Discussion on the assembly and installation of passive pressurized water reactor water storage tank

CB20 large structural module which is the passive pressurized water reactor water storage tank is the main structure of AP1000 nuclear power plant building, and its cross-section is a trapezoidal barrel structure module. CB20 module has the features of over-sized submodule, complicated structure and difficult anti-deformation control and large welding quantity etc. After the installation and setting of CB20, the theoretical water storage capacity of PCCWST (PCS-Passive Containment Cooling System) will be 2970 t. After the installation, PCCWST and shield wall are integrated by the concrete placement, the PCCWST will be used to store spray water for cooling. The stored water can ensure the 72 hours continuing spraying. Therefore, it is crucial to ensure the construction quality during module assembly, so as to ensure final installation quality. This article describes the main assembly and installation process of CB20 module, analyses the difficulties during the assembly and proposes a series of solutions to water storage tank module assembly platform, sub-module delivery dimension, diagonal plate fitting-up sequence, welding deformation control, key dimension control as well as installation construction activities etc, so as to supply construction experience for the other water storage tank assembly and installation and improve and innovate previous construction process. (authors)