Simulation of Aerosol Behavior in a Saturated Atmosphere With the CONTAIN Code

2002 ◽  
Author(s):  
Ivo Kljenak ◽  
Borut Mavko
Keyword(s):  
Nuclear Power ◽  
Saturated Vapor ◽  
Computer Code ◽  
Light Water Reactor ◽  
Severe Accident ◽  
Experimental Facility ◽  
Standard Problem ◽  
Model Aerosol ◽  
Saturated Atmosphere ◽  
Accident Conditions

Experiments on aerosol behavior in an atmosphere containing saturated vapor, which were performed in the KAEVER experimental facility and proposed for the OECD International Standard Problem No. 44, were simulated with the CONTAIN thermal-hydraulic computer code. The purpose of the work was to assess the capability of the CONTAIN code to model aerosol condensation and deposition in a containment of a light-water-reactor nuclear power plant at severe accident conditions. Results of dry and wet aerosol concentrations in the test vessel atmosphere are presented and analyzed.

Simulation of the HDR E11.2 Hydrogen Mixing Experiment With the CONTAIN Code

2002 ◽  
Author(s):  
Aljaz Skerlavaj ◽  
Ivo Kljenak
Keyword(s):  
Thermal Stratification ◽  
Nuclear Power ◽  
Computer Code ◽  
Severe Accident ◽  
Test Facility ◽  
Hydrogen Distribution ◽  
Flow Geometry ◽  
Input Model ◽  
Containment Test ◽  
Accident Conditions

One of the most well-known experiments on atmosphere stratification in a nuclear power plant containment at severe accident conditions is the test E11.2 “Hydrogen distribution in loop flow geometry”, which was performed in the Heissdampf Reaktor containment test facility in Germany. In the present work, the simulation of the test E11.2 with the CONTAIN computer code is presented. An input model consisting of 72 cells and 263 flowpaths was developed. The predicted pressure history and thermal stratification agree relatively well with the measurements. The compositional stratification within the containment was qualitatively well predicted, although the degree of the stratification in the dome area was somewhat underestimated.

scholarly journals Radiation-Tolerance Assessment of a Redundant Wireless Device

2018 ◽  
Vol 170 ◽  
pp. 03004
Author(s):  
Q. Huang ◽  
J. Jiang
Keyword(s):  
Nuclear Power ◽  
Evaluation Method ◽  
Radiation Condition ◽  
Severe Accident ◽  
Radiation Environment ◽  
Radiation Tolerance ◽  
Monitoring Device ◽  
Wireless Monitoring ◽  
Study Results ◽  
Accident Conditions

This paper presents a method to evaluate radiation-tolerance without physical tests for a commercial off-the-shelf (COTS)-based monitoring device for high level radiation fields, such as those found in post-accident conditions in a nuclear power plant (NPP). This paper specifically describes the analysis of radiation environment in a severe accident, radiation damages in electronics, and the redundant solution used to prolong the life of the system, as well as the evaluation method for radiation protection and the analysis method of system reliability. As a case study, a wireless monitoring device with redundant and diversified channels is evaluated by using the developed method. The study results and system assessment data show that, under the given radiation condition, performance of the redundant device is more reliable and more robust than those non-redundant devices. The developed redundant wireless monitoring device is therefore able to apply in those conditions (up to 10 M Rad (Si)) during a severe accident in a NPP.

Study of the Ageing Effects on the Lower Head Failure in a PWR Reactor

2020 ◽  
Author(s):  
R. Lo Frano ◽  
S. Paci ◽  
P. Darnowski ◽  
P. Mazgaj
Keyword(s):  
Nuclear Power ◽  
Quantitative Estimation ◽  
Computer Code ◽  
Severe Accident ◽  
Symmetric Model ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Term Operation ◽  
Ageing Effects ◽  
Lower Head

Abstract The paper studies influence the ageing effects on the failure of a Reactor Pressure Vessel (RPV) during a severe accident with a core meltdown in a Nuclear Power Plant (NPP). The studied plant is a generic high-power Generation III Pressurized Water Reactor (PWR) developed in the frame of the EU NARSIS project. A Total Station Blackout (SBO) accident was simulated with MELCOR 2.2 severe accident integral computer code. Results of the analysis, temperatures in the lower head and pressures in the lower plenum were used as initial and boundary conditions for the Finite Element Method (FEM) simulations. Two FEM models were developed, a simple two-dimensional axis-symmetric model of the lower head to study fundamental phenomena and complex 3D model to include interactions with the RPV and reactor internals. Ageing effects of a lower head were incorporated into the FEM models to investigate its influence onto lower head response. The ageing phenomena are modelled in terms of degraded mechanical material properties as σ(T), E(T). The primary outcome of the study is the quantitative estimation of the influence of ageing process onto the timing of reactor vessel failure. Presented novel methodology and results can have an impact on future consideration about Long-Term Operation (LTO) of NPPs.

