377 



Markha River, (1 km upstream from the "Kraton-3" site of discharge). The 

 radiochemical analysis showed the following: a sample from the Ulakhan-Botuobuy 

 River: strontium-90, 1.5X10"'^ Ci/1; cesium-137, less than 0.5X10'^ Ci/1; uranium-238, 

 0.3X10" Ci/1; radium-226, 0.3X10'^ Ci/1; a sample from the Taas-Yuryakh River: 

 strontium-90, l.eXlO'^ Ci/1; cesium-137, less than O.SXIO'^ Ci/1; uranium-238, 0.6X10'^ 

 Ci/1; radium-226, 0.2X10-" Ci/1/. 



"Kristall": two water samples were taken for the total beta activity, one from the 

 crater left by the explosion, the other from the Ulakhan-Bysyttakh River. Analysis 

 showed less than IXIO*" Ci/L 



"Kraton-3": 16 samples were taken for total beta activity, 2 for radiochemical 

 analysis, and 2 for analysis using the procedure of ion-exchzinge resins for strontium-90. 

 The total beta-activity of all samples was below 1X10'"* Ci/1. Radiochemical analysis of 

 two samples from the Markha River collected at the mouth of the brook at the site of 

 the explosion and 50 m downstream showed strontium-90, 2.5X10"'^ and OJXIO'" Ci/1; 

 cesium, less than 0.5X10"" Ci/1; uranium-238, 0.3X10" and 0.4X10" Ci/1; radium-226, 

 0.2X10"" Ci/1, in both samples. According to the analysis results of two samples taken 

 &t>m the Markha River 1 km upstream and 20 m downstream from the mouth of the 

 same brook, the content of strontium-90 was 3.2 and 8.5 Bq/m^ 



The results obtained from field studies and laboratory investigations make it 

 possible to give recommendations for the future orientation of studies of the radiation 

 situation in the territory of the republic, and for the design and conduct of similar 

 operations in new areas. 



1. A more detailed dosimetric study should be made of areas containing 

 radioactive contamination spots in order to develop specific recommendations and 

 proposals on carrying out decontamination, recultivation, or the recording of 

 radioactivity. 



2. The areas of airborne gamma-spectrometric survey should be expanded for the 

 purpose of foDowing the trace of the radioactive cloud (sites "Kristall" and "Kraton-3") 

 from the site of discharge to the administrative boundaries of the Republic, on the basis 

 of data provided by the Yakut Hydrometeorological Service. 



3. All underground nuclear explosions should be investigated using the technique 

 that has been developed. The investigations should include: an advance airborne 

 gamma-spectrometric survey on the scale of 1:25,000 in a 10-km radius, regardless of the 

 results of aerial operations, a radiometric survey of the site of the explosion shaft 

 opening over an area of 1.0x1.0 km with dosimetric measurements over a grid of 20x20m 

 with topographic layout and pegs set out, spectrometric measurements, testing sofl and 

 vegetation on technogenically disturbed and undisturbed land. These operations will 

 make it possible in the future to ensure time control of the radiation situation. 



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