mSv Year Research Articles

Estimation of the radiation dose equivalent for the hypothetical submergence of a sea-transport package of low-level radioactive waste

ABSTRACTJapanese Electric Power Utilities plans to transport low-level radioactive waste (LLW) in CSD-C (36 canisters) and CSD-B packages (10 canisters) by sea from France to Japan. In this study, we carried out assessments of the dose to the public from a hypothetical release of radioactive materials from submerged LLW packages into the sea. The estimated dose equivalents from the CSD-C and CSD-B packages were 2.8 × 10−8 and 7.9 × 10−9 mSv year−1, respectively, for the near shore case. For the deep sea case, the estimated dose equivalents were 8.6 × 10−8 and 5.8 × 10−8 mSv year−1, respectively. These estimated results were much smaller than those found in a previous study of Type-B packages (spent fuel, high level waste, and mixed oxide fuel) and the ICRP recommendation (1 mSv year−1).

Assessment of natural radioactivity and associated radiation hazards in sand building material used in Douala Littoral Region of Cameroon, using gamma spectrometry

Twenty-four sand samples were collected from different sand quarries from Douala Littoral Region (Wouri, Dibamba, Mungo and Docteur Anse rivers and Atlantic Sea) along the Guinea Golf. These samples were investigated using gamma-ray spectrometry system. Highest values of 226Ra, 232Th and 40K measured specific activities expressed in Bq Kg−1 units were, respectively, 146.7 (in Youpoue–Bamenda 2) 102.9 (in Village 1) and 928 (in Northern Akwa 6) while the lowest values were found to be, respectively, 11.8 (in Northern Akwa 6), 8.0 (in Bonaberi–Bonamikano 4) and 54.0 (Youpoue 3). The potential radiological hazards parameters were assessed by calculating successively radium equivalent activity (Raeq), outdoor absorbed gamma dose rate (D out), annual effective dose rate, internal hazard (H in) and external hazard (H ex) indices and alpha and gamma index from using those sand in the construction of dwellings and large buildings. Results obtained show that annual dose absorbed by inhabitants due to sand construction use in Douala is below 1.0 mSv year−1. Therefore, most of the types of sands studied and incorporated in constructions appear to be safe as building material. The outputs from this research will be useful to assess the radiation hazards of sand building material in humans and to initiate a sand database together with a radiological map of the area at stake.

Radiocaesium transfer from forest soils to wild edible fruits and radiation dose assessment through their ingestions in Czech Republic

ABSTRACTDue to the Chernobyl nuclear power plant accident in 1986, the environment of forest ecosystems is still contaminated by radiocaesium (137Cs). Currently the average surface soil activity of 137Cs is 3.87 kBq m−2 in the Czech Republic. Depending on the soil properties of the sample locality, the 137Cs content in selected edible forest fruits and related radiocaesium soil-to-fruit transfer was analysed. In addition, radiation doses through ingestion were estimated with regards to the potential health risk caused by consumption of the fruits. Fruits (blueberry, rowanberry, blackberry and raspberry) and soil samples were collected in some locations of the Jeseníky Protected Landscape Area (PLA), the north-eastern mountains of the Czech Republic most severely contaminated with radiocaesium (137Cs). The average aggregated transfer coefficient (TFag) for radiocaesium (137Cs) reached values ranging from 2.73 × 10−5 to 2.20 × 10−2 m2 kg−1. The values of TFag correlated with the soil reaction, with the content of humus and with the content of clay particles in the soil of the sample areas, that is, r = –0.90 (p < 0.001), r = 0.81 (p < 0.001) and r = –0.68 (p < 0.01), respectively. Only the soil reaction pH (KCl) had an effect on TFag (p < 0.01). The highest radiation dose which the average Czech consumer would receive after consumption of the fruits was calculated as 1.78 × 10−2 mSv year−1, and such a dose of radiocaesium should not present a serious health problem.

