ML17132A246

Redacted Attachment 8: General Atomics 30441R00017, Rev. C, Reactor-Based Molybdenum-99 Supply System Project, Ansys Target Cartridge, Housing Structural Analysis Design Calculation Report.

ML17132A246
Person / Time
Site:	University of Missouri-Columbia
Issue date:	02/07/2017
From:	General Atomics
To:	Office of Nuclear Reactor Regulation
Shared Package
ML17132A252	List: ML17132A240 ML17132A241 ML17132A243 ML17132A244 ML17132A245 ML17132A246
References
30441R00017, Rev. C
Download: ML17132A246 (73)

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Attachment 8 RELEASED 30441R00017 COM A vd 2017/02/07 Revision C REACTOR-BASED MOLYBDENUM-99 SUPPLY SYSTEM PROJECT ANSYS TARGET CARTRIDGE, HOUSING STRUCTURAL ANALYSIS DESIGN CALCULATION REPORT Prepared by General Atomics for the U.S. Department of Energy/National Nuclear Security Administration and Nordion Canada Inc.

Cooperative Agreement DE-NA0002773 GA Project 30441 WBS 1100

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Attac hment 8 ANSYS Target Cartridge, Housing Structural Anal ysis Design Calculation Report 30441 R00017IC REVISIO N HISTORY Revision Date Description of Changes A 240CT16 Information Issued Initial Release B 27JAN17 Revised to update the change in cartridge design c 07FEB17 Incorporated MUR R Comments and Updated Table 17 POINT OF CONTACT INFORMATION PREP ARED BY:

Name Position Email Phone Juan Armando Chavez Engineer Juan .Chavez@ga .com 858-455-2465 APPR OVED BY:

Name Position Email Phone Oscar Gutierrez Task Lead Oscar.Gutierrez@ga.com 858-455-3655 Bob Schleicher Chief Engineer Bob.Schleicher@ga.com 858-455-4 733 Kathy Murray Project Manager Katherine .Murray@ga.com 858-455-3272 Katherine Partain QA Manager Katherine. Partain@ga.com 858-455-3225 DESIGN CONTROL SYSTEM DESCRIPTION D R&D DISC QA LEVEL SYS D DV&S

[81 DESIGN D T&E N II N/A D NA ii

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017/C TABLE OF CONTENTS REVISION HISTORY ...................... ................. ........................................ .. .. ....... .......................... ii POINT OF CONT ACT INFORMATION ..... .... .......... ..................................................................... ii DESIGN CONTROL SYSTEM DESCRIPTION ............... ............................................................. ii ACRONYMS ................................................................................................................................ vi 1 INTRODUCTION ...................................................................................... .. ....................... 1 2 APPLICABLE DOCUMENTS ........................................................................................... 1 3 DESIGN OF STRUCTURES, SYSTEMS AND COMPONENTS ...................................... 2 3.1 SGE Experimental Facility Description ... ............ .. ..................................................... 2 3.2 Target Assembly Description .. ................. .................... .. ............. .......... .. ...... .... ........ 4 3.2 .1 Mechanical Design .... .. .................. .... ............................................ .................... 4 3.2.2 Target Housing .... .... ....... ..... ... .. .... .. ....... ...... .. .......................... .. .............. .. ........ 6 3.2.3 Target Cartridge Assembly ............................................................... ................. 7 3.2.4 Cooling Flow Path ........................................ .. ................................................. 13 3.2.5 Materials of Construction .. ... .. .. .... ... ..................... .. ..... ............. ... .... .. .. ....... .. .... 16 4 CODES AND STANDARDS ........................................................................................... 17 4.1 Design , Fabrication and Operation ..... ... .................................................................. 17 4.2 Software .. ..... ..... ....... .......... ... ................... .... .. ..... .. .. ....... .. .. ..... ........ ... ... ........ ... ....... 18 5 DESIGN INPUTS ............................................................................................................ 18 5.1 Mechanical Design ......... .... ................. .............. ................ .... ............. .. .. ...... .... .... ... 19 5.1 .1 Target Housing ....... ........ ........ ..... ....... .... .... ........ ...... .... ............... .... .. .... .... .... .. 20 5.1.2 Cartridge Assembly ..... ............ ... .. .... ... ...... .. ........... .. ...... ...... ........................... 21 5.2 Thermo- Hydraulics Summary ...... .. ....................................................... ..... ... .... .... .. 22 6 ASSUMPTIONS ... .......... .............................. ................................................................... 22 7 STRUCTURAL ANALYSIS OF TARGET SYSTEM .................... ................................... 23 7 .1 Material Allowables ................................................................................................. 23 7.2 Results ..... ....... .............. ................... ...... ......... .. ................................... .. .. .. ...... ....... 26 7.2.1 Target Housing ..... ...... ...... ....... .. ..... .... ....... .. ....... .... .... .. ...... ..... ..... .... ........ ....... 26 7.2.2 Cartridge Assembly ..... .. ............................ ...... ... ......................... .................... 33 7.2 .3 Handling Tools ........... .... ............... ..... ..... ..... ..... ... ........ ..... ... .................... ........ 52 8 RESULTS

SUMMARY

.................................................................................................... 53 9 REFERENCES .......................... ...................................................................................... 55 APPENDIX A-CHRIS DOHM EMAIL AND SELECTED REPRESENTATIVE IMAGES ........ A-1 APPENDIX B - TARGET ROD BOWING DUE TO THERMAL AND IRRADIATION EFFECTS FOR SGE EXPERIMENTAL FACILITY ........................................................................ B-1 iii

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC LIST OF FIGURES Figure 1. SGE process scope, functional relationships and interfaces ........ ......... ... .................... 3 Figure 2. Layout of SGE experimental facility in the MURR reflector region and containment.. .. 4 Figure 3. MURR map for fuel elements and reflector regions ..... ...................................... ...... ..... 5 Figure 4. Target assembly (front and back views) ........................................................... ............ 6 Figure 5. Illustration of target housing assembly elevation and plan views ................................. 7 Figure 6. Target cartridge assembly and target assembly section view ............................... ....... 8 Figure 7. Target assembly upper and lower sections ............................................... .... ...... .. ....... 9 Figure 8. Target rod lower end cap pins position rods relative to lower housing water plenum . 10 5a, b, Figure 9. . .... .................................... .... ... ................................... 11 d, e, f Figure 10. Target rod arrangement ............................................................................... ............. 12 Figure 11. Inlet and outlet plenum extensions with method of attachment. Water flow is in blue ................................................................................................................................. 13 Figure 12. Lower target head ........... ........ ........... ................................ ......... ...... ....... .. ......... ...... 14 Figure 13. Upper target head arrangement. Water flow is in blue ............................................. 15 Figure 14. Locking and unlocking mechanism ............................................................................ 16 Figure 15. Total pressure minus outlet static pressure cooling water through target assembly from point 1 to 6 at 100%, 115% flow vs max design conditions. Taken from 30441 R00038 ......... ................ ...................................... ............................... .................... 20 Figure 16: Allowable strength temperature Al 6061T6 and SST316L from ASME B&PV .. ........ 24 Figure 17. 21.5 psi design conditions model for the housing assembly, stresses and deflections ......... .......... ..... ............. ........... ............ ....... ..... .................. .. ..... .... ...... .... ........ 27 Figure 18. Linearized stress near corner for 21 .5 psi [148.24 kPa] pressure design condition structural model for the housing assembly .... ... ............................................... ............. .. . 28 Figure 19. SST316L fatigue curve from ASME code (Reference 11) .... ............... ..................... 29 Figure 20. Aluminum 6061-T6 fatigue curve taken from "Fatigue Design Curves for 6061-T6 Aluminum" (Reference 12) ................................... ................ ................. .................... ...... 29 Figure 21. Geometry of the lower housing flange with a 13 bolt configuration .......................... 30 Figure 22. Deflections of the c-seal flange and groove under pressure and moment loads ...... 32 Figure 23. Radially outward load. 88.181bs/40kg equivalent at top of pool ... ................ ...... ...... 33 Figure 24. Cartridge at 14.80 psi design pressure condition. Stresses and deflections ........... 34 Figure 25. Cartridge at 14.80 psi design pressure condition . Linearized stress through cartridge wall ....... .... ................... .. ....... ........ ....... .... .. ......... ... ... ...... .......... ... ................... .... ....... ...... 35 Figure 26. Linearized stresses of cartridge through at weld location for 14.80 psi loading conditions ................................. ...... ...... ............................................. .... ..... .................... . 36 Figure 27. Cartridge at 14.80 psi design pressure condition. Pin maximum linearized stresses ............. .... ... ............................... ........................................................................ 37 Figure 28 . Cartridge at 12.16 psi design pressure condition (115% max flow). Pin maximum linearized stresses ................... ..... .. ............. ....... ... ......................................................... 38 Figure 29. Pellet and cladding details ........ .... ....................................... ..................................... 46 Figure 30 . Allowable stress for Zircaloy-4 (irradiated) based on 2/3rd yield [ ASTM STP 1245 (Reference 15)] ..... .... ............ ..... .................................. ... .... .......... .... .............................. 47 Figure 31 . Fatigue chart Zircaloy-4, 350°C (un-irradiated and irradiated) (Reference 16 & 17) 48 iv

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C Figure 32. Diffuser weight analysis, meshing .. .. ......................... ......... .. .................................... 51 Figure 33. Diffuser weight analysis , stress results for 80N load .. .......... ... ......... .... ..... ..... .... ....... 51 Figure 34. Diffuser weight analysis, stress results for 727N load ....... ........... .. ....................... ... 52 Figure 35. Cartridge assembly lifting and locking features .................................... ... ... .............. 53 Figure 36. 3D geometry for target rod bowing analysis . ..... .... ...... ............ .......................... ..... B-1 Figure 37. Ratio of power density between front and back of U02 pellets throughout GA RB-MSS ...... ................................................. .. ............... ..................... .......... .. ..................... B-2 Figure 38. Radial temperature profile of target rod for worst case power skew ....................... B-4 Figure 39. Therma l deformation in axial direction of RB-MSS target rod end cap ..... ........ .... .. B-5 Figure 40. Deflection due to rod bowing for worst-case front-to-back power skew .................. B-7 LIST OF TABLES Table 1: Target Rod Dimensions (Cold) ..................................... ........ ..... ... ............................. ... 12 Table 2: Target Assembly Loading ............................................. ..... ... ........ .. ...... .. .................. .... 20 Table 3: Materials of Construction ....... ..... ...... ...... .. ..... ..... ............................................. ... .......... 23 Table 4: Zircaloy - 4 Zirconium Alloy, UNS R60804 from MatWeb.com Vs FRAPCON .... .... ..... 25 Table 5: Geometric Dimensions Used in FRAPCON Analysis ............................. .. ........ ..... ...... .40 Table 6: Power Histories Used in FRAPCON Analyses .... ............................................ ....... .... .. 41 Table 7: Axial Power Profile Used in FRAPCON ...... ... ...... ........ ................................ ....... .. .. .... ..42 Table 8: Cladding Outer Diameter Temperature for Target Rod 17 ........................................... 43 Table 9: Additional FRAPCON Input Parameters .................. ... .................... .............................. 43 Table 10: FRAPCON Results at 0.05 days at 115% Power ................. .. .................. .................. 44 Table 11: FRAPCON Results at 1.05 days at 100% Power ..................... .... ..... ..... .......... ......... .44 Table 12: FRAPCON Results at 19.28 days at 100% Power ..... .. .... .. ..... ....................... ..... ...... .44 Table 13: FRAPCON Results at 20.33 days at 115% Power .............. .. ..... .... .. .................. .. ..... .45 Table 14: FRAPCON Results Summary .... .................................................... ....... .................. .... 47 Table 15: Flow Induced Vibration Results ..... ... ......... ................ ........... ... ................. ......... ... ... ... 49 Table 16: Weight of Cartridge Components ... .... ..... .................................... ....................... ....... .. 50 Table 17: Cartridge and Housing Design Limits .... .... ................................................................. 54 Table 18: Convection Conditions for External Tube .... ..... ................... ... .. .... ............... ......... .... B-3 Table 19: Power Density Variation in Pellet Stack for Average and Worst Case .............. ..... .. B-3 Table 20: Power Density Variation in Pellet Stack for Average and Worst Case ................ ..... B-6 v

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOD 17JC ACRONYMS Acronym Description ASME American Society of Mechanical Enqineers FEA Finite Element Analysis FEM Finite Element Model GA General Atomics GP a Gii:ia-Pascal kPa Kilo-Pascal LEU Low Enriched Uranium LWR Liqht Water Reactors MFC Mass Flow Controller Mo-99 Molybdenum-99 MPa Meqa-Pascal MSS Molybdenum Supply System MURR University of Missouri Research Reactor PSI Pounds per square inch RTD Resistance Thermometer Detector SGE Selective Gas Extraction TA Tarqet Assembly TS Tari:iet System vi

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17JC 1 INTRODUCTION The purpose of this document is to present calculation results showing that the Target Assembly (TA) components for the Once-Through Approach as part of the Reactor-Based Molybdenum-99 Supply System (RB-MSS) meet the applicable design requirements of the ASME Boiler and Pressure Vessel (B&PV) Code, Section VIII , Division 1 and 2, 2015 (References 1 and 2) and Section 11-B and D, 2015 (Reference 3)

Top level design requirements for the TA are defined in the "Molybdenum-99 Supply System Requirements Document" Doc No 30441 S00001 .

