The final module of the passive water tank has been installed within the reactor building of Unit 4 at the Xudabao nuclear power plant in China’s Liaoning Province, China National Nuclear Corporation announced.
In the event of leakage in the primary circuit, the passive heat removal system assures the transition of the steam generators to operation in the mode of condensation of the primary circuit steam. As a result, the condensate from steam generators arrives at the core, providing additional cooling.
The passive water tank of the reactor building of Xudabao unit 4 consists of four modules, each of which is composed of reinforced concrete slabs, stainless steel cladding, penetrations, heat exchangers, and wall reinforcements. The hoisting weight of a single water tank module is 325.9 tonnes. The completed tank features 33 penetrations and 16 heat exchangers arranged within it.
China National Nuclear Corporation (CNNC) said the installation of a passive water tank marks “the full completion of the modular construction of large components for the second phase of the Xudabao nuclear power project, which lasted four years”.
The Xudabao (also known as Xudapu) project was originally expected to comprise six CAP1000 reactors- the Chinese version of the Westinghouse AP1000 – with units 1 and 2 in the first phase. Site preparation began in November 2010. The National Development and Reform Commission gave its approval for the project in January 2011. However, with a change in plans, construction of two Russian-supplied VVER-1200 reactors as Xudabao Phase II (units 3 and 4) began in July 2021 and May 2022, respectively. Commissioning of the units is scheduled for 2027 and 2028, respectively.