An experimental investigation of multimode heat transfer within a horizontal spent nuclear fuel assembly
- Univ. of Texas, Austin, TX (United States). Dept. of Mechanical Engineering
Combined natural convection and radiative heat transfer has been experimentally investigated in an enclosed horizontal rod bundle, which simulates a spent nuclear fuel assembly under dry storage and/or transport conditions. The objective of this 2-D experimental study was to assess the relative contributions of conduction, convection, and radiation heat transfer with regard to the overall assembly heat transfer and to individually quantify these mechanisms under a broad range of representative environments. The resulting data consist of: (1) measured temperatures within the assembly as a function of power, pressure, and backfill gas; (2) the relative radiative contribution as a function of power, pressure, and backfill gas; (3) correlations of convective Nusselt number as a function of Rayleigh number for individual rods within the array; and (4) correlations of array averaged Nusselt number as a function of array averaged Rayleigh number. On an individual rod basis, the data indicate that convection is dominant for rods located in the lower regions of the rod bundle, while radiation becomes increasingly important for rods at the top of the bundle. As a result, Nusselt numbers tend to decrease as one considers rod positions progressively higher in the enclosed array. Furthermore, there is evidence that individual rods within the array are in different but co-existing flow regimes at a given power/pressure statepoint. For the rod bundle as a whole, the bundle averaged data suggest the presence of a semi-conductive and convective regime. Natural convection is deemed a significant heat transfer mechanism in this geometry, subject to nitrogen or air backfills. Helium backfills remain in a conduction regime.
- OSTI ID:
- 435657
- Report Number(s):
- CONF-951135--; ISBN 0-7918-1751-2
- Country of Publication:
- United States
- Language:
- English
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