Experimental and theoretical investigation of melt propagation in rubble beds for application in severe-accident analyses

Conference · Fri Jan 01 04:00:00 EST 1988 · Trans. Am. Nucl. Soc.; (United States)

OSTI ID:5862182

Ahmed, E K.S.; Podowski, M Z; Lahey, R Jr

One of the consequences of core heatup and degradation during severe accidents is the formation of a rubblized bed, composed of various materials and particles of different size. As a result of continuous heatup due to the decay heat generation augmented by oxidation reaction, individual materials reach their melting temperatures, liquefy, and relocate downward to cooler core regions. Whereas the relocation of most of the low-melting temperature materials occurs very quickly, the melting process of ZrO/sub 2/ and UO/sub 2/, their relocation, and interaction with solid debris particles is relatively slow. In particular, the release of molten fuel from the corium may be delayed due to the formation of a solid crust separating the molten fuel above from the lower reactor sections. Needless to say, the time history of fuel melting and release may have a profound effect on the overall accident consequences. The purpose of this paper is to present the results of experimental simulation and analytical/numerical analysis of the interaction between a rubble bed and a penetrating (and partially freezing) liquid. In the experiments, two different materials were used to stimulate a rubble bed consisting of spherical particles, i.e., paraffin and glass. The bed was subjected to molten paraffin droplets, injected from the top. The droplets were partially freezing when flowing through the bed. The combined melt relocation and solidification processes were studied parametrically, including the effect of such parameters as, bed porosity, melt temperature, relative subcooling of solid particles, velocity, and mass flow rate.

• OSTI ID: 5862182
• Report Number(s): CONF-881011-
• Conference Information: Journal Name: Trans. Am. Nucl. Soc.; (United States) Journal Volume: 57
• Country of Publication: United States
• Language: English

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