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1. THE ROLE AND ACTIVITIES OF THE STATE OFFICE FOR NUCLEAR SAFETY IN URANIUM MINE AND MILL CLOSURES
J. SEDLÄCEK, J. HORYNA
Abstract: Uranium produc tion in Czechoslovakia began in 1946. Cumulative production coming from 20 production centres to the end of 1993 is in the order of 103 000 t U. Almost all of these centres are located in the Czech Republic. At present only two centres are still in operation. The Czech Republic is now confronted with control, monitoring and eventual rehabilitation of these closed centres. The State Office for Nuclear Safety (SONS) is charged with the responsibility of controlling of nuclear safety of all nuclear facilities, including operating and abandoned uranium mines and mills, which was performed previously by the Czechoslovak Atomic Energy Commission (CAEC). Present activities of SONS in this areas have focused on the siting, construction and operation in the storage and transport of uranium concentrate. A number of laws and regulations related to radioactive waste, radiation protection, environmental protection, clean water system, as well as the construction, commissioning and eventual decommissioning of nuclear facilities have already been adopted. Regulations specific for nuclear fuel cycle facilities are under preparation.
2. DECOMMISSIONING AND REHABILITATION OF URANIUM MINES AND MILLS IN GERMANY
D. MAGER
Abstract: With the reunification of the two Germanics in 1990 the Federal Republic of Germany became one of the biggest uranium producing countries in the world. A post-war production of 220,000 metric tonnes of uranium places in Germany in the front line of the uranium producing countries, exceeding by far the post-war production of Australia, South Africa and the Soviet Union. Unlike in other producer countries all mining operations were carried out in a relatively small mining district, approximately 150 km long and 50 km wide, in the southern part of eastern Germany. Especially in the first years of uranium production the then Soviet-owned WISMUT Company carried out mining practically without considering the damage to the environment or humans. The result of 45 years of uranium mining in the states of Saxonia and Thuringia are many square kilometres of contaminated areas and facilities; they were used for a certain period of time for different purposes like intermediate storage, transport, mining and milling of ore as well as the deposition of waste rock and tailings. All these problematic areas are not situated in the remote loneliness of northern territories or deserts like in Canada and Australia, but instead in one of the most densely populated areas of Germany. Since uranium mining is far from being profitable by western standards, the German Federal Government and the Soviet Government came to an agreement to stop mining by the end of 1990. In 1991 a huge decommissioning and rehabilitation programme was initiated with the aim of minimizing ecological hazards and realizing the fast closedown of the expensive underground operations. As in all centrally planned economies the WISMUT Company had not built up any financial reserves. It is now the Federal Government which enables the government-owned WISMUT GmbH by enormous funding of approximately 13 billion German Marks over a project period of 10 to 15 years to carry out the decommissioning and rehabilitation programme. The government sees to it that an optimum is achieved under ecological, financial and social aspects; i.e. the aim of the decommissioning and rehabilitation programmes is to re-establish in the involved areas widely intact ecological conditions. At the same time the economic, industrial and social structures must be kept in a state of balance. For decommissioning and rehabilitation the best available know-how and the international market is integrated. Thereby expertise is concentrated in order to achieve the optimum between ecological benefit and financial input. In the presentation further information will be given on the legal, financial and organizational aspects of the German programme as well as the political issues.
3. DECOMMISSIONING OF US CONVENTIONAL URANIUM PRODUCTION CENTERS
T. CHUNG
Abstract: The Energy Information Administration (EIA) is a quasi-independent Organization within the U.S. Department of Energy (DOE), responsible for collecting, analysing, and disseminating information on energy including the U.S. uranium industry and nuclear power generation. The EIA is also actively involved in assisting the DOE Office of Environmental Restoration and Waste Management to implement the reimbursement of mill tailings remediation costs in compliance with Title X of the Energy Policy Act of 1992. As one of our recent projects, we examined the decommissioning efforts of conventional uranium production centers. This paper summarizes that work. For conventional uranium production centers, decommissioning involves decontaminating and dismantling the mill itself, reclaiming the tailings pile(s), restoring ground water to acceptable conditions, and long term monitoring of the site. In examining these Issues, this paper: (1) presents a brief history of the development of the regulations that govern the industry, (2) describes the decommissioning process for conventional uranium production centers and (3) compares aggregated decommissioning cost data for six selected conventional uranium mills, based on filings with the U.S. Nuclear Regulatory Commission.
