Radioaktivnost atmosfere u Institutu za nuklearne nauke "Vinča" u periodu 1985-2015

Abstract

Institutu za nuklearne nauke "Vinča", dugi niz godina praćena je vremenska distribucija aktivnosti prirodnih i veštačkih radionuklida u prizemnom sloju atmosfere i padavinama. Aktivnosti prirodnih radionuklida 7Be i 210Pb, kao i veštačkog radionuklida 137Cs, određene su gamaspektrometrijskom metodom, dok je aktivnost 3H (može biti i prirodnog i veštačkog porekla) određena metodom tečne scintilacione spektrometrije. Ujedno je ispitivana i ukupna beta aktivnost, koja predstavlja indikatorsko merenje nivoa kontamincije atmosfere. U periodu ispitivanja, dogodila su se dva velika nuklearna akcidenta, 1986. u Černobilju i 2011. u Fukušimi, koja su doprinela povećanju koncentracije veštačkih radionuklida u životnoj sredini. U toku ovih događaja, praćena je dnevna promena koncentracije veštačkih radionuklida 137Cs, 134Cs i 131I u atmosferi. Na osnovu rezultata dugogodišnjih merenja, određene su srednje mesečne koncentracije aktivnosti, pokretne sredine kao i mesečni i kvartalni indeksi za navedene radionuklide, iz kojih su uočeni sezonski efekti. Maksimalne aktivnosti 7Be i 3H dostižu u letnjem, a minimalne u zimskom periodu. U slučaju 210Pb, aktivnosti su bile maksimalne u jesenjim, a minimalne u prolećnim mesecima. Za radionuklid 137Cs, maksimalne aktivnosti su dobijene u mesecima prelaska proleća u leto i jeseni u zimu (manje izražen maksimum).

A long term measurements of temporal distribution of naturally occurring and artificial radionuclides in the ground level air are conducted for many years in the Institute for Nuclear Sciences "Vinča". Activity of naturally occurring radionuclides 7Be i 210Pb and artificial radionuclide 137Cs is determined via gamma spectrometry and activity of 3H in precipitation (which can be both naturally occurring and artificial) is determined using liquid scintilation spectrometry. Along these, gross alpha and beta activity measurements are also conducted. These measurements represent the indicative of atmospheric contamination. During the period of this monitoring, two major nuclear accidents have taken place – the one in Chernobyl 1986 and the accident in Fukushima 2011, that have contributed to the rise in the activity concentration of the artificial radionuclides 137Cs, 134Cs , 131I and 3H in the environment. Based on the results of these long term measurements, average monthly activities, monthly and seasonal indices for the mentioned radionuclides were determined and seasonal periodical effects were noticed. Maximum values of 7Be and 3H were noticed in summer and minimum values were noticed in the winter. In case of 210Pb, activity concentration reached its maximum in autumn and minimum in spring. For 137Cs, maximal values were detected in the months between the season of spring and summer and autumn to winter (less pronounced maximum).