Average Annual Effective Dose Rate Research Articles

Determination of Natural Radioactivity Levels and Resultants Radiological Hazard from Soil Samples around Gold Mining Area in Ijesa-land South-Western Nigeria

Activity concentration levels and some radiological parameters owing to natural radioactivity in the soil samples randomly obtained in gold tailing sites in Ijesa­-land Southwestern Nigeria were analyzed. Analyzed results from 30 soil samples using multi-channeled NaI gamma detector show that the activity concentration of 233U; ranged from 17.42 0.54 to 49.892.42 BqKg-1; 232Th ranged from 22.10 4.70 to 76.557.44BqKg-1 and 40K; ranged from 307.0023.90 to 693.5851.50 BqKg-1 in the samples were measured. The mean absorbed dose rate calculated was marginally higher than the world average of 59nGyh-1. The average annual effective dose rate (outdoor) for all samples ranged from 0.08 + 01. 11mSv.y-1 with a mean of 0.07 which stays far below the permitted worldwide limit of 1mSv.y-1hy by International Commission on Radiation Protection (ICRP 2010). The calculated hazard indices for external and internal remained to be lower than unity signifying that mineworkers and individuals active in such area are not exposed radiation hazard.

Study on the Radioactivity Levels of Metal Tailings in the Lhasa Area of Tibet

The main purpose of this study was to determine the natural radioactivity level of raw radionuclides in the metal tailings of a mine in Lhasa, Tibet, and to conduct sampling and detection in 17 typical metal tailing mines in Lhasa, Tibet. The specific activity concentrations of 226Ra, 232Th, and 40K in the samples were calculated. The total αβχγ radiation, radon concentration, and outdoor absorbed dose rate in the air 1.0 m above the ground were measured. The γ radiation levels affecting miners and their surrounding residents were assessed. The results show that the radiation dose ranges from 0.08 μSv/h to 0.26 μSv/h, and the radon concentration ranges from 10.8 Bq/m3 to 29.6 Bq/m3, which does not exceed the national radiation-related standards, and the environmental hazard risk is low. The specific activity concentration of 226Ra ranged from 8.91 Bq/kg to 94.61 Bq/kg, the specific activity concentration of 232Th ranged from 2.90 Bq/kg to 89.62 Bq/kg, and the specific activity concentration of 40K was less than MDA to 762.89 Bq/kg. The average absorbed dose rate (DO) of the 17 mining areas was 39.82 nGy/h, the average annual effective dose rate (EO) was 0.057 mSv/y. The average external risk index of the 17 mining areas was 0.24, the average internal risk index was 0.34, and the average γ index was 0.31, all of which were less than the maximum permissible limit. This means that the metal tailings from all 17 mining areas were within the limit for γ radiation and, therefore, can be used in bulk as major building materials without posing a significant radiation threat to the residents of the study area.

ASSESSMENT OF NATURAL IONIZING RADIATION IN TWO TERTIARY INSTITUTIONS OF NIGER STATE

Background ionizing radiation attributed to natural sources has over the years been at increase due to increase in infrastructural facilities and population inducing more human activities within campuses. This called for very great concern because of it effects on the human at higher exposure doses. Consequently, the Assessment of the Natural Ionizing Radiation was carried out at Ibrahim Badamasi Babangida University, Lapai (IBBUL) and Niger State Polytechnic, Zungeru (NSPZ) with approximate populations of 7000 and 5200 students respectively. A portable Geiger-Mueller dosimeter was used at 19 different locations within the two tertiary institutions. The results revealed the Dose Rate variation from 0.14 to 0.186 μSv⁄hr, at IBBUL, while at NSPZ the variation was from 0.12 to 0.158 μSv⁄hr. For all the locations the mean Dose Rate was 0.154 μSv⁄hr with a standard deviation of 0.0195 μSv⁄hr. Generally, average Annual Effective Dose Rate obtained is 0.27 mSv/annum which fell within the recommended alarming limit of 1 mSv/annum given by the International Commission on Radiation Protection (ICRP) for non-occupational population exposure. This implied no adverse impact on the tenements within the two tertiary Institutions. However, part of the recommendations is that more work needs to be done on the soil to characterize the areas for possible radioactive source deposits which may be up to alarming magnitude in the near future.

