12th Workshop on Accelerator Operations

A high-power pulsed modulator was burnt at the accelerating structure assembly room adjacent to the electron positron injector linac building in KEK. It is considered that a capacitor in the pulse forming network was broken and caught fire. The container of the capacitor was plastic material and was filled with insulating oil that are combustible. The fire generated much carbon soot and some chemicals and they sneaked into the injector building. The operation of those facilities was interrupted. The fire and its recovery are reported.