| 摘要 |
PROBLEM TO BE SOLVED: To immobilize a radioactive substance in reactor water without increasing a manufacturing cost by forming an oxide film on the outer surface of a cladding tube under conditions where a specific DC voltage is applied in the electrolyte of neutral salt. SOLUTION: A metal frame 13 where a plurality of cladding tubes 1 are arranged is suspended in a conductive anode oxide bath 10 with an electrolyte 11 containing, for example, 0.1% boric acid ammonium. The upper edge of the covering pipe 1 is connected to the metal frame 13, and a watertight plastic plug 14 is provided at the lower edge of the cladding tube 1. For example, a 300V DC voltage is applied to the cladding tube 1 for five minutes that is an anode, thus performing the anode oxidation of the outer surface of the cladding tube 1. After the anode oxidation, the cladding tube 1 is withdrawn from the anode oxide bath 10 and is washed before shifting to an edge part cutting process. Although a part without any oxide film is formed at the upper edge part of the cladding tube 1 by this method, the area of this part is small, so that the function for immobilizing a radioactive substance in a reactor water onto the outer surface of the cladding tube 1 can be obtained fully. |