Assessment on Radiation Hazard Indices from Selected Dumpsites in Lafia Metropolis, Nasarawa State, Nigeria

This research reports an assessment of ionizing radiation in some chosen Dumpsites in Lafia Local government area of Nasarawa State. Ionizing radiation measurement was conducted at four Dump sites. The survey was done using a radiation survey meter (Radex one Outdoor 55130719 NA). Radiation exposure rate in micro sievert per hour (μSvhr-1) was measured. Readings were taken by placing the detector at gonad level about 1 meter above the ground. Result showed that the average annual effective dose rate in the selected dumpsites were 0.22 mSv/yr for Lafia modern market, 0.17 mSv/yr for dumpsite opposite governor Isa house, 0.15 mSv/yr for Timber shade Lafia and 0.20 mSv/yrfor Science School Lafia respectively with a mean value of 0.19 mSv/yr for all location, while the mean calculated excess life cancer risk (ELCR) is 0.65 x 10-3.Dumpsites yearly absorbed dose rate and their corresponding ELCR values did not exceed the 1.0 mSv/y Basic Safety Standard set for the masses by International Council on Radiation Protection (ICRP, 1999) and mean world average ECLR value of 1.16 x 10-3. Based on these results there are no radiation consequence to the scavengers, dumpsite workers and residents living around the dumpsites.

Annual effective dose from radon-222 concentration levels in underground water in bungoma south sub - county, Kenya

This research measured the concentration levels of radon in groundwater and determined the ingestion and inhalation dose. The study used RAD7 detector with RAD7-H2O accessory from Durridge Company to determine the radon levels. Thirty water samples in granitic dominated regions were collected from various areas of Bungoma County: ten from boreholes (BH), ten from hand dug wells (WL) and ten from springs (SP). The water samples were collected in 250 ml bottles which were tightly covered with lid to avoid radon leakage. The highest value was 303±4.00 KBq/m3 recorded in Kanduyi well and the lowest was 126±11.4kBq/m3 from where most of the samples recorded a high radon concentration with a mean of 269±5.25 KBq/m3 in wells, 213±7.96 KBq/m3 in boreholes and 290±7.70 KBq/m3 in springs. The average ingestion dose was found to be 1.5±0.07mSv/yr, 1.9±0.09 mSv/yr and 2.1±0.1 mSv/yr. The average annual effective dose rate for the samples collected were 2±0.1 mSv/yr for boreholes, 2.6±0.13 mSv/yr for wells and 2.7±0.14 mSv/yr for springs. The samples reported an average value of AED higher than the world average of 1.15 mSv/yr but below the exception limit of recommended action level of 10 mSv/yr hence the radon concentration levels in underground water in the study area has minimal health implications to the population.

EVALUATION OF INDOOR/OUTDOOR GAMMA EXPOSURE RATES AND EXCESS LIFE TIME CANCER RISK IN DIFFERENT CITIES OF PAKISTAN.

This study presents a detailed measurement of indoor and outdoor terrestrial gamma radiation levels in different cities of Pakistan. The measurements covered dwellings in 27 cities, covering all provinces and region of Azad Kashmir. Most of the houses were of attached type, made of brick walls and concrete roofs. The measurements were made by a handheld radiation survey meter containing Geiger-Muller tube. The average absorbed dose rate in air was 100±32 nGy h-1 for indoor and 74±30 nGy h-1 for outdoor. The population-weighted mean terrestrial dose rates were 90 nGy h-1 for indoor and 78 nGyh-1 for outdoor. The ratio of indoor to outdoor absorbed dose rate was 1.5 as compared to 1.3 for the world average. The estimated average annual effective dose rate was 0.58±0.18mSv a-1 and the mean excess life time cancer risk was 2.0×10-3.

Annual Effective Dose from Natural Background Radiation in Pokhara, Nepal

Measurement of outdoor natural background radiation doses at different locations of Pokhara city, Nepal was carried out using GCA-07W, Nuclear Regulatory Commission (NRC) certified Geiger Muller (GM) detector. From the measurements, the least value of background radiation dose rate was found to be 0.26 ± 0.08 μSv/hr for Mahendra Cave area, and the highest value of dose rate was found to be 0.65 ± 0.12 μSv/hr for Prithvi Narayan Campus. The average annual effective dose rate of Pokhara city was found to be 0.56 ± 0.12 mSv/yr ranging from 0.31 ± 0.09 mSv/yr to 0.80 ± 0.14 mSv/yr. The radiation levels in Pokhara, the most populated city of the western development region of Nepal, were found to be within the secure limit for areas of the normal background recommended by the International Commission on Radiological Protection (ICRP) (1 mSv/yr). Further, the current result was compared with the previous study of annual effective dose rate measured in Kathmandu city. Comparable value of the average annual effective dose rate in Pokhara and Kathmandu was obtained.

