With the rapid development of nuclear energy in China, challenges with respect to the safe disposal of high-level radioactive waste (HLW) are increasing. China’s strategy for HLW disposal is divided into three phases: (1) laboratory-based research and site selection for the disposal facility (2006-2020), (2) underground research and testing (2021-2040), and (3) the disposal facility construction (2041-2050). The 13th Five-year Plan for the National Economy and Social Development of China (2016-2020) determined that “the construction of China’s underground research laboratory (URL) for HLW disposal should start before 2020”.Site selection for China’s deep geological repository (DGR) started in 1985. In 2011, the Beishan area of north-western China was recommended as the top priority area for China’s DGR. This decision provided an important basis for selecting the URL site. Based on the achievements obtained from site selection of the DGR, site selection for China’s URL started in 2015. Altogether 9 candidate URL sites were selected for further comparison. According to the strategy to build an area-specific URL in combination with the site characterization results, a systematic comparison was conducted among the 9 sites. The result was that the Xinchang site in the Beishan area was determined as China’s URL site. Hence, we call China’s first URL for HLW disposal as the Beishan URL. The rock masse at the Beishan URL site has very good integrity and extremely low permeability. In addition, high strength and low in-situ stress level of the rock masse is favourable for the excavation stability.
On May 6, 2019, the China Atomic Energy Authority (CAEA) approved the “Beishan URL Construction” project. The construction period of the Beishan URL is from 2021 to 2027. A significant milestone is that, on June 17, 2021, China kicked off the construction of the Beishan URL, and a ground-breaking ceremony was held at the URL site, marking that China’s efforts on HLW disposal has entered a new phase, i.e., the URL development stage.
The Beishan URL is characterized by the layout of three shafts, one spiral ramp, and two experimental levels with a maximum depth of 560 m (Fig.1). The three shafts include one personnel shaft and two ventilation shafts. The drill-and-blast method will be used for excavation of the 6-m-diameter personnel shaft, while raise boring machine will be used for excavation of the two 3-m-diameter ventilation shafts. The spiral ramp has a length of about 7 km, a cross-sectional diameter of 7 m and a maximum curve diameter of about 255 m. The ramp will be excavated using the full-face tunnel boring machine (TBM), with the aim to minimize the damage to surrounding rocks. The ramp of the Beishan URL is currently the world’s first spiral ramp planned to be excavated by the TBM. The experimental tunnels will be planned to be constructed at two levels, i.e., -280 m and -560 m levels.
The excavation of the personnel shaft and the ramp of the Beishan URL started in April 2022. A comprehensive field-testing programme focusing on site characterization, technology development and testing will be performed during URL construction, including geological mapping, geophysical surveying hydrogeological investigations, rock suitability evaluation, TBM penetration test, in-situ stress measurements and excavation damage zone (EDZ) characterization, etc.
On October 17, 2021, the International Atomic Energy Agency (IAEA) designated the Beijing Research Institute of Uranium Geology (BRIUG) as the IAEA Collaborating Centre for Geological Disposal of High-level Radioactive Waste. The BRIUG will support the IAEA in the implementation of activities in the IAEA Programme “Nuclear Power, Fuel Cycle and Nuclear Science”, with the aim to enhance IAEA Member States capabilities in geological disposal of HLW. The Beishan URL will provide a platform for IAEA Member States to exchange practical experiences relevant to the planning and construction of a new URL. Meanwhile, this facility will be open for international cooperation in related scientific and technological fields.
Currently, the ramp entrance is being excavated by drill-and-blast method to provide space for assembly and trial operation of the TBM. The excavated length of the ramp reaches 392 meters on 1 September 2022. Geological mapping is being conducted following the tunnelling process. It is expected that the achievements to be gained from the Beishan URL will successfully contribute to the development of China’s DGR and similar facilities worldwide.
Fig. 1. A 3D perspective view of the Beishan URL.