Abstract

With the rapid development of nuclear power in China, the disposal of high-level radioactive waste (HLW) has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories (URLs) play an important role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China's URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area, located in Gansu Province of northwestern China, has been determined as the final site for China's first URL in granite. In the process of characterizing the Xinchang URL site, a series of investigations, including borehole drilling, geological mapping, geophysical surveying, hydraulic testing and in-situ stress measurements, have been conducted. The investigation results indicate that the geological, hydrogeological and engineering geological conditions of the Xinchang site are very suitable for URL construction. According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed.

1.
Introduction

Safe disposal of high-level radioactive waste (HLW) is a challenging task for the sustainable development of nuclear energy and environmental protection. Geological disposal is considered as a feasible and safe option for the long-term management of HLW worldwide, and many countries have considered building deep geological repositories (DGRs) in which to dispose of spent fuel or vitrified HLW. In order to investigate the suitability of geological rock formations for hosting DGRs, to develop and test disposal concepts and technologies, to gain knowledge about multi-field coupled processes in geological and engineered barriers, and finally to assess and demonstrate the long-term performance and safety of DGRs, a number of underground research laboratories (URLs) have been constructed around the world (Kickmaier and McKinley, 1997; NEA, 2001; Wang, 2007).

URLs can generally be divided into generic URLs and site-specific URLs. Generic URLs are facilities developed for research and testing purposes at a site that will not be used for waste disposal while site-specific URLs are facilities developed as a potential site for waste disposal and a precursor to the development of a repository at the site (NEA, 2001; Ahn and Apted, 2010). In the past few decades, generic URLs have been developed within pre-existing underground excavations, such as mines and tunnels; e.g., the Grimsel Test Site and Mont Terri road tunnel in Switzerland and the Tournemire facility in France. There are also purpose-built generic URLs in specific rock types, such as the Äspӧ Hard Rock Laboratory in granite in Sweden and the Whiteshell URL in granite in Canada. The site-specific URL may be constructed either adjacent to or within the proposed repository location. Site-specific URLs include the ONKALO URL in granite in Finland, the Meuse/Haute Marne URL in claystone in France (Delay et al., 2010), the Gorleben URL in salt in Germany, and the ESF in volcanic tuff in the United States (NEA, 2001).

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