The Mechanism of Localized In-pile Corrosion of Zirconium Alloys

Abstract

The role of β-particles for the localized in-pile corrosion of components made of zirconium alloys, such as fuel channels closely facing stainless steel components, has been discussed and the distribution of β-particles near fuel channels has been evaluated using a multi-layer calculation method.

It is shown that electric charges which come from β-particles produced mainly by the Compton effect, but not by β-emitting radionuclides, make electric fields in and on the zirconium oxide surfaces in the reactor by a model analogous to an electric circuit, and that these electric fields induced by β-particles could be essential for the understanding of localized in-pile corrosion of zirconium alloys. The mechanism of the localized in-pile corrosion of zirconium alloys adjacent to other welded alloys is also discussed as an enhanced corrosion by electric potentials using the proposed electric circuit model in detail.

KEYWORDS:

• zirconium alloys
• fuel channels
• stainless steels
• weld shadow
• shadow phenomena
• in pile corrosion
• enhanced corrosion
• adjacent effects
• beta particles
• electric fields
• calculations