The first of two core replenishment tanks has been lifted into place at unit 3 of China's Sanmen NPP in Zhejiang province, the Shanghai Nuclear Engineering Research & Design Institute (SNERDI) announced. The tanks are an important part of the CAP1000 reactor's passive safety system. SNERDI noted that each CAP1000 unit contains two water replenishment tanks, A & B. They are mainly used to release boronated water in the event of an accident to ensure the effective cooling of the core.
"Due to the complex installation environment of the core water tank, which is surrounded by multiple modular steel beams and structural embedded parts, SNERDI conducted a comprehensive analysis of the lifting process in advance to formulate solutions to any possible problems," it said. "Three-dimensional simulation was used to identify and remove any items that could interfere with the lifting to ensure the work proceeded safely and efficiently. At the same time, innovative construction technology, the use of milling machine block processing, with appropriately sized pads, effectively solved the problems caused by the uneven foundation.
The CAP1000 is China’s version of the Westinghouse AP1000. It uses modular construction techniques, enabling large structural modules to be built at factories and then installed at the site. This reduces construction time and improves quality control.
The construction of two new units at each of the Sanmen (3&4), Haiyang (3&4) and Lufeng (5&6) NPPs was approved by China's State Council in April 2021. Two Westinghouse AP1000 units built as Phase I of the Sanmen plant (1&2) started operation in 2018. Two CAP1000 reactors are being constructed as Phase II of the plant (units 3&4). First concrete was poured for the nuclear island of Sanmen 3 in June 2022 and for unit 4 in March 2023.
Image: The replenishment tanks are an important part of the CAP1000 reactor's passive safety system (courtesy of SNERDI)