Transfer Factors and Effective Dose Evaluation Due to Natural Radioactivity in Staple Food Grains from the Vicinity of Proposed Nuclear Power Plant

This study focused on quantification of radioactivity concentration of naturally occurring radioactive materials 40K, 226Ra and 232Th in most staple food grain i.e. wheat of the study area using gamma spectrometry for two years. 40K, 226Ra and 232Th activities were detectable in most of the wheat grain samples and ranged 111.3–245.7, 226Ra (41 ± 1.6 Bq kg−1) > 232Th (32.3 ± 1.2 Bq kg−1) and comparable to the corresponding levels obtained worldwide. The geometric mean transfer factors of studied NORMs in wheat grains were in order: 40K (0.371 ± 0.07) > 226Ra (0.003 ± 0.002) > 232Th (0.001 ± 0.001). Significant positive dependencies of transfer factors of 40K, 226Ra and 232Th in wheat grains were observed with total organic carbon content of soil. Estimated annual effective doses from ingestion of the wheat were 1.37E−01 mSv year−1 for 40K, 4.14E−03 mSv year−1 for Ra226 and 1.10E−03 mSv year−1 for 232Th, well under the permissible cumulative global average.

Measurement of natural environmental radioactivity and estimation of population exposure in Bihac, Bosnia and Herzegovina

This work presents measurements of activity concentrations and estimation of population exposure from the naturally occurring radionuclides 238U, 232Th, and 40K in various surface soil formations of Bihac city. From the measured gamma-ray spectra, activity concentrations were determined for 238U, 232Th and 40K with respective average values of 54 ± 3 Bq kg−1, 41 ± 1 Bq kg−1 and 367 ± 17 Bq kg−1. Calculation of the absorbed dose rates for soil had average value of 65.10 nGy h−1. The corresponding annual effective dose equivalent indoors had an average value of 0.319 mSv year−1, and outdoors 0.080 mSv year−1.

Assessment of natural radioactivity in cements used as building materials in Turkey

The radioactivity concentrations of 226Ra, 232Th and 40K in 42 samples from different types of cements produced in Turkey were measured using gamma-ray spectrometer. The determined values were 18–143 Bq kg−1 (226Ra), 5–66 Bq kg−1 (232Th) and 142–540 Bq kg−1 (40K). Additionally, the calculated radiological hazard parameters such as absorbed dose rate, annual effective dose, radium equivalent activity, the external hazard, activity and alpha indices were found to be in the range of 38–158 nGy h−1, 188–776 µSv year−1, 41–182 Bq kg−1, 0.11–0.49, 0.15–0.65 and 0.09–0.71, respectively. Finally, the results were statistically evaluated and compared with the reported data in other countries and the international standard values given by European Commission and UNSCEAR.

Occurrence of natural radioactivity and corresponding health risk in groundwater with an elevated radiation background in Juban District, Yemen

This study aims to investigate the occurrence of natural radiation in groundwater with an elevated background level in Juban District, Yemen, and to assess the corresponding health risk. The mean concentrations of U, Th, and K in groundwater were 11.25, 0.15, and 17.35 mg l−1, respectively. The mean activity concentrations of 226Ra, 228Ra, and 40K were 94, 216, and 3306 mBq l−1, respectively. 65 % of the groundwater samples were above the WHO guidance level for 228Ra in water. The maximum concentrations of 226Ra, Th, and 228Ra were found around the fault zones in the basement aquifer while the concentrations of U increase down-gradient of Juan District. The principal factors controlling the occurrence and concentrations of radionuclides are aquifer type, leaching behaviour, characteristics of fracture systems, salinity, and water flow path. The annual effective doses due to ingestion of the water were estimated for infant and adult groups. The mean annual effective dose for infants was 1.97 mSv year−1 which is almost twenty times the WHO guideline level for drinking water. The ingestion dose deduced for adults and infants is dominated by 228Ra, where the average contribution from 228Ra in infants amounted to 90 % and in adults 76 %.

