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1.
The Chernobyl nuclear power plant accident in April 1986 caused a widely spread plume of radionuclides containing, amongst other materials, plutonium isotopes. The regional deposition of these nuclides in Finland has been assessed, based on samples of lichen, peat, precipitation, surface soil and grass. Unlike the deposition of transuranium elements from the weapons tests in the 1950"s and the 1960"s, the deposition in Finland from the Chernobyl accident was very unevenly distributed. Even then, the Chernobyl-derived deposition of 239,240Pu in the most contaminated regions of Finland was only around 10% of the global fallout from weapons tests. The total amount of 239,240Pu deposited in Finland was 1.1011 Bq (»25 g), i.e., approximately half of a percent of the activity deposited in the 1950"s and the 1960"s. In addition to the alpha-emitting Pu isotopes, the Chernobyl plume also contained a significant amount of the beta-emitting 241Pu, which is the precursor of the long-lived alpha-emitter 241Am. The highest plutonium deposition values were found in a relatively narrow swath from the southwestern coast of Finland northeastwards across the country. This is related to the calculated route of the air parcel trajectory associated with the initial explosion of the Chernobyl reactor. The high deposition values found in the northeastern part of the plume route over Finland can be attributed to the simultaneous occurrence of precipitation. The relatively high plutonium deposition in the southwestern part of Finland occurred, however, without concurrent precipitation. This indicates that the plutonium was at least partly associated with relatively large particles having a substantial deposition velocity due to gravitational setting  相似文献   

2.
Activity concentrations of 237Np in peat and lichen samples in Finland were determined and contributions from nuclear weapons testing in 1950–1960s and the Chernobyl accident were estimated. 237Np was determined with ICP-MS using 235Np as a tracer. Activity concentrations of 237Np in peat samples varied between 1.98 ± 0.05 and 14.1 ± 0.3 mBq/m2. The contribution from the Chernobyl accident to the total 237Np deposition in peat was 0.1–13%, the Chernobyl-derived fraction of total 237Np in peat being much lower than the previously determined corresponding Chernobyl-derived fractions of 239+240Pu, 241Pu, 241Am and 244Cm.  相似文献   

3.
Alpha-spectrometric Pu determinations in aerosol samples collected after the Chernobyl accident in Austria show a238Pu/239 (240)Pu ratio in the range of 0.33–0.76 with a most reliable value of 0.47. From241Am measurements in old Pu preparations and air filter analyses also241Pu activities have been calculated. The ratio241Pu/239 (240)Pu during the main contamination period is 74.6±5.7, when maximum241Pu concentrations in air achieved 4.5–6.0 mBq/m3.  相似文献   

4.
Summary 241Pu concentrations were calculated indirectly in different compartments of the southern Baltic ecosystem by the activity measurements of241Am isotope from the increase of the<span lang=EN-GB style='font-size:12.0pt;font-family:Symbol;mso-bidi-font-family:Symbol; mso-ansi-language:EN-GB'>b-emitting241Pu at 16-18 years after the Chernobyl accident. Enhanced levels of241Pu were observed in all analyzed samples. Maximum values (0.408 and 0.367 mBq. g-1d.w.) of the estimated241Pu concentrations were found in sediments of Internal Puck Bay and Gdańsk Bay, respectively, and in the suspended matter from water of Gdańsk Bay (77.8 mBq.g-1d.w.). The highest241Pu/239+240Pu activity ratio was found in the suspended matter (1500) and water (140). The241Pu activity of the air dust was very high in April 1986, 3643±34.3 mBq.g-1d.w., and the241Pu/239+240Pu activity ratio was 56, but the highest241Pu/239+240Pu activity ratio of the air dust was measured in August. Then the241Pu concentration in air dust decreased quickly to values similar to those before the Chernobyl accident.<span style='font-size:12.0pt'>This study provides new data for the 241Pu concentrations in various compartments of the Baltic Sea ecosystem.  相似文献   

5.
The deposition of transuranium elements in Sweden following the Chernobyl accident was investigated through the analysis of carpets of lichen-and moss-samples and also air-filters and precipitation. The impact of transuranium elements was small compared to that of radiocesium. The deposition of239+240Pu was, as for other actinides, inhomogeneously distributed and ranged from 0.1% to 100% of the inventory in 1986 from nuclear detonation tests. The activity ratio of239+240Pu/137Cs was between 10–3 and 10–6 in comparison to 10–2 for nuclear test fallout. The activity ratios of241Pu,242Cm,238Pu,243+244Am and239+240Pu were about 86, 14, 0.47, 0.14, and 0.13 respectively, but large variations were observed. The results from Sweden were compared with those found in South Finland, Denmark and Southern Europe. The deposition over Scandinavia originated from the initial explosion at Chernobyl, which contained relatively higher amounts of actinide elements than the second emission, which occurred a few days later and was a result of actions taken to bring the fire under control.  相似文献   

