Distribution Patterns Of Radionuclides Research Articles

Distribution of Radionuclides in the Surface Covering of the Barun Uranium Mining Area in Erlian Basin, Inner Mongolia

In order to identify the distribution pattern of radionuclides in the surface soil in the area of a sandstone-type uranium deposit, and to explore its spatial relationship with the location of the orebody, soil radon measurements and ground gamma-ray spectroscopy were carried out in the Barun study area, and soil properties were analyzed. The results show that the soil radon concentrations exhibited a bimodal feature, while the uranium content showed a decreasing trend along the tendency direction of the orebody. In the ground projection area of the orebody, radon concentration showed a positive correlation with uranium content, with both showing relatively low values. Combined with the results of field geological observation and soil property analysis, it is believed that the relatively low radon concentration and uranium content above the orebody is related to the soil being mainly sandy soil. Relatively high uranium values are distributed within approximately 1.5 km north of the northern boundary of the orebody and near the southern boundary of the orebody. High-value radon anomalies occur within about 2 km north of the northern boundary of the orebody and within about 1.3 km south of the southern boundary of the orebody.

Analysis of the impact of various vertical release patterns on the atmospheric dispersion and total deposition of 137Cs from Chernobyl Nuclear Power Plant accident.

The Chernobyl Nuclear Power Plant (NPP) catastrophe of 1986 has been a milestone in the use of nuclear power for energy generation. After the accident, various topics have been discussed to evaluate the details of occurrence of the event and to understand its impacts on human, animal and plant life. One of the most controversial topics is the release height and homogeneity of radionuclides at release point in the atmosphere. Currently, there exists no definitive decision on the release height and vertical distribution pattern of radionuclides released from the Chernobyl accident. Based on this premise, this study focuses on the analysis of various possible release patterns along the vertical dimension and the potential influences on the atmospheric dispersion and total deposition with particular reference to 137Cs. For this purpose, some release pattern functions following uniform, Dirac delta, exponential, log-Pearson type III, and cumulative distribution functions along the z-axis were used to simulate the dispersion of 137Cs released from the accident site. A total of 22 release patterns are produced using different maximum release heights (2000, 3000, and 4000 m). A Lagrangian particle dispersion model, FLEXPART, was then used to conduct simulations for these conditions to assess most coherent dispersion and deposition patterns. Model results from each release function were plotted, compared with each other and verified with measured data. In the functions where the release predominantly existed at lower levels, more extreme values were observed in the close vicinity of the source. Consequently, Dirac delta, log-Pearson type III (1), and exponential functions can be used as worst-case conditions at local scale. On the other hand, simulations also revealed that contamination spread to wider areas in cases where the release occurred from higher levels of the atmosphere. Therefore, log-Pearson type III (2) and cumulative distribution function can be considered more significant concerning a wider distribution of affected areas.

Natural radionuclides in bottom sediments of the saline lakes. What factors determine their concentration?

Concentrations of 226Ra, 40K, 210Pb, 234Th, 238U, 232Th, and 210Po were determined in bottom sediments of 11 Crimean saline lakes. From lake to lake, concentration of all radioisotopes and their total amount varied. The greatest variability was noted for 226Ra (CV = 1.268), and the smallest for total sum of radionuclides (CV = 0.336). In all lakes, the concentration of studied radionuclides did not exceed the maximum concentrations found in bottom sediments of water bodies in different regions excepting Lake Sasyk-Sivash where 226Ra concentration was slightly higher than previously found the upper limit. There are the inter-lake differences and temporal changes in radionuclide concentrations in the bottom sediments. Salinity is not main determinant of radioisotope concentrations in the lake bottom sediments, but may modify their concentrations in some ranges. The behavior of 210Pb and 210Po under anoxic conditions differs from observed in oxic. Authors conclude that there is no any single factor itself controlling concentrations of radionuclides in the upper layer of bottom sediments in the saline lakes; there is multicausal determination. Only coupling of many factors (physical, chemical, and geochemical properties of radioisotopes, and geological, climatic, and biological) determines radionuclide distribution patterns.

