1. www.inl.gov Thermal Design and Analysis of Capsule Experiments in the ATR Paul Murray ATR Experiment Design and Analysis Idaho National Laboratory NSUF User Meeting June 22, 2015 Temperature Indications and Comparison to Simulation

2. Contents Introduction – static and active temperature control EPRI static capsule experiment – Experiment design – Temperature indicators (melt wires and SiC) – Reactor power history – Melt wire temperature indications – SiC temperature indications – Heat transfer simulations – Irradiation temperature estimates UCSB lead-out capsule experiment – Experiment design – Heat transfer simulations – Temperature measurements 2

3. ATR core cross-section EPRI experiment UCSB experiment

4. Capsule experiments A gas gap of known thermal resistance is used to attain the desired specimen temperature Gas gap temperature controlled capsule experiments – Static capsule experiment with fixed temperature control gas – Lead-out experiment with variable temperature control gas Pressure tube Helium/argon/neon gas gap Specimens Specimen holder Reactor coolant 50°C, 360 psig

5. EPRI static capsule experiment Capsule containing zirconium alloy specimens is irradiated in the A-16 position in the ATR northwest lobe Experiment is designed to study irradiation induced growth of zirconium alloys 5

6. Experiment design 50 specimens (10 stacks of 5) are contained in a helium-filled pressure-retaining stainless steel capsule Gas gap temperature control is designed to maintain specimen temperature at 285ºC ±10ºC 6 Spacer Specimens Holder Capsule

7. 7 Temperature indicators Six melt wires (labelled A – E) and two SiC rods (labelled F) located in dowel holes at top and bottom of specimen holder Melt wire label Location of melt wire in specimen holder Composition of melt wire Melting temperature ATop Right100% Sn231.8°C DTop Right80% Au 20% Sn279.5°C CTop Left90% Pb 10% Sb252.4°C BBottom Right95% Sn 5% Sb238.6°C EBottom Right90% Pb 5% Ag 5% Sn302.9°C CBottom Left90% Pb 10% Sb252.4°C F C C F B E D A Top Bottom Dowel holes Capsule Holder Specimens

8. Temperature indicators Melt wires are encapsulated in helium-filled quartz tubes; post- irradiation visual inspection is used to determine if melting occurred Measured change in SiC electrical resistance resulting from post- irradiation annealing is used to estimate irradiation temperature 8 Interior of annealing furnace Apparatus for resistance measurement SiC

9. 9 Reactor power history Cycle Average Lobe Power (MW) EFPD 149A 18.0 37 149B 18.0 54 150B 18.0 42 151A 18.9 60 151B 18.9 56 152B 18.9 52 SiC indicates temperature corresponding to average power during the final irradiation cycle Melt wire indicates temperature corresponding to peak power during the irradiation

10. 10 Reactor power history Peak lobe power 19.44 MW occurred during cycle 152B on 12/06/2012

11. 11 Melt wire temperature indications All melt wires at top of holder showed clear indications of melting Peak irradiation temperature at top of the holder is equal to or greater than 279.5°C (melting temperature of 80 Au 20 Sn) Composition of melt wire Melting temperature Melted during irradiation 100% Sn231.8°CYes 80% Au 20% Sn279.5°CYes 90% Pb 10% Sb252.4°CYes 95% Sn 5% Sb238.6°CYes 90% Pb 5% Ag 5% Sn302.9°CNo 90% Pb 10% Sb252.4°CYes Sn 80Au 20Sn

12. 12 Melt wire temperature indications One melt wire (90 Pb 5 Ag 5 Sn) at bottom of holder did not melt; other wires showed clear indications of melting Peak irradiation temperature at bottom of holder is less than 302.9°C (melting temperature of 90 Pb 5 Ag 5 Sn) Composition of melt wire Melting temperature Melted during irradiation 100% Sn231.8°CYes 80% Au 20% Sn279.5°CYes 90% Pb 10% Sb252.4°CYes 95% Sn 5% Sb238.6°CYes 90% Pb 5% Ag 5% Sn302.9°CNo 90% Pb 10% Sb252.4°CYes 90Pb 5Ag 5Sn95Sn 5Sb

13. 13 SiC temperature indications Indicated irradiation temperature at top of holder is 258°C ±10°C

14. 14 SiC temperature indications Indicated irradiation temperature at bottom of holder is 279°C ±10°C

15. Heat transfer simulation at 18.9 MW 15

16. Heat transfer simulation at 19.4 MW 16

17. Temperature indications and results of simulation 17 Reactor Lobe Power Indicated Irradiation Temperature of SiC Indicated Irradiation Temperature of Melt Wires Calculated Irradiation Temperature of SiC Calculated Irradiation Temperature of Melt Wires Calculated Irradiation Temperature of Specimens 18.0 MW275°C - 291°C 18.9 MW 258°C ± 10°C (top) 279°C ± 10°C (bottom) 261°C - 269°C (top) 266°C - 271°C (bottom) 284°C - 301°C 19.4 MW > 279.5°C (top) < 302.9°C (bottom) 277°C (top) 279°C (bottom) 290°C - 307°C

18. Irradiation temperature estimates 18 Cycle Average Lobe Power (MW) Estimated Irradiation Temperature 149A 18.0 275°C - 291°C 149B 18.0 275°C - 291°C 150B 18.0 275°C - 291°C 151A 18.9 284°C - 301°C 151B 18.9 284°C - 301°C 152B 18.9 284°C - 301°C

19. UCSB lead-out capsule experiment Capsule containing low alloy carbon steel specimens is irradiated in the I-22 position in the ATR southeast lobe Capsule is instrumented with 28 thermocouples Active gas gap temperature control using helium-argon control gas is designed to maintain specimen temperature at 250°C to 310°C

20. Experiment design Numerous multi-purpose disc specimens, compact tension specimens, and tensile specimens contained in a thin-walled sleeve Thermocouples and gas lines located in a sealing tube assembly that contains the specimen packets Helium-argon control gas mixture is adjusted based on temperature feedback from thermocouples Gas lines and TCs Sealing tube assembly Specimens Sleeve

21. Experiment design Specimens arranged in packets according to desired irradiation temperature Three gas zones with variable gas gaps Selected thermocouples in each zone used for temperature control Bottom zoneTop zoneMiddle zone

22. Heat transfer simulation Simulation using a 50% He – 50% Ar control gas mixture used to establish thermocouple setpoints at approximately 276°C Control TCs

23. Heat transfer simulation Simulation using actual control gas mixture on 6/20/2011 (bottom zone 42% He, middle zone 62% He, top zone 48% He)

24. Temperature measurements Simulation using actual control gas mixture during irradiation

25. Temperature measurements Error bars correspond to ±0.002 inch uncertainty in gas gaps

26. Summary EPRI static capsule experiment – Passive temperature indication UCSB lead-out experiment – Active temperature indication Comparison of temperature indications to heat transfer simulations – Temperature uncertainty is approximately ±30°C for a materials irradiation at 300°C