INFLUENCE OF STEAM PRESSURE ON THE HIGH TEMPERATURE OXIDATION AND POST-COOLING MECHANICAL PROPERTIES OF ZIRCALOY-4 AND M5 CLADDING (LOCA CONDITIONS) M. Le Saux 1*, V. Vandenberghe 1, P. Crébier 2, J.C. Brachet 1, D. Gilbon 1, J.P. Mardon 3, P. Jacques 4, A. Cabrera 4 1 CEA, DEN, 91191 Gif-sur-Yvette Cedex, France 2 CEA, DEN, 38054 Grenoble Cedex 9, France 3 AREVA, AREVA NP SAS, Fuel Business Unit, 69546 Lyon Cedex 06, France 4 EDF-SEPTEN, 69628 Villeurbanne Cedex, France * E-mail: matthieu.lesaux@cea.fr 17 TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD, INDIA 20 FÉVRIER 2013 PAGE 1 M5 is a trademark of AREVA NP registered in the USA and in other countries
INTRODUCTION LOss of Coolant Accident (LOCA) in Light Water Reactors Zirconium alloys fuel claddings exposed to steam at High Temperature (HT, up to 1200 C) until quenching Most studies focused on the Large Break LOCA conditions and thus performed at atmospheric pressure Intermediate Break LOCA (IB-LOCA) conditions Core uncovery occurs at relatively high primary pressure (several tens of bars up to ~80 bar) Sometimes observed that steam pressure could have a significant effect on the HT oxidation of zirconium alloys 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 2
INTRODUCTION Effect of steam pressure on the HT oxidation of Zr alloys Scarce data and scattering and discrepancies from one study to another (e.g. Vrtilkova et al. (Nuclear Fuel Institute), Park et al. (Kyung Hee University) ) Dependence on the oxidation temperature and the alloy (Zircaloy-4, E110, ZIRLO ) Oxide layer formed and hydrogen absorbed during in-service operation Potential influence on the steam pressure effect (burn-up dependence) Origin of the steam pressure effect not clear so far ZIRLO is a trademark of Westinghouse Electric. E110 is a trademark of A.A. Bochvar VNIINM. 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 3
INTRODUCTION Main objectives of this study For low-tin Zircaloy-4 and M5 : Influence of steam pressure (from 1 to 80 bar) on the oxidation and hydrogen pick-up at HT (between 750 and 1200 C) post-cooling mechanical properties Impact on the steam pressure effect of representative in-service hydriding (~ the end-of-life hydrogen contents expected for high BU cladding) oxidation (oxide layers thicknesses limited to 8 µm in this study) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 4
OUTLINE Materials and experimental procedure Oxidation kinetics and hydrogen pick-up Oxide layer and oxygen diffusion Mechanisms responsible for the steam pressure effect? Conclusions 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 5
MATERIALS AND EXPERIMENTAL PROCEDURE Materials Stress-Relieved Annealed low-tin Zircaloy-4 (Zy-4) and fully recrystallized M5 cladding tube specimens (AREVA) Material Zircaloy-4 M5 Nominal chemical composition (in wt.%) Material Sn Fe Cr Nb O Zr Zircaloy-4 1.3 0.2 0.1-0.13 Bal. M5 TM - 0.04-1.0 0.14 Bal. State Oxide thickness Hydrogen content As-Received (AR) - - Pre-hydrided - 500-600 wt.ppm Pre-oxidized 3 and 8 µm <100 wt.ppm As-Received (AR) - - Pre-hydrided - 190-230 wt.ppm Pre-oxidized 3 and 5 µm <100 wt.ppm 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 6
MATERIALS AND EXPERIMENTAL PROCEDURE Materials Stress-Relieved Annealed low-tin Zircaloy-4 (Zy-4) and fully recrystallized M5 cladding tube specimens (AREVA) Hydrogen charging in an argon/hydrogen mixture at 400 C (AREVA/CEZUS Paimboeuf) Nominal chemical composition (in wt.%) Material Sn Fe Cr Nb O Zr Zircaloy-4 1.3 0.2 0.1-0.13 Bal. M5 TM - 0.04-1.0 0.14 Bal. Material State Oxide Hydrogen thickness content As-Received (AR) - - Zircaloy-4 Pre-hydrided - 500-600 wt.ppm Pre-oxidized 3 and 8 µm <100 wt.ppm As-Received (AR) - - M5 Pre-hydrided - 190-230 wt.ppm Pre-oxidized 3 and 5 µm <100 wt.ppm 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 7
