERATURE SEARCHES AND OTHER BACKGROUND DATA ....................... 11 5.0 ASSUMPTIONS ...........................................................................................................................11 6.0 COMPUTER CODE VALIDATION ...............................................................................................12 7.0 DISCUSSION/ANALYSIS ............................................................................................................12

8.0 REFERENCES

.............................................................................................................................17 APPENDIXES

• Appendix A - Engineering Inputs

• Appendix B - Drop Analyses Models and Results

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 5 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 1.0 PROJECT ROLES AND RESPONSIBILITIES Pages Covered (if Project Role Name Organization applicable)

Performer R. E. Spears J212 Checkera K. D Ellis J212 See DCR: 695477 Independent Reviewerb S. K. Quirl J212 CUI Reviewerc R. Harwell J212 Managerd R. Harwell J212 Requestoref E. C. Woolstenhulme D230 Nuclear Safetyf A. L. Tam U740 Document Ownerf E. C. Woolstenhulme D230 Responsibilities:

a. Confirmation of completeness, mathematical accuracy, and correctness of data and appropriateness of assumptions.

b. Concurrence of method or approach. See definition, LWP-10106.

c. Concurrence with the documents markings in accordance with LWP-11202.

d. Concurrence of procedure compliance. Concurrence with method/approach and conclusion.

e. Authorizes the commencement of work of the engineering deliverable.

f. Concurrence with the documents assumptions and input information. See definition of Acceptance, LWP-10200.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 6 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 2.0 SCOPE AND BRIEF DESCRIPTION Figure 1 shows the evaluated ATR FFSC package (per the ATR FFSC SAR (2017), Figure 1.2-1). The Closure Handle Cover is used to prevent the use of the closure handle for tiedown purposes and is not considered in this evaluation. Figure 2 shows the fuel element and identifies some of its components.

(Lid)

Figure 1 - ATR FFSC package (per the ATR FFSC SAR (2017), Figure 1.2-1).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 7 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Top end box Fuel plates Side plate Comb Bottom end box Figure 2 - Fuel element.

Per Table 2.12.1.3 of the ATR FFSC SAR (2017), eleven consecutive drop tests were performed with an ATR FFSC containing an actual ATR HEU fuel element. These drop scenarios are shown in Table 1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 8 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 1 - List of physical drop tests Test No. Drop Impact Orientation Height 1.) CN1-1 4 ft. Center of gravity over the top corner.

2.) CD1-1 30 ft. Flat side drop with the pocket side down.

3.) CD2.A-1 30 ft. Flat side drop with the index lugs facing down.

4.) CD2.B-1 30 ft. Flat side drop with the index lugs facing down.

5.) CD3-1 30 ft. Flat side drop with pockets and index lugs on the sides (surface temperature approximately 13°F) 6.) CD4-1 30 ft. Vertical bottom drop (surface temperature approximately 41°F) 7.) CP3-1 40 in. Closure Assembly (referred to as the lid from this point further) over a 6 inch diameter puncture bar (attempting to cause rotation of the lid) 8.) CD5-1 30 ft. Center of gravity over the top corner.

9.) CD2.C-1 30 ft. Flat side drop with the index lugs facing down.

10.) CP2-1 40 in. Center of gravity over side and 30° off horizontal over a 6-inch diameter puncture bar 11.) CP1-1 40 in. Vertical top drop with the lid centered over a 6-inch diameter puncture bar As shown in Table 1, there is a temperature range that must be considered for the evaluated drops. Per ATR FFSC SAR (2017), Section 3.3.1.1, the maximum ambient air temperature that must be considered is 100°F, per 10 CFR §71.71(c)(1). The ATR FFSC SAR (2017), Section 2.6.1 notes that the maximum ATR FFSC package temperature under conditions of 100°F ambient temperature and full insolation is 186°F on the outer shell. Per ATR FFSC SAR (2017), Section 3.3.1.2, the minimum ambient air temperature that must be considered is -40°F, per 10 CFR §71.71(c)(2). The ATR FFSC SAR (2017), Section 2.6.2, notes that a minimum ambient temperature of -40°F can produce a minimum average package temperature of -40°F. Per ATR FFSC SAR (2017), Section 2.1.2.1.1, the minimum temperature considered for the evaluated drops is -20°F. Discussion relative to material properties for this temperature range is given in Appendix B, Section B-2.1. Also, the ATR FFSC SAR (2017), Section 2.6.1 notes that a potential maximum pressure rise of less than 4 psi is possible within the sealed cavity. This is not considered to be significant enough for inclusion in the drop scenarios.

Table 2 lists the drop scenarios considered in the scope of this evaluation (from Appendix A, Section A-2.0). Table 3 provides further clarification to relate which Table 1 drop scenarios are modeled to accommodate the Table 2 sequential drops.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 9 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 2 - List of FEA model-simulated drop tests (see Appendix A, Section A-2.0).

Test Weights* To Show: Mat. Props** Preceded by Followed by Benchmark Pkg: Table Model is reliable Pkg: actual CN1 None 2.12.1-1 Fuel: actual Fuel: 22.1 lb or min CD3 Pkg: Table Integrity of swage Pkg: max None CP1 2.1-1 Fuel: Min Fuel: 44 lb CD4 Integrity of swage Pkg: max None CP1 Fuel: Min CD5 Retention of Square tube: CN1 CP1 closure max Closure: min Fuel: min CD-New Integrity of pins Pkg: max None CP3 (10° Pins: min rotated) Fuel: min CD5 (soft) Maximum Pkg: min CN1 None deformation Fuel: min

• The referenced tables can be found in ATR FFSC SAR (2017)

• • Actual material properties are used where Pkg: actual or Pkg: max is used in the table (considering Pkg is the FFSC), see Appendix A, Section A-3.0. Relatively strong fuel element end boxes and ATR Fuel Handling Enclosure (referred to as the enclosure from here forward) are defined for the Benchmark test (to be closer to actual response) and the CD5 test (considering that it is conservative for retention of the closure evaluation). Otherwise, minimum material property values are used. Damage to the enclosure and end boxes is not a concern.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 10 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 3 - Table 1 impact tests being simulated to accommodate the Table 2 tests.

Table 2 Test Table 1 Impact test being simulated First Impact Second Impact Third Impact Benchmark CN1-1 CD5-1 N/A CD3 CD3-1 CP1-1 N/A CD4 CD4-1 CP1-1 N/A CD5 CN1-1 CD5-1 CP1-1 CD-NEW (10° CD2.A-1* CP3-1 N/A rotated)

CD5 (soft) CN1-1 CD5-1 N/A

• - This drop scenario is oriented to mimic the actual impact orientation for the actual drop. It is rotated about the long axis of the FFSC and the rotation angle is approximated based on the impact description and the observed damage in the actual drop. All other drop scenarios are modeled to match the desired impact orientation of the actual drop.

3.0 DESIGN OR TECHNICAL PARAMETER INPUT AND SOURCES

1. Natural Phenomena Hazard (NPH) category and source (Performance Category per DOE-STD-1021 and/or Seismic Design Category per ANSI/ANS 2.26): N/A

2. Design Requirements and Acceptance Criteria: The acceptance criteria are provided with the load scenarios defined in Table 2. Table 4 provides a list of criteria for this evaluation.

3. This work is performed in accordance with the applicable requirements of LWP-10000 (2021),

LWP-10106 (2021), and LWP-10200 (2021).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 11 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 4 - Criteria for the evaluation No. Criteria 1.) The Benchmark test is intended to establish model reliability. The FEA model is compared with similar actual drops documented in the ATR FFSC SAR (2017).

2.) The CD3 test is intended to show that the integrity of the swage is maintained in the LOWE fuel element for the defined sequential drop scenario. (The swaged joint attaches the fuel plates to the fuel element side plates.)

3.) The CD4 test is intended to show that the integrity of the swage is maintained in the LOWE fuel element for the defined sequential drop scenario. (The swaged joint attaches the fuel plates to the fuel element side plates.)

4.) The CD5 test is intended to show that the retention of the closure is maintained in the LOWE fuel element for the defined sequential drop scenario. For this model run, the pins and bayonets must remain competent and the lid body must not be breached.

5.) The CD-New (10° rotated) test is intended to show that the integrity of the pins is maintained for the defined sequential drop scenario. For this model run, the pins must remain competent enough to prevent lid rotation.

6.) The CD5 (soft) test is intended to show that maximum deformation in the FFSC for the defined sequential drop scenario. For this model run, the maximum deformation is established for the FFSC. Additionally, the competency of the FFSC to maintain fuel element containment is checked.

4.0 RESULTS OF LITERATURE SEARCHES AND OTHER BACKGROUND DATA For this evaluation, there are many documents that are referenced for specific information. The fundamental technical document used for this evaluation is the ATR FFSC SAR (2017) which includes all of the drawings needed to model the packaging. To model the ATR LOWE fuel element, the following drawings are used:

- INL Drawing 606255, ATR LEU (LOWE) End Box Details, Rev 1, 11/23/2020.

- INL Drawing 606256, ATR LEU (LOWE) Side Plate Details, Rev 1, 11/23/2020.

- INL Drawing 606257, ATR LEU (LOWE) Fuel Element Assembly, Rev 1, 11/23/2020.

- INL Drawing 606737, ATR LEU (LOWE) Fuel Plate Details, Rev 1, 11/23/2020.

Additionally, an initial investigation was performed and documented in INL/EXT-20-60209 (Spears 2021), Revision 1 using finite element analysis methods to establish the groundwork and likelihood that the ATR FFSC could safely protect the new fuel element contents given the heavier weight.

5.0 ASSUMPTIONS Assumptions used in the evaluation are stated and justified when employed. There are no assumptions employed that require post-analysis verification.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 12 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 6.0 COMPUTER CODE VALIDATION A. Computer type: Dell Latitude 7490 laptop and sawtooth which is an HPE SGI 8600 system (maintained by the High Performance Computing group)

B. Operating System and Version: Windows 10 Enterprise (INL610883) and CentOS 7.9.2009 operating system (kernel release: 3.10.0-1160.21.1.e17.x86_64 #1 SMP Tue Mar 16 18:28:22 UTC 2021)

C. Computer program name and revision: Mathcad (2015) and Abaqus (2021)

D. Inputs (may refer to an appendix): Not applicable E. Outputs (may refer to an appendix): Not applicable F. Evidence of, or reference to, computer program validation: Mathcad does not have a formal validation. However, the Mathcad calculations are validated by the technical checker in the review process as permitted by Appendix E of LWP-10200 (2021). For the Abaqus (2021) FEA software, the computer code validation is performed in Snow (2021).

G. Bases supporting application of the computer program to the specific physical problem:

Mathcad was specifically written to perform the types of calculations employed herein. Abaqus (2021) is well known and capable for nonlinear, dynamic problems as are performed in this evaluation.

7.0 DISCUSSION/ANALYSIS The ATR FFSC SAR (2017) describes a series of physical drop tests along with evaluation to show the acceptability of an ATR FFSC loaded with a standard ATR HEU fuel element. The purpose of this present evaluation is to perform FEA on the seven sequential drop scenarios shown in Table 2. The first sequential drop scenario is performed with a standard ATR HEU fuel element and is intended as model validation. The remaining five sequential drop scenarios are performed with a LOWE fuel element.

While the physical drop test data provided in ATR FFSC SAR (2017) is used for calibration of the FEA models in this evaluation, there are limitations to an exact comparison as listed below:

1.) Actual material properties (yield stress, ultimate stress, ultimate elongation, etc.) are not available for all the components of the dropped package. Some actual material properties are provided in Appendix A, Section A-3.0 for the FFSC. However, the remaining material properties are based on minimums provided in the ATR FFSC SAR (2017), ASTM A240 (2019), ASTM A269 (2019),

ASTM A276 (2017), ASTM A312 (2019), ASTM A479 (2019), ASTM A554 (2016), ASTM B209 (2019), ASTM F835 (2018), and Snow (2013). Also, as discussed under Table 2, secondary (relatively strong) fuel element end boxes are defined where warranted.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 13 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 2.) Exact impact orientations for the physical drops (listed in Table 1) are not known. Though the ATR FFSC SAR (2017) discussion gives some idea of how the physical impact orientation differed from that listed in Table 1, the exact physical impact orientations are not documented. For the orientations in this evaluation, ideal orientations are run for most drop scenarios. However, the side drop that is oriented with an initial 10° rotation is given the rotation to better represent the actual impact orientation of the third actual test (shown in Table 1).

3.) The eleven physical drops were performed sequentially with the same package. This is possible with FEA modeling but difficult and it is overly conservative. For this evaluation, the most sequential drops with the same FEA model is three (as shown in Table 2).

4.) Exact package geometry is not known for the dropped package. This is not considered a significant problem and nominal dimensions are used for the FEA model. Page 2-27 of the ATR FFSC SAR (2017) states that the ATR HEU fuel element used was a rejected production fuel element. However, the defects were considered cosmetic and not structurally significant for purposes of the certification tests. Page 2.12.1-2 of the ATR FFSC SAR (2017) says that the discrepancies between the tested ATR FFSC and the ATR FFSC drawings were minor and would not significantly affect the ATR FFSC during testing.