6.
Activity concentrations of Pu radioisotopes and 241Am were determined in the organic and mineral layers of four soil sections collected in 1996, providing for the first time information on the levels of these radionuclides in soil samples from Romania. The investigated site was an alpine pasture located in the Charpathian Mountains, in an area found as one of the most affected in Romania after the Chernobyl accident. In the examined soil sections radioactive inventories were estimated to be 500 Bq/m2 for 241Pu, 115 Bq/m2 for 239+240Pu, 8 Bq/m2 for 238Pu and 50 Bq/m2 for 241Am. On the basis of activity ratios in the soil profile, the source of the radioactive release is discussed.  相似文献   

7.
In 1968 a U.S. B-52 bomber from USA with four nuclear weapons crashed on the sea ice near the Thule air base and contaminated the surroundings. Most of contamination was recovered during the cleanup program. However, some of the plutonium still remains in the bottom sediments of the area. In 1997 an international expedition with a comprehensive sampling program was performed. A lot of sediment samples were taken with a Finnish Gemini corer. Sediment samples from 5 sampling stations, 80 samples altogether, were pretreated in Ris, Denmark, and analysed for transuranic elements at STUK, Finland. The samples were analysed primarily for Pu, but gamma-spectrometric measurements of 241Am were also made. Generally, the Pu concentrations in the area studied were from 1 to 3 magnitudes higher than the fallout level in the Arctic sea area. None of the vertical profiles of Pu at the various stations showed a typical Pu peak originating from the accident in 1968, but the sediments were mixed down and contaminated to the depths studied (20 cm). The presence of large quantities of hot particles distorted the estimations of mean concentrations and inventories. Samples with plutonium from the accident show significant variations of nuclide ratios, 238Pu/239,240Pu, 241Pu/239,240Pu and 241Pu/241Am. This indicates that Pu at Thule may be from more than one source of different quality.  相似文献   

8.
Artificial radionuclides in deposition and airborne dust samples in 1986 were measured at Tsukuba and 11 stations in Japan. In May 1986, the Chernobyl radioactivity was observed in rain and air samples in Japan. The Chernobyl-derived Pu isotopes, which are characterized by higher238Pu/239,240Pu (85) and241Pu/238Pu (0.5) activity ratios than those of the nuclear test-derived Pu and90Sr, were detected in deposition and airborne dust samples in Japan, as well as volatile radionuclides such as131I and137Cs. However, the activities of Pu isotopes and90Sr observed in Japan were about two and three orders of magnitude lower than those expected from the activity ratios in the total release at Chernobyl, which means that the residence time of Pu in the air was shorter than that of137Cs. In order to understand the fractionation between the Chernobyl radionuclides we studied about individual wet and dry deposition. The results suggest that this cause is due to the difference of the particle size of radionuclide-bearing particles, which may be related to the release process of Chernobyl radionuclides.  相似文献   

9.
The simultaneous determination of multiple actinide isotopes in samples where total quantity is limited can sometimes present a unique challenge for radioanalytical chemists. In this study, re-determination of 238Pu, 239+240Pu, and 241Am for soils collected and analyzed approximately three decades ago was the goal, along with direct determination of 241Pu. The soils had been collected in the early 1970’s from a shallow land burial site for radioactive wastes called the Subsurface Disposal Area (SDA) at the Idaho National Lab (INL), analyzed for 238Pu, 239+240Pu, and 241Am, and any remaining soils after analysis had been archived and stored. We designed an approach to reanalyze the 238Pu, 239+240Pu, and 241Am and determine for the first time 241Pu using a combination of traditional and new radioanalytical methodologies. The methods used are described, along with estimates of the limits of detection for gamma-and alpha-spectrometry, and liquid scintillation counting. Comparison of our results to the earlier work documents the ingrowth of 241Am from 241Pu, and demonstrates that the total amount of 241Am activity in these soil samples is greater than would be expected due to ingrowth from 241Pu decay.  相似文献   

