Two-phase natural circulation flow of air and water in a reactor cavity model under an external vessel cooling during a severe accident

2006 ◽  
Vol 236 (23) ◽  
pp. 2424-2430 ◽  
Author(s):  
R.J. Park ◽  
K.S. Ha ◽  
S.B. Kim ◽  
H.D. Kim
Keyword(s):  
Natural Circulation ◽  
Severe Accident ◽  
Cavity Model ◽  
Circulation Flow ◽  
Two Phase

Two-Phase Natural Circulation Cooling Performance Assessment and Safety Analysis for APR1400 Core Catcher System

2014 ◽  
Author(s):  
Ki Won Song ◽  
Shripad T. Revankar ◽  
Hyun Sun Park ◽  
Bo Rhee ◽  
Kwang Soon Ha ◽  
...  
Keyword(s):  
Void Fraction ◽  
Flow Rate ◽  
Natural Circulation ◽  
Scaling Analysis ◽  
Circulation Flow ◽  
Two Phase ◽  
Cooling Performance ◽  
The Core ◽  
Core Catcher ◽  
Circulation Flow Rate

The two-phase natural circulation cooling performance of the APR1400 core catcher system is studied utilizing a drift flux flow model developed via scaling analysis and with an air-water experimental facility. Scaling analysis was carried out to identify key parameters, so that model facility could simulates two-phase natural circulation. In the experimental apparatus, instead of steam, air is injected into the top wall of the test channel to simulate bubble formation and void distribution due to boiling water in the core catcher channel. Measurement of void fraction critical to the heat transfer between the wall and coolant is carried out at certain key position using double-sensor conductivity probes. Results from the model provide expected natural circulation flow rate in the cooling channel of the core catcher system. The observed flow regimes and the data on void fraction are presented. For a given design of the down comer piping entrance condition bubble entrainment was observed that significantly reduced the natural circulation flow rate.

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

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Shripad T. Revankar ◽  
Kiwon Song ◽  
B. W. Rhee ◽  
R. J. Park ◽  
K. S. Ha ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Void Fraction ◽  
Natural Circulation ◽  
Rectangular Channel ◽  
Water System ◽  
Scaling Analysis ◽  
Circulation Flow ◽  
Two Phase ◽  
Decay Heat ◽  
Core Catcher

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.

Analysis of Flow Stability Boundaries of ERVC System

2013 ◽  
Author(s):  
Fei Li ◽  
Di Jin ◽  
Xiao Jing Liu ◽  
Xu Cheng
Keyword(s):  
Flow Instability ◽  
Natural Circulation ◽  
Thermal Power ◽  
Management Strategies ◽  
Density Wave ◽  
Flow Stability ◽  
Severe Accident ◽  
Two Phase ◽  
System Pressure ◽  
Calculation Results

ERVC is widely adopted as a part of in-vessel retention (IVR) in severe accident management strategies. In this paper, two-phase flow instability in natural circulation loops of external reactor vessel cooling (ERVC) system in a large size power PWR (CAP 1700 with a thermal power 5000 MWt) is simulated and evaluated by the RELAP5 code. Under certain conditions, flow instability of ERVC system are obtained. It is a kind of density wave oscillation that occurs in non-equilibrium boiling in the heat section and void flashing in the riser at low equilibrium quality and low system pressure. The calculation results show such oscillation course clearly. And several parameters affecting the flow stability are discussed.

Sign in / Sign up

Export Citation Format

Share Document