The present invention provides a communication system including a relay device that is capable of simplifying the configuration of a control device for controlling a device based on relay information and reducing cost of the whole system, the relay device and a method for controlling power supply. The bottom of the pedestal is provided with a flange, which is attached to the bottom of the process chamber by a flange holder. The melting process is successively repeated on new limited areas of the powder layer until a continuous layer of amorphous metal is formed. Each radio frequency device emits a signal with a given strength and identification to the air. A water-insoluble form of the radioactive material is formed on the substrate by chemical precipitation andor thermal decomposition.