Application of nuclear activation analysis (NAA) and low-level gamma counting to determine the radionuclide and trace element-pollutant releases from coal-fired power plants in Vietnam

Results of the application of NAA using research reactors TRIGA II in Dalat, Vietnam, and Vienna, Austria (with pyrolysis separation for Hg, Se and As before irradiation), to determine As, Cd, Cu, Hg, Ni, Co, Pb, Sn and Zn. Low-level gamma counting was used to measure Ra-226, Th-228 and K-40, released from coal-fired power plants in Vietnam. Results showed that: (1) The content of the air pollutants in the vicinity of the operating power plants (in 1991, the Phalai plant produced 1700 million kWh, and the Nimhbinh plant 100 million kWh) depends on the coal combustion which is used for their applied operation technology, both plants used Quangninh anthracite as fuel. The content of trace elements pollutants (TEP) in the environment of the Ninhbinh plant is higher than in the Phalai plant. (2) In the vicinity of both plants, rain water is highly polluted by trace elements such as As, Cu, Pb, Hg, Ni, Co, Cd, Se, U, Th and sulphuric acid. Therefore, this kind of water is not acceptable for human consumption. (3) The algae growing in the waterfield in the vicinity of the power plants can be used to monitor TEP. Four NAA methods, in combination with low-level gamma counting and AAS, can be successfully used to monitor TEP released from power plants.