The Once-Through Approach design will be developed and demonstrated under the RB-MSS project, co-funded by the Department of Energy, National Nuclear Security Administration (DOE-NNSA) and Nordion (Canada), Inc. It is intended that the MSS will be installed and operated at the University of Missouri Research Reactor (MURR) to begin production of commercially-significant quantities of Mo-99 (~3000 6-day Ci/week) by the beginning of 2018. In addition to a summary-level description of the MSS conceptual design, this document describes the analysis performed to evaluate the performance of the Target Housing, Cartridge , Cladding and Diffuser components that make up the MSS Target Assembly.

2 APPLICABLE DOCUMENTS A list of applicable documents is provided below.

Document Number Document Title 30441 M00029 Maximum Neutron Damage of Zirc-4, Al 6061 -T6 and SS 316 30441 R00002 MCNP 6 Version 1.0 Verification Test Report 30441 R00020 ANSYS Workbench (Version 16.0) Software Verification Test Report 30441 R00021 Target Assembly Thermal Analysis 30441R00028 FLUENT (Version 16.0) Verification Test Report 30441 R00031 Mo-99 Target Assembly Nuclear Design for Once-Through Operation RELAP Accident Analysis and FRAPTRAN Target Rod Transient Analysis 30441R00032 Design Calculation Report Analysis of Forced Convection Cooling of Target Rods with 2 Phase 30441R00033 Considerations Computational Fluid Dynamics Analysis Of Target Housing Design 30441R00038 Calculation Report 30441S00001 Molybdenum-99 Supply System Requirements Document 30441S00008 Mo-99 Supply System List of Principal Design Parameters Quality Assurance Program Document - Phase 11 , Reactor-Based QAPD-30441-11 Molybdenum 99 Supply System (RB-MSS) 1

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017/C 3 DESIGN OF STRUCTURES, SYSTEMS AND COMPONENTS 3.1 SGE Experimental Facility Description The SGE experimental facility employs a first-of-a-kind concept for radioisotope production . It is a reactor-driven , LEU based system that selectively removes specific isotopes of interest, viz. ,

Mo-99, in gaseous form , that are produced from fission during irradiation of Zircaloy-4 clad target rods containing LEU in the form of U02 pellets that are nominally enriched to 19.75% U-235. The target rods will be contained in Al6061 cartridges that ensure uniform cooling water flow around the target rods and will be located in the graphite reflector region of the 10 MW University of Missouri Research Reactor (MURR). The SGE facility will be operated by MURR staff in concert with MURR's routine reactor operations.

During SGE system operation , one or two target cartridges hold ing up to 11 target rods each are placed in permanently installed support assemblies in the graphite reflector location. Fission product isotopes including Mo-99 are generated during target irradiation. At the end of irradiation ~a , d,

( ), the target rods, following a short period of cooling (to reduce decay heat and f e,

certain short lived isotopes), are removed and transferred to a bank of hot cells using an intra-facility, shielded transfer cask, also designed for adequate heat dissipation during transfer. Here, the irradiated target rods are decladded to remove the irradiated U02 pellets, which are then subject to the selective gaseous extraction process (SGE) to separate the Mo-99 in gaseous form to a collection apparatus . The product is then further processed to separate molybdenum from the collection process by-products and impurities. The product is then packaged and shipped to a licensed radioisotope facility for final purification that meets the required U.S. Food & Drug Administration (FDA) purity standards for fabrication of Tc-99 generators. The residual uranium-containing powder is reduced to U02, encapsulated and placed in sealed storage containers for eventual disposal.

The fully-loaded target cartridges themselves are each , and together, subcritical in water (kett < 0.8) as detailed in 30441 R00031 . Fission only occurs in the target when exposed to neutron irradiation from the reactor.

Figure 1 shows a functional block diagram of the SGE process including process streams, subsystem and interfaces with the reactor and containment facility.

2

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 IC Collection System (Ory Chemistry!

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"'""Purlfic..tion System Cladding Waste C2.C Solid WHt* Cementatlon Figure 1. SGE process scope, functional relationships and interfaces The SGE facility is divided into separate subsystems. The Target System includes a Target Assembly and a Target Loading and Unloading station. The Target Housing is described in Section 3.2.2. The Cartridge Assembly is described in Section 3.2 .3. Figure 2 shows a layout of the SGE systems within the MURR reactor pool and containment building. The cartridge loading station is where the target rods are removed from the cartridge and placed in a transfer cask. The cartridge is reloaded with fresh or dummy target rods in this location.

3

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017IC CARTRIDGE LOADING/Ul'iLOADING STATIO N CARTRIDGE WITH TARGET RODS 5a, b, TARGET d, e, f ASSEMBLY IN GRAPHITE REFLECTOR POSIDON Figure 2. Layout of SGE experimental facility in the MURR reflector region and containment 3.2 Target Assembly Description 3.2.1 Mechanical Design The target assembly (TA) is designed to be installed in each of the reactor graphite reflector positions 5A and 5B as shown in Figure 3. The housing is held laterally in place by an indicator hole in the reactor baseplate and vertically in place by the target cooling system inlet pipe which includes a compressible link. Each target assembly consists of a water inlet section, a target housing, a lower plenum, a cartridge assembly, an outlet diffuser, and a cartridge locking mechanism. Figure 4 shows the target assembly components. The modeling and mechanical design of the target assembly components in 30 was performed using the commercially available SolidWorks 2016 software package.

4

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17 IC Wedge SA Wedge SB Figure 3. MURR map for fuel elements and reflector regions 5

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C Water inlet (Al6061)

RTDs Cartridge locking mechanism (x2)

(Al6061)

E Cartridge (0 c:: 5a, b, C") (Al6061)

(0 C")

d, e, f Target housing (Al6061)

~Target housing lower plenum (SST316L)

Figure 4. Target assembly (front and back views) 3.2.2 Target Housing The functions of the target housing are to direct the flow of cooling water, provide structural support, and position the cartridge within the reactor reflector. Figure 5 shows vertical and plan cutaway of the target housing. The target housing is fabricated from welded Al6061 plates while the lower housing plenum is fabricated from SS316L. Cooling water is fed to the target housing by the target cooling system through a line at the top of the assembly. The target housing then directs the water down through the lower plenum , up the inside of the cartridge and finally exiting out the diffuser into the MURR pool. The target housing and the lower housing plenum are bolted together and water leakage is prevented by a metal c-seal that keeps this interface water tight.

6

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC water water Inlet (Al6061)

Engaging lug for locking cartridge locklng target housing mechanism (Al6061)

(Al6061) cartridge guide rails (Al6061) cartridge mounting plate (SST316L)

C-seal lower hou1lng plenum (SST316L) cartridge locking pins (SST316L)

Indicator Stub (SST316L)

Figure 5. Illustration of target housing assembly elevation and plan views The bottom of the housing has a locator stub that fits in the reactor support structure , which bears the weight of the assembly and attached piping . The load from the piping is transferred to the lower housing plenum by the target and the housing sides. The lower housing water plenum is bolted to the target housing with a c-seal to prevent loss of cooling water before reaching the cartridge and the target rods.

3.2.3 Target Cartridge Assembly 3.2.3.1 Cartridge The primary functions of the cartridge are to (a) position and support the target rods containing the LEU pellets, (b) provide a cooling passage for the target rods, (c)

, and (d) to mix and guide the water outlet 5a, b I flow. The cartridge assembly consists of an Al6061 diffuser on the top, an Al6061 cartridge flow d e, f I

housing, an Al6061 lower cartridge flange , a locking mechanism, and 11 single Zircaloy-4 clad target rods.

The target rods are vertically oriented in a single plane positioned in the target cartridge orthogonal to the direction of the neutron flux (Figure 6). The planar orientation and location ensures the SGE facility maximizes the Moly-99 production while remaining sub-critical. The target rods are held in position by the top and bottom cartridge flanges which contain holes for the coolant to flow around the target rods. The cartridge is secured in place by a locking 7

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C mechanism located on top of the diffuser. The locking mechanism engages and disengages to the top of the target housing.

9.5 in Cartridge locking Diffuser mechanism (Al6061) Target housing (x2) waler channel target hou1ing (Al6061) CD 5'

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Cartridge ftow hou1lng (Al6061) lower cartridge Neutron

~ ftange (Al6061) flux Figure 6. Target cartridge assembly and target assembly section view Figure 7 shows the cartridge upper and lower sections highlighting key components and features of the design. The cartridge is a clamshell design that will have two seam welds running the length of the cartridge. This simplifies the fabrication as well as allowing more control over the tolerances for the fit between the water cooling channels and the target rods. The cartridge is first located to the target housing by a pair of guide rails that lead to a pair of locating pins (Figure rs;,b.l 5). These highly tolerance pin~ are part of the target housing lower plenum and LJ receive and place the cartridge in its final position in relation to the reactor core. The cartridge is then held in place by a locking and unlocking mechanism that releases the cartridge from the target housing, consisting of couple of levers actuated by two spring loaded bolts that hold the pressure and water flow loads of the target assembly and is explained in more detail in Section 3.2.4.4.

8

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17IC

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Figure 7. Target assembly upper and lower sections The target rods are fixed ori the top (upper endcap) and laterally restrained at the bottom (lower endcap) allowing room for axial thermal expansion I:a, b, I The target rods are expected to thermally grow by< 2 mm, leaving - for margin including mechanical tolerance stack-ups. The target rods are located and held concentric to the water channels by 11 cup features that are fabricated into the lower cartridge flange and can be seen on Figure 8. Target rod lower end cap pins position rods relative to the lower housing water plenum. This ensures even flow velocities around the target rods through the cartridge. The water cutouts on the cup features are smaller than the pointed end cap of the target rod. This eliminates the possibility of the target rod getting stuck on one of these water bypass features when inserting them into the cartridge and ensures the worker can always find the center of the cartridge and guide the target rod into its final position.

9

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17IC 5a, b, d, e, f Figure 8. Target rod lower end cap pins position rods relative to lower housing water plenum The water cutouts are designed to create near-uniform coolant flow over the target rods as soon as the water enters the cartridge.

5a, b, d, e, f 10

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 IC 5a, b, d, e, f 3.2.3.2 Target rods The function of the target rod is to contain the U02target pellets and to prevent fission gas release .

Figure 1O shows an individual target rod assembly. The target rod consists of an upper end cap, cladding, a spring, one hundred U02 target pellets , and a lower end cap. - [5;d"l The U02 target pellets have a nominal active length of 23.6 inches

~

(600 mm) in the cold state. A nominal radial gap of 50µm exists between the pellet OD and the cladding ID. This nominal gap offers the best dimensional balance between cladding strain and thermal conductivity to the cladding wall. The end caps are fabricated from Zircaloy-4 bar with integrated features designed to optimize installation and extraction from the cartridge. Both end caps are welded to the cladding autogenously (no filler rod) by a standard automated orbital weld head. The stainless steel spring is held captive by the upper end cap, to aid in easier recovery post-irradiation . Table 1 lists the individual pelleUclad components and dimensions.

The Zircaloy-4 (UNS R60804) cladding will be fabricated and inspected in accordance with seamless alloy tubes for nuclear reactor fuel cladding applications per American Society for Testing and Materials (ASTM) 8811 . The Zircaloy-4 (UNS R60804) end caps and stainless steel spring will be fabricated from bar material in accordance to ASTM 8351.

11

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 3044 1R00017/C

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Figure 10. Target rod arrangement Table 1: Target Rod Dimensions (Cold)

Component Nominal value inches (mm)

Active target rod length (cold ) 23 .6 (600)

Total target rod length 26.505 (673)

Pellet height 0.236 (6)

Pellet outside diameter 0.197 (5)

Clad ID 0.201 (5.1)

Clad OD 0.240 (6 .1) 12

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017 JC 3.2.3.3 Diffuser The functions for the diffuser are a) to capture the target rods (Figure 7), b) provide water mixing for an outlet water temperature measurement, c) divert the flow away from MURR equipment, and d) to guide 16 N flow away from the pool surface. The water is mixed in the diffuser's water flow mixing region (Figure 11) to allow for a bulk water temperature measurement. The exit temperature measurement is used to determine the Target System power.

3.2.4 Cooling Flow Path 3.2.4.1 Target Water Flow Path Figure 11 shows the path of cooling water flow in the target system. Cooling water enters the housing from the inlet pipe and flows into the open lower plenum turning into the lower cartridge flange. The lower cartridge flange has labyrinthine features to minimize water bypassing the target rods during normal operations. The flow then travels around the target rods, into the diffuser and is ultimately ejected to the reactor pool.

5a, b, d, e, f Figure 11 . Inlet and outlet plenum extensions with method of attachment. Water flow is in blue 3.2.4.2 Lower Target Housing and Cartridge Figure 12 shows a cross-section of the target housing lower water plenum. The bottom of the housing has a locator stub that fits in the reactor support floor, which bears the weight of the 13

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC assembly and attached piping . The load is transferred to the target bottom through the housing sides . The target rods are supported from upper cartridge flange and simply supported from the bottom endcaps by the lower cartridge flange, which also provide the target rods with concentricity to the cartridge water channel (with margin for thermal growth). The lower hous,ing water plenum is bolted to the target housing . This interface is then sealed with a c-seal to prevent loss of cooling water before reaching the cartridge and the target rods.

Figure 12. Lower target head 3.2.4.3 Upper Target Housing and Cartridge Figure 13 shows the upper target housing, cartridge, and lower section of the diffuser. The lower flange of the diffuser acts as the lid that holds down the target rods and keeps them from coming out of the cartridge by capturing the target rod 's upper end cap. This , along with the lower cartridge flange supporting the target rods , properly constrains the target rods through the installation, irradiation , and transfer to the temporary holding area inside the pool. The lower diffuser flange is welded to the neck portion of the diffuser, which collects the water exiting the cartridge and mixes it together before guiding it to the resistance temperature detector (RTD) for measurement and ultimately to the pool. The mixing of the flow is very important to be able to take an accurate measurement of the power being generated by the target assembly, particularly when not all of the target rod positions are filled with LEU rods . Mo-99 production may require anywhere between 3 to 11 target rods to be irradiated at a time , with the rest being dummy rods .

