Study On Structure Module Installation Of AP1000 Nuclear Plant

In accordance with China’s energy construction and nuclear power development strategic objectives,a number of third generation nuclear power units will be built.AP1000 is an internationally advanced "passive pressurized water reactor(PWR)nuclear power technology" introduced at the national level.The use of modular construction techniques is an important feature of the AP1000.During the construction of AP1000 nuclear power units,some problems occurred in the module assembly and installation.The main problems are: the welding deformation of the reactor chamber module flange during the assembly process is large,and the size does not meet the design requirements;After lifting and placing in place,the southwest wall module of the refueling tank is seriously deformed,which seriously affects the construction progress of the unit.Therefore,it is of great significance for China’s nuclear power construction and energy development to explore technical solutions and measures to solve the problems existing in the installation process of AP1000 structural modules.This paper briefly introduces the assembly process and welding deformation of AP1000 module.According to the structural characteristics of the reactor chamber module,the welding simulation experiment was carried out.Based on the analysis of the monitoring data of the welding simulation test,the measures to control the welding deformation were obtained: the total amount of welding heat input could be effectively reduced by reducing the gap between welding groups and welding rod with a diameter of 3.2mm,so as to reduce the welding deformation.The heat input position distribution of the main welding seam can be adjusted by using X groove,cross welding main welding seam,step by step assembly welding,and adjusting the welding position according to the process monitoring dimension,which can effectively reduce the welding deformation.Set the appropriate reverse deformation dimension and install the fixed fixture to reduce the welding deformationUsing the PDCA research method,it is concluded that the main reasons for the lifting deformation of the southwest wall module of the feed tank are as follows: first,the lifting center of gravity of the module does not take into account the weight of other parts installed on the module on site,resulting in the unbalanced lifting and additional stress resulting in the lifting deformation of the module;The second is the abnormal shape of the module structure,self-rigid,no reinforcement measures.On the first main reason,through calculating the refueling tank southwest wall module assembly final focus,adjustable two stage was proposed and designed for hanging beam sling(first level : 400 t crane beam,second level:200 t crane beam)can make southwest of refueling tank wall module hoisting process balance,to prevent the extra stress lead to deformation,and sling for the security check;According to the second reason,designed the hoisting anti-deformation support(deformation of support for prevention,middle and lower three layers,which HW200×200×12×8 steel as the main body,16# channel steel and 7.5#Anglesteel secondary connection structure),established the installation prevents deformation finite element model of supporting module hoisting,finite element calculation show that installing anti-deformation support greatly reduces the maximum stress in the module assembly,from 232 MPa to 141.457 MPa,to verify the installation of anti-deformation support can effectively reduce the deformation of hoisting module.In addition,the lifting space of anti-deformation support is verified,which does not affect the lifting of the module.