Coupled effects of initial temperature and sub‐atmospheric pressure on the flammability limits and explosion characteristics of Tributyl Phosphate/kerosene mixtures

Abstract TBP/kerosene mixtures are vital extraction solvents in nuclear fuel reprocessing, yet their explosion characteristics under coupled high temperature and sub‐atmospheric pressure are poorly understood. This study experimentally investigated the flammability limits and explosion intensities of these vapor mixtures at 60°C and 120°C (75–100 kPa, 0.75 bar‐1.0 bar). Results show that reducing initial pressure significantly suppresses explosion intensity and narrows the flammable range. At 120°C, the explosive range (1.0%–11.0% at 100 kPa) converges to a singular critical point (3.5% at 75 kPa); when at 60°C, the critical pressure threshold rises to 95 kPa. The maximum explosion pressure consistently occurred at a stoichiometric concentration of 7.0%. Sensitivity analysis indicates the upper flammability limit is more pressure‐sensitive than the lower flammability limit at 120°C, driven by reduced molecular collision frequency and oxygen limitation in fuel‐rich zones. These findings provide essential thermodynamic data for safety design and risk assessment in nuclear chemical facilities under extreme conditions.