China's Tianwan 7 connected to the grid

The delivery of the first electricity to the grid from the VVER-1200 reactor on 8 October took place just over a week after it achieved a self-sustaining controlled nuclear chain reaction and was brought to a minimum controllable power level.

China National Nuclear Corporation (CNNC) said that throughout construction of the Sino-Russian project "all parties, maintained a rigorous and meticulous work attitude, and collaboratively completed key operations such as reactor protection logic verification, reactor criticality, turbine start-up, and generator short-circuit test. Subsequently, the unit will conduct a series of tests as planned to further verify its performance and ensure it meets the conditions for commercial operation".

Power at the unit at the plant - which is on the coast in Jiangsu province - will be increased in stages, with tests and checks at each level until it gets to full power and commercial operation.

The background

In June 2018, Russia and China signed agreements for the construction of two VVER-1200 reactors as units 7 and 8 of the Tianwan plant. Construction of unit 7 began in May 2021, with that of unit 8 starting in February 2022. The units were scheduled to be put into commercial operation in 2026 and 2027, respectively.

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

_{(Image: CNNC)}

The first four units at the Tianwan site - which began commercial operation between June 2007 and December 2018 - are Gidropress VVER units supplied by Russia. Units 5 and 6 both feature Chinese ACPR1000 reactors.

In January, CNNC announced that hot tests - which simulate the temperatures and pressures the reactor systems will be subjected to during normal operation - had been completed at unit 7 on 30 December. Cold tests - which verify the leak-tightness of the primary circuit and components - were completed at unit 8 earlier this month.

Once all units at the Tianwan plant are operational, the total installed capacity will exceed 9 GWe, with an annual power generation of over 70 TWh, reducing carbon dioxide emissions by 57.4 million tonnes annually.