Radiological safety assessment was carried out to assess the integrity and longevity of the barrier systems of the borehole disposal system (BDS) for the disposal of disused sources in Ghana. The design of the BDS incorporates both the engineered and natural barriers into its safety concept. The safety of the BDS requires confidence in the ability of the engineered barriers on the host environmental conditions to provide containment for the disused sources for a sufficient length of time. The results obtained from the scoping tool indicated that the dose limit was exceeded which showed that the containment provided by the engineered barriers was not sufficient to ensure safety of the disposal system for the specified environmental conditions and radionuclides inventory. Detailed modelling was performed with an AMBER model to evaluate the containment provided by the engineered barriers and the geosphere with some identified scenarios. The AMBER model results showed that the calculated peak dose from any of the disposed radionuclides for the identified scenarios was below the dose constraint of 0.3 mSv/y. The peak doses occurred around 2000-1000000 years. The peak doses were seen to be mainly derived from Ra-266 and Am-241 and/or their daughters. The disused sources could be disposed of safely in the disposal system either in an oxidizing or reducing fractured/porous flow environment without posing any significant radiological threat to humans and the environment.

Activity concentrations of the Naturally Occurring Radioactive Materials (NORMs) in some bottled drinking water brands obtained from some supermarkets in Accra were analyzed using gamma spectrometry.40 K activity concentrations were in the range of 3.57 - 5.47 Bq/L, the highest occurring in brand L9. Similarly,232 Th activity concentrations were in the range of 0.30 - 0.56 Bq/L with the highest occurring in brand L8. 226 Ra was identified in eleven brands with the remaining 5 below detection limit. The highest value (0.53 Bq/L) occurred in brand L9. Comparison of the mean concentrations showed significant differences at (α = 0.05) between the various brands of bottled water. Estimated committed effective doses were generally below 0.1 mSv/a for all age groups with the exception of children <1yr. Estimated lifetime cancer and hereditary risk were done using the ICRP risk assessment methodology.

13Oct 2018 RADIOLOGICAL HAZARD ASSESSMENT FOR FLY ASH AND ENVIRONMENTAL MATERIALS FROM MORUPULE A COAL-FIRED POWER STATION IN BOTSWANA. John Mudiwa , E. O. Darko and A.Faanu. School of Nuclear and Allied Sciences, University of Ghana, Legon-Accra, Ghana. Radiation Protection Institute, Ghana Atomic Energy Commission, Accra, Ghana.

The present paper has determined the radioactivity concentrations, which are due to natural occurrence of radionuclides along with heavy metal concentration in water, sediment, and fish from 2 reservoirs in Ghana. Heavy metal concentrations in all samples were generally within the WHO safe limits with the average activity concentrations of 238U, 232Th, and 40K in water being respectively 0.42 +/- 0.20, 0.33 +/- 0.31, and 1.59 +/- 1.07 Bq/L in case of Lake Bosomtwe and 0.26 +/- 0.14, 0.67 +/- 0.34 and 1.47 +/- 0.62 Bq/L for Bui Dam in Ghana. The average annual effective dose due to ingestion of radionuclides in water ranged from 20.5 to 156 for Lake Bosomtwe and 26.5 to 162 mu Sv/year for Bui dam and the absorbed dose rate and annual effective dose, measured for Lake Bosomtwe, was 15.45 +/- 2.00 nGy/year and 18.95 +/- 2.95. S/year respectively while in case of Bui dam it accounted to 10.44 +/- 4.11 nGy/year and 12.88 +/- 5.01. S/year respectively, found to be within the UNSCEAR recommended limits of 59 nGy/year and 100. S/year respectively. The observed metal concentrations, within safety limits, imply that metal-associated diseases cannot be expected among patrons of these reservoirs. Therefore, radionuclides and heavy metals levels in the reservoirs are not expected to cause any significant health problem for humans.

Hazards attributable to the natural radionuclides present in beach sands, from ten (10) landing beaches in the Volta Region of Ghana, was assessed in this study.The terrestrial radiation exposure levels on the beaches, in addition to hazards humans may face when exposed to the analyzed sands were determined.Gamma-spectrometry was used to assess specific activities of radionuclides in the samples.Three different radiological hazard indices analogous to radiation hazards were estimated.Total absorbed gamma dose rate in the air and equivalent annual effective dose were assessed.The resulting specific activities range from 1.87 -17.53 Bq Kg -1 for 226 Ra, 3.84 -24.81 Bq Kg -1 for 232 Th and 77.40 -1103.90 for 40 K, while mean values of 30.02 nGy h -1 , 0.18 mSv y -1 , 61.24Bq kg -1 , 0.17 and 0.19 were obtained, for absorbed dose rate, annual external effective dose, radium equivalent activity, external hazard index and internal hazard index respectively.The sands from the beaches studied cannot be considered as a radiological hazard to human safety and health.