Simulation of Gas Stratification Build-Up in the Containment Under Severe Accident Conditions

2014 ◽  
Author(s):  
Michele Andreani
Keyword(s):  
Structural Integrity ◽  
Computer Code ◽  
Severe Accident ◽  
Test Sequence ◽  
Small Scale ◽  
High Concentration ◽  
Initial Transient ◽  
Loss Of Coolant Accident ◽  
Computer Codes ◽  
Accident Conditions

The presence of hydrogen stratification in a NPP containment in the case of a severe accident is a source of concern, as pockets of the gas in high concentration could lead to a deflagration or detonation risk, which might challenge the containment structural integrity. These issues, as well as the capability of various computer codes to predict the evolution of a representative accident, are addressed in the coordinated projects ERCOSAM of the 7th EURATOM FWP and the project SAMARA sponsored by ROSATOM. The projects aim to establish whether in a test sequence representative of a severe accident in a LWR hydrogen stratification can be established during the initial transient following a loss of coolant accident (LOCA) and whether and how this stratification can be broken down by the operation of Severe Accident Management systems (SAMs): sprays, coolers and Passive Auto-catalytic Recombiners (PARs). Experiments with helium (as simulant of hydrogen) have been performed at “small scale” in TOSQAN (IRSN, Saclay), and “medium scale” in the MISTRA (CEA, Saclay), PANDA (PSI, Villigen) and SPOT ((JSC “Afrikantov OKBM”, Nizhny Novgorod) facilities. The present paper presents the analysis of the initial transient of some tests in the PANDA, TOSQAN and SPOT facilities using the GOTHIC computer code. The work therefore addresses the capability of the code and a relatively coarse mesh to simulate the pressurisation and build-up of steam and helium stratification for conditions representative of a postulated severe accident scenario, properly scaled to the various facilities. The prediction of the pressurisation is excellent, and the position of the gas concentration stratification front at the end of the steam and helium releases is generally well captured.

scholarly journals Steam Oxidation of Silicon Carbide at High Temperatures for the Application as Accident Tolerant Fuel Cladding, an Overview

Thermo ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 151-167
Author(s):  
Hai V. Pham ◽  
Masaki Kurata ◽  
Martin Steinbrueck
Keyword(s):  
Silicon Carbide ◽  
High Temperatures ◽  
Nuclear Power ◽  
Steam Oxidation ◽  
Severe Accident ◽  
Light Water Reactors ◽  
Severe Accidents ◽  
Potential Benefits ◽  
Water Reactors ◽  
Accident Conditions

Since the nuclear accident at Fukushima Daiichi Nuclear Power Station in 2011, a considerable number of studies have been conducted to develop accident tolerant fuel (ATF) claddings for safety enhancement of light water reactors. Among many potential ATF claddings, silicon carbide is one of the most promising candidates with many superior features suitable for nuclear applications. In spite of many potential benefits of SiC cladding, there are some concerns over the oxidation/corrosion resistance of the cladding, especially at extreme temperatures (up to 2000 °C) in severe accidents. However, the study of SiC steam oxidation in conventional test facilities in water vapor atmospheres at temperatures above 1600 °C is very challenging. In recent years, several efforts have been made to modify existing or to develop new advanced test facilities to perform material oxidation tests in steam environments typical of severe accident conditions. In this article, the authors outline the features of SiC oxidation/corrosion at high temperatures, as well as the developments of advanced test facilities in their laboratories, and, finally, give some of the current advances in understanding based on recent data obtained from those advanced test facilities.

scholarly journals Investigation on Aerosol Pool Scrubbing Model During Severe Accidents

2021 ◽  
Vol 9 ◽  
Author(s):  
L. W. He ◽  
Y. X. Li ◽  
Y. Zhou ◽  
S. Chen ◽  
L. L. Tong ◽  
...  
Keyword(s):  
Bubble Size ◽  
Nuclear Power ◽  
Predictive Ability ◽  
Decontamination Factor ◽  
Light Water Reactor ◽  
Severe Accident ◽  
Spent Fuel ◽  
Analysis Model ◽  
Light Water ◽  
Water Reactor

