Qinshan III units 1 and 2

On May 1, 2025, Unit 1 of the Qinshan Phase III nuclear power plant in Zhejiang province, near Shanghai, was taken offline after operating continuously for 738 days. This milestone set a new record for the longest uninterrupted operation of a power reactor in China and established a global record for a Candu-6 reactor, according to the China National Nuclear Corporation (CNNC).

The operating cycle, which began on April 24, 2023, saw Qinshan III Unit 1 generate over 12.5 billion kilowatt-hours of electricity. This output is equivalent to reducing standard coal consumption by 3.8 million tonnes and cutting carbon dioxide emissions by 9.97 million tonnes, CNNC reported. The achievement highlights the plant’s role in supporting sustainable energy production.

Candu-6 reactors, a type of pressurized heavy water reactor (PHWR), are designed to allow refueling without shutdowns. Nine such reactors operate globally, including units at Romania’s Cernavoda plant, Argentina’s Embalse plant, Canada’s Point Lepreau plant, South Korea’s Wolsong plant, and both units of China’s Qinshan III plant. The global record for continuous nuclear reactor operation is held by Canada’s Darlington Unit 1, another PHWR, which ran for 1,106 days until February 5, 2021.

Qinshan Phase III, primarily owned by CNNC, features two Candu-6 reactors built with Atomic Energy of Canada Limited (AECL) as the main contractor on a turnkey basis. Construction started in 1997, with Unit 1 beginning operations in September 2002 and Unit 2 in April 2003. As the reactors near the end of their 30-year design life, the Third Qinshan Nuclear Power Company is implementing a refurbishment program to extend their operational life by an additional 30 years.

The refurbishment involves upgrading the reactors’ fuel channels and auxiliary components. Candu reactors use a large horizontal calandria vessel with 480 tubes for high-temperature cooling water flow. Each tube has end fittings that allow isolation for fuel bundle replacement without shutting down the reactor. The refurbishment process requires dismantling thousands of components to ensure continued reliability and efficiency.

This record-breaking operation and ongoing refurbishment efforts demonstrate the Qinshan III plant’s commitment to providing stable, low-carbon energy while maintaining high operational standards. The project underscores advancements in nuclear technology and its contribution to sustainable energy goals.

by world nuclear news