Levels of naturally occurring radioactive materials prior to processing of gold ore within and around the new eastern concession area of Perseus Mining (Ghana) Limited were carried out to ascertain the baseline radioactivity levels. The study was based on situ measurements of external gamma dose rate at 1 m above ground level as well as laboratory analysis by direct gamma spectrometry to quantify the radionuclides of interest namely; 238U, 232Th and 40K in soil, rock, ore samples and gross alpha/beta analysis in water samples. The average absorbed dose rate in air at 1 m above sampling point using a radiation survey metre was determined to be 0.08 ± 0.02 μGyh−1 with a corresponding average annual effective dose calculated to be 0.093 ± 0.028 mSv. The average activity concentrations of 238U, 232Th, and 40K in the soil, rock, and ore samples were 65.1 ± 2.2, 71.8 ± 2.2 and 1168.3 Bqkg−1 respectively resulting in an average annual effective dose of 0.91 ± 0.32 mSv. The average Radium equivalent activity value was 257.8 ± 62.4 Bqkg−1 in the range of 136.6–340.2 Bqkg−1. The average values of external and internal indices were 0.7 ± 0.2 and 0.9 ± 0.2 respectively. The average gross alpha and gross beta activity concentrations in the water samples were determined to be 0.0032 ± 0.0024 and 0.0338 ± 0.0083 Bql−1 respectively. The total annual effective dose from the pathways considered for this study (gamma ray from the soil, rock and ore samples as well as doses determined from the gross alpha/beta activity concentration in water samples) was calculated to be 0.918 mSv. The results obtained in this study shows that the radiation levels are within the natural background radiation levels found in literature and compare well with similar studies for other countries and the total annual effective dose is below the ICRP recommended level of 1 mSv for public exposure control.

1. He thought the minimum detectable activity (MDA) value for K is too low, the counting time was too short based on his experience and why distilled water was used. First of all the distilled water was used to limit the level of backscatter radiation within the detector system during the background count. Also, we want to state that a low background spectrometry system was used for the counting. In other to optimize the result of the background count and the real samples, the same counting time was used. We agree that the longer the counting time the greater the peak area, however, based on the prevailing laboratory condition which could not enable us to consider a longer counting time 36,000 was used which could also give an appreciable count rate. The MDA is defined as the smallest quantity of radioactivity that could be measured under specified conditions, and is another factor which is an important concept in environmental level measurement. The MDA depends on the lower limit of detection (LLD) and the counting efficiency of a counting system. The MDA is very important, particularly in environmental level systems, where the count rate of a sample is almost the same as the count rate of the background. The MDA was calculated using the conventional MDA method based on statistical convergence of 95 % confidence level. The value obtained for K was based on experimental data and calculation done using the conventional method.

Produced water from two Ghanaian offshore production oilfields has been characterized using alpha spectrometry after radiochemical separation, non-destructive gamma spectrometry and ICP-MS and other complimentary analytical tools. The measured concentrations of main NORM components were in the range of 6.2-22.3 Bq.L-1, 6.4-35.5 Bq.L-1, and 0.7-7.0 Bq.L-4 (f)or Ra-226, Ra-228 and Ra-224 respectively. A good correlation between several physico-chemical parameters and radium isotopes was observed in each production oilfield. The radium concentrations obtained in this study for produced water from the two oilfields of Ghana are of radiological importance and hence there may be the need to put in place measures for future contamination concerns due to their bioavailability in the media and bioaccumulation characteristics. The results will assist in critical decision making for future set up of appropriate national guidelines for the management of NORM waste from the emerging oil and gas industry in Ghana. (C) 2015 Elsevier Ltd. All rights reserved.

Direct gamma spectrometry study was carried out within lower basin of river Pra to ascertain the baseline radioactivity levels of naturally occurring radioactive materials. The average activity concentrations of 238U, 232Th and 40K in the soil and sediment were 25.51, 28.04 and 238.98 Bqkg−1 for soil, and 16.02, 20.31 and 27.39 Bqkg−1 for the sediment. The study indicated that the activity concentrations of 238U, 232Th and 40K in the water were calculated to be 2.51, 1.71 and 41.43 BqL−1, respectively and the corresponding annual effective dose ranged from 0.35 to 3.91 with an average of 1.82 μSvyear−1. These values are within the levels allowed elsewhere or recommended by the WHO.

Globally, the cement industry has been identified as one which causes significant particle pollution. In Ghana, environmental research in the neighborhood of the cement industry especially on human health is scanty. In the present work, attempts were made to evaluate the concentration of airborne dust at various distances and directions around the Diamond Cement Factory in the Volta Region of Ghana. The samples of dust were collected on filter papers and later analyzed for the concentration (mg/kg) of 232 Th and 238 U using neutron activation analysis. The principal objective of the study was to generate data intended at assessing the annual effective dose due to 232 Th and 238 U inhalation for both adult and children population living in the vicinity of cement factory. The data generated were supposed to assist in remediation decision making, if required. The study recored a few incidences of higher total dust load concentrations as compared to the permissible limit of 150 μg/m 3 specified by the Ghana Environmental Protection Agency. The calculated mean effective doses were 28.2 ± 1.06 μSv/year and 25.9 ± 0.91 μSv/year for both adult and child, respectively. From the radiological point of view, the study concluded that the people living in the vicinity of the cement factory are not at risk to significant radiological hazards. However, the study indicated the need to have a complete evaluation of the impact of the factory on the environment assessment programs which should include both chemical and radiological toxicity.

