Groundwater, Radon Continuous Monitoring System (α-scintillation Counting) for Natural Hazard Surveillance
A ``quasi continuous mode'' monitoring system to measure the radon concentration within a natural environment (mainly groundwater), was designed, assembled and tested, under collaboration between DINCE and ING, partly within the framework of two EC funded programs.The radon monitor consists of a customised discrete automatic sampler which produces a gas flux circuit, and an economical α-scintillation cell, coupled with a reliable electronics-photomultiplier assemblage. A convenient calibration system together with a temporised control system have been set up. The overall ``mean efficiency'' of the system was calculated to be 7.79+/-0.13 counts per minute (cpm) for each Bq/L.Taking into consideration the present and future requirements of a geochemical surveillance network to assess natural hazards, the prototype design evolved from the study of existing systems devoted to monitor radon concentration levels, which are critically reviewed within this paper.In response to the main prerequisite of a remote station: maximum remote sensor versatility preserving shared software and hardware for the network as a whole, this radon monitoring system was conceived as part of a multi-parametric Geochemical Monitoring System (GMS II) prototype, designed and realised as a test-stand for sensors (chemical, hydrological, geophysical, organic chemistry devoted, etc.) in continuous evolution throughout the international market.