Downcomer effects in a 1/15-scale PWR geometry-experimental data report

This report presents experimental results obtained in a 1/15-scale cylindrical model of a Pressurized water reactor (PWR) downcomer region at pressures up to 75 psia. These tests are part of a continuing effort to develop analytical tools and predictive techniques to permit calculation of lower plenum filling rates, as a function of time, during a postulated Loss-of-Coolant Accident (LOCA) in PWRs. The effects of countercurrent flow, lower plenum voiding, cold leg steam, and superheated downcomer walls were investigated separately and in combination under test conditions which included elevated vessel pressure, transient steam mass flows (and transient vessel pressure), and coupling of reverse core and cold leg steam flows. A range of geometric and hydraulic parameters was tested including two annulus gap sizes (0.5 and 1.0 inch), a scaled and a deep lower plenum, various ECC water temperatures from 70-212F, ECC water flow rates from 2-180 gpm, and others.