Determination of Absorbed and Effective Dose from Natural Background Radiation around a Nuclear Research Facility

Problem statement: This study presents result of outdoor absorbed dose rate and estimated effective dose from the naturally occurring radionuclides ²³²Th and ²³⁸U series ⁴⁰K, around a Nuclear Research Reactor at the Centre for Energy Research and Training (CERT), Zaria, Nigeria. Approach: A high-resolution in situ γ-ray spectrometry was used to carry out the study. CERT houses a 30Kw Research Reactor and other neutron and gamma sources for Research and Training. Results: The values of absorbed dose rate in air for 232Th, ²³⁸U and ⁴⁰K range from 8.2 ± 2.5-24.5 ± 3.6 nGy h⁻¹, 1.9 ± 1.2-4.6 ± 2.5 nGy h⁻¹ and 12.2 ± 5-38 ± 6.7n Gy h⁻¹ respectively . The estimated total annual effective dose outdoor for the sites range from 27.3-79.9 µSv y⁻¹.Conclusions: This showed that radiation exposure level for the public is lower than the recommended value of 1 mSv y⁻¹.Hence, the extensive usage of radioactive materials within and around CERT does not appear to have any impact on the radiation burden of the environment.