Hazards from radioactivity of fly ash of Greek coal power plants (CPP)

Fly ash and fine dispersion releases by coal combustion in Greek coal power plants are radioactive. Concentrations in the fly ash up to 20 pCi/g and 10 pCi/g were measured for 238U and 226Ra respectively (not in secular equilibrium). The radioactivity of fly ash deduces risks in two ways: a) from the escaping fly ash in particulate form or fine dispersion and b) from using fly ash as substitute for cement in concrete. In a room of dimensions 10 x 10x4 m3 the concentration of Radon in the air will be about 10-9 μCi/cm3. For the above estimation a concrete porosity of 5% and a wall thickness of 20 cm was used. The estimated concentration of Radon was about two orders of magnitude lower than that of the MPC of Radon in the air, which is about 10-9 μCi/cm3. It is pointed out that if a 25% porosity were used, the Radon concentration will be an order of magnitude higher. (U.K.)