The third and final steam generator has been installed at unit 6 of the Tianwan nuclear power plant in China's Jiangsu province. The ACPR1000 reactor is scheduled to enter commercial operation by the end of 2021.

Installation of the third steam generator at Tianwan 6 (Image: CNI23)

Steam generators are used in pressurised water reactors to transfer heat from the reactor coolant into water in a secondary circuit, producing the steam used to power the electricity-generating turbines. Each steam generator contains thousands of kilometres of tubes through which hot water flows.

The final steam generator - almost 21 meters in height and weighing more than 300 tonnes - was hoisted into place on its vertical support within the reactor building of Tianwan 6 on 9 May, China Nuclear Industry 23 Construction Company Limited (CNI23) has announced.

The first two steam generators were installed on 25 February and 8 April, respectively. CNI23 said installation of the steam generators has laid "a solid foundation for the subsequent welding of the hot and transition sections of the main pipeline".

Units 5 and 6 at Tianwan - Tianwan Phase III - are domestically-designed ACPR1000 pressurised water reactors that will produce 1080 MWe when commissioned. 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.

The first four units at the site are Gidropress VVER units supplied by Russia, as will be the seventh and eighth, for which a general contract was signed in March.

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 pressurised water reactors. 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 this year, 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.

When all eight units are in operation Tianwan would become the largest nuclear power plant in the world with eight units and a total generating capacity of about 8100 MWe.

The Tianwan plant is owned and operated by Jiangsu Nuclear Power Corporation, a joint venture between CNNC (50%), China Power Investment Corporation (30%) and Jiangsu Guoxin Group (20%).

The third and final steam generator has been installed at unit 6 of the Tianwan nuclear power plant in China's Jiangsu province. The ACPR1000 reactor is scheduled to enter commercial operation by the end of 2021.