5.) When performing sequential impacts, the first impact is given exact parameters for impact. As the damaged components rebound from the first impact, their center-of-gravity translational velocities can easily be established. Using this information, accelerations can be applied based on the velocities to make the components motion become synchronized and heading toward the next impact with the proper velocity and direction. Also, based on nodal velocities at the same point in time, the angular velocity of the FFSC can be approximated and loads can be applied to stop the angular motion as gently as possible. Based on the position of the FFSC when its angular motion would be stopped, direction of acceleration and the position of the impacted surface can be defined. However, during the time when accelerations and loads are applied to prepare the loaded FFSC for the next impact, the components can interact with each other. This causes the sequential impacts to be approximate for the approach that is used in this evaluation. To ensure that reasonable accuracy is maintained; however, initial conditions results are documented and discussed for every impact.

Considering the limitations, the FEA models are not expected to exactly match the physical tests.

However, reasonable comparison is still expected.

When setting up the FEA model for the loaded ATR FFSC, the structural components were included.

Notable items that were not included were the neoprene in the enclosure. Also not included were the insulation and 0.015 inch thick sheet that contains the insulation in the ATR FFSC. This along with possible effects due to the limitations listed above resulted in small discrepancies in the modeled weight versus actual measured weight. Table 2.12.1-1 of the ATR FFSC SAR (2017) lists the actual component weights. These include a Body Assembly weighing 225.0 lbf, a Closure Assembly (lid) weighing 9.0 lbf, a Fuel Handling Enclosure (enclosure) weighing 14.3 lbf, and an ATR HEU fuel element weighing 22.1 lbf. To match the actual component weights, the component densities were adjusted as needed in the FEA model.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 14 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements In an actual ATR HEU fuel element, the fuel plates are attached to the side plates with a swaged joint.

Section 4.2.1.3.2 of SAR 153 (2012) states that the point of swage joint release is required to be greater than 150 lbf per linear inch of joint. For the ATR HEU fuel element model and the LOWE fuel element model, swaging is performed as part of the model runs. A detailed discussion of how the swage joints are modeled and calibrated can be found in Section B-2.2.

Appendices A and B provide the details of this evaluation. Appendix A provides engineering inputs.

These include the analysis plan, defined scope, and actual material properties used in the certification test unit described in the ATR FFSC SAR (2017). Appendix B provides the model development for all the models needed for the drop analyses listed in Table 2. The model development includes defining material properties (see Section B-2.1), calibrating the swaged connection in the fuel element (see Section B-2.2), defining initial conditions (see Section B-2.3), defining the process used to define sequential drop loads and accelerations (see Section B-2.4), defining the FEA models (see Section B-3.0), providing the FEA model results (see Section B-4.0), and providing abbreviated input files (see Section B-5.0). Using the Appendix B data along with the referenced documents, generation of a similar complete set of FEA models should be possible. Using the models developed in Appendix B, a complete set of model runs were performed per Table 2. A summary of the evaluation results is given in Table 5.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 15 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 5 - Summary of the evaluation results.

Section Model Test Sequence Purpose Results B-4.1 C.G. over top corner drop, Benchmark The accumulated deformation of the top including CN1 (four ft) and model corner in physical test was approx. 5/8 CD5 (30 ft) free drops inches. In model run, 0.833 inches, showing acceptable model performance.

B-4.2 Flat side drop (CD3, 30 ft) Demonstrate Swage integrity is maintained in test followed by closure end integrity of fuel sequence.

puncture (CP1) plate swage B-4.3 Flat bottom end drop (CD4, Demonstrate Swage integrity is maintained in test 30 ft) followed by closure integrity of fuel sequence.

end puncture (CP1) plate swage B-4.4 C.G. over top corner drop, Demonstrate Two of four bayonet lugs sheared off in including CN1 (four ft) retention of puncture impact, two other bayonet lugs followed by CD5 (30 ft) closure retained. Closure is retained.

concluding with closure end puncture (CP1)

B-4.5 Rotated side drop (CD-New, Demonstrate Pins damaged but remain functional; 30 ft) followed by oblique integrity of pins closure cannot rotate.

closure end puncture (CP3)

B-4.6 C.G. over top corner drop Demonstrate Closure bayonets and pins remain using minimum material maximum functional, fuel plate swages remain properties, including CN1 package intact.

(four ft) and CD5 (30 ft) free deformations drops For information, Table 6 provides FFSC maximum impact deceleration for all the modeled impacts. The center of gravity motion for the components is primarily tracked for use in the calculations for sequential impacts but is also used to track deceleration.

IAEA (2014), Section 701.9. provides guidance for selecting a cut-off frequency as a function of package mass for filtering acceleration data during impact. It says that for a loaded cask with a mass of 100 metric tonnes, the cut-off frequency should be 100-200 Hz. It goes on to say that for smaller packages with a mass of m metric tonnes, this cut-off frequency, is multiplied by a factor of (100/m)1/3.

Considering the loaded FFSC mass given in the ATR FFSC SAR (2017), Table 2.12.1-1 of 270 lb (0.123 metric tonnes), the guidance recommends a scale factor of 9.3. Using the 100 Hz cut-off frequency as reference, this translates to a minimum cut-off frequency of about 930*Hz. Considering that this represents the lower end of what is reasonable, a cut-off frequency of 1000 Hz is used in Table 6 as a reasonable value. Abaqus (2021) provides a butterworthFilter which is used to apply the cut-off frequency to the data.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 16 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table 6 - FFSC maximum Impact deceleration summary with a cut-off frequency of 1000 Hz.

Test FFSC Maximum Impact Deceleration (Impact Velocity)

• First Impact Second Impact Third Impact Benchmark 356 g (193 in/sec) 718 g (527 in/sec) N/A CD3 1661 g (527 in/sec) 745 g (176 in/sec) N/A CD4 1785 g (527 in/sec) 393 g (176 in/sec) N/A CD5 365 g (193 in/sec) 794 g (527 in/sec) 240 g (176 in/sec)

CD-NEW (10° 1387 g (527 in/sec) 54 g (176 in/sec) N/A rotated)

CD5 (soft) 278 g (193 in/sec) 640 g (527 in/sec) N/A

• - The decelerations are vertical in the impact frame of reference.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 17 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

8.0 REFERENCES

• Abaqus (2021). Abaqus Version 2021.HF6, Dassault Systmes Simulia Corp., 2021.

• ASME (2019). ASME Boiler & Pressure Vessel Code,Section II, Materials, Part D, Properties (Customary), 2019 Edition, The American Society of Mechanical Engineers, Two Park Avenue, New York, NY 10016 USA, July 2019.

• ASTM A240 (2019). ASTM A240/A240M19, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2019.

• ASTM A269 (2019). ASTM A269/A269M15a (Reapproved 2019), Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2019.

• ASTM A276 (2017). ASTM A276/A276M17, Standard Specification for Stainless Steel Bars and Shapes, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2017.

• ASTM A312 (2019). ASTM A312/A312M19, Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2019.

• ASTM A479 (2019). ASTM A479/A479M19, Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2019.

• ASTM A554 (2016). ASTM A55416, Standard Specification for Welded Stainless Steel Mechanical Tubing, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2016.

• ASTM B209 (2014). ASTM B20914, Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2019.

• ASTM F835 (2018). ASTM F83518, Standard Specification for Alloy Steel Socket Button and Flat Countersunk Head Cap Screws, ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, 2018.

• ATR FFSC SAR (2017). Advanced Test Reactor Fresh Fuel Shipping Container (ATR FFSC),

Safety Analysis Report (SAR), Docket 71-9330, Revision 14, AREVA Federal Services LLC, May 2017.

• IAEA (2014). Advisory Material for the IAEA Regulations for the Safe Transport of Radioactive Material (2012 Edition), IAEA Safety Standards for protecting people and the environment, Specific Safety Guide No. SSG-26, International Atomic Energy Agency, Vienna, 2014.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page 18 of 18 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

• LWP-10000 (2021). Engineering Initiation, Revision 13, Laboratory-wide Procedure, October 2021.

• LWP-10106 (2021). Engineering Verification, Revision 11, Laboratory-wide Procedure, April 2021.

• LWP-10200 (2021). Engineering Calculations and Analysis Report, Revision 12, Laboratory-wide Procedure, April 2021.

• LWP-10010 (2019). Use of Registered Professional Engineers, Revision 3, Laboratory-wide Procedure, November 2019.

• Mathcad (2015). Version 15.0 M040, Needham, MA: Parametric Technology Corporation, 2015.

• SAR-153 (2021), Upgraded Final Safety Analysis Report for the Advanced Test Reactor, Chapter 4, Reactor, SAR-153, Revision 25, Idaho National Laboratory, March 2021.

• Snow, S. D., (2013). RERTR Full-Size Element Assembly Structural Evaluation for ATR Vessel Loadings, ECAR-1482, Revision 1, Project File No.: 25228, June 2013.

• Snow, S. D., (2021). Software Validation Report for Abaqus Standard and Explicit Version 2021.HF6 for Structural Analyses, ECAR-5544, Revision 0, July 2021.

• Spears, R. E., (2021). Drop Analysis of the Advanced Test Reactor Fresh Fuel Shipping Container with Heavier Low-Enriched Uranium Fuel Contents, INL/EXT-20-60209, ECAR-5224, Revision 1, October 2021.

• Quirl, S. K., (2019). Weight of ATR Low Enriched (LOWE) Fuel Elements, TEV-3383, Revision 0, June 2019.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page A1 of A5 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Appendix A Engineering Inputs

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page A2 of A5 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements A-1.0 Analysis Plan

• Scope The purpose of this calculation is to establish the basis for shipping heavier LEU fuel elements and payloads in the Advanced Test Reactor Fresh Fuel Shipping Container (ATR FFSC) in support of the Office of Conversion's United States High Performance Research Reactor (USHPRR) Conversion Program.

The scope of this evaluation is to perform postulated sequential ATR FFSC drop scenarios (provided in Section A-2.0 of this appendix). These drop scenarios are requested by the USHPRR program in support of establishing the safety basis for the heavier payloads. The requested evaluation includes one drop scenario with an ATR HEU fuel element (for validation purposes) and five drop scenarios with a LOWE fuel element.

• Deliverables The deliverable is an ECAR that addresses the scope.

• Schedule Dependent on the success of the modeling progression.

• Assumptions Assumptions used in the evaluation will be stated and justified when employed.

• Safety/Non-Safety SSC This ECAR involves a Safety SSC.

Safety SSC Determination Document ID: STC-000160 SSC ID: USA/9330/AF-96 Project No.: Docket No. 71-9330

• Natural Phenomena Hazards criteria (if applicable)

N/A

• Load scenarios and acceptance criteria (if applicable)

This is a drop accident evaluation. Therefore, Natural Phenomena Hazard (NPH) doesnt apply. The load scenarios are defined in Section A-2.0 of this appendix.

The acceptance criteria are provided here for the load scenarios defined in Section A-2.0 of this appendix. Below is a list of criteria for this evaluation:

a. The Benchmark test is intended to establish model reliability. The FEA model is compared with similar actual drops documented in the ATR FFSC SAR.

b. The CD3 test is intended to show that the integrity of the swage is maintained in the LOWE fuel element for the defined sequential drop scenario. (The swaged joint attaches the fuel plates to the fuel element side plates.)

c. The CD4 test is intended to show that the integrity of the swage is maintained in the LOWE fuel element for the defined sequential drop scenario. (The swaged joint attaches the fuel plates to the fuel element side plates.)

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page A3 of A5 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

d. The CD5 test is intended to show that the retention of the closure is maintained in the LOWE fuel element for the defined sequential drop scenario. For this model run, the pins and bayonets must remain competent and the lid body must not be breached.

e. The CD-New (10° rotated) test is intended to show that the integrity of the pins is maintained for the defined sequential drop scenario. For this model run, the pins must remain competent enough to prevent lid rotation.

f. The CD5 (soft) test is intended to show that maximum deformation in the FFSC for the defined sequential drop scenario. For this model run, the maximum deformation is established for the FFSC. Additionally, the competency of the FFSC to maintain fuel element containment is checked.

• Verification/validation of calculation and analysis software (if applicable).

The Abaqus Version 2021.HF6 software used in the ECAR is validated with Snow, S. D., Software Validation Report for Abaqus Standard and Explicit Version 2021.HF6 for Structural Analyses, ECAR-5544, Revision 0, July 2021.

A-2.0 Defined Scope Below is the table defining the specific set of sequential drop scenarios and what results are to be shown in this evaluation. The defined scope was requested by the USHPRR program in support of establishing the safety basis for the heavier payloads:

Test Weights To Show: Mat. Props Preceded by Followed by Benchmark Pkg: Table Model is reliable Pkg: actual CN1 None 2.12.1-1 Fuel: actual or min Fuel: 22.1 lb CD3 Pkg: Table 2.1-1 Integrity of swage Pkg: max None CP1 Fuel: 44 lb Fuel: Min CD4 Integrity of swage Pkg: max None CP1 Fuel: Min CD5 Retention of Square tube: max CN1 CP1 closure Closure: min Fuel: min CD-New Integrity of pins Pkg: max None CP3 (10° Pins: min rotated) Fuel: min CD5 (soft) Maximum Pkg: min CN1 None deformation Fuel: min

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page A4 of A5 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements A-3.0 Actual Material Properties Below is the email providing the actual material properties for the tested ATR FFSC:

From: NOSS Philip (ORANO) <phil.noss@orano.group>

Sent: Monday, March 1, 2021 10:45 AM To: Eric C. Woolstenhulme <eric.woolstenhulme@inl.gov>

Cc: SMITH Richard (ORANO) <rich.smith@orano.group>; NOSS Philip (ORANO)

<phil.noss@orano.group>

Subject:

[EXTERNAL] Test Unit Actuals

Eric, Please pass on to Bob the following actual strength values taken from the data package for the ATR FFSC test units:

Item Yield, psi Ultimate, psi Elongation, %

Round inner tube 36,250 84,100 ---

Square outer tube 52,370 89,970 53 Top end plate 39,000 81,740 63 Bottom outer end plate 44,660 73,080 51 Bottom inner end plate 33,600 86,000 70 Closure body 44,500 88,000 60 I believe he should use these values in the benchmark run for the best chance of matching the test results.