The water flowing over the dummy rods will exit into the diffuser much cooler than the water from the actual target rods, thus mixing of the flow is critical for an accurate power measurement. At 14

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017IC each interface, cartridge flange to lower diffuser flange to diffuser ducting , the water cross-sectional area remains constant.

Figure 13. Upper target head arrangement. Water flow is in blue This allows the diffuser to have a minimal pressure drop from the cartridge exit to the reactor pool.

When it is time to remove the irradiated cartridge from its irradiation position in the reflector for transfer to the in-pool loading/unloading station , the cartridge will be maneuvered and handled remotely in the reactor pool by the operator positioned on top of the pool. The cartridge is moved from the reflector wedge to the in-pool unloading station , where the diffuser is un latched from the cartridge to access the target rods for loading into the transfer cask. The diffuser is attached to the cartridge by using two positive lock, spring loaded , quarter turn , cam lock bolts that engage to the cartridge upper flange. The two bolts are readily accessible and visible from the top by the operator and tools have been developed to perform such a function within the reactor pool.

15

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C 3.2.4.4 Cartridge Locking Mechanism The locking and unlocking mechanism that releases the cartridge from the target housing consists of couple of levers actuated by two spring loaded bolts that hold the pressure and water flow loads of the target assembly. As seen in Figure 14, the holding levers are controlled by the two bolts that slide laterally when the bolts are rotated which in turn makes the lever pivot to clear the locking lug attached to the target housing . This releases the cartridge to be lifted to the unloading/loading zone higher up in the pool. These two 1/4-20 bolts are more than enough to restrain the cartridge from the anticipated vertical load from the flow of 15-20N and thus making this a secured experiment.

Cartri~ Assembly Locking lug Ca:rtrildge Assembly, Diffuser Locling Mechanism Actuation l eYl!r 2x c.rtridge Assembly, Locking M echanism l ockin&/unlocking bolt 4K Cartridge Asse bly, Diffuser Locking Mechanism Spring Flexures Figure 14. Locking and unlocking mechanism 3.2.5 Materials of Construction 3.2.5.1 Design Basis for Target Assembly Materials The considerations upon which target assembly material selections are based are as follows :

(i ) Prior operating experience for target cladding materials in a nuclear reactor irradiation environment is preferable .

(ii) The materials must have good mechanical strength at temperature up to 400°C.

16

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17JC (iii) Materials in the neutron flux must have low neutron absorption cross-sections so as not to impede the rate of Mo-99 production.

(iv) Selected alloys must have the properties to support readily fabrication into required shapes and must be readily weldable.

(v) The material used for the inner clad of the target rod must not undergo undesirable chemical reactions with the target pellet material or fission products within the operating temperature range .

3.2.5.2 NRC-Approved Fuel Cladding Alloys Alloys that have been approved by the Nuclear Regulatory Commission (NRC) for fuel cladding in power and research reactors in the United States include Zircaloy , SS304, SS316L, and Al6061. Zircaloy-4 is the preferred candidate due to its lower neutron absorption, which results in higher product yield , and is also used in LWRs . The Zircaloy-4 (UNS R60804) cladding will be fabricated and inspected in accordance to seamless alloy tubes for nuclear reactor fuel cladding applications per ASTM 8811.

4 CODES AND STANDARDS 4.1 Design, Fabrication and Operation General Atomics (GA) is the prime contractor for the design and supply of the SGE experimental facility structures , systems and components (SSC). The SGE experimental facility will be designed and fabricated in accordance with applicable codes and standards , specifically:

• The SGE experimental facility structures, systems and components (SSC), and conduct of operations with the facility , shall comply with all applicable USNRC reactor license requirements, other federal regulatory requirements , as well as local and state design codes and standards requirements .

• SGE experimental facility components shall be designed to meet the applicable requirements in Section VIII , Div. 1 & 2 of the ASME B&PV Code , 2015 (References 1 and 2).

• Welding shall meet the applicable requirements1 in Section IX of the ASME B&PV Code ,

2015 (Reference 4 ).

• Weld NDE shall meet the intent of the applicable requirements in Section V of the ASME B&PV Code, 2015 (Reference 5).

1 The applicable SSCs of the SGE experimental facility will be designed to meet all the requirements of the ASME code, but will not be code certified SSCs.

17

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17/C

• All materials used in SGE experimental facility components shall meet the intent of applicable requirements in Section II of the ASME B&PV Code , 2015 (Reference 3) .

• Regulatory Guide 2.2, Development of Technical Specifications for Experiments in Research Reactors, U.S . Atomic Energy Commission , November 1973, (Reference 6) .

4.2 Software The nuclear, thermal hydraulic and mechanical design of the SGE experimental facility utilized the following analytical and design software packages.

• RELAP5 to confirm thermal hydraulic parameters of the target assembly, and for analysis of target transient conditions.

• FRAPTRAN for source term calculation verification (transient analysis) o RELAP and FRAPTRAN Accident analysis is reported in GA Doc. No.

30441 R00032 "RELAP Accident Analysis and FRAPTRAN Target Rod Transient Analysis"

• FRAPCON for source term calculation verification (steady state analysis)

• AN SYS Workbench R 16 was utilized for the structural performance analysis for the target assembly o ANSYS Workbench R16 software was tested and verified with GA Doc. No.

30441 R00020 documenting the results of the software with GA computers.

o For the fluid analysis portion of the analysis, ANSYS FLUENT was tested and verified with GA report 30441 R00028 documenting the results .

• SolidWorks 2016 for the detailed mechanical design and 3D visualization .

The use of all software for the development of the SGE experimental facility has been subjected to the rigorous software quality assurance (QA) verification and validation procedures as required by the GA Quality Assurance Program and related documents (QAPD-30441-11), including preparation of verification and validation reports as required by the applicable requirements in the applicable engineering procedures in Reference 1.

5 DESIGN INPUTS The Target Assembly (TA) geometry design and dimensions are based on "Molybdenum-99 Supply System Requirements Document", Doc. No. 30441 S00001 and is described in Section 5.1 . Design conditions for specific assembly components are summarized in Section 5.1.

Materials of Construction for the main assembly components are listed in Table 3 in Section 6.

There was no corrosion allowance for the design (preliminary test samples placed inside the 18

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 /C MURR Pool only showed appropriate levels of oxidation). Images documented are on APPENDIX A.

5.1 Mechanical Design The target assembly (TA) is designed to be installed in one or more of the reactors graphite reflector positions . A maximum of two TSs - #5A and #58 - will be installed as part of the SGE facility . Each TA consists of a water inlet section, a target housing , a lower plenum , a cartridge assembly, an outlet diffuser, and a cartridge locking mechanism. Figure 4 shows the TA components. The modeling and mechanical design of the TA components in 30 was performed using the commercially available SolidWorks 2016 software package while the analysis of the components was performed with ANSYS Workbench R16 (30441 R00020) of which results are presented in Section 7. The Target Assembly design pressure inputs Will vary across the sub-components due to the pressure drop that the cooling water will see as it moves through the system . To quantify the actual pressures each component will see during normal operating conditions, an ANSYS Fluent Analysis model was developed to calculate this pressure drop. All of these calculations and parameters are detailed in Doc. No. 30441 R00038. Figure 15 was made by extracting the pressure drop parameters from 30441 R00038 for reference for the 100%

& 115% flow cases . Section 7 has the detailed stress analysis for all components in the Target Assembly.

The water flow enters the target housing through a 3" pipe that is called position one in Figure 15 below (position 1). The flow makes its way through the housing and around the lower plenum and makes its way up, through the lower part of the cartridge flange (position 2). The flow then moves around the grid features that keep the target rods concentric to the cartridge water channels and reach the cartridge main target cooling zone (position 3). The flow makes its way around the targets, cooling them until it reaches the top of the cartridge (position 4) and makes its way through the cartridge top flange grid that holds the target rods in place. Once outside the cartridge (position 5), the diffuser assembly takes over and guides the water flow to the eventual exit location and into the pool (position 6). For this analysis, the pool pressure at the exit of the diffuser is 0 psi meaning that the pressure loads are the difference between the total pressure and the Outlet Static Pressure of the Target Assembly. The pressures for the target assembly loading are summarized in Figure 15.

19

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017 IC Pressure Drop for 100% & 115% Flow Conditions for Target Assembly Flow ...,_ Design Limit Load (psi)

~ Nominal (100% flow)

- Maximum (115% flow) 20.00

'iii

.e 15.00 ~

...:::s QI

~

~

...~ 10.00 5.00 0.00 0.00 1.00 2.00 3.00 4.00 5.00 Target Assembly Position Figure 15. Total pressure minus outlet static pressure cooling water through target assembly from point 1 to 6 at 100%, 115% flow vs max design conditions. Taken from 30441R00038.

These numbers are the maximum loading design parameters for the housing and the cartridge.

21 .5 psi [148.23 kPa] for the Housing and 14.8 psi [102.04 kPa] for the cartridge are maximum loading conditions (at locations shown) that meet the ASME B&PV Code allowables as defined by Figure 15 in Section 7.1 as well as maintaining a minimum factor of safety of 2 per NUREG 2.2 (Reference 6). Although it is not expected to see values above the 115% flow case, these design values are 25.8% (for the Housing) and 21.7% (for the cartridge) higher than the 115%

flow case, more than satisfying the requirements. The detailed stress analysis results for all the TA components are presented in Section 7.

Table 2: Target Assembly Loading Loading (psi) Loading (kPa)

Max Design Pressures for Housing 21.5 148.23 TA components Cartridge 14.8 102.04 5.1.1 Target Housing Figure 15 shows that the ANSYS FLUENT analysis (30441 R00038) yielded a pressure of 17.42 psi [120 .11 kPa] for the highest flow case of 115%. The Target Housing however will be analyzed for the loading condition from Table 2 and a factor of safety will be obtained by 20

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17JC comparing the Target Housing stresses to the ASME Ultimate Tensile Strength allowable at temperature to see that it satisfies NUREG 2.2 (Reference 6) as defined in Section 7.1 below.

5.1.2 Cartridge Assembly Figure 15 shows that the AN SYS FLUENT analysis (30441 R00038) yielded static a pressure of 12.16 psi [83 .84 kPa] for the highest flow case of 115%. The actual pressure drop though the target rods and the cartridge is 3.28 psi [22.61 kPa] (between positions 3 and 4) , the rest of the pressure drop comes from the target rod support flange on the outlet of the cartridge and diffuser (positions 5 - 6). The Cartridge Assembly will be analyzed for the loading condition from Table 2 and a factor of safety will be obtained by comparing the Cartridge stresses to the ASME Ultimate Tensile Strength allowable at temperature to see that it satisfies NUREG 2.2 (Reference 6) as defined in Section 7.1 below.

5.1.2.1 Target Rods Per design requirements (30441 S00001 ), target rods can be irradiated over a 3 week period before they are pulled for further processing , with mid-week and end of week shutdowns over that period . The reactor nominal operating power is 10MW (100%). Though unlikely, the reactor can conceivably drift up to 11. 5MW (115%) reactor power before the control system will take action and lower the control blades .

To look at pellet-cladding interaction, hence pellet thermal and cladding structural performance ,

the target rods were analyzed using FRAPCON. The analysis was performed for three different U02 to Cladding gap sizes , - (Min .), 50 µm (Norn .) and - (Max.), for a 3 week ~

operational period , with the reactor power being set at 100%, except of the first and last day,

~

where the reactor power is assumed to be at 115% for conservatism. This sequence provides the most conservative results for temperatures, fission gas release and relocation . For further details refer to Section 7.2.2.2.

To look at vibration of the target rods, and according to the report ANL-GenlV-070 - Generation IV Nuclear Energy System Initiative Pin Core Subassembly Design , p. 57 (Reference 7), there are two primary concerns from the viewpoint of vibration analysis: i) the magnitude of turbulence-induced target rod displacements (i.e., preclude rod-to-rod contacts which could result in damage accumu lation over the course of plant operations); and ii) excitation mechanisms, wherein the frequency of flow field oscillations may match the natural vibration frequency of the target rods, resulting in energy extraction from the flow field that can lead to rod damage. These two points are addressed in Section 7.2.2.2.3.

Bowing of the RB-MSS target rods due to thermal and irradiation effects was analyzed using ANSYS with a combined thermal-structural model. A thermal analysis of a single target rod was 21

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 IC performed to generate a temperature distribution in the cladding . This temperature distribution was imported into a static structural model to observe the effects of thermal strain on the cladding.

The structural model was then adjusted to incorporate the effects of irradiation induced swelling by modifying the coefficient of thermal expansion of Zircaloy-4 . Results of this analysis can be found in APPENDIX B of this report.

5.1.2.2 Diffuser The diffuser has been made a direct subcomponent of the cartridge assembly to facilitate the handling and exchanging of the target rods. As part of the design , the cartridge and diffuser are intimately attached while down in the reactor position. In order to remove the cartridge, a lifting eye is machined to the diffuser assembly, subjecting the diffuser structure to hold the full weight of the cartridge and target rods . The full weight of the cartridge with 11 target rods is 17 .95 lbs (8.16 kg) which yields a minimum design weight load of 80.05 Newtons that the Diffuser must be able to lift. A structural model was generated for the Diffuser weldment and the results are summarized in Section 7.2.2.3.1. The flow characteristics that the diffuser imparts on the cartridge exit flow are also detailed in 30441 R00038.

