To provide a method and a system for preventing ozone from flowing out in an electron beam irradiator which keep ozone from flowing out to an accelerator chamber and can prevent devices in the accelerator chamber from corroding.
The system for preventing the ozone generated in an electron beam irradiation chamber where an object is irradiated with an electron beam from flowing out to the electron beam accelerator chamber is characterized in that the system includes a detection means 25 which detects the pressure or the concentration of ozone in the electron beam irradiation chamber 23 and a warning means 25 which produces warning signals in stages when the detected pressure is below a prescribed level or when the concentration of ozone is above a prescribed level, the detection means 25 has detection areas and a means 29 for controlling a wind flow which carries out either the increase in the wind flow (A) in the accelerator chamber or the swept volume (B) of ozone or the decrease in a wind flow (C) in the electron beam irradiation chamber or both of them so that the atmospheric pressure in the accelerator chamber 23 is higher than that in the electron beam irradiation chamber 24 on the basis of the detected value when the pressure or the concentration of ozone reaches a first prescribed level is provided.