SYMPOSIA PAPER Published: 01 February 2018
STP159720160067

Preliminary Irradiation Effect on Corrosion Resistance of Zirconium Alloys

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In order to improve the composition and structure of zirconium alloys, it is important to know how changes in their structure-phase state under irradiation affect various properties, including corrosion. In this work, autoclave corrosion tests were carried out on fuel cladding samples made of zirconium-niobium and zirconium-niobium-tin-iron alloy systems. All samples were preliminarily irradiated in a BOR-60 nuclear reactor at a fluence of 2 × 1026 m−2 (E > 0.1 MeV). The autoclave tests of irradiated and unirradiated samples were performed at 350°C for 240 days in distilled water containing 10 ppm lithium and 1,600 ppm boron.

The irradiation of all alloys resulted in a significant change in their initial structure-phase state. The content of niobium in β-niobium–phase precipitates was reduced from 80 % to −90 % to 50 % to −60 %. Iron atoms from the Laves-phase particles were diffused into a matrix, and their lattice transformed from hexagonal close-packed to body-centered cubic. An average size of the transformed second-phase precipitates in the irradiated alloys increased relatively to an average size of the initial precipitates. Elongated radiation-induced precipitates (RIPs) with an average length up to 7 nm were formed in all alloys under irradiation. In comparison with the unirradiated state, irradiation reduced the corrosion of zirconium-niobium alloys, and this effect became more apparent with increased niobium content in the alloy.

For zirconium-niobium-tin-iron alloys, irradiation led to more severe corrosion, mostly because of increasing tin content. Niobium content increased up to 2.37 %, and iron content decreased up to 0.18 % in the alloys, contributing to higher corrosion resistance. An interconnection between the niobium/(tin + iron) alloying parameter, quantity of nanometric precipitates formed therein under irradiation, and their corrosion performance has been suggested.

Author Information

Markelov, Vladimir
SC VNIINM, Moscow, RU
Novikov, Vladimir
SC VNIINM, Moscow, RU
Shevyakov, Alexandr
SC VNIINM, Moscow, RU
Gusev, Anatoly
SC VNIINM, Moscow, RU
Peregud, Michael
SC VNIINM, Moscow, RU
Konkov, Viktor
SC VNIINM, Moscow, RU
Eremin, Sergey
SC SSC RIAR, Dimitrovgrad, RU
Pokrovsky, Alexander
SC SSC RIAR, Dimitrovgrad, RU
Obukhov, Alexander
SC SSC RIAR, Dimitrovgrad, RU
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Developed by Committee: B10
Pages: 857–880
DOI: 10.1520/STP159720160067
ISBN-EB: 978-0-8031-7642-3
ISBN-13: 978-0-8031-7641-6