Effective utilization of concrete debris generated from nuclear reactors; Clearance of concrete debris generated from modification work of JRR-3

Kishimoto, Katsumi ; Satoyama, Tomonori ; Takaizumi, Hirohide; Kanno, Tomoyuki; Maruyama, Tatsuya; Yoshimori, Michiro

We have been storing about 4000 tons of very low-level radioactive concrete debris as radioactive wastes generated from the modification of JRR-3 between 1985 and 1990. At that time, the clearance system was not a part of our regulatory law. We conducted a preliminary survey of contamination levels, and then established procedures for measuring and evaluating the radioactivity concentration. In 2008, the government authorized our procedures for clearance. Since FY 2009, we have measured the radioactivity concentration of concrete debris, using the government-authorized procedures. By the end of FY 2012, the government had confirmed the correctness of our measurements and evaluation results on about 1900 tons of concrete debris. We processed the concrete debris that was approved by the government for recycling. By the end of FY 2012, we had reused about 600 tons of concrete debris as backfilling material in depressed areas around buildings in the Nuclear Science Research Institute.