System RM - 3 – Continuous measurement of soil-gas radon concentration

 experimental device for in situ long-term measurement of SOIL-GAS radon concentration

Unique characteristics of the device

The measuring system RM – 3 is designed for the continuous soil-gas radon concentration measurement as one of the fundamental radon diagnosis method. The detection principle is based on an airflow ionization chamber operating in the current mode.

The new experimental device provides the monitoring of short-term and long-term radon variations in the subsoil of buildings. In addition, the monitoring system enables the investigation and analysis of radon entry parameters and characteristics relating to variable weather conditions and residential habits.

MAIN SYSTEM COMPONENTS AND PROPERTIES

·         Detector – airflow ionization chamber (sensitive detection volume 2.2 l)

·         Control and operation unit – an electrometer device with the data logger

·         Membrane pump with the electronic feedback regulation

·         Electronic flow meter with the memory storage

·     Unique sampling technical arrangements – the take-off probe special end fitting providing the defined continuous close circuit sampling

·      Thoron (220Rn) suppression unit – thoron additional signal is eliminated by its radioactive decay in the retarding piping system inserted in the close circuit

The special sampling procedure effectively eliminates the ambient atmosphere influence on the long-term soil-gas sampling (temperature and pressure fields effects) and the close circuit with defined flow characteristics ensures a minimal impact on physical properties of the sampling space (draining effects, variable geometry factor etc.).

Other important feature is the possibility of a decontamination of chamber inner surfaces from radon progeny deposition.

Instrument applications

·         continuous measurement of soil-gas radon variations

·         studies of ground water level fluctuations

·         earthquake prediction

·         continuous record of radon concentration in samples taken from cracks and leakages in building constructions in contact with subsoil

·         continuous radon concentration monitoring in indoor environment with high content of radon (caves, mines, underground workplaces, basements etc.).

Notes:

For the field applications, the autonomous power generator unit and an appropriate protective shield against rainfall are necessary.

Particular limitation can be connected with the actual soil-gas permeability – in low permeable soils the system need not to work properly.

Technical parameters of the measuring system RM-3

Unique sampling technical arrangements
– a take-off probe special end fitting providing a defined continuous close circuit sampling
- effectively eliminates the ambient atmosphere influence on a long-term soil-gas sampling (temperature and pressure fields effects) and the close circuit with defined flow characteristics ensure a minimal impact on physical properties of a sampling space (draining effects, variable geometry factor etc.

Standard supply:

• Two airflow ionization chambers operating in a current mode (a sensitive detection volume 2litres)
• Control and operation unit – an electrometer device with a data logger (provides the detector operating voltage – 150V)
• Membrane pump
• Electronic flow meter with a memory storage
• Thoron (220Rn) suppression unit – a thoron additional signal is eliminated by its radioactive decay in a retarding piping system inserted in the sampling close circuit
• Take off probe end fitting