Monitoring radioactivity in the environment
The radioactivity in the environment that is a result of human activity must be monitored. The radiation dose caused by exposure to ionising radiation from radioactive substances is subject to regulations. Ionising radiation emitted from natural and artificial radionuclides collides with substances that surround the source.
Substances can absorb radiation. Radiation gives off energy to the radiated substance through ionisation or excitation of atoms. Therefore, it can be said that a body has received a certain radiation dose. Radioactive substances in the environment directly irradiate people, and they also enter human body through breathing and through food and water consumption.
This absorbed dose cannot be measured directly; however, it can be calculated using environmental radioactivity data. We receive this data from radioactivity monitoring programmes.
Environmental radioactivity monitoring programmes
In Western European countries, monitoring of radioactivity in the environment already began in the times of intensive nuclear aerial tests, and it was regularly introduced in the territory of present-day Slovenia in 1961.
Monitoring of radioactivity in the environment is not intended for measuring natural radioactivity but rather for monitoring the radioactivity that spread due to nuclear tests and nuclear accidents in the past or will potentially in the future. Therefore, important globally dispersed radionuclides or important radionuclides that are locally released into the environment by nuclear or radiation facilities are measured.
Scope of environmental radioactivity monitoring
Radioactivity monitoring generally includes measurements of radioactive releases from nuclear and radiation facilities and measurements of radioactivity in the living environment. In the scope of the environmental radioactivity monitoring programme, radioactivity of air, soil, precipitation and surface waters, as well as of drinking water, food and animal feed is measured.
In the environmental radioactivity monitoring programme, sampling locations, sampling strategy and frequency, measurement techniques, radionuclides, and measuring frequency are determined for every type of sample.
The monitoring programme of radioactivity in the wider territory of Slovenia covers the country's distinct regions that differ in the level of contamination with long-lived radionuclides caesium Cs-137 and strontium Sr-90 (Central, Alpine and Pannonian Slovenia). The environmental monitoring programme of nuclear and radiation facilities is geographically restricted to a few kilometres around each facility. The content of the programme is tailored to the types of radionuclides, their release into the environment, their transmission routes and their relevance in terms of the radiation exposure level of the population.
Purpose of monitoring radioactivity in the environment
Monitoring radioactivity in the environment allows real-time monitoring of the existing radioactivity in the environment, the determination of radioactive contamination levels and calculating public exposure due to the radioactive contamination of the environment.
Radioactive contamination in the environment changes over time, which is important to monitor the trends of radioactivity in the environment. On the one hand, the level of existing contamination has been decreasing due to radioactive decay, migration of radionuclides into the deep layers of soil and run-off from surfaces. On the other hand, however, the level of radioactive contamination can temporarily rise due to unforeseen events (such as the Cs-137 source meltdown in Spain in 1998 or the release of I-131 from the Paks nuclear power plant in Hungary in 2003).
Radioactivity monitoring, especially the part of the programme covering the real-time measuring of dose rate in the national network throughout the entire territory of Slovenia, enables us to detect an increase in the levels of radioactivity or radiation in the environment in time.
Radiation Exposure of the Population in Slovenia
Apart for the calculation of the state of environmental radioactivity and its levels, the data provided by the radioactivity monitoring is also used for calculating the exposure of the population. Usually, the dose is calculated for an adult from the most exposed population group who lives near a facility that releases radioactive substances into the environment.
First, the annual intake is determined from the data on radionuclide concentration in the air, and then the dose received from inhalation is calculated. The dose received from radionuclides in the drinking water is calculated in a similar manner. The dose received through ingesting food is determined from the data on radionuclide content in food and on the annual consumption of individual ingredients. The dose of external radiation is determined from the data on environmental radiation levels. The total effective dose for an individual is calculated by adding all these doses together. The total sum must not surpass the annual dose limit value that is laid down in the relevant regulations or the annual dose limit that was approved by the administrative authority.
The role of the Slovenian Nuclear Safety Administration in ensuring monitoring radioactivity in the environment
The competent administrative authority for monitoring radioactivity in the environment is the Nuclear Safety Administration, which draws up regulations on radioactivity monitoring, establishes a national radioactivity monitoring programme and approves the radioactivity monitoring programme for the surroundings of nuclear and radiation facilities, it also authorises professional and research organisations for radioactivity monitoring, approves the emissions monitoring programme, regularly monitors radioactive releases from nuclear and radiation facilities, reports to the Government of the Republic of the Republic of Slovenia and to the National Assembly of the Republic of Slovenia on environmental radioactivity and radiation and informs the public through annual reports. In addition, it also regularly communicates the radioactivity data to the European Joint Research Centre in Ispra, Italy and to neighbouring countries.