Swedish Nuclear Power Station On-Line Isotopic Stack Monitoring System

The system described here was developed to continuously monitor the release of radioactivity to the environment through the stack ventilation systems of a Swedish multi-unit reactor site. The use of detectors of different sensitivities enables the system to operate under both normal and emergency conditions. Redundancy is obtained by having each reactor´s effluent monitored simultaneously by two computers, each having its own data base. If one computer stops, it will restart automatically and recover missing information from the other computer´s data base. Fiber optics are used for control and data communication between computers and between computers and remote acquisition MCA´s. Data is continuously summed, averaged, and updated; and at the user´s request a comprehensive set of hourly, daily, monthly, and yearly radiation and critical-group dosage reports can be generated.