AN INNOVATIVE RADON CALIBRATION CHAMBER
The RADONSTAR calibration laboratory is designed in compliance with the requirements of the IEC 61577-4: 2009 technical standard “Radiation protection instrumentation – radon and radon decay product measuring instruments – Part 4: Equipment for the production of reference atmospheres containing radon isotopes and their decay products (STAR).” IEC 61577-4:2009 concerns the System for Test Atmospheres with Radon (STAR). The name RADON STAR comes from this acronym.
RADONSTAR uses an innovative method called HYBRID MODE. The hybrid mode is a new operation method benefiting from the advantages of standard configurations without their most significant limitations. This operation mode makes controlling the variation of activity concentration of radon-222 inside the calibration chamber more practicable. RADONSTAR also uses an innovative method to exhaust the radon gas faster, more efficiently, and more securely. The improvements applied in the RADONSTAR calibration laboratory were invented and developed by Dr. Reza Hosseini and Eng. Gianluca Troiano, for which two patent applications have been submitted at the Italian and European levels.
THE RADONSTAR CALIBRATION LABORATORY CONSISTS OF THE FOLLOWING:
-Laboratory
The RADONSTAR laboratory is a division of Niton srl. Niton srl is also equipped with a CR-39 laboratory and is considered one of Italy’s most important companies in providing passive radon detectors. Furthermore, Niton srl manages RadonMarket, the biggest European provider of radon testing and mitigation supplies.
-Control system
The control system consists of a control panel, solenoid valves, pumps, and digital switches. A microcontroller is used to automatically control the electronics in order to perform each calibration program. The microcontroller is installed on a personalized PCB and pre-programmed in the C language for several calibration test types. It is possible to update the programs by connecting the control panel to a computer via a USB cable. The control panel is equipped with an LCD and buttons to monitor and control each calibration program by the laboratory technicians. Thanks to this system, it is possible to start a calibration test, keep the activity concentration of radon constant, and increase it or discharge it completely automatically. The system was engineered and developed internally at Niton srl exclusively for the RADONSTAR laboratory by Dr. Reza Hosseini.
-Radon source
A Eurostandard certified radon source is used to generate a constant activity of radon-222 concentration.
-Reference instrument
The metrological traceability is guaranteed by using a DURRIDGE RAD7 real-time radon monitor as a reference instrument. The reference instrument is calibrated at least once a year in European institutes certified under ISO 17025. 
-Environmental parameter measurement Instruments
The environmental parameters of temperature, relative humidity, atmospheric pressure, and ambient gamma dose rate are constantly monitored both inside the calibration chamber and externally. The values recorded during the calibration tests are stored digitally and reported in the Calibration Reports.
-Zero-radon reference atmosphere
For the purpose of CRMs background checks and as a part of each calibration session, a special chamber is used in which the instruments are exposed to a nitrogen atmosphere.
-Exhaust system
An innovative exhaust system is designed and used to exhaust the radon gas faster and more securely. The exhaust system complies with the standard requirements and is controlled by the RADONSTAR control system completely automatically.
-Radon reference atmosphere
For the purpose of calibration measurement devices, a sealed radon-222 reference atmosphere is created inside a climatic chamber. Using a climatic chamber instead of a typical container makes it possible to control, monitor, and manipulate the environmental parameters during tests. At the moment, RADONSTAR controls the temperature and the average activity concentration of radon-222 and constantly monitors the humidity, relative pressure, and ambient gamma dose rate.