Philip W. Noss Licensing Manager Orano Federal Services LLC 505 South 336th Street, Suite 400 Federal Way, WA 98003 253-552-1321 phil.noss@orano.group

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page A5 of A5 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements A-4.0 Aluminum-Aluminum Friction Aluminum-Aluminum friction: https://www.engineeringtoolbox.com/friction-coefficients-d_778.html:

Friction Coefficients for some Common Materials and Materials Combinations Frictional Coefficient Materials and Material Combinations Surface Conditions Static Kinetic (sliding)

- static - - sliding -

Aluminum Aluminum Clean and Dry 1.05 - 1.35 1.4

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B1 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Appendix B Drop Analyses Models and Results

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B2 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table of Contents B-1.0 Purpose/Summary ............................................................................................................ B2 B-2.0 Material Properties, Preloading, and Initial Conditions ...................................................... B2 B-3.0 Finite Element Models ..................................................................................................... B60 B-4.0 Finite Element Model Results.......................................................................................... B86 B-5.0 Abbreviated Input Files ................................................................................................. B168 (Note: References identified in this appendix can be found at the end of the main body.)

B-1.0 Purpose/Summary This appendix documents the finite element models development and results.

B-2.0 Material Properties, Swage Calibration, Initial Conditions, and Sequential Impacts The material properties are given in Section B-2.1. The swage calibration is defined in Section B-2.2. The initial conditions are defined in Section B-2.3. The approach used for sequential impacts is discussed in Section B-2.4.

B-2.1 Material Properties The materials used in this evaluation are summarized in Tables B-2.1-1 to B-2.1-10 and Sections B-2.1.1 to B-2.1.13. These material properties are defined to accommodate the FEA model-simulated drop tests given in the main body, Section 2.0, Table 2. Material properties are defined as an elastic-plastic bilinear model using Von Mises stress with isotropic strain hardening unless otherwise noted.

The temperature range considered for the ATR FFSC package is -40 to 186ºF (-20 to 186ºF for the evaluated drops). The ATR FFSC SAR (2017), Section 2.6.2, notes that a minimum ambient temperature of

-40ºF can produce a minimum average package temperature of -40ºF. The ATR FFSC SAR (2017), Section 2.6.1, notes that the maximum ATR FFSC package temperature under conditions of 100ºF ambient temperature and full insolation is 186°F on the outer shell. For this temperature range, the important material properties (i.e., modulus of elasticity, Poisson's ratio, density, yield stress, ultimate stress, and ultimate strain) do not change substantially. Additionally, ATR FFSC SAR (2017), Section 2.1.2.1.1, states that brittle fracture is not a concern for the ATR FFSC packaging. The ATR FFSC SAR (2017), Section 2.1.2.1.1, also states the performance of both the payload and packaging, including the reduced temperature tests, was satisfactory. Consequently, ambient-temperature material properties are used for drop scenarios of the full temperature range.

All elements, except the elastic steel puncture bar, have material properties with failure defined and element deletion used. The elements with defined failure are included in the analysis when its strains are less than the fracture strain (set to the ultimate plastic strain in Tables B-2.1 to B-2.1-10). When failure strain is reached, the element is removed from the analysis.

While Abaqus (2021) provides ways to include strain rate effects, they are not considered for this evaluation. This should be conservative because strain-rate effects give an apparent strengthening of the metals. If included, care would need to be used because the inertial aspect of the strain-rate strengthening is approximated already in the explicit solver.

Tables B-2.1-1 to B-2.1-10 show the material properties for each of the components.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B3 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Material Properties for the FFSC Body The main body, Section 2.0, Table 2 lists the FEA model-simulated drop tests and the material properties (Mat. Props) that should be used in them. Table B-2.1-1 material properties are used for the FFSC body where Pkg: min is identified in the main body, Section 2.0, Table 2. Table B-2.1-2 material properties are used for the FFSC body where Pkg: actual or Pkg: max is identified in the main body, Section 2.0, Table

2. Figure B-3.0-18 identifies the elements using the material properties in Table B-2.1-2. There are ASTM F835 (2018) screws in the FFSC body. Actual material properties were not provided for the ASTM F835 (2018) screws. Consequently, the minimum values are used for all drop scenarios.

Table B-2.1 Material properties used for the FFSC body where Pkg: min is identified.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

SST304BODY B-2.1.1 0.0007817(1) 28.3 0.31 30.03 97.50 0.259 F835 B-2.1.10 0.0007511 28.3 0.31 116.5 156.6 0.071 (1) This density is modified to cause the ATR FFSC body to weight 225 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

Table B-2.1 Material properties used for the FFSC body where Pkg: actual or Pkg: max is identified.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

ACTUAL_INN B-2.1.13 0.0007817(1) 28.3 0.31 36.30 128.67 0.421 ER_TUBE ACTUAL_OUT B-2.1.13 0.0007817(1) 28.3 0.31 52.47 137.65 0.420 ER_TUBE ACTUAL_TOP B-2.1.13 0.0007817(1) 28.3 0.31 39.05 133.24 0.484

_PLATE ACTUAL_BOT B-2.1.13 0.0007817(1) 28.3 0.31 44.73 110.35 0.408

_OUTER_PLT ACTUAL_BOT B-2.1.13 0.0007817(1) 28.3 0.31 33.64 146.20 0.525

_INNER_PLT F835 B-2.1.10 0.0007511 28.3 0.31 116.5 156.6 0.071 (1) This density is modified to cause the ATR FFSC body to weight 225 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B4 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Material Properties for the FFSC Lid and Pins The main body, Section 2.0, Table 2 lists the FEA model-simulated drop tests and the material properties (Mat. Props) that should be used in them. Table B-2.1-3 material properties are used for the FFSC lid and pins where Pkg: min is identified in the main body, Section 2.0, Table 2. Table B-2.1-4 material properties are used for the FFSC lid and pins where Pkg: actual or Pkg: max is identified in the main body, Section 2.0, Table 2. The pins are Nitronic 60. Actual material properties were not supplied for the Nitronic 60.

Consequently, the minimum values are used for all drop scenarios.

Table B-2.1 Material properties used for the FFSC lid and pins where Pkg: min is identified.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

SST304LID B-2.1.1 0.0007511(1) 28.3 0.31 30.03 97.50 0.259 NITRONIC_60 B-2.1.2 0.0007511 25.8 0.31 50.10 128.25 0.295 (1) This density is not modified because the ATR FFSC lid (closure assembly) weighs 9 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

Table B-2.1 Material properties used for the FFSC lid and pins where Pkg: actual or Pkg: max is identified.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

ACTUAL_LID_ B-2.1.13 0.0007511(1) 28.3 0.31 44.57 140.80 0.465 BODY NITRONIC_60 B-2.1.2 0.0007511 25.8 0.31 50.10 128.25 0.295 (1) This density is not modified because the ATR FFSC lid (closure assembly) weighs 9 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

Material Properties for the Enclosure The main body, Section 2.0, Table 2 lists the FEA model-simulated drop tests and the material properties (Mat. Props) that should be used in them. Table B-2.1-5 material properties are used for the enclosure in the CD3, CD4, CD-New (10° rotated), and CD5 (soft) tests as identified in the main body, Section 2.0, Table

2. These are minimum material properties. Table B-2.1-6 material properties are used for the enclosure in the benchmark and CD5 tests as identified in the main body, Section 2.0, Table 2. Relatively tough material properties (high energy density) are used for the benchmark test to be closer to the actual response.

Relatively tough material properties are used for the CD5 test considering that it is conservative where retention of the closure is of concern. Actual material properties were not supplied for the enclosure.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B5 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table B-2.1 Material properties used for the enclosure in the CD3, CD4, CD-New (10° rotated), and CD5 (soft) tests.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

AL5052 B-2.1.8 0.000331(1) 10.3 0.33 23.05 34.41 0.101 AL5052THN B-2.1.7 0.000331(1) 10.3 0.33 23.05 33.17 0.064 AL5052W B-2.1.9 0.000331(1) 10.3 0.33 9.509 29.50 0.163 STEEL(2) B-2.1.1 0.0007511 28.3 0.31 30.03 97.50 0.259 (1) The enclosure density is modified to cause it to weight 14.3 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

(2) The material data for the spring plunger in the enclosure just says, steel corrosion resisting body.

Given that its failure is not important, its material will be approximated as 304 stainless steel.

Table B-2.1 Material properties used for the enclosure in the benchmark and CD5 tests.

Name in Section Mass Modulus of Poissons True True Ultimate the FEA Density Elasticity Ratio Yield Ultimate Plastic Model [lbf*sec2/in.4] [106*psi] Stress Stress Strain

[ksi] [ksi] [in./in.]

AL5052 B-2.1.12 0.000331(1) 10.3 0.33 28.08 38.94 0.162 AL5052THN B-2.1.12 0.000331(1) 10.3 0.33 28.08 38.94 0.162 AL5052W B-2.1.12 0.000331(1) 10.3 0.33 28.08 38.94 0.162 STEEL(2) B-2.1.1 0.0007511 28.3 0.31 30.03 97.50 0.259 (1) The enclosure density is modified to cause it to weight 14.3 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

(2) The material data for the spring plunger in the enclosure just says, steel corrosion resisting body.

Given that its failure is not important, its material will be approximated as 304 stainless steel.

Material Properties for the Fuel The main body, Section 2.0, Table 2 lists the FEA model-simulated drop tests and the material properties (Mat. Props) that should be used in them. Table B-2.1-7 material properties are used for the ATR HEU fuel element in the benchmark test as identified in the main body, Section 2.0, Table 2. Relatively tough material properties are used for the end boxes in the benchmark test to be closer to the actual response.

Table B-2.1-8 material properties are used for the LOWE fuel element in the CD3, CD4, CD-New (10° rotated), and CD5 (soft) tests as identified in the main body, Section 2.0, Table 2. These are minimum material properties. Table B-2.1-9 material properties are used for the LOWE fuel element in the CD5 test as identified in the main body, Section 2.0, Table 2. Relatively tough material properties are used in the end boxes for the CD5 test considering that it is conservative where retention of the closure is of concern.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B6 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The fuel element models are the same in the vicinity of the swage (discussed further in Section B-2.4).

Additionally, the material properties of the swage beams are the same. These swage beams are used for generating swaging (with material properties shown in Table B-2.2-1). The swaging process causes elastic waves in the fuel element which continue to reflect around during impact (which in reality would not exist at the time of impact). To dissipate a small amount of this energy in the highest frequencies (with the expectation of slightly helping model stability), a very small beta damping (10-7) is added to the end boxes (AL356 and AL356W) material properties. This does seem to make the models run with a little more stability (though not totally solving the problem) while having minimal effect on the model run otherwise.

This does reduce the stabile time step which make the run time a little longer.

Table B-2.1 Material properties used for the ATR HEU fuel element in the benchmark test.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

UALX_FUEL(2) B-2.1.4 0.0002585(1) 10.0 0.33 8.006 24.11 0.205 AL6061T6 B-2.1.3 0.0002538 10.0 0.33 35.12 52.65 0.152 AL6061W B-2.1.4 0.0002538 10.0 0.33 8.006 24.11 0.205 AL356 B-2.1.5 0.0002538 10.3 0.33 35.12(3) 52.65(3) 0.152(3)

AL356W B-2.1.6 0.0002538 10.3 0.33 8.006(4) 24.11(4) 0.205(4)

(1) The fuel plate density is modified to cause the fuel element to weight 22.1 lbf as defined in Table 2.12.1-1 in the ATR FFSC SAR (2017).

(2) Material properties representing the ATR fuel plates from the ATR FFSC SAR (2017).

(3) With minimum material property values used for the AL356, unreasonably high damage resulted in the end boxes for the benchmark test. To produce more reasonable results, AL6061T6 material properties were used for the true yield stress, true ultimate stress, and ultimate plastic strain.

(4) With minimum material property values used for the AL356W, unreasonably high damage resulted in the end boxes for the benchmark test. To produce more reasonable results, AL6061T6W material properties were used for the true yield stress, true ultimate stress, and ultimate plastic strain.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B7 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table B-2.1 Material properties used for the LOWE fuel element in the CD3, CD4, CD-New (10° rotated), and CD5 (soft) tests.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

LOWE_FUEL(2) B-2.1.4 0.0006239(1) 10.0 0.33 8.006 24.11 0.205 AL6061T6 B-2.1.3 0.0002538 10.0 0.33 35.12 52.65 0.152 AL6061W B-2.1.4 0.0002538 10.0 0.33 8.006 24.11 0.205 AL356 B-2.1.5 0.0002538 10.3 0.33 18.03 25.75 0.027 AL356W B-2.1.6 0.0002538 10.3 0.33 9.509 22.77 0.032 (1) The fuel plate density is modified to cause the fuel element to weight 44 lbf as defined in Quirl (2019).

