Massively Parallelized Simulation of Deflagration-to-Detonation Transition in a Konvoi-Type Pressurized Water Reactor

2016 ◽  
Author(s):  
Josef Hasslberger ◽  
Peter Katzy ◽  
Thomas Sattelmayer ◽  
Lorenz R. Boeck
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Combustion Process ◽  
Three Dimensional ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Flow Solver ◽  
Water Reactor ◽  
Highly Sensitive ◽  
Transition Criteria

For the purpose of nuclear safety analysis, a reactive flow solver has been developed to determine the hazard potential of large-scale hydrogen explosions. Without using empirical transition criteria, the whole combustion process (including DDT) is computed within a single solver framework. In this paper, we present massively parallelized three-dimensional explosion simulations in a full-scale pressurized water reactor of the Konvoi type. Several generic DDT scenarios in globally lean hydrogen-air mixtures are examined to assess the importance of different input parameters. It is demonstrated that the explosion process is highly sensitive to mixture composition, ignition location and thermodynamic initial conditions. Pressure loads on the confining structure show a profoundly dynamic behavior depending on the position in the containment.

Computational Fluid Dynamics Simulation of Deflagration-to-Detonation Transition in a Full-Scale Konvoi-Type Pressurized Water Reactor

2017 ◽  
Vol 3 (4) ◽  
Author(s):  
Josef Hasslberger ◽  
Peter Katzy ◽  
Lorenz R. Boeck ◽  
Thomas Sattelmayer
Keyword(s):  
Initial Conditions ◽  
Combustion Process ◽  
Computational Cost ◽  
Full Scale ◽  
Dynamics Simulation ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Deflagration To Detonation Transition ◽  
Detonation Transition

For the purpose of nuclear safety analysis, a reactive flow solver has been developed to determine the hazardous potential of large-scale hydrogen explosions. Without using empirical transition criteria, the whole combustion process including deflagration-to-detonation transition (DDT) is computed within a single solver framework. In this paper, we present massively parallelized three-dimensional explosion simulations in a full-scale pressurized water reactor (PWR) of the Konvoi type. Several generic DDT scenarios in globally lean hydrogen–air mixtures are examined to assess the importance of different input parameters. It is demonstrated that the explosion process is highly sensitive to mixture composition, ignition location, and thermodynamic initial conditions. Pressure loads on the confining structure show a profoundly dynamic behavior depending on the position in the containment. Computational cost can effectively be reduced through adaptive mesh refinement (AMR).

Simulation of JAERI Downcomer Effective Water Head Experiments With WCOBRA/TRAC-TF2

2018 ◽  
Author(s):  
Jeffrey R. Kobelak ◽  
Jun Liao ◽  
Katsuhiro Ohkawa
Keyword(s):  
Hydraulic System ◽  
Large Scale ◽  
Reactor Vessel ◽  
Test Facility ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
System Pressure ◽  
Water Head ◽  
Effective Water

During the reflood phase of a postulated large break loss-of-coolant accident (LBLOCA), the liquid head in the reactor vessel downcomer provides the driving force to reflood the core. Since the reflood rate is a function of the downcomer inventory, the calculation of the downcomer liquid inventory is critical in simulating the reflood phase of a postulated LBLOCA accident in a pressurized water reactor. Since the reactor coolant system pressure decreases rapidly after the onset of a LBLOCA transient, the walls surrounding the downcomer become superheated for the duration of the transient. The Japan Atomic Energy Research Institute (JAERI) downcomer effective water head test facility was designed to study boiling and steam-water interaction in the reactor vessel downcomer under prototypical reflood conditions. A number of tests were conducted at this facility with varying degrees of wall superheating (among other things) that cover the expected degree of superheating in a pressurized water reactor. The wall superheating achieved at the JAERI facility is greater than that of other large-scale facilities that are typically simulated to validate thermal-hydraulic system codes. WCOBRA/TRAC-TF2 is the thermal-hydraulic system code utilized in the FULL SPECTRUM™ LOCA (FSLOCA™) evaluation model (EM). The ability of the WCOBRA/TRAC-TF2 code to predict phenomena occurring in the reactor vessel downcomer during the reflood phase of a postulated LBLOCA has been previously validated. However, only limited wall superheating was present in the existing validation basis. As such, two experiments conducted at the JAERI downcomer effective water head test facility are simulated to provide additional information on the capability of WCOBRA/TRAC-TF2 to predict the liquid inventory in the reactor vessel downcomer during the reflood phase of a postulated LBLOCA. The code captured all the trends observed in the experimental data for both Run 115 and Run 121. The various collapsed liquid levels tended to be well-predicted or under-predicted by the code after the initial simulated accumulator injection period.