Evaluation of radiological hazards associated with the uses of marble and ceramic as decorative building materials in Egypt

Radon concentrations of 20 samples of marble and ceramic were measured using AlphaGuard and varied from 36.02 ± 2.89 to 614.59 ± 99.40 Bq m−3 with a mean value of 139.12 ± 11.44 Bq m−3. Radon emanation coefficient and exhalation rate were also calculated. Moreover, radiation dose of released radon was calculated using two models, showing good agreement. Its value was varied from 6.3 ± 0.52 to 76.23 ±3.82 μSv year−1 with a mean value of 23.20 ± 1.54 μSv year−1. The results implied that radiation dose was less than safety limit of 1 mSv year−1. Therefore, the selected marble and ceramic types could be safely used as decorative building materials.

Spatial distribution of natural γ radiation exposure and its relationship to soil types

An extensive survey of natural γ radiation dose rate levels was measured throughout the Melaka State, Malaysia. The main objective of the present study is to verify the influence of different soil types γ radiation exposures in air using statistical analyses. One-way analysis of variances ANOVA and post hoc test using Fisher’s least significant difference (LSD) were used to test the probability of significance difference between the dose rates and soil types. The survey involved 541 measurement points of terrestrial gamma radiation dose rates in an area of 1650 km2 which covers five major soil groups based on six FAO/UNESCO soil orders. The spatial dose distributions and descriptive statistics of all measured γ radiation dose rates are presented. It has the mean value of 183 nGy h−1. The significance test using ANOVA shows that all dose rates for four soil groups were significantly different from each other with p sig. value <0.005 and the f-ratio lies in the rejection region, f-critical (Fα,(2, n−2)). The post hoc test using Fisher’s LSD shows that there are two main groups of dose rates with each range 152–175 nGy h−1 and 218–233 nGy h−1. These two classification groups indicated the low and high range of dose rates due to the different soil groups derived from different parent rocks. An estimation of average annual effective dose equivalent to the individual in the study area was 1.12 mSv year−1. For granitic soil region, the public is expected to receive slightly high effective dose of 2 mSv year−1. The statistical significance test shows that the soil types significantly influenced the γ radiation exposures received by the public on the ground level.

Determination of 226Ra, 232Th, 40K, 235U and 238U activity concentration and public dose assessment in soil samples from bauxite core deposits in Western Cameroon

Determination of activity concentrations in twenty five (25) soil samples collected from various points in bauxite ore deposit in Menoua Division in Western of Cameroon was done using gamma spectrometry based Broad Energy Germanium (BEGe6530) detector. The average terrestrial radionuclides of 40K, 226Ra, 232Th, 235U and 238U were measured as 671 ± 272, 125 ± 58, 157 ± 67, 6 ± 3 and 99 ± 69 Bq kg−1, respectively. The observed activity concentrations of radionuclides were compared with other published values in the world. The outdoor absorbed dose rate in air varied from 96.1 to 321.2 nGy h−1 with an average of 188.2 ± 59.4 nGy h−1. The external annual effective dose rate and external hazard index were estimated as 0.23 ± 0.07 mSv year−1 for outdoor, 0.92 ± 0.29 mSv year−1 for indoor and 1.13 for the external hazard index, respectively. These radiological safe parameters were relatively higher than the recommended safe limits of UNSCEAR. Consequently, using of soil as building material might lead to an increase the external exposure to natural radioactivity and future applications research need to be conducted to have a global view of radioactivity level in the area before any undergoing bauxite ore exploitation.

Quantification and assessment of health risk due to ingestion of uranium in groundwater of Jammu district, Jammu &amp; Kashmir, India

The uranium content in groundwater being used for drinking purposes in Jammu district, Jammu & Kashmir, India has been measured by using LED fluorimetric technique to determine associated carcinogenic and non-carcinogenic health risk for inhabitants of this area. Uranium concentration and age dependent ingestion dose varied from 0.18 to 20.81 µg l−1 and 0.16 to 42.46 µSv year−1, being well within the recommended limits suggested by different health agencies of the world. The physico-chemical properties (TDS, EC and pH) have also been measured and correlated with obtained uranium concentration. Hence, the groundwater can be considered to be safe for consumption by public.

