Unit 1 of the two high-temperature gas-cooled reactors at China’s demonstration HTR-PM plant at Shidaowan, Shandong province, has achieved criticality 23 days after the start of fuel loading.
The unit is scheduled to be connected to the electricity grid before the end of the year. China Huaneng said the demonstration project will now conduct zero-power physical tests to verify the core and control rod performance and the availability of nuclear instrument monitoring system equipment. China Huaneng added it will "continue to standardise the follow-up commissioning and trial operation of the demonstration project to ensure the first grid-connected power generation in 2021."
Fuel loading had begun the day after an operating licence for the two-unit plant was issued by the National Nuclear Safety Administration. The two small reactors will drive a single 210MWe turbine. Helium gas is used as the primary circuit coolant.
China Huaneng is the lead organisation in the consortium building the units (with a 47.5% stake), together with China National Nuclear Corporation subsidiary China Nuclear Engineering Corporation (CNEC) (32.5%) and Tsinghua University's Institute of Nuclear and New Energy Technology (20%), which is the research and development leader. Chinergy, a joint venture of Tsinghua and CNEC, is the main contractor for the nuclear
The initial fuel loading of plant was divided into two stages, China Huaneng noted. The fuel elements were first loaded into a temporary fuel storage tank, and then transferred to the core through the fuel loading and unloading system. Over a period of some 30 days some 104,000 fuel elements were installed. A full load for a single reactor requires approximately 420,000 fuel elements.
China Huaneng said the plant uses a fully ceramic coated particle spherical fuel element indigenously developed. Each sphere contains 7g of uranium enriched to 8.5% with graphite as the matrix material. The core height is 11 metres and a diameter of 3 metres. There are two independent reactivity control systems: the primary one comprising 24 control rods in the side graphite reflector, and the secondary one of six channels for small absorber spheres falling by gravity, also in the side reflector. Fuel elements are released into the top of the core one by one with the reactor operating. Some graphite moderator pebbles the same size are included. They are correspondingly removed from the bottom, broken ones are separated, the burn-up is measured, and used fuel elements are screened out and transferred to storage.
Cold functional tests were completed at the HTR-PM's two reactors in October and November 2020 and hot functional tests began in January to simulate the thermal working conditions of the plant and verify that nuclear island and conventional equipment and systems meet design requirements. Testing of the steam turbine took place earlier in August.
China has been developing high temperature gas-cooled reactor (HTGR) technologies for more than 40 years, mainly at the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University in Beijing. Since the late 1980s, the National High-tech R&D Programme has designed, constructed, commissioned and operated a 10MW thermal power test reactor (HTR-10).
Based on the HTR-10 achievements, INET began development of a commercial nuclear power plant comprising modular HTGRs. The demonstration HTR-PM project was launched in 2001 and construction of the plant began in December 2012. A further 18 HTR-PM units are planned for the Shidaowan site.
China is also planning a larger HTGR. The HTR-PM600 will have a 650 MWe turbine driven by some six HTR-PM reactor units. Feasibility studies on HTR-PM600 deployment are under way for Sanmen, Zhejiang province; Ruijin, Jiangxi province; Xiapu and Wan'an, in Fujian province; and Bai'an, Guangdong province.