Research Papers

Study of Two-Phase Natural Circulation Cooling of Core Catcher System Using Scaled Model

[+] Author and Article Information
Shripad T. Revankar

Fellow ASME
School of Nuclear Engineering,
Purdue University and Pohang
University of Science and Technology,
400 Central Drive,
West Lafayette, IN 47906
e-mail: shripad@purdue.edu

Kiwon Song

Pohang University of Science and Technology,
Pohang, Gyeongbuk 790-784, South Korea
e-mail: k1song@postech.ac.kr

B. W. Rhee

Korean Atomic Energy Research Institute,
Daejeon, Yuseong-gu 305-353, South Korea
e-mail: bwrhee@kaeri.re.kr

R. J. Park

Korean Atomic Energy Research Institute,
Daejeon, Yuseong-gu 305-353, South Korea
e-mail: rjpark@kaeri.re.kr

K. S. Ha

Korean Atomic Energy Research Institute,
Daejeon, Yuseong-gu 305-353, South Korea
e-mail: tomo@kaeri.re.kr

J. H. Song

Korean Atomic Energy Research Institute,
Daejeon, Yuseong-gu 305-353, South Korea
e-mail: dosa@kaeri.re.kr

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received June 29, 2014; final manuscript received January 12, 2015; published online April 15, 2015. Assoc. Editor: Suman Chakraborty.

J. Thermal Sci. Eng. Appl 7(3), 031006 (Sep 01, 2015) (9 pages) Paper No: TSEA-14-1154; doi: 10.1115/1.4030249 History: Received June 29, 2014; Revised January 12, 2015; Online April 15, 2015

A two-phase natural circulation cooling has been proposed to remove melted core decay heat by external core catcher cooling system during sever accident scenario. In this paper, two types of the core catcher cooling loops, one with heated loop and the other adiabatic loop simulated with air water system are analytically studied. First, a scaling analysis was carried out for natural circulation flow in a closed loop. Based on the scaling analyses, simulation of two-phase natural circulation is carried out both for air–water and steam–water system in an inclined rectangular channel. The heat flux corresponding to the decay heat is simulated with steam generation rate or air flux into the test section to produce equivalent flow quality and void fraction. Design calculations were carried out for typical core catcher design to estimate the expected natural circulation rates. The natural circulation flow rate and two-phase pressure drop were obtained for different heat inputs or equivalent air injection rates expressed as void fraction for a select downcomer pipe size. These results can be used to scale a steam water system using scaling consideration presented. The results indicate that the air–water and steam water system show similar flow and pressure drop behavior.

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Fig. 1

Core catcher concept with natural circulation cooling with two-phase flow under core plate and return circulation through downcomer

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Fig. 2

Schematic of air–water simulation loop

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Fig. 3

The interpolations in terms of the inclined angle and length

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Fig. 4

Natural circulation flow rate calculation

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Fig. 5

(a) Natural circulation mass flow rate and (b) mass flux as function of heat load in the prototype and steam–water model loop

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Fig. 6

The exit void fraction as function of heat load in the prototype and air–water model loop

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Fig. 7

(a) Total loop pressure drop and (b) two-phase pressure drop at different heat loads

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Fig. 8

(a) Single-phase, two-phase, and total pressure drop and (b) the liquid velocity in downcomer pipe as a function of exit void fraction for model loop with 7.6 cm diameter downcomer

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Fig. 9

Comparison of exit void fraction predicted using homogeneous model and drift-flux model in the model facility with 7.6 cm downcomer pipe

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Fig. 10

Comparison of natural circulation mass flux predicted using homogeneous model and drift-flux model in the model facility with 7.6 cm downcomer pipe

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Fig. 11

Single-phase, two-phase, and total pressure drop (kPa) against nondimensional heat load

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Fig. 12

Slip ratios between gas and liquid phase at inclined and vertical section of the cooling channel as function of heat

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Fig. 13

Natural circulation flow rates in a model test loop with air–water and steam–water system




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