COMBUSTION TEST IN STUDY ON RADIOACTIVE ENVIRONMENT EVALUATION OF COAL

Samples from 11 coal mines in Kangping, Shenbei, Dongliang, Liaoyang, Fuxin, Hunjiang, Shulan, Hailar, Hunchun, Liangshui and Qitaihe in Northeast China are collected for combustion test. Burn coal in a nearly-closed burner to prevent material loss caused by fly ash and then measure the ²³⁸U, ²³²Th, ²²⁶Ra and ⁴⁰K activity of coal and corresponding ash. The analysis shows that in the theoretical combustion state, assuming no fly ash is produced, the product of natural radionuclide enrichment factor (f) and ash content ratio(Ad) is 1. According to the migration and enrichment rule of nuclide after combustion and the nuclide weights affecting the radiation level, the paper proposes the reference values of radioactive environment evaluation applied to coal, such as specific activity, absorbed dose rate, annual absorbed dose, and internal radiation index. Verified by 11 coal mines, the results can reflect the radiation level of coal ash with the ranking basically consistent with the actual measurement.