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Title: Development of liquid-film tracking models for analysis of AP-600 passive containment cooling system

Abstract

The AP-600, an advanced pressurized water reactor, utilizes a passive containment cooling system (PCCS) to remove heat released inside the containment vessel following postulated design-base accidents (DBAS) such as a main-steam-line break or loss-of-coolant accident. The containment vessel consists of a vertical cylindrical shell and is capped at both top and bottom by a dome that is also a body of revolution with a meridian cross section in the shape of a semiellipse with a horizontal major axis. During a DBA, heat released to the interior of the steel containment vessel is removed by evaporation of a continuously flowing thin liquid film on the outside surface of the vessel, thus lowering the temperature of the steel vessel wall so that steam condenses on its inside surface. The external liquid film is formed by flooding water at top of the ellipsoidal dome. Evaporation of the falling liquid film is enhanced by buoyancy-driven flows of moist air in an annular space outside the steel containment vessel. To ensure PCCS performance, it is necessary to predict both the evaporating film on the outside surface of the vessel and the condensate film on its inside. To this end, two liquid-film tracking models for time-dependentmore » flows (a simplified model and a comprehensive model) have been developed and implemented in the COMMIX code. COMMIX is a general-purpose, time-dependent, multidimensional computer code for thermal hydraulic analysis of single- or multicomponent engineering systems. It solves a system of conservation equations of continuities for up to six species, mixture momentum, and mixture energy, and a k-{epsilon} two-equation turbulent model. A unique feature of the COMMIX code is its porous-media formulation, which represents the first unified approach to thermal-hydraulic analysis. The tracking models discussed in this report compute the liquid-film thickness, its mean velocity, and its temperature on both sides of the steel containment vessel.« less

Authors:
;  [1];  [2]
+ Show Author Affiliations
  1. Argonne National Lab., IL (United States)
  2. Nuclear Regulatory Commission, Washington, DC (United States)
Publication Date:
Research Org.:
Argonne National Lab., IL (United States)
Sponsoring Org.:
Nuclear Regulatory Commission, Washington, DC (United States)
OSTI Identifier:
10188828
Report Number(s):
ANL/MCT/CP-78784
ON: DE94001339; TRN: 93:024098
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1993
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 22 GENERAL STUDIES OF NUCLEAR REACTORS; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; PWR TYPE REACTORS; REACTOR COOLING SYSTEMS; CONTAINMENT SYSTEMS; FILMS; FLUID FLOW; HEAT TRANSFER; HYDRAULICS; REACTOR SAFETY; LOSS OF COOLANT; CONDENSATES; EVAPORATION; BOUNDARY CONDITIONS; C CODES; MATHEMATICAL MODELS; 210200; 220900; 990200; POWER REACTORS, NONBREEDING, LIGHT-WATER MODERATED, NONBOILING WATER COOLED; MATHEMATICS AND COMPUTERS

