AEROSOL EMISSIONS FROM THE DESTROYED POWER-GENERATING UNIT OF THE CHERNOBYL NUCLEAR POWER PLANT IN 1986 AND 2003-2005

摘要

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/m~3, 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 ~(95)Zr, ~(95)Nb, ~(103,106)Ru, ~(134)Cs, ~(141,144)Ce, and other radionuclides. Since the ~(137)Cs concentration decreased negligibly, it seems that the roof constructed in 1986 above the Shelter was of little use.