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Title: Experimental investigations of uncovered-bundle heat transfer and two-phase mixture-level swell under high-pressure low heat-flux conditions. [PWR]

Technical Report ·
DOI:https://doi.org/10.2172/5274335· OSTI ID:5274335

Results are reported from a series of uncovered-bundle heat transfer and mixture-level swell tests. Experimental testing was performed at Oak Ridge National Laboratory in the Thermal Hydraulic Test Facility (THTF). The THTF is an electrically heated bundle test loop configured to produce conditions similar to those in a small-break loss-of-coolant accident. The objective of heat transfer testing was to acquire heat transfer coefficients and fluid conditions in a partially uncovered bundle. Testing was performed in a quasi-steady-state mode with the heated core 30 to 40% uncovered. Linear heat rates varied from 0.32 to 2.22 kW/m.rod (0.1 to 0.68 kW/ft.rod). Under these conditions peak clad temperatures in excess of 1050 K (1430/sup 0/F) were observed, and total heat transfer coefficients ranged from 0.0045 to 0.037 W/cm/sup 2/.K (8 to 65 Btu/h.ft/sup 2/./sup 0/F). Spacer grids were observed to enhance heat transfer at, and downstream of, the grid. Radiation heat transfer was calculated to account for as much as 65% of total heat transfer in low-flow tests.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
5274335
Report Number(s):
NUREG/CR-2456; ORNL-5848; ON: DE82013357; TRN: 82-013449
Resource Relation:
Other Information: Portions of document are illegible
Country of Publication:
United States
Language:
English