4. AUSTRALIAN EXPERIENCE IN THE REHABILITATION OF URANIUM MINES AND MILLS
R.J. RING, D.M. LEVINS, J.R. HARRIES
Abstract: Australia has a long history of uranium mining. In the early days, little attention was given to environmental matters and considerable pollution occurred, particularly at the Rum Jungle site in the Northern Territory. In the 1970's, there was increased community concern about environmental matters which was reflected in the passing of the Environment Protection Act. This Act requires all mining companies to have plans for closure, decommissioning and rehabilitation approved before mine development is commenced. In the early 1980s, the Federal Government provided funds for the rehabilitation of the Rum Jungle site. Since then, two other major uranium mining and milling facilities have also undergone rehabilitation. Currently there are two large uranium mining operations in Australia These mines were developed and operate under strict regulatory control which requires the implementation of best practicable technology to minimize environmental impact. Integration of rehabilitation/decommissioning requirements into operating plans is an essential feature of the long term management of these projects. This paper describes Australia's experience in the decommissioning of uranium mining operations. Careful planning of tailings and water management during the operational phase is essential to simplify and reduce the cost of closure, while still achieving environmental standards.
5. TECHNICAL REHABILITATION OPTIONS FOR FORMER MINING AND MILLING FACILITIES OF WISMUT GMBH
G. LANGE
Abstract: The predecessor company of Wismut GmbH had mined uranium deposits of five different types which varied in their geological settings and sizes. Milling sites also had different geological environments. In contrast to U.S. practice to apply general rehabilitation standards not on a site-specific basis, the German government has opted for rehabilitation targets following site-specific assessment and optimization procedures which take into account the relevant geological and hydrological situation, the mining history and the technologies used. Vein type deposit of Schlema/Alberoda: Cleansing, exploration and backfilling of near-surface historic mine workings. Filling of subsidence area. Mine flooding up to level of historic drainage adit. Treatment of discharge waters for U, Ra, and As over specified time frame, in situ rehabilitation of bulk of waste piles. Perpetual depression ventilation of near surface openings to protect the Schlema community against Rn concentrations. Black shale type deposit of Ronneburg: Controlled flooding of mine up to original ground water level using barriers to separate mine workings having differing contamination concentrations. Treatment of discharge waters. Waste-specific placement of most piles into worked-out open pit. Sandstone type deposit of Königstein: Removal of easily leachable uranium from leaching blocks while neutralizing circulating solution. Flooding of mine subsequent to flushing of deposit using a system of control tunnels in the outskirts of the deposit until compliance. Maximum protection of upper aquifers by sealing all penetrations due to mining. In situ rehabilitation of waste pile. Coal type deposit of Dresden-Gittersee: Flooding of mine up to level of drainage adit from historic coal mining. In situ rehabilitation of waste pile. Deposits occurring in Upper Permian sandstones and limestones: They were exploited by open-cast mining; worked-out open pits were used as tailings ponds. Milling facilities: Hydrogeological investigations of the surroundings of tailings ponds. Seepage collection; treatment and discharge of free water from tailings ponds. Dewatering and encapsulation of tailings in situ. Demolition of contaminated structures and excavation of contaminated soils at all sites.
