Hot tests completed at second San'ao unit

Hot functional tests involve increasing the temperature of the reactor coolant system and carrying out comprehensive tests to ensure that coolant circuits and safety systems are operating as they should. Carried out before the loading of nuclear fuel, such testing simulates the thermal working conditions of the power plant and verifies that nuclear island and conventional equipment and systems meet design requirements.

China General Nuclear (CGN) announced that hot tests at San'ao unit 2 were successfully completed at 08:28 (local time) on Tuesday.

"The team fully drew on the experience feedback and best practices of unit 1 and previous projects, and worked together efficiently and with high quality to complete transient tests such as safety injection test, power switching test, and non-nuclear start-up test, as well as all tests required by the commissioning outline for this stage, achieving the goal of completing the hot commissioning in 51.9 months [since the pouring of first concrete for the nuclear island]," CGN noted.

Cold functional tests - which are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition - were completed at San'ao 2 in  October. The main purpose of those tests - which marked the first time the reactor systems were operated together with the auxiliary systems - was to verify the leak-tightness of the primary circuit.

_{The San'ao site (Image: CGN)}

First concrete for unit 1 was poured in December 2020, with that for unit 2 following a year later. Unit 1 achieved first criticality in February this year and was connected to the grid in March. San'ao 2 is scheduled to begin supplying electricity in 2027.

The San'ao plant is the first nuclear power project in China's Yangtze River Delta region to adopt the Hualong One reactor design. A total of six Hualong One units are planned for the site.

The construction of two Hualong Ones as units 3 and 4 of the San'ao plant was among plans for 11 reactors approved by China's State Council in August 2024. The first concrete was poured for the nuclear island of unit 3 on 19 December last year. A further two Hualong One units are planned as units 5 and 6.

Upon completion, the project will provide more than 54 TWh of electricity annually to Zhejiang Province and the Yangtze River Delta region, reducing standard coal consumption by more than 16 million tonnes and carbon dioxide emissions by more than 51 million tonnes annually, CGN noted.

The San'ao project marks the first Chinese nuclear power project involving private capital, with Geely Technology Group taking a 2% stake in the plant. CGN holds 46% of the shares of the project company Cangnan Nuclear Power, with other state-owned enterprises holding the remainder.