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ISSN Online: 2377-424X

ISBN Print: 0-89116-299-2

International Heat Transfer Conference 7
September, 6-10, 1982, Munich, Germany

CONTROLLED TRANSIENT CHF TESTS IN A 5×5 ROD BUNDLE UNDER LOSS-OF-COOLANT ACCIDENT CONDITIONS

Get access (open in a dialog) DOI: 10.1615/IHTC7.3590
pages 505-509

要約

To develop transient critical heat flux (CHF) correlations that are applicable to pressurized water reactor (PWR) loss-of-coolant accident (LOCA) conditions, it is necessary to develop a data base in a geometry representative of a PWR over the range of fluid conditions expected to occur. A testing program for obtaining such data has been completed in a 5×5 square rod bundle with a heated length of 3.66m using water as a coolant.

The bundle design was typical of 15×15 type PWR fuel with 1.07-cm diameter rods separated at a 1.43 cm pitch by six egg-crate type spacer grids. The axial power profile was a chopped cosine yielding a 1.66 peak-to-average heat flux ratio.

Single parameter variation tests were run from a base set of conditions representative of steady-state PWR operation. The parameter variations discussed are the flow decay rate, 10 to 100 percent per second, and flow direction.

The tests were performed by controlling fluid conditions, (flow, pressure, and enthalpy) at the test section inlet as a function of time while maintaining constant power. The cladding temperature response was measured at 12 axial positions on each heater rod (a total of 300 instrumented locations in the bundle).

The results show that the time of CHF becomes less dependent on inlet condition for fast flow decay rates. Effects of grids on CHF inception and propagation were noted in all tests. The mass velocity required to prevent CHF was higher for downflow than upflow for the slow (10%/sec) flow decay tests.