Early Warning Network
In the event of a nuclear accident or any other accident involving a radiation source, where a large quantity of radioactive substances would be released into the environment resulting in significant radiological consequences, it is necessary to provide instant information on radiation levels and radioactivity in the environment. Soon after the Chernobyl disaster, Slovenia set up an automatic measuring system for the real-time detection of elevated radioactivity levels in the environment.
The early warning network in Slovenia includes the national measuring system managed by the Nuclear Safety Administration and, to a lesser extent, the system at the Krško Nuclear Power Station. There are 72 monitoring stations in the Early Warning Network. They send the measured data to the central computer at the Slovenian Nuclear Safety Administration.
The Nuclear Safety Administration is in charge of continuous data analysis, while a 24/7 standby system is also in place in case the radiation levels anywhere in the country exceed the alerming levels. The Nuclear Safety Administration is also the consulting body of the National Civil Protection Headquarters in the case of nuclear or radiation emergencies.
The Early Warning Network consists mainly of automatic dose rate meters (72 in total), and three airborne radioactivity meters and two radioactivity deposition meters (measuring deposition in the ground). Dose rate meters are type MFM 202 and MFM 203 dose rate meters made by the Slovenian company AMES.
The dose rate has two probes (radiation detectors), which have integrated Geiger-Müller tubes (high-sensitive and low-sensitive). The dose rate meter measures the quantity H*(10) and it is calibrated to the Cs-137 isotope.
In normal conditions, the radiation is measured by the high-sensitive probe. The meter's reading reveals the radiation level caused by the natural radioactivity of Earth and cosmic rays. In Slovenia, those levels fluctuate between 0.08–0.12 μSv/h. In the event of the Chernobyl disaster, the meters in Central Slovenia would have displayed values 20 times the normal level (1.5–2.0 μSv/h) during the first days. In heavy rain, the meters record an increase in dose rate lasting for several hours and reaching the maximum value of 2 times the normal level.
Every half hour, the metres send data to the central computer.
In Slovenia, airborne radioactivity is measured in three locations, namely, in Ljubljana, Krško (NEK) and Drnovo near Krško.
The concentration levels of radionuclides expressed in Bq/m3 are determined with gamma spectrometry, and the results are sent out every six hours or daily.
Radioactivity in the soil (depositions on the ground) is measured in Brinje near Ljubljana and in Drnovo.
The results in Bq/m2 are transmitted every six hours.
The measured data of radioactivity in the environment are available to administrative authorities, persons conducting measurements and, online, to the general public. They are also available to the administrative authorities of neighbouring countries with an agreement with Slovenia and to the Joint Research Centre in Ispra, Italy.