DOE NNSA B&W Y-12, LLC Argonne National Lab University of Missouri INR Pitesti. IAEA Consultancy Meeting Vienna, August 24-27, 2010

Transcription

1 Stress Analysis Finite Element Modeling DOE NNSA B&W Y-12, LLC Argonne National Lab University of Missouri INR Pitesti IAEA Consultancy Meeting Vienna, August 24-27, 2010

2 Target Manufacturing & Processing Coolant Component Specifications Target Assembly Target Irradiation h Target Transport LEU-Foil Incoming Component Inspections Irradiation Rig and Reactor Loading Pool Decay 12 h Target Life Cycle Target Life Cycle Target Disassembly 2

3 LEU-Foil Target Development & Qualification 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 3

4 LEU-Foil Target Development & Manufacturing 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 Rolling Mill Factory Acceptance Testing Evaluate LEU-foil types (KAERI & Y-12) Collaboration with Pitesti [ test coupon irradiation / post irradiation examination (PIE) ] 4

5 Target Structural Analyses Stress Analysis Finite Element Modeling Talking Points 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 Colors represent the Von Mises stress in the target from interfacial heating. Thermocouple Wires Power 5 kw (max.) Commercial Targets Target Power > 30 kw Ni-Cr Heater Element 5

6 Plate 1 Plate 2 Target Structural Analyses Numeric Simulations 140 µm deflection 10 µm Talking Points Analysis of plate target s structural integrity Analysis to be validated by testing in flow loop Plate 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 2 This 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. 6

7 LEU-Foil Target Development & Testing Electroplating Ni Fission Recoil Barrier to U-foil Laser Displacement Measurement Test Section 9 µm Nickel on Stainless Steel, 1000x 7

8 Validation of Numeric Simulations Laser Displacement Measurement Mock Target Laser Head 8

9 Thermal Contact Resistance Analysis 550 ºC / 820 ºK 350 ºC / 623 ºK 9 µ m Example: 95 W/cm Air Gap (µm) Melting Point U 1400 K Ni 1730 K Al 930 K Heat Flux (W/cm 2 ) Coolant Cladding Air Gap LEU Temperature (K) Heat Flux from LEU-foil

10 LEU-Foil Target Development & Testing Thickness Variation of KAERI U-Foil Samples Thickness Variation 50 µm Other studies suggest up to 100 µm 10

11 LEU-Foil Target Development & Testing surface plotof foil Side view of the thickness gage. The green and white tubes are the air-in lines to the probe. The probe is brought down with the help of a foot switch d1 d2 d3 d4 d5 p1 p2 p3 p4 p5 11

12 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/cm 2 -s ) max. irradiation time ( 200 hrs ) % 235 U burnup ( 8% ) target heat flux limit ( W/cm 2 ) Containment free volume ( m 3 ) 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 ) 12

13 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? 13

14 Development of Tubing Mandrel Expansion Device Principle of Operation: Radially expand inner tube into the outer tube Bearing Surfaces Hardened Steel Radial Expansion 14

15 Annular Target Disassembly Device - Prototype Next generation prototype will be automated for remote operation 15