| 1. |
- Almgren, Sara, 1979, et al.
(författare)
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Gamma radiation doses to people living in Western Sweden.
- 2008
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Ingår i: Journal of environmental radioactivity. - : Elsevier BV. - 0265-931X. ; 99:2, s. 394-403
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Tidskriftsartikel (refereegranskat)abstract
- Indoor environments contribute to gamma radiation in the general population. The aims of the present study were to investigate average gamma radiation doses in a rural and an urban area of Sweden, compare indoor dose rates with personal exposure, and study the effects of building characteristics on radiation levels. Radiation was measured with thermoluminescence dosimeters (TLDs). Repeated measurements were performed with TLDs worn by participants (n=46) and placed in their dwellings. Personal dose rates were 0.092microSv/h (rural) and 0.096microSv/h (urban). The mean effective gamma dose rates in dwellings were 0.091microSv/h (rural) and 0.11microSv/h (urban), which are higher than the world average. Dose rates in apartments were higher than in detached houses and higher for concrete than wooden dwellings. Personal dose rates were strongly associated with dwelling dose rates (r(p)=0.68, p<0.01) and could be modelled. Within-participant variability was low.
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| 2. |
- Almgren, Sara, 1979, et al.
(författare)
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GIS supported calculations of (137)Cs deposition in Sweden based on precipitation data.
- 2006
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Ingår i: The Science of the total environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 368:2-3, s. 804-13
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Tidskriftsartikel (refereegranskat)abstract
- It is of interest to know the spatial variation and the amount of (137)Cs e.g. in case of an accident with a radioactive discharge. In this study, the spatial distribution of the quarterly (137)Cs deposition over Sweden due to nuclear weapons fallout (NWF) during the period 1962-1966 was determined by relating the measured deposition density at a reference site to the amount of precipitation. Measured quarterly values of (137)Cs deposition density per unit precipitation at three reference sites and quarterly precipitation at 62 weather stations distributed over Sweden were used in the calculations. The reference sites were assumed to represent areas with different quarterly mean precipitation. The extent of these areas was determined from the distribution of the mean measured precipitation between 1961 and 1990 and varied according to seasonal variations in the mean precipitation pattern. Deposition maps were created by interpolation within a geographical information system (GIS). Both integrated (total) and cumulative (decay corrected) deposition densities were calculated. The lowest levels of NWF (137)Cs deposition density were noted in north-eastern and eastern parts of Sweden and the highest levels in the western parts of Sweden. Furthermore the deposition density of (137)Cs, resulting from the Chernobyl accident was determined for an area in western Sweden based on precipitation data. The highest levels of Chernobyl (137)Cs in western Sweden were found in the western parts of the area along the coast and the lowest in the east. The sum of the deposition densities from NWF and Chernobyl in western Sweden was then compared to the total activity measured in soil samples at 27 locations. Comparisons between the predicted values of this study show a good agreement with measured values and other studies.
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| 3. |
- Almgren, Sara, 1979, et al.
(författare)
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Long-term investigation of anthropogenic and naturally occurring radionuclides at reference sites in western Sweden.
- 2009
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Ingår i: Journal of environmental radioactivity. - : Elsevier BV. - 1879-1700 .- 0265-931X. ; 100:7, s. 599-604
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Tidskriftsartikel (refereegranskat)abstract
- In case of an accidental release of radioactive substances into the environment, it is important to quickly and reliably estimate the radiation dose received by people in the affected area, and to determine the extent of the contamination. Measurements of the extent of the release and the subsequent contamination can be facilitated if there are predetermined reference sampling sites with known background radiation and inventory of radionuclides. Since 1996, 34 reference sites for soil sampling, field gamma, and intensimeter measurements have been established in western Sweden. Time series data for dose rates and radioisotope inventory have been collected at these sites, allowing for the investigation of changes in these parameters over time. The mass activity densities for the uranium and thorium series elements varied approximately between 10 and 50 Bq/kg and between 10 and 40 Bq/kg, respectively. The mass activity density of (40)K was approximately in the range 300-800 Bq/kg. The radiation exposure due to (137)Cs was rather small in this area. The dose rates calculated from in situ measurement data showed that the contribution to the total dose rate was almost entirely due to naturally occurring radionuclides. The measured dose rate was about twice as high as the calculated rate, even after subtracting the contribution from cosmic radiation. This may be explained by the fact that intensimeters generally are calibrated to measure the quantity ambient dose equivalent, which should not underestimate the effective dose.
