China’s San’ao Unit 2 Completes Hot Testing Before Fuel Loading

Hot functional testing is the last big dry run before fuel goes into the core, and San’ao unit 2 has now cleared it at CGN’s Zhejiang plant on China’s eastern coast. The test confirms that the reactor can handle the temperature and pressure it will face in operation, while also checking coolant circuits, safety systems, and both nuclear island and conventional equipment against design requirements.

At San’ao, that matters because unit 2 is not a standalone demo machine. It is the second of six HPR1000, or Hualong One, units planned for the site, which sits about 90 km from Wenzhou and 35 km from Cangnan County. CGN has described the project as ultimately comprising six advanced units of about 1,000 MW each, and the International Atomic Energy Agency said the site employed about 1,000 workers during its pre-operational phase. That is a serious industrial buildout before the first long-run operating day ever arrives.

The commissioning sequence still has several gates to clear. After hot testing comes fuel loading, then first criticality, followed by power ascension work and the final steps toward grid delivery and commercial operation. For unit 2, CGN said the hot-test prerequisites were met at 17:18 on March 13, and the milestone marked entry into the critical performance verification phase before fuel loading. The schedule still points to electricity supply in 2027, so this is a major checkpoint, not a finished product.

The best reality check is unit 1. San’ao’s first Hualong One completed hot functional testing in June 2025, received its operating license on Dec. 24, 2025, reached first criticality on Feb. 14, 2026, and first connected to the grid on March 12. CGN said the unit was operating in good condition afterward and that technical indicators met design expectations. Unit 3 began construction in November 2025, so the site is already behaving like a multi-unit fleet rather than a one-off reactor project.

That is also why San’ao stands out beyond the commissioning calendar. It is the first nuclear power project in China’s Yangtze River Delta to use the Hualong One design, and it is China’s first nuclear project with minority private capital participation. Geely Technology Group’s investment arm holds a 2% stake in the first phase, while private capital participation in the second phase has reportedly risen to 10%. In an electricity-hungry industrial region, San’ao unit 2 passing hot tests says the project is still moving on the standard Hualong One path, and that path is now getting crowded.