This paper presents an assessment of background radiation levels within the Niger Delta University campus, Bayelsa State Nigeria. A portable Geiger-Muller tube (Radiation Alert) was used to detect the background ionizing radiation within a temperature range of -100 â„ƒ to 500 â„ƒ. Results of absorbed dose rate in air in the main campus, open field and new campus varies from 104.4 nGy/h to 278.4 nGy/h with an average of 156.6 nGy/h, 34.8 nGy/h to 174.0 nGy/h with an average of 95.7 nGy/h and 69.6 nGy/h to 174.0 nGy/h with an average of 113.1 nGy/h respectively. The annual effective dose estimates ranged from 0.160 mSv/y to 0.427 mSv/y with an average of 0.024 mSv/y, 0.053 to 0.267 mSv/y with an average of 0.147 mSv/y and 0.107 to 0.267 mSv/y with mean 0.173 mSv/y in the main campus, open field and new campus respectively. The excess lifetime cancer risks ranged from 0.442 to 01.174 x 10-3 with a mean of 0.663 x 10-3, 0.146 to 0.736 x 10-3 with an average of 0.405 x 10-3 and 0.295 to 0.736 x 10-3 with average 0.479 x 10-3 in main campus, open field and new campus respectively. The estimated averages of absorbed dose rates in the air within Niger Delta University were above the world average of 57 nGy/h. Annual Effective Dose Equivalent (AEDE) are below the safe limit of 1 mSv/y for humans. The results of this study provide baseline information on the background ionizing radiation and can be referenced for future works in the area.
The measurement of possible presence of radiofrequency (RF) radiations from telecommunication base stations was carried out within Kaduna North Area of Kaduna State, to estimate the maximum level of power density from RF radiations to which the member of the populace within specific radius from the base transceiver station (BTS) are exposed to in relation to the existing guidelines to human exposure. Power density S (ÂµWm-2) measurements were made at interval of 20 m to check the exposure level at public locations from 10 RF antenna sites starting from the foot of each BS to distance (radius) of 100 m using Aaronia Spectran HF-4060 Analyser and the electric field strength E (Vm-1) were calculated. The highest and lowest value obtained from measured mean power densities were 108.27 ÂµWm-2 and 94.74 ÂµWm-2 from a distance of 100 m and 40 m respectively. Also, the highest and lowest average electric field strength were 202.03 (Vm-1) and 188.99 (Vm-1) at 100 m and 40 m respectively. The result obtained, indicates that the measured values were far less than the permissible exposure limits for both workers and the general public as set by the International Commission on Non-ionizing Radiation Protection (ICNIRP). These results shows that the exposure levels in these areas are low and as such will not pose significant health risks to the people living in the study area.
Tropospheric radio wave signals experience loss due to multipath effect, scattering and other forms of attenuation through the atmospheric medium, primarily due to variations in weather conditions with time. The knowledge of surface refractivity profile is important for optimal planning of Very High Frequency/Ultra High Frequency (VHF/UHF) terrestrial radio links in a region. The study of surface refractivity (Ns) over the North-Central Nigeria was carried out using meteorological data from seven locations in North-Central zone of Nigeria. The seasonal variations of Ns were also derived using the monthly summaries of surface data obtained from Nigerian Meteorological Agency (NIMET) over seven stations of Abuja, Lafia, Lokoja, Makurdi, Jos, Minna and Ilorin between 2005 and 2010.The results indicated that the monthly averages of radio refractivity during the rainy season months (April to October) are greater than the Ns values during the dry season months (November to March) for all the locations throughout the years of the study. The computed of mean monthly Ns over all the seven stations in the first 1 km above the ground level is 348 N-units, which gives mean refractivity gradient (dN/dh) of -49 N/k, these shows that the region is characterised by low scale super-refraction. The mean k-factor over the entire region in the first 1 km above the ground level is 1.4; the mean Field Strength Variability (FSV) in first 1 km of height in the region was calculated to be 14 dB. The mean Radio Horizon distance within 1 km height for a transmitter height of 100 m over the stations is 42 km. The results provide useful information needed by radio engineers to set up new terrestrial radio propagation links or to improve on the existing ones especially at VHF, UHF in the North-Central region of Nigeria, as recommended by International Telecommunication Union Recommendations (ITU-R P.453, 2013), which observed the need for local reference data on refractivity and refractivity gradients all over the world.
Qualitative analysis of radionuclides requires the use of reliable gamma-ray detection system. The NaI (Tl) detector has been widely used and still one of the most used detectors today. It is therefore imperative to validate the reliability of the 5Ã—5 cm^2 NaI (Tl) gamma spectrometry system used in carrying out gamma-ray analysis of soil samples in the Radiation and Health Laboratory, Federal University of Agriculture Abeokuta, Nigeria. The gamma ray spectrometer is housed in a 5 cm thick cylindrical lead shield. Calibration was executed using standard materials produced under the auspices of the International Atomic Energy Agency (IAEA). Resolution and detection limit (LD) of the detector were determined using full width at half the maximum of the energy peak of 137Cs and background signal level of the reference materials respectively. Counting efficiencies of the detector was calculated using energies of 1460keV, 1764 keV and 2615 keV for 40K, 226Ra and 232Th respectively. Secondary samples, RGMIX1 and RGMIX2 were formulated and counted to calculate activity concentrations using the NaI (Tl) detector. Resolution of the detector was calculated to be 7.8% of 137Cs, which is good for a NaI (Tl) detector. The counting efficiency of the detector is seen to depend on the gamma ray energy. The results from this work shows that the detector system is suitable for gamma spectrometry, and will give quality measurements when used for quantitative determination of radionuclides in environmental samples. The efficiency and resolution of the NaI (Tl) detector could also be determined using photon energies obtained from other radioactive sources.
n this paper the washability of a stitched transmission line is been studied. The aim is to determine the deterioration of the frequency dependence of the scattering parameters of the stitched transmission line after subjecting it to washing cycles using a domestic washing machine. The DC resistance of the stitched transmission line was measured before and after wash with results indicating an increase in the DC resistance from 16.9 â„¦ to 22.8 â„¦ after washing the stitched transmission line. The increase in DC resistance is due to the decrease in conductive path of the stitched transmission line as a result of the abrasion impacts in the washing machine leading to increased number of fissures and defects on the stitched transmission line. The propagation characteristics of the stitched transmission line were investigated using CST Microwave Studio SuiteÂ® and measurements on the stitched transmission line before and after wash was carried out using an Anritsu MS46524A 7GHz Network Analyser for a frequency range of 0.04 to 4 GHz, with results demonstrating that the stitched transmission line will make a good candidate for wearable applications.