Indoor radon measurement in Izmir Province, Turkey

ABSTRACTIn 2013, an extensive study was performed in a total of 117 locations in Izmir province and indoor radon levels were measured using the alpha track etch integrated method with LR-115 detectors. As the maps are more practical to interpret the results of radiological survey, the distributions of indoor 222Rn activities in four most densely populated districts of Izmir were mapped in detail. It is seen that the estimated average radon concentration level (210 Bq m−3) determined in Izmir province was almost three times higher than the mean value for Turkey (81 Bq m−3). Exposed annual effective dose equivalents for Izmir province were estimated in the range of 0.7 to 12.3 mSv year−1 with a mean of 5.3 mSv year−1. In this study, it is pointed out that indoor radon concentration was affected by the age of the building and height above the ground.

Radiolead 210Pb and 210Po/210Pb activity ratios in calcium supplements and the assessment of their possible dose to consumers

ABSTRACTThis paper presents the results of pioneer study of the most popular calcium supplements as a potential additional source of radiolead 210Pb in human diet. The analyzed calcium pharmaceutics contained organic or inorganic calcium compounds; some came from natural sources as mussels' shells, fish extracts, or sedimentary rocks. The idea was to investigate the naturally occurring 210Pb activity in different calcium supplements and calculate the annual effective radiation dose from radiolead 210Pb decay in consumed calcium supplement. The results showed 210Pb concentrations in natural origin calcium supplements (especially sedimentary rocks) were significantly higher. The highest 210Pb activity concentrations were determined in mineral tablets made from dolomite – 2.97 ± 0.18 mBq g−1, while the lowest was observed in organic calcium compounds – both calcium lactate – 0.08 ± 0.01 and 0.13 ± 0.01 mBq g−1. The highest annual radiation dose from 210Pb taken with 1 tablet of calcium supplement per day was calculated for soluble calcium lactate sample – 1.19 ± 0.03 µSv year−1, while the highest annual radiation dose from 210Pb taken daily with 1 g of pure Ca for dolomite – 5.57 ± 0.34 µSv year−1.

Radiation Monitoring Results from the First Year of Operation of a Unique Ambulance-based Computed Tomography Unit for the Improved Diagnosis and Treatment of Stroke Patients.

When a blood clot blocks the blood supply to the brain or when a blood vessel bursts, resulting in brain cell death, the medical condition is referred to as a "stroke." Stroke is a main cause of death worldwide and is a common cause of disability. A common form of stroke, called ischemic stroke, is when blood flow to the brain is decreased. Clinical research has revealed that treatment within the very first hours of symptom onset is key for ischemic stroke with recanalization of occluded arteries by thrombolysis with alteplase. Computed tomography (CT) is one of the diagnostic tools used to determine if this treatment path is appropriate. To determine if health outcomes of possible stroke patients can be improved by decreasing the time from symptom presentation to treatment, the first mobile stroke ambulance unit in the United States was deployed by The University of Texas Health Science Center at Houston (UTHealth) in 2014, equipped with a computed tomography imaging system. The mobile stroke unit shortens the time to treatment for stroke patients by allowing pre-hospital treatment. Having completed its first year of operation, radiation-monitoring data describing the doses delivered to various entities have been characterized. The CT operator's cumulative deep dose equivalent for 1 y of operation was 1.14 mSv resulting from the care of 106 patients. Area monitors were deployed and measurements performed demonstrating that general public doses did not exceed 0.02 mSv h⁻¹ or 1.0 mSv year.

