Artificial and Natural Radioactivity Measurements and Radiation Dose Assessment in the Vicinity of Ghana Nuclear Research Reactor-1 (GHARR-1)

Abstract

Radioactivity concentrations of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs in soil samples and water sources around the Ghana Research Reactor-1 (GHARR-1) and the immediate surroundings have been measured using gamma spectrometry. The primary aim of the study was to establish baseline radioactivity levels in the environs of GHARR-1. The average activity concentration of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were 22.3 ± 1.12 Bq kg^-1, 49.8 ± 1.60
Bq kg-1, 99.60 ± 5.81 Bq kg^-1 and 1.48 ± 0.25 Bq kg^-1 for soil and 0.60 ± 0.11 Bq l^-1, 2.13 ± 0.21 Bq l^-1, 10.75 ± 0.84 Bq l^-1 and 0.47 ± 0.05 Bq l^-1for the water, respectively. The ²²⁶Ra and ²³²Th concentrations compare quite well with world averages, whilst the ⁴⁰K concentration was lower than the world average. The levels of ¹³⁷Cs observed in the samples are within the range of ‘background’  concentrations. The estimated average annual effective doses from external exposure to soil and ingestion of water samples were calculated to be 0.06 mSv and 0.53 mSv, respectively. The estimated outdoor  external gamma dose rate measured in air ranged from 20-430 nGy h^-1 with an average value of 100 nGy h^-1, which is higher than the world average value of 59 nGy h^-1. In the case of water samples, the average value was higher than the guidance level of 0.1 mSv y^-1, as recommended by the European Union and the World Health Organization.