Aerosol emissions from the destroyed power-generating unit of the Chernobyl nuclear power plant in 1986 and 2003–2005

Abstract

The results of measurements of the volume activity and dispersity of aerosol carriers of β-emitting radionuclides during the acute phase of the accident and 20 years later are presented. It is determined that in August–October 1986, when samples were taken 10–50 m from the surface of the destroyed reactor, the concentration was about 1 kBq/m3, which is 100–1000 times higher than the value recorded in July–August of the same year from an aircraft flying at altitudes 200–1000 m. Thus, already in mid-summer 1986, because of the decrease in temperature, the aerosol emissions did not reach the survey altitude of the aircraft. Therefore, the sampling performed from the aircraft did not permit a quantitative assessment of the emissions of radioactive materials during this period of time. In 2003–2005, the total β activity was 10–100 times less than in fall 1986, because of the radioactive decay of 95Zr, 95Nb, 103,106Ru, 134Cs, 141,144Ce, and other radionuclides. Since the 137Cs concentration decreased negligibly, it seems that the roof constructed in 1986 above the Shelter was of little use.