The investigation of natural environmental radiation which constitutes the main source of human exposure is of great importance in health Physics, it is, therefore, necessary to evaluate natural radiation to detect contamination among the population and environment. This research, study the absorbed dose rate and estimated effective dose from naturally occurring radioactive materials (NORMS) 232Th, 238U and 40K within some selected school playgrounds in Birnin-Kebbi, Nigeria. The soil samples were examined with sodium iodide, thallium doped (NaI (TI)) detector connected to a computer-based gamma-ray spectrometer. The calculated average dose rate of the NORMS for the locations was 42.2621 nGy/h with minimum and maximum values of 33.0997 nGy/h and 56.4818 nGy/h respectively. Although locations C (Hajiya Kubura Model Primary School) and E (Aliero Quarters Primary School) have dose rates above the average value, it is however below the “world average value of 60 nGy/h and the maximum allowed health limit of 1500 nGy/h” (UNSCEAR, 2000). Moreover, the average annual effective dose for the locations was found to be 0.6480 μSv/y which is also a little below the world “average of 0.07 μSv/y and an acceptable safety limit of unity (1 μSv/y)” (UNSCEAR, 2000). However, at location E the value was 0.0867 μSv/y which is slightly higher than the world average but lower than the unity value (1.0 μSv/y) the recommended value. In this regard, both the dose rates and annual effective dose of these locations were below the safety limit and worldwide average therefore, children playing in the respective playgrounds are safe from the effects of the radionuclides.
Key words: Absorbed dose rate, effective dose, Gamma-ray spectrometer, naturally occurring radioactive materials (NORMs)
|