Studies have been carried out within and around the operational area of the Chirano Gold Mine Ltd of Ghana to ascertain the baseline radioactivity levels of naturally occurring radioactive materials as well as artificial radionuclides in the surface and underground mines. The analysis was carried out by using gamma spectrometry to quantify the radionuclides of interest, namely (238)U, (232)Th, (137)Cs and (40)K in soil, ore, waste rock and water samples. The average activity concentrations of (238)U, (232)Th, (40)K and (137)Cs in the soil/rock samples were 9.79±5.39, 9.18±7.06, 237.40±144.34 and 0.64±0.57 Bq kg(-1), respectively. For the water samples, the average activity concentrations were 0.86±0.67, 0.97±1.33 and 9.05±10.45 Bq l(-1) for (226)Ra, (232)Th and (40)K, respectively. The total annual effective dose to the public was estimated to be 0.13 mSv, which is below the International Commission on Radiological Protection recommended level of 1 mSv for public exposure control. The study also assessed the elemental concentrations of U, Th and K in the soil/rock samples from the gold mine and surrounding communities. The average concentrations of the U, Th and K were 0.82±0.48, 2.18±1.77 µg g(-1) and 0.77±0.47 %, respectively. The concentrations of U, Th and K were variable in soil and rock samples taken from different locations in the study area with values varying in the range 0.28-2.21, 0.24-6.50 µg g(-1) and 0.28-1.87 %, respectively. The concentrations of U, Th and K are far lower than the world average values but comparable with the range of similar studies for different countries. The concentration values of gross-alpha and gross-beta for all the water samples were below the Ghana Standards Authority and World Health Organisation recommended guideline values for drinking water quality. The results obtained in this study also show that radiation levels are within the natural background radiation levels found in the literature and compare well with those of similar studies for other countries including Ghana.

Radiometric determinations have been carried out to assess public exposure to radioactivity for communities along the coast of a shallow water offshore oilfield in Ghana (which started their operations recently) in order to establish baseline data using alpha spectrometry after radiochemical separation and non-destructive gamma spectrometry. The average activity concentrations of (234)U, (238)U, (230)Th and (232)Th by alpha-particle spectrometry and of (226)Ra, (228)Ra, (228)Th, (40)K, (210)Pb, (234)Th and (137)Cs by gamma-ray spectrometry were determined in the soil samples. The activity concentrations of (234)U, (238)U, (230)Th and (232)Th were determined in the water samples by alpha-particle spectrometry and of (226)Ra by liquid scintillation counting. The total annual effective dose to the public was estimated from the measured activity concentrations and this was clearly below the International Commission on Radiological Protection (ICRP) reference level of 1 mSv y(-1) for public exposure control. In addition, the estimated values of Raeq, Hex and Hin were all lower than the recommended acceptable values and the mean values of gross alpha and gross beta determinations performed for all the water samples give values that were all below the Ghana Standards Authority and World Health Organization recommended guideline values for drinking water quality. The results obtained show insignificant public exposure to radioactivity. However, this study provides important information for future studies on subsequent evaluations of the possible future environmental contamination due to activities of the oil industry in Ghana.

Direct gamma spectrometry study was carried out within and around the operational area of the Central Ashanti Gold of Ghana to ascertain the baseline radioactivity levels of naturally occurring radioactive materials (NORM), prior to processing of gold ore at the mine. The average activity concentrations of 238U, 232Th, 40K and 137Cs in the soil/rock samples were 64.3, 68.4, 1243.9 and 3.5 Bqkg−1, respectively. For the water samples, the average activity concentrations were 2.5, 2.6, 14.7 and 0.7 BqL−1 for 238U, 232Th, 40K and 137Cs, respectively. The total annual effective dose to the public was estimated to be 0.141 mSv which is below the ICRP recommended level of 1 mSv for public exposure control. The average radium equivalent activity value was 257.8 Bqkg−1 in the range of 72.9–402.3 Bqkg−1. The average values of external and internal indices were 0.7 and 0.8, respectively. The concentrations of U, Th and K were variable in soil and rock samples taken from different locations in the study area with values varying in the range of 0.8–10.9, 2.4–39.4 μg/g and 0.7–6.3 %, respectively. The concentration values of gross-α and gross-β for all the water samples were below the Ghana Standards Board and Who Health Organisation recommended guideline values for drinking water quality. The results obtained in this study shows that radiation levels are within the natural background radiation levels found in literature and compared well with similar studies for other countries.

In this study, the radioactivity levels of 226 Ra, 232 Th and 40 K and the artificial radionuclide 137 Cs in fresh and processed spices were determined using gamma spectrometry.The assessment of the ingested dose in these radionuclides via food consumption was also made.The natural spices considered in the study were Onion, Garlic, Ginger, Ashanti Pepper, and Green Pepper and the processed spices were Adja, Benny, Maggi, Mamita, Jumbo, Napa Valley, Onga, Royco, Mimido, and Gino Curry Powder.The study focused on these spices because they are commonly available and