During a nuclear power plant severe accident, discharging gas mixture into the spent-fuel pool is an alternative containment depressurization measurement through which radioactive aerosols can be scrubbed. However, it is necessary to develop a code for analyzing the decontamination factor of aerosol pool scrubbing. This article has established the analysis model considering key aerosol pool scrubbing mechanisms and introduced the Akita bubble size relationship. In addition, a code for evaluating the decontamination factor of aerosol pool scrubbing was established. The Advanced Containment Experiment and Light Water Reactor Advanced Containment Experiment were simulated with the code considering different bubble sizes of the Akita model and MELCOR default value to verify the suitability of the Akita bubble size model for simulating aerosol pool scrubbing. Furthermore, the simulation results were compared with the results analyzed by MELCOR code and COCOSYS code from literature, and equivalent predictive ability was observed. In addition, a sensitivity analysis on bubble size was conducted, and the contribution of different behaviors and mechanisms has been discussed. Finally, the bubble breakup equation was revised and verified with the conditions of the multi-hole bubbler in the Advanced Containment Experiment and Light Water Reactor Advanced Containment Experiment.

Development and Verification of Severe Accident Simulation Capability for a NPP Simulator

2013 ◽  
Author(s):  
Zhifei Yang ◽  
Xiaofei Xie ◽  
Xing Chen ◽  
Shishun Zhang ◽  
Yehong Liao ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Simulation System ◽  
Severe Accident ◽  
Normal Operation ◽  
Feed Water ◽  
Accident Simulation ◽  
Accident Conditions ◽  
Relap5 Code

It is reflected in the severe accident in Fukushima Daiichi that the emergency capacity of nuclear power plant needs to be enhanced. A nuclear plant simulator that can model the severe accident is the most effective means to promote this capacity. Until now, there is not a simulator which can model the severe accident in China. In order to enhance the emergency capacity in China, we focus on developing a full scope simulator that can model the severe accident and verify it in this study. The development of severe accident simulation system mainly includes three steps. Firstly, the integral severe accident code MELCOR is transplanted to the simulation platform. Secondly, the interface program must be developed to switch calculating code from RELAP5 code to MELCOR code automatically when meeting the severe accident conditions because the RELAP5 code can only simulate the nuclear power plant normal operation state and design basis accident but the severe accident. So RELAP5 code will be stopped when severe accident conditions happen and the current nuclear power plant state parameters of it should be transported to MELCOR code, and MELCOR code will run. Finally, the CPR1000 nuclear power plant MELCOR model is developed to analyze the nuclear power plant behavior in severe accident. After the three steps, the severe accident simulation system is tested by a scenario that is initiated by the station black out with reactor cooling pump seal leakage, HHSI, LHSI and auxiliary feed water system do not work. The simulation result is verified by qualitative analysis and comparison with the results in severe accident analysis report of the same NPP. More severe accident scenarios initiated by LBLOCA, MBLOCA, SBLOCA, SBO, ATWS, SGTR, MSLB will be tested in the future. The results show that the severe accident simulation system can model the severe accident correctly; it meets the demand of emergency capacity promotion.

Modeling of QUENCH 10 Experiment on Air Ingress Using RELAP/SCDAPSIM Mod 3.5

2017 ◽  
Author(s):  
Tadas Kaliatka ◽  
Eugenijus Uspuras ◽  
Chris M. Allison
Keyword(s):  
Computer Code ◽  
Light Water Reactor ◽  
Severe Accident ◽  
Model Assessment ◽  
Significant Group ◽  
Accident Management ◽  
Management Measure ◽  
The Subject ◽  
Air Ingress ◽  
Code Version

The most important accident management measure to terminate a severe accident transient in a light water reactor is the injection of water to cool the uncovered degraded core. Several experimental and analytical investigations have been made on the subject of zirconium oxidation in the steam and air environment during the last 15 years. The significant group of experiments are the experiments, performed in QUENCH facility. QUENCH-10 experiment was the first experiment from the all QUENCH experiment series with air ingress. In this article, the RELAP/SCDAPSIM mod 3.5 code version and implemented different oxidation correlations were used to analyze the air ingress experiment QUENCH-10 with the purpose to perform the code and model assessment. The results of analysis will be used in the future computer code improvement and to increase the competence of code users.

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