Real-Time Perimeter Gamma Radiation Monitoring System

In the aftermath of the TMI incident, considerable concern has emerged on the effectiveness of offsite radiation monitoring in response to nuclear accidents. This concern is reflected in a number of NRC publications, in particular Regulatory Guide 1.97. The system described here meets the requirement of this new regulation in providing continuous gamma monitoring of the reactor environs over the range of 1 ¿R/h to 10 R/h. Remote stations (up to 16) are permanently installed at the reactor perimeter and consist of two ion chambers and a microprocessor-based signal processor. The data is transmitted via telephone or hardwired modems or telemetry to a central processing center (CPC). At the CPC the data is reduced, stored, and presented in a format to provide the user with a continuous update on gamma radiation levels in the environment during routine and emergency conditions.