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[en] The sixth IAEA Technical Committee Meeting on Energetic Particles in Magnetic Confinement Systems was held in Naka, Japan, 12-14 October 1999. The meeting was attended by over 60 participants from 10 countries and 3 international organizations. This conference report contains summaries on energetic electrons, experiments on energetic ions and theory. The seven invited papers are published in this special issue of Nuclear Fusion
[en] An investigation has been made to study the properties of large-amplitude electrostatic solitary waves in dusty plasma containing both negatively and positively charged dust fluids in the presence of superthermal electrons and ions. The energy balance equation is derived by using the Sagdeev pseudopotential approach. The influence of the physical parameters (e.g., superthermality of electrons or ions, density concentration of positive and negative dust particles, solitary speed) on the amplitude of dust acoustic solitary waves has been discussed in detail. It is observed that there exists a critical value of density, below which negative potential solitary structures exist and above which positive potential solitary structures exist. (author)
[en] A cost-effective method for treating contaminated soil 'in situ' using low temperature oxidation (LTO) to convert the hydrocarbons to inert coke, is discussed. Low temperature oxidation of a wide variety of hydrocarbons in the presence of core material and water has been investigated previously using plug flow reactors. For Athabasca bitumen, it was found that more than 80 per cent of the initial oil was converted into coke after only a few hours of injecting oxygen/nitrogen mixtures with less than 10 per cent oxygen content at temperatures ranging from 150 degrees C to 275 degrees C. Increasing the oxygen content in the gas and increasing reaction time would, presumably further augment the conversion of hydrocarbons to coke. The method is particularly well suited for remediating flare pits. 5 refs., 7 figs
[en] Some preliminary results of the effects of moisture content on volume emanation rates and emanation coefficients are presented for core and crushed samples of cemented tailings. The volume emanation rates increased with increasing moisture content, with saturated core samples emanating about 3 times as much as dry material. There was a similar increase in coefficient for the crushed cemented tailings
[en] COGEMA Resources Inc. (which is part of the Areva Group) is a Canadian company with its head office in Saskatoon, Saskatchewan. It owns and operates mining and milling facilities in Northern Saskatchewan, which produce uranium concentrate. McClean Lake Operation commenced production in 1999 and its tailings management facility represents the state of the art for tailings management in the uranium industry in Canada. Tailings disposal has the potential to cause effects in the surrounding receiving environment primarily through migration of soluble constituents from the facility to surface water receptors. In-pit disposal or mill tailings has become the standard in the uranium mining industry in Northern Saskatchewan. This method or tailings management demonstrates advances in terms of worker radiation protection and containment of soluble constituents both during operations and into the long term. Sub-aqueous deposition of tailings protects personnel from exposure to radiation and airborne emissions and prevents freezing of tailings, which can hinder consolidation. The continuous inflow of groundwater to the facility is achieved during operations, through control of water levels within the facility. This ensures hydrodynamic containment, which prevents migration of soluble radionuclides and heavy metals into the surrounding aquifer during operations. The environmental performance of the decommissioned facility depends upon the rate of release of contaminants to the receiving environment. The rate of constituent loading to the receiving environment will ultimately be governed by the concentrations of soluble constituents within the tailings mass, the mechanisms for release from the tailings to the surrounding groundwater system, and transport of constituents within the groundwater pathway to the receiving environment. The tailings preparation process was designed to convert arsenic into a stable form to reduce soluble concentrations within the tailings mass. The design of the TMF itself relies on the high permeability sandstone unit to provide a preferential flow path for groundwater around the low permeability tailings mass. This provides a passive means of minimizing the long-term release of constituents from the decommissioned facility to the environment. A comprehensive tailings optimization and validation program was developed to reduce uncertainties related to the performance of the tailings management facility associated with the chemical and physical properties of tailings. This paper will describe the JEB tailings management facility and provide a summary of the findings of this research program. (author)
[en] The results from the study of modern geochemical conditions in the tailing Centralny Yar and determination of speciation of Uranium in terms of its mobility in tailing material using modified BCR sequential extraction protocol are presented.
[en] Energetic electron driven toroidal Alfven eigenmodes (TAEs), which have been observed in many devices (COMPASS-D1, C-MOD2, HL-2A) with high-power ECW and LHW heating, are investigated using a hybrid simulation code MEGA in a tokamak plasma. Considering the interaction between energetic electrons and Alfven eigenmodes, energetic electron effects on TAE excited by energetic ions are further investigated, as active control of Alfven eigenmodes using ECH can also produce a considerable number of energetic electrons. Firstly, an energetic electron driven TAE propagating in the electron diamagnetic drift direction is found using MEGA.
