The nuclear safety and the integrity of the Reactor Pressure Vessel (RPV) could be ensured by the In-Vessel Retention (IVR) strategy during the severe nuclear accident. The HEat transfer behavior of Light Metallic layer experiment for the Low aspect Ratio (HELM-LR) has been established to investigate the heat transfer characteristics and the concentration factor of the light metallic layer in a three-dimensional molten pool. The melt simulant is water. The test section is heated from below and can be cooled from both top and side. The experimental results demonstrate that the melt temperature increases along the vertical direction and decreases along the radial direction. The possible natural convection in the light metallic layer is formed, due to the temperature difference between the melt near the center and the melt near the sidewall. However, the effect of the natural convection would be limited with the low aspect ratio (H/D). Increasing the top cooling could lead to reducing the concentration factor (q_side/q_input). When the bottom heat flux is 1 MW/m² and the concentration factor is below 204%, the heat flux transferred to the AP1000 sidewall would not exceed the Critical Heat Flux (CHF) and the effect of IVR strategy would be enhanced. Consequently, it could avoid the vessel failure during the nuclear severe accident.

在发生严重核事故时，可以通过船内保留（IVR）策略来确保核安全和反应堆压力容器（RPV）的完整性。为了研究三维熔池中轻金属层的传热特性和富集系数，建立了低纵横比轻金属层的热传递行为实验（HELM-LR）。熔融模拟物是水。测试部分从下方加热，并且可以从顶部和侧面进行冷却。实验结果表明，熔体温度沿垂直方向升高而沿径向方向降低。由于中心附近的熔体和侧壁附近的熔体之间的温度差，在轻金属层中形成了可能的自然对流。然而，H / D）。增加顶部冷却量可能导致浓度系数降低（q_边/ q_输入）。当底部热通量为1 MW / m ²且浓度因子低于204％时，传递到AP1000侧壁的热通量不会超过临界热通量（CHF），IVR策略的效果会得到增强。因此，它可以避免核严重事故期间的船舶故障。