Natural radioactivity survey on rocks found on Jammu-Kashmir National Highway, Himalayas, India

The two major natural sources through which human society are exposed to radiation externally are terrestrial gamma rays and cosmic rays. Terrestrial gamma rays are derivative of natural radio-nuclides that belongs to ²³⁸U, ²³²Th and ⁴⁰K series and found in the earth's crust. These radio-nuclides (²³⁸U, ²³²Th and ⁴⁰K) are found in soils depending on the distribution of these radio-nuclides in rocks from which they emanate and on the processes at which the soils are concentrated. In this investigation, natural radioactive contents in rocks of Jammu and Kashmir were measured using gamma ray spectroscopy. NaI(Tl) detector was used to estimate the concentrations of some radio-isotopes present in 15 samples of various rocks collected from Jammu - Srinagar National Highway, India. The average activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K for the rocks were found to be 28.30 ± 8.34, 42.02 ± 16.40, and 441 ± 68 Bq/kg respectively. Radiological hazard indices such as absorbed dose rate, radium equivalent activity, external Hazard Index (Hex), internal Hazard Index (Hin), Annual Effective Dose (mSv/y), Gamma activity Index (I?) and Alpha Index (Ia) were also determined. The mean value of radium equivalent obtained in this study is less than that of the International reference value of 370 Bq/kg in rocks given by OECD (1979). Data obtained indicated that rocks of the studied region did not pose any significant radiological health hazards to the local population. (author)