Showing papers in "Journal of Radiological Protection in 2008"
TL;DR: These new recommendations take account of the latest biological and physical information and consolidate the additional guidance provided by ICRP since 1990 and provide confidence that the system of protection established by and large in its present form several decades ago has reached a certain level of maturity.
Abstract: This paper provides a review of the 2007 recommendations of the International Commission on Radiological Protection (ICRP). These new recommendations take account of the latest biological and physical information and consolidate the additional guidance provided by ICRP since 1990. The changes to the scientific data are not substantial. ICRP has retained its fundamental hypothesis for the induction of stochastic effects of linearity of dose and effect without threshold and a dose and dose-rate effectiveness factor (DDREF) of 2 to derive nominal risk coefficients for low doses and low dose rates. While the overall detriment from low radiation doses has remained unchanged, ICRP has made adjustments to the values of the radiation and tissue weighting factors. In particular, the tissue weighting factor for breast has increased while that for gonads has decreased. There are some presentational changes to the system of protection. While ICRP has maintained the three fundamental principles--justification, optimisation of protection, and dose limitation-it has attempted to develop a more holistic approach to radiological protection covering all exposure situations--planned, existing and emergency--and all radiation sources, whether of natural or artificial origin. This approach should ensure that attention is focused on those exposures that can reasonably be controlled. It has also strengthened the principle of optimisation of protection with a particular emphasis on the use of constraints for planned exposure situations and reference levels for existing and emergency exposure situations. Dose constraints and reference levels are categorised into three bands which should assist in rationalising the many values of dose restrictions given in earlier ICRP publications. There are no changes to the dose limits. ICRP also indicates its intentions with respect to the development of further guidance on the protection of the environment. The fact that these new recommendations are more a matter of consolidation of previous ICRP recommendations and guidance should provide confidence that the system of protection established by and large in its present form several decades ago has reached a certain level of maturity. As such, no major changes to radiological protection regulations based on the 1990 recommendations should be necessary.
372 citations
TL;DR: A total of 183 samples of 20 different commonly used structural and covering building materials were collected from housing and other building construction sites and from suppliers in Ankara to measure the natural radioactivity due to the presence of (226)Ra, (232)Th and (40)K to assess the potential radiological hazard associated with these building materials.
Abstract: A total of 183 samples of 20 different commonly used structural and covering building materials were collected from housing and other building construction sites and from suppliers in Ankara to measure the natural radioactivity due to the presence of (226)Ra, (232)Th and (40)K. The measurements were carried out using gamma-ray spectrometry with two HPGe detectors. The specific activities of the different building materials studied varied from 0.5 +/- 0.1 to 144.9 +/- 4.9 Bq kg(-1), 0.6 +/- 0.2 to 169.9 +/- 6.6 Bq kg(-1) and 2.0 +/- 0.1 to 1792.3 +/- 60.8 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The results show that the lowest mean values of the specific activity of (226)Ra, (232)Th and (40)K are 0.8 +/- 0.5, 0.9 +/- 0.4 and 4.1 +/- 1.4 Bq kg(-1), respectively, measured in travertine tile while the highest mean values of the specific activity of the same radionuclides are 78.5 +/- 18.1 (ceramic wall tile), 77.4 +/- 53.0 (granite tile) and 923.4 +/- 161.0 (white brick), respectively. The radium equivalent activity (Ra(eq)), the gamma-index, the indoor absorbed dose rate and the corresponding annual effective dose were evaluated to assess the potential radiological hazard associated with these building materials. The mean values of the gamma-index and the estimated annual effective dose due to external gamma radiation inside the room for structural building materials ranged from 0.15 to 0.89 and 0.2 to 1.1 mSv, respectively. Applying criteria recently recommended for building materials in the literature, four materials meet the exemption annual dose criterion of 0.3 mSv, five materials meet the annual dose limit of 1 mSv and only one material slightly exceeds this limit. The mean values of the gamma-index for all building materials were lower than the upper limit of 1.
99 citations
TL;DR: In contrast to miners exposed to radon and radon decay products, for uranium mill workers exposed to uranium dusts and mill products there was no clear evidence of uranium-related disease.
