抄録
This study investigated the strength of piping in boiling water reactors (BWRs) subjected to detonation of flammable gas that accumulates in piping. Accumulated gases in the piping of BWRs are stoichiometric hydrogen-oxygen and steam. Stoichiometric hydrogen-oxygen gas and about 5% nitrogen gas were detonated in carbon steel pipes with an initial pressure from 2.5 to 4.0 MPa at room temperature (RT) in our experiment. Plastic strains were measured with strain gauges and the behaviors of pipe ruptures were recorded with a high speed camera. Pipe specimens were ruptured rapidly with large plastic circumferential strain of more than 8 %. A dimple pattern was observed in the fracture surfaces. Therefore, we found that the fracture mode of carbon steel pipes under detonation pressure is ductile fracture. The pressure of the reflected wave at the closed end is so high that pipes attached to closed valves deform the most when hydrogen-oxygen gas detonates in piping.