MATERIALS AND EXPERIMENTAL PROCEDURE Materials Stress-Relieved Annealed low-tin Zircaloy-4 (Zy-4) and fully recrystallized M5 cladding tube specimens (AREVA) Hydrogen charging in an argon/hydrogen mixture at 400 C (AREVA/CEZUS Paimboeuf) Two-side pre-oxidation in static autoclave at 360 C with typical PWR primary water chemistry (1000 ppm B, 2.2 ppm Li and 30 cc/kg H 2 ) (EDF R&D) Material Zircaloy-4 M5 Nominal chemical composition (in wt.%) Material Sn Fe Cr Nb O Zr Zircaloy-4 1.3 0.2 0.1-0.13 Bal. M5 TM - 0.04-1.0 0.14 Bal. State Oxide thickness Hydrogen content As-Received (AR) - - Pre-hydrided - 500-600 wt.ppm Pre-oxidized 3 and 8 µm <100 wt.ppm As-Received (AR) - - Pre-hydrided - 190-230 wt.ppm Pre-oxidized 3 and 5 µm <100 wt.ppm Pre-transient oxide layers homogeneously smooth and black/dark grey 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 8
MATERIALS AND EXPERIMENTAL PROCEDURE High temperature oxidation and cooling Double-side oxidation in a flowing steam environment in the CINOG HP facility (CEA) Oxidation temperatures (T): 750, 850, 900, 1000, 1100 and 1200 C Steam pressures (P): 1, 10, 20, 40, 60 and 80 bar Oxidation times (t): 200, 400, 600, 1800, 3600, 7200, 9000 and 18000s Steam inlet Sample and quartz tube Condenser Cooling, quite fast (~100-150 C/s down to 500 C) but slower than during a direct water quenching 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 9
OUTLINE Materials and experimental procedure Oxidation kinetics and hydrogen pick-up Oxide layer and oxygen diffusion Mechanisms responsible for the steam pressure effect? Conclusions 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 10
OXIDATION KINETICS AND HYDROGEN PICK-UP At atmospheric pressure 15 1200 C 1100 C Zy-4, 1 bar Results in good agreement with data previously 10 obtained in other CEA facilities Oxidation kinetics sub-parabolic (n 2.6) between 700 and 900 C and nearly parabolic (n 2) between 1000 and 1400 C 1 n Wg Kt Oxidation kinetics faster for fresh Zy-4 than for fresh M5 for T below 1100 C, nearly the same for both materials at higher h T For both materials, Wg lower than those predicted by the Baker-Just (BJ) correlation whatever T, not far from the Cathcart-Pawel (CP) correlation beyond 1000-1100 C and lower below No hydrogen uptake at HT (pre-breakaway oxidation regime) Weight gain (mg/c cm 2 ) Weight ga ain (mg/cm 2 ) 5 0 15 10 5 0 900 C 850 C 750 C 1000 C CINOG BP - - DEZIROX 1 Symbols: This study 0 1000 2000 3000 4000 Oxidation time (s) M5, 1 bar 1100 C 1200 C CINOG BP - - DEZIROX 1 Symbols: This study 900 C 850 C 750 C 1000 C 0 1000 2000 3000 4000 Oxidation time (s) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 11
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of P on fresh Zy-4 (1/3) 750-1000 C: Oxidation kinetics enhanced under high P, since the early stages of oxidation ( 200s) Wg under high P (>60 bar) slightly greater than those predicted by the BJ correlation 1100 and 1200 C: Effect of P quite low or negligible No significant effect of P on the exponent n of the general oxidation kinetics model Weight gain (mg g/cm 2 ) Weight gain (mg/cm 2 ) 6 0.6 20 Zy-4, 850 C 3600s BJ 3600s 1800s BJ 1800s 600s BJ 600s 200s P BJ 200s 0 20 40 60 80 Steam pressure (bar) Zy-4, 1100 C P BJ 400s 400s BJ 200s 200s 2 0 20 40 60 80 Steam pressure (bar) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 12
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of P on fresh Zy-4 (2/3) Dependency of Wg on P nearly exponential P effect increases with increasing t, significantly at the beginning of oxidation and slower after (kind of saturation as the oxide growths) 0.6 P effect maximal at 850 C but does not change so much between 750 and 1000 C Norm malized steam pre essure effect parameter, α (-) 1 0.8 0.4 0.2 0-0.2-0.4 Wg T, t, P Wg T, t,1 Zy-4 exp Park et al. T, t P 1 Steam pressure effect parameter 1100 C t 850 C 900 C 1000 C 750 C 0 1200 1000 C 2000 3000 4000 Oxidation time (s) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 13
