power plant
© Weibo/CPNNShidaowan's HTGR nuclear power plant
China's Shidaowan nuclear power plant, the world's first fourth-generation reactor, has begun commercial operations, one of the companies behind its development said.

The high temperature gas-cooled reactor (HTGR) went online following a week-long (168 hours) continuous operation test, state-owned China National Nuclear Corporation (CNNC) said in announcing the feat on Wednesday.

Fourth-generation nuclear reactors are designed to be successors for the existing, often water-cooled, nuclear reactors in operation around the world.

The reactor at the Shidaowan plant in China's eastern Shandong province is part of a global push for safer, more sustainable and efficient nuclear operations.

Instead of using water to cool the system, the high-temperature reactor will be cooled using helium gas, offering a promising way to develop more inland nuclear plants, as they will not need to be located next to a water source.

High-temperature reactors can produce heat, power, and hydrogen, and would help China and the world "become carbon neutral", said Zhang Zuoyi, dean of the Tsinghua University Institute of Nuclear and New Energy Technology and chief designer of the Shidaowan reactor project. CNNC, Tsinghua and state-owned China Huaneng Group are the joint developers and operators of the plant.

The facility, which began construction in 2012, features two 250 megawatt thermal reactors and a steam generator with an installed capacity of 200 megawatts, according to CNNC. Up to 93.4 per cent of the material used in the Shidaowan HTGR was domestically sourced, the company said.

A feature of the reactor's design is "inherent safety", as in the event of a sudden reactor failure or external disturbance, "the core will not melt," a Tsinghua press release said.

Fourth-generation reactors aim to limit the environmental impact, nuclear waste burden, risk of nuclear meltdown, and opportunities for nuclear proliferation, according to the Gen IV International Forum (GIF), an international cooperative framework of major nuclear nations.

The GIF, initiated by the US Department of Energy in 2000, represents 13 nuclear nations - including China, France, Japan and Russia - along with the European Union.

Fourth-generation reactors are intended to operate at higher temperatures than most of the reactors around the world today, which allows them to generate both electricity and hydrogen, according to the GIF.

The GIF has identified six types of nuclear technology that represent the fourth-generation, and most countries in the framework are committed to producing at least one.

Apart from gas reactors like the Shidaowan HTGR, which use helium to cool, there are also lead, molten-salt or sodium-cooled fast reactors, capable of turning nuclear waste into fuel, and supercritical water-cooled reactors - which directly use water to drive a turbine instead of steam for electricity generation.

Reactors like Shidaowan will be able to produce hydrogen alongside electricity for the grid. Hydrogen produced by the reactors can be used as fuel, as well as in a variety of industrial applications.

Most hydrogen produced in the world today is made from carbon-based materials and therefore creates carbon dioxide emissions, according to the World Nuclear Association.

However, high temperature reactors can use thermochemical processes to produce zero-carbon hydrogen using water.

inside Shidaowan NP
© Weibo/CPNNInside view of Shidaowan nuclear plant
While Shidaowan is the world's first HTGR to enter commercial operation, other Chinese fourth-generation plants may soon be on their way.

In southeast China's Fujian province, the CNNC-managed Xiapu sodium-cooled fast reactor pilot project is also under construction, and is expected to be connected to the grid by 2025. Unlike the HTGRs, sodium-cooled fast reactors are able to recycle depleted uranium, allowing the fuel to be reused again.

There are other sodium-cooled reactors in operation in the world, but they are third-generation.

Other fourth-generation nuclear reactor projects are undergoing research and design in the United States, Japan, and Canada, but have yet to begin construction, according to the International Energy Agency.

China has been increasing its nuclear capacity at the highest rate globally. However, as of this year, nuclear power still made up only 5 per cent of China's energy generation as the country continues to rely on coal, according to the World Nuclear Association.

Lu Hua Quan, chairman of the Nuclear Research Institute at Huaneng, told the association last year that HTGRs had "great potential to help the world decarbonise hard-to-abate sectors". However, safeguards and waste management, as well as regulatory frameworks, still need to be addressed if the technology is to be broadly deployed.

Lu said HTGRs could be very helpful in countries where freshwater was limited, as it did not require large amounts of it in order to cool the reactors.

And for nations where large capacity nuclear plants do not fit into local power grids, the ability to create small modular reactions can be built with smaller capacities that suit the needs of the power grid, he said.