China
Africa
Explore chapters and articles related to this topic
Practical Issues in Disposal of High-Level Radioactive Waste in Crystalline Rock
Published in Roland Pusch, Raymond N. Yong, Masashi Nakano, Geologic Disposal of High-Level Radioactive Waste, 2018
Roland Pusch, Raymond N. Yong, Masashi Nakano
Instead of real copper/iron KBS-3 canisters, 0.76 m diameter Teflon-coated aluminum model canisters equipped with 600–1,500 kW heaters were used for simulating the conditions in a full-scale MR repository of KBS-3V type. The buffer clay, the performance of which was in focus in the approximately 3-year-long field test, was montmorillonite-rich clay (MX-80) with a net dry density of about 1,850 kg/m3. The backfill in the 12 m long and almost 6 m high drift, which had the same cross section as full-scale KBS-3V deposition tunnels, consisted of mixtures of 10% clay and 90% silty/sandy soil from the floor up to about 2.5 m height, and of mixtures of 20% clay and 80% silty/sandy soil in the upper part. The higher clay content in the uppermost backfill was for compensating the poor expandability of the lower part. The lower part was placed in 10–15 cm layers and compacted by use of vibratory plates, while the upper part was backfilled by shotcreting. The achieved density of the latter was found to be too low and to give too large compression by the dense smectite-rich buffer clay in the canister deposition holes beneath (Figure 4.20).
The problem of radioactive wastes
Published in Matthew Cotton, Nuclear Waste Politics, 2017
Following this process of voluntarism, in 2009, SKB selected a site and applied for permission to build a repository for spent nuclear fuel near to Forsmark (the home of an existing nuclear reactor) and an encapsulation plant in Oskarshamn – thus creating the final disposal solution for the spent fuel from Swedish nuclear power plants. To get to that point, SKB had to choose between Forsmark in the municipality of Östhammar, and Laxemar in the municipality of Öskarshamn. When it chose Forsmark, it then sent in (in 2010) applications for permits to the Swedish Radiation Safety Authority and the Environmental Court, complete with environmental impact assessment (EIA) and a safety analysis for a spent fuel repository. In theory, this will be the first permanent disposal solution for high-level waste to be built in the world, yet it has recently come under fire from independent scientific scrutiny. The KBS-3 model, using copper canisters, has been shown under experimental conditions to be more susceptible to corrosion than was first thought. Corrosion was shown to be accelerated by heat and radiation emitted by radioactive waste, casting doubts over copper’s suitability as a material for disposal. There was also concerned about the erosion of the bentonite clay over time. Moreover, in 2016 the Swedish National Council for nuclear waste, Kärnavfallsrådet, published a report which identified a range of project risks and uncertainties related to seismic impacts, issues of finance and the monitoring of the site’s condition over the long-term (Kärnavfallsrådet, 2016). All-in-all the council’s report as an independent scientific evaluation, has played an important role in revealingly KBS-3 project’s flaws; leaving the future of the project in jeopardy.
Thermal Conductivity Estimation of Compacted Bentonite Buffer Materials for a High-Level Radioactive Waste Repository
Published in Nuclear Technology, 2018
Seok Yoon, Min-Jun Kim, Seung-Rae Lee, Geon-Young Kim
The usage of nuclear energy that comprises 30% of the total electricity generation in Korea is growing steadily. At present, there are 25 nuclear reactors in operation domestically signifying that nuclear energy is highly recognized as an important energy source in Korea. However, spent fuel produced from fuel usage in nuclear power plants comprises highly radioactive forms of waste and poses dangerous health risks to humans upon exposure to the radiation and heat emitted from the spent fuel. For these reasons, the issue of high-level radioactive waste (HLW) disposal has been consistently raised. In response to such concerns, the Korea Atomic Energy Research Institute (KAERI) has continued to conduct research on the topic of deep geological disposal of spent fuel since 1997 and has proposed a disposal system based on the Sweden KBS-3 disposal concept, taking into consideration the deep underground environment of Korea.1–3
EUROCORR 2017 in combination with the 20th International Corrosion Congress and the Process Safety Congress 2017: corrosion control for safer living, part 4
Published in Corrosion Engineering, Science and Technology, 2018
‘Copper behaviour in geological nuclear waste disposal’ was discussed by H. Hänninen (Aalto University School of Engineering, Espoo, Finland). The KBS-3 method, initiated in Sweden, uses a specially designed copper container to provide a relatively thick corrosion barrier of 50 mm of copper. The main degradation mechanism of copper was likely to be associated with sulphide present in groundwater, produced by the microbiological activity. In compacted bentonite clay, the general corrosion rate was expected to be dominated by the slow transport of the sulphide ion. Radiation-induced corrosion, localised corrosion, SCC and hydrogen-induced cracking were also considered. Additionally, creep ductility of copper was examined. Originally, it was intended to use pure oxygen-free Cu–OF (without phosphorous) for the canisters. The choice at present is oxygen-free copper with phosphorus alloying (Cu–OFP, between 30 and 100 ppm P).
Visualization of Mass Transfer Between Source and Seeping Water in a Variable Aperture Fracture—Impact of Tracer Density
Published in Nuclear Technology, 2020
Helen Winberg-Wang, Ivars Neretnieks
The Swedish method of disposal of high-level nuclear waste, called KBS-3, utilizes three barriers. The waste is encapsulated in copper canisters and placed in holes in the bedrock at a depth of about 500 m. The canisters are embedded in compacted bentonite clay. The third barrier is the rock itself. The equivalent flow rate Qeq, quantitatively describes the transport capacity of solutes, including radionuclides, to seeping groundwater in the rock. It is used to quantify the release rate of radionuclides from a leaking copper canister. It can also be used to assess the rate of transfer of corrosive agents from the groundwater to the canister.