Understanding of corrosion mechanisms after irradiation : effect of ion irradiation of the oxide layer on the corrosion rate of M5 alloy M. Tupin, R. Verlet, S. Miro, G. Baldacchino, M. Jublot, K. Colas Section for Research of Irradiated Materials CEA Université Paris Saclay K. Wolski Ecole des Mines de St Etienne A. Ambard, M. Blat, I. Idarraga EDF D. Kaczorowski AREVA M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
utline Issue Background and objectives Experiment approach and techniques Results Description of the modelling Conclusions and perspective M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
Issue Comparison of M5 and Zircaloy-4 performance in PWR [Garner, ANS LWR (7)] Reaction of oxidation : Zr + H Zr + H Zircaloy-4 : «High Burn-Up» acceleration M5 : no kinetic acceleration beyond 35 GWd/tU Why a such good corrosion resistance in PWR conditions for M5 alloy? M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
Background and objectives Irradiation impact on the microstructure of the claddings and on the oxidation kinetics Effect on the metallurgical state of the alloy Impact on the oxide microstructure and oxide properties Influence on the chemistry of the water : radiolysis M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 4
Background and objectives Ion irradiation different distribution of defects. Uniform concentration of irradiation defects in the oxide simulate the neutron irradiation effect. High local content of defects : metal/oxide interface information of the corrosion mechanism Conclusions of the last ASTM [Tupin, ASTM (4)] Zy4 : increase of the oxygen diffusion flux M5 : decrease of the oxygen diffusion flux M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 5
Background and objectives Ion irradiation different distribution of defects. Uniform concentration of irradiation defects in the oxide simulate the neutron irradiation effect. High local content of defects : metal/oxide interface information of the corrosion mechanism bjectives : Quantify the effect of irradiation defect on the oxidation rate of M5. Isotopic exposure and SIMS analyses of profiles. Kinetic study from the weight gain Irradiation defect stability during long term exposure in simulated PWR conditions M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 6
Experimental Approach I(cps/s) - Mirror-polished samples - days at 36 C,.7 MPa in H 6 with Li, B. - H / D 6 mix solution (/8%) - 4 h at 36 C,.7 MPa - Li, B. Pre-oxidation SRIM Simulation Irradiation Characterization isotopic exposure + SIMS analyses Ion and energy choice JANNUS rsay (Fr) CSNSM V ox a J - Defect distribution 6 4 5 4.5 µm - Defect content (dpa, Se) 4 4 3 4 4 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 4 7..4.6.8 X (µm)
Chemical composition of the M5 samples Experimental Approach Material Alloying elements Fe (%) Cr (%) Sn (%) Nb (%) (%) H, ppm Zr M5.35.5 -.3.3 4 Bal uniform concentration of irradiation defects in the oxide irradiation experiments? M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 8
[V o ] (nm -3 ) Irradiation experiments : He +.3 MeV Experimental Approach 6 Irradiation experiments 5 4 3 Ion type Energy (MeV) Fluence (cm - ²) Flux (cm - ².s - ) Temp. ( C),5,5 Average Sn (ev/nm/ion) Average Se (ev/nm/ion) oxide depth (µm) Dose (dpa) irradiation experiments performed on JANNUS rsay facilities He +.3 6 5 x 6.6 585.36 He +.3 7 5 x 6.6 585.36 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 9
Experimental Approach Characterization technique I(cps/s) - Mirror-polished sample - days at 36 C,.7 MPa in H 6 with Li, B. - H / D 6 mix solution (/8%) - 4 h at 36 C,.7 MPa - Li, B. Pre-oxidation SRIM Simulation Irradiation? Characterization isotopic exposure + SIMS analyses Ion and energy choice JANNUS rsay (Fr) CSNSM V ox a J - Defect distribution 6 4 5 4.5 µm - Defect contents (dpa, Se) 4 4 3 4 4 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 4..4.6.8 X (µm)
Experimental Approach Characterization technique Irradiation defects studied Electron Paramagnetic Resonance on single crystal of cubic zirconia Find a technique able to detect the irradiation defects? Raman Spectroscopy Vibration modes of the lattice M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