Large Scale Pressurized Water Reactor Passive Containment Cooling System Wind Tunnel Test

2019 ◽  
Vol 5 (3) ◽  
Author(s):  
Huang Jingyu ◽  
Pan Xinxin ◽  
Song Chunjing
Keyword(s):  
Wind Tunnel ◽  
Large Scale ◽  
Cooling System ◽  
Air Flow ◽  
Wind Tunnel Test ◽  
Pressurized Water Reactor ◽  
Scaled Model ◽  
Pressurized Water ◽  
Water Reactor ◽  
Wind Speeds

The objective of the current work is to shed light on studying the air flow features of the air path which is part of the passive containment cooling system (PCS) in a pressurized water reactor design. A wind tunnel test using a 1:100 scaled model is established to study the characteristic called “wind-neutrality” of the air flow in the air path, which indicates that the environmental wind should not be beneficial or detrimental to the air flow for containment cooling. Test results show that the pressure distribution in the air path is uniform, and wind speeds, wind angles, and surroundings have little effect on air flow uniformity. These investigations show that it is possible to understand air flows in the air path of PCS with a scale wind tunnel test.

scholarly journals Thermodynamic consequences of hydrogen combustion within a containment of pressurized water reactor

2011 ◽  
Vol 32 (4) ◽  
pp. 67-79
Author(s):  
Tomasz Bury
Keyword(s):  
Nuclear Power ◽  
Large Scale ◽  
Nuclear Reactor ◽  
Computer Code ◽  
Hydrogen Combustion ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Lumped Parameter ◽  
Loss Of Coolant

Thermodynamic consequences of hydrogen combustion within a containment of pressurized water reactor Gaseous hydrogen may be generated in a nuclear reactor system as an effect of the core overheating. This creates a risk of its uncontrolled combustion which may have a destructive consequences, as it could be observed during the Fukushima nuclear power plant accident. Favorable conditions for hydrogen production occur during heavy loss-of-coolant accidents. The author used an own computer code, called HEPCAL, of the lumped parameter type to realize a set of simulations of a large scale loss-of-coolant accidents scenarios within containment of second generation pressurized water reactor. Some simulations resulted in high pressure peaks, seemed to be irrational. A more detailed analysis and comparison with Three Mile Island and Fukushima accidents consequences allowed for withdrawing interesting conclusions.

Comparison of Pressure-Temperature Limits for a Pressurized Water Reactor Pressure Vessel Considering Beltline and Extended Beltline Regions

2018 ◽  
Author(s):  
Hsoung-Wei Chou ◽  
Yu-Yu Shen ◽  
Chin-Cheng Huang
Keyword(s):  
Pressure Vessel ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Pressure Vessels ◽  
Reference Temperature ◽  
Regulatory Body ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor ◽  
Reactor Pressure

To ensure the structural integrity of the embrittled reactor pressure vessels (RPVs) during startup or shutdown operation, the pressure-temperature (P-T) limits are mainly determined by the fracture toughness of beltline region material with the highest level of neutron embrittlement. However, other vessel parts such as nozzles with structural discontinuities may affect the limits due to the higher stress concentration, even though the neutron embrittlement is insignificant. Therefore, not only beltline material with the highest reference temperature, but also other components with structural discontinuities have to be considered for the development of P-T limits of RPV. In the paper, the pressure-temperature operational limits of a Taiwan domestic pressurized water reactor (PWR) pressure vessel considering beltline and extended beltline regions are established per the procedure of ASME Code Section XI-Appendix G. The three-dimensional finite element models of PWR inlet and outlet nozzles above the beltline region are also built to analyze the pressure and thermal stress distributions for P-T limits calculation. The analysis results indicate that the cool-down P-T limit of the domestic PWR vessel is still dominated by the beltline region, but the heat-up limit is partially controlled by the extended beltline region. On the other hand, the relations of reference temperature between nozzles and beltline region on the P-T limits are also discussed. Present work could be a reference for the regulatory body and is also helpful for safe operation of PWRs in Taiwan.

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