Citation Formats

Sun, J.G., Sha, W.T., and Chen, Y.S. Development of liquid-film tracking models for analysis of AP-600 passive containment cooling system. United States: N. p., 1993. Web. doi:10.2172/10188828.
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Sun, J.G., Sha, W.T., & Chen, Y.S. Development of liquid-film tracking models for analysis of AP-600 passive containment cooling system. United States. doi:10.2172/10188828.
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Sun, J.G., Sha, W.T., and Chen, Y.S. Fri . "Development of liquid-film tracking models for analysis of AP-600 passive containment cooling system". United States. doi:10.2172/10188828. https://www.osti.gov/servlets/purl/10188828.
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@article{osti_10188828,
title = {Development of liquid-film tracking models for analysis of AP-600 passive containment cooling system},
author = {Sun, J.G. and Sha, W.T. and Chen, Y.S.},
abstractNote = {The AP-600, an advanced pressurized water reactor, utilizes a passive containment cooling system (PCCS) to remove heat released inside the containment vessel following postulated design-base accidents (DBAS) such as a main-steam-line break or loss-of-coolant accident. The containment vessel consists of a vertical cylindrical shell and is capped at both top and bottom by a dome that is also a body of revolution with a meridian cross section in the shape of a semiellipse with a horizontal major axis. During a DBA, heat released to the interior of the steel containment vessel is removed by evaporation of a continuously flowing thin liquid film on the outside surface of the vessel, thus lowering the temperature of the steel vessel wall so that steam condenses on its inside surface. The external liquid film is formed by flooding water at top of the ellipsoidal dome. Evaporation of the falling liquid film is enhanced by buoyancy-driven flows of moist air in an annular space outside the steel containment vessel. To ensure PCCS performance, it is necessary to predict both the evaporating film on the outside surface of the vessel and the condensate film on its inside. To this end, two liquid-film tracking models for time-dependent flows (a simplified model and a comprehensive model) have been developed and implemented in the COMMIX code. COMMIX is a general-purpose, time-dependent, multidimensional computer code for thermal hydraulic analysis of single- or multicomponent engineering systems. It solves a system of conservation equations of continuities for up to six species, mixture momentum, and mixture energy, and a k-{epsilon} two-equation turbulent model. A unique feature of the COMMIX code is its porous-media formulation, which represents the first unified approach to thermal-hydraulic analysis. The tracking models discussed in this report compute the liquid-film thickness, its mean velocity, and its temperature on both sides of the steel containment vessel.},
doi = {10.2172/10188828},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Oct 01 00:00:00 EDT 1993},
month = {Fri Oct 01 00:00:00 EDT 1993}
}
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Technical Report:
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DOI:  10.2172/10188828
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  • ; ; ; ...
    COMMIX modeling and basic concepts that relate components, i.e., containment, water film cooling, and natural draft air flow systems. of the AP-600 Passive Containment Cooling System are discussed. The critical safety issues during a postulated accident have been identified as (1) maintaining the liquid film outside the steel containment vessel, (2) ensuring the natural convection in the air annulus. and (3) quantifying both heat and mass transfer accurately for the system. The lack of appropriate heat and mass transfer models in the present analysis is addressed. and additional assessment and validation of the proposed models is proposed.

  • ; ; ; ...
    One unique feature of the AP-600 is its passive containment cooling system (PCCS), which is designed to maintain containment pressure below the design limit for 72 hours without action by the reactor operator. During a design-basis accident, i.e., either a loss-of-coolant or a main steam-line break accident, steam escapes and comes in contact with the much cooler containment vessel wall. Heat is transferred to the inside surface of the steel containment wall by convection and condensation of steam and through the containment steel wall by conduction. Heat is then transferred from the outside of the containment surface by heating andmore » evaporation of a thin liquid film that is formed by applying water at the top of the containment vessel dome. Air in the annual space is heated by both convection and injection of steam from the evaporating liquid film. The heated air and vapor rise as a result of natural circulation and exit the shield building through the outlets above the containment shell. All of the analytical models that are developed for and used in the COMMIX-ID code for predicting performance of the PCCS will be described. These models cover governing conservation equations for multicomponents single phase flow, transport equations for the {kappa}-{epsilon} two-equation turbulence model, auxiliary equations, liquid-film tracking model for both inside (condensate) and outside (evaporating liquid film) surfaces of the containment vessel wall, thermal coupling between flow domains inside and outside the containment vessel, and heat and mass transfer models. Various key parameters of the COMMIX-ID results and corresponding AP-600 PCCS experimental data are compared and the agreement is good. Significant findings from this study are summarized.« less

  • ; ; ; ...
    COMMIX modeling and basic concepts that relate components, i.e., containment, water film cooling, and natural draft air flow systems. of the AP-600 Passive Containment Cooling System are discussed. The critical safety issues during a postulated accident have been identified as (1) maintaining the liquid film outside the steel containment vessel, (2) ensuring the natural convection in the air annulus. and (3) quantifying both heat and mass transfer accurately for the system. The lack of appropriate heat and mass transfer models in the present analysis is addressed. and additional assessment and validation of the proposed models is proposed.

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