Radiation detection systems
Continuous Radon Monitor
(Flow Through Type)
Continuous Radon Monitor (CRM-FTc) (Flow Through Type)
The Continuous Radon Monitor (CRM-FTc) is a microprocessor based radiation monitoring system that was developed by RDS for the monitoring of the radon activity concentration in outdoor and indoor air. The CRM-FTc is equipped with the low background "flow through" Lucas Cell and is powered by an internal 6V Pb 12 Ah battery.
The unit can operate continuously for approximately 4 days if the internal battery is fully charged. Nevertheless, the unit coupled with the supplied trickle charger can be used as the continuous radon activity concentration monitor for approximately 3 months if a 10 min logging option is chosen. If the 60 min logging option is chosen the system can continuously gather data for about 1 year.
Filtered air with radon is continuously sampled by the constant flow rate air sampler (the flow rate was set at 0.5 L/min). Whilst air flows through the Lucas Cell alpha particles emitted by radon and radon daughters inside the cell produce scintillations of light within the ZnS(Ag) scintillator coating of the Lucas Cell walls. The light pulses are detected by a PM tube and the voltage pulses are pre-amplified, amplified and alpha counts are logged into a memory chip. It is possible to store alpha counts either in the 10, 30, 60 or 120 min counting interval. The background count is subtracted from the total alpha count and the net count is multiplied by the count to the radon activity concentration conversion factor to obtain the radon activity concentration that is displayed and stored in the CRM memory. The LLD of the monitor is approximately 5-7 Bq/m3.
Note: The CRM can be used in the E-monitoring mode if it is coupled with the RDS E-Monitoring Interface. Monitoring data is sent to the RDS Monitoring platform via: