| Deep geological disposal is the most suitable and effective scheme for long-term storage of long-life high-level radioactive waste.Clay rock has became one of the important surrounding rock types for the siting of disposal repository,because of the favorable barrier and adsorption effect on radionuclides,which can effectively reduce the migration of nuclides.Meanwhile,it has the advantages of self-sealing,low permeability.Inner Mongolia Tamusu area is one of the important research areas of the clay rock site for the high-level radioactive waste clay rock disposal repository in China,with the developing of the screening of geological disposal sites for clay rock high-level radioactive waste.In this paper,based on the analysis and summary of the previous geological and geophysical knowledge in the Tamusu area,we have comprehensively used various geophysical data,and taken three-dimensional geological modeling technology.Finally,the geophysical exploration technology for the site selection of high-level radioactive waste clay rock disposal repository from the "pre-selected area" to the "pre-selected section" to the "preferred location" in the Tamusu area are proposed,combined with the site selection standards of clay rock repository.Three-dimensional geological modeling research was constructed which was based on the gravity,magnetic,12 reflection seismic profiles,topographic and borehole data in the pre-selected area.According to the analysis of geological model,the pre-selected section of high-level radioactive waste clay rock disposal repository are delineated.In the pre-selected section,we arranged four magnetotelluric sounding(MT)profiles,and interpreted the characteristic of electrical distribution and existence of deep strata through inversion results,further delineated the preferred location for high-level radioactive waste clay rock disposal repository.In the preferred location,controlled source audio-frequency magnetotelluric sounding(CSAMT)exploration work was carried out,and spacial extension scale and continuity of clay rock in the preferred location were delineated.Furthermore,the mudstone thickness and buried depth of Bayingobi group target formation in the lower layer was obtained.Basing on the inversion results of CSAMT,three-dimensional geological modeling of preferred location was completed.Combined with three dimensional geological modeling and the geophysical exploration technology of high-level radioactive waste clay rock disposal repository site at the multiscale,the lower layer of Bayingobi group was determined as the target layer of the preferred location of the clay rock disposal respository in Tamusu area,which has continuity and overall layer thickness greater than 100 m,within 400 ~ 800 m average depth.The overlying strata in the upper layer of the Bayingobi is stable,with gentle terrains and simple lithological,without fracture.Therefore,it satisfied the site selection standards of clay rock repository,and,can take further investigation in the preferred location. |
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