China has started building a laboratory deep underground in the Gobi Desert to assess whether it would be a suitable location for a nuclear waste dump, amid moves to expand its nuclear power capacit y. The Beishan Underground Research Laboratory in the northwestern province of Gansu will be used to research long-term storage of high-level radioactive waste. With its deepest level to be built 560 metres (1,837 feet) below ground, it will be the world’s largest lab of its kind, according to the China Nuclear Energy Association, which promotes nuclear power. The world has about a quarter of a million tonnes of highly radioactive waste, all kept in “temporary” storage. No country has found a solution for permanent deep geological storage, with public opposition often a factor. China’s attempt to find an answer comes at a time when it plans to build a fleet of new reactors. Disposal of high-level radioactive waste is becoming more critical as it uses more nuclear power and tries to become carbon neutral . The Chinese government aims by 2025 to expand the country’s nuclear capacity by about 40 per cent from its late-2020 level. Nuclear power currently makes up only about 5 per cent of China’s power generation. It is estimated that the lab will cost over 2.7 billion yuan (US$400 million), take seven years to build and operate for 50 years. If research proves the site to be suitable, a long-term underground repository for high-level radioactive waste will be built nearby by 2050, Wang Ju, chief designer of the lab, told state media in April. Nuclear waste can be divided into three categories of radioactivity level. Low-level waste consists of minimally radioactive materials used in nuclear power plants, while intermediate-level contains higher amounts of radioactivity, such as used reactor components. Together they account for about 99 per cent of radioactive waste. China has three disposal sites for low and medium-level waste, in Gansu, the southern province of Guangdong, and Sichuan, in the southwest. It aims to build five further sites in the coming years in coastal provinces with nuclear power plants, such as Zhejiang, Fujian and Shandong, which are not equipped with disposal facilities. High-level waste refers to spent nuclear fuels and the safest known disposal method is to bury such material deep underground indefinitely. The world’s first deep geological repository for spent fuel is under construction in Finland, and is expected to begin operating in 2023. The total estimated cost is 2.6 billion euros (US$3.1 billion), according to the Radiation and Nuclear Safety Authority of Finland. A nuclear energy expert said China’s laboratory was important for its pursuit of a closed fuel cycle. “There are two policies used for nuclear fuel around the world: an open policy and a closed policy,” said David Fishman, manager at energy-focused consulting group The Lantau Group. “The idea of a closed fuel cycle policy is to reprocess the fuel by breaking down the waste, to make it less dangerous and extract valuable things in it – such as inefficient uranium, plutonium and some types of fission products that might be useful for medical or industrial use. China is taking a step in that direction.” China operates a pilot reprocessing plant in Gansu with an annual processing capacity of 200 tonnes of uranium, according to the International Atomic Energy Agency. In 2018, China and France signed an agreement to build a reprocessing and recycling plant at a cost of 10 billion euros. The Chinese government’s five-year plan for 2021 to 2025, released in March, outlined an intention to build more disposal sites for low and medium-level radioactive waste, along with more nuclear fuel reprocessing plants. Fishman said most European countries have a closed fuel cycle policy and many of those use France’s advanced disposal facilities, whereas the United States’ open fuel cycle policy means that its spent fuel is not reprocessed. After interim storage, such fuel will be disposed of in a deep geological repository. The US has not found a long-term place to store its nuclear waste. One proposed site was Yucca Mountain in Nevada, but the project faced many difficulties, including strong opposition from the public and local politicians.