Existence of Steady-State Fuel-Coolant Thermal Detonation Waves

The possibility of a steady-state Chapman-Jouguet thermal detonation wave propagating through an initially coarse mixture of molten fuel and coolant in the course of a nuclear reactor accident is examined. The postulated mechanism is the breakup of single drops of heavy, hot liquid immersed in a vaporizable cold liquid (tin-water, or UO₂-sodium) due to passage of a shock wave, with rapid mixing and heat transfer which sustains the shock. A calculation at the required peak pressures, taking account of the interaction between the phases in a swarm of hot drops suspended initially in a comparable volume of liquid/vapor, indicates that the minimum pressures are so large as to make the probability of a steady-state thermal detonation wave due to droplet breakup and heat transfer appear to be very small in a water-cooled reactor accident, and essentially zero in an LMFBR accident.