Pressure Load Estimation During Ex-Vessel Steam Explosion

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Matjaž Leskovar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Phase 1 ◽  
Interaction Process ◽  
Radioactive Material ◽  
Primary System ◽  
Pressurized Water Reactor ◽  
Reactor Accident ◽  
Pressurized Water ◽  
Water Reactor

An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor pressure vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel-coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In the article, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which is being developed for the simulation of fuel-coolant interactions. A comprehensive parametric study was performed by varying the location of the melt release (central and side melt pours), the cavity water subcooling, the primary system overpressure at vessel failure, and the triggering time for explosion calculations. The main purpose of the study was to determine the most challenging ex-vessel steam explosion cases in a typical pressurized water reactor and to estimate the expected pressure loadings on the cavity walls. Special attention was given to melt droplet freezing, which may significantly influence the outcome of the fuel-coolant interaction process. The performed analysis shows that for some ex-vessel steam explosion scenarios much higher pressure loads are predicted than obtained in the OECD program SERENA Phase 1.

Estimation of Pressure Loads During Ex-Vessel Steam Explosion

2008 ◽  
Author(s):  
Matjazˇ Leskovar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Phase 1 ◽  
Interaction Process ◽  
Radioactive Material ◽  
Primary System ◽  
Pressurized Water Reactor ◽  
Reactor Accident ◽  
Pressurized Water ◽  
Water Reactor

An ex-vessel steam explosion may occur when, during a severe reactor accident, the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles that may endanger surrounding structures. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. In the paper, different scenarios of ex-vessel steam explosions in a typical pressurized water reactor cavity are analyzed with the code MC3D, which is being developed for the simulation of fuel-coolant interactions. A comprehensive parametric study was performed varying the location of the melt release (central and side melt pours), the cavity water sub-cooling, the primary system overpressure at vessel failure and the triggering time for explosion calculations. The main purpose of the study was to determine the most challenging ex-vessel steam explosion cases in a typical pressurized water reactor and to estimate the expected pressure loadings on the cavity walls. Special attention was given to melt droplets freezing, which may significantly influence the outcome of the fuel-coolant interaction process. The performed analysis shows that for some ex-vessel steam explosion scenarios much higher pressure loads are predicted than obtained in the OECD program SERENA Phase 1.

Simulation of Steam Explosion with a General Purpose CFD Code

2006 ◽  
Author(s):  
Matjazˇ Leskovar ◽  
Bosˇtjan Koncˇar
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
General Purpose ◽  
Reactor Accident ◽  
Pressure Relief ◽  
Pressurized Water ◽  
Explosion Pressure ◽  
Flow Conservation

An ex-vessel steam explosion may occur when during a severe reactor accident the reactor vessel fails and the molten core pours into the water in the reactor cavity. A steam explosion is a fuel coolant interaction process where the heat transfer from the melt to water is so intense and rapid that the timescale for heat transfer is shorter than the timescale for pressure relief. This can lead to the formation of shock waves and production of missiles at later times, during the expansion of the highly pressurized water vapor, that may endanger surrounding structures. In contrast to specialized steam explosion CFD codes, where the steam explosion is modeled on micro-scale using fundamental averaged multiphase flow conservation equations, in the presented approach the steam explosion is modeled in a simplified manner as an expanding high-pressure premixture of dispersed molten fuel, liquid water and vapor. Applying the developed steam explosion model, a comprehensive analysis of the ex-vessel steam explosion in a typical PWR reactor cavity was done using the CFD code CFX-10. At four selected locations, which are of importance for the assessment of the vulnerability of cavity structures, the pressure histories were recorded and the corresponding pressure impulses calculated. The pressure impulses determine the destructive potential of the steam explosion and represent the input for the structural mechanical analysis of the cavity structures. The simulation results show that the pressure impulses depend mainly on the steam explosion energy conversion ratio, whereas the influence of the premixture vapor volume fraction, which is a parameter in our model and determines the maximum steam explosion pressure, is not significant.

scholarly journals Transformation of Pressurized Water Reactor (AP1000) to Fuzzy Graph

MATEMATIKA ◽  
2018 ◽  
Vol 34 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Azmirul Ashaari ◽  
Tahir Ahmad ◽  
Wan Munirah Wan Mohamad
Keyword(s):  
Nuclear Power ◽  
Ph Value ◽  
Published Data ◽  
Primary System ◽  
Fuzzy Graph ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Fission Process ◽  
Water Reactor ◽  
Dynamic Concentration

Pressurized water reactor (PWR) type AP1000 is a third generation of a nuclear power plant. The primary system of PWR using uranium dioxide to generate heat energy via fission process. The process influences temperature, pressure and pH value of water chemistry of the PWR. The aim of this paper is to transform the primary system of PWR using fuzzy autocatalytic set (FACS). In this work, the background of primary system of PWR and the properties of the model are provided. The simulation result, namely dynamic concentration of PWR is verified against published data.

In-Vessel Corium Behavior and Steam Explosion Risks: A Review of Experimental Approaches

2017 ◽  
Author(s):  
Pei Shen ◽  
Wenzhong Zhou
Keyword(s):  
Heat Transfer ◽  
Steam Explosion ◽  
Large Scale ◽  
Nuclear Reactor ◽  
Reactor Core ◽  
Reactor Vessel ◽  
Radioactive Material ◽  
Severe Accident ◽  
Reactor Accident ◽  
Experimental Approaches

Although no one would like to see, a severe nuclear reactor accident may result in reactor core melting, the fuel melt dropping into water in the reactor vessel, and then interacting with coolant into steam explosion. Steam explosion is a result of very rapid and intense heat transfer and violent interaction between the high temperature melt and low temperature coolant. The timescale for heat transfer is shorter than that for pressure relief, resulting in the formation of shock waves and/or the production of missiles at a later time during the expansion of coolant steam explosion. Steam explosion may endanger the reactor vessel and surrounding structures. During a severe reactor accident scenario, steam explosion is an important risk, even though its probability to occur is pretty low, since it could lead to large releases of radioactive material, and destroy the containment integrity. This study provides a comprehensive review of vapor explosion experiments, especially the most recent ones. In this review, fist, small to intermediate scale experiments related to premixing, triggering and propagation stages are reviewed and summarized in tables. Then the intermediate to large scale experiments using prototypic melt are reviewed and summarized. The recent OECD/SERENA2 project including KROTOS and TROI facilities’ work is also discussed. The studies on steam explosion are vital for reactor severe accident management, and will lead to improved reactor safety.

Analysis of the dynamic pressure from ex-vessel steam explosion for pressurized water reactor

2017 ◽  
Vol 100 ◽  
pp. 266-275 ◽  
Author(s):  
Ronghua Chen ◽  
Chenxi Li ◽  
Jun Wang ◽  
G.H. Su ◽  
Suizheng Qiu ◽  
...  
Keyword(s):  
Steam Explosion ◽  
Dynamic Pressure ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

Heat Transfer in Pressurized Water Reactor Components Most Often Subject to Thermal Shock

1980 ◽  
Vol 47 (1) ◽  
pp. 125-152 ◽  
Author(s):  
F. Parras ◽  
M. Bosser ◽  
D. Milan ◽  
G. Berthollon
Keyword(s):  
Heat Transfer ◽  
Thermal Shock ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor
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