Doğu Karadeniz Bölgesinde kozmik ışın kaynaklı yıllık etkin doz dağılımının belirlenmesi

In this study, annual effective dose rate distribution due to cosmic radiation, which constitutes an important part of natural radiation, was mapped in spatial pixels for three provinces in the Eastern Black Sea region (Artvin, Rize and Trabzon). Cosmic ray-induced annual effective dose calculations were performed based on latitude and altitude changes with EXPACS, an excel-based program. Besides, the effect of cosmic radiation on the population living in the study area was determined. For the entire study area, it was calculated the average effective dose rate from Cosmic radiation as 0.65 mSv y-1 and range as (0.33-1.72) mSv y-1. The average annual collective effective dose rate was determined approximately 508 person-Sv y-1. Besides, the population-weighted average annual effective dose rates were obtained as 449, 376 and 370 for Artvin, Rize and Trabzon provinces, respectively.

Estimation of background radiation levels and associated health risks in mineral rich district Chiniot, Pakistan

The mineral extraction activities may disturb the natural radioactivity, therefore current study aims to generate baseline data of natural radionuclides and anthropogenic 137Cs before the start of industrial activities. Gamma spectrometry and gross alpha and beta counting systems were used for activity measurement in environmental samples. In soil, the mean activity of 232Th, 226Ra, 40K and 137Cs were determined as 79 (66–117), 47 (34–80), 823 (602–1159) and 1.3 (1.1–4.5) Bq kg−1, respectively. The average annual effective dose rate (128.7 µSv h−1) in the study area was twice higher than world’s average value. Indoor hazard index was greater than unity at two places; therefore, proper ventilation is proposed during construction.

Assessment of radioactivity levels in coal and coal ash in Kiwira coal mine using gamma-ray spectrometry

This study aimed to assess the radioactivity levels and associated dose rates from the naturally occurring radionuclides 226 Ra, 232 Th and 40 K in coal and coal ashes at Kiwira coal mine. The radioactivity of 40 representative coal, fly ash samples were measured using gamma spectroscopy of the Tanzania Atomic Energy Commission (TAEC) in Arusha, Tanzania. The activity concentrations of 226 Ra, 232 Th and 40 K in coal and coal ashes from Kiwira were higher by several orders of magnitude than their worldwide average values. The calculated radium equivalent activity, the air absorbed dose rate, external hazard index and the average annual effective dose rate in fly ashes were 1335 ± 60 Bq kg -1 , 610 ± 29 nGy h -1 , 4 ± 0.4, 738 ± 52 µSv y -1 which were higher than the international recommended values of 370 Bq kg -1 , 57 nGy h -1 , and 70 µSv y -1 for fly-ashes respectively. The results provide information for the radiation protection when the coal and its by-products in the vicinity of Kiwira coal field is used. The data can be used by the authorities to design an appropriate method for handling wastes and implement intervention measures to protect the miners, the public as well as the environment. Keywords: Coal, fly ash, soil, radioactivity, gamma-ray spectrometry

Risk assessment of human exposure to Ra-226 in oil produced water from the Bakken Shale

Unconventional oil production in North Dakota (ND) and other states in the United States uses large amounts of water for hydraulic fracturing to stimulate oil flow. Most of the water used returns to the surface as produced water (PW) containing different constituents. Some of these contents are total dissolved solids and radionuclides. The most predominant radionuclide in PW is radium-226 (Ra-226) of which level depends on several factors including the content of certain cations. A multivariate regression model was developed to predict Ra-226 in PW from the Bakken Shale based on the levels of barium, strontium, and calcium. The simulated Ra-226 activity concentration in PW was 535 pCi/L supporting extremely limited actual data based on three PW samples from the Bakken (527, 816, and 1210 pCi/L). The simulated activity concentration was further analyzed by studying its impact in the event of a PW spill reaching a surface water body that provides drinking water, irrigation water for crops, and recreational fishing. Using food transfer factors found in the literature, the final annual effective dose rate for an adult in ND was estimated. The global average annual effective dose rate via food and drinking water is 0.30 mSv, while the predicted dose rate in this study was 0.49 mSv indicating that there is potential risk to human health in ND due to Ra-226 in PW spills. This predicted dose rate is considered the best case scenario as it is based on the simulated Ra-226 activity concentration in PW of 535 pCi/L which is close to the low end actual activity concentration of 527 pCi/L.

