Report on investigation of cause of crack at instrumentation pipe in JMTR. Data book on examination of pressure instrumentation pipe at JMTR hot laboratory

On December 10, 2002, the water leakage was found at the pressure instrumentation pipe attached to the exit pipe of No.1 charging pump of the purification system of a primary cooling system at JMTR, and the cracks were detected on the pressure instrumentation pipe by the visual observation. The Investigation Committee for Water Leakage from Instrumentation Pipe in JMTR was established and organized by specialists from inside and outside JAERI on December 16. In order to investigate the cause of crack initiation at the pressure instrumentation pipe, the Working Group was organized in the Department of JMTR. Visual observation, fractography test, metallographic and hardness test for the pressure instrumentation pipe and its weldment carried out in the JMTR Hot Laboratory. This report summarized above data obtained by investigation on the cause of the crack initiation. (author)