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 11 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.
After radiochemical separation, additional radionuclides are determined in the quarterly combined filter samples from MSAC in Prague: ⁹⁰Sr is measured by beta radiation and ²³⁸Pu with ^239,240Pu by alpha spectrometry. Additionally, air samples are continuously taken at MSAC Prague for determination of ¹⁴C and ³H radionuclides by liquid scintillation counting.

Charts:
Monthly mean values of activity concentration of ¹³⁷Cs, ⁷Be and ²¹⁰Pb in airborne aerosol. 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