Radionuclide distributions in Olympic Dam copper concentrates: The significance of minor hosts, incorporation mechanisms, and the role of mineral surfaces

Some iron oxide-copper-gold (IOCG) deposits contain variable amounts of uranium. Developing mineral deportment models for the radiogenic isotopes resulting from decay of 238U presents a singular technical challenge, as concentrations of 226Ra, 210Pb, and 210Po fall far below the detection limits achievable for most in situ analytical methodologies. The nanoscale secondary ion mass spectrometry (nanoSIMS) platform combines low detection limits with sub-micron resolution, revealing previously unseen spatial distribution patterns of radionuclides (RNs) in (and on) particles of copper sulphide concentrates. Many potential host minerals for these radionuclides can be readily predicted based on chemical behaviour, periodic table trends, and published studies documenting likely host minerals. Using nanoSIMS data for ores and metallurgical products from the Olympic Dam IOCG deposit and associated processing facilities, we present compelling evidence for the ability of certain minerals within the copper concentrates to host daughter radionuclides derived from uranium decay. Many of these minerals had not traditionally been considered or previously documented as such. These include high-abundance minerals hosting low concentrations of radionuclides, and several relatively low abundance minerals exhibiting remarkable radionuclide enrichment. Rutile, fluorapatite, fluorite, hematite, zircon, covellite, and molybdenite are all proven to be minor hosts of at least some members of the 238U decay chain, and are, collectively, important for establishing the overall RN budget. Surface effects are found to play a significant role, with elevated levels of 226Ra and 210Pb found on most available surfaces, irrespective of mineral, in acid-leached concentrate. Some rRNs, particularly 226Ra and 210Pb liberated from uranium minerals during sulphuric acid leaching, can become extensively redistributed throughout the concentrate, creating newly-formed RN hosts. This new mineralogical deportment information can be used in developing new flowsheets to enhance radionuclide removal without a corresponding loss of Cu. NanoSIMS has proven invaluable for elucidating the mineral-scale deportment of ultra-trace radionuclides throughout the processing circuit at Olympic Dam.

Comportamento de Cs e Co em Sedimentos Marinhos da Enseada de Piraquara de Fora - Angra dos Reis

As a result of discharging of liquid effluents of the Angra dos Reis power plants, 137 Cs and 60 Co radionuclides are the greatest contributors to increasing of radioactivity level in the sediments of the Saco de Piraquara de Fora (SPF) inlet. The thermodynamic and kinetic of sorption of the two radionuclides in sediments of the impact area from the effluent liquid discharge were study to investigate their role in the radionuclide distribution patterns and trends. Cobalt sorption is slightly higher than the cesium one, but mostly both distribution coefficient values were lower than the literature data, which could be ascribed to the predominance of the kaolinite clay in the sediments. For both metals the sorption was higher onto the sediment with the highest cation exchange capacity. Although the velocities of sorption are slow for both metals, both may accumulate in considerable amount in sediments and their sorption is irreversible: 60 Co and 137 Cs accumulate in orders of magnitude of 10 10 and 10 9 Bq g -1 sediment , respectively, which shows the ability of the sediments to adsorb much of the radionuclides released by the power plants. In the range of SPF water temperature, as much the sorption as the desorption of the two metals increase with temperature; however, in general, the retention rate of the metals in the sediments remain constant. The sorption sites are heterogeneous as the sorption data could be fitted by the Langmuir and Freundlich isotherms. The process of sorption of Co and Cs is endothermic, which is spontaneous at low temperature.

Assessment of Natural Radioactivity and Radiological Hazards in Brick Samples Used in Tiruvannamalali District, Tamilnadu, India, With a Statistical Approach.

The activity concentration of Ra, Th and K in brick samples used in Tiruvannamalai District of Tamilnadu has been determined using gamma ray spectrometry. The activity concentration ranges from BDL to 16.02 Bq kg, 17.86 to 120.19 Bq kg, 240.09 to 481.35 Bq kg for Ra, Th, and K, respectively. The concentration of these radionuclides is compared with reported data from other countries. The radium equivalent activity (Raeq), absorbed gamma dose rate (DR), annual effective dose rate (HR), annual gonadal dose equivalent (AGDE), criteria formula (CF), representative level index (RLI), activity utilization index (AUI), gamma index (Iγ), alpha index (Iα), the external hazard (Hex), and internal hazard (Hin) indices are calculated for the measured samples to assess the radiation hazards due to the use of these materials in the construction of dwellings. Multivariate statistical techniques (Pearson correlation, principal component analysis and cluster analysis) are used to study the relation between radionuclides and radiation hazards. The treatment of 14 radioactive variables sampled at 32 bricks by the factor and cluster analyses provided a possible interpretation of the collective data. The spatial distribution pattern of radionuclides has been depicted through the Kriging method using MapInfo software.

