Analytical Investigation On Numerical Simulation Of Expanding Process Of Tube-to-Tubesheet For Steam Generator And Passive Heat Exchanger In AP1000 Nuclear Power

By using the three-dimensional finite element simulation, the expanding process and joint performance at different technological parameters have been simulated for steam generator and passive heat exchanger in AP1000 nuclear power. Based on this, the determination method of expanding process parameters has been investigated. The main research work and the results obtained are as follows:(1) The effects of expansion pressure, initial clearance and mechanical properties of materials on residual contact pressure at the interface of joints, pull-out strength, the residual stress at the transition zone and the wall reduction have been investigated. The result shows that, with increasing the expansion pressure, the residual contact pressure, the pull-out force and the wall reduction increase linearly. With increasing the initial clearance, residual contact pressure at the interface of joints and pull-out strength decrease, the wall reduction increases. The yield stress of Alloy690 tube material has certain effect on expanding mechanical parameters, while A508 tubesheet material has no effect on them.(2) The quantitative equations between expansion pressure, initial clearance and mechanical properties of materials on residual contact pressure at the interface of joints, pull-out strength, and the wall reduction were obtained. Based on these equations, the determination method of expanding process of the AP1000 steam generator and passive heat exchanger has been established.(3) The little expanding process in the secondary surface of tube-to-tubesheet joints have been simulated and investigated for AP1000 steam generator. The little expanding process parameters that can be used for joints with different expansion pressure and different initial clearance were obtained.