Abstract: A cohort mortality study of workers engaged in uranium milling and mining activities near Grants, New Mexico, during the period from 1955 to 1990 was conducted. Vital status was determined through 2005 and standardised mortality ratio (SMR) analyses were conducted for 2745 men and women alive after 1978 who were employed for at least six months. Overall, mortality from all causes (SMR 1.15; 95% CI 1.07-1.23; n = 818) and all cancers (SMR 1.22; 95% CI 1.07-1.38; n = 246) was greater than expected on the basis of US mortality rates. Increased mortality, however, was seen only among the 1735 underground uranium miners and was due to malignant (SMR 2.17; 95% CI 1.75-2.65; n = 95) and non-malignant (SMR 1.64; 95% CI 1.23-2.13; n = 55) respiratory diseases, cirrhosis of the liver (SMR 1.79; n = 18) and external causes (SMR 1.65; n = 58). The lung cancer excess likely is attributable to the historically high levels of radon in uranium mines of the Colorado Plateau, combined with the heavy use of tobacco products. No statistically significant elevation in any cause of death was seen among the 904 non-miners employed at the Grants uranium mill. Among 718 mill workers with the greatest potential for exposure to uranium ore, no statistically significant increase in any cause of death of a priori interest was seen, i.e., cancers of the lung, kidney, liver, or bone, lymphoma, non-malignant respiratory disease, renal disease or liver disease. Although the population studied was relatively small, the follow-up was long (up to 50 yrs) and complete. In contrast to miners exposed to radon and radon decay products, for uranium mill workers exposed to uranium dusts and mill products there was no clear evidence of uranium-related disease.
67 citations
TL;DR: This review updates material prepared for the UK Government Committee Examining Radiation Risks from Internal Emitters (CERRIE) and also refers to the new recommendations of the International Commission on Radiological Protection (ICRP) and other recent developments.
Abstract: This review updates material prepared for the UK Government Committee Examining Radiation Risks from Internal Emitters (CERRIE) and also refers to the new recommendations of the International Commission on Radiological Protection (ICRP) and other recent developments. Two conclusions from CERRIE were that ICRP should clarify and elaborate its advice on the use of its dose quantities, equivalent and effective dose, and that more attention should be paid to uncertainties in dose and risk estimates and their implications. The new ICRP recommendations provide explanations of the calculation and intended purpose of the protection quantities, but further advice on their use would be helpful. The new recommendations refer to the importance of understanding uncertainties in estimates of dose and risk, although methods for doing this are not suggested. Dose coefficients (Sv per Bq intake) for the inhalation or ingestion of radionuclides are published as reference values without uncertainty. The primary purpose of equivalent and effective dose is to enable the summation of doses from different radionuclides and from external sources for comparison with dose limits, constraints and reference levels that relate to stochastic risks of whole-body radiation exposure. Doses are calculated using defined biokinetic and dosimetric models, including reference anatomical data for the organs and tissues of the human body. Radiation weighting factors are used to adjust for the different effectiveness of different radiation types, per unit absorbed dose (Gy), in causing stochastic effects at low doses and dose rates. Tissue weighting factors are used to take account of the contribution of individual organs and tissues to overall detriment from cancer and hereditary effects, providing a simple set of rounded values chosen on the basis of age- and sex-averaged values of relative detriment. While the definition of absorbed dose has the scientific rigour required of a basic physical quantity, the same is not true of the ICRP protection quantities equivalent and effective dose (i.e. those measured in sieverts). The ICRP quantities are intended for practical application in radiological protection and the choice of radiation and tissue weighting factors used in their calculation involves simplifying assumptions regarded as acceptable for this purpose. Best estimates of doses and risks to individuals and specific population groups may be calculated using ICRP biokinetic and dosimetric approaches, but would require the use of best available information on RBE and age-, sex- and population-specific risk factors. Consideration of uncertainties is important in applications such as the assessment of the probability of cancer causation for an individual and in estimating doses in epidemiological studies. While the ICRP system of protection does not take explicit account of uncertainties, an understanding of the various contributions to uncertainty can be seen to be of value when making judgments on the optimisation of protection.
66 citations
TL;DR: The present work deals with the radioactivity of samples of tin tailings collected from a mining site in Jos, Nigeria, using a gamma-ray spectrometer with a hyper-pure germanium detector to measure activity concentrations and in situ dose rates.
Abstract: The present work deals with the radioactivity of samples of tin tailings collected from a mining site in Jos, Nigeria The activity concentrations of the samples were measured using a gamma-ray spectrometer with a hyper-pure germanium detector In situ dose rates at the site were also measured using a precalibrated survey meter Potassium-40 was not detected in any of the studied samples The activity concentrations of (238)U and (232)Th ranged from 171 x 10(2) to 166 x 10(3) Bq kg(-1) and from 529 x 10(2) to 475 x 10(3) Bq kg(-1), with mean values of 722 x 10(2) and 168 x 10(3) Bq kg(-1), respectively The absorbed dose rates were between 40 and 363 microGy h(-1), with a mean value of 135 microGy h(-1), which is much higher than the world average of 006 microGy h(-1) for soil The calculated effective dose rates varied between 28 and 254 microSv h(-1), with a mean value of 94 microSv h(-1), whereas the effective dose rates obtained for the in situ measurement varied between 60 and 280 microSv h(-1) The annual gonadal dose equivalent was calculated as 924 mSv This is much higher than the world average dose equivalent rate to individuals from soil (030 mSv y(-1))
55 citations
TL;DR: Although the studies presently reported are uninformative on risks from tritium, a number of the occupationally exposed cohorts would be potentially informative, particularly if data were suitably combined.
