| 1. |
- Magnusson, Åsa, et al.
(författare)
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Levels of C-14 in the terrestrial environment in the vicinity of two European nuclear power plants
- 2004
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Ingår i: Radiocarbon. - 0033-8222. ; 46:2, s. 863-868
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Tidskriftsartikel (refereegranskat)abstract
- Radiocarbon is produced in all types of nuclear reactors. Most of the C-14 released into the environment is in the form of gaseous emissions. Recent data on the C-14 concentration found in terrestrial samples taken in the vicinity of nuclear power plants in Romania and Lithuania are presented. We found increased C-14 levels in the surroundings of both power plants. At the Romanian power plant Cernavoda, we found excess levels of C-14 in grass within a distance of about 1000 in, the highest C-14 specific activity being 311 Bq/kg C (approximately 28% above the contemporary C-14 background) found at a distance of 200 in from the point of release (nearest sampling location). At the Lithuanian power plant Ignalina, samples of willow, pine, and spruce showed a C-14 excess of similar magnitude, while significantly higher values were found in moss samples. The samples were analyzed at the accelerator mass spectrometry facility in Lund, Sweden.
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| 2. |
- Rääf, Christopher, et al.
(författare)
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Body burden and excretion of 137-Cs and 40K in subjects from the south of Sweden
- 2000
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Ingår i: Journal of Environmental Radioactivity. - 1879-1700. ; 47:1, s. 83-100
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Tidskriftsartikel (refereegranskat)abstract
- The equivalent biological half-times, Te, of 137Cs and 40K in a South-Swedish urban population have been determined through whole-body measurements and urinary excretion analysis. The Te - values for 137Cs found in males were on average, significantly lower than what is given in the literature. The relatively low average whole-body content of 40K,QK, in the males could explain the discrepancy, taking into consideration that a positive correlation between the Te and QK has been suggested in an earlier work. Furthermore, the potassium-normalized caesium urinary excretion was determined for the subjects in the study, and values were found to be in accordance with earlier results. A literature study of previous experimental data on the potassium-normalized caesium excretion however raises some questions about its applicability as a method for estimating the whole-body burden of 137Cs through urine analysis.
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| 3. |
- Rääf, Christopher, et al.
(författare)
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Calculation models for the transfer of radioactive substances from a deep repository for spent nuclear fuel to the biosphere
- 2001
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Ingår i: Kunskapsläget på kärnavfallsområdet 2001: rapport. - 0375-250X. - 9138214466 ; :35, s. 257-318
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter summarizes the state of knowledge about models which describe how radioactive substances from a geological repository can be transferred through ecosystems to flora, fauna and mankind. Radionuclide migration to the biosphere and to man primarily occurs via groundwater flows passing through the repository. For such migration to occur, the integrity of the repository barrier system must be breached, for example, due to manufacturing defects in the copper canisters containing the spent nuclear fuel or as a result of long-term corrosion in the canister or due to other canister defects. The groundwater is connected to various water systems such as wells, marshes and wetlands, lakes, water courses as well as coastal and sea waters. The groundwater can also contaminate cultivated land via groundwater transport to the cultivation zone and via irrigation. The dilution volumes in the various water systems of the biosphere largely determine the consequences from leakage from a deep repository for spent nuclear fuel in the form of radiation doses to man and animals. Another exposure pathway from a deep repository to man is via bottom sediment in seas and lakes which, after future land rise, may dry up and later be cultivated to produce foodstuffs.
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| 4. |
- Rääf, Christopher, et al.
(författare)
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Ecological half-time of radiocesium from Chernobyl debris and from nuclear weapons fallout as measured in a group of subjects from the south of Sweden
- 2001
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Ingår i: Health Physics. - 1538-5159. ; 81:4, s. 366-377
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Tidskriftsartikel (refereegranskat)abstract
- From 1960 to 1980 and between 1987 and 1994 the whole-body content of 17Cs, and when possible also 134Cs, was measured in a group of subjects living in the city of Lund, Sweden (55.7 degrees N, 13.2 degrees E). The results have been analyzed to estimate the effective ecological half-time of fallout radiocesium in humans living in the area. The Lund area (The Province of Skane) was subjected to a deposition of about 2 kBq m(-2) of pre-Chernobyl 137Cs from nuclear weapons testing and 1 kBq m(-2) of 137Cs from Chernobyl fallout in May 1986. The radiocesium from the nuclear weapons tests in the 1950's and 1960's still gave a significant contribution to the total 137Cs levels in humans in the post-Chernobyl study period (1987-1994) of about 0.4 Bq per kg body weight, which was about 10% of the peak post-Chernobyl concentration level of 137Cs (3.5-4 Bq kg(-1)) in 1987. The effective ecological half-time for 137Cs from Chernobyl was found to be 1.8 +/- 0.2 y. The aggregate transfer factor from deposition to mean activity concentration in man was estimated to be 3.6 Bq kg(-1)/kBq m(-2). These values may be compared with an effective ecological half-time of 1.3 y found in the reference group in the 1960's, and an aggregate transfer factor of 10 Bq kg(-1)/kBq m(-2). This difference is largely explained by the continuous nature of the global fallout leading to contamination on growing crops whereas the Chernobyl fallout occurred just prior to the South Swedish growing season, leading to less efficient transfer to crops and to human diet. The average committed individual effective dose (50 y) from ingested 137Cs from the Chernobyl fallout was estimated to be 0.02 mSv and from the nuclear weapons fallout (1945-1995) to be 0.20 mSv.
