Cold leg ECC flow oscillations. Topical report

Flow and pressure oscillations were analyzed and investigated experimentally in scale models of PWR cold legs. The analysis predicted data obtained in experimental cold leg models varying in (diameter) scale from 1/20 to 1/3, at sub-cooling temperatures from 10 to 200F, at injection angles from 45 degrees to 90 degrees, at downstream lengths from (L sub d)/D = 15 to 120, at system pressures from 1 to 4 atm., with various boundary conditions, and over a significant range of steam and water flow rates. The analysis is able, in most cases, to predict the general features of the oscillatory behavior, such as the presence or absence of flow oscillations and the oscillatory frequencies. It fails, in some cases, to predict specific oscillatory characteristics such as pressure amplitudes or the trend of frequency as a function of water flow rate