Evaluation of Annual Effective Dose Equivalent from Environmental Gamma Radiation at Sand Mine Valley in Yenagoa, Nigeria

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Abstract

Annual Effective Dose Equivalent (AEDE) was evaluated from ionizing radiation exposure rates at sand dredging and dump site using Digiler-200 radiation survey meter. Radiation Exposure rates ranged from 0.010mR-h to 0.028mR-h. The result of Annual Effective Dose Equivalent ranged from 0.10 to 0.29 mSvy-1. The average value of absorbed dose was found to be 141.70 nGyh-1. A plot of height of dumped sand with Background ionizing radiation suggests that more radionuclides exist in less washed sand. Computed average values of annual effective dose equivalent (AEDE) and excess lifetime cancer risk (ELCR) were 0.171 mSvy-1 and 0.43 x 10-3 respectively. It was observed that all the radiological indices exceeded the standard value except the annual effective dose equivalent which was based on dose conversion factor of 0.7 and occupancy factor of 0.25, and it is less than the permissible dose limit of 1 mSv/yr set by the International Commission on Radiological Protection. In this regard, the sand is highly recommended as building material since the radiological burden it poses is minimal. However a different batch of dredged sand in the same location may radiate different levels of nuclide therefore regular monitoring is necessary.

Keywords: Evaluation; Effective Dose Gamma Radiation; Sand Dump,,,,

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