ISSN: 1546-962X
CODEN: JAIOAD
Published Online: 31 January 2005
Page Count: 24

Influence of Long Service Exposures on the Thermal-Mechanical Behavior of Zy-4 and M5™ Alloys in LOCA Conditions

Portier, L
Research Engineer, CEA/DEN, Service de Recherches Métallurgiques Appliquées, CEA/Saclay, Gif-Sur-Yvette,

Bredel, T
Research Engineer, CEA/DEN, Service d'Etudes des Matériaux Irradiés, CEA/Saclay, Gif-Sur-Yvette,

Brachet, J-C
Research Engineer, CEA/DEN, Service de Recherches Métallurgiques Appliquées, CEA/Saclay, Gif-Sur-Yvette,

Maillot, V
Research Engineer, CEA/DEN, Service de Recherches Métallurgiques Appliquées, CEA/Saclay, Gif-Sur-Yvette,

Mardon, J-P
Consulting Engineer, Framatome-ANP Nuclear Fuel, Lyon Cedex 06,

Lesbros, A
Consulting Engineer, Electricité de France, Service Etudes et Projets Thermiques et Nucléaires, Villeurbanne Cedex,

(Received 12 April 2004; accepted 18 July 2004)

Abstract

The main objective of this paper is to describe the effects of a long service exposure of the PWR fuel cladding tubes on their thermal-mechanical properties during and after a hypothetical LOCA transient. Within this prospect, specific studies have been performed: on one hand, thermal ramp tests under uniaxial stress loading on as-received, pre-hydrided and irradiated samples of Zy-4 and M5™, and on the other hand, mechanical tests after high temperature oxidation and quench on as-received and prehydrided Zy-4 and M5™. The main conclusions are:

(1) In service, hydrogen pick-up impacts the thermal ramp behavior under uniaxial stress loading of cladding tubes upon the first phase of LOCA transient, and the effect of the irradiation defects can be ignored for the conditions tested.

(2) As-received Zy-4 and M5™ achieve comparable post-quench mechanical behavior at 1000, 1100, and 1200°C for representative times of LOCA transient (1800 s).

(3) Oxygen has the most important effect in embrittlement of as-received Zr alloys at 1100 and 1200°C.

(4) Hydriding has no effect on the oxidation kinetics at 1200°C, but after quenching the hydrided materials become brittle at a lower weight gain than as-received materials; this embrittlement is due both to an intrinsic hydrogen-embrittlement effect and to the oxygen content increase resulting from the effect of hydrogen on its solubility in prior-Beta phase.

Keywords:
LOCA, zirconium alloy, creep, hydrogen effect, irradiation defects, Zy-4, M5™, high temperature oxidation, quench, residual ductility, embrittlement, oxygen content in prior-Beta phase

Paper ID: JAI12468
DOI: 10.1520/JAI12468
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