238U and 232Th concentrations measured in different medical drugs by using solid-state nuclear track detectors and resulting radiation doses to the skin of patients

Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres. To explore the exposure pathway of 238U and 232Th and their decay products on the skin of patients, these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors (SSNTDs).The measured concentrations range of 238U and 232Th in the medical drug samples of interest vary from (4.3 ± 0.3) to (11.1 ± 0.7) mBq l−1 and (0.49 ± 0.03) to (1.3 ± 0.1) mBq l−1, respectively. A new dosimetric model, based on the concept of specific alpha-dose and alpha-particle residual energy, was developed for evaluating radiation doses to skin following the application of different medical drugs by patients. The maximum total equivalent effective dose to skin due to the 238U and 232Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year−1 cm−2.

Occupational dose constraints for the lens of the eye for interventional radiologists and interventional cardiologists in the UK.

The International Commission on Radiological Protection (ICRP) has recommended a 20 mSv year(-1) dose limit for the lens of the eye, which has been adopted in the European Union Basic Safety Standards. Interventional radiologists (IRs) and interventional cardiologists (ICs) are likely to be affected by this. The effects of radiation in the lens are somewhat uncertain, and the ICRP explicitly recommend optimization. Occupational dose constraints are part of the optimization process and define a level of dose which ought to be achievable in a well-managed practice. This commentary calls on the professional bodies to review a need for national constraints to guide local decisions. Consideration is given to developing such constraints using maximum expected doses in high-workload facilities with good radiation protection practices and application of a factor allowing for attenuation by lead glasses (LG). Doses are based on a Public Health England survey of eye dose in the UK. Maximum expected doses for ICs are approximately 21 mSv year(-1), neglecting LG. However, the extent of IR exposure is not yet fully known, and further evidence is required before conclusions are drawn. A Health and Safety Laboratory review of LG established a conservative dose reduction factor of 3 for models available in 2012. Application of this factor provides a dose constraint of 7 mSv year(-1) to the eye for ICs. To achieve this constraint, those employers with the most exposed ICs will have to provide and ensure the correct use of a ceiling-suspended eye shield and LG.

Natural and fallout radioactivity levels and radiation hazard evaluation in soil samples

The present study aims to obtain the baseline data on natural and fallout radioactivity and to evaluate radiation hazards caused by ionizing radiation emitted from 226Ra, 232Th, 222Rn, 40K and 137Cs in surface soil samples collected from Mersin province and Akkuyu nuclear power plant region. The activity concentrations of 226Ra, 232Th, 40K and 137Cs were measured using a gamma spectrometer with HPGe detector. The activity concentrations of 226Ra, 232Th, 40K and 137Cs varied from 14.1 ± 0.7 to 65.4 ± 2.9, 12.0 ± 0.8–51.7 ± 2.1, 172.2 ± 15.8–511.1 ± 37.8 and <MDA to 86.2 ± 1.4 Bq kg−1, respectively. The average concentrations of radon in soil and air were estimated as 23.9 kBq m−3 and 76 Bq m−3. The radiological parameters such as absorbed gamma dose rate in outdoor air (DRout), annual effective dose rate from external exposure (EExt), annual effective dose rate from inhalation of radon (EInh) and lifetime cancer risk (LTCR) were calculated to evaluate radiological hazards. The average values of DRout, EExt, EInh and LTCR were found to be 51 nGy h−1, 62 μSv year−1, 715 μSv year−1 and 2.2 × 10−4, respectively.

