Passive safety modules installed at Chinese units

Thursday, 6 March 2025

In the event of leakage in the primary circuit the passive heat removal system assures the transition of 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 3 consists of four modules, each of which is composed of reinforced concrete slabs, stainless steel cladding, penetrations, heat exchangers, and wall reinforcements. 

The four modules were hoisted into place on 25 February, China National Nuclear Corporation (CNNC) subsidiary China Nuclear Power Engineering Company Limited (CNPEC) announced.

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.

The installation of the tank marks "a key step in the main civil construction work of the nuclear island building of unit 3, creating favourable conditions for subsequent major nodes such as cold tests and hot tests", CNPEC said.

In June 2018, Russia and China signed four agreements, including for the construction of two VVER-1200 reactors at the new Xudabao (also known as Xudapu) site. Agreements signed in June 2019 included a general contract for the construction of Xudabao units 3 and 4, as well as a contract for the supply of nuclear fuel.

Construction of Xudabao unit 3 began in July 2021, with that of unit 4 starting in May 2022. Commissioning of the units is scheduled for 2027 and 2028, respectively.

The Xudabao plant is owned by Liaoning Nuclear Power Company Limited, a joint venture between CNNC (70%), Datang International Power Generation Company (20%) and State Development and Investment Corporation (10%).

Module installed at Zhangzhou 3
 

CNNC announced the first module of the passive reactor cavity water injection tank of reactor building of Zhangzhou unit 3 was successfully hoisted on 2 March.

_{(Image: CNNC)}

"Based on the experience gained from the construction of the first phase of the Zhangzhou Nuclear Power Project, CNNC Zhangzhou Energy continues to promote the fully modular construction technology of stainless steel water pools," it said.

The passive reactor cavity water injection tank is an important component of the reactor cavity cooling system. The water tank is a fully enclosed fan-shaped structure. During its construction, cutting-edge technologies such as automatic welding technology for stainless steel coverings, customised support trusses, and overall modular construction technology were applied. It was hoisted into place as a whole by a 2000-tonne crawler crane.

Zhangzhou 3 is the third of four Hualong One units being built at the site. Construction of Zhangzhou 1 began in October 2019, with that of unit 2 starting in September 2020. Unit 1 entered commercial operation on 1 January this year, while unit 2 is scheduled to enter commercial operation by the end of 2025. In September 2022, China's State Council approved the construction of two Hualong One units as Phase II - units 3 and 4 - of the Zhangzhou plant. Construction of unit 3 began in February last year, with that of unit 4 starting in September.

The Zhangzhou project - with a total investment of over CNY100 billion (USD14 billion) - is owned by CNNC-Guodian Zhangzhou Energy Company, a joint venture between CNNC (51%) and China Guodian Corporation (49%).