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of P on fresh Zy-4 (3/3) Increase of Wg with increasing P associated with a significant but limited hydrogen pick-up The higher the P, the greater the hydrogen uptake (no hydrogen uptake at 1 bar) Hydrogen uptake increases during oxidation Hydrogen pick-up fraction relatively low (ratio of hydrogen absorbed by the material and hydrogen released during oxidation <10%) en content (wt.pp pm) Hydrog 350 300 250 200 150 100 50 0 Zy-4 t 80 bar P 40 bar 1 bar 0 10 20 30 40 50 60 70 (Oxidation time (s)) 1/2 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 14
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of P on fresh M5 750-1200 C: P effect quite low or negligible Wg lower than those predicted by the BJ correlation No significant effect of P on the exponent n of the general oxidation kinetics model Weight gain (mg g/cm 2 ) 6 0.6 20 M5, 850 C BJ 3600s 7200s BJ 1800s 3600s 1800s BJ 600s 600s P BJ 200s 200s 0 20 40 60 80 Steam pressure (bar) M5, 1100 C No significant hydrogen uptake whatever the oxidation conditions Weight gain (mg/cm 2 ) P BJ 400s BJ 200s 400s 200s 2 0 20 40 60 80 Steam pressure (bar) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 15
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of pre-hydriding at 850 and 1000 C For both Zy-4 and M5, no significant impact of pre-transient hydriding (gaseous charging) )up to end-of-life hydrogen contents on the oxidation kinetics hydrogen uptake steam pressure effect P effect important for Zy-4 and much less significant for M5, whether the material is pre-hydrided or not Weight gain (mg g/cm 2 ) Weight gain (mg/cm 2 ) 10 1 10 Zy-4 Fresh Pre-H. 600 wt.ppm 1000 C 400s 1000 C 200s 850 C 600s 0 20 40 60 80 Steam pressure (bar) M5 Fresh Pre-H. 150 wt.ppm 1000 C 400s 1000 C 200s 1 850 C 600s 0 20 40 60 80 Steam pressure (bar) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 16
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of a thin pre-oxide layer at 850 and 1000 C (1/2) For both materials, for the same ox. conditions under 1 or 80 bar, Wg lower for the pre-oxidized samples (the thicker the pre-ox. layer, the greater the decrease in Wg), at least for short t t 0 Steam t 1 >t 0 Steam O 2 O 2 Pre-ox. β Zr (+α Zr ) Pre-ox. HT ox. α Zr (O) β Zr (+α Zr ) Wg of pre-ox. materials substantially lower than those predicted by the CP and BJ correlations, even for P as high as 80 bar In the case of pre-ox. materials, for a given preoxide layer thickness, Wg of M5 close to those of Zy-4, whereas lower in the case of non pre-ox. materials ae as( (decrease in Wg due to pre-ox. lower for M5 1 than for Zy-4 for the conditions investigated) O Weight gain (mg g/cm 2 ) Weight gain (mg/cm 2 ) 10 1 10 Fresh Pre-ox. ~3 µm Pre-ox. ~8 µm BJ CP BJ CP Fresh Pre-ox. ~3 µm P Pre-ox. ~8 µm Zy-4, 1000 C, 400s 0 20 40 60 80 Steam pressure (bar) Fresh M5, 1000 C, 400s Pre-ox. ~3µm Pre-ox. ~5 µm BJ CP BJ CP Fresh Pre-ox. ~3 µm Pre-ox. ~5 µm P 0 20 40 60 80 Steam pressure (bar) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 17
OXIDATION KINETICS AND HYDROGEN PICK-UP Effect of a thin pre-oxide layer 0.8 at 850 and 1000 C (2/2) 0.6 P effect on the oxidation of Zy-4 reduced in the presence of a thin pre-oxide layer Differences between sensitivities of Zy-4 and M5 to P significantly smaller after pre-oxidation For the same oxidation conditions, hydrogen pick- up of pre-oxidized ed Zy-4 under 80 bar (no hydrogen uptake at 1 bar) lower than those of the fresh or pre-hydrided material, in correlation with the lower Wg No significant hydrogen uptake at HT in the case of pre-oxidized M5 essure effect (-) rmalized steam pre parameter, α Nor Hydrogen pic ck-up (wt.ppm) 1 0.4 0.2-0.4 Zy-4 --- 850 C 600s 1000 C 400s 0 0 2 4 6 8-0.2 M5 200 180 160 140 120 100 80 60 40 20 Zy-4 Pre-oxide thickness (µm) Pre-ox. ~3µm 850 C 80 bar Fresh 1 bar 80 bar 1000 C 80 bar 0 1b bar 0 2 4 6 8 10 Weight gain (mg/cm 2 ) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 18
