STUDIES RELATING TO THE REACTION BETWEEN ZIRCONIUM AND WATER AT HIGH TEMPERATURES

controlled by the parabolic rate law, resulting in rapid cooling of the particles. A mathematical model of the reaction of molten metal spheres with water was proposed. Explosive reactions were found to occur with particles smaller than about 1 mm in heated water and 0.5 mm in room-temperature water. The explosive reactions were caused by the ability of the evolving H/sub 2/ to propel the particles through water at high speed. The high-speed motion was detected on motion picture film and had the effect of removing the gaseous diffusion barrier (increasing the Nusselt number), resulting in very rapid reaction. Computed results compared favorably with experimental results obtained by the condenser- discharge experiment and with the results of previous investigators. Computations indicated that the extent and rate of reaction depended on the particle diameter and the water temperature, and were relatively independent of the metal temperature so long as the metal was fully melted. This makes it possible to estimate the extent of Zr-water reaction that would occur during a reactor accident in which the particle sizes of the residue could be estimated. Comparisons were made with the results of meltdown experiments in TREAT, and applications to reactor hazards analysis were discussed. (auth)