5.2 Thermo- Hydraulics Summary A full thermo-hydraulic analysis was performed to evaluate the flow needs of the target assembly as well as the pressure loads the Target Assembly will experience during normal operations and for accident scenarios such as loss of cooling. The full details on the thermo-hydraulics results can be found in 30441 R00021 .

6 ASSUMPTIONS The following assumptions were used in the structural-mechanical analysis:

1. No strength reduction was assumed as a result of irradiation based on the effect of neutron irradiation analysis performed on GA Doc. No. 30441 M00029.

2. There was no corrosion allowance for the design (preliminary test samples placed inside the MURR Pool only showed appropriate levels of oxidation). Images documented on email from Christopher Dohm titled "Corrosion Samples Monthly Update" sent on September 20 , 2016 , (Reference 8) of which a few sample images are appended to this document in APPENDIX A.

3. All TA components (except for the target rod components) are < 50°C, obtained from Doc.

No. 30441 R00021.

4. Materials of construction are as listed in Table 3.

22

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017 JC Table 3: Materials of Construction Target Housing Weldment UNS A96061 Lower Housing Weldment UNS S31603 Cartridge Lower Flange UNS A96061 Cartridge UNS A96061 Lower Diffuser UNS R60804 Lower Cladding Endcap UNS R60804 Cooling Line Flange C-Seal lnconel 718 95% Dense LEU ,

Pellets Y12 Standard S12ecification

5. The target assembly is expected to run and irradiate targets at most twice per week.

6. For the cladding , startups, shutdowns and changes in power are assumed to occur over a 0.05 day (1 .2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) time period . Also, the extreme allowable conditions of the target rods are assumed for the analysis (i.e., the first and last day of a - irradiation is at ~

115% power). ~

7. The total Cartridge pressure cycles are 104; based upon two cycles per week for a total of 1 year lifetime. No thermal cycles are assumed for the Cartridge .

8. The total Target Housing pressure cycles are 1,040; based upon two cycles per week for a total of 10 years. No thermal cycles are assumed for the Housing

9. Cladding cycles are based on a - operation

~

7 STRUCTURAL ANALYSIS OF TARGET SYSTEM ~

7.1 Material Allowables The allowable stress for AL6061-T6 and Stainless Steel 316L were obtained from Section II of the ASME B&PV Code (Reference 3), (Figure 16). These values will be used to evaluate safety and the limits of the Target Assembly components . Values for Zircalloy-4 were taken from Matweb (Reference 9) and in Table 4 , a comparison is done to some of the material strength numbers as used by FRAPCON .

23

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculati on Report 30441 R00017IC As a secondary check , Regulatory Guide 2.2, Reference 6, states :

a. Regulatory Guide 2.2, Developmen t of TS for Experiments in Research Reactors (referenced in NUREG-1573)

Under Mechanical Stress Effects (C.1.c(3)) :

Materials of construction and fabrication and assembly techniques utilized in experiments should be so specified and used that assurance is provided that no stress failure can occur at stresses twice those anticipated in the manipulation and conduct of the experiment or twice those which would occur as a result of unintended but credible changes of, or within, the experiment.)

To satisfy this condition , a minimum factor of safety of 2 will be applied to ensure no stress failure occurs in the Target Assembly components.

120

.....

• 316l SS 100

• 6061 Al (T6}

. : :~: :.*... ~-

'(;"

a.

~

ao

~

Cl) ........

c 60

..2 40 **.

a:

2.0 0

0 50 100 150 2.00 250 300 350 400 450 500 Temperature (°C)

Figure 16: Allowable strength temperature Al 6061T6 and SST316L from ASME B&PV.

24

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 /C Table 4: Zircaloy - 4 Zirconium Alloy, UNS R60804 from MatWeb.com Vs FRAPCON Physical Properties Metric English Comments FRAPCON Density 6.56 g/cc 0.237 lb/in 3 6.52g/cc Mechanical Properties Metric English Comments FRAPCON Tensile Strength, Ultimate >= 413 MPa >= 59900 psi

>= 241 MPa >= 35000 psi Tensile Strength, Yield

@Strain 0.200 % @Strain 0.200 %

Elongation at Break 20% 20% in 50 mm Modulus of Elasticity 99.3 GPa 14400 ksi 81.5 GPa Poissons Ratio 0.37 0.37 0.42 Shear Modulus 36.2 GPa 5250 ksi 30.2 GPa Electrical Properties Metric English Comments FRAPCON Electrical Resistivity 0.0000740 ohm-cm 0.0000740 ohm-cm Thermal Properties Metric English Comments FRAPCON 6.00 b!mLm-°C 3.33 l:!inLin-°F CTE, linear @Temperature @Temperature 25.o 0 c 77.0 °F 0

Specific Heat Capacity o.285 JLg- c 0.0681 BTULlb-°F 149 BTU-inLhr-ft 2 -

Thermal Conductivity 21.5 WLm-K OF Melting Point 1850°c 3360 °F Boiling Point 4375°c 7907 °F 25

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C Table 4: Zircaloy - 4 Zirconium Alloy, UNS R60804 from MatWeb.com Vs FRAPCON Component Elements Metric English Comments FRAPCON Properties Chromium , Cr 0.10% 0.10%

Iron , Fe 0.20% 0.20%

Oxygen , 0 0.12% 0.12%

Tin , Sn 1.40% 1.40%

Zirconium , Zr 98.50% 98.50%

7.2 Results 7.2.1 Target Housing 7.2.1.1 Housing Structural A model was developed to evaluate the structural behavior of the housing assembly to ensure that the design can safely handle stresses when submitted to pressures that more than satisfy the nominal 100% and 115% flow conditions as outlined in Section 5. Taking the highest flow condition of 115% flow during the SCRAM of the reactor, the pressure the housing will see is calculated to be 17.42 psi [120 .11 kPa] taken from Figure 15. Although it is not expected for the Housing to see pressures beyond the 17.42 psi [120 .11 kPa], which occurs at 115% flow, the 21 .5 psi [148 .24 kPa] parameter is set as the design limit of the housing due to the stresses seen at the welds of the housing getting close to the stress allowables as defined in Figure 16 and with a knockdown factor applied due to the type of weld used .

At this 21 .5 psi [148.24 kPa] pressure , the Target Housing performs very well as the maximum Von Mises stress generated is 8.75 ksi [60 .317 MPa] localized at one of the corners of the Aluminum housing as seen in Figure 17a1 and 17c, and which is well within the allowable of 11 .99 ksi [82.7 MPa] for AL6061 per Figure 16. The Von-Mises stresses for the SST316L housing components are below 5.80 ksi [40.00 MPa] as seen in Figure 17a2 for the most part on the main plenum body . There is a high point at a corner of the SST plate that reaches 8.39 ksi [57 .815 MPa ] as seen on Figure 17a2 but it is highly localized and still under the allowable of 24.95 ksi

[172 MPa].

The linearized stresses at the high stress point of the housing, through the back wall and the side-plate weld location of the housing are shown in Figure 18. These stresses show a membrane plus bending value of 3.93 ksi [27 .07 MPa], which is well below the 11 .99 ksi [82 .7 MPa] ASME 26

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17JC code allowable from Figure 16 and providing a factor of safety of 8.90 for the Housing when compared to the 34.95 ksi [241 MPa] yield for AL6061 , more than satisfying NUREG 2.2 (Reference 6).

Per the guidelines from ASME Code Section Ill Div 1 Table UW-12 (Reference 10) type 3 weld ,

"single welded butt joint without the use of a backing strip" will be used on the welds for the housing. To satisfy the code , the weld joint cannot see stresses which are 60% of the allowables.

Sixty percent of 82.7 MPa is 49.62 MPa or 7.20 ksi allowed at the weld location. The membrane plus bending stress at the weld is 3.93 ksi [27 .07 MPa] which more than satisfies the limit outlined by Table UW-12 with the knockdown factor for the welding of the housing . This design limit is still very conservative as evidenced by the safety factor of 8.9 when compared to the yield for AL6061 on top of the 25.80% conservatism taken by designing to a higher pressure load .

The displacement generated by 21.5 psi [148 .24 kPa] load is also small at 0.021 in [0 .526mm]

located at the center of the Housing and seen in Figure 17b. This slight expansion of the Housing does not cause it to interfere with the outer walls of the reactor nor touches the neighboring wedge , which retain a nominal spacing of 0.062 in [1 .57mm] and thus poses no issue.

Figure 17. 21 .5 psi design conditions model for the housing assembly, stresses and deflections 27

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C 1.

S8.95 Membrane (MPa) so. Bending [MP1) 40.

Mtmbr1nt+Btndinq [MP1]

l 30.

. Puk(MP1)

Total [MPa]

~

20.

10.

1.8398<-13

o. 5. 7.5

10. l3.2

[mm)

Figure 18. Linearized stress near corner for 21 .5 psi [148.24 kPa] pressure design condition structural model for the housing assembly 7.2.1.2 Housing Fatigue The Housing is designed to last a period of ten years . The highest number of expected cycles the housing will experience during that timeframe is ~ 1,040 cycles based on current experiment plans that allow up to twice a week cycles. At the design pressure of 21 .5 psi (148 .24 kPa] for the housing, the primary stresses are well within yield strength of the SST316L (24.95 ksi (172 MPa] at 40°C) and for A l6061 T6 (34 .95 ksi (241 MPa] at 40°C) . Also , due to the low amount of cycles and low primary stresses , pressure fatigue is not an issue as seen in Figure 19 and Figure 20 for both materials. Fatigue for steel does not start to become an issue until the cycles reach 100,000 as seen in Figure 19, and for Al6061 T6 , the stress levels of concern at 1000 cycles is at 27 .56 ksi (190 MPa]. The highest stress point for the housing Aluminum components under 21.5 psi (148.24 kPa] loading is localized at the corner of the housing with a Von Mises stress of 8.75 ksi (60 .317 MPa] (Figure 17a1) yielding a safety factor of 3.15. With the low number of cycles not being a concern, the yield value for SST316L is 24 .95 ksi (172 MPa] and comparing this to the high point of stress for the SST316L components being 8.39 ksi [57 .815 MPa] from Figure 17a2, a safety factor of 2.975 is achieved . Thermal fatigue is also not an issue for the housing as the expected thermal difference experienced by the housing will be only 10°C as compared to the pool temperature .

28

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 /C Ctita11 ror lhc UK ol !hf Cunts In Thh F6f&n Ei.Ht li: Anllrtls ol MMtr.aJ Olhtt E~ k Mll:fllf. of Wftd\ llllCI CIW'l'C TllM W*lti ...... Hut Atftcitd lDntS HNI AUKtH hM>t 111, ... 1',. *fl';r.,-tJt S INMPt l P, . ,,, _. (11 ,* * , l .. M,1111d s.

ctnUtul tor ll9flfltd fN,n 111" '

l l'r

• r,.* (/J r1intt > IUMP*

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......... c,...1 100

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• l 9' II to' Mf'I lbl T.tlltt)ollOl~&.llMMtdt.M..tib1.t11U~......,,_llllli"lot...,.~

(cl n..-.ait1e._.ftmtiHrt9Uk~ fttMaci.IMl&t,......*dl!ltf.,.nt......,.trairtl Q.

ICI Oi<W Ah 1Y. l9 tit vwd ll'lltl lllldMl< .na,Ysfs W'UI $*

• 1~~ . _ . *'Jh It* MUI tff<<.I ~ 1tr1'* , ....

,. , n. _ ......wn tthd. .. IW"ollinrd lo:f'nS " Int!...... Qfcw c.

FJG. S*ll0.2.2"4 DESIG N FATIGUE CURVE FOR SERIES 3XX H"H AllOY STEElS, NICKEl-CHROMIUM- IRON AllOY, NlCKEl- IRON-CHROMI UM AllOY, AND NI CKEl-COPP t R AllOY FOR TEMPERATURES NOT EXCEEDING 427"C AND SA~ 195 MPa <USE FIG. S.110.2.l FOR s.. > 19S WP.ti)

Figure 19. SST316L fatigue curve from ASME code (Reference 11) 500 2

200 0.)t.

100 i 10~

-.,=

0 50 - 0 CD as 20 ithmBxfmum an s~ress I t

iii i

• ~ s Number of cycles, N Nate. i:::

• 10* 0 x 10 ps1 Figure 20. Aluminum 6061-T6 fatigue curve taken from "Fatigue Design Curves for 6061-T6 Aluminum" (Reference 12) 29

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017/C 7.2.1.3 C-seal Analysis In order to make the housing body meet the 10 year lifetime requirement, the cartridge to housing interface was identified as key due to the small guiding features that mount and install the cartridge into its final position as well as the size of the bypass prevention features. With this in mind , the decision to use SST 316L on the male features and Aluminum 6061 on the female features was made. However, due to the half-life of SST316L once activated and its associated cost for disposal, the use of SST316L is minimized to create an interface back to Aluminum 6061 for the main housing body. This interface between the aluminum body of the housing and the steel lower portion is sealed with a c-seal. The c-seal prevents water leakage and allows the use of the two materials. Manufacturer Jetseal Inc. was contacted to design a c-seal for the geometry provided and that would seal the surfaces up to 21 .5 psi [148 .24 kPa]. A model was generated to measure the deflections the flange will have under the load from the bolts compression of the c-seal and from the scenario were someone leans into the pipes at the top of the pool. Due to the long lever (- 6.5m), small forces could potentially cause enough deflections in the housing to cause lift from the c-seal in the flange. The manufacturer has a recommendation of 250 lb/in of linear force around the seal to be used and that is what was loaded into the model.