Experimental Approach Characterization technique Irradiation defects studied Electron Paramagnetic Resonance on single crystal of cubic zirconia Find a technique able to detect the irradiation defects? Raman Spectroscopy Vibration modes of the lattice 76 8 tetragonal phase monoclinic Quadratic phase Monoclinic phase phase 475 635 333 6 49 65 38 5 535 558 647 unirradiated material M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
Intensity (a. u.) Experimental Approach Characterization technique Spectroscopy Raman after irradiation : detection of defects? 65 7 7 ions/cm² (~ 3% q-zr ) 6 ions/cm² (~ 3% q-zr ) unirradiated (~ 3% q-zr ) Raman Shift cm - - New vibration band at 7 cm - signature of irradiation defects Raman Spectroscopy : good tool to detect irradiation defects M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
Results Raman Spectroscopy and SIMS analyses I(cps/s) - Mirror-polished sample - days at 36 C,.7 MPa in H 6 with Li, B. - H / D 6 mix solution (/8%) - 4 h at 36 C,.7 MPa - Li, B. Pre-oxidation SRIM Simulation Irradiation RAMAN Spectroscopy Characterization isotopic exposure + SIMS analyses Ion and energy choice JANNUS rsay (Fr) CSNSM V ox a J - Defect distribution 6 4 5 4.5 µm - Defect contents (dpa, Se) 4 4 3 4 4 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 4 4..4.6.8 X (µm)
primary water Results Raman Spectroscopy and SIMS analyses Zr 6 Zr 6 H 6 6 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 5
Milieu primaire Results Raman Spectroscopy and SIMS analyses Zr 6 Zr 6 6 H 6 6 6 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 6
Intensity (cps/s) I (c/s) surface metal/oxide interface., 6 surface concentration 7. 6 Cs- 8 6 6 6 4 6 6 6 x I Results Raman Spectroscopy and SIMS analyses 5 I I b b 5 I - I I b nat b - I nat atomic fraction I.8 8 5.6 6 5.4 4 5. 5 Q penetration depth, X d,,5,5 X (µm) oxide depth (µm),,,3,4,5,6 oxide depth X (µm) (µm) J X d t Q isotopic_exchange D t a D a Average diffusion flux ratio : X d 4t M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry J J NI = x I x I NI dx dx 7
SIMS intentsity (c/s) SIMS profile of after irradiation Results Raman Spectroscopy and SIMS analyses 4 6 7 3 6 J J NI 6 Unirradiated He + 7 cm - ² 6 He + 6 cm - ²,,,3,4,5,6 oxide depth (µm) marked decrease of amount absorbed in the oxide after irradiation M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
SIMS intentsity (c/s) SIMS profile of after irradiation Results Raman Spectroscopy and SIMS analyses 4 6 C s_ (%) outer interface fraction 35 9 3 6 6 6 C s_ ~35 % Unirradiated He + 7 cm - ² He + 6 cm - ² marked decrease of absorbed in the oxide after irradiation,,,3,4,5,6 oxide depth (µm) high reduction of the surface concentration whatever the fluence M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 9
SIMS intentsity (c/s) X Raman Spectroscopy and SIMS analyses SIMS profile of after irradiation : D a? d D t a D Apparent diffusion coefficient D a (cm²/s) 9.6-6 4.9-6 9. -6 a X 4t 4 6 3 6 6 6 marked decrease of absorbed in the oxide after irradiation d : : Unirradiated He + 7 cm - ² He + 6 cm - ²,,,3,4,5,6 oxide depth (µm) Results higher defect concentration higher oxygen diffusion coefficient M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
SIMS intentsity (c/s) : Results Raman Spectroscopy and SIMS analyses SIMS profile of after irradiation : average diffusion flux ratio J J NI = x I x I NI dx dx 4 6 3 6 J 6 J NI. 39 6 6 Unirradiated He + 7 cm - ² He + 6 cm - ² J 7 J NI. 55,,,3,4,5,6 oxide depth (µm) marked decrease of oxygen diffusion flux M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
xide thickness (µm) xide thickness (µm) Kinetic study in autoclave after irradiation 3,5 3,5 Irradiation with.3 MeV He + ion at a fluence of 7 cm - ² unirradiated sample Results Irradiation defect stability and kinetics,5 R irrad /R ref =.56,5,5,5 irradiated sample 4 6 8 4 t (d) 3 4 5 t (d) R irrad R ref J 7 J NI marked decrease of oxidation rate after irradiation (consistent with SIMS) long term effect of irradiation M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry
xide thickness (µm) Kinetic study in autoclave after irradiation 3,5 3,5 Irradiation with.3 MeV He + ion at a fluence of 7 cm - ² unirradiated sample Results Irradiation defect stability and kinetics Follow-up the defects by RAMAN,5 irradiated sample,5 4 6 8 4 t (d) marked decrease of oxidation rate after irradiation (consistent with SIMS) long term effect of irradiation very slow rate of annealing in simulated PWR conditions : presence of the defects up to days M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
