No abstract available

No abstract available

[en] Acid mine drainage (AMD) is a world wide problem that occurs whenever sulfidic material is present in association to the mined ore. The acidic waters generated by the process of sulfide minerals oxidation can mobilize important amounts of pollutants and cause significant environmental impacts. The composition of the drainage will depend, on a very large extent, on the mineralogy of the rocks. The purpose of this paper is to demonstrate that acid mine drainage has the potential to enhance the natural levels of environmental radioactivity. The paper revises some strategies to be used in the diagnostic of the problem. General mathematical formulations that can assist on the prediction of the duration of the problem, and the definition of the size of the oxidizing zones in a waste dump are given. A study case on a waste dump of the Pocos de Caldas Uranium Mining Site, Brazil is also presented. (author)

[en] Acid Rock Drainage is of great concern to environmental regulators and mine operators in many countries around the world. During the operational life of an installation, the collect and treat strategy is a commonly employed strategy to reduce pollutant emissions to the environment. Regarding the post-operational scenarios a suite of different strategies is available in the literature. Acid drainage is a crucial problem at the uranium mining and milling site of Pocos de Caldas. Two waste-rock piles (of about 60 ha each) resulted from mining activities. Presently acid waters are being collected and neutralized, the solid material being disposed in the tailings dam. The Institute of Radiation Protection Dosimetry, has developed studies that concluded that a permanent solution to the problem should favor covering the dumps with a three layered cover system. However if the uranium average concentration in the drainage (about 10 mg/L) is taken into consideration, its economical recovery may be thought about. This strategy will imply in the recovery of 30 tons U₃O₈ per year - representing c.a. 30% of the mean annual production of the installation. The recovery would include the use of ion-exchange resins. The technical and economical viability of the strategy as well as technical and economical issues concerning the application of a dry cover to the waste rock piles will be presented and discussed in detail. (author)

[en] Presently, the known uranium resources of Brazil amount to 262,200 tU as recoverable conventional sources producible below US$ 80/kgU. The Pocos de Caldas production centre ceased its operation in 1997 and a production facility with a capacity of 300 t U₃O₈/year is planned to start operation in 1999. It will be sustained by known resources recoverable at costs of up to US$ 80/kgU. Brazil's present uranium requirement is about 120 tU/year. With the completion of the second nuclear power plant the requirement will increase by 250 tU per year, beyond the first core which would demand 560 tU. Different non-uranium mining activities present high concentrations of uranium associated to the main ore. These include three major sources: one, where uranium occurs associated to phosphate and plants where uranium occurs associated to pyrochlore (Nb ore). Recovery of uranium from these installations has the potential to increase the Brazilian production significantly and will play a key role in the case of the construction of the third nuclear power plant. (author)

[en] It is well known that the need for extensive remediation programmes derives from the lack of appropriate planning at the beginning of mining operations, i.e. remediation is not adequately taken into consideration in the overall mining development. As a consequence of this, the implementation of remediation work generally faces several constraints that prevent the adoption of the necessary cleanup procedures. These constraints can be of an economic, technical, regulatory or social nature. In Brazil, the remediation of the uranium mining site of Poços de Caldas constitutes a very significant challenge for the mine operator and regulatory organizations. Many research/technical projects have been carried out by different institutions but the integration of the results of these works into a coordinated framework has never been achieved. There is also a lack of synergism between the environmental and nuclear regulatory authorities, and the mine operator does not seem to have a clear plan of action to deal with the problem. As a result of this situation, the expertise existing in the country is not being properly utilized to facilitate the development of the necessary actions. Also, members of the public have not yet been properly involved in the decision making process and this will constitute a serious problem in the near future. The paper discusses potential actions to overcome these constraints based on international experience. (author)

[en] Acid rock drainage generated as a result of sulfitic minerals oxidation is a source of pollution in many mining sites all around the world. This is the case at the uranium mining site of Pocos de Caldas, Brazil. The present study was aimed at studying the geochemical mechanisms involved on the mobilization of radionuclides from the waste rocks that occurs along with the acid drainage. The environmental radiological impacts caused by these pollutants were also assessed. It has been shown that precipitation of Ra and Pb as sulfates was the most important mechanism in the reduction of both radionuclides activity concentration in the acid drainage. A result of this study was that uranium isotopes were the most important radionuclides in terms of the exposure of the critical group. It has been suggested that the recovery of uranium from the acid drainage would be a feasible practice, economical aspects taken into account. It has also been estimated that pyrite oxidation will occur for more than a thousand years. The long time scale involved on the oxidation of the pyritic material implies the need for the adoption of permanent remedial actions. To assess applicable remediation strategies it has been suggested that oxygen and temperature profile determinations should be carried out in the dump

[en] This geochemical modeling work was carried out to simulate the acid drainage generation from one of the waste-rock piles at the Pocos de Caldas uranium mining site. The mathematical code STEADQYL was used. The estimated results were in good agreement for sulphate and uranium concentrations and the duration of the acid water generation was estimated to be about 500 years. The effect of covering the dump with a material that minimized oxygen diffusion was assessed. Projections indicated that covering the dump with a 1.0 m thickness of a material (like clay), which had an oxygen diffusion coefficient of 10⁹m²·s¹, would reduce the pollutant concentrations to acceptable values. The estimated cost, when using this strategy, would be about US $10 million. (author)

[en] This paper discusses the difficulties in applying the prevailing radiation protection concepts in dealing with TENORM issues. The Brazilian experience is presented and the regulatory framework is presented. It is concluded that exemption criteria may not be the best way to address activities involving such kind of materials, although they may serve as reference values, along with dose estimates, to determine the extent in which individual TENORM industries shall be subjected to environmental impact assessment protocols. (author)

[en] Attitudes of different communities against uranium mining can impose severe constraints in uranium mining operations, potentially leading to insuperable barriers to project implementation and development. Some studies have investigated public opinion on uranium mining in different countries. One of these studies in Australia revealed that in 2008 just under half of the public supported the mining of uranium, while 36% opposed it. The study also informed that over the previous decades, public support for nuclear energy in Australia had declined, while support for uranium mining had remained relatively stable. In Canada, a study prepared by AREVA Resources indicated that 'the uranium mining and uranium mining companies continue to hold a place of importance in the minds of Saskatchewan residents. Support remains high among survey respondents, both province-wide and in the North... as the result of the perception... that the primary companies operating in the industry operate safely and responsibly, and contribute positively to the province'. A study developed by the University of Eastern Finland, Litmanen and others indicated that public opinion was more critical of uranium mining operations in comparison to other types of mining activity such as (other) metals and industrial minerals. Only 1-4% of the interviewed individuals considered these activities as being unacceptable, while in the case of uranium mining this level was determined to be between 38 and 51%. Six variables were examined in the study: environmental attitudes, perceptions of the disadvantages and benefits, knowledge of the mining, trust, trust in officialdom and acceptability of foreign mining companies. Familiarity with operations correlated strongly with the acceptance. Drawbacks have a stronger impact on acceptability than have the benefits. Trust in the authorities and legislation is strongly and positively correlated with acceptance. Finally, it was seen that the people who are more willing to accept foreign mining companies were also those more inclined to accept uranium mining. Regarding Africa's situation, the place of the continent in the global nuclear market was examined in 2012. This study considered that international and African tools either exist or are being set up to improve the governance of uranium mining in Africa. It concluded that improvement requires attention to strengthening government capacity and ensuring wider consultative processes.