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Prediction of Countercurrent Flow Limitation and Its Uncertainty in Horizontal and Slightly Inclined Pipes

Michio Murase, Yoichi Utanohara, Takayoshi Kusunoki, Yasunori Yamamoto, Dirk Lucas, Akio Tomiyama

Nuclear Technology / Volume 197 / Number 2 / February 2017 / Pages 140-157

Technical Paper / dx.doi.org/10.13182/NT16-96

First Online Publication:January 16, 2017
Updated:February 16, 2017

We proposed prediction methods for countercurrent flow limitation (CCFL) in horizontal and slightly inclined pipes with one-dimensional (1-D) computations and uncertainty of computed CCFL. In this study, we applied the proposed methods to a full-scale pressurizer surge line [inclination angle θ = 0.6 deg, diameter D = 300 mm, and ratio of the length to the diameter (L/D) = 63] in a specific pressurized water reactor, performed 1-D computations and three-dimensional (3-D) numerical simulations, and found that uncertainties caused by effects of the diameter and fluid properties on CCFL were small. We also applied the proposed methods to experiments for hot-leg and surge line models (θ = 0 and 0.6 deg, D = 0.03 to 0.65 m, and L/D = 4.5 to 63) to generalize them, performed 1-D computations, and found that uncertainties caused by effects of θ and L on CCFL were large due to the setting error for θ and differences among experiments. This shows that a small-scale air-water experiment with the same θ and L/D as those in an actual plant is effective to reduce the uncertainty of CCFL prediction.

 
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