To make sure this flange is stiff enough and the interface has no leakage due to deflections from the flange, an FEM was generated with the following loads: a) 21.5 psi [148 .24 kPa] internal pressure with a 2000 lb/bolt preload [8896.44 Newtons/bolt], b) a 2501bs/in linear force on the c-seal groove (resistance from the c-seal), and c) a 21244 in*lbf [2400N*m] moment to simulate an average size man leaning on the water inlet pipe at the top of the pool (78. 71bs/35.7kg lateral load). Figure 21 shows the geometry of the lower housing flange with a 13-bolt configuration .

Figure 21. Geometry of the lower housing flange with a 13 bolt configuration 30

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC Figure 22 shows the deflections of the flange and the groove under the pressure and the moment loads. Deflections are minimal as expected due to the flange thickness of 0.75 inches in addition to the flange ribs providing a great amount of stiffness perpendicular to the mating flanges . The maximum deflection is 0.0065 inches [0.165mm] from point to point on the sealing surface of the groove under the load . The c-seal is designed with at least 0.013 inches [.3302 mm] elastic springback in order to prevent lift and avoid water bypass under these loading conditions and maintain a factor of safety of 2.

Although the 3" inlet pipe will be at ground level at top of the pool to avoid someone leaning on it, this extra level of robustness serves as margin for the expected loading of the design.

31

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017IC 1

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Figure 22. Deflections of the c-sea/ flange and groove under pressure and moment loads As far as the stresses on the housing are concerned , Figure 23 shows the load of 2700N applied to the top of the housing. This is the equivalent of a 40kg/88.181bs load being applied to the top of the line 22.4 7 feet [6.85m] above the housing , mimicking the weight of a person leaning on the pipe at the top of a pool and to show that the housing is more robust than the lift moment applied when analyzing the c-seal. Figure 23 shows the maximum Von Mises stress calculated from this load is 11.60 ksi (79 .97 MPa] for one of the ribs on the lower flange and around 9.14 ksi (63 MPa]

at the 3 inch inlet and top plate of the housing . Under these conditions , having half the weight of 32

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC an average person leaning on the pipe , the TA meets the allowable from the ASME code for AL6061 at 11 .99 ksi [82.7 MPa]. It is the intention to institute procedures and administrative controls* to not have a person lean on the pipes such as anchoring the pipe to a support structure at the top of the pool for support so that the support takes the load from someone accidentally leaning on the pipe but this analysis shows that the design can take a significant lateral load without damaging the housing .

ZU1 U.111 U'4l 1.82127Mn Figure 23. Radially outward load. 88. 181bs/40kg equivalent at top of pool 7.2.2 Cartridge Assembly 7.2.2.1 Cartridge 7.2.2.1.1 Cartridge Structural A model was developed to evaluate the structural behavior of the cartridge assembly to ensure that the design can safely handle stresses when submitted to pressures corresponding to the nominal 100% and 115% flow conditions. Taking the highest flow condition of 115% flow during the SCRAM of the reactor, the pressure the cartridge will see is calculated to be 12.16 psi [83.84 kPa] taken from Figure 15. Although it is not expected for the cartridge to see pressures beyond 33

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017/C the 12.16 psi [83 .84 kPa] which occurs at 115% flow , the 14.80 psi [102.04 kPa] load parameter is chosen as the design limit of the cartridge due to the stresses seen by the pins under the load and to maintain a minimum safety factor of 2 on those stresses to the yield of SST316L per the code .

The aluminum cartridge at the 14.80 psi [102 .04 kPa] pressure fairs very well overall with the pins taking most of the load. Figure 24 shows most of the cartridge experiences very low Von Mises stress levels hoovering at 10.45-1. 74 ksi [10-12 MPa]. The inside wall and small localized areas around the pins are the zones that see higher stresses. The cartridge sees total stresses up to 18.40 ksi [126 .83 MPa] in highly localized areas around the pins but only 8.99 ksi [62 .03 MPa] 1 mm deep into the cartridge main body as evidenced in Figure 25 when linearizing the stresses through the cartridge wall. At these locations around the pins , the membrane plus bending stresses through the cartridge wall of 8.45 ksi [58.25 MPa] as seen in Figure 25, show the design satisfies the ASME Code allowable of 11.99 ksi [82.7 MPa].

nM 5'.JA 42.27' ZUl5 I.UH l.001225 ...

Figure 24. Cartridge at 14.80 psi design pressure condition. Stresses and deflections 34

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017 JC 6.7427 Figure 25. Cartridge at 14.80 psi design pressure condition. Linearized stress through cartridge wall Figure 24 also shows the deflections under the 14.80 psi [102 .04 kPa] load . The maximum calculated displacement of 73 .7 microns occurs at top of the cartridge . The displacement generated by this pressure is small by design due to the placement of the pins which prevent large volumes of the cartridge body to balloon out, ensuring that the velocity from the cooling water around the target rods remains constant.

At the side walls , the cartridge see lower stresses than around the pins but just like in the Housing ,

and because the cartridge is fabricated as a clamshell halves, the strength at the weld seam must have a knockdown factor of 0.6. This brings down the allowable for AL6061 from 82.7 to 49.62 MPa or 7.20 ksi. As seen in Figure 26, the stresses at the inner surface have a high point of 6.36 ksi [43.88 MPa] but when linearized through the wall at this location, the membrane plus bending totals 2.98 ksi [20.55 MPa]. This satisfies the design welding limit due to the knockdown factor for the welding of the cartridge sides. In order to meet the ASME Code, the 14.80 psi [102.04 kPa] pressure is set as the limit for the design, due to the SST316L pins stresses and keeping a minimum factor of safety of 2 as shown in Figure 27.

35

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC 20.188 Membrane (MPaj

16. Bendinq ( Pa)

Membrane+Bendinq [MPa]

l 12.

• Peak{MPa]

r!

a.

4.

Total (MPa}

0. ---.-- T -

0. 0.4 0.8 1.2 1.6 2. 2.4

[mm]

Figure 26. Linearized stresses of cartridge through at weld location for 14.80 psi loading conditions As mentioned earlier, the pins by design are meant to take the brunt of the pressure load. Figure 27 shows that one of the pins sees a maximum Von Mises stress of 24.76 ksi [170.71 MPa] at the local point of contact and node shared with the cartridge's high point. As evidenced by the stresses on the rest of the pin and the linearization plot through the center of the pin it is clear that this high stress number is from the geometric discontinuity in the model of the cartridge coming to a point and meeting the pin. This is a self-limiting stress that does not affect the pin performance . When linearizing the stresses through the center of the pin , stresses of 13.89 ksi

[95 .83 MPa] are seen, but when broken down to the primary stresses through the middle of the 36

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC pin, the shaft only sees 8.66 ksi [59.71 MPa] when adding the membrane and bending stresses which are still below the 16.68 ksi [115 MPa] allowed.

14.316 0.1112196 Min Bencf1119 (MP*J - -

9S.826 Mtmbr*,,.,.Btndinq (MP*)

. Puk (MP*)

7S. lot.it{MP*l

'j so.

~

25.

o. r I

0. 4. 8. 12. 16. 20. 24 . 29.261 (mm)

Figure 27. Cartridge at 14.80 psi design pressure condition. Pin maximum linearized stresses The cartridge aluminum components maximum primary stress value is 8.45 ksi [58.25 MPa ] as mentioned above in Figure 25. At this stress value , the cartridge aluminum parts have a 4.14 factor of safety when compared to the 34 .95 ksi [241 MPa] yield for AL6061 , more than satisfying NUREG 2.2. The SST316L pins see higher stresses as designed, with the highest pin seeing 8.66 ksi [59 .71 MPa] primary stresses. The yield for SST316L is 24 .95 ksi [172 MPa] per the already conservative ASME code which provides a 2.88 factor of safety to yield . However the 14.80 psi [102.04 kPa] load is already 21 .7% higher than the highest expected value at 12.16 psi

[83 .84 kPa]. In order to maintain a minimum safety factor of 2 to yield and keep good margin in satisfying NUREG 2.2 (Reference 6) , the loading of 14.80 psi [102 .04 kPa] is set as the limit for the housing components. Although the NUREG 2.2 regulation states that the design must maintain a factor of safety minimum of 2 to failure, all of the design parameters for the target assembly are meeting this requirement to the yields of their materials for the extra margin .

37

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017 JC Since the design pressure of 14.80 psi [102.04 kPa] for the cartridge shows the factor of safety to be over 2.88 to yield for the pins, and in order to have added margin, the 14.80 psi loading parameter was conservatively chosen as the maximum. This same model was calculated for the actual design pressure expected at the 115% SCRAM condition of 12.16 psi [83 .84 kPa]. Figure 28 below shows the results for a loading of 12.16 psi [83.84 kPa] on the cartridge . The pins see a maximum localized stress 20.35 ksi [140 .29 MPa] in the same pin-cartridge high point location as mentioned for the 14.80 psi loading case. When the stresses are linearized through the center of the shaft, the maximum bending plus membrane stresses are 7.12 ksi [49 .07 MPa]. This yields a factor of safety of 3.51 to the yield of the SST316L allowable from the already conservative ASME code.

o. a.

'* 12.

[mm)

16. 20. 24. 29.261 Figure 28. Cartridge at 12. 16 psi design pressure condition (115% max flow). Pin maximum linearized stresses

• 7.2.2.1.2 Cartridge Fatigue The cartridge is designed to last a period of one year. The highest number of expected cycles the housing will experience during that timeframe is < 104 cycles based on current experiment plans. At the design maximum design pressure of 14.80 psi [102.04 kPa] for the cartridge, the primary stresses are still within the code allowables and the yield strength forthe SST316L (24 .95 ksi [172MPa] at 40°C) and for Al6061 T6 (34.95 ksi [241 MPa] at 40°C) components . This gives the cartridge plenty of margin over the maximum expected stresses seen at the 115% flow 38

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C condition. Also due to the low amount of cycles, and low primary stresses , fatigue from the pressure load is not an issue as seen in Figure 19 for the stainless steel as it takes one million cycles before the onset of material fatigue and Figure 20 which sees the aluminum barely begin to see material fatigue at the expected 104 cycles. With the maximum aluminum stresses at 8.66 ksi [59.71 MPa] for the 14.80 psi [102.04 kPa] pressure case (from Figure 25), as seen in the curve from Figure 20 for this number of cycles , stress in not an issue. Thermal fatigue is also not an issue for the cartridge as the expected therma l difference experienced by the housing will be only 10°C.

7.2.2.1.3 Cooling Flow 7.2.2.1.3.1 Target water flow velocities The coolant velocity distribution is important to ensure that all rods receive adequate convective heat removal. An ANSYS FLUENT (30441 R00038) model was developed for the pinned cartridge design to evaluate the effect the pins would have in the water channel. The full details of the analysis are shown in 30441 R00038, where the document shows that the flow has reached *

. and it is within - of the 5m/s target ~

velocity a sixth of the way up the cartridge. From the contour plots , it is clear that the pins slow

~

the flow down in the channels they reside in . However, in most cases the flow still remains above

~

the - in all channels, and never drops below - (. below the target velocity) . Given the margins calculated for the heat transfer and the localized nature of these velocity reductions ,

the simu lation indicates that the flow distribution in over the target rods is sufficient to provide the ~

necessary cooling.

7.2.2.1.3.2 Target water exit temperature and mixing Another function of the diffuser is to mix the coolant flow exiting the 11 channels and provide a good thermal measurement of the water exiting into the pool. The design calls for an RTD to be inserted to the top of the diffuser to take this measurement. To evaluate that the shape of the diffuser does indeed provide adequate mixing , 30441 R00038 shows the temperature contour plot that was created at the same elevation as the tip of the RTD sensor. Results show the coolant ~

temperature around the RTD varies by less than -

• exhibiting sufficient mixing to accurately ~

detect mixed mean coolant outlet temperature.

7.2.2.2 Target Rods 7.2.2.2.1 FRAPCON Analysis Pellet-clad interaction and the resulting stresses and strains on the cladding were analyzed using the computer code FRAPCON (References 13 and 14). FRAPCON-4.0 is the latest version of FRAPCON released September 2015. Patch 01 of FRAPCON-4.0 was released June 2016 and was used in all of the following calculations.

39

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017IC FRAPCON was developed by Pacific Northwest National Laboratory (PNNL) for the U.S. Nuclear Regulatory Commission (NRC) to calculate steady-state, thermal-mechanical behavior of light water reactor (LWR) oxide fuel rods . Phenomena modeled by the code include heat transfer through fuel and cladding to coolant, cladding elastic/plastic deformation , fuel-cladding mechanical interaction , fission gas release and rod internal pressure , and cladding oxidation.

FRAPCON is used by the NRC as an independent audit tool in their review of LWR industry fuel performance codes . FRAPCON has been assessed against experimental data from 137 test cases (Reference 13).

Three analysis cases were examined with FRAPCON based on the gap size between the U02 pellet and the Zircaloy cladding : minimum gap of -

• nominal gap of 50 µm , and maximum If5a , b, I gap of - . The three FRAPCON cases have the following file names with either *. inp for input,

• .plot for plot file , or *.out for output.

frapcon- -100_ 115_38 frapcon-50_ 100_115_38 frapcon- -100_ 115_38 These gap sizes are a result of allowable tolerances on the pellet outer diameter and cladding inner diameter. The geometric dimensions that define the FRAPCON analysis cases are presented below in Table 5.

Table 5: Geometric Dimensions Used in FRAPCON Analysis Pellet outer diameter 5.0000 mm Clad inner diameter 5.1000 mm Clad thickness 0.5000 mm Clad outer diameter 6.1000 mm Scallop diameter 0.583 in .