(2) Material properties representing LOWE fuel plates taken as the same as UALX_FUEL plates (except for density). The structural response of the LOWE fuel plates in compression, bending, and buckling under impact loads will be dominated by the thick aluminum covers and not the thin U-10Mo fuel layer.

Therefore, using the UALX_FUEL properties is justified.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B8 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table B-2.1 Material properties used for the LOWE fuel element in the CD5 test.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

LOWE_FUEL B-2.1.4 0.0006239(1) 10.0(2) 0.33(2) 8.006(2) 24.11(2) 0.205(2)

AL6061T6 B-2.1.3 0.0002538 10.0 0.33 35.12 52.65 0.152 AL6061W B-2.1.4 0.0002538 10.0 0.33 35.12(4) 52.65(3) 0.152(3)

AL356 B-2.1.5 0.0002538 10.3 0.33 35.12(4) 52.65(3) 0.152(3)

AL356W B-2.1.6 0.0002538 10.3 0.33 35.12(4) 52.65(3) 0.152(3)

(1) The fuel plate density is modified to cause the fuel element to weight 44 lbf as defined in Quirl (2019).

(2) Material properties representing LOWE fuel plates taken as the same as UALX_FUEL plates (except for density). The structural response of the LOWE fuel plates in compression, bending, and buckling under impact loads will be dominated by the thick aluminum covers and not the thin U-10Mo fuel layer.

Therefore, using the UALX_FUEL properties is justified.

(3) To produce conservatively high loads on the closure (which is the purpose of the CD5 test), relatively tough end box material properties are defined. This is achieved by defining AL6061T6 material properties for the true yield stress, true ultimate stress, and ultimate plastic strain in the AL6061W, AL356, and AL356W material properties.

Material Properties for the Steel Puncture Bar The steel puncture bar is simply modeled as being elastic with reasonable material properties values for carbon steel. These values are given in Table B-2.1-10.

Table B-2.1 Material properties used for the steel puncture bar.

Name in the Section Mass Modulus Poissons True True Ultimate FEA Model Density of Ratio Yield Ultimate Plastic

[lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [ksi] [ksi] [in./in.]

POST_STEEL B-2.1.11 0.000733 30.0 0.30 N/A N/A N/A

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B9 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.1Stainless Steel (304) Material Properties The modulus of elasticity, Poissons ratio, and mass density in this section are based on the ASME (2019).

The modulus of elasticity is from Material Group G values in Table TM-1. The Poissons ratio and mass density are from the 300 series values in Table PRD. The yield and ultimate stress values are from the ATR FFSC SAR (2017), Table 2.2-1. The ultimate strain is representative of values for ASTM A240 (2019),

ASTM A269 (2019), ASTM A479 (2019), and ASTM A554 (2016) Grade MT. The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

Note: The minimum engineering ultimate strain value is the minimum specified elongation for a two-inch specimen from the ASTM specifications referenced above.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B10 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.2 Stainless Steel Nitronic 60 (UNS S21800) Material Properties The modulus of elasticity, Poissons ratio, and mass density in this section are based on the ASME (2019).

The modulus of elasticity is from Material Group I values in Table TM-1. The Poissons ratio and mass density are from the 300 series values in Table PRD. The yield and ultimate stress values are from the ATR FFSC SAR (2017), Table 2.2-1. The ultimate strain is representative of values for ASTM A276 (2017).

The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B11 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.3 Aluminum (6061-T6 and -T651) Material Properties The material properties in this section are based on material property definition from Appendix A of Snow (2013). The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

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TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B13 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.4 Aluminum (6061-T0 and 6061-T6 weld) Material Properties The material properties in this section are based on material property definition from Appendix A of Snow (2013). The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B14 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.5 Cast Aluminum (A356.0-T71 or A356.0-T6) Material Properties The material properties in this section are based on material property definition from Appendix A of Snow (2013). The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B15 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.6 Cast Aluminum (356 weld) Material Properties The material properties in this section are based on material property definition from of Snow (2013),

Appendix A, Table A9. While all the data below did not appear to be available from Appendix A of Snow (2013), reasonable values are used to produce similar Abaqus material properties. [However, the 0.032 in/in true plastic strain is erroneously 6.7% higher than the 0.03 in/in value in Snow (2013). This difference was noticed after all the model runs were performed. Given the low yield and ultimate stress values and the relatively low volume of material, this difference does not represent a significant change in the energy to cause fuel element damage. Also, compared to the physical drops, the endbox and endbox welds model still appear to absorb significantly less energy than those in the physical drops. Consequently, this difference is not considered significant.]

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B16 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B17 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.7 Aluminum (5052-H32 Sheet) Material Properties The modulus of elasticity, Poissons ratio, and mass density in this section are based on Appendix A of Snow (2013) as being similar to 356 aluminum. The yield and ultimate stress values are from the ATR FFSC SAR (2017), Table 2.2-2. The ultimate strain is from ASTM B209 (2014) for specified thicknesses of 0.051 in. - 0.113in. The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B18 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.8 Aluminum (5052-H32 Plate) Material Properties The modulus of elasticity, Poissons ratio, and mass density in this section are based on Appendix A of Snow (2013) as being similar to 356 aluminum. The yield and ultimate stress values are from the ATR FFSC SAR (2017), Table 2.2-2. The ultimate strain is from ASTM B209 (2014) for specified thicknesses of 0.250in. - 0.499 in. The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B19 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.9 Aluminum (5052-O for Weld) Material Properties The modulus of elasticity, Poissons ratio, and mass density in this section are based on Appendix A of Snow (2013) as being similar to 356 aluminum. The yield and ultimate stress values and ultimate strain value are minimum values from ASTM B209 (2014) for specified thicknesses of 0.051 in. - 0.113 in. or 0.250in. - 3.000 in. The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B20 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B21 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.10 Enclosure 3/8-16UNC Screw Material Properties The tensile stress area for the screw is from ASTM F835 (2018). The modulus of elasticity, Poissons ratio, and mass density in this section are approximated as being similar to the 304 stainless steel properties already defined. The yield and ultimate stress values are from the ATR FFSC SAR (2017), Section 2.5.2.3.

The ultimate strain is representative of values for ASTM F835 (2018). The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B22 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.11 Steel Post Material Properties The steel post is simply modeled as being elastic with reasonable values for carbon steel. These values are approximately equal to those listed in the ASME (2019), Tables TM-1 and PRD. The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

B-2.1.12 Tough Aluminum (5052-H32) Material Properties Components of concern are the ATR FFSC body and lid and the fueled region of the fuel element.

Consequently, failure of the end boxes and enclosure does not ensure a conservative amount of damage to the components of concern. To address this, typical or conservatively tough values are used in the end

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B23 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements boxes and enclosure for some drop scenarios. The material properties below represent tough values and will be used for plate, sheet, and welds in the enclosure.

The modulus of elasticity, Poissons ratio, and mass density in this section are from Section B-2.1.7 of this calculation. The ultimate stress and elongation are from Clinton Aluminum & Stainless Steel (see attached data sheet in Appendix A). The conversion to true stress and true strain are done with equations from Abaqus (2018), Analysis Users Guide, Section 23.1.1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B24 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.1.13 Actual FFSC Material Properties Actual material properties have been provided by relative to the tested FFSC (see Appendix A, Section A-3.0). Figure B-3.0-18 shows the elements in the FFSC that use these material properties. The provided material properties include yield stress, ultimate stress, and elongation for six items in the FFSC (though elongation is not provided for one item). The remaining material properties (modulus of elasticity, Poissons ratio, and mass density) are based on the ASME (2019). The modulus of elasticity is from Material Group G values in Table TM-1. The Poissons ratio and mass density are from the 300 series values in Table PRD.

The conversion to true stress and true strain (shown below) are done with equations from Abaqus (2021),

Analysis Users Guide, Section 23.1.1.

Below are the provided actual material properties for the FFSC from Appendix A, Section A-3.0.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B25 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Elongation at failure for the round inner tube is not given. As an approximate value, the square outer tube value will be used:

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B26 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B27 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.2 Swage Calibration In an actual ATR HEU fuel element, the fuel plates are attached to the side plates with a swaged joint.

Section 4.2.1.3.2 of SAR-153 (2021) states that the point of swage joint release is required to be greater than 150 lbf per linear inch of joint. For the ATR HEU fuel element model and the LOWE fuel element model, the swage is approximated in the model. Figure B-2.2-1 shows the calibration model used to generate the swage parameters.

To model the swage, the initial geometry of the fuel element is defined so that the fuel plates are in (initially touching) frictional contact with the side plates. Next, swaging beams are added to the comb portions of the side plates (see Figures B-2.2-2 to B-2.2-3). In the model run time before impact occurs, a rapidly ramped (over 0.01 sec) temperature drop of 7000°F for the end plate swaging beams and 5000°F for the interior plate swaging beams is applied. This causes the swage beams to plasticly compress the comb portions of the side plates to produce swaging. Each swage beam cross section matches the cross section being compressed and the aluminum to aluminum coefficient of friction between the fuel plate and side plate is approximated as 1.2 per https://www.engineeringtoolbox.com/friction-coefficients-d_778.html (see attached table in Appendix A). (Note: The coefficient of friction is one of multiple calibration factors, so its exact value is not of high importance.) The swage beam material properties are defined with failure and the amplitude of the temperature is set high enough to fail the swage beams after they have produced the swage. Once failed, the swage beams play no further role in the stress/strain of the fuel element. The swage beams do have a small amount of mass (less than one pound) and it is considered in the fuel element mass. Considering this modeling approach, the swage beam material properties were iteratively modified to produce a reasonable swage (see Table B-2.2-1 for final material property values).

The partial model shown in Figure B-2.2-1 is generated with one side plate and the fuel plate ends that interact with it. Swaging is performed on all 19 of the fuel plates. Once swaging is complete, plates 1, 5, 10, 15, and 19 are pulled to produce pull-out loads for a representative sample of all 19 plates. The process is only repeated until the pull-out loads for all five fuel plates are between 125 lbf/in and 150 lbf/in (as shown in Figure B-2.2-4). Once achieve, the expectation is that all the plates will produce similar pull-out loads.

This produces a model where the fuel plates can be pulled out at a conservatively low load where the alternative of connecting the fuel plates to the side plate would have been overly strong. The plate pull-out did not turn out to be a significant factor in this evaluation. However, by including it, its contribution has been considered. (Note: The initial investigation produced slightly higher values for Table B-2.2-1.

Producing reasonable results, these values were initially used for all model runs. However, to ensure conservative results in the models specifically checking the swaged connection, further calibration was performed. The models specifically checking the swaged connection include CD3, CD4, and CD5 (soft) as shown in the main body, Section 2.0, Table 2. These three models have been rerun with the swage definition evaluated in this section.)

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B28 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Gaps considered in pullout load Figure B-2.2 Swage calibration mesh.

When establishing pullout load, the total load is gathered from the model results for each plate that is pulled out. To establish pullout load per inch, the total load is divided by the total plate length minus the length of the two gaps (where there is no swaging support).

The swage calibration mesh is generated with (C3D8I) linear brick elements and (B31) linear beam elements.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B29 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Fuel plates being pulled out (in the x-direction) for calibration Plate 1:

Plate 5:

Figure B-2.2 Zoomed view of the negative y-direction portion of the swage calibration mesh.

Considering Figure B-2.2-2, there are several defined boundary conditions for the swage calibration mesh.

First, x-direction translation is restrained for all the nodes on the negative x-direction (back) surface of the side plate. Second, y-direction translation is restrained for all the nodes on the negative y-direction surface (shown at the top of Figure B-2.2-2). Third, z-direction translation is restrained for all the nodes on the shared negative x-direction and negative z-direction edge. Finally, all the nodes at the free ends (positive x-direction) of the fuel plates being pulled are pinned. These nodes on the fuel plates are not allowed to translate while the swaging is applied. Once all of the swaging beams (identified in Figure B-2.2-3) have failed, the pinned nodes are displaced horizontally to pull the fuel plate out of the side plate. The pull direction is mostly in the x-direction. However, there is a slight y-direction component to pull parallel to the swaging slot. The pull progresses with an initial increase in load followed by a long, slowly decreasing load (as the plate is removed from the slot). Consequently, Figure B-2.2-4 shows only the initial part of the pull where the peak load is achieved. Additionally, the swaging process causes the pinned nodes to carry some compressive loading. It would be preferable for this to not occur. However, it is not considered to have a significant effect on the tensile pullout loads. Figure B-2.2-5 shows the swaged contact pressure in the side plate for the calibration mesh and the swage contact pressure for an unrestrained fuel element (from the CD3 model which is identified in the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B30 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Side plate heat affected zone (Welded 6061-T6 Aluminum)

Thinner end fuel plate swage beams Interior fuel plate swage beams Thicker end fuel plate swage beams Side plate (6061-T6 Aluminum)

Figure B-2.2 Swage calibration mesh materials.