6. THE URANIUM PRODUCTION CONTRACTION PROGRAMME IN THE NORTHBOHEMIAN CRETACEOUS AREA, CZECH REPUBLIC
J. FIEDLER, J. SLEZÂK
Abstract: The sandstone-type uranium deposits in the northern part of the Bohemian Cretaceous basin (the so-called "Northbohemian Cretaceous") were discovered in the early 1960s. The main occurrence area of such a type of deposits, which are connected with the base part of the upper cretaceous sedimentary complex, is the area of the Strâz block. The main production activities of the Czechoslovak Uranium Industry Company (CSUP) were concentrated in this area in the second half of the 1960s. The Strâz block deposits were considered the most prospective sources to cover the long term needs of the Czechoslovak nuclear programme, which was planned on a large scale. The development of the CSUP production activities was very fast in the area of the Strâz block and unfortunately without future considerations. Two uranium deep mines (DH-1, DK-1) were in production and one uranium deep mine (DH-2) was in the stage of preparation at the end of the 1980s. The approximately 6 km2 ISL production complex was also present beside these classical deep mines. The gradual contraction programme of uranium production in the northbohemian area is connected with the whole Uranium Industry contraction programme and it is caused by:decreasing of the uranium market in the USSR since the end of the 1980s, loss of the Slovak market after the splitting of Czechoslovakia, low uranium demand in the Czech Republic after the previous reduction of the nuclear programme, decreasing of the uranium market apply possibilities abroad (oversupply, great production costs), and re-evaluation of the ecological criterions for the limiting environment load, which is influenced by the uranium production. The contraction programme properly began with the liquidation of the Hamr-2 Mine (DH-2) in the Strâz block at the end of the 1980s. The production of the Krizany Mine was interrupted in 1990 and its liquidation has started. The development of the ISL plant was stopped by government decision in 1991, and its production has been carried on only at the minimum technological level since 1992. A decision about the future of ISL will be made after an evaluation of research and verifying work, which will end in 1994. The last production complex influenced by the contraction programme is the Hamr-1 Mine (DH-1), which has been mothballed since mid-1993. The mine production has stopped and only backfilling is performed. A decision about the next future will be made by the government in 1995, after a complete re-evaluation of the whole contraction programme in the Czech Republic.
7. EXPLORATION, EXPLOITATION AND CLOSURE OF THE KRIZANY MINE (THE BREVNISTE DEPOSIT) IN THE NORTHBOHEMIAN CRETACEOUS, CZECH REPUBLIC
J. SLEZÂK
Abstract: The Krizany Mine was the last newly opened uranium mine in former Czechoslovakia. This mine opened the Brevniste deposit, which was found by the hydrogeological borehole SZ-10 in 1966. Exploration work was done by the Uranium Industry Geological Exploration Company until 1980. The building of shaft No. 4 started in August 1973 and was finished in September 1975. The second shaft on this deposit, shaft No. 5, was built from September 1973 until September 1976. Both shafts were built with a diameter of 4.8 m and with a depth of more than 280 m. The first exploitation rooms were opened in September 1983 and backfilling of the mined-out rooms started in November 1984. Production finished on 30 April 1990 and backfilling in September of the same year. The production of the mine was about 1180 0001 of uranium ore (containing more than 10601 of uranium) between 1983 and 1990. The losses during the milling process were between 5 and 20% and they are not known exactly because of mixing ores from the different mines. The closing of the Krizany Mine was based on the decision of the Czechoslovak Federal Government (No. 94/1989). This dealt with decreasing the financial losses in the Uranium Industry in 1990 and later, using a contraction programme. This paper is based on "The Final Report about the Results of Exploration and Exploitation on the Brevniste Uranium Ores Deposit (the Kriiany Mine) in the Northbohemian Cretaceous", which was done by the Geological Department of DIAMO's division TUU in Stra2 pod Ralskem at the end of 1993.
8. PROGRAMME FOR THE CLOSEOUT OF THE ZIROVSKI VRH URANIUM ORE MINE (REPUBLIC OF SLOVENIA)
M. JERAN
Abstract: In the Republic of Slovenia, the Zirovski vrh Uranium Ore Mine stopped its regular operation in 1990 by the decision of the Government. In July 1992, the Law on permanent closeout of the mine passed and according to this a programme on its closeout is being prepared for the Ministry of the Environmental Protection and Physical Planning. The programme has been presented to the local communities and to the Government. All questionable points have been discussed and resolved in the presence of a local community representative and consequently, the programme was accepted by the Government in April 1994. This programme is the so-called plan document for all the closeout activities and for the project financing. The closeout of the Zirovski vrh Uranium Ore Mine is to be carried out in four technical and technological steps: closeout of the mine, processing plant, tailing and waste rock piles, and monitoring of the environmental impacts during and after closure.
