360 



The results of laboratory investigations demonstrate a direct relationship between 

 the concentrations of cesium- 137 and strontium-90 and the strength of the exposure dose 

 of gamma radiation (Figure 20). 



The nature of propagation of radioactivity into depth was investigated in three 

 bore holes 0.50-0.55 m deep; bore hole 3 - PR6.5 PK200, bore hole 4 - PR6.5 PKIOO, 

 and bore hole 5 - PR6.5 PKO. The breakdown: 0.00-0.05 m - soil and vegetation layer, 

 0.05-0.16 - gray sand (only bore hole No. 3), 0.05-0.55 (0.15-0.50 m in bore hole No. 3) - 

 yellow clay. Analyses of 6 samples from each bore hole indicate insignificant 

 permeability of the clay, nevertheless the process of radioactivity redistribution fi^om the 

 surface to the interface of thawing and frozen rock was observed (Figure 21). 



Analysis of the siuface waters in the trace outline for total beta activity performed 

 with the instrument RKB4-IeM at a differentiated counting rate, which makes it possible 

 to show cjualitari\'c wai ;r contamination (sample S112 - 24.6 s', S113 - 26.4 s'', S114 - 

 29.9 sS SH5 - 29.1 s\ drinking water - 18-20 s'*), indicates values below 1 x 10"*" Ci/1. 



The results of the analyses make it possible to conclude that radioactive 

 contamination in the trace is of a surface nature; most radionuclides were recorded in 

 the sofl vegetation layer, except for the area near the mouth of the explosion shaft and 

 the tomb, where radioactivity increases with depth. In the tomb zone on the surface at 

 140 Mr/hr, the total beta activity is 633.1x10''.'^ Ci/g, at a depth of 0.5 m, it increases to 

 540 Mr/hr and 1,193.6x10"'^ Ci/g. 



Surface water flows do not carry any significant concentrations of radionuclides. 

 Radionuclides enter the Markha River mainly due to mechanical runoff. 



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