Distribution of natural occurring radionuclide in some industral residues used in new type wall materials

Objective: To study the natural radioactive nuclide distribution characteristic of fly ash, gangue and various kinds of slag used in the new-type wall material and offer scientific basis for reducing the radiation dosage that the public suffers. Methods: The activity concentrations of the contents of natural radioactive nuclides of different industral waste residues have been determined by HPGe gamma-ray spectrometry. Results: The mean Raeq is successively fly ash (279.13 Bq kg-1), slag (225.69 Bq kg-1), gangue (141.26 Bq kg-1) from high to low and all of the samples is lower than the limit set in the OECD. The arithmetic mean activities of 236Ra, 232Th, 40K in fly-ash samples are 127.88, 93.83, 221.75 Bq kg-1; for coal slag samples are 73.89, 97.13, 283.44 Bq kg-1 and for coal gangue samples are 47.85, 45.21, 413.56 Bq kg-1. For the same power plant, the radioactive nuclide activity of the fly ash gathered in different time may have very great differences, the maximum can reach more than 2 times of the minimum. Conclusion: the fly ash and slag should be controlled strictly on rational proportion, which should not exceed 70% of the total mass. The mixing of the average radioactive level of the gangue is nearly equal that of to clay, it can be unrestricted in the mixing proportion in process of production. The manufacturer of new-type wall materials should often measure the radioactive level of the industrial waste residue in production. Make the content of radioactive nuclide in the products reach the rational level as low as possible. (authors)