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The atmospheric contamination measurement sites

Monitoring of radionuclides in air is performed at the Monitoring Sites of Air Contamination (MSAC) with the aerosol sampling equipment that continually sample the aerial mass through an aerosol filter with a flow rate in range between 40 and 900 cubic meters per hour.

MSAC network is divided to territorial and local networks. Territorial network consists of 10 MSAC (and 6 monitoring sites in the vicinity of the NPP Dukovany and 7 in the vicinity of the NPP Temelin) run by regional centres of  SÚJB, SÚRO and ČHMÚ.

MSAC cooperates with EWN. Their primary aim is to indicate all changes in concentrations of man-made radionuclides in the air mass and to monitor their long-term time course. Measured values serve as a basis  for  estimation of  the exposition of  population from inhalation.

Aerosol filters are changed weekly. They are subsequently analysed by means of  semiconductor gamma spectrometry. 137Cs, 7Be and 210Pb are currently identified. 137Cs is artificial, 7Be has a cosmic origin and 210Pb is a final daughter member of 238U decay series. Natural radionuclides are analysed with purpose of quality control of the laboratories. Current activity concentration of 137Cs has not exceed few μBq/m3 last years. 137Cs comes from global atmospheric fallout. It has  partly originated from nuclear weapons test, partly from Chernobyl NPP accident.
Radiochemical analysis of 90Sr (Beta spectrometry), and 238, 239, 240Pu (alpha spectrometry) are performed quarterly. 85Kr and 14C activity concentrations are also being determined. 85Kr comes from fuel reprocessing industry, 14C is partly natural (interaction of cosmic neutrons with atmospheric nitrogen), partly artificial produced by nuclear weapon tests and nuclear industry (nitrogen activation in reactors).

Charts:
Monthly mean values of activity concentration of 137Cs, 7Be and 210Pb in airborne aerosol and 85Kr in the atmosphere. These data have  been measured since the year 1986. Long-lasting decrease of 137Cs activities is obvious. Seasonal variations of 7Be activities are also visible.
Last year average weekly measured activity concentrations of 137Cs, 131I, 7Be and 210Pb