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Investigation of natural convection in a volumetrically heated spherical cavity with simultaneous freezing on the cavity wall

Book ·
OSTI ID:458423
;  [1]
  1. Univ. of California, Los Angeles, CA (United States)

One strategy for preventing the melting of a nuclear reactor vessel is to flood the concrete cavity with subcooled water in accidents in which relocation of core material into the vessel lower head occurs. After the core material relocated into the vessel, a crust of solid material forms on the inner wall of the vessel, however, most of the pool remains molten and natural convection exists in the pool. In the present work, experiments were conducted to examine natural convection heat transfer in internally heated spherical cavities with external cooling in the presence of the crust. In the experiments, R-113 contained in a Pyrex bell jar was used as a test liquid and the vessel was cooled from the outside with liquid nitrogen. In the experiments R-113 froze on the vessel wall and formed a crust along the wall. The pool was volumetrically heated using a 2000 Watt magnetron taken from a conventional microwave oven. A series of chromel alumel thermocouples was used to measure the pool and the wall temperatures at different locations. In the experiments, pool depth and Rayleigh numbers were varied parametrically. Both local and average heat transfer coefficients based on maximum pool temperature were obtained. The crust thickness was measured and the heat transfer coefficients based on the crust thickness were also calculated. The results have been compared with the correlations obtained for experiments conducted in the absence of the crust.

OSTI ID:
458423
Report Number(s):
CONF-951135--; ISBN 0-7918-1751-2
Country of Publication:
United States
Language:
English