The heat affected zone for aluminum welds in this evaluation is considered to occur within approximately one inch of a weld. The ATR FFSC SAR (2017) does not appear to consider heat affected zones.

However, physical drops are performed in the ATR FFSC SAR (2017) so heat affected zones have an influence even if they are not specifically recognized.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B31 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Table B-2.2 Material properties for swage beams.

Name Thermal Mass Modulus Poissons True True Ultimate Expansion Density of Ratio Yield Ultimate Plastic

[in./(in.*°F)] [lbf*sec2/in.4] Elasticity Stress Stress Strain

[106*psi] [psi] [psi] [in./in.]

FUSE(1) 0.00001 0.0002538 10.0 0.33 31000. 31001. 0.001 FUSE_THIN(2) 0.00001 0.0002538 10.0 0.33 48200. 48201. 0.001 FUSE_END(3) 0.00001 0.0002538 10.0 0.33 37500. 37501. 0.001 (1) Material properties for fuel plates 2 -18 swage beams.

(2) Material properties for fuel plate 1 swage beams.

(3) Material properties for fuel plate 19 swage beams.

Load Per Inch of Swage [lbf/in]

- Plate 1

- Plate 5

- Plate 10 Displacement [in]

Figure B-2.2 Swage pullout loads (for fuel element plates listed in Figure B-2.2-2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B32 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-2.2 Contact pressure at 0.01 sec in the side plates from the calibration mesh and from a mesh (for the CD3 drop scenario) used for evaluation.

Figure B-2.2-5 shows the contact pressure in the side plates from the calibration mesh and from a mesh used for CD3 (identified in the main body, Section 2.0, Table 2). The contact pressures are similar between the models with the calibration mesh showing a slightly higher maximum contact pressure. Given the similarity in the contact pressures in Figure B-2.2-5 and the margin for error shown in Figure B-2.2-4, this approach is considered adequate to model swaging in the models used for evaluation.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B33 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.3 Initial Conditions The initial conditions for the evaluation include initial velocity for the loaded ATR FFSC and temperature on the swaging beams. The initial temperature for all models where it is applicable, is 0°F. This has no relevance for material properties and temperature is only used to strain the swaging beams. Initial velocity, however, is not constant for all models. All the models are run with at least two impacts and swaging is required prior to the first impact. Consequently, the time required for swaging is accommodated by providing a gap (prior to impact) and reduced initial velocity for the loaded ATR FFSC. Considering the main body, Section 2.0, Table 2, there are three different drop heights. However, only the four foot and thirty-foot drop heights are required for the initial impacts (with swaging). Sections B-2.3.1 and B-2.3.2 provide initial velocity calculations for these two initial drop heights. Sequential impacts could have drop heights of thirty feet or forty inches. Since swaging only needs to occur initially, sequential impacts do not require adjustment to allow swaging. Sequential impacts are discussed further in Section B-2.4. For information, Sections B-2.3.3 to B-2.3.5 provide impact velocity calculations for four-foot, thirty-foot and forty inch drop heights.

The drop scenarios are all in air and gravitational acceleration is applied to all elements. Consequently, the following simple derivation is used for calculating initial conditions for the drop scenarios with swaging.

Calculations for the drop scenarios without swaging can be more simply performed using the energy calculation below.

B-2.3.1 Initial Conditions for a Four Foot Drop with Swaging The following derivation finds the initial velocity and initial gap for a drop scenario from four feet that includes time for swaging. The calibration model (see Section B-2.2) used a swaging time of 0.01 sec. To provide extra time to settle any local motion due to swaging, the time prior to impact (for swaging) is set to 0.015 seconds.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B34 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.3.2 Initial Conditions for a Thirty-Foot Drop with Swaging The following derivation finds the initial velocity and initial gap for a drop scenario from thirty feet that includes time for swaging. The calibration model (see Section B-2.2) used a swaging time of 0.01 sec. To provide extra time to settle any local motion due to swaging, the time prior to impact (for swaging) is set to 0.015 seconds.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B35 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.3.3 Impact Velocity for a Four Foot Drop The following derivation finds the initial velocity for a drop scenario from four feet.

B-2.3.4 Impact Velocity for a Thirty-Foot Drop The following derivation finds the initial velocity for a drop scenario from thirty feet.

B-2.3.5 Impact Velocity for a Forty Inch Drop The following derivation finds the initial velocity for a drop scenario from forty inches.

B-2.4 Sequential Impacts Considering the main body, Section 2.0, Table 2, sequential impacts are required for this evaluation. To perform this approach, the initial impact is run until rebound has occurred. Data from this point in the model run is used to figure out how to stop the rebound motion, how to accelerate the loaded FFSC for the next impact, and where to position the next impact surface to receive the sequential impact. Then the model is rerun to capture the two (or three) impacts.

If this process is performed in a series of model run steps, then contact can be modified in each step so that only the desired impact surface is in contact with loaded FFSC. This approach is used in all but the CD5

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B36 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements test (shown in the main body, Section 2.0, Table 2). This is the one scenario where three impacts are sequentially performed. This was initially run in three steps but it was becoming unstable as it transitioned to the third step. The second step causes a lot of damage to one end box and small end box pieces interacted with the fuel plates. It appeared that the instability occurred due to the difficultly for Abaqus (2021) to reestablish contact between fragments and fuel plates. Consequently, the second step was modified to accommodate two impacts. To do this, an acceleration was defined to move the second rigid surface out of the way after the second impact and before the third impact. This produced a stable model run.

When performing sequential impacts, the first impact is given exact parameters for impact. As the damaged components rebound from the first impact, their center-of-gravity translational velocities can easily be established. Using this information, accelerations can be applied based on the velocities to make the components motion become synchronized and heading toward the next impact with the proper velocity and direction. Also, based on nodal velocities at the same point in time, the angular velocity of the FFSC can be approximated and loads can be applied to stop the angular motion as gently as possible. Based on the position of the FFSC when its angular motion would be stopped; direction of acceleration and the position of the impacted surface can be defined. However, during the time when accelerations and loads are applied to prepare the loaded FFSC for the next impact, the components can interact with each other. This causes the sequential impacts to be approximate for the approach that is used in this evaluation.

The calculations in Sections B-2.4.1 to B-2.4.7 give an overview of how the loaded FFSC motion is modified with surface loads and accelerations to transition from one impact to the next. It also defines the position of successively impacted surfaces. The FFSC represents 80% of the loaded FFSC mass and in all but one of the drop scenarios, there is minimal angular motion upon rebound. Per the main body, Section 2.0, Table 2, the CD-New (10° rotated) test is the one model with significant angular motion but it is almost entirely along the axis of the FFSC. Consequently, surface loads are defined to stop the angular motion of just the FFSC with the expectation that minimal interaction with the enclosure and fuel will occur during the short period between impacts. Its important to note that while loads, accelerations, and positions are defined in this section, their accuracy/acceptability are judged based on the model results. Given the results, this approach appears to work acceptably well.

B-2.4.1 Subroutines Used for Evaluation There are several subroutines defined in Mathcad (2015) to aid in processing data. These are described and shown as follows:

The subroutine below generates a transform to rotate a given angle "" about the x-axes:

The subroutine "Ab_Tran_Rot" below performs the translation and then rotation used in Abaqus (2021) for initial orientation of instances. It uses the subroutines "Vec_to_Q" and "Rot_about_Vec." The subroutine "Vec_to_Q" accepts a direction vector "x". This vector acts as the transformed x-axis. Arbitrary but

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B37 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements orthogonal y- and z-axes are then generated to complete the transform. The subroutine "Rot_about_Vec" accepts a direction vector "v" which is to be rotated an angle "" about a vector "vec." The subroutine first generates the transform with the rotation vector "vec" being used for the x-axis. Next, the vector to be rotated "v" is transformed to the global axis, rotated about the global x-axis, and then transformed back (resulting in a rotation about the rotation vector "vec.") To orient an instance, Abaqus (2021) uses a translation vector "rtr" (which includes translations in the x-, y-, and z-directions) and a rotation vector "Rrot" (with seven values). The first three values and second three values are point vectors. The seventh value is the angle in degrees to rotate about the line going from the first point vector to the second point vector. The subroutine "Ab_Tran_Rot" uses that same approach as Abaqus (2021) to rotate a point vector "v." The subroutine first defines the rotation vector " vrot", rotation angle "", and a vector to a point on the line of rotation " ro". Next, the point vector is translated to " vtr". Finally, the translated point vector is moved to the line of rotation, rotated, and moved back completing the process.

The subroutine below accepts a rotation vector "Rrot" (with seven values) and generates and equivalent transform.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B38 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The subroutine below accepts a transform. Considering that the transform is equivalent to a rotation vector and angle of rotation, the subroutine outputs the equivalent rotation vector.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B39 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The subroutine below accepts two points for the model in an initial configuration and two points for the model in a final configuration. It then establishes the rotation angle "" and vector of rotation "vrot".

The subroutine below is to find an average rotation angle and vector of rotation for a set of nodes moving from an initial state to a deformed state (relative to the center-of-gravity of the component). It accepts initial nodal positions array "N1", final nodal positions array "N2", initial center-of-gravity "cg1", final center-of-gravity "cg2", acceptable distance between points being used "" and acceptable angle between points being used "". To establish the average rotation angle and vector of rotation, each node is paired with a second node. The paired node must be at least the distance "" away from the first node and form an angle with the first node relative to the center-of-gravity of at least "". Using the change in position of the two nodes about the center-of-gravity, a rotation angle and vector of rotation are established. This is repeated for every node in the nodal position arrays and an average rotation angle and vector of rotation are established.

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TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B41 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The subroutine below accepts a nodal position array "Ni", a nodal velocity array "Nv", a center-of-gravity vector "cgi", and the index i in the nodal arrays where the desired node occurs. A radius "r" is defined from the center-of-gravity to the selected node and the nodal velocity "v" is used to calculate the angular velocity of the node "".

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B42 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.4.2 FFSC Modeled Position Variables The loaded FFSC is positioned vertically for the base model. For any given Abaqus (2021) model, it is read in as an instance and positioned. For this configuration, the following definitions are needed.

Node 501458 Center-of-gravity B-2.4.3 Benchmark Test Initial Position For the benchmark test initial position, the Abaqus (2021) *INSTANCE translation and a rotation vectors are used from the input file 1_CN1_1_HEU.inp. The positioning is based on a theoretical corner. For this configuration, the following definitions are needed.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B43 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Center-of-gravity Node 501458

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B44 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.4.4 Benchmark Test First Impact Rebound Loads to Stop Angular Motion From the rebound results for the benchmark test first impact, the nodal displacements and velocities are exported for the body of the FFSC. Additionally, center-of-gravity acceleration, velocity, and displacement data is exported for the FFSC (variable name FFSC), the enclosure (variable name Encl), and the fuel element (variable name Fuel). The three center-of-gravity variables are organized in columns. The first column is time. The next three are x-, y-, and z-acceleration. The three after that are x-, y-, and z-velocity.

The final three are x-, y-, and z-displacement. Figures B-2.4.4-1 to B-2.4.4-3 show plots of the data. This data makes it possible to establish loads for stopping the angular motion of the FFSC.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B45 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 400

- x-direction 300 Acceleration [g]

- y-direction 200 100 0

100 0 0.01 0.02 0.03 100 Velocity [in/sec]

0 100 200 0 0.01 0.02 0.03 1

0 Displacement [in]

1 2

3 4

0 0.01 0.02 0.03 Time [sec]

Figure B-2.4.4 FFSC center-of-gravity motion.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B46 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 3

1.5x 10

- x-direction 3

1x 10 Acceleration [g]

- y-direction 500 0

500 0 0.01 0.02 0.03 200 100 Velocity [in/sec]

0 100 200 0 0.01 0.02 0.03 1

0 Displacement [in]

1 2

3 4

5 0 0.01 0.02 0.03 Time [sec]

Figure B-2.4.4 Enclosure center-of-gravity motion.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B47 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 400

- x-direction 300 Acceleration [g]

- y-direction 200 100 0

100 0 0.01 0.02 0.03 100 Velocity [in/sec]

0 100 200 0 0.01 0.02 0.03 1

0 Displacement [in]

1 2

3 4

5 0 0.01 0.02 0.03 Time [sec]

Figure B-2.4.4 Fuel center-of-gravity motion.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B48 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements For this configuration, the following definitions are needed.

This average angular velocity calculation seemed adequate for most of the drop scenarios. However, the results showed that it underestimated the angular velocity for the model having the most rotation (main

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B49 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements body, Section 2.0, Table 2, the CD-New (10° rotated) test). This was likely due to vibrations associated with the motion. As an alternative (to reduce the influence of local velocities), the rebound was run long enough to have two output frames spaced by 0.0025 seconds. The subroutine _vrot_av2 was then used to find the FFSC average rotation angle and vector of rotation from the added one to the final one. The average angle was then divided by 0.0025 seconds to produce the average angular velocity amplitude. This was multiplied by the average angle of rotation to produce an average angular velocity vector for the FFSC body.

Having the rebound angular acceleration, the FFSCs angular motion is stopped using the FFSC ribs (as shown in Figure B-2.4.4-4 and shown in more detail in Figure B-3.0-10). The ribs are used for this purpose because they are well placed and have minimal deformation in the impacts.