Pitch 0.458 in.

The specific target rod analyzed in FRAPCON is target rod 17 (from wedge 5B . See 30441R00031), which has the maximum power density and, therefore , the maximum local heat flux . FRAPCON uses an axial power distribution and a rod linear power to model the behavior of ~ 5a , d, target rod 17 over a - irradiation period with mid-week and weekend shutdowns . In order e

to examine the target rod behavior at extreme allowable conditions , the first and last day of the I

. . irradiation is at 115% power. At all other times the target is at 100% except for the shutdown periods when the target is generating decay heat from the buildup of fission products . The power history used in the FRAPCON analyses is shown in Table 6 .

40

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 R00017 IC Table 6: Power Histories Used in FRAPCON Analyses Problem Time hours 1.2 24.0 25.2 48.0 73.9 75.1 78.0 79.2 96.0 120.0 151 .9 153.1 5a , d, 168.0 169.2 e 192.0 5a, d, 216.0 241.9 e, f 243.1 246.0 247 .2 264.0 288.0 319 .9 321 .1 336.0 337 .2 360.0 384.0 409 .9 411 .1 414.0 415.2 432.0 456.0 462 .7 463 .9 487 .9 Startups, shutdowns, and changes in power are assumed to occur over a 0.05 day (1.2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) time period. Mid-week shutdowns begin with a 0.05 day (1 .2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) power decrease to 0.0, a shutdown period of 0.12 day (2.9 hour1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />), and end with a 0.05 day (1.2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />) rise to full power. The weekend shutdowns have the shutdown period extended to 0.62 day (14.9 hour1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />).

The linear rod power histories presented in Table 6 are based on a detailed MCNP6 analysis (30441 R00032).

41

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017IC The axial power profiles used in the FRAPCON analyses are presented in Table 7. They are based on a detailed MCNP6 analysis which is then piecewise averaged to the 21 axial elevations used in the FRAPCON model. MCNP6 performance and validation for use in this calculation is detailed in 30441 R00002.

Table 7: Axial Power Profile Used in FRAPCON Elevation (m) Axial Power Factor 0.00 0.952 0.03 1.060 0.06 1.148 0.09 1.214 0.12 1.258 0.15 1.282 0.18 1.307 0.21 1.280 0.24 1.259 0.27 1.227 0.30 1.186 0.33 1.133 0.36 1.069 0.39 0.993 0.42 0.904 0.45 0.804 0.48 0.695 0.51 0.586 0.54 0.489 0.57 0.423 0.60 0.418 RELAP5 Mod 3.3 Patch 03 was used to determine the steady state cladding temperatures at 100% and 115% power for all three FRAPCON cases (30441 R00032). The six RELAP5 cases have the following file names with either *.inp for input or *.out for output.

1thruB_1 O.OMW_-ssnomF 1thruB_11 .5MW- -SSnomF 1thruB_1O.OMW_50SSnomF 1thruB_11 .5MW_50SSnomF 1thruB_10.0Mw_-ssnomF 1thruB_11.5MW- -SSnomF The cladding outer diameter temperatures are presented below in Table 8.

42

Attachment 8 ANSYS Target Cartridge , Housing Structural Ana lysis Design Calculation Report 30441 R00017IC Table 8: Cladding Outer Diameter Temperature for Target Rod 17 Cladding Outer Diameter Temperature Cladding Outer Diameter Temperature Elevation m

0. 00 0.03 0.06 0.09

- 429.47 434.25 439 .11 442 .98 at 100% Power K 50 µm gap 429.38 434.15 439.01 442 .87 424.45 429.45 434.35 438. 18 438.42 442 .85 447.48 451 .24 at 115% Power K 50 µm gap 438.33 442 .74 447.37 451.12 433 .64 438 .03 442 .65 446 .38

[EJ 0.12 445.46 445.35 440.62 453.68 453.55 448 .80 0.15 446.59 446.47 441 .71 454.80 454.68 449 .90 0.18 446.61 446.49 441 .74 454.85 454.72 449 .93 0.21 445.87 445.76 441 .03 454.14 454.01 449 .21 0.24 444.66 444.54 439.86 452 .95 452.82 448.03 0.27 443.13 443.02 438 .36 451.45 451 .32 446.55 0.30 441 .26 441 .15 436 .51 449.63 449.51 444.77 0.33 438.86 438.75 434.09 447 .32 447.20 442.49 0.36 435.56 435.46 430.76 444 .18 444.07 439 .39 0.39 430 .93 430 .83 426.09 439 .80 439.69 435.02 0.42 424.54 424.45 419.68 433.74 433.64 428 .98 0.45 416.15 416.07 411.32 425.72 425.64 420 .97 0.48 405.85 405.78 401.14 415.78 415.70 411 .05 0.51 394.30 394.25 389.85 404.43 404.37 399.79 0.54 383.00 382 .96 378.98 392.95 392 .90 388.55 0.57 374.57 374.54 371 .16 383.66 383.62 379.74 0.60 373.08 373.05 370.48 380.19 380 .15 377.18 Additional input parameters for FRAPCON are listed below in Table 9.

Table 9: Additional FRAPCON Input Parameters Parameter FRAPCON Input Value Plenum length cold 3.9116 cm Plenum spring outer diameter 0.4826 cm Plenum spring wire diameter 0.635 mm Plenum spring number of turns 17 Pellet dish depth 0.12 mm Pellet end-dish shoulder width 0.55 mm Chamfer height 0.08 mm Chamber width 0.24 mm Enrichment 19.75 %

Pellet apparent density 95.0%

Pellet surface roughness 2.0e-04 mm Cladding cold work 0.40 Cladding surface roughness 8.0e-04 mm Rod fi ll qas pressure 101325 Pa FRAPCON results are presented below in four tables, Tables 10 through 13, for the time points in the power history of greatest interest: 0.05 day at 115% power, 1.05 day at 100% power, 43

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C

- day at 100% power, and - day at 115% power. The results are either for the entire ~

5ea , d, target rod or for axial node 6 out of 20 which has the peak power density and heat flux.

Table 10: FRAPCON Results at 0.05 days at 115% Power a 50 m a a Pellet centerline temperature (C) 2204 2326 2515 Pellet surface temperature (C) 359 419 529

~

Cladding ID temperature (C) 302 300 324 Cladding OD temperature (C) 182 182 177 Cladding average temperature (C) 242 241 250 Radial strain(%) 0.009 0.139 0.145 Axial strain (%) 0.169 0.105 0.109 Hoop strain(%) 0.284 0.139 0.144 Cladding internal pressure (MPa) 0.24 0.26 0.27 Cumulative fission gas release(%) 0.00 0.00 0.00 Cladding axial expansion (mm) 0.62 0.54 0.56 Fuel axial ex ansion mm 3.89 4.59 5.50 Table 11: FRAPCON Results at 1.05 days at 100% Power a 50 m a a Pellet centerline temperature (C) 1912 2007 2189 Pellet surface temperature (C)

Cladding ID temperature (C)

Cladding OD temperature (C) 360 279 173 402 279 173 493 298 169 1:** b. I Cladding average temperature (C) 226 226 233 Radial strain(%) 0.022 0.128 0.132 Axial strain (%) 0.127 0.098 0.100 Hoop strain(%) 0.206 0.129 0.132 Cladding internal pressure (MPa) 0.23 0.24 0.25 Cumulative fission gas release(%) 0.00 0.00 0.00 Cladding axial expansion (mm) 0.54 0.50 0.52 Fuel axial ex ansion mm 3.45 3.98 4.67 Table 12: FRAPCON Results at - days at 100% Power 1:** d. I a 50 m a a Pellet centerline temperature (C)

Pellet surface temperature (C)

Cladding ID temperature (C) 1994 351 279 2079.15 393 279 2115 412 298 I:** b. I Cladding OD temperature (C) 174 173 169 Cladding average temperature (C) 226 226 233 Radial strain (%) -0 .106 0.127 0.131 Axial strain (%) 0.188 0.097 0.101 Hoop strain(%) 0.322 0.131 0.136 Cladding internal pressure (MPa) 0.54 0.61 0.70 Cumulative fission gas release(%} 17.74 20.48 21 .61 Cladding axial expansion (mm) 0.66 0.50 0.52 Fuel axial ex ansion mm 3.65 4.12 4.65 44

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017 JC Table 13: FRAPCON Results at - days at 115% Power a 50 m a a Pellet centerline temperature (C)

Pellet surface temperature (C)

Cladding ID temperature (C) 2350 379 303 2359 384 301 2417 418 324 I :a* I d.

Cladding OD temperature (C) 182 182 177 Cladding average temperature (C)

Radial strain (%)

242

-0.495 242

-0.123 250 0.140

[:a* Ib.

Axial strain (%) 0.339 0.1 90 0.109 Hoop strain(%) 0.659 0.386 0.150 Cladding internal pressure (MPa) 0.61 0.70 0.81 Cumulative fission gas release(%) 18.71 21 .79 22.82 Cladding axial expansion (mm) 1.11 0.68 0.56 Fuel axial ex ansion mm 4.17 4.52 5.1 2 7.2.2.2.2 Pellet Clad Interaction Structural Evaluation Summary As discussed in Section 7.2.2.2.1 , "FRAPCON Analysis", the pellet- clad interaction for the target rods has been analyzed using FRAPCON 4.0 to ensure that the target performance does not exceed design limiting factors of fuel melting temperatures and cladding strain cycles. Each target rod, shown in detail in Section 3.2.3.2 consists of 100, 95% dense U02 pellets that are encapsu lated by the Zircaloy-4 cladding. Additionally, the Zircaloy-4 cladding was analyzed with 40% cold work after final annealing during manufacturing .

The pellets (see Figure 29) have been designed for optimum performance with manufacturability in mind. Dishing of both ends was added to minimize ratcheting effects in the cladding , while chamfers were added for ease of insertion and elimination of stress concentrations on the cladding from pellet rotation. The pellet to clad gap was optimized at - nominal to minimize stress/strain in cladding on one hand and peak centerline temperatures on the other. f5a, b,I I When adding manufacturing tolerances, the gap varies between

• and

• microns. Additionally, the target rod void space is fi lled with > 95% He, at ==1 atm , that aids the welding process and provides good heat transfer properties to minimize pellet centerline temperatures.

45

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17IC Chamfer Fuel Pellet 6mm Cladding (nom.)

Dishing Figure 29. Pellet and cladding details A nominal operational scenario suggests that depending on demand, the target cartridge could be pulled from the target housing any time between therefore, it has been assumed that during the -

I of startups and shutdown cycles, I For analysis purposes period the reactor could see a maximum

, though cycles is more likely to be the nominal t:J 5a , d, e

case if operated to the - -

limit. For analysis purposes it is assumed that at the beginning and end of the period, the reactor would run at 115% (11.5 MWt) power for a period of 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. At 115%, control rod run-in initiates and reactor SCRAM occurs at 125% (12.5 MWt).

The result, an upsurge in fission gas release, internal pressure rise, and additional thermal growth and pellet relocation are experienced, though the duration and frequency is not enough to cause any design limit to be exceeded .

The results of the FRAPCON analyses are shown in Table 14; extracted from Tables 10 thru 13 for cases of interest. Stresses and strains as a result of pellet-clad interaction are highest for the ~f5a, b, minimal cold gap ( - ). The results show that for the above operating/design conditions l!____J the primary pressure induced stress is< 5 MPa, and well within the primary stress limit of Zircaloy-4 of 430 MPa (6237 psi) , at temperature (Figure 30) . With a factor of safety of > 90 on primary stresses, the design meets ASME B&PV Code as well as Regulatory Guide 2.2 (C.1.c(3)) of the U.S . Atomic Energy Commission , (Reference 6), which requires factor of safety against failure of

2. Primary stresses are therefore not the driver for cladding failure. Secondary stresses as a result of thermal differential expansion and re-location of the cracked pellet on the other hand are the main drivers for longevity of the cladding. A yield strain for Zircaloy-4 at temperature of about 0.5% is well within the strain range of twice of yield, 1.6%. This therefore meets the secondary stress intensity limit. With respect to cyclic fatigue for Zircaloy-4, Figure 31 [ASTM STP 1245 46

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17/C (Reference 15)], which includes irradiated specimens , shows that the maximum quantity of cycles that the cladding can sustain is 20 ,000 . With only I expected cycles, the cladding has ample design margin .

Table 14: FRAPCON Results Summary Temperature (°C) Gap 50 µm Gap Gap Pellet centerline 2350 2359 2515 Pellet surface 379 419 529 Cladding ID

• • 301

• • 1:** I b.

Cladding OD 182 Cladding Average 242 242 250 Strain(%)

Radial -0.495 0.139 0.145 Axia l 0.339 0.190 0.109 Hoop 0.659 0.386 0.150 Gas Pressure (MPa)

Cladding Internal 0.61 0.70 0.81 600

...

• Zlrc-4 (irradiated) 500 "i *****************

~

400 I ............ ............

~

"' I

~

. 300

~

cc 200 100 I 0

0 100 200 300 400 500 Temperature (°C)

Figure 30. Allowable stress for Zircaloy-4 (irradiated) based on 213rd yield [ ASTM STP 1245 (Reference 15)]

47

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017 IC 1 % stra in ~ *OO . O (ASM E; factor of 2 ~

on stress/strai n) ~

.s.

