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In-core fuel freezing and plugging experiments: preliminary results of the Sandia TRAN Series I experiments

Technical Report ·
OSTI ID:6473787

The first series of TRAN experiments, described in this report, was intended to investigate the validity of current freezing models by applying them to a simple situation. The TRAN Series I experiments used pure UO/sub 2/ as the molten material, and a simple cylindrical freezing channel to simplify the analysis. Five experiments were performed at different initial channel temperatures. These experiments showed that a conduction-like fuel crust was formed for initial steel temperatures less than 973/sup 0/K, but much of the crust thickness was composed of a frozen fuel film left behind as the molten fuel slug moved up the channel. In one instance two blockages containing molten steel formed at the leading edge of the flow. Fuel penetration distances intermediate between conduction theory and bulk-freezing theory were observed. A new model embodied in the PLUGM code was developed to describe these low-temperature results. At an initial steel temperature of 1173/sup 0/K, however, rapid, massive melting of steel was observed, resulting in complex curved interfaces between the fuel and molten steel but with very little entrainment of molten steel into the fuel. Generally longer penetration distances were observed compared to previous models, and the steel-entrainment assumptions of previous models were not verified at these driving pressures; also, important finite-mass effects and liquid-film-deposition effects were inferred from the results.

Research Organization:
Sandia National Labs., Albuquerque, NM (USA); Science Applications, Inc., Albuquerque, NM (USA)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
6473787
Report Number(s):
NUREG/CR-3675; SAND-81-1726; ON: TI85003121
Country of Publication:
United States
Language:
English