A new theory of a propagating trigger of steam explosions
- Georgia Institute of Technology, Atlanta (USA)
An energetic steam explosion may occur if a hot molten material, e.g., molten core in the case of a nuclear reactor severe accident, is dropped in water. The explosive heat transfer and vapor production is attributed to the dramatic increase of the melt/coolant contact area due to fine melt fragmentation. The propagation of the interaction has been explained by Board et al. in the framework of the steady detonation theory in analogy to chemical high explosives. According to the new proposed theory, during the premixing stage of the explosion, a layer of the liquid coolant acquires a high degree of superheat due to the lack of nucleation sites characteristic of liquid-liquid contact. Given a small triggering disturbance, nucleation occurs and escalates in the superheated coolant. The shock-induced nucleation (SIN) drives a detonation wave of sufficient strength to destabilize film boiling and results in direct liquid-liquid contact of sufficient duration to induce fragmentation by some thermal mechanism. The rather weak SIN wave is not responsible for the destructive potential of a steam explosion; it merely acts as a propagating trigger. The slower fragmentation thus occurs behind the trigger wave in a layer of an ever-increasing thickness. Thus, the coherence of the interaction depends on the inertial confinement of the interaction zone - an experimentally-acknowledged fact (e.g., Sandia National Laboratories (SNL) rigid confinement test)-and the interaction in a way resembles that occurring in low explosives like gunpowder rather than high explosives. If this theory is correct, interesting practical implications on the research efforts to control steam explosions may follow.
- OSTI ID:
- 5702325
- Report Number(s):
- CONF-901101--
- Journal Information:
- Transactions of the American Nuclear Society; (USA), Journal Name: Transactions of the American Nuclear Society; (USA) Vol. 62; ISSN TANSA; ISSN 0003-018X
- Country of Publication:
- United States
- Language:
- English
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STEAM
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