Specific features of radioactive aerosols in subreactor rooms of the shelter object of Chernobyl NPP

Data on the radionuclide composition, volume activity, and dispersity of aerosols taken in 2010–2014 using Petryanov’s filters in rooms 012/7, 012/15, and 210/7 of the Shelter object, into which the lava-like fuel-containing materials (LFCMs) flew after the accident, are presented. In room 012/7, the volume activities of aerosols carrying the Chernobyl accident products are higher by an order of magnitude than those in rooms 012/15 and 210/7. In all the rooms, the carriers of the radioactive products of the accident are, as a rule, aerosols with the activity median aerodynamic diameter larger than 1 µm. This value suggests the dispersion origin of the aerosols. In room 012/7, the aerosols are larger than in the other two rooms. The identity of the radionuclide composition of aerosols and LFCMs in room 012/7 shows that aerosols arise from the degradation of the lava. Considerable difference in the radionuclide compositions of aerosols and LFCMs in rooms 012/15 and 210/7 shows that the lava degradation in these rooms is less intense and that the aerosol generation from the lava surface does not influence the radionuclide composition of aerosols.