OUTLINE Materials and experimental procedure Oxidation kinetics and hydrogen pick-up Oxide layer and oxygen diffusion Mechanisms responsible for the steam pressure effect? Conclusions 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 19
OXIDE LAYER AND OXYGEN DIFFUSION Oxide and metallic layers thicknesses Fresh M5 1 bar 80 bar Oxide layer Oxide layer Measured oxide layers thicknesses in accordance with Wg: not significantly modified by the increase in P at 850, 1000 or 1200 C for M5 increase with increasing P at 850 and 1000 C but not at 1200 C for Zy-4 25 µm Fresh Zy-4 Oxide layer Oxide layer Enhanced oxidation kinetics of Zy-4 under high P at 850 and 1000 C not associated with additional oxygen diffusion through the metallic substrate concentration (-) Normalized oxygen 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 1 bar 80 bar Zy-4 850 C 3600s 0 0 50 100 150 200 250 300 Distance from the initial outer surface (µm) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 20 1 bar 80 bar
OXIDE LAYER AND OXYGEN DIFFUSION Morphology of the oxide layers For both materials, whatever T and P, columnar structure of the oxide 1 bar 80 bar M5 : No significant effect of P on the morphology, porosity or damage of oxide layers formed between 750 and 1200 C Fresh M5 Zy-4: Oxides formed under high P between 750 and 1000 C are more stratified and exhibit more pores and cracks show crystallites smaller and more disorganized and disoriented with grain boundaries not defined as well as in the oxides formed at 1 bar Fresh Zy-4 2 µm Observations performed after cooling and mechanical testing Additional pores and cracks 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 21
OUTLINE Materials and experimental procedure Oxidation kinetics and hydrogen pick-up Oxide layer and oxygen diffusion Mechanisms responsible for the steam pressure effect? Conclusions 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 22
MECHANISMS RESPONSIBLE FOR THE STEAM PRESSURE EFFECT? Mechanisms inherent to the P effect take place at the early stage of oxidation Oxidation mechanisms not fundamentally under high P and atmospheric P Influence of P on the reaction at the outer oxide/steam interface and/or on the oxygen transport through the existing oxide but not on the reaction at the inner M/O interface and the oxygen diffusion beneath it Alloy dependent influence of P on the microstructure of the oxide formed at HT (and thus on the oxygen diffusion through it) but not really on the oxygen transport rate through the pre-existing scale (rate limiting process until complete reduction of the pre-oxide) Oxide layer formed under high P still partially protective 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 23
MECHANISMS RESPONSIBLE FOR THE STEAM PRESSURE EFFECT? Oxide morphology, porosity and cracking P effect associated with a faster development within the oxides formed under high P of porosities and micro-cracks Easier access of oxygen and hydrogen atoms to the metallic substrate Oxide grains morphology and orientation modified under high P Steam diffusion and pores formation at grain boundaries and inter-granular cracking facilitated 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 24
