蒸压加气混凝土在乏燃料容器坠落工况下的减振性能分析

Analysis of the Shock-Absorbing Performance of Autoclaved Aerated Concrete in the Condition of Spent Fuel Container Falling Off

在核电厂燃料厂房结构安全性分析中需考虑乏燃料容器坠落所产生的巨大冲击作用的影响,在坠落位置铺设蒸压加气混凝土砌体作为减振层是一种有效的结构防护方法.为了确定合理的减振层厚度并评价其减振效果,本文首先应用ANSYS/LS-DYNA对蒸压加气混凝土砌块的落锤冲击试验进行了有限元模拟,标定了蒸压加气混凝土的MAT96材料模型参数;再通过对减振层缩尺试验的模拟,验证了模拟方法的可行性;最终建立了燃料厂房分层壳模型,模拟设置不同厚度的减振层时乏燃料容器坠落对燃料厂房的冲击响应,并从坠落处楼板冲击力、混凝土应变、跨中挠度以及乏燃料水池加速度响应方面对厂房结构的安全性进行分析.分析结果表明:乏燃料容器坠落时,铺设1 m、2 m厚度的蒸压加气混凝土减振层后,减振效果显著:楼板冲击力分别减小71.5%和76.4%,楼板混凝土破坏明显减轻,跨中挠度明显减小,乏燃料水池竖向加速度峰值分别削减29.2%和43%;同时,2 m厚的减振层并未取得1 m厚度减振层2倍的减振效果.

In the process management of nuclear power plant, it is necessary to consider the huge impact effect to fuel plant when the spent fuel container falls off accidentally. In order to ensure the safety of fuel factory and spent fuel pool, a layer of autoclaved aerated concrete block with a certain thickness is laid at the down position as the damping layer to absorb the impact energy. It is a kind of simple and effective method. Firstly, the hammer impact test of autoclaved aerated concrete block was simulated to calibrate the parameters for constitutive model MAT96 in ANSYS/LS-DYNA. Secondly, the feasibility of the simulation method is further verified by the scale test model. Finally, a layered shell model of the fuel plant was established to simulate the impact effect of the spent fuel container falling off on the nuclear power plant. The analysis is made to obtain the impact force, the concrete principal strain, the deflection of the cross of raft, and the acceleration response of the spent fuel pool. The results show that the autoclaved aerated concrete layer at thickness of 1 meter and 2 meters can effectively mitigate the dynamic impact effect, with the impact force of raft decreasing by 71.5 % and 76.4 % respectively. The concrete damage and the deflection of the slab were significantly reduced, and the acceleration peak of the spent fuel pool decreases by 29.2 % and 43% respectively. However, the vibration damping effect for thickness of 2 meters is not as twice as that for1 meter.