Distribution of radionuclides in surface seawater obtained by an aerial radiological survey

We investigated the distribution in seawater of anthropogenic radionuclides from the Fukushima Daiichi Nuclear Power Plant (FNPP1) as preliminary attempt using a rapid aerial radiological survey performed by the U.S. Department of Energy National Nuclear Security Administration on 18 April 2011. We found strong correlations between in-situ activities of 131I, 134Cs, and 137Cs measured in surface seawater samples and gamma-ray peak count rates determined by the aerial survey (correlation coefficients were 0.89 for 131I, 0.96 for134Cs, and 0.92 for137Cs). The offshore area of high radionuclide activity extended south and southeast from the FNPP1. The maximum activities of 131I, 134Cs, and 137Cs were 329, 650, and 599 Bq L−1, respectively. The 131I/137Cs ratio in surface water of the high-activity area ranged from 0.6 to 0.7. Considering the radioactive decay of 131I (half-life 8.02 d), we determined that the radionuclides in this area were directly released from FNPP1 to the ocean. We confirm that aerial radiological surveys can be effective for investigating the surface distribution of anthropogenic radionuclides in seawater. Our model reproduced the distribution pattern of radionuclides derived from the FNPP1, although results simulated by a regional ocean model were underestimated.

THE ASSESSMENT OF RADIONUCLIDE DISTRIBUTION IN SILEX BY AUTORADIOGRAPHY IN THE CONTEXT OF DOSE RATE DETERMINATION FOR THERMOLUMINESCENCE DATING

A combination of two autoradiography methods was applied to investigate the radionuclide distribution patterns in a range of different silices. We obtained greyscale images (β‐radiation) and α‐track patterns for qualitative assessment, and used a statistical approach to quantify the degree of uniformity of the radiation fields. It was found that almost all samples are poor in potassium, thorium and uranium, and that locally high concentrations are present only in dark‐coloured veins and inclusions. Statistical analyses reveal evidence of radionuclide clustering in more than half of the 21 specimens. Concerning thermoluminescence dating of burnt lithics, such gradients should be taken into account to improve precision and accuracy in cases where the external radiation is not strongly dominating for the sample under consideration.

Disequilibrium between uranium and its progeny in the Lake Issyk-Kul system (Kyrgyzstan) under a combined effect of natural and manmade processes

The Kadji-Sai abandoned field of U-bearing brown coal on the southern coast of Lake Issyk-Kul (Kyrgyzstan) poses a threat of radioactive pollution to the world's fifth deepest and second largest pristine highland lake. The valleys of ephemeral streams in the lake catchment are filled with coarse-grained sand and clay, with a background U–Ra activity of 35–55 Bq kg −1. High activity areas vs. this background come from three sources: (1) scarce outcrops of uraniferous brown coal and mining wastes containing fragments of this coal with 238U/ 226Ra ratios of 0.8 due to uranium losses through weathering; (2) manmade anomalies caused by a radioactive waste dump, where U was extracted from the ash of coal burnt at a coal-fired power plant. As a result, the 238U/ 226Ra ratios become 0.15–0.25; (3) six catch pools terraced below the mine, where U activity decreases downslope, and 238U/ 226Ra ratios reach 150–200. Uranium lost in the extraction process may have been retained on the terraces. The distribution pattern of radionuclides in the bottom sediments of the lake is controlled by water depth and offshore distance. The upper section of homogeneous limy–argillic deposits in the lake center remains undisturbed by currents, as indicated by regular sub-exponential distribution of atmospheric 137Cs and 210Pb atm. Sedimentation rate in the lake center for the past century, found from 210Pb, was 0.32 mm yr −1. 238U/ 226Ra in deep-water sediments was about 3. The activity of uranium adsorbed by sediments from the lake water was estimated by subtraction of the Ra-equilibrium component from the total U activity. Thus, the flux of dissolved U to the bottom sediments was as 2.07 × 10 −7 g cm −2 yr −1. The upper section of near-shore deposits was disturbed by currents, with 137Cs and 210Pb atm more or less uniformly distributed in this layer. Peaks of 226Ra and 210Pb occur at different depths from 5 to 20 cm below the sediment surface, with 238U/ 226Ra ratios 0.28–0.44. The presence of mullite in these sediments indicated that radioactive ash penetrated into the lake in the past. At present, 226Ra in the ash is buried under a non-radioactive cap.

