HFIR Irradiation and In-Situ Capabilities

1. HFIR Irradiation and In-Situ Capabilities Joel McDuffee Thermal Hydraulics & Irradiation Engineering Group, Reactor and Nuclear Systems Division

2. Pressurized flux-trap-type reactor; light-water cooled and moderated HEU fuel: U3O8 dispersed in aluminum Two annular fuel elements Center cylindrical flux trap, 12.70 cm diameter Nominally six 25-day cycles per year The High Flux Isotope Reactor

3. High Flux Isotope Reactor (HFIR) Experimental Locations • 28–30 target pins are located in the flux trap (~1.27 cm OD) • 8 RB* positions (~5.07 cm OD) • 16 small VXF sites (~4.02 cm OD) • 6 large VXF sites (~7.2 cm OD)

4. Total number of irradiations drops in FY15 but capsules are larger, consuming more space in the reactor • More full-length capsules than FY14. (29 vs 26 in the target region) • Average planned duration of a capsule irradiations is 20.8 cycles, up from 17.5 in FY14. • Longest planned capsule irradiation is 84 cycles. • Primary programs in FY15 include: • DOE Fusion Energy • Pu-238 research • WFO Graphite irradiations • Additionally, Cf-252 production targets did not arrive when planned. Space in the core had already been emptied in preparation of their arrival.

5. Neutron Flux In HFIR

6. Characteristics of Major Irradiation Facilities in HFIR

7. Materials Research in Rabbits • Nominal Ø11.0 mm x 55.9 mm Tensile Creep Rabbit Capsule Ferritic steel Tensile Specimens at 300°C Ferritic steel bend bars at 300°C

8. Thermal Neutron Shielded Rabbit Design Spring keeps the stack in place Fuel TEM disks are sandwiched between two ZrO2 disks to prevent interaction with the pure Gd metal Gadolinium blocks shield fuel disks from thermal neutrons Visible gap between Gd blocks ensures good thermal contact

9. Compliant Foil for Temperature Control • Embossed foil provides a heat transfer path that accommodates shrinking and swelling

10. Nominal Ø12.7 mm x 508 mm JP26: 300°C to 500 °C, 9.5 dpa JP27300°C to 500 °C, 21 dpa JP28, JP29: 300°C to 500 °C, 85 dpa JP30, JP31: 300°C to 650 °C, 21 dpa Recent Target Capsules

11. Instrumented Experiments Offer Precise Temperature Control • Precise temperature control independent of reactor power • Through internal heatersthat run through thelength of theexperiment • Or by active control of the gas mixture in a gap • Helium • Neon • Argon • Nominal Ø1.5″ x 20″ (Ø38.1 mm × 508 mm) VTX (RB-13J) Experiment (RB-18J) Experiment

12. Materials Irradiation Facility (MIF) HFIR’s STACK Supervisory Control System I/O • Gas effluent system has a radiation monitoring system, and there are two consecutive hold-up tanks which give activated gases time to decay before they are delivered to HFIR’s hot off gas (HOG) system. Gas Supply System TC Gas Effluent System • The raw gas from the bottles is routed though a gas supply cleanup system which removes oxygen and moisture Gas Routing and Control System Helium Argon Neon ZONE A Gas routing system distributes feed gas streams into the experiment based on the irradiation design requirements. ZONE B ZONE C Typical Experiment

13. 15J: 300 °C to 450 °C, 6 dpa 17J: 450 °C to 700 °C, 4.4 dpa Lithium-filled subcapsules can accommodate multiple specimen geometries, and minimize temperature gradients Fusion Experiments MFE-RB-17J and MFE-RB-15J

14. MFE-RB-19J Experiment • Collaboration with international partners PHENIX and JAEA • Essential experiment for tungsten research for PFC, blanket structural materials research • Project will have a large impact on fate of tungsten • Dose: • 1~1.5 dpa, 6 cycles (subject to schedule and change above 1 dpa) • Temperature regions • 250–300 °C (JAEA) • 500 °C (FS/W requirement) • 800 °C (reference data available for no shield) • 1,200 °C (above re-crystallization temp.) • Requires a thermal neutron shield

15. MFE-RB-19J Experiment 500 °C 100 mm 1,200 °C 105 mm JAEA 800 °C 110 mm

16. 500C Zone Layout NT2 QTY 29 6SQ5D QTY 6 D6T2 QTY 10 D6TQ QTY 11 TEM QTY 12 D6T1 QTY 52 D6TH QTY 35 D10T2 QTY 2 D6TH QTY 80 D10T1 QTY 10 D10TH QTY 10 D10TQ QTY 15 SS-J QTY 94 D6TQ QTY 11

17. MFE-RB-19J Experiment • The MFE-RB-19J experiment was installed and began operation for Cycle 465 on June 14

18. New Developments in Irradiation Experiment Capabilities Thermosyphon Facility Pressurizer Thermosyphon • Advanced Radiation Hard Fiber Optic Sensing • Spatially distributed temperature/strain measurements • Resistant to harsh reactor conditions • Thermosyphon Facility • Offers near isothermal operating conditions • Larger experiment heat loads are allowable • Provides independent coolant with sealed containment and no moving parts • Activated Experiment Encapsulation Laboratory (AXEL) • Provides capabilities to encapsulate highly radioactive samples for irradiation in HFIR • Ensures same level of encapsulation quality as a bench top capsule build Pump Heat Exchanger Optical Sensor AXEL workflow Optical Sensor Load Weld Test Distributed fiber optic sensing system for future instrumented irradiation experiments

19. Summary • ORNL uses many types of experiment designs to achieve experiment objectives • Rabbit capsules offer lower cost and quick turnaround • Target capsules offer larger volumes and multiple temperature zones • Instrumented capsules offer larger volumes and temperature control • Lithium specimen bath has been successfully used