Transbaikalian State University (Chita, Russia):

Sidorova G. P., Assistant Professor, Candidate of Engineering Sciences, e-mail: druja@inbox.ru

A part of coals from Urtuysk deposit has a high content of natural radionuclides (NRN). The enterprise, which fulfills this deposit was first confronted with the problem of their development.
The conditional density (content) of uranium in the coal is the basic criteria in the allocation of coal, which is contaminated with NRN. This density was defined by the integral gamma activity. According to these characteristics, all coals were divided into three grades.
I — the consumer. Pure coal with the uranium content by less than 0,001%, which corresponds to the number of its clark;
II — energy. Coal with a low contamination with NRN, in which the conditional uranium content is by 0,001–0,01%. This corresponds to the lower boundary of the off-balance ore, according to the uranium standards.
III — complex. Coal, which contains NRN with a conditional share of uranium by more than 0,01%. The ash and slag, which are formed during the combustion of this coal, have an activity, according to which, their usage is unacceptable for construction purposes.
The whole series of a scientific-research projects were conducted on all stages of the technological process: from the coal mining to calculation of the emission of ash and slag, during its burning. According to these series, the quality control system of Urtuysk deposit locals by the radiation-hygienic factors was developed and successfully used for nearly 20 years. The system is based on the concept of specific effective activity A_eff (Bq/kg), which was adopted from the practice of radiological assessment of the materials, which are used in construction.
The proposed system of coal quality control provides a representative rapid determination of a specific effective activity with the sufficient single shot accuracy for the radio-ecological requirements.

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