Results Characterization balance sheet Modelling required characterizations : XPS : surface analyses Sample niobium surface fraction (%) (/Zr+Nb) Reduction of niobium segregated concentration after irradiation and reoxidation M5 unirradiated in simulated PWR conditions 4.5 M5 irradiated ( 7 cm - ) 4.3 M5 irradiated and 4h reoxidation.8 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 4
Description of the modelling Hypothesis : rate limiting step : H - diffusion through the outer oxide layer H - diffusion under a constant and homogeneous electric field in the oxide layer Model of diffusion under a constant and homogeneous electric field (Fromhold equations) : Diffusion flux of the i species : Ci F Ji = -LiiGrad µ i Di i CiDie x RT Matter conservation equation in a steady state reaction system : Expression of the oxide growth rate after integration (by neglecting the H - concentration at the inner interface): dx dt V D e H C H r with r =-ef/rt X, the oxide thickness, D H, apparent diffusion coefficient, C H, H surface concentration exp( r X ) exp( r X ) C x i 3 mai 6 Ji = div i r C x M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 5
oxide thickness (µm) Description of the modelling Simulation of kinetic curve : - power law : X = k t n oxidation rate by the derivative of the fitted power : dx/dt 3,5 3,5,5,5 m m Chisq R y = m * M^m Value Error,468,57,4984,87,988 NA,99993 NA 4 6 8 t (d) 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 6
oxide growth rate (µm/d) Description of the modelling, dx/dt (µm/d) (M5 unirradiated) Expression of the oxide growth rate :,8,6 y = m*m*exp(m*m)/(exp(m... Value Error m,766,893 m -,554,758 Chisq,366 NA R,9955 NA dx dt V D e H C H r exp( r X ) exp( r X ),4 m m,,5,5,5 3 3,5 oxide thickness (µm) Fitted parameters : m m V r e D H C H. 5µm 76. µm. s e 7 V.cm - electric field against the H - transport M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 7
Description of the modelling How can irradiation modify the oxide growth rate? dx dt V e D H _ irr C H _ irr r' exp( r' X ) exp( r' X ) Modification of apparent diffusion coefficient : - Depending of irradiation defect concentration Modification of H - surface concentration : - niobium surface content - surface potential difference D ( t) D. f ( t) Nbseg _ irr H _ irr H d C H _ irr x x Nbseg _ unirr C H C 3 H 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 8
Description of the modelling How can irradiation modify the oxide growth rate? dx dt V e D H _ irr C H _ irr r' exp( r' X ) exp( r' X ) - r =-e F/RT? residual charge left by ion irradiation dx dt V 3 e D H C H f d ( t) r' exp( r' X ) exp( r' X ) 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 9
I/Imax (7cm-) Description of the modelling Fit of the irradiation defect fraction given by the inbtensity ratio of the 7 cm - RAMAN band intensity dx dt 3 f m, d ( t). m,, exp( m X ) exp( m X ), m m, V e r' D H C H,8 Y = M + M*x +... M8*x 8 + M9*x 9 M,994 M -,796 M,85 M3 -,793e-6 R,9966 t I7 f d ( t) P 9 I 7max ( t),6,4, I/Imax (7cm-) 3 mai 6 4 6 8 t (days) M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
oxide growth rate (µm/d) Description of the modelling Expression ( Eq. ) of the oxide growth rate after irradiation : dx dt 3 f m, d ( t). m,, exp( m X ) exp( m X ),, dx/dt (simulated curve using (Eq.) with m=.76 and m=-.8) dx/dt (µm/d) (M5 irrad He 7-exp) dx/dt (µm/d) (unirradiated M5-exp.) m = =.76 µm.s - m = -ef/rt=-.8 µm - e 436 V.cm - higher electric field against the H - transport,8,6,4, simulated curve irradiated M5 unirradiated M5 4 6 8 t (d) 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
Description of the modelling Comparison of the oxidation kinetic with the calculated curve X t dx dt dt calculated curve consistent with the oxidation kinetic after irradiation 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 3
Conclusions Raman Spectroscopy : good tool to detect irradiation defects Irradiation effect of the oxide : marked decrease of the oxidation rate of M5 High stability of irradiation defects in PWR conditions Long term kinetic effect of irradiation Proposition of a modelling compatible with the kinetic results 3 mai 6 M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 33
Perspective Perspective : Determine if the irradiation defects detected by RAMAN Spectroscopy are always present in neutron irradiated cladding M. TUPIN et al. th International Symposium on Zirconium in the Nuclear Industry 34