Abstract: Tritium (3H) is a radioactive isotope of hydrogen. A number of factors combine to create a good deal of interest in the risks arising from exposure to tritium of both workers and members of the public. Tritium is ubiquitous in environmental and biological systems and is very mobile due to its occurrence as tritiated water. In this paper we systematically review epidemiological data relating to tritium exposure with a view to assessing the risk of such exposure using those studies that are potentially informative. The usefulness of the available studies of cancer and other adverse health effects in workforces and members of the general public is often impaired by a lack of tritium-specific dose data, low doses and small numbers of cases. A number of workforce studies have been identified in which tritium-specific individual doses have been estimated, although none of them, as presently reported, enable reliable inferences to be made on risks associated with exposure to tritium. In general, the available epidemiological studies on the offspring of radiation workers or on pregnancy outcome in areas subject to releases of tritium do not contain enough detail to estimate risks from tritium exposure. Although the studies presently reported are uninformative on risks from tritium, a number of the occupationally exposed cohorts would be potentially informative, particularly if data were suitably combined.
46 citations
TL;DR: In the present study, the distribution of (226)Ra, (232)Th and (40)K was measured in soil samples collected from different lithological units of the Thauldhar and Budhakedar regions of Garhwal Himalaya, India using gamma ray spectrometry.
Abstract: The exposure of human beings to ionising radiation from natural sources is a continuing and inescapable feature of life on earth. Natural radionuclides are widely distributed in various geological formations and ecosystems such as rocks, soil groundwater and foodstuffs. In the present study, the distribution of (226)Ra, (232)Th and (40)K was measured in soil samples collected from different lithological units of the Thauldhar and Budhakedar regions of Garhwal Himalaya, India. The collected soil samples were analysed using gamma ray spectrometry. The activity concentrations of the naturally occurring radionuclides (226)Ra, (232)Th and (40)K in these soil samples were found to vary from below detection level (BDL) to 131 +/- 18 Bq kg(-1), 9 +/- 6 to 384 +/- 53 Bq kg(-1) and 471 +/- 96 to 1406 +/- 175 Bq kg(-1), respectively. The distribution of radionuclides depends upon the rock formation and chemical properties within the earth. The activity concentrations vary widely depending on the sample origin. The external absorbed gamma dose rates due to (226)Ra, (232)Th and (40)K were found to vary from 49 to 306 nGy h(-1). The average radium equivalent activity from these soil samples was 300 Bq kg(-1).
45 citations
TL;DR: Results do not indicate an excess risk of leukaemia in young children living near French nuclear power plants.
Abstract: A recent study indicated an excess risk of leukaemia among children under the age of 5 years living in the vicinity of nuclear power plants in Germany. We present results relating to the incidence of childhood leukaemia in the vicinity of nuclear power plants in France for the same age range. These results do not indicate an excess risk of leukaemia in young children living near French nuclear power plants.
40 citations
TL;DR: It can be concluded that the long duration of refining activities does not seem to have affected radionuclide concentrations in the environment and the probability of occurrence of any health effects of radiation was judged low.
Abstract: Radioactivity measurements have been carried out using gamma-ray spectroscopy to determine the radionuclide concentrations in soil samples in the premises of the Warri Refining and Petrochemical Company located in the Niger Delta region of Nigeria and also in communities around it. The radionuclide contents of the crude oil and petroleum additives were also similarly determined. Results indicate that on the premises used by the company, the ranges of activity concentrations of 40K, 226Ra and 228Th in the soil samples were 261.3–932.3 Bq kg−1,<4.2–23.0 Bq kg−1 and<5.1–10.2 Bq kg−1, respectively. For the 13 villages studied, activity concentrations ranged from <17.2–766.3 Bq kg−1,<4.2–104.7 Bq kg−1 and<5.1–13.7 Bq kg−1, respectively, for 40K, 226Ra and 228Th. The lowest radionuclide concentrations were found in the crude oil relative to the petroleum additives. The highest outdoor effective dose rate obtained in the study was 47.5 µSv y−1 for the villages and 35.2 µSv y−1 within the company premises. These values are less than the world average outdoor value of 70 µSv y−1 given by UNSCEAR. Overall, it can be concluded that the long duration of refining activities does not seem to have affected radionuclide concentrations in the environment. Measurements also showed that the observed radiation dose rates did not vary significantly from the previously determined Warri City outdoor gamma radiation dose rates, for which the probability of occurrence of any health effects of radiation was judged low. The measurements, therefore, are interpreted to represent baseline radiometric data for future reference and research in the area.
34 citations
TL;DR: The measured specific activities and the derived quantities, hazard indices and radiation dose, have been compared with those given in the literature for these parameters.
