| 摘要 |
radiation control. SUBSTANCE: sample is attested for specific radionuclide activities as follows: U238-34,7±3,5, -34.7+/-3.5, U234-37,3±3,7, -37.3+/-3.7, Th232-43±4,3, - 43+/-4.3, Th230-50±7,5, -50+/-7.5, Th228-44±4,4, -44+/-4.4, Ra226-135±13,5, -135+/-13.5, Ra228-36,4±5,5, -36.4+/-5.5, Ra224-48,8±7,3, Pb-36±3,6, Po-36±3,6, -48.8+/-7.3, Pb 36+/-3.6, Po 36+/-3.6, K40-460±32, -460+/-32, Pu239+40-10±1,0, - 10+/-1.0, Pu238 < 0,5, <0.5, Am241-12±1,8, - 12+/-1.8, Cs137-30±2,1, - 30+/-2.1, Sr90-18±2,7, - 18+/-2.7, Σalpha-590±88,5, - 590+/-88.5, Σbeta-900±135 - 900+/-135. Also attested are summary alpha- and beta- emitting radionuclides for analytical 1-g weight representative of all volume of standard sample. To prepare standard samples, natural soil (13- 15.6 kg) is dried in the open air, disintegrated to particle size at most 0.074 mm. Sample is placed in polyethylene container, stirred to avoid segregation. Inert organic liquid (10-11.5 l) is added for 12-15 min. Sample is further stirred, neutral radionuclide solution is added, mixture is settled, and liquid phase decanted. Precipitate is dried at room temperature at stirring. Sample is broken to particle size at most 0.074 mm and stirred to give air-dry material of sample with homogeneous distribution of radionuclides. Deviations from mean values of measured counting velocities 7-10% are caused by measurement error. EFFECT: increased measurement accuracy. 2 cl, 9 tbl
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