RECENT STUDIES OF PRE-FILMING TECHNIQUE FOR LIGHT WATER-REACTOR MATERIALS

Reduction of radiation exposure is one of the most important subjects of light water reactor (LWR) plants as well as improvements of reliability and availability. Several methods, for suppressing corrosion and deposition of radioactive ions, have been proposed and applied to some actual plants. The following recent studies of the pre-filming technique for LWR materials were presented from a point of view of the surface film in this paper. (1) Zinc and Aluminum ion injection methods. (2) Oxidation treatment in high temperature dissolved oxygen controlled water. (3) Pre-oxidation treatment by the RCT method. (4) Palladium coating treatment. (5) Pre-oxidation treatment in air or steam atmosphere. (6) Pre-oxidation treatment in low-oxygen potential atmosphere. It may be concluded that the key factors controlling the metal dissolution in high temperature water are thickness and denseness together with chemical composition of the oxide films.