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| 4. |
- Almgren, Sara, 1979, et al.
(författare)
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Measurements and comparisons of gamma radiation doses in a high and a low (137)Cs deposition area in Sweden.
- 2008
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Ingår i: Journal of environmental radioactivity. - : Elsevier BV. - 0265-931X. ; 99:11, s. 1750-5
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Tidskriftsartikel (refereegranskat)abstract
- Sweden is one of the countries affected by the Chernobyl fallout. The aim of the present study was to investigate the average radiation dose to people living in a high-deposition area (the parish of Hille) in Sweden for comparison with dose rates previously measured in a low-deposition area in western Sweden. Individual measurements (personal and dwelling dose rates) were performed using thermoluminescence dosimeters in 24 randomly chosen individuals. Dwelling and personal dose rates in Hille were 0.12 and 0.11 microSv/h, respectively. The dose rates in Hille were slightly higher than in western Sweden (difference for detached houses=0.024 microSv/h for personal and 0.030 microSv/h for dwelling dose rates), partly because of the higher (137)Cs deposition. In wooden houses, the difference was somewhat greater. Our results indicate a current contribution to personal gamma radiation in this area of about 0.2 mSv per year from the Chernobyl fallout.
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| 5. |
- Almgren, Sara, 1979
(författare)
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Studies on the Gamma Radiation Environment in Sweden with Special Reference to 137Cs
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gamma radiation in the environment today mainly originates from naturally occurring radionuclides, but anthropogenic radionuclides, such as 137Cs, contribute in some areas. In order to assess population exposure in case of fallout from nuclear weapons (NWF) or accidents, knowledge and monitoring of external gamma radiation and radionuclide concentrations in the environment is important. For this purpose 34 sampling sites were established in western Sweden and repeated soil sampling, field gamma spectrometry (in situ measurements), and dose rate measurements were performed. The variations in the activities between the different sampling occasions were found to be quite large. The naturally occurring radionuclides were the main source of outdoor dose rates. The uranium and thorium decay series contributed about equally to the total dose while the contribution from 40K was somewhat higher. The dose rates were mainly correlated to the ground cover, with higher levels on asphalt and cobble stones than on grass. The large scale deposition densities from NWF and the Chernobyl accident could be relatively well estimated by a model including the amount of precipitation and measured deposition at few reference sites. The deposition density from nuclear weapons tests in Sweden between 1962 and 1966 was found to be 1.42-2.70 kBq/m2 and the deposition density from Chernobyl in western Sweden ranged between 0.82-2.61 kBq/m2. The vertical migration of 137Cs was studied at the sampling sites in western Sweden and a solution to the convection–diffusion equation (CDE) was fitted to depth profiles. The vertical migration of 137Cs was found to be very slow and diffusive transport was dominant at most locations. The apparent convection velocity and diffusion coefficient were found to be 0–0.35 cm/year and 0.06–2.63 cm2/year, respectively. The average depth of the maximum activity was 5.4±2.2 cm. The fitted depth distributions for each location were used to correct in situ measurements and the results agreed relatively well with the 137Cs inventories in soil samples. A widespread deposition of radionuclides was caused by the Chernobyl accident and parts of Sweden were highly affected. Today, approximately 20 years since the latest deposition, 137Cs can still be measured in the environment and contributes to additional doses to people. However, today people generally spend much time in their dwellings, and therefore, the radiation environment indoors is more important for the personal exposure. Dwelling and personal dose rate measurements in western Sweden (means: 0.099±0.035 μSv/h and 0.094±0.017 μSv/h, respectively) showed that concrete dwellings yield higher dose rates than those of wood. Measurements in a region with a high 137Cs deposition (Hille in eastern Sweden) showed somewhat higher dose rates in wooden dwellings than in western Sweden (0.033 μSv/h and 0.025 μSv/h higher, respectively). The additional contribution from the Chernobyl 137Cs fallout in Hille was estimated to be about 0.2 mSv/year.
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