Adhesive coating application for stainless welding lines of spent fuel pit

On March, 2000, during re-racking engineering of spent fuel pit (exchange engineering to dense rack for enforcement of storage capacity) at the Ikata Nuclear Power Station Unit-3 of the Shikoku Electric Power Co., Ltd., damages based on stress corrosion fracture caused by chlorides were found at two places near stainless lining (materials: SUS304) weld line of pit B under keeping in the air before use. Then, SEP decided to apply coating special epoxy resin developed by Framatome ANP GmbH (FANP) in Germany to all of weld lines of both pit A and B, for their protective maintenance measures, together with recovery of the damage portions. As the resin coating had an using result for about ten years by FANP out of Japan, it was the first operation in Japan, which was carried out on June to July, 2000 for pit B, and on November, 2000 to January, 2001 for pit A, to finish their engineerings as their plannings. Here were described features of the special epoxy resin, operation methods, and attention items on items on design and operations. (G.K.)