Unit 1 of the Sanmen nuclear power plant in China has been connected to the grid, becoming the world's first AP1000 to achieve grid connection and power generation. The milestone came just one day after Taishan 1, also in China, became the first EPR to reach the same milestone.

Sanmen units 1 and 2 (Image: Westinghouse)

Sanmen 1 was connected to the grid for the first time at 4.48pm on 30 June, Westinghouse and its Chinese customers China State Nuclear Power Technology Corporation and China National Nuclear Corporation have announced.

"Sanmen 1's turbine generator is now initially connected to the electrical grid and has begun generating electricity," Westinghouse said.

"The technical indicators met the design requirements and the reactor status was well controlled, indicating the unit's construction formally entered the grid-connected commissioning phase for subsequent operation at various power levels," China's National Nuclear Safety Administration (NNSA) said. "The milestone has laid a solid foundation for transient testing and scheduled commercial operation."

Hot testing of Sanmen 1 was completed in June last year. The loading of fuel assemblies into its core began on 25 April following the issuance of a permit by the NNSA. The unit achieved first criticality - a sustained chain reaction - on 21 June. On 27 June, nuclear-generated steam was used for the first time to successfully rotate the turbine at rated speed.

The unit will now undergo gradual power ascension testing until all testing is safely and successfully completed at 100% power. Sanmen 1 is scheduled to enter commercial operation by the end of this year.

Westinghouse President and CEO José Gutiérrez said, "Today we witness our first AP1000 plant, Sanmen 1, began its process of generating electricity and providing our customers in China with safe, reliable and clean energy. This milestone would not have been possible without the constant collaboration and partnership with our China customer."

David Durham, senior vice president of Westinghouse's New Projects Business, said: "It's such an exciting time for Westinghouse, our China customer and the nuclear industry, as we proudly move closer and closer to 100% power and commercial operation at Sanmen 1."

In September 2007, Westinghouse and its partner the Shaw Group received authorisation to construct four AP1000 units in China: two at Sanmen in Zhejiang province and two more at Haiyang in Shandong province. Construction of Sanmen 1 began in April 2009, while first concrete for Sanmen 2 was poured in December 2009. Construction of Haiyang 1 and 2 began in September 2009 and June 2010, respectively.

Hot tests at Sanmen 2 were completed in January. That unit is also expected to begin operating by the end of this year.

The loading of the 157 fuel assemblies into the core of Haiyang 1 began on 21 June. The unit is also expected to begin operating by year-end, with Haiyang 2 expected to start up in 2019.

Four AP1000 reactors were also being built in the USA - two each at Vogtle and Summer. However, construction of the two Summer units was suspended last August.