In June 1992, BAI - Brussels obtained the commission to set up the "Telerad" network monitoring the radioactivity in the environment in Belgium.

Telerad is a network for routine measurements in case of accidents occurring in one of the nuclear sites located in Belgium or abroad.  It therefore includes measurements of ambient radioactivity in air and water as well as meteorological data.

The Telerad network automatically measures the following radiological variables :

          - local g-dose rate (183 measuring stations)

          - air-borne a/b-activity (7 measuring stations)

          - air-borne iodine activity (7 measuring stations)

          - air-borne g-activity (3 measuring stations)

          - g-activity in water (6 measuring stations)

The data is transmitted to the central station in Brussels via X-25.  Telerad is designed to monitor large areas ; however, the nuclear facilities, such as Tihange, Doel, Mol and others, feature a ring-shaped structure.  In this case the data is also transmitted to the respective nuclear power plant.

Telerad is a modern large-scale measuring network, combining highly sensitive measuring technique and complete data communication (automatic spectrum transfer).

Local g-dose rate measurement

183 measuring stations are employed to measure the local g-dose rate.  Each measuring station consists of 2 redundant low dose probes (type : LB 6360) and one high dose probe (type : LB 6361).

Highly sensitive proportional counter tubes, integrated into an intelligent "at-site" electronics, serve as low dose detectors.  The use of proportional counter tubes permits very sensitive measurements.  The measuring ranges of proportional counter tubes ranging from several nSv/h to several mSv/h overlap with the range of the high dose Geiger-Müller counter tube (up to several Sv/h).

All measuring stations are equipped with rain sensors to rule out misinterpretations following an increase of the local dose rate due to natural causes, for example, after rain showers or thunderstorms.  58 of the 183 measuring stations are installed in rings around nuclear-technical facilities.  125 measuring stations are employed in the large-scale measuring network (20-km distance between the individual stations).

The data provided by the large-area probes and the local ring probes are transmitted to the nuclear facilities and the central station in Brussels.

In addition, the wind direction and the wind speed are measured at 9 locations of the large-area measuring networks.

a/b-activity and iodine activity measurement

Step filter systems type BAI 9100D are used for the measurement of air-borne a/b-activity concentrations.  These moving filter systems allow automatic operation periods up to 6 months.

At four measuring stations the a/b-moving filter systems have been supplemented each by a continuous iodine measuring system.  The measurement of radio-iodine is carried out using common plastic cartridges.  The iodine measuring system is a further development of the moving filter system BAI 9100DGI ; due to its iodine cartridge changing mechanism it permits long operation periods and features a high sensitivity.

a/b, g and iodine activity measurement

At three other measuring stations the set-up described above is supplemented by a g-spectrometric nuclide analysis.

The moving filter system BAI 9100DG used for this purpose features a HP-germanium detector the fully automatic g-spectroscopy installed in the a/b-system.  g-spectroscopy which was especially designed for environmental monitoring, the latest in hardware and and software make up a highly sensitive measuring system that is capable of automatic analysing.  The software meets the requirements of the Institute for Atmospheric Radioactivity (IAR) in Freiburg, Germany.

The major advantage of the BAI 9100DG is that spectra, in addition to the measured values, can be remotely transmitted as well, so that a team of experts in the central station may carry out a detailed analysis of a spectrum, if necessary.

Water measurement
BAI 9125 monitors are employed for the measurement of g-emitting nuclides in water at 6 locations.  These water-measuring systems are a reasonable addition to the air monitoring stations, particularly in a country like Belgium with its many waterways.

On-line measuring results

		Customer defined applications

		Belgian home page