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The area of the town of Mailuu Suu, Kyrgyzstan, is polluted by radionuclides and heavy metals in tailing dumps and heaps resulting from the historic exploitation of U-mines in the Mailuu Suu area in Kyrgyzstan. Radioactive substances are stored in 23 tailings and 13 mining debris heaps situated along the Mailuu Suu River. The objective of the EC-TACIS funded project is to evaluate and prepare measures to be taken by the authorities to reduce the radiological exposure of the population and to prevent environmental pollution by radionuclides and heavy metals in case of loss of tightness of dams and damage to dumps and heaps from mining and milling by land and mudslides and to propose sustainable remedial options, accepted by the public. The actual radiological situation is of no immediate concern for most of the population of Mailuu Suu. From the gamma radiation monitoring campaign (monitoring network in Mailuu Suu, Kara Agach and vicinity), it showed that the background radiation is 100–120 nSv/h. On the tailings radiation is on average twice background. The average outside and in-house radon concentration is 175 Bq/m3. In 3 of the houses monitored at Kara Agach the radon level is between the exemption limit for new (200 Bq/m3) and old (400 Bq/m3) houses. The concentration of uranium in the Mailuu Suu river water is far below the exemption limit for drinking water set in Kyrgyzstan. Additional dose from irrigation with Mailuu Suu river water is small in actual conditions (< 0.1 mSv/year). However, there is an important possibility that triggered by an eathquake or a landslide, (part of the) tailing(s) content may be directed to the river Mailuu Suu. Doses to the affected population may increase to multiple ten mSv per annum. Given the actual limited stability of Tailing N°3, the potental of such a disaster to occur isnon-neglegible. To impede the consequences of a potential disaster, under the TACIS project different remedial options are evaluated for Tailing 3 including in situ stabilisation and tailing translocation. Also more global remedial options for the Mailuu Suu River valley are studied (translocation of other tailings, tunnel to deviate river, partial protection of river from landslide blockage). It was proposed to acquire a phased approach in time performing urgent limited stabilisation options for Tailing 3, improve the stability of the Tailing 3 by COLMIX-columns in the medium term, while investigating and evaluating further two long-term remedial options: the translocation of the tailings and the long-right-bank river diversion tunnel.

The economic feasibility of short rotation coppice (SRC) production and energy conversion in areas contaminated by Chernobyl-derived (137)Cs was evaluated taking the spatial variability of environmental conditions into account. Two sequential GIS-embedded submodels were developed for a spatial assessment, which allow for spatial variation in soil contamination, soil type, and land use. These models were applied for four SRC production and four energy conversion scenarios for the entire contaminated area of Ukraine, Belarus, and Russia and for a part of the Bragin district, Belarus. It was concluded that in general medium-scale SRC production using local machines is most profitable. The areas near Chernobyl are not suitable for SRC production since the contamination levels in SRC wood exceed the intervention limit. Large scale SRC production is not profitable in areas where dry and sandy soils predominate. If the soil contamination does not exceed the intervention limit and sufficient SRC wood is available, all energy conversion scenarios are profitable.

Permeable reactive barriers (PRBs) are increasingly being used as a cost-effective technique for in-situ treatment of contaminated groundwater. This paper discusses the results from batch tests with six different reactive materials, including zero-valent iron (ZVI), ferric oxyhydroxides, and some composite materials. All materials were tested in their ability to remove uranium and arsenic from groundwater. Results show that fine-grained ZVI was most successful in removing uranium from solution, up to a removal efficiency of 98%. The main mechanism in removing uranium presumably is by reductive precipitation. The results further showed that arsenic removal is most efficient with ferric oxyhydroxides (maximum removal efficiency is 96%). This study illustrates that PRBs using a mixture of fine-grained ZVI and materials containing ferric oxyhydroxides as reactive material may help significantly in removing uranium and arsenic from groundwater.

