ISSN: 1546-962X
Page Count: 17

Shadow Corrosion Mechanism of Zircaloy
Lysell, G
Studsvik Nuclear AB,

Nystrand, A-C

Ullberg, M

Abstract

The mechanism of Zircaloy shadow corrosion was studied theoretically and experimentally. The theoretical study showed shadow corrosion, with a few exceptions, to be remarkably consistent with a galvanic corrosion mechanism. The exceptions may be explained as radiation effects. An experiment was therefore devised to test the galvanic hypothesis, based on the fact that galvanic corrosion requires a closed current loop. Three pieces of Zircaloy cladding with stainless steel counter electrodes were exposed in-pile. Two of the claddings were galvanically coupled to the counters. The third cladding was well insulated by fitting it to a 100 mm sapphire tube. The claddings were irradiated together in oxidizing water chemistry for one reactor period. The galvanically coupled claddings developed shadow corrosion, but not the well insulated cladding.

Keywords:
Zircaloy, shadow corrosion, cladding, radiation, boiling water reactor

Paper ID: JAI12374
DOI: 10.1520/JAI12374
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