IAEA Consultancy Meeting Vienna, August 24-27, 2010

Stress AnalysisFinite Element Modeling

DOE – NNSAB&W Y-12, LLCArgonne National LabUniversity of MissouriINR – Pitesti

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Target Manufacturing & Processing

Target Life CycleTarget Life Cycle

Component Specifications

LEU-Foil

Incoming Component Inspections

Target Assembly

Irradiation Rig and Reactor Loading

Coolant

Target Irradiation150 – 200 h

Pool Decay≤ 12 h

Target Transport

Target Disassembly

Target Life Cycle

LEU-Foil Target Development & Qualification

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Project Objectives:� Develop a target qualification methodology that is bounding for all Mo-99 target irradiators� Develop target qualification methodology by building upon the annular target design work and

testing previously performed by ANL and ANSTO/CERCA (circa 2004)� Expand upon ANSTO’s “safety case” document set of analyses� Establish max. target LEU-foil mass ( ≥ 32 g U ) - - - determine if achievable� Develop a “Universal” LEU-foil target qualification document� Develop a ”Universal” target failure analysis methodology (failure in reactor containment)� Provide an alternate target geometry (flat plate, curved plate)� Optimize Safety vs. Economics� Goal is to manufacture a safe, but relatively inexpensive target to offset the inherent economic

disadvantage of using LEU in place of HEU� Develop target material specifications and manufacturing QC test criteria

LEU-Foil Target Development & Manufacturing

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� B&W Y-12’s role:� Manufacturing, testing & quality control� Independent verification of analyses performed by

MU� Construction of flow circuit and test section� U-foil manufacturing experience� New rolling mill procured� Electron beam (EB) welding capability� MU’s College of Engineering’s role:� Thermal hydraulic analyses & structural analyses� Evaluate annular & plate target geometries � Evaluate LEU-foil types (KAERI & Y-12)� Collaboration with Pitesti [ test coupon irradiation

/post irradiation examination (PIE) ]

Rolling MillFactory Acceptance Testing

Target Structural AnalysesTalking Points

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� Analysis of annular target’s structural integrity� Analysis to be validated by testing in flow loop:� Model for conditions experienced during irradiation:� thermal, fission gas pressure, and macroscopic U-swelling

Stress AnalysisFinite Element Modeling

Colors represent the Von Mises stress in the target from interfacial heating.

Ni-Cr Heater Element

Thermocouple Wires Power ≈ 5 kW (max.)Commercial TargetsTarget Power > 30 kW

Target Structural AnalysesNumeric Simulations

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Talking Points� Analysis of plate target’s structural

integrity� Analysis to be validated by testing

in flow loopPlate 1

This is the plate target with a interfacial heat source in between the plates. The edges in this model are fully constrained meaning they cannot move in any direction. This forces the center of the target to pillow out. The colors represent the Von Mises Stress in the target.

Plate 1

Plate 2This is the plate target with a interfacial heat source in between the plates. The edges in this model are not constrained. The areas with highest Von Mises Stress occur around the edges of the plate.

≈ 140 µm deflection

Plate 2≈ 10 µm

LEU-Foil Target Development & Testing

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Laser Displacement Measurement Test

Section

Electroplating Ni FissionRecoil Barrier to U-foil

≈ 9 µm Nickel on Stainless Steel, 1000x

Validation of Numeric Simulations

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Laser Displacement Measurement

Laser Head

Mock Target

Thermal Contact Resistance Analysis

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15

25

35

45

55

65

75

85

95

0 4 8 12 16 20 24 28 32 36 40

LEU Temperature (K)

Heat

Flux (

W/cm

2 )

Air Gap (µm)

1670-1770

1570-1670

1470-1570

1370-1470

1270-1370

1170-1270

1070-1170

970-1070

870-970

770-870

670-770

570-670

470-570

370-470

Clad

ding

Air G

ap

Coola

nt

Heat

Flux f

rom

LEU-

foil

350 ºC / 623 ºK550 ºC / 820 ºK

Example: 95 W/cm2

≈ 9 µm

Melting PointU ≈ 1400 °KNi ≈ 1730 °KAl ≈ 930 °K

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LEU-Foil Target Development & Testing

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Thickness Variation of KAERI U-Foil Samples

Thickness Variation – 50 µmOther studies suggest up to 100 µm

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LEU-Foil Target Development & Testing

Side view of the thickness gage. The green and white tubes are the ‘air-in’ lines to the probe. The probe isbrought down with the help of a foot switch

p1p2

p3p4

p5

0.004

0.00405

0.0041

0.00415

0.0042

0.00425

d1d2

d3d4

d5

0.0042-0.004250.00415-0.00420.0041-0.004150.00405-0.00410.004-0.00405

surface plot of foil1

Analytical Input Data Required� In order to develop a conservatively bounding “Safety Case” document, stakeholders

would need to provide reactor specific irradiation data� For example: � max. thermal neutron flux ( ≤ 2.8E14 n/cm2 -s )� max. irradiation time ( ≤ 200 hrs )� % 235U burnup ( ≤ 8% )� target heat flux limit ( W/cm2 )� Containment “free” volume ( m3 )� Depth (from pool surface ) at which targets are irradiated ( ≥ 7 m, 23 ft )� Target cooling period ( ≤ 12 h )� Current transport cask shielding design: total fission product activity at time of

target transport � grams (or mols) of noble gases ( Kr & Xe ) generated during target irradiation� Ideal target dimensions (i.e., size) and LEU-foil mass� Ideal LEU-foil thickness (125 µm [5 mils] – 180 µm [7 mils] ); specific target

power ( W/gU ) increases with decreasing foil thickness ( ≈ 5% per 25 µm ∆ ) � Preferred target geometry ( annular, plate )

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Target Development & Qualification Philosophy

- - - Food for Thought - - -

�A LEU-Foil target is a Mo-99 production “consumable” with a limited life cycle

�There is no question that it must maintain its structural integrity during irradiation and pool cooling - - - Reactor safety is of first priority

�However, does a Mo-99 production target need to be designed and qualified to the same extent as reactor fuel elements?

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Development of Tubing Mandrel Expansion DevicePrinciple of Operation:Radially expand inner tube into the outer tube

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Hardened Steel

Bearing Surfaces

Radial Expansion

Annular Target Disassembly Device - Prototype

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Next generation prototype will be automated for remote operation