To stop rotation about the short axis To stop rotation of the FFSC, about the long shear loads axis of the FFSC, are applied to shear loads are the top and applied to the bottom faces outer faces on on the outer th ib Figure B-2.4.4 Fuel center-of-gravity motion.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B50 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The time for application of the impulse to stop FFSC angular motion is arbitrarily selected to be as short as possible. However, it needs to be long enough so that the loads to stop the angular motion dont get prohibitively large. Using a time of 0.01 seconds, all of the applied shear loads were less than 15 psi except one which was a little over 91 psi and used to stop the high axial rotation in the main body, Section 2.0, Table 2, the CD-New (10° rotated) test. These loads are considered reasonably low and not significant relative to adding damage to the model runs.

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TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B52 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B53 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.4.5 Benchmark Test Position Just Before the Second Impact After rebound, the loads from Section B-2.4.4 are applied to stop the angular motion of the FFSC. In this section, the angular position of the FFSC is established after it has been stopped. Also, the translational acceleration to stop the FFSC is established along with the translation position of the FFSC after it has been stopped. Finally, the translational acceleration to stop the enclosure and fuel element are established. The translational accelerations are body forces over an entire component. Consequently, the magnitude does not produce stresses in the component unless interaction with other components result. Where all the motion is stopped over the same time period, the differing acceleration on the different components should not encourage interaction.

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TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B55 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.4.6 Benchmark Test Position Acceleration for the Second Impact To achieve impact velocity for the second impact, a uniform acceleration is applied to the loaded FFSC in an appropriate direction to generate the right impact orientation. Because this is uniform, it can be superimposed over the loads and accelerations established in the previous two sections. Consequently, it is applied over the same 0.01 second interval. Also, being a uniform body force over all the loaded FFSC, the magnitude of the acceleration is not important because it does not cause stresses in the model.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B56 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The normal for the second impact surface points exactly opposite to the direction of the uniform acceleration. Consequently, the position of the second impact rigid surface will be evaluated in the section also.

To establish the uniform acceleration, the second impact velocity must be calculated:

If the impact velocity is produced in 0.01 seconds, the resulting acceleration and displacement can be calculated as follows:

Similar to the first impact, the second impact occurs along a line from the center-of-gravity to the same corner of the FFSC. Therefore, the direction of impact can be established as follows:

Considering the displacement to achieve the impact velocity (along with a 0.25-inch cushion), the point of impact on the second impact surface is calculated as followed:

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B57 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The y-direction normal vector for the rigid surface in the second impact is the negative of the above vector.

Consequently, the following transform can be defined for the rotation of the second impact surface:

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B58 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-2.4.7 Benchmark Test Summary of Important Values for the Second Impact:

Sections B-2.4.1 to B-2.4.6 provide the framework for how the sequential impacts are generated. The values listed below are the values that are included in the input file. A similar process occurred for each of the sequential impacts. Rather than including all that data, results will be shown to demonstrate that the sequential impacts occurred accurately.

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TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B60 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-3.0 Finite Element Models The FEA model meshes for this evaluation are shown in Figures B-3.0-1 to B-3.0-24. These meshes accommodate the list of FEA modeled tests in the main body, Section 2.0, Table 2.

The ATR FFSC body and lid are meshed continuously without special consideration of welding. This is due to the discussion in ATR FFSC SAR (2017), Section 1.2.1.1 shown below:

With the exception of several minor components, all steel used in the ATR FFSC packaging is of a Type 304 stainless steel. Components are joined using full-thickness fillet welds (i.e., fillet welds whose leg size is nominally equal to the lesser thickness of the parts joined) and full and partial penetration groove welds.

The enclosure and fuel element are modeled with consideration to welds. These components are mostly aluminum and elements within approximately an inch of a weld (i.e., the heat-affected zone) are meshed with welded material properties. For the enclosure, the end plates are only connected to the wall and door where skip welds are identified on the drawings.

For all models, general contact is defined with a friction coefficient of 0.1. Friction is not expected to play a large role in the impacts and frictional-energy dissipation tends to reduce the required energy absorbed in deformation, which could be unconservative. A friction coefficient of 0.1 is selected as a reasonable, yet relatively low value. For models where swaging is performed to secure the fuel plates, additional frictional contact is defined per the swaging calibration (see Section B2.2).

The boundary conditions for the models include having the rigid-surface reference node being fixed in all translation and rotation or, for models with the puncture bar instead of a rigid surface, having the nodes at the base of the puncture bar fixed in translation. (The puncture bar is a brick element, so no rotation degrees of freedom exist on the nodes).

To help ensure that the FEA models show conservative damage in the lid pins, a refined mesh (as shown in Figure B-3.0-17) is modeled. This mesh is used for the lid pins for drop scenarios where retention of the closure or the integrity of the lid pins is of primary concern.

The Abaqus (2021) solver used for all of the model runs is Abaqus/Explicit. This is an appropriate solver for impact analysis. The deformable elements for all of models in this evaluation include (C3D8I) linear brick elements, (S4R) linear shell elements, and (B31) linear beam elements. The rigid surface used in the models is a single (R3D4) rigid element. Each (B31) beam element is a simple beam element that is valid for Abaqus/Explicit model runs. The (S4R) shell elements are reduced integration shell elements that are recommended for Abaqus/Explicit model runs. The (C3D8I) brick elements are incompatible-mode elements. Per the Abaqus (2021), Analysis User's Guide, incompatible mode elements are first order elements that are enhanced by incompatible modes to improve their bending behavior. With the improved bending behavior noted by the Abaqus (2021), Analysis User's Guide, only one element through the thickness of a component is necessary to produce accurate bending behavior. It is further noted in Abaqus (2021) that the incompatible modes elements need to have an approximately rectangular shape for them to provide this second-order bending accuracy. The performance of trapezoidal-shaped incompatible mode elements is not much better than the performance of the regular, fully integrated, first-order interpolation elements. With these considerations, the brick element meshing is done with a focus on keeping the elements as rectangular as possible (especially where there is a need to capture bending with few elements through the wall thickness like in the fuel plates). Mesh in locations like in the pins preventing lid rotation are not as ideally rectangularly shaped. However, where the pin failure mode is primarily in shear, the incompatible mode elements still providing fully integrated, first order interpolation accuracy which should be sufficient for the potential shear failure.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B61 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements ATR FFSC Rigid surface Figure B-3.0 ATR FFSC and rigid surface mesh.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B62 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements ATR FFSC Closure Assembly (Lid)

ATR HEU Fuel Element Enclosure ATR FFSC Body Assembly Figure B-3.0 Cut-away of the ATR FFSC mesh.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B63 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements End Box (Cast Aluminum)

Comb and Comb Pins (6061-T6 Aluminum)

End Box Weld (Welded Cast Aluminum)

Side plate Weld (Welded 6061-T6 Aluminum)

Fuel plates (Fuel Aluminum)

Side plate (6061-T6 Aluminum)

Figure B-3.0 Fuel element mesh.

The fuel element mesh is continuously meshed through the end boxes, end box welds, side plate welds, and side plates. The fuel plates are swaged into the side plates (as defined in Section B-2.2). The combs are in contact with the fuel plates and the comb pins provide continuous attachment between the combs and fuel plates (as shown in Figures B-3.0-4 and B-3.0-5).

When defining element material properties for all aluminum items, welded properties were assigned to elements within approximately an inch of a weld location.

During swaging, elastic waves are produced as the swaging beams fail. It was suspected that these waves may play a role in model stability. As a way to provide a small amount of damping for the highest frequency waves, stiffness damping is defined (BETA=0.0000001) in only the end box and end box weld material properties. This very small damping value caused a smaller stable time step which extended run time several hours. However, it did appear to help some with stability (possibly just from the lowering of the stable time step).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B64 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Side plate, side plate heat affected zone, swage beams, and portion of fuel plates described in Section B-2.2 are meshed the same here.

The comb pins share nodes with the comb and, to help produce an efficient mesh, additional beams are used to attach and share nodes with a single layer of fuel plate nodes (as shown in Figure B-3.0-5).

Figure B-3.0 Zoomed view of the fuel element.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B65 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The red shows the comb pins connection.

Figure B-3.0 Comb and comb pins mesh.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B66 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Top and bottom end boxes.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B67 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Weld zone (5052-O Aluminum)

Spring plunger pin (Steel)

Enclosure wall (5052-H32 Sheet Aluminum)

Enclosure end plate (5052-H32 Plate Aluminum)

Enclosure door (5052-H32 Sheet Aluminum)

Figure B-3.0 Enclosure mesh.

The enclosure is mostly made up of shell elements. In general (for all components in the loaded ATR FFSC), the shell meshes are modeled on the center plane of the plate or sheet thickness and contact is considered based on the thickness of the shell. Also (for all components in the loaded ATR FFSC),

continuous attachment between shell and solid elements is achieved by extending the shells one layer into (or next to) the solid element mesh thereby producing moment bearing attachment.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B68 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Spring plunger Enclosure door Enclosure door hinge pin Shell elements passing through and sharing nodes with the end plate where welds occur Enclosure wall Figure B-3.0 Enclosure end with the end plate removed.

Figure B-3.0-8 shows the enclosure end with the end plate removed. In meshing the enclosure, the spring plunger pin is continuously attached to the enclosure door. The spring plunger pin fits through a hole in the enclosure end plate (see Figure B-3.0-7) and is in contact with it. The enclosure door hinge is meshed with brick elements. These brick elements are continuously attached to the door shell elements (that extend across the back of the brick elements in the figure). Then the nodes in one edge are shared with the enclosure wall shell elements. Because the nodes in the brick elements only have the three translational degrees of freedom, this attachment behaves as a hinge. The mesh at the opposing end of the enclosure is a mirror image of that shown in Figure B-3.0-8.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B69 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Index Lug Figure B-3.0 ATR FFSC Body Assembly.

The ATR FFSC Body Assembly is entirely 304 stainless steel except for the two screws which hold the index lugs in place. These screws are ASTM F835 (2018), 3/8-16UNC screws.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B70 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Ribs that are continuously attached to the inner pipe and in contact with the outer wall Figure B-3.0 Cut-away of the ATR FFSC Body Assembly with the outer wall removed.

The ATR FFSC Body Assembly is modeled as a continuous mesh throughout. The outer wall is continuously attached to the top on bottom plates. The ribs are continuously attached to the inner pipe but not the outer wall.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B71 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The tamper indicating device post is modeled with bricks that attach to nearby top plate nodes with beam elements The index lug is modeled as brick elements in contact with the outer wall Beam elements The pocket is (ASTM F835) continuously continuously attach meshed shell the Index Lug to the elements wall Figure B-3.0 Cut-away of the ATR FFSC Body Assembly top.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B72 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Shell 0.1874 in.

thick Shell 0.12 in.

thick Shell 0.375 in.

thick Shell 0.195 in.

thick Shell 0.185 in. thick Figure B-3.0 Cut-away of the ATR FFSC Body Assembly bottom.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B73 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Bayonet representing Pin preventing the lid the primary load path from rotation which could for the lid disengage the bayonets Figure B-3.0 Cut-away of the ATR FFSC Body Assembly and lid.

Figure B-3.0-13 shows how the lid interacts with the ATR FFSC Body Assembly. This shows that the bayonets are of primary importance for maintaining lid attachment. The lid pins are also important as lid pin failure could allow the lid to rotate and disengage without loading the bayonets.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B74 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The pin associated Closure handle with the tamper indicating device Closure handle screws Pin preventing lid rotation Bayonet Pin handle Lid body Figure B-3.0 Lid mesh.

Figure B-3.0-14 shows the full lid mesh. The closure handle is in contact with the body of the lid and is also continuously connected to the lid body through the closure handle screws. Considering Figure B-3.0-15, the lid pin and lid pin handle are in contact and are also continuously connected through the roll pin. The lid pin and lid pin handle are in contact with the lid body. The pin associated with the tamper indicating device is continuously meshed with the lid body.

The lid is entirely 304 stainless steel except for the two Nitronic 60 pins (which preventing lid rotation).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B75 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Roll pin connecting the pin to the pin handle Cavity with insulation (not modeled because it is nonstructural)

Figure B-3.0 Cut-away of the lid mesh.

Figure B-3.0-17 shows a fine meshed version of the lid pin that is used to show conservative damage where its damage is of primary concern. Its connection to the roll pin and interaction with the pin handle and lid are the same as that for the pin mesh shown in Figures B-3.0-14 and B-3.0-15.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B76 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Puncture bar mesh.

Per the ATR FFSC SAR (2017), Section 2.6.10, the puncture bar drops are based on the puncture bar described in §71.73(c)(3). Per the ATR FFSC SAR (2017), Section 2.12.1.2.2, the puncture bar that they used measured 6 in. in diameter and was 36 inches above the drop pad. The puncture bar is meshed 6 inches high with a 6-inch diameter and it has material properties of elastic steel. The short height and elastic material properties cause modeled puncture bar to be conservatively stiff relative to the actual puncture bar. However, the actual puncture bar is very stiff relative to the ATR FFSC package making this conservatism less significant.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B77 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Fine meshed for the lid pin.