In-situ treatment of contaminated groundwater by means of permeable reactive barriers (PRBs) is becoming a cost-effective remediation technique. Various reactive materials that might be used in PRBs were tested in their ability to remove uranium from groundwater. Materials tested include ferric oxyhydroxides, coarse- and fine-grained zero-valent iron, aluminium-iron oxides, and zeolites. Batch tests were used to evaluate the removal efficiency of these materials. To analyse the effect of groundwater composition on the interaction between dissolved uranium and reactive materials, two types of groundwater were used, mainly differing in carbonate content and pH. Considering an equilibration time of 48 hours and initial uranium concentrations between 2.4 and 24 mg/1, finegrained zero-valent iron proved to be most effective with a uranium removal efficiency of more than 96% for carbon-rich groundwater and 99% for carbon-poor groundwater. Intermediate efficiency was observed for coarsegrained zero-valent iron and aluminium-iron oxides. Less than 10% of the dissolved uranium was adsorbed on the iron oxyhydroxides. Zeolites did not remove any uranium from solution. Results further indicated a positive correlation between dissolved inorganic carbon content and dissolved uranium at equilibrium. Because it can be easily obtained at a fairly low price, zero-valent iron is a promising material for use in PRBs.

Following the Chernobyl accident, many thousands of square kilometres were severely contaminated in the CIS and the application of corrective measures in contaminated areas remains a key issue in large territories of Ukraine, Belarus and Russia. When agricultural perspectives must be abandoned in these territories because of high levels in food products or because of economically or technically non-realistic corrective options, an increasing interest arises in developing more integrated and ecologically based approaches. In this context, industrial crops, not used for food production, may be an alternative remediation option.

Countermeasures in agriculture aim mainly at preventing the production of foodstuffs with unacceptable concentration levels of pollutants, which would therefore be unfit for human consumption or animal feeding. The Chernobyl accident severely contaminated the environment. The scale and heterogeneity of the territory affected, especially in the CIS, makes difficult any implementation of a priorization in remediation strategy. When large areas with moderate contamination levels, although too high for unrestricted use, are considered, an interest thus exists in developping soft ecologically-based countermeasures to limit the radionuclides’ availability in soils: among others, limiting the soil to plant transfer by increasing the competition for root uptake between the pollutant and plant nutrients (fertilisers) or by decreasing the pollutant solubility in the soil, and hence its bioavailability for plant uptake, by the addition of specific binders like clay minerals or chemical products can be envisaged.

In the past, the decision to apply countermeasures following nuclear accidents has been based primarily on their effectiveness in averting dose to man. However, particularly in recent years since the Chernobyl accident in 1986, it has been realised that other factors also need to be considered. These include the reasons and justification for introducing the countermeasure, the time scale over which they will be used, their effectiveness and their practicability. Practicability includes factors such as technical limitations and capacity, exposure during implementation, potential environmental impacts, economic implications and acceptability (both social and ethical) as well as a number of site specific issues. These criteria have been used to evaluate a range of commonly used countermeasures and a spreadsheet information system has been prepared by the members of an IUR Action Group. The system highlights factors to be taken into consideration in making a decision on the implementation of countermeasures.

Bean seedlings were grown under controlled conditions on a Hoagland solution. Ten-day-old seedlings were exposed to 0, 0.1, 1, 10, 100 and 1000 µM U or 0.5 and 1 µM Cd. Following 7 days’ exposure, plants were sampled for determination of contaminant uptake, biometric parameters (shoot and root length, area of primary leaves, weight of shoot, root and primary leaves) and activity of enzymes involved in the plant’s anti-oxidative defense mechanisms. Generally we did not observe a significant difference in plant development between control and treated plants based on biometric parameters. Enzyme activities in roots were stimulated with increasing contaminant concentrations (though generally not significantly). However, for roots exposed to 1000 µM U, enzyme activity was generally significantly reduced. In shoots no significant difference in the defense mechanism between the treatments was observed.