Ardahan ili ve çevresindeki toprak örneklerindeki ortalama etkin dozun değerlendirilmesi için doğal radyoaktivitenin analizi

In this study, the distribution of natural radionuclides in surface soils in Ardahan province has been determined. The activity concentrations of 238 U, 232 Th, 40 K and 137 Cs in 35 soil samples collected from the Ardahan city and its surrounded districts were measured through NaI (Tl) gamma spectrometry. The average activities of the samples were determined to be 29.9±6.2, 36.7±6.8 and 435.1±23.9 Bq kg -1 for the natural radionuclides 238 U, 232 Th and 40 K, respectively. For the fission product 137 Cs, the average activity of the samples was assigned to be 15.5±0.8 Bq kg -1 . The average outdoor gamma dose rate (terrestrial and cosmic) and also the average annual effective dose rate in air due to the presence of radionuclides in 35 soil samples were obtained as 56.3±8.7 nGy h -1 and 69.0±6.7 µSv y -1 , respectively. This research showed a clear correlation between the altitude and the natural radionuclides. The results obtained for Ardahan city centrum and its districts were presented graphically and compared with the world average values and those of Turkey.

RADIOACTIVITY LEVELS AND DOSE RATES FROM ROCKS IN SELECTED MINING AREAS AND QUARRIES IN EASTERN UGANDA

The aim of this study was to determine the radioactivity levels and dose rates due to natural radionuclides in rocks from selected mining areas and quarries in Eastern Uganda. 60 rock samples collected from six mines and quarries were analyzed using a NaI gamma detector. The specific activities of 238 U, 232 Th and 40 K in the samples were measured, the gamma dose rate and annual effective dose outdoor were determined. The specific activities ranged from 13.95±0.31 to 698.02±3.38 Bq kg -1 for 238 U, 98.68±1.30 to 2397.78±19.64 Bq kg -1 for 232 Th, and 45.97±2.48 to 2183.80±17.89 Bq kg -1 for 40 K. The absorbed dose rates were calculated and the values obtained at all sites are above the world average of 59 nGy h -1 . The annual effective dose rate outdoor for all the sites ranges from 0.30 to 1.37 mSv y -1 . The average annual effective dose rate outdoor for some areas are below 1.00 mSv y -1 , the lowest permissible limit set by the International Commission on Radiation Protection (ICRP); while other sites have the annual effective dose rates higher than unity which suggests a health risk to the inhabitants of the areas. Therefore, the National Environmental Management Authority (NEMA) should monitor the disposal of radioactive wastes from the mines in this region for human safety.

Measurement of Gamma Radiation in an Automobile Mechanic Village in Abuja, North Central, Nigeria

Environmental radiation measurement was carried out in an automobile mechanic village, Apo, Abuja, Nigeria. An in-situ measurement approach was adopted using RDS-200 Universal Survey Meter and a handheld Global Positioning System (Garmin GPS 76S) equipment. It was observed that the dose equivalent varied from 0.04 μSv/h to 0.22 μSv/h with a mean of 0.10± 0.03 μSv/h which is below the standard background radiation of 0.133 μSv/h The study also revealed that the average annual effective dose rate is approximately 0.20±0.06 mSv/yr which is lower than the value of 1.0 mSv/yr averaged over five consecutive years according to the dose limit placed by the Basic Safety Standards (BSS) SCHEDULE II and the International Commission on Radiological Protection (ICRP) REPORT 60. This indicates that the automobile technicians, craftsmen and the people living and working within the area are safe and are not exposed to high doses of radiation as a result of activities in the Apo Automobile Mechanic Village. Keywords : Radiation Measurement; Apo Automobile Mechanic Village; Background Radiation; DoseEquivalent; Annual Effective Dose; Automobile Technicians

