Mechanical behavior at high temperatures of highly oxygen- or hydrogen-enriched α and prior-β phases of Zirconium alloys - 2016-0063
- DEN, Service de Recherches Metallurgiques Appliquees, CEA, Universite Paris-Saclay, F-91191 Gif-sur-Yvette (France)
- MINES ParisTech, PSL Research University, Centre des Materiaux, CNRS UMR 7633, BP 87, 91003 Evry Cedex (France)
During a hypothetical loss-of-coolant accident, zirconium alloy fuel claddings can be loaded by internal pressure and exposed to steam at high temperatures (HTs) up to 1,200 deg. C and then cooled and quenched in water. A significant fraction of the oxygen that reacts with the cladding during HT oxidation diffuses beneath the oxide through the metallic substrate. This induces a progressive transformation of the metallic β{sub Zr}-phase layer into an intermediate layer of α{sub Zr}(O) phase containing up to 7 weight % (wt.%) oxygen. Furthermore, in some specific conditions, the cladding may rapidly absorb a significant amount of hydrogen during steam exposition at HTs. As a β{sub Zr} stabilizer, hydrogen would mainly diffuse and concentrate up to several thousands of parts per million by weight (wppm) into the inner β{sub Zr}-phase layer. This study intends to provide new and more comprehensive data on the HT mechanical behavior of the α{sub Zr}(O) and (prior-)β{sub Zr} phases containing high contents of oxygen and hydrogen, respectively. Model samples produced from M5{sup R} and Zircaloy-4 cladding tubes homogeneously charged in oxygen (less than or equal to 6 wt.%) and hydrogen (less than or equal to 3,000 wppm), respectively, were prepared. Their mechanical behavior was determined under vacuum between 800 and 1,100 deg. C for the oxygen-enriched α{sub Zr} phase and in air between 700 and 20 deg. C after cooling from the β{sub Zr} temperature domain for the hydrogen-enriched (prior-)β{sub Zr} phase. The α{sub Zr} phase was substantially strengthened and embrittled by oxygen. The contribution of the α{sub Zr}(O) layer to the HT creep behavior of an oxidized fuel cladding tube subjected to internal pressure is evaluated by finite element analysis. Mechanical strength and ductility of the model (prior-)β{sub Zr} phase appear to be affected by hydrogen contents of 2000-3000 wppm in ways that depend on temperature. (authors)
- Research Organization:
- ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA, 19428-2959 (United States)
- OSTI ID:
- 22788420
- Resource Relation:
- Conference: 18. International Symposium on Zirconium in the Nuclear Industry, Hilton Head, SC (United States), 15-19 May 2016; Other Information: Country of input: France; 68 refs
- Country of Publication:
- United States
- Language:
- English
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