A team of government researchers in China have unveiled the design for a commercial nuclear reactor that is expected to be the first in the world that does not need water for cooling, the South China Morning Post (SCMP) reported on 19 July. This will allow the facilities to be built in remote desert regions to provide power for more densely populated areas. The design includes a molten salt reactor, which is powered by liquid thorium rather than uranium, making it safer in the event of a leak. The molten thorium would cool and solidify quickly, dispersing less radiation into the environment. Construction of the first commercial reactor should be completed by 2030 and the government plans to build several in the deserts and plains of central and western China, SCNP noted.
China may also consider building these reactors for countries that have signed up to the Belt and Road Initiative because, unlike uranium, thorium cannot be used to make nuclear weapons.
“Small-scale reactors have significant advantages in terms of efficiency, flexibility and economy,” Professor Yan Rui and colleagues at the Shanghai Institute of Applied Physics wrote in a paper published recently in the Chinese journal Nuclear Techniques. “They can play a key role in the future transition to clean energy. It is expected that small-scale reactors will be widely deployed in the next few years.” A molten salt reactor has the advantage of being multipurpose, small in size and highly flexible. It is as easy to design as a small-scale reactor. In recent years, the potential of small-scale molten salt reactors has caught international attention, the scientists noted.
A key driver for the molten salt reactor programme was President Xi Jinping’s announcement in 2020 that China would become carbon neutral by 2060, according to scientists involved in the project.
Under the official plan, reactors in the sparsely populated west of the country will provide a clean, stable electricity supply to the densely populated east in combination with wind and solar power plants.
The concept of a reactor powered by liquid salt rather than solid fuel first appeared in the 1940s, and in the 1950s the USA started an experimental programme and in the 1960s built a facility to test the technology’s capacity to generate electricity. France, the former Soviet Union and Japan launched similar programmes. However, these early projects failed because they could not solve problems such as pipes cracking because they had become corroded by the radioactive molten salt.
In 2011, Beijing approved the construction of the prototype Thorium Molten Salt Reactor (TMSR), in Wuwei, a desert city in Gansu province. Meanwhile, teams of researchers from across the country were mobilised to solve the technical problems revealed by the earlier experiments. These included development of an alloy that can withstand the radiation from thorium salt at temperatures of nearly 1,000 degrees Celsius. Although the project fell behind schedule, in part due to the pandemic, construction work on the TMSR is due to finish next month and a test run of equipment could start in September.
Although the prototype is only capable of generating 2MW, if it succeeds it will be the first time theory has been put into practice.
China plans to link the reactors with wind and solar plants to power more densely populated areas. The commercial reactor designed by Yan and his colleagues could generate up to 100MW, less than a conventional uranium-fuelled reactor but still enough to power a residential area with 100,000 inhabitants.
Though a power plant will need other equipment, such as steam turbines, the reactor will only be 3 metres tall and 2.5 metres wide.
It works by allowing the thorium to flow through the reactor, participating in a nuclear chain reaction and transferring the heat to a steam generator outside before returning to the reactor for another cycle. It is safer than traditional nuclear technology because in the event of an accident the molten salt will fall into an underground container. “Due to its high melting point … the molten salt will quickly cool and solidify without the direct release of solid and liquid effluents, thus preventing the further diffusion of radioactivity into the environment,” the scientists wrote.
China has some of the world’s largest reserves of thorium, a silvery metal with weak radioactivity. By some calculations it has enough to meet the country’s energy needs for at least 20,000 years. By contrast, China has some of the lowest uranium reserves of any nuclear-capable country