Community Research and Development Information Service - CORDIS

Abstract

Ballooning of the zircaloy cladding of PWR fuel pins could occur during certain postulated Loss of Coolant Accidents (LOCA). This work concentrates on the thermohydraulic aspects of the ballooning problem using pre-formed balloon shapes attached to the rods of an electrically heated rod bundle, thereby decoupling the thermohydraulics - clad deformation interaction and avoiding nuclear heating. The rods are enclosed in a transparent silica shroud to enable photography of water droplet dynamics. The various thermohydraulic effects are investigated separately, in a unique series of tests of increasing complexity proceeding from single to two-phase conditions: isothermal air flow tests, used to infer the single phase mass flow distribution; steady state steam flow tests, used to quantify single phase heat transfer; steam and droplet tests, (dispersed flow of specified inlet conditions created by injecting water droplets into the subchannel centres with co-current steam flow); conventional reflood tests. This report presents all data obtained for an undistorted bundle and a bundle containing a centralling placed 4x4 array of balloon shapes (about 50 mm long, solid) which create a 90% subchannel blockage at their centre elevations. Reports 2 and 3 will present data on long blockages.

Additional information

Authors: FAIRBAIRN S A, CENTRAL ELECTRICITY GENERATING BOARD, BERKELEY NUCLEAR LABORATORIES, BERKELEY (UK);PIGGOTT B D G CENTRAL ELECTRICITY GENERATING BOARD, BERKELEY NUCLEAR LABORATORIES, BERKELEY (UK), CENTRAL ELECTRICITY GENERATING BOARD, BERKELEY NUCLEAR LABORATORIES, BERKELEY (UK)
Bibliographic Reference: EUR 10079 EN (1985) MF, VOL. 1, PARTS 1 AND 2, 714 P., BFR 1200, BLOW-UP COPY BFR 3570, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
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