Part of the continuous nationwide monitoring of radionuclides in Finland. STUK is responsible for monitoring of radioactivities in atmosphere. STUK operates a network of eight aerosol samplers from which three are located in Finnish, Lapland at Rovaniemi, Sodankylä and Ivalo. The sampling is done either weekly or bi-weekly. Gammaspectroscopic measurements are done in the laboratory in Rovaniemi. The lowest activities are detected at microBq/m3 level.
Sampling is performed using specially designed samplers, which filtrates large amount of air. Airborne radioactive particles are deposited on glassfibre filters whereas charcoal filters are used for gaseous species such as iodine. The samplers are manually operated. Small quantities of radioactive material may be detected using sophisticated laboratory analyses. In the laboratory the glassfibre filters are compressed, substituted into plastic beakers and analysed with a high-resolution gamma-ray spectrometer. Nuclide specific minimum detectable concentrations (micro Bq/m3) depends on filtrated air volume, activity of background nuclides in the sample, measuring time and decay time before the measurement.
Rovaniemi, Korkalovaara (flow rate 900 m3/h) Sodankylä, Meteorological Observatory (flow rate 150 m3/h) Ivalo (flow rate 150 m3/h) The Rovaniemi airfilter system is provided with detector on-line, which can be used in the early warning system.
Glassfibre airfilters either in STUK/Rovaniemi or STUK/Helsinki since 1989.
Filters compressed into “pucks” for measurement or they are cut into roughly 12x12cm pieces. The filters are placed into plastic jars and stored in a metal canisters.
Intercomparison measurements e.g. NPL proficiency test exercises.
Routinely the information is reported to EURDEP and CBSS databases. Abnormal findings are reported to other international organizations.
Radionuclides in precipitation
Addition to the previous comments: The aerosol sampler located from 1993 in Salla, Karhutunturi, was transferred in summer 1999 to Sodankylä. Now the aerosol and precipitation samplers are placed in the same location.