Ozden Banu, Guler Erkan, Vaasma Taavi, Horvath Maria, Kiisk Madis, Kovacs Tibor
Ege University, Institute of Nuclear Sciences, Bornova, Turkey.
Dokuz Eylul University, Mining Engineering Department, Buca, Turkey.
J Environ Radioact. 2018 Aug;188:100-107. doi: 10.1016/j.jenvrad.2017.09.016. Epub 2017 Sep 29.
Coal, residues and waste produced by the combustion of the coal contain naturally occurring radionuclides such as U, Ra, Pb, Th and K and trace elements such as Cd, Cr, Pb, Ni and Zn. In this work, coal and its combustion residues collected from Yatagan and Yenikoy coal fired thermal power plants (CPPs) in Turkey were studied to determine the concentrations of natural radionuclides and trace elements, and their enrichments factors to better understand the radionuclide concentration processes within the combustion system. In addition, the utilization of coal fly ash as a secondary raw material in building industry was also studied in terms of radiological aspects. Fly ash samples were taken at different stages along the emission control system of the thermal power plants. Activity concentrations of naturally occurring radionuclides were determined with Canberra Broad Energy Germanium (BEGe) detector BE3830-P and ORTEC Soloist PIPS type semiconductor detector. The particle size distribution and trace elements contents were determined in various ash fractions by the laser scattering particle size distribution analyzer and inductively coupled plasma (ICP-OES). From the obtained data, natural radionuclides tend to condense on fly ash with and the activity concentrations increase as the temperature drop in CPPs. Measured Pb and Po concentration varied between 186 ± 20-1153 ± 44 Bq kg, and 56 ± 5-1174 ± 45 Bq kg, respectively. The highest Pb and Po activity concentrations were determined in fly ash taken from the temporary storage point as 1153 ± 44 Bq kg and 1174 ± 45 Bq kg, respectively. There were significant differences in the activity concentrations of some natural radionuclide and trace elements (Pb and Zn) contents in ash fractions among the sampling point inside both of the plants (ANOVA, p < 0.001). Coal and ash sample analysis showed an increase activity concentration and enrichment factors towards the electrostatic precipitators for both of the power plants. The enrichment factors for Zn follow a similar trend as Pb, increasing in value towards the end of the emission control system. The calculated activity indexes were above 1.0 value for both of the power plants, assuming the utilization of fly ash at 100%. It can be concluded that the reuse of fly ash as a secondary raw material may not be hazardous depending on the percentage of utilization of ash.
煤炭、煤炭燃烧产生的残渣及废弃物含有天然存在的放射性核素，如铀、镭、铅、钍和钾，以及镉、铬、铅、镍和锌等微量元素。在本研究中，对从土耳其亚塔甘和耶尼科伊燃煤热电厂收集的煤炭及其燃烧残渣进行了研究，以确定天然放射性核素和微量元素的浓度及其富集因子，从而更好地了解燃烧系统内的放射性核素浓缩过程。此外，还从放射学角度研究了粉煤灰作为建筑工业二次原料的利用情况。在热电厂排放控制系统的不同阶段采集了粉煤灰样品。使用堪培拉宽能锗（BEGe）探测器BE3830 - P和ORTEC Soloist PIPS型半导体探测器测定天然存在的放射性核素的活度浓度。通过激光散射粒度分布分析仪和电感耦合等离子体（ICP - OES）测定不同灰分中的粒度分布和微量元素含量。根据所得数据，天然放射性核素倾向于在粉煤灰上凝结，并且在热电厂中随着温度下降活度浓度增加。测得的铅和钋浓度分别在186±20 - 1153±44 Bq/kg和56±5 - 1174±45 Bq/kg之间变化。在取自临时储存点的粉煤灰中测得的铅和钋的最高活度浓度分别为1153±44 Bq/kg和1174±45 Bq/kg。两座电厂内部采样点的灰分中，某些天然放射性核素和微量元素（铅和锌）含量的活度浓度存在显著差异（方差分析，p < 0.001）。煤炭和灰分样品分析表明，两座电厂的静电除尘器处的活度浓度和富集因子均有所增加。锌的富集因子与铅的趋势相似，在排放控制系统末端其值增加。假设粉煤灰的利用率为100%，两座电厂计算出的活度指数均高于1.0。可以得出结论，根据灰分的利用率，粉煤灰作为二次原料再利用可能并无危害。
