Effect of Spray System on in Containment Fission Product Washout During In-Vessel Release Phase

2017 ◽  
Author(s):  
Khurram Mehboob ◽  
Mohammad. S. Aljohani
Keyword(s):  
Sensitivity Analysis ◽  
Droplet Size ◽  
Removal Rate ◽  
Absorption Efficiency ◽  
Radioactive Isotopes ◽  
Activation Time ◽  
Spray System ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Mean Size

The response of containment sprinkles during the in-vessel release phase of low-pressure loss of coolant accident (LOCA) has for two-loop PWR been simulated. Cleaning and wash out of radioactive isotopes is essential to limit the risk of radioactive exposure. An uncontrolled LOCA has been selected for this study. In this work, numerical simulation of spray system with its parameter has been carried out to study the sensitivity analysis of airborne radioactive isotopes on spray system parameters. Therefore, we have developed a kinetic model and implemented in MATLAB which used the ORIGEN 2.2 as a subroutine code. The sensitivity analysis and airborne isotopes and removal rate has been carried out for spray activation time, droplet size. It has been seen that the droplets mean size plays an important role in containment washout. The droplet absorption ratio indicates that the smaller droplet size has higher absorption efficiency.

scholarly journals Numerical Simulation of Decontamination of Airborne Fission Products during In-Vessel Release Phase by Containment Spray

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Khurram Mehboob
Keyword(s):  
Droplet Size ◽  
Failure Time ◽  
Ph Value ◽  
Removal Rate ◽  
Droplet Diameter ◽  
Fission Products ◽  
Product Release ◽  
Spray System ◽  
Spray Solution ◽  
Proposed Model

The containment spray system (CSS) has a significant role in limiting the risk of radioactive exposure to the environment. In this work, the optimal droplet size and pH value of spray water to prevent the fission product release have been evaluated to improve the performance of the spray system during in-vessel release phase. A semikinetic model has been developed and implemented in MATLAB. The sensitivity and removal rate of airborne isotopes with the spray system have been simulated versus the spray activation and failure time, droplet size, and pH value. The alkaline (Na2S2O3) spray solution and spray water with pH 9.5 have similar scrubbing properties for iodine. However, the removal rate from the CSS has been found to be an approximately inverse square of droplet diameter (1/d2) for Na2S2O3 and higher pH of spray water. The numerical results showed that 450 μm–850 μm droplet with 9.5 pH and higher or the alkaline (Na2S2O3) solution with 0.2 m3/s–0.35 m3/s flow rate is optimal for effective scrubbing of in-containment fission products. The proposed model has been validated with TOSQAN experimental data.

Sensitivity Analysis of the Response of PWR Containment During a Loss of Coolant Accident Using RELAP5-3D and MELCOR

2014 ◽  
Author(s):  
Rodolfo Vaghetto ◽  
Andrew Franklin ◽  
Alessandro Vanni ◽  
Yassin A. Hassan
Keyword(s):  
Sensitivity Analysis ◽  
Discharge Coefficient ◽  
Physical Models ◽  
Geometrical Parameters ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Flow Models ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Selection Of

The prediction of specific parameters for the reactor containment, such as pressure and sump pool temperature, is of paramount importance when studying the thermal-hydraulic phenomena involved in the debris generation, transport, and accumulation during Loss of Coolant Accidents (LOCA). The response of the reactor containment during these events may significantly vary depending of several factors such as break size and location, and other plant-specific features. When modeling the reactor and containment response using systems codes, the predictions may also depend on the selection of physical models, correlations and their coefficients. A sensitivity analysis of the response of a typical Pressurized Water Reactor (PWR) 4-loop reactor system and associated containment during a large break LOCA was conducted using RELAP5-3D and MELCOR to investigate the influence of geometrical parameters (break location), physical models (chiked flow models), and related coefficients (discharge coefficient at the break), on the containment response. The simulation results showed how the containment response changed by varying the selected parameters and confirmed the importance of identifying and studying the factors triggering the containment engineered features (containment sprays) when simulation the containment response.

Prediction of Pressure Propagation in Piping Systems After ISLOCA

2014 ◽  
Author(s):  
Takeshi Yamada ◽  
Kohei Hisamochi ◽  
Taichi Takii ◽  
Kenichi Yasuda
Keyword(s):  
Sensitivity Analysis ◽  
Transient Behavior ◽  
Maximum Pressure ◽  
Loss Of Coolant Accident ◽  
Loss Of Coolant ◽  
Interface System ◽  
Piping Systems ◽  
Pipe Line ◽  
Valve Opening ◽  
Pressure Propagation

Interface-System Loss-of-Coolant Accident (ISLOCA) occurs by failure of isolation valves in piping systems. In this study, transient behavior of pressure propagation in piping systems after ISLOCA has been estimated. At first, capability of TRACG code to predict pressure propagation in a simple pipe line, which has expansion, contraction and bifurcation, has been investigated. Then, sensitivity analysis of valve opening period has been performed to investigate the behavior of pressure propagation in a simple pipe line. Finally, pressure propagation inside piping systems after ISLOCA has been simulated for Hitachi-GE standard Advanced boiling water reactor (ABWR) plant. Maximum pressure inside High Pressure Core Flooder (HPCF) systems has been less than 7.8MPa. TRACG code has been shown to be useful to predict transient behavior of pressure propagation in complicated network of piping systems after ISLOCA.

scholarly journals A Study of Prediction Model Improvement for Air-Oxidation Breakaway in a Postulated Spent Nuclear Fuel Pool Complete Loss of Coolant Accident

2021 ◽  
Vol 13 (3) ◽  
pp. 1442
Author(s):  
Sanggil Park ◽  
Jaeyoung Lee ◽  
Min Bum Park
Keyword(s):  
Kinetic Model ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Complete Loss ◽  
Air Oxidation ◽  
Loss Of Coolant Accident ◽  
Spent Nuclear Fuel Pool ◽  
Loss Of Coolant ◽  
Model Derivation ◽  
Model Improvement

The temperature of zirconium alloy cladding on the postulated spent nuclear fuel pool complete loss of coolant accident is abruptly increased at a certain time and the cladding is almost fully oxidized to weak ZrO2 in the air. This abrupt temperature escalation phenomenon induced by the air-oxidation breakaway is called a zirconium fire. Although an air-oxidation breakaway kinetic model correlated between time and temperature has been implemented in the MELCOR code, it is likely to bring about unexpected large errors because of many limitations of model derivation. This study suggests an improved time–temperature correlated kinetic model using the Johnson–Mehl equation. It is based on that the air-oxidation breakaway is initiated by the phase transformation from the tetragonal to monoclinic ZrO2 at the oxide–metal interface in the cladding. This new model equation is also evaluated with the Zry-4 air-oxidation literature data. This equation resulted in the almost similar air-oxidation breakaway timing to the actual experimental data at 800 °C. However, at 1000 °C, it showed an error of about 8 min. This could be inferred from the influence of the ZrN phase change due to the nitrogen existing in air.

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