Hot testing completed at sixth Tianwan unit

Hot functional testing of Tianwan 6 began on 28 November. These tests involved 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.

These tests were completed on 29 December, China National Nuclear Corporation (CNNC) announced the following day. "The whole hot test process was finely operated and seamlessly connected with various tests, and all test verifications were successfully completed," it said.

Cold functional tests - which are carried out to confirm whether components and systems important to safety are properly installed and ready to operate in a cold condition - were completed at Tianwan 6 on 4 October. The main purpose of those tests was to verify the leak-tightness of the primary circuit.

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. Tianwan 5 entered commercial operation in September last year, with unit 6 expected to follow by the end of 2021.

The first four units at the site - which began commercial operation between June 2007 and December 2018 - are Gidropress VVER units supplied by Russia, as will be the seventh and eighth, for which a general contract was signed in March 2020.

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%).