A STUDY OF NATURAL RADIATION LEVELS AND DISTRIBUTION OF DOSE RATES WITHIN THE YOUNGER GRANITE PROVINCE OF NIGERIA

ABSTRACT

A study of natural radiation levels and distribution of dose rates in parts of the Younger Granite Province of Nigeria constitutes this work. It has established the extent and distribution of various parameters of ionizing radiation across the area. By using a combined solid scintillation and gas filled radiation detection techniques, gross gamma as well as gross alpha/beta radiations were detected and measured within the different rock units, the result of which show that radiation levels are high within the younger granites and in parts of the basement areas but low within the basalts. Radiation maps prepared for this area show a good correlation with existing geological maps of the area signifying that natural terrestrial radiation signatures can be used as a tool for regional geological mappings especially in poorly exposed plains. The maps indicate that absorbed dose rates in air range from 0.030-0.431 μGyh-1, while dose equivalents and effective dose rates are well in excess of 1mSv/yr maximum permissible limits in some areas, suggesting a reasonably good chance of radiation hazards in those places. Highest values were found within the Ririwai Sheet 126, attributable to high concentration of radionuclides within both the peralkaline and non-peralkaline granites that constitute the complex. People living in areas identified with high background radiation levels in this study should therefore be made aware of the potential radiation related health problems, while government should also do more to stop the common practice of using mine wastes for foundation fillings and block construction because of the radiological implications.