Hydrogeological conditions are crucial for the site selection and long-term safety assessment of high-level radioactive waste (HLW) disposal repositories. This study focuses on the groundwater circulation characteristics of Xinchang preselected site and its southern periphery of the Beishan area for HLW disposal. A comprehensive approach employing multiple environmental isotopes, hydrodynamics, and numerical modelling was used to investigate groundwater circulation within the study area. Results indicated that groundwater in shallow loose sediments exhibited relatively rapid renewal rates, with an average age generally less than 30 years. The apparent ¹⁴C age of deep bedrock groundwater generally exceeding 10 ka within the underground research laboratory (URL) site. There was no evidence of contributions from deep crustal or mantle sources to groundwater within the region. Within the Xinchang site, the groundwater head shows pronounced vertical stratification, with a higher hydraulic head in shallow zones than in deeper ones. Groundwater in boreholes distant from the gully shows weak hydraulic connectivity with precipitation, and the groundwater level often exhibits periodic fluctuations. The groundwater flow systems can be categorized into three types: regional, intermediate, and local. The local flow system was the most active, accounting for over 80 % of the total flux. These characteristics showed that the hydrogeological conditions in the study area were favorable for the geological disposal of HLW.

With the rapid development of sandstone-type uranium exploration in China, the workload of production logging has been increasing year by year. Simultaneously, with breakthroughs in the exploration of the “second prospecting space”，the logging depth is gradually increasing to 1 000 meters. The existing logging equipment requires 2-3 downhole operations to complete uranium geophysical logging，resulting in long logging times and risks such as borehole collapse and pipe sticking. By developing a modular multi-parameter downhole sub，we have addressed the issues of mutual constraints and interference among electrical，acoustic，and radioactive parameters in logging applications. This has led to the creation of a flexible downhole probe that can be combined according to actual application needs. We have also developed an integrated ground control platform and accompanying logging data acquisition and processing software, forming a highly integrated, noise-resistant, and fast-responding digital control system. This has culminated in the development of the new-generation NDL461 digital integrated logging tool. This logging tool has passed third-party verification and has been field-tested in the Songliao，Qaidam，Yili，and Tarim basins，demonstrating its stability，accuracy，and applicability. The developed logging tool provides technical equipment support for China’s fourth-generation uranium exploration technology system.

In order to reveal the complete geological structure of Xiangshan volcanic basin and explore the metallogenic prospect and potential in the central part of the basin, the Xiangshan Uranium Field Deep Scientific Exploration phase II project deployed a 3 000 meter deep scientific borehole, named CUSD2-1, at “Xingshuxia” in the central part of the basin. To insure the smooth conduction of the drilling, we adopted the advanced AC frequency conversion electric top drive geological core drill, large diameter wireline core drilling technology, anti-inclination and control wireline core drilling tools, high efficiency diamond bit and efficient drag reducing lubricating drilling fluid, which successfully solved the technical problems of deep drilling in complex formation, such as low drilling speed in hard rock, stable hole wall in broken formation, hole leakage, anti-inclination and control in strongly deflecting formation, and safe drilling with large diameter wireline coring, and finally drilled to the predetermined depth, creating the deepest record of S (φ150 mm) diameter wireline coring in geological core drilling in China, and revealed the deep formation structure. This deep drilling provides valuable geological data for deep uranium resource exploration in Xiangshan, which not only has special significance for the scientific research and exploration of deep uranium resources, but also has great significance for the improvement of engineering technology for deep-ultra deep geological drilling.