Two-layer soil covers on selected radioactive waste rock dumps at Wismut: results of more than ten years of hydrological monitoring

ABSTRACTThe Chinese government has conducted remedial action for radioactive waste rock piles since 1990. The radioactive waste rocks produced in the course of geological exploration of uranium deposits are widely distributed over several hundreds of locations in more than 20 provinces in China.The following remedial actions for radioactive waste rock piles have been undertaken in China:1. Protecting dams for stabilizing the piles have been built. A total length of about 50,000 m of these dams has been completed.2. Soil layers have been emplaced on the radioactive waste rock piles. The focus of the action is to eliminate the radiation harmful to public health. A total area of 750,000 square meters of soil ahs been placed on the piles in China.3. Radioactive waste rock piles have been vegetated. Aesthetic shaping of the landscape in the exploratory district of the uranium deposits is our expectant goal. A total area of about 560,000 square meters of vegetation has been placed on the soil covering the piles.Through these remedial actions, the environmental situation has been extensively improved in the remedial districts. The individual annual effective dose equivalent is less than 1 Sv/a. The radon emission rate is less than 20 pCi/m2.s. The gamma ray external exposure rate has been greatly reduced.

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Improving water storage of reclamation soil covers by fractionation of coarse-textured soil

Canadian Journal of Soil Science ◽

10.4141/cjss2013-086 ◽

2014 ◽

Vol 94 (4) ◽

pp. 489-501

Author(s):

Yekaterina V. Dobrovolskaya ◽

Henry Wai Chau ◽

Bing Chen Si

Keyword(s):

Preferential Flow ◽

Soil Cover ◽

Water Storage ◽

Waste Rock ◽

Wetting Front ◽

Mining Operations ◽

Natural Sand ◽

Soil System ◽

Soil Covers ◽

Number Of Layers

Dobrovolskaya, Y. V., Chau, H. W. and Si, B. C. 2014. Improving water storage of reclamation soil covers by fractionation of coarse-textured soil. Can. J. Soil Sci. 94: 489–501. Mining operations cause considerable land disturbance as well as the accumulation of large amounts of waste rock. Capping waste rock with a soil cover has proven to be a reliable, long-term reclamation technique. This study examines the question of whether it is possible to attain a considerable increase in water storage capacity (WSC) by separating coarse-textured soil into particle size fractions and layering them into a soil cover. Additionally, this study investigated whether preferential flow can be mitigated by increasing the number of layers and extending the interlayer transitions in fine-over-coarse-textured soil systems. Intermittent and constant infiltration experiments were conducted on homogeneous covers composed of natural sand, two-layered covers with abrupt and gradual interlayer transitions as well as on a four-layered cover under initially air-dry and field capacity (FC) conditions. Water storage capacities were determined from a sampling of soil covers’ water content at FC. Infiltration experiments showed that all tested covers under all initial and boundary conditions had limited susceptibility to preferential flow. Increasing the number of layers and extending the interlayer transitions had a stabilizing effect on the wetting front. Water storage capacities and residence time increased with the increased number of layers. Overall, it has been shown that it is possible to improve the WSC of coarse-textured soil by fractionation and layering of it into a relatively fine-over-coarse soil system.

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Scenarios and Pathways of Radionuclide Releases from Near-Surface Waste Disposal Facilities: A Brief Overview of Historical Evidence

Nuclear and Radiation Safety ◽

10.32918/nrs.2020.3(87).03 ◽

2020 ◽

pp. 21-27

Author(s):

D. Bugai ◽

R. Avila

Keyword(s):

Radioactive Waste ◽

Waste Disposal ◽

Safety Assessment ◽

Historical Evidence ◽

Nuclear Facilities ◽

Near Surface ◽

Soil Covers ◽

Low Level ◽

Radionuclide Release ◽

Early Degradation

The very low-level waste (VLLW) produced during decommissioning of nuclear facilities can be suitable for disposal in landfill type facilities. Considering the similarities in design, the experience gained in near-surface disposal of radioactive waste in trenches and vaults is relevant to the issue of VLLW disposal in landfills. This paper presents a brief review of internationally reported cases of radionuclide releases from near-surface disposal facilities. Based on this review, the conclusions are made that the following radionuclide release and exposure scenarios should be accounted for in safety assessment of VLLW disposal in landfills: i) leaching from waste to groundwater by atmospheric precipitations; ii) bath-tubing scenario; iii) scenarios caused by extreme meteorological and hydrological events (erosion, flooding, etc.); iv) human intrusion. The gaseous transport deserves attention for a number of relevant radionuclides, such as (C-14, Rn-222, etc.). In addition, the possibility of early degradation of engineered containment structures (soil covers, bottom seals) should be cautiously considered.

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Final Covering of the Ronneburg Uranium Mining Site

11th International Conference on Environmental Remediation and Radioactive Waste Management, Parts A and B ◽

10.1115/icem2007-7190 ◽

2007 ◽

Author(s):

Uwe Hoepfner

Keyword(s):

Vadose Zone ◽

Monitoring Program ◽

Gas Diffusion ◽

Uranium Mining ◽

Waste Rock ◽

Water Infiltration ◽

Open Pit ◽

Mining Site ◽

Climate Conditions ◽

Soil Covers

The rehabilitation of WISMUT’s former Ronneburg uranium mining site involves backfilling of waste rock to the Lichtenberg open pit. The relocation project comprises about 110 million m3 of sulphide-bearing and AMD-generating waste rock which makes it the most important and most cost-intensive single surface restoration project conducted by WISMUT at the Ronneburg site. The backfilled waste rock has to be covered on an area of about 220 ha to control water infiltration and gas diffusion. Design planning for the final cover placement which began in 2004 had to be based on a comprehensive cost-benefit analysis as well on field tests of alternative cover options which are in compliance with legal requirements. An intensive testing program concerning the vadose zone of soil covers has therefore been started in 2000. The paper presents an overview of the monitoring program and the results of the vadose zone measurements. The water of soil covers have to be predicted for extended evaluation periods. Therefore water balance simulations of single layer covers (storage and evaporation concept) taking current and future soil and climate conditions into account are performed with the HYDRUS_2D code.

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