Cold functional tests are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition. The main purpose of these tests is to verify the leak-tightness of the primary circuit and components – such as pressure vessels, pipelines and valves of both the nuclear and conventional islands – and to clean the main circulation pipes. The tests mark the first time the reactor systems are operated together with the auxiliary systems.
“At 20:25 on 5 October, on the occasion of the Mid-Autumn Festival, the cold performance test of Unit 2 of the CGN Zhejiang Sanmao Nuclear Power Project was successfully completed,” China General Nuclear (CGN) said. “The primary circuit pressure boundary of the unit was intact and well sealed.”
Cold testing will now be followed by hot functional tests, which 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.
In September 2020, the executive meeting of China’s State Council approved the construction of units 1 and 2 as the first phase of the San’ao plant. China’s National Nuclear Safety Administration issued a construction permit for the two units on 30 December that year and first concrete for unit 1 was poured the following day. The first concrete for San’ao 2 was poured on 30 December 2021.
San’ao 1 and 2 are scheduled to begin supplying electricity in 2026 and 2027, respectively. Colding testing of unit 1 was completed in November 2024, with hot tests completed in June this year.
The construction site on San’ao 1 and 2 (Image CGN)
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 San’ao site. In August last year, the State Council approved the construction of San’ao Phase II (units 3 and 4).
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.