A Study on Natural Radioactivity in Khewra Salt Mines, Pakistan

The Khewra Salt Mines, the second largest salt mines in the world, are located 160 km south of Islamabad, the capital of Pakistan. Around 1000 workers are involved in the removal of salt from these mines. More than 40,000 visitors come annually to see the mines. The visitors and workers are directly exposed to the internal and external radiological hazards of radon and gamma rays in these mines. The general public is affected by the intake of the salt containing the naturally occurring radionuclides. Therefore the concentration of radon (²²²Rn) in the Khewra Salt Mines and activity concentrations of the naturally occurring radionuclides in the salt samples from these mines were measured. Both active and passive techniques were employed for the measurement of radon with Radon Alpha Detector (RAD-7) and SSNTD respectively. The concentration of ²²²Rn was 26 ± 4 Bq m⁻³ measured by the active method while 43 ± 8 Bq m⁻³ was measured by the passive method. The activity concentration of the radionuclides was measured using gamma ray spectrometry with HPGe detector. The mean activity of ⁴⁰K in salt samples was found to be 36 ± 20 Bq kg⁻¹ and the concentration of ²²⁶Ra and ²³²Th in the salt samples was below the detection limits. Gamma radiation hazard was assessed in terms of the external gamma dose from salt slabs and the rooms made of salt and the annual effective dose due to gamma radiation. The exposure to radon daughters, annual effective dose and excessive lifetime cancer risk due to radon in the mines were estimated. The mean annual effective dose due to an intake of ⁴⁰K from the salt was calculated as 20.0 ± 11.1 µSv, which is lower than the average annual effective dose rate of 0.29 mSv, received by the ingestion of natural radionuclides. Due to the low concentration values of primordial radionuclides in the salt and radon ²²²Rn) in the mines, a 'low level activity measurement laboratory' is suggested to be established in these mines.

Measurement of Gamma Radiation in Automobile Mechanic Workshops in an Area of Benin City, Nigeria

Environmental radiation measurement was carried out in several automobile mechanic workshops within Ugbowo area of Benin-City, Edo State, Nigeria. A Digilert 50 Nuclear Radiation monitor was used to ascertain the level of radiation to which these workers are daily exposed. The study revealed that the average annual effective dose rate from these sites is approximately 0.40 mSv/yr which is lower than the value of 1.0 mSv/yr averaged over five consecutive years according to the dose limit placed by the Basic Safety Standards (BSS) SCHEDULE II and the International Commission on Radiological Protection (ICRP) REPORT 60. However, the external background ionizing radiation exposure within the sites investigated varied between 0.1272 and 0.01411 mR/hr with an average of 0.01314 ± 0.000658 mR/hr in the locality which is relatively higher than the standard background radiation of 0.011 mR/hr recommended by the US Nuclear Radiation Commission. This level of background radiation seems to suggest that there is a possibility of the existence of radio nuclides within the area.

Levels of 232Th activity in the South Adriatic Sea marine environment of Montenegro

232Th activities in the South Adriatic Sea-water, surface sediment, mud with detritus, seagrass (Posidonia oceanica) samples, and the mullet (Mugilidae) species Mugil cephalus, as well as soil and sand from the Montenegrin Coast, were measured using the six-crystal spectrometer PRIPYAT-2M, which has relatively high detection efficiency and a good sensitivity, and allows a short acquisition time, and measuring samples of any shape, without preliminary preparation and calibration measurements for different sample geometries. An average 232Th activity concentration in surface soil layer is found to be 40.33 Bq kg−1, while in sand—4.7 Bq kg−1. The absorbed dose rate in air due to 232Th gamma radiation from surface soil layer ranged from 11.76 to 63.39 nGy h−1, with a mean of 24.06 nGy h−1. Corresponding average annual effective dose rate has been found to be 0.03 mSv y−1. The absorbed dose rates due to the thorium gamma radiation in air at 1 m above sand surface on the Montenegrin beaches have been found to be from 0.41 to 9.08 nGy h−1, while annual effective dose rates ranged from 0.0005 to 0.011 mSv y−1. 232Th activity concentration in seawater ranged from 0.06 to 0.22 Bq L−1, as in the mullet (Mugil cephalus) whole individuals from 0.63 to 1.67 Bq kg−1. Annual intake of 232Th by human consumers of this fish species has been estimated to provide an effective dose of about 0.003 mSv y−1.