| Geological disposal was considered the most favourable methods for high-level radioactive waste disposal. It was adopted by IAEA and by developed nations with nuclear facilities. However, how to choose the host rock of the repository for high-level radioactive waste geological disposal become more essential. Many countries have conducted extensive studies on host rocks of the geological repository and found that granite, argillaceous rocks, salt and tuff are suitable as the host rocks for the geological repository. Chinese HLW disposal efforts in the past decades were mainly focused on granite formation. Moreover, comparison with granite, argillaceous formation is considered to have many advantages due to its self sealing ability and low permeability, more and more attention has been paid to the studies of argillaceous formation as the host rock of geological repository for HLW in the world.This article focuses on the research of geological conditions, the basic physical properties and permeability of the clay rock in Nanbaxian condidate region of Northwest Qaidam Basin. The results show that:(1)Nanbaxian condidate region is located in Mahai-Dahonggou uplift,Northwest Qaidam basin, which new tectonic movement and activestructure is undeveloped,tectonic conditions.tectonic conditions and theearth’scrust is stable.(2)Geological prospecting has been conducted on the clay formation in Nanbaxian Condidate Region, Qinghai Autonomous Region, which suggested that the clay formation in Nanbaxian condidate region were formed in a stable sedimentary environment with widely extending horizontal stratum.Rockstratum approximately sloped to south west direction with low-angle of 6°.Clay rock belongs to Shore shallow lake deposits.On the lower part of Youshashan group.(3)The Clay rock is given priority to with Gray green and Purple red mudstone,with high argillaceous components in Nanbaxian condidate region.Furtherstudies on petrology and mineral characteristics by X-ray diffraction indicated that the clays are mainly composed of kaolinite and illite with the politic texture and compact structure. Rock good adsorption performance can effectively block the radionuclide migration.(4)The source rocks of the clayrock in Nanbaxian condidate region is mainly Granitic gneiss in Qilian orogenic belt.Sedimentary environment is the reductive environment.Clay rock inherited tectonic environment of source rock geochemistry related information.Referring to the requirements and standards of site selection in foreign developed countries, the preliminary results of this study showed that the clay formation is basically meet the requirements as the host rocks for HLW geological disposal. |
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