Experimental investigation on thermal-hydraulic interaction between subcooled water and high-temperature lead‑bismuth eutectic under steam generator tube rupture accident

The mechanisms of direct-contact boiling between subcooled water and high-temperature lead‑bismuth eutectic (LBE) during the steam generator tube rupture (SGTR) remain partially unclear. This study experimentally investigated the direct-contact boiling process induced by water injection into a large-volume high-temperature LBE pool, focusing on the resulting dynamic pressure wave in LBE, pressure rise in gas, and temperature distribution. Eleven experimental cases were conducted under varying conditions of injection nozzle diameter (5–10 mm), LBE temperature (270–400 °C), secondary-side water pressure (3.1–5.8 MPa), secondary-side water temperature (28–85 °C), and gas-to-LBE volume ratio (2:3–3:2). Observations revealed non-uniform vapor cavity expansion, entrainment of subcooled water in gas cavities, and attenuation of dynamic pressure waves. The peak dynamic pressures at different measurement locations (PS1 and PS2) were observed in distinct peak segments. Specifically, the peak at PS1 occurred within the first segment, while that at PS2 appeared in the second or third, which suggested the presence of pressure wave superposition effects. Quantitative relationships were established through empirical correlations, which demonstrated that the LBE temperature, water temperature, and gas-to-LBE volume ratio are positively correlated with the LBE dynamic pressure peak, which ranged from 1.670 to 3.368 MPa. The derived impact indices for these three parameters in the power-law correlations are 0.99, 0.99, and 0.17, respectively. Injection nozzle diameter, LBE temperature, water pressure, and water temperature are positively correlated with the average pressurization rate (0.511–1.122 MPa/s) in the reaction vessel, while gas-to-LBE volume ratio exhibits a clear negative correlation. The findings contribute to clarifying the mechanisms of direct-contact interactions between subcooled water and high-temperature liquid metals.