Oxidation behavior of Zry-4 in steam-air mixtures at high temperature

Conference · Fri Jul 01 00:00:00 EDT 2016

OSTI ID:22764101

Negyesi, M.; Amaya, M. ^[1]

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1. Nuclear Safety Research Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki, 319-1195 (Japan)

This study dealt with the oxidation behavior of Zry-4 nuclear fuel cladding under a severe nuclear reactor accident scenario occurring in a light-water reactor. Influence of the reaction extent on cladding mechanical properties was also treated. Zry-4 fuel cladding segments were exposed to steam atmosphere containing different amount of air in composition ranging from 0 to 100 vol. %. Exposure times covered both pre- and post-breakaway regimes. Metallographic observations along with microhardness testing were carried out to study the effect of air fraction on the material microstructure. Hydrogen pick-up was measured and residual mechanical properties were assessed employing Ring Compression Tests. The results show that the addition of air in steam can lead to more than 300 % increase of weight gain in case of ∼50 % or higher air fraction after the exposure of 60 min., namely, 'late post-breakaway regime'. Approximately three times thicker oxide scales were observed in such cases, indicating that most of the weight gain was due to the oxide layer increase. Nitride phase was preferentially observed close to the interface between oxide and metal layers. The α-Zr(O) sublayer thickness decreases with the increasing fraction of air in steam. Microhardness, measured within the prior β-phase region, slightly depends on the air fraction. Hydrogen uptake, on the other hand, depends strongly on the air fraction in steam. In the case of shorter exposure times, the effect of air addition in steam was suppressed. Eventually, specimen plastic strains drastically reduced in the late post-breakaway regime. (authors)

• Research Organization: American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22764101
• Resource Relation: Conference: TOP FUEL 2016: LWR fuels with enhanced safety and performance, Boise, ID (United States), 11-15 Sep 2016; Other Information: Country of input: France; 27 refs.; Related Information: In: TOP FUEL 2016 Proceedings| 1670 p.
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CLADDING
HYDROGEN
METALLOGRAPHY
MICROHARDNESS
MICROSTRUCTURE
MIXTURES
NITRIDES
NUCLEAR FUELS
OXIDATION
OXIDES
PLASTICITY
REACTOR ACCIDENTS
STEAM
STRAINS
TEMPERATURE RANGE 0400-1000 K
TESTING
WATER COOLED REACTORS
WATER MODERATED REACTORS
ZIRCALOY 4
ZIRCONIUM-ALPHA