~

~ o. s Untrr-edi

• t *d 0 0 . 15 HJ 400000 r;ydes e I HZ 0.5% strain o

• cycle* '" EOF PWtt (ASME 20,000 r;ycles; factor of o.

iuoo 10000 1000 - ~oo 20)

Fat t ou* ltfe Nr (CJ'c.l**>

FIO. 1-Cycl~ p/<Jstl< "" "~""',,.. ,..,,.,,.,tiqck1 10 ,.,,,,.,./"1' claddU., 1*1 *11i""410liil or lrrudiartd '""' eyclo ii ** EDF PWR.- ~ ""'"ikd ,,,.a-., wwl rptt;,,,,.., tartJ "' a 70000 cycles

• t a . Strt.JI tlurllt1 1<1 C1'!1n IAH tuwl IJl 41 > a , lt~l.S"" IO !Vplllll.

EJ Figure 31 . Fatigue chart Zircaloy-4, 350°C (un-irradiated and irradiated) (Reference 16 & 17)2 In case of the maximum gap of -

• the upper limit of manufacturing tolerances, the 5a , b, concern is the centerline temperature of the target pellet. The maximum target pellet centerline f

temperature is 2515 °C (Table 14), which will occur at startup when no relocation has occurred. This value is well within the fuel melting temperature of 2840°C.

The analyses show that the target rod meets the design requirements set forth in [30441 S00001]

and can be safely operated under nominal reactor conditions of 10 MWt, including the two (2) 11 .5 MWt excursions at the beginning and end of the The design incorporates I e5a, d, I a safety factor of 3333 for cladding cycles and > 25000 for pressure-induced primary stress cycles. As previously mentioned , the design meets ASME B&PV Code, as well as Regulatory Guide 2.2 (Reference 6). (C .1.c(3)) of the U.S . Atomic Energy Commission with ample design margin. Additionally, the cladding exhibits a thermal margin of safety of> 140°C, while the target pellet exhibits a thermal margin of safety of> 300°C.

7.2.2.2.3 Flow Induced Vibrations According to the report ANL-GenlV-070 - Generation IV Nuclear Energy System Initiative Pin Core Subassembly Design , p. 57 (Reference 7) : There are two primary concerns from the viewpoint of vibration analysis: i) the magnitude of turbulence-induced target rod displacements; (i.e ., preclude rod-to-rod contacts which could result in damage accumulation over the course of 2 The reported values for cycles in Figure 31 were adjusted in accordance to ASME B&PV Code to provide a factor of 2 on stress/strain and 20 on cycles (whichever is more conservative). Per previous statement, with a factor of 2 on stress/strain , ASME B&PV covers the requirements of Regulatory Guide 2.2.This means that in case of 0.5%strain, applying a factor of 2, 1.0% strain , the quantity cycles are estimated at 70,000 , or in case of 0.5% , using a reduction factor of 20, the expected cycles are 20,000 (400 ,000 cycles I 20). Note that these are adjustment factors to the experimental data set to obtain estimates of lives of components; per [NUREG/CR-6815 (Reference 16)].

48

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017IC plant operations) , and ii) excitation mechanisms, wherein the frequency of flow field oscillations may match the natural vibration frequency of the rods, resulting in energy extraction from the flow field that can lead to target rod damage.

To address these two points, two different cases were calculated . In the two cases , the ends are tightly fixed so that they can support a moment in addition to being fixed in xyz directions. The variation for these two cases comes from having the rods be empty or tightly filled, where the rods are full (intimate contact with the cladding) and act to damp the vibrations.

For a 6.67 mis axial flow speed in the cartridge channels, the flow induced vibrations are given in Table 15.

Table 15: Flow Induced Vibration Results Tightly Fixed Rods Natural Frequency Displacement Displacement (Hertz) (Paidoussis) µm (Blevins) µm Empty Rods 59.4629 6.0535 1.3665 Filled rods 47.292 1.0603 0.4221 Through machining tolerance, the minimum gap between the cladding and the pellets will be

-

• With such a close gap it is difficult to gauge how much the pellets do indeed act as a dampener so the empty case was evaluated first. Although the displacement will be smaller B

5a , b, f

due to the mass of the pellets acting as a dampener, looking at the empty case the displacements through both, the Paidoussis and Blevins approach , the relative displacements are very small. At 6 microns, this magnitude of turbulence induced displacement does not pose a threat to the target rods and satisfying the first point from the ANL report (Reference 7) above. As for the second point, the report above also mentions "these types of instabilities are principally observed in situations involving cross-flow across tube banks". The cartridge single row design makes cross flow velocity components very small in the cartridge region as seen in Figure 10 of 30441 R00038.

In this figure , the lateral velocities are formed more as a result of the target rod being in the path of the flow more so than as a reflection of the cartridge design. At such small velocities and the natural frequencies calculated in Table 15, resonance effects from cross flow components are not an issue.

49

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOD 17JC 7 .2.2.3 Diffuser 7.2.2.3.1 Weight Analysis The cartridge assembly design details that the diffuser is an intimate component of the cartridge ,

so much so that the extraction procedure for the cartridge calls for the use of a feature on the diffuser to lift the cartridge assembly. This means the diffuser structure must be able to hold the weight of the cartridge assembly and the target rods within it, and not just be a ducting flow path for the water. An FEA model was created of the diffuser of which the models mesh is shown in Figure 32.

Each target rod has a mass of 0.366 lbs (0.166 kg) when filled with the pellets and there is a total of 11 target rods for a total mass of 4.02 lbs (1 .83 kg). The target rod and the cartridge machined components masses are given in Table 16. Adding these together yields a total mass of 17 .94 lbs (8.157 kg) so that the total load for the diffuser is 80 Newtons.

Table 16: Weight of Cartridge Components Weight of Components Pounds Kilograms Diffuser Ducting 0 .84165 0.3825682 Diffuser lower flange 0.26086 0.1185727 Cartridge upper flange 0.20297 0.0922591 Cartridge Empty with pins 8.3023 3.7737727 5a , b, d, e, f Cartridge lower flange 0.8121 0.3691364 lx Target Rod with Pellets 0.3659 0.1663182 Total for Cartridge with 11 Target Rods filled with Pellets 17.94648 8.1574909 Figure 33 shows the stress plot experienced by the diffuser taking the full weight load of 80 Newtons. The maximum Von Mises stress seen is 2.98 ksi [20 .535 MPa] which is still well below (4.03 times) the allowable of 11 .99 ksi [82.7 MPa].

50

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17 IC Figure 32. Diffuser weight analysis, meshing Figure 33. Diffuser weight analysis, stress results for BON load The pullout force limit for the diffuser is set by the max load the design can take before it begins to yield. Using the same model above , the stresses begin to reach the yield point of aluminum per the ASME code of 34.95 ksi [241 MPa] (Figure 34) when the load reaches just over 940 Newtons. As a result, 850 Newtons is chosen as the maximum pull out force the diffuser assembly can take.

51

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17JC 134.05 107.24 80.431 53.621 Figure 34. Diffuser weight analysis, stress results for 727N load 7.2.3 Handling Tools Handling of the target rods will be done at the cartridge loading station as seen in Figure 2. To get the cartridge assembly to this location, a simple reach tool is threaded into the female cartridge lifting feature seen in Figure 35. Once the locking clamps are disengaged , the reach tool is threaded to the cartridge lifting feature which is at the center of mass of the cartridge assembly.

As mentioned in Section 5.1.2.2 the total mass of a fully loaded cartridge assembly is 17 .95 lbs (8.16 kg) so that the 3/8-16 thread from the lifting feature attached to a similarly 3/8 diameter reach tool is more than enough to lift the total combined anticipated weight of 26.4 lbs (12 kg) for the tool and cartridge . The anticipated stresses and deflections are minimal , in the order of 0.29-0.73 ksi [2-5 MPa] for this size reach tool and the weight of the cartridge assembly.

52

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C Cartridge A.ss.embl~*

locking I g Cartridge Ass.emblv, Diffuser Locking 2x Cartridge Assembly, Locking Mechan ism lo::king/unloc

• ng bolt 4x Cartridge Assembly, Diffuser Locking Meehan* m Spring A eirures Figure 35. Cartridge assembly lifting and locking features 8 RESULTS

SUMMARY

The structural analysis for the target assembly was performed in ANSYS Workbench R16 . The calculations confirmed that the target housing and cartridge components are properly sized according to the ASME B&PV Section VIII, Division 1 and Section 11-D, for normal and off-normal conditions. Based on this analysis, the structural design life of the target housing is conservatively estimated at 10 years while the design life of the cartridge is conservatively estimated for 1 year.

The target housing and the cartridge, made from Al6061-T6 and Stainless Steel 316L, were analyzed for a maximum allowable design pressure of 21 .5 psi (148.23 kPa) and 14.80 psi (102 .04 kPa) differential respectively which gives an extra 21.7% margin on the design. The normal operating expected pressure for housing and cartridge (100% flow) will be 13.62 psi (93.91 kPa) and 9.63 psi (63.40 kPa) differential respectively. The flow conditions for which a SCRAM is initiated however (115% flow), increases the pressures the housing and cartridge will see to 17.42 psi (120.11 kPa) for the Housing and 12.16 psi (83 .84 kPa) to the cartridge respectively.

Even with an extra 21 .7% margin on the loading, the design still meets the ASME Code allowables in terms of stresses as both, the AL6061 (82 .7 MPa allowed) and SST316L (115 MPa allowed) housing and cartridge components primary stresses fall below the allowables . The design also meets the welding requirements for treatment of the stresses set by Table UW-12 from the ASME code , even with the knockdown factor applied at the welds. Furthermore, as the design has a factor of safety > 2 to yield , US NRC Regulation Guide 2.2 (Reference 6) which states "Materials of construction and fabrication and assembly techniques utilized in experiments should be so specified and used that assurance is provided that no stress failure can occur at stresses twice 53

Attachment 8 ANSYS Target Cartridge , Housing Structura l Analysis Design Calculation Report 30441 ROOO 17IC those anticipated in the manipulation and conduct of the experiment or twice those which would occur as a result of unintended but cred ible changes of, or within , the experiment" is more than satisfied as the design is not close to yield much less failure. These results are summarized in Table 17.

Table 17: Cartridge and Housing Design Limits Design Limits Pressure Factor of Max Pool (differential, Lifetime Safety (US Temperature see Figure 15) NRC Reg 2.2) psi kPa Cycles (Max) Years (Max) Centigrade FOS Target Assembly Housing plus 18 124.1 N/A N/A N/A N/A Cartridge Housing 21.5 148.2 1040 10 so0 8.90 Cartridge 14.80 102.04 104 1 50° 2.88 The stresses for the cladding and pellet interaction similarly are found to be low when compared to the allowed. Stresses and strains as a resu lt of pellet-clad interaction are highest for the [ E a, ] b minima l cold gap (- ). The results show that for the above operating/design conditions f the primary pressure induced stress is< 5 MPa, and well within the primary stress limit of Zircaloy-4 of 6237 psi (430 MPa), at temperature (Figure 30). Secondary stresses as a result of thermal differential expansion and re-location of the cracked pellet where identified as the main drivers for longevity of the cladding . A yield strain for Zircaloy-4 at temperature of about 0.5% is well within the strain range of twice of yield, 1.6%. This therefore meets the secondary stress intensity limit.

With respect to cyclic fatigue for Zirca loy-4 , Figure 31 [ASTM STP 1245 (Reference 15)], which includes irradiated specimens, shows that the maximum quantity of cycles that the cladding can ~

sustain is 20 ,000. With on ly I expected cycles, the cladding has ample design margin. With a ~

factor of safety of > 90 on primary stresses, and an expected lifetime of I cycles out of 20000 cycles limit on the secondary stresses, the design meets ASME B&PV Code as well as Regulatory Guide 2.2.

The performance of the diffuser as a means to extract the cartridge was also analyzed and found to be more than capable of lifting the weight load of a fully loaded cartridge (BON Weight). The maximum pull out force of 850 Newtons was also conservatively calculated based on the maximum Von Mises stresses under this load .

54

Attachment 8 ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17/C Based on the results of the analysis presented in this report, the maximum differential pressure for the Target Assembly shall not exceed 18.0 psi [124 .1 kPa] at the inlet of the Target Assembly under any operating conditions , so as not to exceed the cartridge pressure of 14.80 psi , which is the limiting component pressure.

9 REFERENCES

1. ASME Boiler and Pressure Vessel Code Section VIII, Division 1, 2015.

2. ASME Boiler and Pressure Vessel Code Section VIII, Division 2, 2015.

3. ASME Boiler and Pressure Vessel Code Section II , Parts A Thru D, Material Specifications, 2015.

4. ASME Boiler and Pressure Vessel Code Section IX, 2015.

5. ASME Boiler and Pressure Vessel Code Section V, 2015.

6. Regulatory Guide 2.2, Development of Technical Specifications for Experiments in Research Reactors , U.S . Atomic Energy Commission , November 1973, under mechanical stress effects (C .1.c(3)) .

7. Farmer M. T., Hoffman E. A. , Pfeiffer P. F., Therios I. U. , Wei T. Y. C. "ANL-GenlV-070 -

Generation IV Nuclear Energy System Initiative Pin Core Subassembly Design", 2006.

8. Dohm , Christopher email "Corrosion Samples Monthly Update" sent on Sept. 20, 2016 to Katherine Murray, Junaid Razvi, Chad Carnavale & Hoai Dovan. (APPENDIX A).

9. Zircalloy-4 material properties retrieved from MATWEB from http://www.matweb .com/search/DataSheet.aspx?MatG UID=e36a9590eb5945de94d89a 35097b 7faa&ckck= 1

10. ASME Boiler and Pressure Vessel Code Section 111, Division 1.

11. ASME. VIII, Division 2 Alternative Rules, Rules for Construction of Pressure Vessels . New York: ASME , 2004

12. Fatigue Design Curves for 6061 -T6 Aluminum", G.T. Yahr, Engineering Technology Division Oak Ridge National Laboratory, 1993.

