412
Ind. Eng. Chem. Res. 1998, 37, 412-419
Preparation and Reactivity of Lepidocrocite under Simulated Feedwater Conditions G. Bryce McGarvey* Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, Ontario, Canada K0J 1J0
K. Barrie Burnett and Derrek G. Owen Atomic Energy of Canada Limited, Whiteshell Laboratories, Pinawa, Manitoba, Canada R0E 1L0
Lepidocrocite (γ-FeOOH), prepared using several different aging temperatures and aging times, possesses widely varying morphological and structural features. Mean particle dimensions and surface areas were all found to depend on the conditions of the synthesis. Studies of the aqueous reduction of several of the lepidocrocite samples to magnetite indicated that the initial steps in the dissolution-reprecipitation process were influenced by the crystallinity of the material. Results of the morphological studies and the transformation reaction studies are described within the context of corrosion-product generation and stability in secondary feedwater systems of pressurized heavy-water nuclear reactors. Introduction In CANDU (CANDU is a registered trademark of Atomic Energy of Canada Limited) generating stations, the secondary feedwater piping and the shells of the major feedwater heaters and steam generator components are constructed from carbon steel. When carbon steel corrodes, the final distribution of products will to a large extent reflect the environment that the metal was exposed to during the degradation process. Complex corrosion phenomena are encountered in aqueous environments due to changing redox conditions and levels of impurities. Despite operating with low impurity levels (