The potential health hazards of chronic exposure to low-dose natural radioactivity in Terengganu, Malaysia

Measurement of terrestrial gamma radiation dose (TGRD) rate and activity concentrations of naturally occurring radionuclides in environmental media such as soil and air play an important role in the setting national average permissible doses to members of public. Malaysia is planning to add nuclear energy to its national electricity grid; hence the knowledge of the levels of exposure to natural background radioactivity is important for policies and law making with regards to radiological protection of both human and the environment. The aim of this work was to measure the variation of background radiation with respect to geological formations of Terengganu (Malaysia) and assess the potential health hazards that are associated with the chronic exposure to natural radiation in the area. Ludlum 19 micro survey meters with NaI[Tl] detectors and HPGe gamma ray spectrometer were used for in situ TGRD and laboratory analysis, respectively. The measured TGRD rates ranged from 35 to 340 nGy h−1 with mean value of 150 nGy h−1 and the annual effective dose to population was 0.92 mSv year−1. The mean (range) activity concentrations of 226Ra, 232Th, and 40K in the soil samples were 79 ± 3 (20 ± 1–151 ± 5) Bq kg−1; 84 ± 3 (8 ± 1–182 ± 6) Bq kg−1; and 545 ± 55 (47 ± 5–1056 ± 107) Bq kg−1, respectively. Upon comparing these values with the world averages for specific activities of 226Ra, 232Th and 40K (i.e. 33, 36 and 474 Bq kg−1 for 226Ra, 232Th and 40K respectively), It is revealed that the mean activity concentrations of 226Ra and 232Th in the soil of Terengganu are higher than the world averages by a factor of two. The mean activity concentration of 40K in the soil of Terengganu is ~15 % higher than the world average. Acid intrusive geological formation (due to the granite composition from igneous rocks), which is the most dominant in the state was found to contained higher mean TGRD values as well as 226Ra and 232Th concentration this was consistent with some previous studies.

Dose assessments from the measured radioactivity in soil, rock, clay, sediment and food crop samples of an elevated radiation area in south-western Nigeria

Activity concentrations of 40K, 226Ra and 232Th were measured in five different environmental matrices and food crops collected from some elevated radiation areas of Sikiti south-west Nigeria to estimate the radiation dose incur by the population. In situ gamma dose rates were also measured at every collection point for comparison. The activity concentrations of the various radionuclides obtained for rock samples collected from mining sites were generally higher than those of other matrices except 226Ra that is relatively low in rocks of the study area. Radiological hazard indices were estimated to assess the harmful effects of gamma radiation to the population dwelling in the area. The activity concentrations and the estimated radiological parameters were comparable to values obtained in elevated radiation areas around the world. The mean in situ measured absorbed dose rate is 232.8 ± 49.8 nGy h−1, which is far greater than the worldwide mean outdoor value of 60 nGy h−1. The total annual effective ingestion dose obtained in this study is 339.4 µSv year−1, which is higher than the 290 µSv year−1 reported as the world average value. Also, the total annual effective dose due to external and internal gamma radiation exposures in the study area is 1.83 mSv year−1, which is greater than the 1 mSv year−1 recommended by ICRP for members of the public. It can therefore be concluded that the radiological risks to the general population from gamma radiation due to natural radionuclides in the area are significant.

210Ро in black and green teas

The 210Ро content in various grades of tea sold in St. Petersburg shops was determined, and the effective annual dose of internal irradiation from 210Ро at daily tea drinking was estimated. As shown by α-ray spectrometry, the activity concentration of 210Ро in tea leaves varies from 1.1 to 25 Bq kg–1. The 210Po content in black teas is, on the average, 1.7 times higher than in green teas. This difference is accounted for by specific features of processes for the production of black and green teas. From 1.5 to 56% of 210Ро passes into aqueous extracts. Despite higher polonium content in black teas, the amount of 210Po extracted from green teas is, on the average, 6.3 times higher than that extracted from black teas. This effect may be associated with the formation of water-soluble organic polonium compounds on the surface of tea leaves in the course of tea processing. The effective annual dose of internal irradiation from polonium at daily use of 10 g of dry tea is estimated at 0.8–9.5 μSv year–1 depending on the tea grade, or 0.5–5.8% of the average annual dose of irradiation of the Russian Federation population from the sum of the nuclides (210Pb, 210Po, 228Rа, 226Rа, etc., except 40K) getting into a human body with food and water.