Effect of different conditions on heat transfer characteristics of molten Zr-Stainless steel pool with water injection

Highlights: • Different mass percentages of Zr are used as the melt simulant. • Effect of different conditions of water injection on the heat transfer are studied. • Heat flux removed by water ranges from about 800 to 1400 kW/m². • Water injection could mitigate the thermal focusing effect. • Neither vapor explosion nor melt ejection occurs for all the tests. External Reactor Vessel Cooling (ERVC) could be accompanied by the in-vessel water injection to alleviate the thermal focusing effect of the light metallic layer and enhance the In-Vessel Retention (IVR) strategy. Through the wATer injectiOn on molten Zirconium-Stainless steel Metallic pool experiment (ATOM), the effects of different temperatures, mass flow rates of water injection, and different mass percentages of Zr on the heat transfer characteristics after water injection have been investigated. The mass flow rate of water injection ranges from 0.05 kg/s to 0.10 kg/s, and the mass percentage of Zr ranges from 13% to 60%. Eight tests were carried out, and the maximum upward heat flux removed from the melt surface ranged from around 800 to 1400 kW/m². A higher water injection mass flow rate and a lower Zr mass percentage could lead to a higher steam generation rate. After water injection, the experimental melt temperature and concentration factor decrease. By applying the ATOM heat transfer coefficient as the input data in the nuclear reactor case, the calculated results indicate that the thermal focusing effect inducing by the decrease of the light metallic layer's height could be highly mitigated by water injection. As a result, the integrity of the RPV could be enhanced. During the whole experiment for all the tests, no vapor explosion and melt ejection were found.