Radiation Monitoring Network
Information on radiation required by the system that protects the population and environment from radioactive materials and ionizing radiation (radiation protection) comes from several sources, among them the Radiation Monitoring Network of the Czech Republic (RMN).
The first part of RMN was put into operation as soon as 1986 after the Chernobyl accident. The present function and structure of RMN is set down in the SONS Decree No. 27/2006 Sb.
The task of RMN is to monitor spatial and temporal distribution of the activity of radionuclides and doses of ionizing radiation on the national territory. Under normal radiation situation, the purpose of the monitoring is to establish long-term trends and identify in time any variations from these trends. In extraordinary situations, the task of RMN is to assess the radiation situation on the national territory and provide background information for deciding on countermeasures to protect the population. RMN is focused, in particular, on the following artificial radionuclides: 3H, 137Cs, 90Sr, 239+240Pu and 85Kr in the atmosphere, 137Cs, 90Sr and 3H in food, and 137Cs in the human body. Since last two years, 14C (which is of both artificial and natural origin) has been also monitored.
RMN operates under the control of SONS. Within this frame, NRPI ensures a number of RMN functions, in particular:
• Providing methodological guidance to the individual RMN sections, including the development and verification of new measurement methods.
• Preparation of the monitoring plan; development, permanent review and updating of the sampling and measurement procedures (in 2003, a package of 25 such methodologies was produced by NRPI and handed over to SONS).
• Collection of data for the RMN Information System central database, verification of data quality and analysis of data for the whole national territory.
• Organising the comparison measurements and their evaluation.
• Operation of the RMN central laboratory that co-ordinates the measurements on samples taken by individual laboratory and mobile groups. The laboratory has a broad-scale sampling and analyses program of its own; it also ensures special measurements and analyses that cannot be provided by other organizations, including the .
• Assisting other laboratories when their measuring capabilities are deficient.
• Providing background documentation for annual reports on radiation situation on the national territory, compiling and publishing reports.
• Continuously updating the information on radiation situation shown on the internet.
• Permanent emergency service for the case of a radiation emergency.
• Providing support to the SONS Emergency Co-ordination Centre to ensure permanent emergency preparedness, participation of the NRPI staff in the SONS Crisis Team, ensuring operation of the RMN Information System backup central desk.
RMN consists of several mutually co-operating partial networks and NRPI is playing an important role in most of them. This refers to the Early Warning Network (SVZ), the thermoluminiscence dosimeter (TLD) network, atmospheric contamination measurement sites (MMKO), laboratory teams, the central laboratory, and ground and airborne mobile groups. The information system is also included in RMN as its integral part. Activities of individual RMN components are co-ordinated via the monitoring plan that provides binding instructions to each component of the network concerning the places, time, frequency and method of measurement or sampling, as well as the methods of sample processing, measurement and assessment, and manner and frequency of reporting. There are two different modes of operation - under normal radiation situation and during radiation emergencies.
The following components are active under normal radiation situation:
• with 47 measurement sites spread over the national territory that are continuously measuring the dose-equivalent rate (PDE) in 10-minutes integration intervals.
• with the total of 184 measuring sites evenly spread over the national territory. They are equipped with thermoluminiscent dosimeters that are exchanged every three months. The results are evaluated as the equivalent dose during the measuring period. Similarly are the TLD dosimeters used in TLD local networks with 92 measuring sites in the surroundings of nuclear power stations.
• with the aerosol sampling equipment that continually sample the aerial mass through an aerosol filter, which is analysed once a week in a laboratory by semi-conductor gamma-spectrometry.
• The laboratory groups carrying out spectrometric or radio-chemical analyses of the radionuclide contents in samples taken from the environment. Aerosol filters are analysed in one-week intervals, fallouts once a month, milk and meat samples every three months, drinking water once a year, and samples of cereals, potatoes, fruits, vegetables and mushrooms after the harvest or picking.
• The central NRPI laboratory that carries out, besides standard analyses, special determinations in selected samples, especially for 90Sr, 239, 240Pu, 3H a 14C. Besides this, analysis of urine samples from a group of individuals representing the whole population of the CR is carried out once a year. Once a year, the retention of 137Cs in a selected group of individuals is also determined in vivo on the whole body counter in the central laboratory, with the help of semiconductor spectrometry.
• The mobile groups that are mapping the radiation situation based on ground and aerial monitoring of the dose rate and surface contamination. They also ensure the distribution of TL-dosimeters, qualitative and quantitative field evaluation of radionuclide activities (in-situ spectrometry), sampling and search for lost sources of ionising radiation. NRPI operates two such specially equipped groups. In co-operation with the Czech Army, NRPI plays a decisive role in ensuring activities of an airborne group that covers the whole national territory.
Current information provided by RMN is continually published on the NRPI internet site (www.suro.cz) together with other results. Once a year, the Report on Radiation Situation on the Territory of the Czech Republic is published on www.sujb.cz.
Under extraordinary radiation situation, the control of the RMN network is taken over by the SONS crisis team to respond to specific features of the situation.