Abstract: Granite is an igneous rock that contains natural radioactivity of primordial radionuclides. In Pakistan, granite is distributed in a vast area called the Ambela Granitic Complex (AGC) in North West Frontier Province (NWFP). Granite is a hard rock that exists in different colours and is used to decorate floors, kitchen counter tops, etc. The use of granite in a building as a decor material is a potential source of radiation dose; therefore, natural radioactivity has been measured in 20 granite samples of the AGC with an HPGe (high purity germanium) based gamma ray spectrometer. The average specific activities and their range (given in parentheses) for primordial radionuclides 40K, 226Ra and 232Th were 1218 (899?1927), 659 (46?6120) and 598?(92?3214)?Bq?kg?1, respectively. The measured activity concentrations were used for the assessment of hazard indices and radiation dose which were evaluated based on the permissible limits defined for these parameters. The measured specific activities and the derived quantities, hazard indices and radiation dose, have been compared with those given in the literature for these parameters.
34 citations
TL;DR: The baseline data will prove useful and important in estimating the collective dose near the new nuclear power plant under construction in Taiwan, and Analytical results demonstrate that no radiological anomaly exists.
Abstract: Activity concentrations and distributions of natural and man-made radionuclides in soil samples collected around nuclear power plant IV, Taiwan, were investigated for five years to assess the environmental radioactivity and characterisation of radiological hazard prior to commercial operation. The activity concentrations of radionuclides were determined via gamma-ray spectrometry using an HPGe detector. Data obtained show that the average concentrations of the (238)U and (232)Th series, and (40)K, were within world median ranges in the UNSCEAR report. The (137)Cs ranged from 2.46 +/- 0.55 to 12.13 +/- 1.31 Bq kg(-1). The terrestrial absorbed dose rate estimated by soil activity and directly measured with a thermoluminescence dosemeter (excluding cosmic rays), and the annual effective doses, were 45.63, 57.34 nGy h(-1) and 57.19 microSv, respectively. Experimental results were compared with international recommended values. Since the soil in this area is an important building material, the mean radium equivalent activity, external and inhalation hazard indices and the representative level index using various models given in the literature for the study area were 98.18 Bq kg(-1), 0.27, 0.34 and 0.73, respectively, which were below the recommended limits. Analytical results demonstrate that no radiological anomaly exists. The baseline data will prove useful and important in estimating the collective dose near the new nuclear power plant under construction in Taiwan.
TL;DR: It is demonstrated that, under the assumption of lognormally distributed data with outliers, a two stage approach to testing which first detects and removes outliers from the data and then applies the beta based method is most satisfactory from both a theoretical and empirical perspective.
Abstract: Radon risk maps have been produced in many countries using non-geologically based techniques utilising the lognormal and gamma distributions to display point estimates of the probability, PRL, that indoor radon levels will exceed a reference level. Recent work on updating radon maps in Ireland prompted an examination of various statistical issues associated with non-geologically based radon mapping techniques. The purpose of this paper is to compare existing techniques with a new theoretically unbiased model which uses the beta distribution to estimate PRL. We examine this new beta based model and four existing models for bias using simulated test data sets. Producing confidence intervals for PRL, we also analyse the relationship between sample size and estimation error for each model and finally we consider the effect of extreme values on estimation procedures. We demonstrate that, under the assumption of lognormally distributed data with outliers, a two stage approach to testing which first detects and removes outliers from the data and then applies the beta based method is most satisfactory from both a theoretical and empirical perspective.
TL;DR: The Khewera Mines located in Pakistan contain the world's second largest reserves of rock salt, and the concentrations of naturally occurring radionuclides in rock salt were investigated to find that the mean annual effective dose for adults was lower than the average annually effective dose worldwide.
Abstract: The Khewera Mines located in Pakistan contain the world's second largest reserves of rock salt. Rock salt is used in Pakistan in food recipes. It was decided to investigate the concentrations of naturally occurring radionuclides in rock salt from the Khewera Mines. Samples of rock salt were collected from 10 different locations and analysed by gamma spectrometry. The mean activity concentrations of 226Ra, 232Th and 40K were 790 +/- 262, 640 +/- 162 and 23 000 +/- 6000 mBq kg(-1), respectively. The mean annual effective dose due to the intake of natural radionuclides from rock salt for adults was estimated to be 0.0638 +/- 0.015 mSv, which is lower than the average annual effective dose of 0.29 mSv received per caput worldwide due to the ingestion of natural radionuclides, as reported by the United Nations Scientific Committee on the Effects of Atomic Radiation in 2000.
TL;DR: Specific activities of 226Ra, 232Th and 40K were measured in brick, sand, marble and cement samples collected from different localities of the North West Frontier province and federally administered tribal areas, Pakistan, using a P-type coaxial high-purity germanium spectrometer.
