World’s first high temperature gas-cooled reactor connected to grid in China

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The world’s first land-based small modular reactor (SMR) has been connected to the grid in China earlier this month, the state-run China National Nuclear Corporation (CNNC) has announced.  

It is the first unit of Shidao Bay nuclear power plant (NPP) in northeast China’s Shandong province, with a generation capacity of 200 MW. A second such unit is under construction.  

Built by the state-run power generator China Huaneng Group (CHGC) in collaboration with Beijing’s Tsinghua University, the SMR becomes the world’s first pebble-bed modular high-temperature gas-cooled reactor to be connected to the grid. 

As it is cooled by helium gas, this high-temperature gas-cooled (HTR-PM) small modular reactor can be used in inland areas away from large bodies of water. The HTR-PM is a Generation 4 reactor design and is a part of the nation’s drive to make China carbon-neutral by 2060. 

In pebble-bed technology, the reactor core is formed from graphite pebbles that contain specially designed fuel particles. CNNC said the design allows reactors to be run safely at higher temperatures, describing it as “the reactor that won’t melt down”.  

The CNNC also said that the technology at the Shidao Bay project was completely indigenous, with 93.4 percent of the equipment having been sourced domestically. The China Huaneng Group plans to develop the two HTR-PM reactors at this demonstration plant to jointly power a 210 MW turbine. 

According to the CHGC, the demonstration project used more than 2,000 sets of equipment for the first time, and more than 600 sets of innovative equipment, including the world’s first high-temperature gas-cooled reactor spiral coil steam generator. It also features the first high-power, high-temperature thermal electromagnetic bearing structure for the main helium fan, as well as the world’s largest and heaviest reactor pressure vessel.   

The Chinese nuclear regulator, the National Nuclear Safety Administration, issued an operating license for the HTR-PM in August 2021, which was followed by the loading of the first spherical fuel elements into the first reactor, and the start up in September.

A total of 18 such reactors are planned at Shidao Bay. China is also proposing a scaled-up version called the HTR-PM-600, in which one large turbine will be driven by six HTR-PM units to generate 650 MW electricity.  

According to the International Atomic Energy Agency (IAEA), being cooled by helium and capable of reaching temperatures as high as 750 degrees Celsius, makes the HTMR suitable for non-electric applications such as district heating and hydrogen production. The reactor is also designed with inherent safety features that reduce the risk of radioactive releases.  

An IAEA report says that safety is also a matter of fuel design and how the nuclear fission reaction is controlled in the reactor core. According to the agency, modular high-temperature gas-cooled reactors (MHTGR) being small in size, with predesigned geometrical restrictions and limitations of the reactor and fuel elements, are inherently safe owing to their design features. Besides, their power density is low, while minimal fuel is available in the reactor. Moreover, the chances of core damage of the MHTGR are nil, according to the IAEA.  

Among the Asian nations, taking the case of India which has plentiful thorium reserves, the IAEA has specifically pointed out that small thorium-based gas cooled high temperature reactors (STGRs) in the 20MW-40MW range are completely safe with a core damage frequency rate of zero. The agency has reiterated that such SMRs merit introduction in India not only for their innovative technology, but also for other economic benefits of the STGRs. An IAEA report says that “for 10,000 STGRs in India, the combined core damage frequency (CDF) will still be 0.”