13. Geelhood , K. J., et al. , "FRAPCON-4-0: A Computer Code for the Calculation of Steady-State, Thermal-Mechanical Behavior of Oxide Fuel Rods for High Burnup ," PNNL-19418, Vol. 1, Rev . 2, September 2015.

14. Geelhood , K. J., et al. , "FRAPCON-4-0: Integral Assessment," PNNL-19418, Vol. 2, Rev.

2, September 2015.

15. Garde A.M ., Bradley E.R., ASTM STP 1245 "Zirconium in the Nuclear Industry: Tenth International Symposium: 1994.

55

Attachment 8 ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17IC

16. NUREG/CR-6815, Review of the Margins for ASME Code Fatigue Design Curve- Effects of surface Roughness and Material Variability, Argonne National Laboratory, September 2003 .

17. Roark, Raymond J., Formulas For Stress and Strain, fourth edition , McGraw-Hill Book Company, New York, 1965.ASME. 11 , Part A Ferrous Material Specifications (Beg inning to SA-450), Materials. New York: ASME , 2011a Addenda .

56

ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17 IC APPENDIX A - CHRIS DOHM EMAIL AND SELECTED REPRESENTATIVE IMAGES Chris Dohm Email and Selected Representative Images Dovan, Hoai From: Dohm, Christopher C. <dohmc@missouri .edu>

Sent Tuesday, Se ptember 20, 2016 9:25 AM To: Carnevale, Chad Cc: Dovan, Hoai; Razvi, Junaid; Murray, Ka therine

Subject:

• EXT

• FW: GA Corrosion Samples Monthly Update Attachments: Sl* A (l)JPG; Sl*A (2)JPG; S3*A (l)JPG; S3* A (2)J PG; S4

• A Back side (l)JPG; S4 *A Back side (2).JPG; S4*A Background and S2* A Foreground (l).JPG; S4* A Background and S2* A Foreground (2)J PG; S4* A Front SideJPG; B Sample Rig .JPG; Sl* B (l)JPG; Sl* B (2)JPG; S2* B Foreground and S4

• 8 Other side background (l)JPG; S2

• B Foreground and S4

• 8 Other side background (2)JPG; S2

• B Foreground and S4 B Other side background (3).JPG; S3 B (l)JPG; S3* B (2).JPG; S3* B (3)JPG; S4* B (l)JPG; S4* B (2).JPG; S4-B.J PG; Sl* C (l)JPG; Sl* C (2).JPG; Sl* C (3)JPG; Sl*C (4)J PG; S2*C Foreground and

$3-C BackgroundJ PG; S2* C Foreground and S4 -C Other side Background (l)JPG; S2* C Foreground and S4

• C Other side Background (2).JPG; S2* C Foreground and S4* C Other side Background (3)JPG; S2-C Foreground and S4 C Other side Background (4).JPG; 52-C Foreground and S4-C Other side Background (S)JPG; S4* C (l)JPG; S4-C (2).JPG; S4-C (3).JPG Hi Chad, Forwarding the attached images per Les' request below ....

Chris From: foyto, Leslie P.

Sent: Tuesday, September 20, 2016 11:18 AM To: Dohm, Christopher C.

~Brooks, Kenneth W.

Subject:

GA Corrosion Samples Monthly Update Chris, Please send to GA.

Thanks, Les Chad, We pulled the GA Corrosion Samples on Monday, September 19"', and documented their cond ition with the attached pictures (time stamp is wrong). Please let me know if you have any questions.

Note: The dark to blackish color is definitely an oxide layer. We did not wipe off with a rag.

Thanks, Les A-1

ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017IC A-2

r------

ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441 ROOO 17JC APPENDIX B-TARGET ROD BOWING DUE TO THERMAL AND IRRADIATION EFFECTS FOR SGE EXPERIMENTAL FACILITY Material Properties Material properties for U02 (pellet stack) and Zircaloy-4 (cladding and end caps) were taken from the IAEA's Thermophysical properties database of materials for light water reactors and heavy water reactors [1] . Aluminum 6061-T6 properties (bottom support grid) were taken from the AMSE pressure vessel code [2] .

Thermal Model The thermal model of the single target model rod included the cladding tube with both end caps, a holder at the bottom end cap to approximate the bottom support grid, and a solid internal cylinder representing the U02 pellet stack. To incorporate the non-uniformity of the heat generation , this pellet stack cylinder was split into equal front and back portions . The model also utilized a symmetry plane through the axis of the target rod and perpendicular to the target stack split to reduce computation time . The model is illustrated in Figure 36 .

Cladding Tube Pellet Stack Front Half Bottom End Pellet Stack Cap Rear Half Bottom Support Grid Hold*r - - - - - - Symmetry Plane Figure 36. 30 geometry for target rod bowing analysis.

Data for the front-to-back power skew was taken from GA's MCNP model of the RB-MSS in the MURR pool [30441 R00031]. The ratio of the power density between the front and back of the U02 pellet stack was captured for each rod at 50 axial nodes. The data for this power skew displayed as a scatter plot in Figure 37 . Rods 1 through 11 and Rods 12-22 come from the two separate RB-MSS assemblies. The plot shows that there is considerable variation in the power B-1

ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17/C skew, both from rod to rod and within each rod itself. Rod 9, which had the highest average skew of all rods, was highlight to show this variation.

1.18

• Rod 1

• Rod 2 1.16

• *

• Rod 3 1.14 * * * *

• Rod 4 i ** **

• Rod 5 15 1.12

• Rod 6 l1l

..c 1.10 .;;;

• Rod 7 C'" 1.08

• Rod

~Rod9 8

~ 1.06

• Rod 10 0

-= 1.04

• Rod 11

• Rod 12 C'" 1.02

• Rod 13

• *e Rod 14 1.00

• *** *** e Rod Rod 15 16 0.98 I *

• e Rod 17 0.96

• Rod 18

-30 -20 -10 0 10 20 30 e Rod 19 e Rod 20 Axial Position Relative to Core Centerline (cm) e Rod 21

• Rod 22 Figure 37. Ratio of power density between front and back of U02 pellets throughout GA RB-MSS In addition to the power density in the pellet stack, three boundary further boundary conditions were required: the gap conductance between the pellet stack and the cladding tube, the external convection to the coolant, and the power densities of each section of the pellet stack. The pellet-cladding gap conductance was set to 21.5 kW/(m 2* 0 C), based on previous analysis showing a hot gap width of 10.3 µm and an operating pressure of 1.7 bar [30441 R00021].

The external convection conditions are described in Table 18: Convection Conditions for External Tube . The heat transfer coefficient was calculated using the single-phase Gnielinski correlation

[3] for conservatism (boiling would enhance the heat transfer coefficient and reduce the wall temperature) . The coolant bulk temperature was assumed to vary linearly from 29°C at the bottom of the cladding to 39°C at the top. Coolant properties were taken at the mean temperature of 34°C.

B-2

ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441ROOO17 IC Table 18: Convection Conditions for External Tube Coolant velocity, m/s 5.0 Density, kg/m 3 994.4 Coolant viscosity, Pa*s 0.000743 Coolant thermal conductivity, W/m*K 0.621 Cartridqe hydramulic diameter, mm 10.0 Reynolds number 67,030 Prandtl nummber 4.99 Friction factor 0.0202 Nusselt number 374.5 Heat transfer coefficient, W/(m 2*° C) 23,270 The power density distribution was analyzed for two cases. In the average case, the power density of the front half of the pellet stack is assumed to be 6% greater than the rear half. In the worst case , the power density of the front half is assumed to be 16% greater than the rear half.

This worst case assumption is extremely conservative, as only a few points throughout both targets come close to this power skew, and the average skew for rods containing those points is much lower. For additional conservatism , for both cases the entire stack was assumed to have the maximum power density of 57.25 kW/m , or 2,916 W/cm 3 . The front-rear breakdown for both cases is given in Table 19: Power Density Variation in Pellet Stack for Average and Worst Case.

Table 19: Power Density Variation in Pellet Stack for Average and Worst Case Avera e distribution Worst case distribution Front half 3,001 3,132 Rear half 2,831 2,700 Results - Thermal Figure 38 shows the radial temperature profile of the target rod across the axial midpoint for the rod with the worst case power skew. The power distribution is tilted toward the negative radial position . As the graph shows, this does move the peak temperature slightly away from pellet centerline, but only by about 0.17 mm. The tilt in the temperature profile causes a temperature difference in the cladding from front to back. Based on radial averages of the cladding temperature at the front and the back, the temperature difference between these two locations is about 16.8°C. The average temperature change from the cold condition is 190-210°C.

B-3

ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17 IC 2500 u 2000

-~

0 1500

+-'

~

~ 1000 E

~ 500 0

-3.5 -2.5 -1.5 -0.5 0.5 1.5 2.5 3.5 Radial position (mm)

Figure 38. Radial temperature profile of target rod for worst case power skew Structural Model The structural model uses the same 3D geometry as the thermal model , except that the pellet stack has been removed. As the pellets were only necessary to generate the correct cladding temperature distribution, and do not provide any structural support to the cladding rod, this has no effect on the structural simulation.

The structural model requires three boundary conditions: a fixed support on the top end cap, the imported temperature profile from the thermal simulation, and a contact condition for the bottom end cap and the bottom support grid holder. The outer surface of the extended diameter portion of the top end cap can be treated as fixed because it is effectively constrained by the upper support grid . The imported temperature profile generates the precise thermal strain field that causes the bowing due to the front-to-back power skew.

The final condition, the contact setting between the bottom end cap and the bottom support grid holder, is required because there is a small radial gap of about 0.1 mm between the two components. The contact condition allows the end cap to deflect until it hits the inner surface of the support grid holder, at which point it becomes constrained . This contact was considered frictionless, as most contact force should be in the normal direction.

B-4

ANSYS Target Cartridge , Housing Structural Analysis Design Calculation Report 30441ROOO17 /C Adjustment for Irradiation An initial analysis was performed of the thermal effects on cladding growth , using the worst case front-to-back power density skew. The resulting deformation showed an axial growth of the cladding rod of approximately 0.65 mm. This resu lt is shown in Figure 39, where the black outline shows the undeformed position of the bottom end cap of the target rod . Output from FRAPCON analysis [30441 R00032] showed that the irradiation growth of the cladding rod was 0.56 mm.

Therefore, it was deemed that the effects of the irradiation induced growth could be captured conservatively by in the model by using doubling the Zircaloy-4 coefficient of thermal expansion in the structural model. This is a reasonable assumption because the irradiation strains are induced by fast neutrons, which come primarily from the U02 pellets contained in the target rods (neutrons from the MURR core are well thermalized by the time they reach the target) . Therefore, the front-to-back asymmetry of neutron flux in the cladding rod should follow the asymmetry in the temperature distribution .

o.o11oo--C:==:'.J5.00iilo- - - ===::'.JLO.OOO (mm) 1.500 J.500 Figure 39. Thermal deformation in axial direction of RB-MSS target rod end cap B-5 L

ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 R00017/C Results - Structural The structural simulations were run for both average and worst-case power skews. The results show that the temperature differential between the front and back of the cladding causes the bottom of the cladding rod to deflect away from the MURR core until the bottom end cap hits the back face of the inside of the bottom support grid. This deflection can be seen above in Figure 39.

The contact between the end cap and the bottom support grid causes the middle of the target rod to deflect forward . It is the forward deflection near the axial center of the rod where displacement is highest. The results for the deflection are given in Table 20.

Table 20: Power Density Variation in Pellet Stack for Average and Worst Case Case Maximum Horizontal Deflection , mm Averaqe front-to-back power skew 0.060 Worst-case front-to-back power skew 0.607 Figure 40 provides a visual depiction of deflection of the target rod for the very conservative worst-case power skew. The figure shows the black wireframe of the un-deformed geometry, with the deformed body colored according to the deflection . The left portion of the figure shows a 1: 1 scale of the deflection at its worst point, which shows the maximum deflection of 0.61 mm as slightly greater than the thickness of the cladding (0 .5 mm). The right portion of the figure shows the overall deflection of the target rod by magnifying the displacement by a factor of 30. This greatly exaggerated bowing makes it easier to visualize how the power skew causes the target rod to deform.

B-6

ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOD 17JC True scale deflection 30x magnified deflection Core direction Figure 40. Deflection due to rod bowing for worst-case front-to-back power skew Conclusion The results of the combined thermal-structural analysis show that bowing of the rod due to directional skew of the power distribution within the U02 pellets is not a concern . Analysis predicts that in a worst-case scenario, the maximum horizontal deflection would be about 0.607 mm.

Given the distance between the rod and the cartridge wall when centered is about 4.4 mm, no contact would be expected. Additionally, flow through the cartridge is highly turbulent and boundary layers are very thin, so this level of deflection would not affect the heat transfer

[30441 R00038, 30441 R00033]. It must also be stated that the worst-case scenario is extremely conservative. The more realistic average power skew scenario predicts a deflection of only 60 microns, which would be virtually undetectable. Given these results, it can be concluded that rod bowing due to both thermal and irradiation effects will not affect the performance of the RB-MSS target rods or the system as a whole.

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ANSYS Target Cartridge, Housing Structural Analysis Design Calculation Report 30441 ROOO 17IC References

1. IAEA-TECDOC-1496, Thermophysical properties database of materials for light water reactors and heavy water reactors, International Atomic Energy Agency, June 2006.

2. ASME pressure vessel code - update reference.

3. Rohsenow, W.M., Hartnett, J.P., Cho, Y.1., Handbook of Heat Transfer, 3rd Edition.

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