Abstract: Brick, sand, marble and cement are mainly used for the construction of dwellings in Pakistan. Therefore, knowledge of the presence of natural radioactivity in these materials is of great importance in order to assess the radiological hazards associated with them. In this context, specific activities of 226Ra, 232Th and 40K were measured in brick, sand, marble and cement samples collected from different localities of the North West Frontier province and federally administered tribal areas, Pakistan, using a P-type coaxial high-purity germanium spectrometer. In brick samples, the average measured activities for 226Ra, 232Th and 40K were 30 ? 15, 41 ? 21 and 523 ? 182?Bq?kg?1, whereas in sand samples, these values were 19 ? 9, 30 ? 15 and 769 ? 461?Bq?kg?1, respectively. In marble samples, the average specific activities of 226Ra, 232Th and 40K were found to be 18 ? 19, 18 ? 21 and 299 ? 328?Bq?kg?1, whilst in cement samples they were 24 ? 6, 18 ? 4 and 244 ? 29?Bq?kg?1, respectively. Radium equivalent activities were also calculated and were found to be 129 ? 54, 121 ? 57, 67 ? 60 and 68 ? 9?Bq?kg?1 for brick, sand, marble and cement samples, respectively. The annual average effective doses from these samples were 0.37 ? 0.15, 0.33 ? 0.15, 0.20 ? 0.17 and 0.20 ? 0.03?mSv, respectively. External and internal hazard indices were less than one for all the samples studied.
TL;DR: Two epidemiological studies of cancer and proximity to high-voltage power lines are performed in the UK and the methods used to calculate exposure to magnetic fields in these studies are described, including the steps taken to ensure their trustworthiness.
Abstract: Two epidemiological studies of cancer (one for children and one for adults) and proximity to high-voltage power lines are being performed in the UK. We describe the methods used to calculate exposure to magnetic fields in these studies. We used grid references derived from addresses for subjects and compared these to the grid references of pylons to calculate distances to power lines. We gathered relevant data on the power lines and used these to calculate magnetic fields. This required information on loads in the years from 1962 to the present. The only such information now available is a prediction of loads made for each year in advance, and the use of predictions rather than actual loads is the biggest source of error in these calculations. For a recent year, we compare the loads used in these studies with actual loads to assess the accuracy of our calculations. These calculations were performed by industry, and we describe the steps taken to ensure their trustworthiness, including conducting them all blind to the case-control status of the subjects.
TL;DR: Detailed data have been reported for Pakistan on monitoring of the radiological health hazards of naturally occurring radionuclides using a high purity germanium detector or a sodium iodide detector.
Abstract: Humans have always been exposed throughout their period of existence to naturally occurring ionising radiation. Specifically, naturally occurring radionuclides are present in variable amounts in our environment. To assess radiological health hazards, naturally occurring radionuclides are being measured in soil, sand, marble, bricks etc throughout the world. In this regard, extensive data have been reported for Pakistan, which have been compiled and reviewed in this article. The majority of the reported articles are about monitoring of the radiological health hazards of naturally occurring radionuclides. In a few articles, use of the radionuclides has been reported for the exploration of uranium and thorium deposits. Most of the reported data have been obtained using a high purity germanium detector or a sodium iodide detector.
TL;DR: Regulatory activities which have been carried out to support the supervision of radiological protection during recovery of waste and spent fuel, and to support regulatory decisions on overall site remediation are described.
Abstract: In the 1960s two technical bases for the Northern Fleet were created in the Russian northwest at Andreeva Bay in the Kola Peninsula and Gremikha village on the coast of the Barents Sea. They maintained nuclear submarines, receiving and storing radioactive waste and spent nuclear fuel. No further waste was received after 1985, and the technical bases have since been re-categorised as temporary storage sites. The handling of these materials to put them into a safe condition is especially hazardous because of their degraded state. This paper describes regulatory activities which have been carried out to support the supervision of radiological protection during recovery of waste and spent fuel, and to support regulatory decisions on overall site remediation. The work described includes: an assessment of the radiation situation on-site; the development of necessary additional regulatory rules and standards for radiation protection assurance for workers and the public during remediation; and the completion of an initial threat assessment to identify regulatory priorities. Detailed consideration of measures for the control of radiation exposure of workers and radiation exposure of the public during and after operations and emergency preparedness and response are complete and provided in sister papers. The continuing requirements for regulatory activities relevant to the development and implementation of on-going and future remediation activities are also outlined. The Norwegian Radiation Protection Authority supports the work, as part of the Norwegian Government's plan of action to promote improvements in radiation protection and nuclear safety in northwest Russia.
TL;DR: It seems unlikely that the elemental concentrations in the food products analysed will contribute significantly to public health risks in the country, as the cumulative ingestion effective dose values from (226)Ra and (228)Th were found to be low.