[en] An ElectroMagnetic Solver (Chen et al 2006 Phys. Plasmas 13 123507) is employed to model a spectral gap and a gap eigenmode in a periodic structure in the whistler frequency range. A radially localized helicon mode (Breizman and Arefiev 2000 Phys. Rev. Lett. 84 3863) is considered. We demonstrate that the computed gap frequency and gap width agree well with a theoretical analysis, and find a discrete eigenmode inside the gap by introducing a defect to the system's periodicity. The axial wavelength of the gap eigenmode is close to twice the system's periodicity, which is consistent with Bragg's law. Such an eigenmode could be excited by energetic electrons, similar to the excitation of toroidal Alfvén eigenmodes by energetic ions in tokamaks. Experimental identification of this mode is conceivable on the large plasma device (Gekelman et al 1991 Rev. Sci. Instrum. 62 2875). (paper)
[en] The mining and milling of uranium ore are produced in Ukraine since 1948. During this time eleven tailings were formed at the large territory in the region of cities Zhovty Vody and Dnepropetrovsk. One tailing is now in operation. Other ten tailings are under conservation and are producing environmental impact of different extent. Any of tailings was not subjected to recovery. By means of the enterprises, which have on their territory tailings, the monitoring is carried out for radionuclides coming in underground waters. The samples of underground water are taken from wells that are located at the tailing perimeter. The list of tailings, quantity of stored material, and radionuclides activity are submitted in the table. The supervision shows, that all tailings to some extent are the issue of radionuclides diffusion. The brief characteristic of the largest tailings is submitted. The supervision shows that all tailings to some extent are the issue of radionuclides diffusion. The brief characteristic of the largest tailings is submitted. Most of tailings are located in natural folds of a region relief, however one of them (KBG) is arranged in career with depth 60-65 m. Iron ore was mined in this career and career is located on distance 2.5 km from an inhabited zone. Career was not equipped by anti filtration barriers before it was started to fill it with sludge. In total 12.4·106 m3 of tails is placed in it with general activity about 1 PBq. When tailing's filling was finished at 1991 its surface was covered by 1,7 m layer of loamy soil. The tailing creation resulted in change of hydro-geological conditions of a platform and in appearance of man-caused water-bearing horizon. The halo of pollution of underground waters is moving from the bounds of the site towards the inhabited zone of Zhovty Vody city. Now polluted by radionuclides water is detected at the distance of 1.5 km from tailing. According to forecast estimations in 15 years the pollution will move forward from tailing to distance 2.4 km, i.e. will reach the bounds of an inhabited zone of city Zhovty Vody. Large threat is posed by tailing 'D', that is located in Dneprodzerjinsk city on distance of 1.5 km from the Dnieper river and is containing 5.84·106 m3 of sludge of uranium mining with general activity 630 TBq. The tailing 'D' is covered by phosphogypsum, which general weight is 12·106 tons. The tailing 'D' dam is made from material of final tailings of chemical recovery production and its operating conditions are not properly surveyed. Meanwhile, water samples from wells in the area of tailing 'D' location have the concentration of Ra226 from 1.59 Bq/l till 5.55 Bq/l. Dose rate, that was measured tightly to one of water samples, was 13.1 mGy/h. Underground waters in area of tailing location flow in the direction of the Dnieper river. One tailing is in operation (Shcherbakovsko) that is located in 1.5 km to the south of Zhovty Vody city. Shcherbakovsko tailing is located in a natural gully. Its first section was filled in 1959-1980 years and occupies the area 890 000 m2. The second section is in operation from 1979 and occupies the area 1.390.000 m2. In total 27 · 106 m3 of tailing sludge is stored with general activity 2.22 PBq. Any works for its first section conservation are not carried out. The operation condition of a dam of tailing is under control and each year the works for dam strengthening are carried out. Nevertheless, the part of water is filtering through a dam into underground water horizons. Now halo of pollution of underground waters moved from the tailing to distance 1.8 km and, according to forecast estimations in 15 years this distance will be 3 km. Tailing 'C' also is located in a natural gully and consists of two sections. The first section was filled in 1968-1983 years and occupies the area 160 000 m2. The second section is in operation since 1983 and occupies the area 390 000 m2. In total 12.2 · 106 m3 of tailing sludge is stored with general activity 98 OBq. Four settlements are located near tailing at distance 1.0, 1.0, 2.0, and 3.5 km. Distance up to the Dnieper river is about 4 km. In underground water samples from wells in the area of tailing 'C' location Ra226 is detected in amount exceeding background meanings 10 times and the greatest Ra226 contents is detected in a well on a bank of the Dnieper river. In Ukraine the State program for contaminated areas decommissioning and recovery is adopted. However, in view of suffered by Ukraine economic crisis, this program is suspended. Moreover, the scope and volume of carried out monitoring is insufficient for fulfilling of correct estimation of tailings environmental impact and for correct estimations of the contribution of radiating pollution into public exposure
[en] The production of massive neutrinos by electrons moving in an external field in considered. The small neutrino mass is shown to greatly affect the probability of high-energy neutrino production of ultrarelativistic electrons. An entirely new experimental scheme for the discovery of neutrino mass is suggested and analyzed. 7 refs