10.
In the frame of an International Atomic Energy Agency Technical Cooperation project, a radiological survey was performed in the Araks and Kura Rivers (Azerbaijan). Sediment samples, and where available, aquatic plants were collected along these two rivers and their inflow and tributary rivers. 137Cs, 238U, 234U, 239+240Pu, 238Pu, 90Sr and 241Am activity concentrations were measured. The radionuclide levels measured were relatively low, and in most cases below the detection limit, as compared with those from other areas of the world which have been directly affected by effluents from nuclear installations or influenced by the Chernobyl accident. The results indicated that the radionuclides are of natural origin or attributable to the atmospheric fallout from nuclear weapons tests or to the Chernobyl-derived deposition.  相似文献   

11.
The paper presents the results of our study on 238Pu, 239Pu, 240Pu, 241Am and 90Sr concentration in human bones carried out on a set of 88 individual samples of central Europe origin. Bone tissue samples were retrieved under surgery while introducing hip joint implants. The conducted surgeries tend to cover either southern or northeastern parts of Poland. While for the southern samples only global fallout was expected to be seen, a mixed global and Chernobyl fallout were to be reflected in the others. Alpha spectrometry was applied to obtain activity concentration for 238Pu, 239+240Pu, 241Am, while liquid scintillation spectrometry for 90Sr and mass spectrometry to receive 240Pu/239Pu mass ratio. Surprisingly enough, and to the contrary to our expectations we could not see any significant differences in either Pu activity or Pu mass ratio between the studied populations. In both populations Chernobyl fraction proved marginal. The results on 90Sr and 241Am confirm similarities between the two examined groups.  相似文献   

12.
A chemical separation procedure is described which allows the direct determination of low241Pu activities in environmental samples with a windowless gas-flow proportional counter. While current separation schemes based on anion exchange yield counting sources of sufficient purity for subsequent -spectrometry, for -counting of241Pu additional purification steps are required. A combination of anion exchange from 9 mol/l HCl, LaF3 precipitation and TTA extraction was found to be suitable even for the analysis of long-range Chernobyl fallout samples which contained interfering radionuclides with -activities at least 3 to 4 orders of magnitude higher than usually encountered. No difference is detectable between the results of the present, direct procedure and the results of the conventional indirect method based on the build-up of241Am. Average241Pu/239+240Pu ratios in air and deposition samples taken at Neuherberg near Munich were 70±6 with the present procedure and 66±9 from241Am build-up.  相似文献   

13.
Depth profiles of the long-lived radionuclides, 137Cs, 90Sr, Pu isotopes and 241Am were examined in undisturbed sandy, peaty and Podsol soils in the Chernobyl 30 km exclusion zone sampled around 10 years after the accident. Two Podsol soils, which have different radioactive deposition characteristics, have also been examined. Activity ratios of 239,240Pu/137Cs, 90Sr/137Cs, and 241Am/137Cs in the 0-1 cm layer of the two Podsol soils differed very much. Speciation of the radionuclides by sequential selective extraction was examined in the soils. Depth profiles of the soils have been analyzed according to the speciation results and soil characteristics.  相似文献   

14.
A radiochemical procedure is described for the simultaneous determination of238Pu,239+240Pu,241Pu,241Am,242Cm,244Cm,89Sr, and90Sr in vegetation samples. The method was applied for the determination of these, radionuclides in grass, collected near Munich after the fallout from the reactor accident at Chernobyl, USSR. The specific activities observed were (in Bq kg–1 dry weight):238Pu, 0.077;239+240Pu, 0.15;241Pu, 3.9;241Am, 0.031;242Cm, 3.0;244Cm, 0.008;89Sr, 2000;90Sr, 99.  相似文献   

15.
To clarify environmental effects of the Chemobyl radionuclides, long-lived Chernobyl radioactivity (239,240Pu,238Pu,241Pu and90Sr) in deposition samples in May 1986 was measured at 11 stations in Japan. Temporal variation of weekly deposition of90Sr differed from that of volatile radionuclides such as131I and137Cs, which may reflect the released process at Chernobyl. On the other hand, the geographical distributions of the monthly deposition of long-lived radionuclides were similar to those of volatile radionuclides, in which maximum deposits of90Sr and plutonium were observed in Akita, a northwestern Japan Sea coast site of Honshu Island. Higher241Pu deposition in most of the stations, as well as high238Pu/239,240Pu activity ratios were observed. The241Pu/238Pu activity ratios in deposition samples were nearly equal to that in the total release, which is clear evidence that Chernobyl-derived plutonium was transported to Japan in May 1986 together with volatile radionuclides although the contribution of Chernobyl Pu was about three orders of magnitude lower than137Cs.  相似文献   

