Study On Application Of The Integrated Geophysical Exploration To Potential High Level Radioactive Waste Geological Disposal Sites

Nowadays, it is necessary and urgent to have the geological high level radioactive waste disposal (GHLRWD), one of 100 key projects of China's 13th five-year plan. Now,China's HLRWD is still at the critical stage of selecting sites. Based on an analysis of the critical geological issues at the select:ing stage, there are two core issues for the geophysical exploration: detecting the fracture zones in the rock body and delineating the suitable area of the rock body to deposit the waste. The former is solved by improvement of the reliability of inverting AMT data using AMT and seismic joint surveying methods.The latter is finished by joint surveying of MT and the ground magnetic measuring. The paper gives the geophysical detecting steps meeting the demand of HLRWD at the selecting site stage in the arid uncovered granite rock body. The paper covers three study aspects as following:(1) The high quality natural electrical and magnetic signals are acquired by mending field measuring steps. An AMT data inversion route is presented by comparing with anomaly reliability using adjusted model's dimension and scale. Based on the following steps, the effective of detecting the buried structure in the bared granite setting of the arid environment by AMT or MT is improved. The EM detecting reliability over setting is also increased.(2) In order to meet the low SN ration of seismic surveying on the uncovered granite rock, the scattering imaging method is used to improve the imaging quality. The EM and seismic jointing detection of the buried fracture zone is raised and detecting detailed buried fracture zones is achieved.(3) It s a speedy exploration to delineate suitable area of the rock body with single EM profile and ground magnetic surveying. 3-D EM inversion combined with larger scale area magnetic surveying is preliminarily studied for this purpose.Based on the study of these aspects focusing on the two core problems above,a clear geophysical exploration route for our country 's special environment at the selecting site stage of GHLRWD is presented including three steps with corresponding object and arrangement. Above all, with exploitation cases,it is hoped that all these techniques can provide certain reference values for selecting the potential sites of HLW of our country.