Abstract: Samples of some domestic and imported food products of nutritive importance to both the child population and the adult population in Nigeria were collected and analysed in order to determine their radionuclide contents. The samples were collected from open markets in major commercial cities in the country. Gamma-ray spectrometry was employed in the determination of the radionuclide contents in the products. The gamma-ray peaks observed with reliable regularity in all the samples analysed belong to naturally occurring radionuclides, namely 226Ra, 228Th and 40K. The activity concentrations of these radionuclides in both the domestic and imported products were observed to be not significantly different. Essentially radioactive elements such as 137Cs were not detected in any of the samples. The non-detection of 137Cs in the imported products may be attributed to the suitably modified agricultural practices and countermeasures being employed to reduce caesium uptake by plants after the Chernobyl nuclear reactor accident. It seems unlikely that the elemental concentrations in the food products analysed will contribute significantly to public health risks in the country, as the cumulative ingestion effective dose values from 226Ra and 228Th were found to be low. Although 40K has the highest activity concentrations in all the samples analysed, it is usually under homeostatic control in the body, and hence the concentrations are irrelevant to possible contamination in the food products analysed.
TL;DR: A system of recommended dose constraints and derived control levels formulated for each option for STS remediation and new industrial facilities and buildings on the remedied sites had, until now, no analogues in the Russian system of regulation of radiation-hygienic standardisation.
Abstract: In the 1960s, two technical bases of the Northern Fleet were created in Northwest Russia, at Andreeva Bay in the Kola Peninsula and Gremikha village on the coast of the Barents Sea. They maintained nuclear submarines, performing receipt and storage of radioactive waste and spent nuclear fuel, and are now designated sites of temporary storage (STSs). An analysis of the radiation situation at these sites demonstrates that substantial long-term remediation work will be required after the removal of the waste and spent nuclear fuel. Regulatory guidance is under development to support this work. Having in mind modern approaches to guaranteeing radiation safety, the primary regulatory focus is on a justification of dose constraints for determining acceptable residual contamination which might lead to exposure to workers and the public. For these sites, four principal options for remediation have been considered—renovation, conversion, conservation and liquidation. This paper describes a system of recommended dose constraints and derived control levels formulated for each option. The unconditional guarantee of long-term radioecological protection provides the basis for criteria development. Non-exceedance of these dose constraints and control levels implies compliance with radiological protection objectives related to the residual contamination. Dose reduction below proposed dose constraint values must also be carried out according to the optimisation principle. The developed criteria relate to the condition of the facilities and the STS areas after the termination of remediation activities. The proposed criteria for renovation, conversion, conservation and liquidation are entirely within the dose limits adopted in Russia for the management of man-made radiation sources, and are consistent with ICRP recommendations and national practice in other countries. The proposed criteria for STS remediation and new industrial (non-radiation-hazardous) facilities and buildings on the remedied sites had, until now, no analogues in the Russian system of regulation of radiation-hygienic standardisation. The proposals made here may serve as a basis for corresponding standards at other sites.
TL;DR: The variety of techniques observed revealed the need for a nationwide survey concerning screening mammography in Greece, and large differences were observed among the different mammography facilities, mainly in terms of the tube potential setting and the MLO angle used.
Abstract: The objectives of this study were to investigate the techniques currently used for screening mammography in Greece, to estimate the mean glandular dose (MGD) for establishing a baseline radiation dose database, to analyse the effects of various factors on MGD, and to compare the results with others in the literature. Five mammographic facilities and 250 women having as a routine screening mammogram one craniocaudal (CC) and one mediolateral oblique (MLO) projection in each breast were included in the study. The parameters recorded were age, weight, compressed breast thickness (CBT), tube potential (kV), tube loading (mA s) and MLO projection angle. Large differences were observed among the different mammography facilities, mainly in terms of the tube potential setting and the MLO angle used. The average MGD per exposure was 1.4 ± 0.6 mGy while the respective averages separately for the CC and MLO projections were 1.2 ± 0.5 and 1.5 ± 0.7 mGy, respectively. The average MGD values recorded in this study were below the limit of 2 mGy established for the reference medium-sized breast of 4.5 cm CBT. However, the variety of techniques observed revealed the need for a nationwide survey concerning screening mammography in Greece.
TL;DR: It has been reported that thoron levels in China are above the world average and may therefore make a significant contribution to the natural background radiation dose and a pilot study of concentrations of both thoron and radon progeny during the spring of 2006 in the Beijing area, China was conducted.
