Several studies had been conducted on indoor radon concentrations around thermal power plants. But can anyone provide any data (published) for 222Rn exhalation rates in coal ash produced during thermal power generation?
Nearly 100% of radon in the coal is released during burning.
http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html
Sir, thank you for your reply. Almost 100% release of Rn contained in coal through stack emission is fine. But when disposed, the bottom ash contains a good concentration of 238U and 226Ra, that leads to exhalation of Rn from them. I am interested in that exhalation rate data from different TPPs' (using different coal varieties) bottom ash.
An internet search turns up several reports on exhalation rate from bottom ash and fly ash. The various reports use various methods and definitions.
The usual method is to place ash in a container and measure the equilibrium radon concentration in circulating air. The depth of material in the container varies with report as do preparation methods for the samples. Some dry the samples and/or grind the samples. The drier the sample, the more radon is released. The grind of the samples (my experience) affects the radon release rate. The exhalation rate increases as the particle size decreases until a point is reached where the rate decreases with decreasing particle size. The smaller size particles allow closer packing and reduces the air space. The same increase then decrease is seen as the depth of the ash increases.
It is difficult to compare the exhalation rates when different techniques are used.
The most appropriate exhalation measurement is in situ.
The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) released the new report on 8 February 2017, which is freely downloadable from
http://www.unscear.org/docs/publications/2016/UNSCEAR_2016_Report.pdf
This "UNSCEAR 2016" report discusses dose from various electricity-generating technologies. For radon in coal and resulting exposure, the information is available on its pages please see pages 184-192.
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