ABSTRACT
From the end of August - to the middle of September, 1986 radioactive samples were taken from the distance of 10–30 m over damaged block-4. Isotops Zr-95, Nb-95, Ru-103, Ru-106, Cs-134, Cs-137, Ce-141, Ce-144, Cm-242 and Pu-(238–242) were identified in all samples. In one sample from August 29 the concentration of gaseous form of 1–131 was 0,6 Bq/m3. The amount of ruthenium in gaseous form reached only 2–5% of amount of ruthenium in aerosols. Ba-140, La-140, I-133, I-135 and other short-lived radionuclides were absent in the samples. It proved that in the nuclear fuel which remained in the damaged block-4 fission chain reactions did not proceed. On the basis of measurements and calculations of radioactive matter exhausts from the damaged block-4 we proposed making the roof of “Sarcofag” without breaking free convection but with the filtration station in store for protection.