MECHANISMS RESPONSIBLE FOR THE STEAM PRESSURE EFFECT? Oxide phases and stoichiometry and metallic substrate Potential influence of P on the stability of the tetragonal phase of zirconia (metastable below 1000 C) and/or on the tetragonal to monoclinic phase transformation Additional stresses and formation of pores or even cracks Effect of P on the oxide stoichiometry t (oxygen vacancies) May influence atoms diffusion through the oxide, stability of zirconia tetragonal phase and/or oxide plasticity (sometimes, whitish color of the outer surface of the oxide layers formed on Zy-4 under high P) P effect potentially related to the evolution of the characteristics and the resulting properties of the metallic substrate, in particular at the beginning of the ox. process (750-1000 C: metallic substrate in α Zr phase or two-phases (α Zr +β Zr ) + dissolution of some intermetallic precipitates in Zy-4 and apparition of Nb-enriched β Zr phase in M5 ) 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 25
OUTLINE Materials and experimental procedure Oxidation kinetics and hydrogen pick-up Oxide layer and oxygen diffusion Mechanisms responsible for the steam pressure effect? Conclusions 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 26
CONCLUSIONS Oxidation kinetics and hydrogen pick-up Under high h P between 750 and 1000 C, oxidation kinetics of as-fabricated lowtin Zy-4 enhanced and combined with a significant but limited hydrogen uptake since the early stages of oxidation P effect quite low or negligible between 750 and 1000 C for as-fabricated M5, and at 1100 and 1200 C for both alloys P has potentially an effect on the oxidation rate but does not really modify the (sub-) parabolic oxidation kinetics Oxidation kinetics, hydrogen uptake and effect of P not significantly modified by in-service pre-hydriding (gaseous charging) up to the end-of-life hydrogen contents expected for Zy-4 and M5 Weight gains at 850 and 1000 C lower for materials with thin pre-oxide layers (3 to 8 µm thick, formed in autoclave at 360 C with typical PWR primary water chemistry) and between sensitivities of Zy-4 and M5 to P significantly reduced after pre-ox. in the thickness range investigated t 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 27
CONCLUSIONS Oxide layer, oxygen diffusion and mechanisms potentially responsible for the P effect Enhanced oxidation kinetics of Zy-4 under high P correlated with a thickening of the oxide layers formed at HT but not associated with additional oxygen diffusion through the metallic substrate P has an influence on the microstructure (crystallites morphology, porosity and cracks) of the oxide formed within the 750-1000 C T range on Zy-4, but not on M5 Assumptions: Changes in oxide microstructure, probably responsible for a faster oxygen (and hydrogen) transport through the oxide layer, potentially induced by a destabilization promoted under high P of the tetragonal phase of zirconia? 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 28
CONCLUSIONS Post-cooling mechanical properties and P effect consequences during in-reactor transients Effect of P on the post-cooling mechanical properties (ring compression tests at 20 and 135 C) of fresh, pre-hydrided and pre-oxidized Zy-4 and M5 oxidized at HT generally limited it for the conditions investigated t According to calculations, impact of the P effect for Zy-4 very low or negligible on the ECR actually achieved during typical in-reactor transients No consequence on LOCA related criteria verification 20 17TH FÉVRIER INTERNATIONAL 2013 SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD PAGE 29
Thank you for your attention PAGE 30 17TH INTERNATIONAL SYMPOSIUM ON ZIRCONIUM IN THE NUCLEAR INDUSTRY, FEBRUARY 03-07, 2013, HYDERABAD Commissariat à l énergie atomique et aux énergies alternatives Centre de Saclay 91191 Gif-sur-Yvette Cedex T. +33 (0)1 69 08 12 28 F. +33 (0)1 69 08 71 67 Direction de l Energie Nucléaire Département des Matériaux pour le Nucléaire Service de Recherches Métallurgiques Appliquées 20 FÉVRIER 2013 Etablissement public à caractère industriel et commercial RCS Paris B 775 685 019