9. INVESTIGATION FOR CLOSEDOWN ACTIVITIES IN THE URANIUM MINE ZIROVSKI VRH
F. CADEZ, B. LIKAR, Z. LOGAR
Abstract: The uranium mine Zirovski vrh was temporarily shut down by order of Government of the Republic of Slovenia in the second half of the year 1990. After the Slovenian parliament passed the law on definite closing down of the uranium mine exploitation and on rehabilitation the effect of mining on the environment in July 1992 was starting to make the Programme of the Permanent Closing down of the Uranium ore Exploitation and Permanent Protection of the Environment in Uranium Mine that is in final phase. In the meantime the studies that would define necessary parameters for elaborating the projects of closure have been done. Two essential studies for the realization of closure of mine are working out: 1. Previous dewatering of the deposit by boreholes for diminishing of pollution of mine water by uranium; 2. Filling of partially collapsed slopes by hydrometallurgical waste to assure permanent stability above the mine spaces. The aim of the first study is to reduce percolation of mine water through the mineralized parts of the deposit by drilling boreholes in the footwall and in the hanging wall. Pollution of mine water which outflows from the lowest tunnel in the local creek Breboväcica should be diminished. Tests of stability and lixiviation on the cubes that are made of hydrometallurgical waste are the topic of the second study. Cement and different additives are added in the cubes and testings have been made in situ.
10. THE DEVELOPMENT OF A TAILINGS DECOMMISSIONING CONCEPT: A CASE HISTORY, RABBIT LAKE, CANADA
L. ADRIAN, N. HOLL, RUHRMANN G.
Abstract: The Rabbit Lake mine and mill facility is located in northern Saskatchewan, Canada, at the northeastern edge of the Athabasca Basin. The Rabbit Lake orebody was discovered in 1968. From 1975 to 1985, approximately 6.5 million tonnes of tailings were deposited in a valley confined by bedrock ridges and two earth-filled dams. Planning for the decommissioning of the Rabbit Lake tailings management facility started in 1983 when the relocation of the tailings into the mined out Rabbit Lake open pit and alternatively, the in-situ decommissioning were examined. The latter was preferred since it offered a sufficiently low individual dose rate and an insignificant environmental impact. Subsequent to the regulatory approval in 1984 to pursue the in-situ decommissioning, three options were considered: (1) A concave surface with natural cover, surface water management and dam stabilization, (2) a convex surface with natural cover, surface water management and dam stabilization and (3) a minimum reclamation option incorporating surface water management only. The 1986 study concluded that the collective public dose over the 1000-year modelling period was acceptable for all three options. However, the concave option was recommended for the final surface shape because it appeared to offer structural integrity and cost effectiveness. The regulatory agencies responded favourably but requested in 1986 that a final surface configuration be adopted only after initiation of tailings dewatering measures and additional field studies. By 1988, an electromagnetic conductivity survey, a pathway analysis, a stream flow reconnaissance and continued environmental monitoring in the vicinity of the tailings area were completed. Subsequent recommendations included the hydrogeological modelling of the area, the hydrogeological evaluation of a cover, the installation of additional piezometers, further geotechnical drilling of the tailings, a radiometric survey, surficial sampling, thermal and consolidation modelling, update of the pathway analysis and a rerun of the electromagnetic survey. These activities were completed by 1991. On the basis of the results, the cover design was optimized taking into account areas of higher consolidation defined by the presence of distal slimes and frozen layers. In addition, pre-loading of the slime area was considered to alleviate post-construction settlements.
11. DECOMMMISSIONING OF URANIUM MILL FACILITIES
C. FEREZ ESTEVEZ
Abstract: The milling of radioactive ores results in contaminated buildings and facilities which must be decommissioned, and large quantities of tailings which must be managed safely so that residual environmental and health risks do not exceed acceptable levels. In the south of Spain on the outskirts of the town of Ândûjar an inactive uranium mill facility is under decommissioning. Mill equipment, buildings and process facilities have been dismantled and demolished and the resulting metal wastes and debris have been placed in the pile. The tailing mass is being reshaped by flattening the sideslopes and a cover system will be placed over the pile. This paper describes the safety aspects and technical approaches which are being used for the remediation and closure of the Andûjar mill site.
12. INSTITUTIONAL AND SOCIAL PARTICIPATION BY THE CITY OF ANDUJAR IN THE DECOMMISSIONING AND DISMANTLING OF THE ANDUJAR URANIUM MILL
J.A. ARCOS MOYA
Abstract: The present paper describes a socioeconomic problem faced by the city of Andüjar. This urban centre is located in the province of Jaén in southern Spain with a population of about 40 000. The Andüjar uranium mill (AUM) which started in 1959 was the source of employment for the city's population. Through the twenty years of operation, there was no problem of social acceptance. After closure of the facility hi 1981, there was a growing awareness among the public on matters related to radiological protection, management of mill tailings and environmental protection. The plan to decommission and rehabilitate the closed mill, which started in 1991, was the source of political debates and sensational journalistic reports that alarmed the population. A commission of the public was eventually formed to study, analyse and discuss its opinions with the government agency (ENRESA) which is charged with the decommissioning programme. These initiatives have allowed the public to develop a better understanding of the project. It is to be emphasized, therefore, that such an activity (decommissioning and rehabilitation) should go hand in hand with informative and socioeconomic measures explaining exactly the environmental situation of the sites.