16.
The origin and release date of environmental plutonium have been assessed by the measurement of plutonium and americium isotopic composition. The applicability and sensitivity of different plutonium isotope ratios, 240Pu/239Pu and 241Pu/239Pu measured by inductively coupled plasma sector field mass spectrometry and 238Pu/239Pu analysed by alpha spectrometry, have been evaluated for origin determination in several types of environmental samples. With use of mixing models the contribution of different sources (e.g. global fallout or Chernobyl) can be calculated. By the measurement of the 241Am/241Pu isotope ratio, the release date (i.e. formation of 241Pu by irradiation) can be estimated in environmental samples, which is an important parameter to distinguish recent plutonium release from previous (e.g. Chernobyl) emissions.  相似文献   

17.
Strontium-90, plutonium and americium activity concentrations in a few samples of forest soils, some species of mushrooms and fern leaves have been determined. These results are compared with cesium activity concentrations in the same materials obtained in a previous work. Radiochemical procedures are described. The origin of the contamination (Chernobyl accident or nuclear test explosion release) is discussed. The90Sr activity concentration ranges from 0.6 Bq/kg (mushroom samples) to 48.4 Bq/kg (fern leaves). For239+240Pu, it ranges from not detected above background (mushrooms, fern) to 10.8 Bq/kg (humus layer of forest soil). The maximum concentration of241Am is found to be 2.4 Bq/kg (humus sample) and for238Pu it is 0.85 Bq/kg (also in the humus sample).  相似文献   

18.
In the paper the results of 241Pu activity concentration determination in the biggest Polish rivers are presented. The analysis of more than 100 river water samples showed the Vistula and the Odra as well as three Pomeranian Rivers are important sources of 241Pu in the southern Baltic Sea. There were differences in 241Pu activities depending on season and sampling site and the plutonium contamination came mainly from the global atmospheric fallout as well as the Chernobyl accident, which is confirmed by plutonium activity ratios of 241Pu/239+240Pu and 238Pu/239+240Pu.  相似文献   

19.
The objectives of this study were to establish a ratio for241Am to239Pu in soil at the Rocky Flats Plant and to compare241Am concentrations obtained using in-situ and laboratory gamma spectroscopy measurements to concentrations determined with radiochemical analysis and alpha spectroscopy. Soil samples were collected for radiochemical and laboratory gamma spectroscopy analysis from vertical profiles in 3 cm layers to a depth of 21 cm at predetermined locations along transects oriented in the direction of prevailing winds. The origin for the transects was the center of the 903 Pad at the Rocky Flats Plant, which is believed to be the source for most of the241Am and239Pu contamination. A 100 minute in-situ gamma spectroscopy measurement was made at each soil sample location with a portable HPGe detector. Soil samples were dried, passed through a 2 mm sieve, mixed, and split in two fractions. One fraction was analyzed radiochemically for241Am and239Pu and the second was analyzed using laboratory gamma spectroscopy. The median ratio of241Am to239Pu activities, which appears to be independent of soil depth and distance from suspected sources, was 0.17. There is a strong correlation between241Am and239Pu concentrations determined using radiochemical analysis with alpha spectroscopy and concentrations determined with laboratory gamma spectroscopy. Results from in-situ gamma spectroscopy measurements were also correlated with the radiochemical analyses but exhibited greater variability than laboratory measurements. This on-going investigation has demonstrated that it is possible to indirectly measure239Pu concentrations in soil if the ratio of241Am to239Pu can be established. The results indicate that judicious use of a combination of radiochemical analyses with laboratory and in-situ gamma spectroscopy measurements may provide a cost-effective approach for characterization of large sites where241Am and239Pu contamination occur.  相似文献   

20.
Plutonium isotope concentrations in the surface air at Tsukuba, Japan are reported during the period from 1981 to the end of 1986. The239,240Pu concentration in the surface air, which showed a marked seasonal variation with a spring maximum and fall minimum, decreased until the end of 1985 according to the stratospheric residence time of 1.15 years. In May 1986, elevated239,240Pu concentrations with high238Pu/239,240Pu activity ratios were observed. The serial trend of plutonium concentration in the surface air is similar to the concentrations of the Chernobyl-released radionuclides. These findings suggest that a significant part of the plutonium in the surface air in May 1986 was due to the Chernobyl fallout. The size distribution of plutonium bearing particles indicates that plutonium isotopes were mechanically released in the Chernobyl accident. The surface air concentration of plutonium from the Chernobyl accident was much lower than the concentrations of the volatile fission products, and increased the monthly mean239,240Pu concentration by only 0.03 Bqm–3.  相似文献   

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