PARIS project: Radiolytic oxidation of molecular iodine in containment during a nuclear reactor severe accident

2008 ◽  
Vol 238 (12) ◽  
pp. 3542-3550 ◽  
Author(s):  
L. Bosland ◽  
F. Funke ◽  
N. Girault ◽  
G. Langrock
Keyword(s):  
Nuclear Reactor ◽  
Molecular Iodine ◽  
Severe Accident ◽  
Radiolytic Oxidation

Experimental Investigation on Dependence of Decontamination Factor on Aerosol Number Concentration in Pool Scrubbing Under Normal Temperature and Pressure

2018 ◽  
Author(s):  
HaoMin Sun ◽  
Shinichi Machida ◽  
Yasuteru Sibamoto ◽  
Yuria Okagaki ◽  
Taisuke Yonomoto
Keyword(s):  
High Performance ◽  
Nuclear Reactor ◽  
Experimental System ◽  
Decontamination Factor ◽  
Number Concentration ◽  
Severe Accident ◽  
Measurement Instruments ◽  
Aerosol Number Concentration ◽  
Real Phenomenon ◽  
Validation Tests

During a severe accident of a nuclear reactor, radioactive aerosols may be released from degraded nuclear fuels. Pool scrubbing is one of the efficient filters with a high aerosol removal efficiency, in other words a high decontamination factor (DF). Because of its high performance, many pool scrubbing experiments have been performed and several pool scrubbing models have been proposed. In the existing pool scrubbing experiments, an experimental condition of aerosol number concentration was seldom taken into account. It is probably because DF is assumed to be independent of aerosol number concentration, at least, in the concentration where aerosol coagulation is limited. The existing pool scrubbing models also follow this assumption. In order to verify this assumption, we performed a pool scrubbing experiment with different aerosol number concentrations under the same boundary conditions. The test section is a transparent polycarbonate pipe with an inner diameter of 0.2 m. 0.5 μm SiO2 particles were used as aerosols. As a result, DF was increasing as decreasing the aerosol number concentration. In order to ensure a reliability of this result, three validation tests were performed with meticulous care. According to the results of these validation tests, it was indicated that DF dependence on the aerosol concentration was not because of our experimental system error including measurement instruments but a real phenomenon of the pool scrubbing.

scholarly journals Perspectives on a Severe Accident Consequences—10 Years after the Fukushima Accident

2021 ◽  
Vol 2 (4) ◽  
pp. 398-411
Author(s):  
Jinho Song
Keyword(s):  
Nuclear Reactor ◽  
Severe Accident ◽  
Accident Analysis ◽  
Fukushima Accident ◽  
The Public ◽  
Analysis Methodology ◽  
International Attention ◽  
Nuclear Reactor Safety ◽  
Term Monitoring

Scientific issues that draw international attention from the public and experts during the last 10 years after the Fukushima accident are discussed. An assessment of current severe accident analysis methodology, impact on the views of nuclear reactor safety, dispute on the safety of fishery products, discharge of radioactive water to the ocean, status of decommissioning, and needs for long-term monitoring of the environment are discussed.

The reduction of I2 by H2O2 in aqueous solution

2001 ◽  
Vol 79 (3) ◽  
pp. 304-311 ◽  
Author(s):  
J M Ball ◽  
J B Hnatiw
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Nuclear Reactor ◽  
Ph Dependence ◽  
Radiolysis Product ◽  
Molecular Iodine ◽  
Water Radiolysis ◽  
Reactor Accident ◽  
Rate Law ◽  
Accident Conditions

The reduction of I2 by hydrogen peroxide, a primary water radiolysis product, has been identified as a key reaction that would influence iodine volatility in nuclear reactor accident conditions (1–3). Although there have been a number of studies of the reduction of I2, there exists a great degree of controversy regarding the intermediates involved, the effect of buffers, and the general rate law (1–9). Because the rates and the mechanism of this reaction are important in predicting the pH dependence of iodine behaviour in reactor containment building after a postulated reactor accident, we have undertaken a kinetic study of I2 reduction by H2O2 in aqueous solution over a pH range of 6–9. The experiments were performed using stopped-flow instrumentation and monitoring the decay of I–3 spectrophotometrically. The effects of buffer catalysis have been examined by comparison of kinetic data obtained in sodium barbital (5,5-diethylbarbituric acid), disodium citrate, and disodium hydrogen phosphate buffers. The effect of buffers, combined with the complex acid dependence of the rate law, explains many of the discrepancies reported in earlier literature.Key words: hydrogen peroxide, molecular iodine, kinetics, iodine volatility.

Analysis Contour Plots in RELAP/SCDAPSIM/MOD 3.4 and MOD 4.1

2018 ◽  
Author(s):  
Heriberto Sánchez-Mora ◽  
Carlos Chávez-Mercado ◽  
Chris Allison ◽  
Judith Hohorst
Keyword(s):  
Nuclear Energy ◽  
Nuclear Reactor ◽  
Severe Accident ◽  
Energy Industry ◽  
Contour Plot ◽  
Input File ◽  
Systems Software ◽  
Contour Plots ◽  
Core Components ◽  
Control Rods

RELAP/SCDAPSIM is a nuclear reactor simulator and accident analysis code that has been used in the nuclear energy industry for many years. Currently, Innovative Systems Software is developing a new tool that will show the behavior of the core components during a simulation of an accident. The addition of contour plots for the SCDAP components showing different properties: temperature, hydrogen production, etc. will allow a better understanding of core behavior during a severe accident in a nuclear reactor. The SCDAP components are fuel rods, electrically heated simulator rods, such as those used in the CORA experiments, control rods, a shroud and a BWR blade/box. This paper describes the progress in the development of the contour plot tool based on the OpenGL and FORTRAN90 libraries. The purpose of this tool is help to the user analyze the simulation of an accident and to debug an input file.