Figure B-3.0-17 shows the fine meshed version of the lid pin. This version is used for the CD5, CD-New (10° rotated), and CD5 (soft) test drop scenarios (see the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B78 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements ACTUAL_TOP_PLATE F835 ACTUAL_INNER_TUBE ACTUAL_OUTER_TUBE NITRONIC_60 ACTUAL_LID_BODY ACTUAL_BOT_INNER_PLT ACTUAL_BOT_OUTER_PLT Figure B-3.0 Material property assignment for the FFSC models using actual material properties.

Figure B-3.0-18 shows the material property assignment for the FFSC models using actual material properties. The names used in Figure B-3.0-18 are material property names in the FEA model input files (identified with material properties in Tables B-2.1-2 and B-2.1-4).

Figures B-3.0-19 to B-3.0-24 show the evaluated models. Because swaging is applied initially for all the model runs, there is a significant gap before the first impact. The first impact surface lies in a horizontal plane. The second rigid surface or puncture bar for the second (or third) impact are positioned so that they are convenient for impact. The model runs are performed in two steps. During the first step, the first impact surface is in contact with the loaded FFSC and the second (and third) impact surface is not in contact with the loaded FFSC. During the second step, the first impact surface is not in contact with the loaded FFSC and the second (and third) impact surface is in contact with the loaded FFSC. Consequently, the loaded FFSC may overlap the second (or third) impact surface initially (as occurs in Figure B-3.0-21). The CD5 Test (see the main body, Section 2.0, Table 2) shown in Figure B-3.0-22 models three impacts. The first impact occurs in the first step and the next two occur in the second step. After the second impact, the second impact surface is moved out of the way for the third impact. This approach (rather than three steps) was adopted because it provided better model stability. It seemed that the large amount of end box damage in the second impact was making it difficult for reestablishing contact for the third.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B79 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the Benchmark Test (see the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B80 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the CD3 Test (see the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B81 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the CD4 Test (see the main body, Section 2.0, Table 2).

In Figure B-3.0-21, the loaded FFSC initially overlaps the puncture bar. However, there is not contact defined between them until after the first impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B82 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the CD5 Test (see the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B83 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the CD-New (10° rotated) Test (see the main body, Section 2.0, Table 2).

Upon impact, the physical drop test spun about the lengthwise axis of the package. The scuff marks in Figures 2.12.1-15 and 2.12.1-16 of the ATR FFSC SAR (2017) make it appear that impact first occurred near the edge. To best accommodate the description of the physical drop, an initial angle of 9.75° about the lengthwise axis of the package is defined to make the edge impact slightly before the index lugs in the FEA model.

The model shown in Figure B-3.0-23 is aligned so that the pins in the lid are nearly vertically oriented. In reality, there is a spring that holds them in place. But, this spring is not included in the model. During the first impact, the upper pin disengages from the FFSC body from inertia. This leaves the lower pin to carry all the angular loading of the first impact. For the second impact, the spring would have a chance to push the upper pin back in place (assuming that plastic deformation doesnt prevent it). To accommodate the opportunity for the upper pin to reengage the FFSC body, an approximately two-pound load is applied to push both pins outward (though this doesnt have any significant effect on the lower pin). This load is only applied during the 0.01 second time when loads and accelerations are applied to set up the second impact.

The amplitude of the load is sized to overcome the inertia of the pin (and pin handle) and move it back to its original position. Consequently, it will not move if it is no longer aligned well with the hole in the FFSC body.

(Note: During physical testing, momentary movement of the pins was not monitored. However, engagement of at least one locking pin after each test series was confirmed, and lid rotation did not occur.)

The calculation that follows is used to size the pin load.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B84 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B85 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-3.0 Mesh for the CD5 (soft) Test (see the main body, Section 2.0, Table 2).

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B86 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-4.0 Finite Element Model Results Sections B-4.1 - B-4.6 show the FEA model results for the sequential drop scenarios given in the main body, Section 2.0, Table 2. Each model run has two (or three) sequential impacts. Section B-2.3 provides an evaluation that defines initial conditions for the first impact considering that swaging is performed prior to impact. Section B-2.4 provides an example analysis for providing initial conditions for the second (or third) impact. For the second (or third) impact, the rebound motion from the first impact is gathered. The motion includes translational and angular motions. The translational velocities are gathered for the center-of-gravities of the FFSC, enclosure, and fuel element. With these translational velocities, appropriate accelerations can be defined to stop the component motions and accelerate the loaded FFSC for the next impact. With the angular velocities, nodal positions and velocities are used to establish angular velocities.

Because there is only significant angular motion upon rebound in one drop scenario (and it is about the long axis of the FFSC), stopping the FFSC angular velocity (which represents 80% of the loaded FFSC mass) is of primary concern. Consequently, loads are applied to the FFSC to gently stop its angular motion and its stopped orientation dictates the frame of reference of the next impact (i.e. which direction gravity is pointed).

The stopping of the motion and accelerating for the next impact happen over 0.01 seconds. Though the time to set up the next impact is short, possible interaction between the components during this time can make the next impact initial conditions approximate.

As evidence that each impact occurred with reasonable initial conditions, figures are provided for each drop scenario that show the loaded FFSC velocities for each impact and figures that show the loaded FFSC orientation near the point of impact. For the first impact, the loaded FFSC is simply passing through a gravity field as the swagging occurs. Consequently, the velocity amplitude in the y-direct should increase to the correct impact velocity before impact. The impact orientation should remain constant and not be questionable.

In a sequential impact(s), the plotted velocities are transformed to the frame of reference for the impact (i.e.

the frame of reference having a local x-z plane on the impacted surface and local y-direction perpendicular to the impacted surface). Due to the previous impact rebound motion, nonzero velocities are expected in all directions at the start of the load and accelerations application of a sequential impact. For reasonable initial conditions of a sequential impact, the x- and z-direction velocities should be at or near zero and the y-direction velocity should be at or near the desired impact velocity at 0.01 seconds. Also, the plotted orientation should be at or near the desired impact orientation.

For all the drop scenarios, once initial conditions have been established, the impact and rebound occur with only gravitational loading.

Energy curves are provided for all of the presented drop scenarios. The energy units are in*lbf and the time is in second. Artificial strain energy represents the energy required to keep reduced integration elements from taking on a zero energy hourglass shape. As a measure of model run acceptability, the artificial energy is normally compared to the total energy in the model. Where loads and accelerations are added for sequential drops, the total energy may not represent the most significant energy. Consequently, for this evaluation the artificial energy is compared to the total energy or the maximum plastic strain energy based on which is larger. Considering this comparison, the maximum artificial energy percentage for all the model runs is 3.1%. Therefore, the potential error associated with artificial energy is not considered to be significant.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B87 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-4.1 Results for the Benchmark Test The drop scenario considered in this section is a 4-foot drop [CN1-1 in the ATR FFSC SAR (2017)]

sequentially followed by a 30-foot drop [CD5-1 in the ATR FFSC SAR (2017)]. Both impacts are oriented so that the loaded ATR FFSC impacts with its center of gravity over the top corner. The stated purpose of the model run (given in the main body, Section 2.0, Table 2) is to show that the model is reliable. To accommodate this purpose, Section B-4.1.1 provides the results from the physical drops and Section B-4.1.2 provides the FEA benchmark test results for comparison.

B-4.1.1 Results from the Physical Drops Relative to the Benchmark Test A summary of the physical drop scenario results for the benchmark test are provided in the ATR FFSC SAR (2017), Sections 2.12.1.4.1.1 and 2.12.1.4.6, and 2.12.1.5.2. These sections discuss the CN1-1 and CD5-1 results and ATR fuel element inspection respectively.

Figure B-4.1.1-1 shows the ATR Package Orientation Markings defined in the ATR FFSC SAR (2017). This is provided for information Figure B-4.1.1 ATR Package Orientation Markings [ATR FFSC SAR (2017), Figure 2.12.1-4].

The discussion below and Figures B-4.1.1-2 and B-4.1.1-3 are from the ATR FFSC SAR (2017),

Section 2.12.1.4.1.1. This discussion summarizes the actual CN1-1 results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B88 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements The impact location was at corner number 5 identified in Figure 2.12.1-4. Following impact, the CTU bounced slightly and tipped over onto its side. There was minor visible exterior damage at the impact corner. The maximum deformation at the corner was approximately 1/8 inch. The closure handle was also deformed as a result of the drop. The overall length of the package did not change other than the 1/8 inch at the impact corner and compression of the closure handle of approximately 1/2 inch on one side. There was also a 1/8 inch deformation on the side corner approximately 1 1/4 inch from the impact corner. There was no visible deformation or rotation of the closure, other than the handle. Figure 2.12.1-6 and Figure 2.12.1-7 show the CTU following the NCT drop.

Figure B-4.1.1 CN1-1 Impact Damage [ATR FFSC SAR (2017), Figure 2.12.1-6].

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B89 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 CN1-1 Impact on Closure Handle [ATR FFSC SAR (2017), Figure 2.12.1-7].

Figure B-4.1.1-4 shows ATR FFSC SAR (2017), Figure 2.12.1-12. This is the fuel element damage following the CD1-1 drop scenario which was the drop immediately after CN1-1.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B90 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 Inspection of Fuel Element Following CD1-1 which was the drop immediately after CN1-1 [ATR FFSC SAR (2017), Figure 2.12.1-12].

The discussion below and Figures B-4.1.1-5 and B-4.1.1-8 are from the ATR FFSC SAR (2017), Section 2.12.1.4.6. This discussion summarizes the actual CD5-1 results.

Following impact, the CTU bounced slightly and tipped over onto its side. The impact corner was deformed in approximately 5/8 inch. There was modest deformation on the sides of the package near the impact location bulging in approximately 1/2 inch near the index lug pocket and bulged out approximately 5/8 inches on the adjoining side. The impacted corner deformed in approximately 5/8 inch and the opposite corner, #1, had no change in length. Figure 2.12.1-33 through Figure 2.12.1-36 show the CTU following CD5-1.

Following the drop, the closure assembly exhibited deformation with the end of the package and was unable to be rotated more than 1/8 inch in either direction. The locking pins showed no visible signs of deformation and the pin by #8 remained in the locked position. Both locking pins were functioning and able to be moved and compressed against the spring when tested by hand.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B91 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 CTU Following CD5-1 Impact [ATR FFSC SAR (2017), Figure 2.12.1-33].

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B92 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 CD5-1 Impact Damage on Bottom 180º Side [ATR FFSC SAR (2017), Figure 2.12.1-34].

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B93 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 CD5-1 Impact Damage on Closure End [ATR FFSC SAR (2017), Figure 2.12.1-35].

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B94 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 CD5-1 Impact Damage on Closure Area [ATR FFSC SAR (2017), Figure 2.12.1-36].

Figure B-4.1.1-9 shows ATR FFSC SAR (2017), Figure 2.12.1-58. The fuel element damage in Figure B-4.1.1-8 can be attributed to the CD5-1 drop scenario.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B95 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.1 Fuel element damage attributable to CD5-1 [ATR FFSC SAR (2017), Figure 2.12.1-58].

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B96 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements B-4.1.2 FEA Results for Benchmark Test The FEA model results for the benchmark test model are shown below in Figures B-4.1.2-1 to B-4.1.2-16.

This drop scenario is a 4-foot drop [CN1-1 in the ATR FFSC SAR (2017)] sequentially followed by a 30-foot drop [CD5-1 in the ATR FFSC SAR (2017)]. Both impacts are oriented with the loaded ATR FFSC impacting with its center of gravity over the top corner. The fuel element weights 22.1 lbf. The material properties are defined in Table B-2.1-2 for the FFSC body, Table B-2.1-4 for the FFSC lid, Table B-2.1-6 for the enclosure, and Table B-2.1-7 for the fuel element.

Total energy External work Kinetic energy Artificial strain energy Plastic strain energy Recoverable strain energy Frictional energy Damage dissipation energy Figure B-4.1.2 Benchmark test energy curves.

Figure B-4.1.2-1 shows the energy curves for the benchmark test. As is apparent by the kinetic energy, the first impact occurs near a run time of 0.02 seconds and the second impact occurs near a run time of 0.05 seconds. These curves exhibit a stable and acceptable shape.

This FEA model is run with a step for each impact. As evidence that both impacts occurred with reasonable initial conditions, Figure B-4.1.2-2 shows the loaded FFSC velocities for each step and Figures B-4.1.2-3 and B-4.1.2-4 show the loaded FFSC orientation near the point of impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B97 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 100 First Impact Velocity [in/sec]

0

- x-direction 100

- y-direction 200 0 0.01 0.02 0.03 200 Second Impact 0

Velocity [in/sec]

200 400 600 0 0.01 0.02 0.03 Time [sec]

Figure B-4.1.2 Loaded FFSC center-or-gravity velocities for the benchmark test.

Figure B-4.1.2-2 shows the loaded FFSC center-or-gravity velocities for the first and second impacts. For the first impact, the desired impact velocity is 192.5 in/sec (as shown in Section B-2.3.3). The FEA model velocity at impact is less than this value by less than 0.1%. Also, the horizontal velocities are near zero at impact. Therefore, the velocities at the first impact are acceptable.

For the second impact, the desired impact velocity is 527.2 in/sec (as shown in Section B-2.3.4). The FEA model velocity at impact is less than this value by about 1.4%. Though this is a little low, the accelerations are theoretically accurate. Also, being run as validation, it is desirable to use the defined approach without modification. The horizontal velocities are near zero (< 0.1 in/sec) at a time of 0.01 seconds (as is desirable per the discussion in Section B-4.0). Therefore, the velocities at the second impact are acceptable.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B98 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 First impact orientation for the Benchmark test.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B99 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Second impact orientation for the Benchmark test.

