Dome in place at first San'ao unit
![Dome in place at first San'ao unit](/images/articles/San-ao-1-dome-hoisting-(CGN).jpg)
The dome is a key component of the third safety barrier of the nuclear power plant, ensuring the integrity and sealing of the reactor building and realising the inherent safety characteristics, China General Nuclear Power Group (CGN) said.
The operation to hoist the dome, which is 45 metres in diameter, to a height of 70 metres and moving it into place is a high-precision task, with challenges including wind conditions and thermal expansion and contraction due to changing temperatures.
"It's like using a crane to thread an embroidery needle," Zhong Hongjin, senior engineer in charge of nuclear island civil works at CGN Cangnan Nuclear Power Co, Ltd.
Two Hualong One units are currently under construction at San'ao, which is near Cangnan county on the coast of Zhejiang province. Construction of unit 1 began at the end of 2020, with unit 2 following a year later. The units are currently expected to begin operation in 2026 and 2027 respectively.
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