Abstract: It has been reported that thoron levels in China are above the world average and may therefore make a significant contribution to the natural background radiation dose. We therefore conducted a pilot study of concentrations of both thoron and radon progeny during the spring of 2006 in the Beijing area, China. A new type of portable 24 h integrating monitor with a CR-39 detector was used during the survey. Seventy dwellings and eight outdoor sites were measured during the survey. For country houses built of red bricks and slurry, the average equilibrium equivalent concentrations (EEC) of thoron and radon were 1.02 +/- 0.48 and 16.41 +/- 9.02 Bq m(-3), respectively, whereas for city dwellings built of cement blocks and floor slabs, the results were 0.48 +/- 0.47 and 11.50 +/- 6.99 Bq m(-3) for thoron and radon, respectively. For outdoor air, concentrations of thoron and radon progeny were 0.29 +/- 0.28 and 7.05 +/- 2.68 Bq m(-3), respectively. Radiation exposures from thoron and radon progeny were also evaluated; the ratio of dose contribution from thoron progeny to that of radon progeny was evaluated to be 28% and 17% in country houses and city dwellings, respectively.
TL;DR: The activity concentrations of (226)Ra, (232)Th and (40)K in seven brands of Portland cement used in Nigeria have been determined using a gamma-ray spectrometer with a hyperpure germanium detector, and were within the recommended limits for safety.
Abstract: The activity concentrations of 226Ra, 232Th and 40K in seven brands of Portland cement used in Nigeria have been determined using a gamma-ray spectrometer with a hyperpure germanium detector. A total of 22 samples were collected from suppliers. The mean activity concentrations varied between 19.2 and 85.1?Bq?kg?1, 12.9 and 31.7?Bq?kg?1, and 31.5 and 116?Bq?kg?1 for 226Ra, 232Th and 40K, respectively, which are lower than the world averages for building materials. The average values of 226Ra, 232Th and 40K content of all the cement samples are 43.8, 21.5 and 71.7?Bq?kg?1, respectively. The results of the radium equivalent activity, external hazard index, gamma activity index and alpha index calculated were all within the recommended limits for safety, and compare well with results obtained in some other countries of the world.
TL;DR: A positive correlation has been observed between uranium content and radon exhalation rate and the average value of annual effective dose for cave workers is 1.98 mSv y(-1), while for visitors it is 2.4 microSv per visit.
Abstract: Activity concentrations of 238U, 232Th and 40K in rocks and soil samples collected from Sannur cave, Beni Suef governorate, eastern desert of Egypt, were determined using the high-resolution gamma spectrometry technique. The results show that the concentrations of the naturally occurring radionuclides are the following: 238U ranged from 8.51 ± 1.23 to 20.66 ± 2.12 Bq kg−1, 232Th ranged from 7.69 ± 1.02 to 22.73 ± 1.60 Bq kg−1 and 40K ranged from 185.74 ± 0.42 to 2084.70 ± 23.30 Bq kg−1. The radium equivalent activity (Raeq), the absorbed dose rate (D), and the external hazard index (Hex) were also calculated and compared to the international recommended values. The radon concentration and radon exhalation rate from the rock and soil samples were measured using the Can technique. The average value of annual effective dose for cave workers is 1.98 mSv y−1, while for visitors it is 2.4 µSv per visit. The radon exhalation rate varies from 0.21 ± 0.03 to 1.28 ± 0.02 Bq m−2 h−1. A positive correlation has been observed between uranium content and radon exhalation rate.
TL;DR: This work deals with the measurement of radioactivity and radon exhalation rate from building materials manufactured in Douala city from geological materials, and a correlation (correlation coefficient approximately 0.8) was found between radium concentration measured with a HPGe detector and the radonExhalation Rate obtained using nuclear track detectors.
Abstract: This work deals with the measurement of radioactivity and radon exhalation rate from building materials manufactured in Douala city from geological materials. Nine types of building material were surveyed for their natural radioactivity contents using high-resolution gamma-ray spectrometry. The activity concentrations for 226Ra, 232Th and 40K varied from 11.5 to 49 Bq kg−1, 16 to 37 Bq kg−1 and 306 to 774 Bq kg−1, respectively. The absorbed dose rate in the samples investigated at 1 m above ground level ranged from 28.5 to 66.6 nGy h−1. External and internal hazard indices were also estimated as defined by the European Commission. The Ra equivalents of the materials studied ranged from 57.5 to 133 Bq kg−1 and are much smaller than the recommended limit of 370 Bq kg−1 for construction materials for dwellings. Polycarbonate nuclear track detectors (NTDs), type CR-39, were used for measuring the radon concentration from different materials. In fact, knowledge of the radon exhalation rate from building materials is important for understanding the individual contribution of each material to the total indoor radon exposure. Samples were hermetically closed in glass vessels and the radon growth was followed as a function of time. The radon exhalation rate was therefore derived from the experimental measurement of α-track densities. The radon exhalation varied from (5.77 ± 0.06) × 10−5 to (7.61 ± 0.07) × 10−5 Bq cm−2 h−1 in bricks, from (5.79 ± 0.05) × 10−5 to (11.6 ± 0.12) × 10−5 in tiles, and was (6.95 ± 0.03) × 10−5 Bq cm−2 h−1 in concrete. A correlation (correlation coefficient ) was found between radium concentration measured with a HPGe detector and the radon exhalation rate obtained using nuclear track detectors.