Microdosimetry to Leukaemogenic Target Cells for Bone-Incorporated Alpha-Emitting Radionuclides

Neutron-induced autoradiographs of femoral bone shafts taken from mice injected with 40 kBq.kg -1 239 Pu, 241 Am or 233 U, 1, 28 or 224 days previously. were analysed morphometrically in order to present a comparison of the changing radionuclide distribution patterns. Microdosimetric methods were used to calculate localised dose rates throughout the bone marrow, and hence to those cells thought to be target cells for leukaemia induction. Initially all three radionuclides were found to be primarily deposited on the endosteal and periosteal surfaces of the bone. 241 Am was additionally deposited on the surfaces of the vascular canals. 239 Pu subsequently became either buried in the bone matrix or resorbed into macrophages, which by 224 days were seen to have migrated towards the central venous sinus. 241 Am deposits were also present in macrophages, but to a lesser extent. In contrast uranium was not taken up into macrophages. Mean dose rates to the axial region of marrow, believed to contain the leukaemogenic target cells, were calculated for plutonium as 0.11, 0.07 and 16.78 mGy.d -1 and for americium as 0.23, 5.19 and 2.28 mGy.d -1 at 1.28 and 224 days respectively. For uranium a dose rate of zero was calculated at all time points.

Speciation of 137Cs and 90Sr in discharges from the pulp industry and the marine recipient

The concentrations and size distribution pattern of radionuclides in waste-water discharges from a pulp industry located at the Oslo fjord, Norway, have been studied. The annual discharge to the fjord amounts to about 1.9 GBq for 137Cs and 2.7 G Bq 90Sr. Information on the size-distribution pattern of 137Cs and 90Sr in discharge waste water and the marine recipient was obtained using tangential cross-flow ultrafiltration technique. Caesium-137 was measured with Ge-detectors, while 90Sr was determined using a low-level scintillation spectrometer. Almost all 137Cs in discharge waste water was found to be present in the low molecular weight fraction. The major fraction of 90Sr in discharge waste water was present in the low molecular weight fraction, while a significant fraction was found as colloids. Almost all 90Sr in seawater was present in the low molecular weight fraction. Due to transporting currents and dilution, no radiological impact on the receiving coastal waters could be observed.

Radiometric investigations of Kara Sea sediments and preliminary radiological assessment related to dumping of radioactive wastes in the Arctic Seas

There has been world-wide concern over the possible health and environmental impacts of the dumping of radioactive wastes in shallow waters of the Kara and Barents Seas. During 1992, IAEA-MEL participated in a joint Russian-Norwegian expedition to the region and collected a suite of sediment cores for characterization of downcore radioactivity distribution patterns and inventories with the aim of assessing past and present inputs of radionuclides. The 137Cs, 238Pu, 239,240Pu, and 241Am contents of the 0–1 cm sections range from 17 to 32, 0·01 to 0·06, 0·4 to 1·3 and 0·2 to 0·5 Bq kg−1 (dry wt), respectively. The 238Pu/239,240Pu and 241Am/239,240Pu activity ratios are consistent with those reported for global fallout. Detailed information on downcore radionuclide distribution patterns and inventories, as well as an account of sedimentation parameters, are presented.A preliminary assessment of the long-term radiological impact of radioactive waste disosal in the Arctic Seas, on global and regional scales, has been made. The modelling results suggest that the global radiological impact of the disposals will be comparable to or less than those resulting from other anthropogenic and natural sources of radioactivity. However, radiological effects on the regional scale may be of importance.IAEA is carrying out a 4 year International Arctic Seas Assessment Project (IASAP) that will comprehensively cover all aspects of radioactive dumping in the Arctic Seas and it will be reported to the London Convention in 1996. The IAEA-MEL study described here represents a preliminary contribution to IASAP.

