Report of investigation on malfunction of safety rod (occurred on June 17, 2004) in TRACY

Ad-hoc Committee for Investigation on Malfunction of Safety Rod in

A trouble, malfunction of a safety rod, occurred during transient operation of the Transient Experiment Critical Facility (TRACY) in Japan Atomic Energy Research Institute (JAERI) on June 17, 2004. JAERI organized its specialists into the ad-hoc committee for investigation on malfunction of a safety rod of TRACY on June 23, 2004, to understand the cause of the trouble and take countermeasures to prevent the issue. The ad-hoc committee held 11 meetings and had discussions on the trouble inquiring the situations of the TRACY operation and the results of examination from the division relevant to the TRACY. As the result of investigation the cause of the trouble was attributed to the following reason: The holding capability of the safety rod was temporarily depressed by a small piece of polyethylene sheet put between the electromagnet and armature of the safety rod, the polyethylene sheet which had been used in overhaul activities of the rod. In the present report, the detailed results of investigation and the countermeasures to prevent the trouble are described.