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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

FLOW BLOCKAGE EFFECTS ON REFLOOD HEAT TRANSFER IN 25-ROD BUNDLES

Get access (open in a dialog) DOI: 10.1615/IHTC7.3540
pages 475-479

Sinopsis

The effect of flow blockages in PWR fuel rod bundles on the effectiveness of cooling during reflood phase of a LOCA is important for the safety analysis. Within the FEBA-program, to date, four test series have been evaluated on a comparative basis. Separate effect tests with an electrically heated 5×5 bundle of full length rods have been performed to investigate the influence of different flow obstacles.
The experimental results indicate that partial blockages of coolant subchannels, even up to 90 %, do not significantly diminish the cooling in the wake of such severe obstacles. Only over a certain axial length the peak cladding temperature is increased by up to 50 K for the 90 % blockage. However, for a 62 % blockage, cladding temperatures decrease or remain unaltered compared with the temperatures in the bypass region of the blockage. Cladding temperatures at the beginning of quenching and the quench times are definitely affected. The heat removal from both blockages is delayed inspite of the low temperatures of the "lifted" claddings.