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Research Papers

Prediction Method of Countercurrent Flow Limitation in a Pressurizer Surge Line and Its Evaluation for a 1/10-Scale Model

[+] Author and Article Information
Michio Murase

Mem. ASME
Institute of Nuclear Safety System, Inc.,
64 Sata, Mihama-cho, Mikata-gun,
Fukui 919-1205, Japan
e-mail: murase@inss.co.jp

Yoichi Utanohara

Institute of Nuclear Safety System, Inc.,
64 Sata, Mihama-cho, Mikata-gun,
Fukui 919-1205, Japan
e-mail: utanohara@inss.co.jp

Takayoshi Kusunoki

Institute of Nuclear Safety System, Inc.,
64 Sata, Mihama-cho, Mikata-gun,
Fukui 919-1205, Japan
e-mail: kusunoki.takayoshi@inss.co.jp

Dirk Lucas

Helmholtz-Zentrum Dresden-Rossendorf,
P.O. Box 510 119, Dresden 01314, Germany
e-mail: d.lucas@hzdr.de

Akio Tomiyama

Kobe University,
Hyogo 657-8501, Japan
e-mail: tomiyama@mech.kobe-u.ac.jp

1Corresponding author.

Manuscript received July 16, 2015; final manuscript received May 10, 2016; published online June 17, 2016. Editor: Igor Pioro.

ASME J of Nuclear Rad Sci 2(3), 031021 (Jun 17, 2016) (9 pages) Paper No: NERS-15-1164; doi: 10.1115/1.4033629 History: Received July 16, 2015; Accepted May 10, 2016

Abstract

The method for predicting countercurrent flow limitation (CCFL) and its uncertainty in an actual pressurizer surge line of a pressurized water reactor (PWR) using 1/10-scale air–water experimental data, one-dimensional (1D) computations, and three-dimensional (3D) numerical simulations was proposed. As one step of the prediction method, 3D numerical simulations were carried out for countercurrent air–water flows in a 1/10-scale model of the pressurizer surge line to evaluate capability of the 3D simulation method and decide uncertainty of CCFL characteristics evaluated for the 1/10-scale model. The model consisted of a vertical pipe, a vertical elbow, and a slightly inclined pipe with elbows. In the actual 1/10-scale experiment, air supplied into the lower tank flowed upward to the upper tank and water supplied into the upper tank gravitationally flowed downward to the lower tank through the pressurizer surge line. In the 3D simulation, however, water was supplied from the wall surface of the vertical pipe to avoid effects of flooding at the upper end (the 3D simulation largely underestimated falling water flow rates at the upper end). Then, the flow pattern in the slightly inclined pipe was successfully reproduced, and the simulated CCFL values for the inclination angle of $θ=0.6 deg$ (slope of 1/100) agreed well with the experimental CCFL data. The uncertainty among air–water experiments, 1D computations, and 3D simulations for the 1/10-scale model was $dC=±0.015$ for the CCFL constant of $C=0.50$. The effects of $θ$ ($θ=0,1.0$ deg) on CCFL characteristics were simulated and discussed.

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Figures

Fig. 1

Experimental setup for the 1/10-scale model of a pressurizer surge line [12]

Fig. 2

Computational grid for the experimental setup shown in Fig. 1

Fig. 3

Flow pattern simulated with water supply into the upper tank (θ=0.6  deg, JG=3.0  m/s)

Fig. 4

Observed and simulated flow patterns (θ=0.6  deg). (a) Observed at JG=3.8  m/s [12]. (b) Simulated at JG=3.0  m/s (water supply from the vertical pipe)

Fig. 5

Changes of simulated water mass in the lower tank at θ=0.6  deg (one plot for 100 time steps). (a) Water mass in the lower tank. (b) Water flow rate into the lower tank

Fig. 6

CCFL characteristics (θ=0.6  deg)

Fig. 7

Changes of simulated water mass in the lower tank at θ=0 and 1.0 deg

Fig. 8

Effects of inclination angle on CCFL characteristics

Fig. 9

Comparison of CCFL characteristics (1D: 1D computation, 3D: 3D simulation, dC: uncertainty of CCFL constant)

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