Research On The Roadway-scale Suitability Evaluation Method (Q_HLW) Of High-level Radioactive Waste Repository

The suitability evaluation of host rock plays an important role in the development of high-level radioactive waste?HLW?disposal repository.The conventional methods,such as Q,BQ,and RMR,are unsuitable for the HLW disposal project because of the long-term requirements.Dr.Chen?2015?and Dr.Zong?2013?proposed a specific method Q_HLW for evaluating the suitability for the HLW disposal and this method was suceessfully used in the selection of China's underground research laboratory site?URL?.China is now preparing for the construction of the URL and thereby it is necessary to update this method from the site-scale to tunnel-scale.In this paper,some efforts were made on updating the frame work,evaluation indexes and criteria of Q_HLW method according to the requirements.In this paper,the Rock Suitability Classification?RSC?system proposed by Finland was firstly introduced,especially its“avoidance criterion”.Taking account of the disposal concept and rock type?similar with Finland?in China,the RSC system of was then applied to evaluating the geochemical,geo-hydrological and mechanical suitability of Xinchang Site,which is the site of China's URL.The evaluation results were composed to that of Q_HLW system and the framework of Q_HLW system was updated.The evaluation indexes of Q_HLW system were then studied and the groundwater chemical index was improved.Based on the research achievement of the canister and bentonite erosion,the new sub-indexes,Canister Erosion Index and Buffer Erosion Index,were add into the groundwater chemical index and the evaluation criteria were updated according to the specific material used for disposal canister.The extenics method,a calculating procedure from the concept“matter-element theory”,was imported into the Q_HLW system in order to obtain more reliable and more inferable evaluation results.On the basis of single factor classification,the multi-factors contradiction was quantitatively analyzed and the evaluation results were obtained by considering the weights of all the factors and the objects we investagated were in the same scale.This method was tested and verified by carrying out the rock mass evaluation based on the data from BS03 borehole at Beishan site and its single-factor classification and the weight of muti-factors calculation were optimized.Then this method was appied to carrying out the preliminary rock suitability evaluation of Q_HLW at the tunnel scale by using the information from BS28,BS32 and BS33 borholes.The results verified the suitability of the rock mass in the depth 400-600m of Xinchang site.