369 



Laboratory of the Department of Radiation Hygiene, 

 Yakut Republic Sanitation and Epidemiology Station 



RESULTS 



of Radiometric Analysis of Soil Samples 



firom the Mirny Rayon in July 1990 



The total beta activity of the soil samples was determined on the UMF-ISOO unit 

 in accordance with procedural instructions approved by deputy chief sanitary physician of 

 the Russian Federation N.S. Titkov on November 14, 1975. Total beta activity of the 

 soil was measured with the aid of a kit including the STS-5 counter and a loose sample 

 container. Since the beta activity of soil is determined approximately 70% by potassium- 

 40 and 30% by the isotopes of the uranium and thorium series, UMF-1500 was 

 calibrated against potassium chloride, because, the average energy of the beta particles of 

 the uranium and thorium series measured by the counter STS-5 is practically equal to 

 that of potassium-40. The specific activity of potassium chloride is S-STXlO'^Ci/g. 



The total alpha activity was measured on the BDA um't using the procedure 

 "Determination of Total Alpha Activity of Soil" approved by the deputy chief of the 

 Main Administration of Research Institutions and Scientific Research Coordination, N^ 

 Demidov on August 25, 1976, and developed.by the Leningrad Research Institute of 

 Radiation Hygiene of the Ministry of Public Health of the Russian Federation. BDA 

 was cah'brated against a sofl "reference" containing 6.3X10"*" curie of thorium per gram 

 of soiL 



The total alpha and beta activity comes from 14 alpha emitters and 6 beta 

 emitters of the uranium and thorium series and potassium-40. With their average 

 concentrations in soU of U = 2.4X10^ Ci/g, Th - SXIO"* Ci/g, and K-40 = ZXIO'^ Ci/g, 

 the total alpha and beta activities are almost equal: 



Za = 8pa(U) + 6paCni) = 6.4 X 10"" + 53 X 10"" Ci/1 = 11.7 X 10"" Ci/1 



S^ = 3p/S(U) + 3p^(Th) +p^(K*^ = (2.4 X lO" + 2.6 X lO"" + 16.2 X 10"" Ci/g 

 = 21.2 X 10" Ci/g 



hence 2a = 0J5. 



When there is little uranium and thorium in soil, this ratio is significantly lower. 

 At present, there are no maximum permissible levels for sofl. 



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