TL;DR: Values of both transfer coefficients and discrimination factor for transfer from soil via the diet to both critical organs and the whole body have been calculated for important elements in radiation protection, including alkaline earths, alkali metals, rare earths and other related elements.
Abstract: Based on results from recent studies of elemental dietary intake and organ or tissue content for adult Chinese men, quoted nationwide elemental concentrations in Chinese soil and newly published national average consumption of dietary foods, values of both transfer coefficients and discrimination factor (DF) for transfer from soil via the diet to both critical organs and the whole body have been calculated for important elements in radiation protection, including alkaline earths, alkali metals, rare earths and other related elements. These calculations have used both the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) model and the DF method. In the UNSCEAR model, the basic parameters used to describe the transport of radionuclides are the transfer coefficients Pij, which describe the relationship of concentrations or other amounts between compartment i and the following compartment j, whereas the DF is the ratio between the transfer coefficients for one element and a chemically similar element. From a comparison of the transfer coefficients of different elements for a particular transport pathway, those for alkaline earths are generally speaking higher than those for halogen elements and alkali metals, whereas those for rare earth elements, U and Th are lower. Relative to Ca, the DFs of transfer from soil to diet and from diet to critical organs or the whole body for the other alkaline earth elements and Pb are all less than 1, the DFs for the other elements decrease with increasing or decreasing atomic number. For alkali metals, the DFs of transfer from diet to critical organs and the whole body seem to increase with increasing atomic number, but those from soil to diet decrease with increasing atomic number.
TL;DR: The effective doses received by the residents of different types of house within all Egyptian governorates were assessed using the WinMat computer program and the results were below 1 mSv a(-1) in all cases.
Abstract: Natural radioactivity due to the presence of 226Ra, 232Th and 40K in selected building materials (cement, sand, bricks, gypsum and ceramic) used in Egypt was measured using a gamma-ray spectrometer with an HPGe detector. The average activity concentrations observed in different building materials ranged from 10.0 ? 1.3 to 109 ? 6, <2 to 55.8 ? 2.2 and 5.5 ? 1.7 to 684 ? 34?Bq?kg?1 for 226Ra, 232Th and 40K, respectively. Based on these, together with previously reported results, the effective doses received by the residents of different types of house within all Egyptian governorates were assessed using the WinMat computer program. The results were below 1?mSv?a?1 in all cases. The collective effective dose indoors was assessed as 15?000?man?Sv and the excess effective dose due to building materials was 0.07?mSv?a?1.
TL;DR: Calculated scatteredAir kerma and the minimum required lead shielding were found to be frequently overestimated compared to the measured air kerma, on average almost five times the measured scattered air Kerma.
Abstract: Currently in the UK, shielding calculations for computed tomography (CT) systems are based on the BIR-IPEM (British Institute of Radiology and Institute of Physics in Engineering in Medicine) working group publication from 2000. Concerns have been raised internationally regarding the accuracy of the dose plots on which this method depends and the effect that new scanner technologies may have. Additionally, more recent shielding methods have been proposed by the NCRP (National Council on Radiation Protection) from the USA. Thermoluminescent detectors (TLDs) were placed in three CT scanner rooms at different positions for several weeks before being processed. Patient workload and dose data (DLP: the dose length product and mAs: the tube current-time product) were collected for this period. Individual dose data were available for more than 95% of patients scanned and the remainder were estimated. The patient workload data were used to calculate expected scatter radiation for each TLD location by both the NCRP and BIR-IPEM methods. The results were then compared to the measured scattered radiation. Calculated scattered air kerma and the minimum required lead shielding were found to be frequently overestimated compared to the measured air kerma, on average almost five times the measured scattered air kerma.
TL;DR: In this paper, all the studies concerning radon measurements have been reviewed and the main emphasis is on different methods used in the measurement of radon A minimum value of 5 Bqm−m−3 has been reported for a centrally air conditioned room and a maximum value of 782 ± 125 Bq m−3 was observed in coal mines of Khushab, Punjab.
Abstract: Radon is being extensively measured all over the world due to its hazardous health effects as well as for different geological applications In this regard, considerable studies have been conducted by different research groups in Pakistan However, these studies are scattered and need to be combined/listed somewhere for future studies of radon in Pakistan In this article, all the studies concerning radon measurements have been reviewed The main emphasis is on different methods used in the measurement of radon A minimum value of 5 Bq m−3 has been reported for a centrally air conditioned room and a maximum value of 782 ± 125 Bq m−3 has been observed in coal mines of Khushab, Punjab