[1G01-07] Nuclear Thermal Hydraulics

[1G06] Wall Friction in a 3×3 Rod Bundle under Stagnant Liquid Conditions

*Michio Murase¹, Koji Nishida¹, Toshiya Takaki¹, Shin-ichiro Kida², Ryo Kurimoto², Kosuke Hayashi², Akio Tomiyama² (1. Institute of Nuclear Safety System, Inc., 2. Kobe University)

Keywords:rod bundle, accident condition, stagnant liquid, void fraction, wall friction, uncertainty

Void fractions in rod bundles under stagnant liquid conditions have been obtained from measured pressure gradients, because wall friction is zero in one-dimensional model, but validity for the assumption of zero wall friction has not been confirmed. In our previous study, therefore, air-water experiments with a 3x3 rod bundle were carried out, void fraction and pressure gradient were measured, and it was confirmed that uncertainty to assume zero wall friction was less than 0.09 for the obtained void fraction. In this study, a correlation for the wall friction factor was obtained from the measured void fraction and pressure gradient, and the uncertainty for predicting void fraction from the measured pressure gradient decreased to 0.029 by using the obtained correlation.