Post-Irradiation analysis of fission gases in nuclear fuels

Transcription

1 Post-Irradiation analysis of fission gases in nuclear fuels Ch. VALOT, J. NOIROT, Y. PONTILLON MINOS Workshop, Materials Innovation for Nuclear Optimized Systems December 5-7, 212, CEA INSTN Saclay, France

2 Outline Fission gases in LWR: a safety issue PIE facilities Fission gases behavior: nominal operating conditions Fission gases behavior: simulated accidental conditions Further projects CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 2

3 Fission gas a safety issue in Light Water Reactor Industrial issue Safety criterion : Internal cladding pressure at fuel rods end of life Scientific needs Fission gases Formation/Evolution... - Nano-scale bubbles formation - From nano-scale to micro-scale bubbles - Fission gases features (bubbles internal pressure) Fission gases vs. fuel microstructure - Link between fission gas release and fuel µstructure - Fission gases involved in the HBS (High Burnup Structure) formation - Gas release from HBS (normal and off-normal conditions) [1] [1]: B. Petitprez, B. Delaye, S. Beguin Proceedings of EHPGM Enlarged Halden Project Group Meeting, Lillehammer, 25 [2]: Ch. Valot, J. Noirot, Y. Pontillon Séminaire MINOS, Septembre 211, Saclay, Neurospin CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 3 [2]

4 Outline Fission gases in LWR: a safety issue PIE facilities Fission gases behavior: nominal operating conditions Fission gases behavior: simulated accidental conditions Further projects CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 4

5 Post-Irradiation Analyses: Cadarache LECA-STAR Hot Laboratory STAR LWR puncturing, NDE Annealing test Sample preparation Metallographic examination LECA Microanalyses laboratory CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 5

6 Out of Pile annealing capabilities Experimental objectives: Better understanding of fuel behavior under nominal condition, Out of Pile simulation of fission gas release in case of accidental conditions (LOCA or RIA) Device capabilities: Sampling: 1-2 mm segment High Frequency induction furnace: - Max. Temp.: 28 C - Max. Temp. ramp: 2 C/s Accurate temperature monitoring Fission gas analysis: - Gamma spectrometry for online measurement - Gas-chromatography for stable gas analysis (He ) [3]: J. Noirot, Ch. Gonnier, L. Desgranges, Y. Pontillon, J. Lamontagne IAEA-TECDOC-CD [4]: Y. Pontillon et al. Proc. Of the 24 International Meeting on LWR Fuel Performance, Orlando, Florida, September 1-22, 24 Annealing device principle [3, 4] CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 6

7 Post Irradiation Examination capabilities Actinides and FP: Location Quantification Fuel microstructure: Porosity, HBS Crystalline structure MEB EPMA profilometer - SEM Hot cell SIMS XRD EPMA(CAMECA SX1R) Profilometer (STILL) SEM XL 3 (FEI) - Modified equipments - α-box and gamma shielding SIMS (CAMECA IMS-6F) µxrd (GENERAL ELECTRIC) CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 7

8 Xenon analysis: Coupling SEM, EPMA and SIMS Primary Electrons EPMA Secondary Electrons X rays 1 µm nm Distribution and content: Actinides, Fission Products (Solid, gas) SEM 2 µm 2 µm X-ray Map Xe Xe inventory EPMA quantitative analysis Sample preparation effect (RIM, fuel center) In depth SIMS analysis SIMS to EPMA calibration Primary Ion beam Sample Isotopic analyses Trace elements (ppb) Gas inventory SIMS Before sputtering High Burn-Up fuel 2 µm after sputtering 132 Xe intensity (c/s) Peaks (bubbles full of gas) sputtering time (s) Baseline (~Gas dissolved in the matrix) CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 8

9 Outline Fission gases in LWR: a safety issue PIE facilities Fission gases behavior: nominal operating conditions Fission gases behavior: simulated accidental conditions Further projects CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 9

10 Fission gas behavior: nominal operating conditions 67 GWd/tU high burn-up UO 2 PWR fuel 1,2 1 Fuel rod NDE gamma spectrometry Fuel pellet µanalysis Counts/Max Count,8,6,4,2 Axial burn-up distribution 1,6 Fission product axial distribution Axial position (mm) Free Volume and Gas pressure measurement Fission gas inventory (released from fuel column) FGR F% = FGC ( FissionGas Release) ( FissionGas Creation) 1,8 W%(Nd) CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 1 weight % 1,4 1,2 1,8,6,4,2 A Burn Up Distance/fuel periphery (µm) FG behavior vs. local µstructure Local FGR vs. fuel rod scale FGR BU (GWd/tU)

