Unit 5 of the Tianwan nuclear power plant in China's Jiangsu province has attained a sustained chain reaction for the first time. The 1080 MWe domestically-designed ACPR1000 pressurised water reactor is expected to be connected to the grid later this year, after which it will enter commercial operation.

Control room operators bring Tianwan 5 to criticality (Image: CNNC)

Tianwan 5 achieved first criticality at 8:20am on 27 July, Jiangsu Nuclear Power Corporation has announced. The company said the milestone "marks the completion of the commissioning of the overall system and equipment of the unit, and the unit has officially entered a continuous and controllable nuclear operation state."

It added, "This is another major milestone completed by Tianwan nuclear power unit 5 after the first fuel loading, laying a solid foundation for the subsequent grid connection and commercial operation of the unit."

Units 5 and 6 at Tianwan - Tianwan Phase III - both feature ACPR1000 reactors. First safety-related concrete was poured for unit 5 on 27 December 2015, with that for unit 6 poured on 7 September 2016. China National Nuclear Corporation (CNNC) plans to put both units 5 and 6 into commercial operation by the end of 2021. China's National Nuclear Safety Administration issued a 40-year operating licence for Tianwan 5 on 7 July. The loading of fuel into the unit's core was completed two days later.

Tianwan units 5 and 6 (Image: CNNC)

The first four units at the Tianwan site are Gidropress VVER units supplied by Russia, as will be the seventh and eighth.

Tianwan Phase I - units 1 and 2 - was constructed under a 1992 cooperation agreement between China and Russia. First concrete was poured in October 1999, and the units were commissioned in June 2007 and September 2007, respectively. Tianwan Phase II - units 3 and 4 - are similar to the first stage of the Tianwan plant, comprising two Russian-designed 1060 MWe VVER-1000 PWRs. First concrete for unit 3 was poured in December 2012, while construction of the fourth unit began in September 2013. Unit 3 entered commercial operation in February 2018, with unit 4 following in December.

In March 2019, a general contract for Phase IV - units 7 and 8 - of the Tianwan plant was signed between AtomStroyExport, the engineering division of Russian state nuclear corporation Rosatom, and CNNC.

Jiangsu Nuclear Power Corporation is a joint venture between CNNC (50%), China Power Investment Corporation (30%) and Jiangsu Guoxin Group (20%).

Researched and written by World Nuclear News