The impact orientations shown in Figures B-4.1.2-3 and B-4.1.2-4 are as desired for this sequential drop scenario.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B100 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Full model plastic equivalent strain after the first impact for the Benchmark test.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B101 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 FFSC plastic equivalent strain after the first impact for the Benchmark test.

As discussed in Section B-4.1.1, the most notable result for the physical drop was that the corner plastically deformed and produced a maximum deformation of about 1/8 inch. The FEA model produced a maximum deformation of 0.180 inches (and 0.109 inches one node in from the corner). Consequently, the FEA model produced reasonable/conservative deformation results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B102 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Lid plastic equivalent strain after the first impact for the Benchmark test.

As discussed in Section B-4.1.1, there was no visible deformation or rotation of the lid, other than the handle. The FEA model showed some plasticity in the pins and bayonets. However, it doesnt produce a ready visible deformation. Consequently, the FEA model produced reasonable deformation results. (The handle in the actual drop got pinched by the edge of the lid. In the FEA model, the handle is pushed over and down. This is not considered a significant discrepancy.)

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B103 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Fuel element plastic equivalent strain after the first impact for the Benchmark test.

Figure B-4.1.1-4 showed that the fuel element didnt suffer any significant damage in the first impact. The FEA model showed some plasticity and weld failure in the end box nearest the impact. The fuel element is modeled with minimum material properties other than the end boxes. Consequently, the FEA model produced reasonable/conservative deformation results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B104 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Enclosure plastic equivalent strain after the first impact for the Benchmark test.

The enclosure plastic equivalent strains are shown for information.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B105 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Full model plastic equivalent strain after the second impact for the Benchmark test.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B106 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 FFSC plastic equivalent strain after the second impact for the Benchmark test.

As discussed in Section B-4.1.1, the most notable result for the physical drop was that the corner plastically deformed and produced a maximum deformation of about 5/8 inch. The FEA model produced a maximum deformation of 0.833 inches (and 0.7333 inches one node in from the corner). Consequently, the FEA model produced reasonable/conservative change in length results. Additionally, Figure B-4.1.1-5 shows a bulge that is approximately 1/2 inch deep as measured. The FEA model approximates the shape of the bulge well. The FEA model change in the length between opposite walls at the bulge is approximately 0.415 inches. These measurements do not produce an exact comparison and the physical measurement can be expected to be larger. It is clear, however, that the FEA model bulge is reasonable in shape and magnitude. Consequently, the FEA model produced reasonable bulge deformation results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B107 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Lid plastic equivalent strain after the second impact for the Benchmark test.

As discussed in Section B-4.1.1, there was no visible deformation in the pins. The FEA model showed some plasticity in the pins. However, it doesnt produce a readily visible deformation. Consequently, the FEA model produced reasonable deformation results in the pins.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B108 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Lid contact pressure after the second impact for the Benchmark test.

As discussed in Section B-4.1.1, the lid wouldnt rotate more than an 1/8 inch in either direction. The FEA model showed substantial contact pressures in the lid which would indicate that it wouldnt be easily rotated.

Consequently, the FEA model produced reasonable results when compared to the observed results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B109 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Fuel element plastic equivalent strain after the second impact for the Benchmark test.

As is apparent in Figure B-4.1.1-4, the end box nearest the impact breaks off at the weld. The FEA model also shows this to occur.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B110 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Fuel without the failed end box displayed plastic equivalent strain after the second impact for the Benchmark test.

With the failed end box removed from the display of the fuel element, the FEA model results show a similar deformation pattern to that in Figure B-4.1.1-4. However, the fuel plates in the FEA model use minimum material properties and the modeled damage is more severe than the actual fuel element damage.

Consequently, the FEA model produced reasonable/conservative deformation results.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B111 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.1.2 Enclosure plastic equivalent strain after the second impact for the Benchmark test.

The enclosure plastic equivalent strains are shown for information.

B-4.2 Results for the CD3 Test The drop scenario considered in this section is a 30-foot side drop [CD3-1 in the ATR FFSC SAR (2017)]

sequentially followed by a 40-inch vertical drop with the lid impacting a puncture bar [CP1-1 in the ATR FFSC SAR (2017)]. The main body, Section 2.0, Table 2 provides the fuel element weight and stated purpose of the CD3 test. The fuel element weight is 44 lbf. The stated purpose of the model run is to demonstrate the integrity of fuel element swage. The FEA model results for the CD3 test model are shown below in Figures B-4.2-1 to B-4.2-10. The material properties are defined in Table B-2.1-2 for the FFSC body, Table B-2.1-4 for the FFSC lid, Table B-2.1-5 for the enclosure, and Table B-2.1-8 for the fuel element.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B112 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Total energy External work Kinetic energy Artificial strain energy Plastic strain energy Recoverable strain energy Frictional energy Damage dissipation energy Figure B-4.2 CD3 test energy curves.

Figure B-4.2-1 shows the energy curves for the CD3 test. As is apparent by the kinetic energy, the first impact occurs shortly before a run time of 0.02 seconds and the second impact occurs near a run time of 0.04 seconds. These curves exhibit a stable and acceptable shape.

This FEA model is run with a step for each impact. As evidence that both impacts occurred with reasonable initial conditions, Figure B-4.2-2 shows the loaded FFSC velocities for each step and Figures B-4.2-3 and B-4.2-4 show the loaded FFSC orientation near the point of impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B113 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 200 First Impact 0

Velocity [in/sec]

200

- x-direction 400

- y-direction 600 0 0.01 0.02 100 Second Impact Velocity [in/sec]

0 100 200 0 0.02 0.04 Time [sec]

Figure B-4.2 Loaded FFSC center-or-gravity velocities for the CD3 test.

Figure B-4.2-2 shows the loaded FFSC center-or-gravity velocities for the first and second impacts. For the first impact, the desired impact velocity is 527.2 in/sec (as shown in Section B-2.3.4). The FEA model velocity at impact is greater than this value by less than 0.1%. Also, the horizontal velocities are near zero at impact. Therefore, the velocities at the first impact are acceptable.

For the second impact, the desired impact velocity is 175.7 in/sec (as shown in Section B-2.3.5). The FEA model velocity at impact is greater than this value by about 0.4%. The horizontal velocities are near zero (<

1.0 in/sec) at a time of 0.01 seconds (as is desirable per the discussion in Section B-4.0). Therefore, the velocities at the second impact are acceptable.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B114 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 First impact orientation for the CD3 test.

Figure B-4.2 Second impact orientation for the CD3 test.

The second impact is offset on the post by 0.38 inches and is slightly rotated in a counterclockwise fashion as can be seen in the plot. The rebound of the first impact caused some angular motion of the internal components. The inexact impact orientation can be primarily blamed on interaction between the FFSC and

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B115 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements the internal components during the application of the loads and accelerations. However, the inexact orientation is not corrected because it still accommodates the stated purpose of the model run which is to demonstrate the integrity of fuel element swage. Consequently, the impact orientations shown in Figures B-4.2-3 and B-4.2-4 are reasonable for this sequential drop scenario.

Figure B-4.2 Full model plastic equivalent strain after the second impact for the CD3 test.

For this sequential drop scenario, there is nothing of particular interest in the time between the first and second impacts. Given that the fuel element damage is cumulative to the end of the model run, results are only presented at the end of the second impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B116 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 Fuel element plastic equivalent strain after the second impact for the CD3 test.

At the end of the second impact, there is significant damage in the end box nearest the second impact.

However, the fuel element is modeled with minimum material properties and end box damage is not of concern.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B117 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 Plastic equivalent strain in the vicinity of the swage after the second impact for the CD3 test.

This model shows some local damage in the ends of the fuel plates. However, the swaged connection between the fuel plates and side plates remains competent (i.e. the slippage is negligible and the fuel element retains its basic configuration). The stated purpose of this model run is that swage integrity is maintained. Therefore, the model results are acceptable.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B118 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 FFSC body plastic equivalent strain after the second impact for the CD3 test.

The FFSC body plastic equivalent strains are shown for information.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B119 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 Lid plastic equivalent strain after the second impact for the CD3 test.

The lid plastic equivalent strains are shown for information.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B120 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.2 Enclosure plastic equivalent strain after the second impact for the CD3 test.

The enclosure plastic equivalent strains are shown for information.

B-4.3 Results for the CD4 Test The drop scenario considered in this section is a 30-foot bottom drop [CD4-1 in the ATR FFSC SAR (2017)]

sequentially followed by a 40-inch vertical drop with the lid impacting a puncture bar [CP1-1 in the ATR FFSC SAR (2017)]. The main body, Section 2.0, Table 2 provides the fuel element weight and stated purpose of the CD4 test. The fuel element weight is 44 lbf. The stated purpose of the model run is to demonstrate the integrity of fuel element swage. The FEA model results for the CD4 test model are shown below in Figures B-4.3-1 to B-4.3-10. The material properties are defined in Table B-2.1-2 for the FFSC body, Table B-2.1-4 for the FFSC lid, Table B-2.1-5 for the enclosure, and Table B-2.1-8 for the fuel element.

Initial runs of this scenario showed some stability problems that started near the start of the second step. It was determined that there was difficulty for Abaqus (2021) reestablishing contact with the fuel plates and end box fragments (caused by the first impact). This region is distant from the second impact and contact in the problem area is not needed for the second impact. Consequently, contact with the end boxes and last

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B121 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements few inches of the fuel plate region (except swaging contact which is unchanged) is removed for the second step.

Total energy External work Kinetic energy Artificial strain energy Plastic strain energy Recoverable strain energy Frictional energy Damage dissipation energy Figure B-4.3 CD4 test energy curves.

Figure B-4.3-1 shows the energy curves for the CD4 test. As is apparent by the kinetic energy, the first impact occurs near a run time of 0.02 seconds and the second impact occurs after a run time of 0.04 seconds. These curves exhibit a stable and acceptable shape.

This FEA model is run with a step for each impact. As evidence that both impacts occurred with reasonable initial conditions, Figure B-4.3-2 shows the loaded FFSC velocities for each step and Figures B-4.3-3 and B-4.3-4 show the loaded FFSC orientation near the point of impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B122 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements 200 First Impact 0

Velocity [in/sec]

200

- x-direction 400

- y-direction 600 0 0.01 0.02 0.03 50 Second Impact 0

Velocity [in/sec]

50 100 150 200 0 0.02 0.04 0.06 0.08 0.1 Time [sec]

Figure B-4.3 Loaded FFSC center-or-gravity velocities for the CD4 test.

Figure B-4.3-2 shows the loaded FFSC center-or-gravity velocities for the first and second impacts. For the first impact, the desired impact velocity is 527.2 in/sec (as shown in Section B-2.3.4). The FEA model velocity at impact is less than this value by less than 0.1%. Also, the horizontal velocities are near zero at impact. Therefore, the velocities at the first impact are acceptable.

For the second impact, the desired impact velocity is 175.7 in/sec (as shown in Section B-2.3.5). The FEA model velocity at impact is less than this value by about 0.6%. The horizontal velocities are near zero (< 0.2 in/sec) at a time of 0.01 seconds (as is desirable per the discussion in Section B-4.0). Therefore, the velocities at the second impact are acceptable.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B123 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 First impact orientation for the CD4 test.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B124 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 Second impact orientation for the CD4 test.

The impact orientations shown in Figures B-4.3-3 and B-4.3-4 are as desired for this sequential drop scenario.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B125 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 Full model plastic equivalent strain after the second impact for the CD4 test.

For this sequential drop scenario, there is nothing of particular interest in the time between the first and second impacts. Given that the fuel element damage is cumulative to the end of the model run, results are only presented at the end of the second impact.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B126 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 Fuel element plastic equivalent strain after the second impact for the CD4 test.

At the end of the first impact, there is significant damage in the end box nearest the first impact. At the end of the second impact, the end box nearest the second impact is essentially failed away. However, the fuel element is modeled with minimum material properties and end box damage is not of concern.

(Note: As discussed at the start of the section, some contact was removed for model stability. This resulted in end box fragments scattering where they shouldnt be able to go. Once failed, they conservatively do not contribute further to the model. Consequently, for clarity, these fragments are removed from the plot.)

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B127 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 Plastic equivalent strain in the vicinity of the swage after the second impact for the CD4 test.

This model shows some local damage in the ends of the fuel plates. However, the swaged connection between the fuel plates and side plates remains competent. The stated purpose of this model run is that swage integrity is maintained. Therefore, the model results are acceptable.

The comb is not shown because it began to pass through the fuel plates after contact was removed for the second impact (as discussed at the start of the section). The combs are not important to the stated purpose of this model run.

TEM-10200-1, Rev. 12 ECAR-5644, Rev. 2 ENGINEERING CALCULATIONS AND ANALYSIS 04/12/2021 Page B128 of B189 Selected Sequential Drop Analyses for the ATR FFSC with Heavier LEU Fuel Elements Figure B-4.3 FFSC body plastic equivalent strain after the second impact for the CD4 test.

The FFSC body plastic equivalent strains are shown for information.