Section III Applications of radioisotopes, nuclear instrumentation For industry and medicine, radiation safety problems

Alpha-Guard device was used along with the track detectors, and the calibration factor for the track detector device was evaluated The result of our measurements have shown that in air of rooms of multi-storey houses a radon concentration level in the first (1-4) floors was in the range of 33 - 97 Bq/m\ and in the higher (5 - 9) floors was in the range of 28-55 Bq/m3 The higher values of radon level from 120 up to 270 Bq/m3 were observed in air of separate one- storey houses This can be explained by permeation of a radon gas through the slots in the floor and accumulation of it due to poor ventilation

RADIOCHEMICAL NEUTRON ACTIVATION ANALYSIS OF MANGANESE -

Sadikov I.I., Zinovev V.G. UZ0302067 Institute of Niiclecu Physics, Uzbekistan Academy of Science, Tashkent, Uzbekistan

The triple compound MnJHgi_xTe is a worth-while material to produce infra-red detectors Its properties depend on the contents of impurity elements Therefore, analytical control of the MnxHgi_\Te is required Techniques of neutron-activation analysis (NAA) of Te, Hg, CdxHgi.xTe, PbSnTe materials have been developed recently However no papers on the NAA of MnJHgi xTe have been found This work is devoted to the development of a radiochemical NAA technique for MnxHgi.sTe compound, with ion exchange chromatographic separation of matrix radionuclides and impurities in the system of Dowex-lx8-HCl A number of long-lived radionuclides of manganese, , mercury as well as radionuclides of iodine and antimony are formed during the irradiation of Mn\Hgi xTe samples by nuclear reactor neutrons The high specific radioactivity of these tadionuchdes makes impossible to utilize instrumental NAA Therefore the technique, developed by us, provides radiochemical separation of matrix and impurity radionuchdes The experiments have shown, that the separation factors of the impurity radionuchdes from matrix should be no less than 107 for tellurium, 108 for iodine and fO9 for mercury The half-life of ?6Mn (2 58 h) allows one to decrease its activity by cooling down of irradiated sample for 2-3 days Radioactivity of 54Mn is negligible due to small activation cross-section 35 54 of the Mn (n, 2n) Mn reaction Besides, total amount of manganese in MnKHgi.xTe is rather small, x is normally to be about 0 1 For selective separation of tellurium, mercury and antimony radionuclides we used an ion exchange chromatographic system Dowex-1x8-4 M HC1 For optimization of the chromatographic column sizes and volume of eluates, the distribution of matrix along the column and elution curve of impurities have been measured The experiments have shown, that the separation factors for mercury, tellurium and antimonies thus exceed 109 The basic amount of iodine leaves during evaporation time of a solution of the analyzed sample Residual iodine, and also n'l formed at beta fission of niTe during chromatography separation almost completely retained in the chromatographic column Thus, this chromatogiaphic system allows simultaneous separation of a number of elements from matrix radionuchdes of Te, Hg and Sb and also I at radiochemical NAA of

Mnjigi xTe On the base of the carried out studies the technique of radiochemical NAA of MnxHgi. 4 8 xTe capable of determining moie than 20 impurities with detection limit of n 10" -n 10" mass % has been developed

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