Distribution of Long‐Lived Radionuclides in an Abandoned Reactor Cooling Reservoir

The distribution of 137Cs, 90Sr, 238Pu, 239, 240Pu, 241Am and 244Cm was studied in the biotic and abiotic components of an abandoned reactor cooling impoundment, Pond B. The impoundment is located at the United States Department of Energy's Savannah River Plant in South Carolina, USA. It received radioactive contaminants via cooling water discharges from R Reactor from September 1961 to June 1964. The radionuclide inventories were estimated in water, seston, sediments, and biotic components after 20 yr of equilibration. Chemical, physical, and biological relationships to the radionuclide distribution patterns were investigated. Biotic components contained some of the highest radionuclide concentration ratios observed to date. However, most of the radioactivity resides in sediments. The principal mechanisms of loss from the system are radioactive decay and periodic outflow of water and suspended materials; biotic export and seepage appear to be inconsequential. Strontium—90 was much more mobile in the system than the other radionuclides. Aquatic macrophytes dominated the biotic component radionuclide inventories and their dynamics exert a strong influence on the spatial distribution and turnover of radioactivity in the ecosystem. Pond B supports a diverse and productive flora and fauna. Cleanup of the system is not indicated. Use of Pond B for recreation is feasible with adequate attention to monitoring and radiological health guidelines.

Determination of radionuclides associated with colloids in natural waters

Due to the interaction with components present in natural waters, radionuclides may be present in different physico-chemical forms, varying in size, charge and density. The distribution pattern will influence the transport, mobility and biological uptake of the radionuclides. Size fractionation based on hollow fiber is useful for the determination of the size distribution pattern of radionuclides in natural waters. Furthermore, a continuous mixing and separation system has been developed for the investigation of the association of radionuclides with naturally occurring colloids. Results based on radionuclides in waste water from the Forsmark nuclear power plant, Sweden, will illustrate the potential usefulness of the technique.

Therapeutic intraperitoneal 32P: a clinical assessment of the dynamics of distribution.

With an Anger camera for scintigraphic recording of bremsstrahlung radiation from phosphorus-32, the distribution of intraperitoneal colloidal chromic phosphate was followed in patients with gynecologic tumors. Sequential pelvic, abdominal, and thoracic scintiphotos over a three-week period revealed rapid and persistent focal aggregation of the radiocolloid with no change in pelvic or peritoneal radionuclide distribution patterns. Visualization of intrathoracic lymph node uptake did not correlate with the presence of diaphragmatic tumor. This study demonstrates the utility of scintigraphy for monitoring the distribution of intraperitoneal beta emitters and the need for developing alternative methods of administering these therapeutic agents to achieve more uniform patterns of distribution.

Roles of food and sea water in the accumulation of radionuclides by marine fish.

As a part of study on accumulation of radionuclides by marine fish, yellowtail, were marked by multiplc radloisotopes (144Ce-144Pr, 106Ru-106Rh, 85Sr, 137Cs, 54Mn, 65Zn and 60Co) under certain con-ditions through food and water. The radioactivity of each tracer in the tissues or organs was determined by a Ge(Li) spectrometer in order to gain more knowledge concerning roles of food and water in the accumulation of radionuclides. Somewhat different distribution patterns of radionuclides were found in the whole bodies of the fish at the maximum accumulation with the difference in pathways. The results obtained in the excretion experiment for two weeks suggested that the turnover rate was different, depending on pathways through which the fish accumulated radionuclides. And the principal pathway in the accumulation of radionuclides by marine fish in natural sea was esti-mated. The results showed that (1) food rather than water supplied most of the 65Zn and 54Mn accumulated by fish, (2) 85Sr and 106Ru-108Rh were mainly accumulated via water and (3) the two pathways played almost the same role in the accumulation of 137Cs, 60Co and 144Ce-144Pr. Therefore, it is necessary to take into account these results for estimation of the extent of radioactive contamination in fish under natural marine ecosystem.

Characterization of malignant gliomas and cerebrovascular disease by cerebral dynamic studies.

A technique for analysis of dynamic radionuclide studies of the cerebral circulation is described. This technique permits objective classification of observed radionuclide distribution patterns. Variation in the time-to-peak activity, and in the maximum attained activity as determined by region-of-interest analysis of cerebral hemispheric activity, was defined for a normal population. Application of these normal values permits classification of observed hemispheric radionuclide distribution patterns in anaplastic gliomas and in occlusive cerebrovascular disease. Radionuclide activity in gliomas may be normal, decreased, or increased in the region of the tumor. In cerebrovascular occlusion, decreased activity, associated with a delay in time-to-peak activity, is frequently demonstrated in the affected hemisphere.