The Mechanism of Localized In-pile Corrosion of Zirconium Alloys, (III)

Abstract

The electric charges to enhance the localized in-pile corrosion are estimated quantitatively by a model analogous to an electric circuit. The model is more detailed than that reported in the previous papers. It is applied to the cases of a fuel cladding near platinum in the Halden experiments and a fuel channel near a control blade. As a result, respecting the electric charges to enhance the localized oxidation, both cases investigated in this work are explained quantitatively by the total amount of electric current, from all the localized electrochemical cells between the surface of zirconium oxide adjacent to and facing to bare and grounded metals such as platinum or stainless steel and its neighboring parts, introduced by the “β-induced electric fields” on zirconium oxide.

The electric potential of the electrochemical cell concerned decreases in the course of oxidation, and therefore, the retardation of oxidation during the growth of the oxide film can be explained by the fact that the electric current by the above electrochemical cell becomes insufficient to enhance the localized oxidation.

KEYWORDS:

• zirconium alloys
• fuel channel
• stainless steels
• shadow phenomena
• in-pile corrosion
• enhanced corrosion
• adjacent effects
• beta-particles
• electric field
• calculation
• oxidation
• electric potential