13. MILLING SITES REMEDIATION - ELEMENTS FOR A METHODOLOGY AS DEVELOPED IN FRANCE BY COGEMA
J.L. DAROUSSIN, J.P. PFIFFELMANN
Abstract: Compared to other metals, mining and milling of uranium generate specific potential hazards due to radioactivity. Remediation of the sites concerned and specially impoundments of mill tailings is a very important step of mining. We first remind the principles and objectives governing site remediation in France. Important steps of the methodology are reviewed: inventory (characterization of the waste products, location and tonnages), some studies which support the choice made for remediation techniques (mineralogical studies, leaching tests, hydrogeological, compaction, stability studies ...) and communication. Some of the cost estimated are mentioned: impact on the environment but also occupational exposure and of course financial costs of the operations. Since 1946 COGEMA has been prospecting, extracting and treating uranium ore first in France and then all over the world. Usually sites have been regularly remediated following closure. Due to general reduction of the uranium mining in France, remediation of the main impoundments has become a major concern in term of long term efficiency and financial costs. Consequently it is necessary to be aware of the different factors and to evaluate or measure the long term impact of each choice.
14. IMPACT OF URANIUM MINING AND PROCESSING IN NORTH BOHEMIA ON CONTAMINATION OF THE PLOUCNICE RIVER BASIN BY RADIOACTIVE MATTER
E. HANSLÎK
Abstract: The River Ploudnice has been loaded with the uranium ore mining and processing wastes water since 1966. Waste water exhibited an increased radium-226 and uranium concentration in dissolved as well as suspended matter. The modern waste water treatment plant has been operated since 1989. The results of the detailed field study on contamination of the river water, interstitial water, bottom sediment, flood area with radioactive matter provided in 1986-1992 are presented. The transport rates of radium in dissolved and suspended matter has been studied under the conditions of artificial flood using water accumulated in the Horka dam. Contamination of the soils with radionuclides in flood area, using the dose rate was measured.
15. UTILIZATION OF AVAILABLE EXPERIMENTAL DATA FOR POLLUTANT TRANSPORT EQUATION COEFFICIENTS AND SOURCE TERM CORRECTION
V. LELEK, M. HRON
Abstract: Physical equations describe always a certain circle of processes the validity of which should be verified by a subset of validity and the sense of their applicability lies in a capability to forecast and predict situations which we do not know at all or know partially and approximately only and therefore we want to have a more precise description at our disposal. For example, the equations describing transport of pollutants in an unsaturated water zone depend on a knowledge of a series of data which have their origin in a set of physical and/or chemical branches. The common current procedure represents a comparison of calculational results with those of measurements and, in case significant discrepancies are detected and the disagreement is not accepted, a revision of the theory is necessary and the whole time and effort consuming process (starting from basic soil parameters and chemical processes involved in the pollution mechanism and its sources up to the solution of time dependent equations) has to be repeated. In addition, the question of which part of the calculational procedure has a maximum share in the discrepancy used to be a very difficult one and not unique to be simply answered. There is an alternative procedure described in the paper which is based on a direct incorporation and experimental results into the basic equation and so the correction of its coefficients. This new model, where the experiments are not only used for its verification or contradiction but also for a broadening of information base of its creation as well as more accurate data on chemical reactions, soil properties and mutual interactions of the processes involved, is mathematically described as a minimization of a functional formed by a sum of the squares of differences between computational and experimental values divided by the values of measuring errors with a side condition of a fulfilling of a set of partial differential equations forming (according to the nature of the task) either an eigenvalue or a non-linear and time-dependent problem. There is a principal mathematical algorithm allowing an optimal elaboration of all the data involved in the process (streaming of unsaturated water with pollutants generated in the process of uranium mining in the subsurface layers of the earth crust and during the uranium mine and mill closure) with a condition of the most precise prediction of the future situation presented in the paper.
Planning and management of uranium mine and mill closures