External Ionizing Radiation Exposure During Cargo/Vehicle Radiographic Inspection of Nigerian Ports Authority, Onne, Rivers State, Nigeria

Abstract

Cargo inspection technology encompasses the use of ionizing radiation to examine materials, cargo and conveyances at various ports of entry crossing for security related items. Exposure of humans to these ionizing radiation may lead to health hazards therefore evaluation of external ionizing  radiation exposure during the normal scanning operation and when the scanner is not in operation at the Nigeria Ports Authority, Onne seaport, Rivers State was carried out in order to estimate  the health hazards and risks associated with such exposure. An in-situ measurement  of the background radiation of the surrounding environment of the scanning center  was carried out using two well calibrated nuclear radiation meter (Digilert-50 and Radalart-100) and a Global Positioning System (GPS). The area was divided into four (4) zones and radiation exposure rate taken during cargo scanning and also when it is not scanning. The mean radiation exposure rate of four locations during scanning operation ranges from 0.018±0.001mRhr^-1 to 0.060±0.0039mRhr^-1 and the equivalent dose rate ranges from 1.514±0.08mSvy^-1 to 5.004±0.33mSvy^-1. The mean exposure rate of the four locations when the scanning facility was not working ranges from 0.015±0.0024mRhr^-1 to 0.018±0.001mRhr^-1 while the equivalent dose rate ranges from 1.29±0.09mSvy^-1 to 1.49± 0.09mSvy^-1.  The average exposure rate and equivalent radiation dose obtained for each location of the study area including office blocks are above the recommended safe value of 0.013mRhr^-1 and 1.0mSvy^-1 respectively. The results obtained show that the background ionizing radiation of the area has been impacted due to Cargo scanning operation.

Keywords: Radiography, Radiation, Equivalent dose, Exposure, Digilert , Onne and Cargo