Experimental studies of the effect of flow restrictions in a small rod bundle under emergency core coolant injection conditions

AbstractA nine-pin array of electrical heaters was used to study the effects of partial flow blockage on the capability of cooling the array through injection of water under simulated reactor decay heat power conditions. The array was placed in a transparent tube and tests were conducted with six different blockage configurations.Tests were conducted by slowly heating the array until the temperature at the midelevation of the center pin was 1100°F. Full power (1 kW/ft) was then applied, until a midelevation temperature of either 1600 or 1800°F was reached. Bottom flooding was then initiated at a flow rate of 2 in./sec. Tests were conducted at both temperatures for each configuration. Temperatures were recorded at selected locations on one row of three heaters and high-speed motion pictures were taken.These tests, conducted for a variety of blockage geometries, demonstrated that severe flow blockage of a small fuel pin array does not result in significant reduction in the effectiveness of cooling the array by emergency cooling flooding.