FALLOUT TRACK FROM THE ACCIDENT AT THE 4TH BLOCK OF THE CHERNOBYL NPPIN CERTAIN REGIONS OF THE LENINGRAD, NOVGOROD, AND BRYANSK DISTRICTS .1.

Results are presented from reconnaissance by automobile and foot of th e western regions of the Leningrad district, the northwestern regions of the Novgorod district, and the Novozybkovsk region of the Bryansk d istrict. Sites of soil contaminated by radionuclides are determined. T he main contaminants of the studied regions are Cs-137 and Cs-134. The activity ratio between these enables the contamination to be assigned a Chernobyl origin. Data are presented for the Cs-137 distribution am ong the soil fractions. The thinnest fraction that is the most active of the studied samples (Novye Bobovichi village, Bryansk district) con tains condensed and fuel fallout components. The vertical migration of Cs-137 in the various soil types is studied. The principal amount of Cs-137 (up to 80-90%) in the fall of 1992 in virgin parts was concentr ated in the upper soil layers (0-6 cm).