Prevention of false alarms from automatic fire alarm system in the Tokai Reprocessing Plant

Ishii, Takahiro ; Shimizu, Kazuyuki; Sakai, Katsumi; Inami, Shinichi

The automatic fire alarm system installed in the Tokai Reprocessing Plant consists of more than 5000 detectors in about 40 facilities for the moment. In this system, 51 non-fire cases have occurred for 8 years; 2001 Jan. to 2009 May, and about half of these cases was due to the condensation of water vapor generated on the sensor. Therefore, the prevention of condensation is necessary to reduce such false alarms, and the measure for prevention of condensation has been taken by installing a mount for the detector basement. This mount facilitates that the detector does not contact directly to the surface of ceiling where is likely to change an environment due to changeable temperature and humidity. As a result, false alarms caused by condensation have not been found on the detectors with the mounts. This paper reports the details of the improved fire alarm system, and cause/measures for false alarms.