Numerical Study of Fuel Melting and Molten Migration Based on the MPS Method

2020 ◽  
Author(s):  
Zhong Lei ◽  
Jian Deng ◽  
Wei Li ◽  
Xiaoli Wu ◽  
Chunrui Deng
Keyword(s):  
Nuclear Reactor ◽  
Initial Temperature ◽  
Numerical Study ◽  
Eutectic Reaction ◽  
Melting Process ◽  
Severe Accident ◽  
Migration Behavior ◽  
Mps Method ◽  
Water Reactors ◽  
Moving Particle

Abstract Core melting and molten migration behavior are hot and difficult issues in the field of nuclear reactor severe accident research. The Moving Particle Semi-implicit (MPS) meshless method has potential to simulate free-surface and multiphase flows. In this study, the MPS method was utilized to simulate the melting process of UO2-Zr rod-type fuel elements. The models of heat conduction with phase change, simplified UO2-Zr eutectic reaction, viscous flow and surface tension were implemented with the framework of standard MPS method. Then, the improved MPS code was used to simulate and analyze the process of high-temperature melting and characteristics of molten migration and solidification in the coolant channel, aiming at revealing the severe accidents for light water reactors (LWR), particularly the early core damage. The results showed that compared with the case of higher initial temperature, when the initial temperature of molten UO2 is lower, more molten UO2 will solidify on the surface of rod cluster, and the blockage of upper flow channel caused by molten UO2 is more serious. In addition, this study also demonstrated the potential of the MPS method for the study of complicated severe accident phenomena in not only traditional LWR but also advanced nuclear reactors in the future.

Enhancing Probabilistic Risk Assessment Methodology for Solving Reactor Safety Issues

2003 ◽  
Author(s):  
F. L. Cho
Keyword(s):  
Nuclear Reactor ◽  
Severe Accident ◽  
Assessment Methodology ◽  
Reactor Safety ◽  
Reactor Accident ◽  
Safety Issues ◽  
Damage States ◽  
Baseline Information ◽  
Risk Assessment Methodology ◽  
Accident Sequences

This paper reveals a paradigm of analyzing the consequential effects of severe nuclear reactor accident, radionuclides fraction and source terms release, that will influence the MACCS2 codification [1], by coupling with the results of SAPHIA-PSA Levels l & 2 quantification process [2], MELCORE [3], STCP [4], PST [5], and XSOR [6]. Those codes are mutually exclusive and useful. However, it lacks of the closed interface and linkage for addressing Plant Damage States (PDS), Severe Accident Sequences, and Risk Consequence. Thus, it is imperative to formulate the consistent baseline information for MACCS2, PSA Levels 1, 2 and 3, and then linking to a new algorithm of NCM.

CORBA AND MPI-BASED “BACKBONE” FOR COUPLING ADVANCED SIMULATION TOOLS

2014 ◽  
Vol 3 (2) ◽  
pp. 83-90 ◽  
Author(s):  
M. Seydaliev ◽  
D. Caswell
Keyword(s):  
Fission Product ◽  
Computer Simulations ◽  
Message Passing ◽  
Message Passing Interface ◽  
Nuclear Reactor ◽  
Atmospheric Dispersion ◽  
Safety Analysis ◽  
Severe Accident ◽  
Nuclear Reactor Safety ◽  
Exchange Data

There is a growing international interest in using coupled, multidisciplinary computer simulations for a variety of purposes, including nuclear reactor safety analysis. Reactor behaviour can be modeled using a suite of computer programs simulating phenomena or predicting parameters that can be categorized into disciplines such as Thermalhydraulics, Neutronics, Fuel, Fuel Channels, Fission Product Release and Transport, Containment and Atmospheric Dispersion, and Severe Accident Analysis. Traditionally, simulations used for safety analysis individually addressed only the behaviour within a single discipline, based upon static input data from other simulation programs. The limitation of using a suite of stand-alone simulations is that phenomenological interdependencies or temporal feedback between the parameters calculated within individual simulations cannot be adequately captured. To remove this shortcoming, multiple computer simulations for different disciplines must exchange data during runtime to address these interdependencies. This article describes the concept of a new framework, which we refer to as the “Backbone,” to provide the necessary runtime exchange of data. The Backbone, currently under development at AECL for a preliminary feasibility study, is a hybrid design using features taken from the Common Object Request Broker Architecture (CORBA), a standard defined by the Object Management Group, and the Message Passing Interface (MPI), a standard developed by a group of researchers from academia and industry. Both have well-tested and efficient implementations, including some that are freely available under the GNU public licenses. The CORBA component enables individual programs written in different languages and running on different platforms within a network to exchange data with each other, thus behaving like a single application. MPI provides the process-to-process intercommunication between these programs. This paper outlines the different CORBA and MPI configurations examined to date, as well as the preliminary configuration selected for coupling 2 existing safety analysis programs used for modeling thermal–mechanical fuel behavior and fission product behavior respectively. In addition, preliminary work in hosting both the Backbone and the associated safety analysis programs in a cluster environment are discussed.

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