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| 5. |
- Rääf, Christopher
(författare)
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Human Metabolism and Ecological Transfer of Radioactive Caesium
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The whole-body content of radiocaesium was measured in a South-Swedish urban group of people residing in the city of Lund (55.7°N, 13.2°E) between 1960 and 1994. The results from the survey have been analysed in order to estimate the ecological half-time, Teco,eff, of fallout radiocaesium and the aggregate transfer from ground deposition to man in the region. After 1987, the biological half-times, Te, of 137Cs and 40K in man were also determined in the reference group through whole-body content measurements in combination with 24-hour urine sampling. Relationships between 24-hour urinary excretion and body burden of 137Cs in the group together with data from the literature were then applied to urine samples collected in 1994 and 1995 from adult subjects living in the highly contaminated region of Bryansk, Russia, in order to estimate their average body burden of 137Cs. The equivalent biological half-time for 137Cs in females of the Lund reference group was, on average (±1 WSE), 66±3 d, which agrees with other findings, whereas the value for the males, 81±4 d, was, on average, significantly lower than what is found in the literature. This is partly explained by the elevated mean age and relatively low mean body muscle mass of the males investigated in the group during the post-Chernobyl study period. The effective ecological half-time for 137Cs from Chernobyl was found to be 1.8± 0.2 y. The aggregate transfer of 137Cs from deposition to mean activity concentration in man was estimated to be 1.7 Bq kg-1/kBq m-2. These values may be compared with an effective ecological half-time of 1.3 years found in the reference group in the 1960s, and an aggregate transfer factor of 9.8 Bq kg-1/kBq m-2. The average committed effective dose from ingested 137Cs Chernobyl fallout in the study group was estimated to be 0.02 mSv and from the nuclear weapons fallout to 0.20 mSv. The estimates of whole-body content of 137Cs in the Russian subjects obtained through creatinine normalisation of the 137Cs content in urine were, on average, a factor of 2 higher than estimates obtained through a potassium normalisation procedure; 55±8 (1 SE) kBq for creatinine and 29±4 (1 SE) kBq for potassium normalisation in the year 1994. This was due to a significant difference in the relationship between the urinary potassium and creatinine concentration between the Swedish and Russian group. The elevated potassium concentration found in the rural Russian subjects indicated a higher dietary intake of potassium, which greatly influences the accuracy and applicability of the potassium normalisation method when estimating body burden of 137Cs through urine assay. It is therefore recommended not to use the potassium normalisation procedure in cases where the daily intake of potassium is unknown. The estimated body burden of 137Cs in the Bryansk group in 1994 corresponds to a contribution to the estimated annual effective dose of 1.8 mSv y-1, which is approximately 200 times greater than the average annual dose received from ingested 137Cs by the subjects of the Lund reference group during the period 1987-1994.
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| 6. |
- Rääf, Christopher, et al.
(författare)
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Human metabolism of radiocaesium revisited
- 2004
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 112:3, s. 395-404
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Tidskriftsartikel (refereegranskat)abstract
- Three adult volunteers (2 males and I female) have ingested radioactive caesium in two edible forms in order to compare the gastrointestinal uptake and the subsequent short-term and long-term biokinetics. Foodstuffs made of fresh-water fish or mushrooms from regions in Sweden of high Cs-137 deposition was ingested together with a (CsCl)-Cs-134-solution mixed with soft drinks. Whole-body countings of Cs-134 and Cs-137 were performed in the Malmo whole-body counter during a period of similar to50 d prior to, and 200-300 d after the ingestion. Urine and faeces were collected the day before and up to 7-10 d after the test meals, and analysed for Cs-134 and Cs-137. No significant difference in the gastrointestinal uptake fraction, f(0) = 0.98 between caesium incorporated into a foodstuff matrix and caesium in ionic form was detected. Cumulated faecal excretion during 7 d after ingestion accounted for 2-3% of the intake. No significant difference in the long-term biological half-time was found between caesium present in a food matrix and in an aqueous solution in any of the volunteers.
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| 7. |
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