Reactor internals installed at Haiyang 4

Friday, 27 June 2025

Reactor internals are the major structures within a reactor pressure vessel that have one or more functions such as supporting the core, maintaining fuel alignment, directing primary coolant flow, providing radiation shields for the reactor vessel, and guiding in-core instrumentation.

The reactor internals for Haiyang 4 – with a total hoisting weight of about 260 tonnes – were hoisted into the unit’s reactor building on 24 June in a process lasting 2 hours and 31 minutes, China National Nuclear Corporation announced.

The construction of two CAP1000 reactors – the Chinese version of the Westinghouse AP1000 – as units 3 and 4 of the Haiyang plant was approved by the country’s State Council on 20 April 2022.

The first safety-related concrete was poured for the nuclear island of Haiyang unit 3 in July 2022. The reactor pressure vessel was installed in unit 3 in December 2023. Construction of Haiyang 4 began in April 2023. The two units are scheduled to be fully operational in 2027.

The 281-tonne reactor pressure vessel – which houses the internals – was hoisted by a 3,200-tonne crawler crane and placed inside the reactor building in November last year.