Measurements of radionuclides in coal samples from two provinces of Pakistan and computation of External γ ray dose rate in coal mines

The radionuclides present in coal may not only be a health hazard for the coal miners but also may be a threat to the general population if these radionuclides disperse in the environment. This research has been conducted to quantify the radionuclides present in the coal samples from various coal-mines of two provinces, Punjab and Balochistan of Pakistan. In this regard, a high-purity Ge-detector-based γ-spectrometer was used. The maximum activity concentrations for 226Ra, 232Th and 40K were found to be 31•4±3•0, 32•7±3•2 and 21•4±5•0 Bq kg-1, respectively. A theoretical model to compute external γ-ray dose rate from a coal-mine surface was developed. The Monte Carlo simulation was employed to compute the required mass attenuation coefficients corresponding to the various γ-ray energies from 226Ra, 232Th, their progeny and 40K present in the coal samples. In addition, the effective thickness of coal slab for self-absorption was also computed using the Monte Carlo Neutron Photon (MCNP) transport code. The computed external γ-ray dose rate has been found to be much below the dose ratelimits for occupational persons as well as for the general population.