11 Fission gas: local behavior Fuel periphery SEM: High density of gas bubbles RIM structure EPMA Xe profile: << creation FGR? SIMS depth profile: Xe mainly precipitated Baseline (precipitated in nano bubbles) EPMA total inventory creation No significant FGR Xe (weight%) 2,5 2 1,5 1,5 1,8 Xe creation Xe creation total Xe SIMS,6 r/r,4 Xe EPMA Xe EPMA Baseline Xe SIMS,2 132 Xe depth profile CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France Xe (c/s) Sputtering time (s)

12 Fission gas: local behavior Fuel center SEM: High density of gas bubbles EPMA Xe profile: << creation FGR? SIMS depth profile: Part of Xe precipitated nano-precipitated Xe EPMA total inventory < creation Local FGR Xe (weight%) 2,5 2 1,5 1,5 Xe creation Xe creation total Xe SIMS Xe EPMA Xe EPMA Baseline Xe SIMS 132 Xe (c/s) 132 Xe depth profile ,8,6 r/r,4,2 Sputtering time (s) CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 12

13 Quantitative analysis 2,5 Xe creation total Xe SIMS W%(Xe) "µsonde" Baseline Xe SIMS Local/Total FG release Fuel rod FG release: 6,2% (BU 67 GWd/tU) Local FG release: 8-1% (local BU 73 GWd/tU) Xe (weight%) 2 1,5 1,5 Fission Gas bubble pressure 1,8,6,4,2 r/r RIM.3-,4 r/r Center W% Xe in bubbles S% Bubbles (< 3,5 µm) At. Vol. (Å 3.at -1 ) Bubble pressure (MPa) [4] 13 (3 K) 8 (3 K) 8 (3 K) 84 (65 K) 13 (122 K) 15 (128 K) [4]: C. Ronchi, JNM, 96 (1981) CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 13

14 Outline Fission gases in LWR: a safety issue PIE facilities Fission gases behavior: nominal operating conditions Fission gases behavior: simulated accidental conditions Further projects CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 14

15 Fission gas behavior: simulated accidental conditions 63 GWd/tU high burn-up UO 2 PWR fuel [5] Lost Of Cooling Accident (LOCA) simulation On-line fission gas (85Kr) release Overall release Temperature dependant bursts [5]: M. Marcet et al. Proc. Top Fuel 29 conference, Paris, France, September CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 15

16 Fission gas behavior: simulated accidental conditions RIM Center After annealing test Before annealing test 132 Xe (c/s) 132 Xe (c/s) Sputtering time (s) Sputtering time (s) 132 Xe (c/s) 132 Xe (c/s) Sputtering time (s) Sputtering time (s) RIM cracking No significant evolution of nano-precipitated gas Sharp decrease of Xe bubbles Grain boundaries opening no significant evolution of nano-precipitated gas No SIMS bubble detection CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 16

17 Fission gas behavior: simulated accidental conditions 2,5 before annealing test after annealing test 2 Xe (weight %) 1,5 1,5 1,8,6,4,2 r/r Annealing treatment (on-line FG release) PIE After heat treatment 11.5% ( 85 Kr) 12% ( 132 Xe) 5% RIM 35% center 15% mid-radius CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 17

18 Summary Nominal operating conditions Multi-scale (Rod to pellet) FG analyses Fuel behavior understanding New fuel qualification Safety of nuclear fuel Simulated accidental conditions Importance of coupling separate effect experiments with quantitative PIE FGR vs. microstructure mainly in hot part of the pellet HBS gas retention capacities Overpressure of FG FGR modeling FGR features: mainly from grain boundaries HBS and center release bubbles interconnections Critical temperature identified CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 18

19 Further projects: SEM/FIB/EBSD device High pressure annealing loop FIB column Building gas exhaust EDX detector HIP furnace Cooling loop Ionisation chamber EBSD device Safety tank Hot cell Gas trap Gas sampling 3D extraction of porosities and Grain boundaries network Safety line Compressor Gamma on-line examination Argon bottle Gas storage tank Safety wall µsample preparation TEM analyses Synchrotron analyses (MARS beamline) Impact of fuel rod internal pressure on FGR Max Temperature/pressure: 16 C/16 bars Fission gas behavior: nominal operating conditions Standard fuel sample, one pellet Main analytical capability: online gamma spectrometry CEA-DEN-CAD-DEC-SA3C MINOS Workshop - December 5-7, 212, CEA INSTN Saclay, France 19

20 Thank you for your attention Contribution: I. Aubrun, Ph. Bienvenu, S. Clément, B. Lacroix, J. Lamontagne, B. Petitprez, C. Pozo Th. Blay, E. Brochard, P. Delion, I. Roure PAGE 2 CEA 1 AVRIL DÉCEMBRE 212 Commissariat à l énergie atomique et aux énergies alternatives Centre de Cadarache 1318 Saint Paul Lez Durance T. +33 () F. +33 () Christophe.valot@cea.fr Etablissement public à caractère industriel et commercial RCS Paris B DEN DEC SA3C LEMCI