Iodine Benchmarks in the SARNET Network of Excellence

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Tim Haste ◽  
Mirco Di Giuli ◽  
Gunter Weber ◽  
Sebastian Weber
Keyword(s):  
Molecular Iodine ◽  
Major Influence ◽  
Thermal Hydraulics ◽  
Atmospheric Flows ◽  
Organic Iodine ◽  
Severe Accidents ◽  
Hydraulic Conditions ◽  
Iodine Transport ◽  
Modeling Code ◽  
Radioactive Release

Accurate calculation of iodine behavior in the containment is very important in determining the potential radioactive release to the environment in light water reactor severe accidents (SAs). Of particular significance is the behavior of gas phase iodine, particularly organic iodine, which is difficult to remove by filtration, e.g., in containment venting systems. Iodine behavior is closely linked with the containment thermal hydraulics, which have a major influence on the distribution of iodine throughout the containment atmosphere and sump. In the European 7th Framework SARNET project, European Commission (EC) cofunded from 2007 to 2013, SA modeling code capability was assessed through two integral benchmarks. In the first, the basis was the German THAI Iod-11/12 tests, where molecular iodine transport with atmospheric flows and iodine interactions with steel surfaces were emphasized. In the second, data from the international Phébus FPT3 test were used, where all aspects of SAs were studied from core degradation, fission product (FP) release, circuit transport/deposition, and containment behavior using realistic FP sources. Thermal hydraulics in the containment were simpler, being well-mixed, and radiolytic interactions of iodine, e.g., with painted surfaces, were studied. These interactions may be an important source of organic iodine in the containment atmosphere. The two benchmarks are thus complementary. In the FPT3 exercise, the calculations could predict the containment thermal hydraulic conditions fairly well. For the more detailed data from THAI, differences were noted for atmospheric flows and relative humidities, outside experimental uncertainties, affecting iodine behavior. The FPT3 iodine results themselves showed a spread in calculated results outside data uncertainties, indicating the need for model improvements in this area, e.g., for radiolytic interaction of iodine with paint. Experimental programs to generate the necessary data needed for code improvement have been recently completed, e.g., in the OECD/THAI, THAI2, BIP, and BIP2 projects, or are in progress, in OECD/STEM and EC/PASSAM. When model improvements have been made, repeat benchmarks are planned to check progress toward code convergence with experimental data, e.g., under the aegis of the new NUGENIA association of which SARNET now forms a part.

Iodine and Halocarbon Response of Laminaria digitata to Oxidative Stress and Links to Atmospheric New Particle Production

2005 ◽  
Vol 2 (4) ◽  
pp. 282 ◽  
Author(s):  
Carl J. Palmer ◽  
Thorsten L. Anders ◽  
Lucy J. Carpenter ◽  
Frithjof C. Küpper ◽  
Gordon B. McFiggans
Keyword(s):  
Oxidative Stress ◽  
Particle Production ◽  
Marine Boundary Layer ◽  
Oxidative Capacity ◽  
Molecular Iodine ◽  
Laminaria Digitata ◽  
Organic Iodine ◽  
Free Air ◽  
Iodine Compounds ◽  
Iodine Release

Environmental Context.Various organic iodine compounds (including CH3I, CH2ClI, CH2BrI, CH2I2) are present throughout the marine boundary layer as a result of their production from seaweeds, phytoplankton, and photolysis reactions occurring in seawater. In air, these compounds rapidly photolyse to give atomic I which subsequently reacts with ozone to form iodine oxide, potentially leading to perturbations of the tropospheric oxidative capacity and nucleation of atmospheric particles. Recent research has identified molecular iodine as an additional source of iodine atoms to coastal areas. Here we study the relative roles and controls of gaseous organic and molecular iodine release from the seaweed Laminaria digitata. Abstract.Changes in the halocarbon, I2 and particle production of the brown algal kelp Laminaria digitata as a response to different chemical stresses have been investigated. Oxidative stress (caused by either exogenous hydrogen peroxide, gaseous ozone or a solution of oligoguluronates, known elicitors of oxidative stress) caused increased halocarbon and I2 production by the seaweed. The maximum I2 release was observed under exposure to O3 (at several hundred parts per billion by volume (ppbv)), whereas oligoguluronates elicited the highest release of iodine-containing halocarbons including CH2I2. Significantly greater production of I2, compared to CH2I2, was observed at atmospheric levels of ozone. Particle production was observed only when the Laminaria samples were exposed to ozone (up to 16 000 cm−3 s−1 per gram fresh weight (FW) of seaweed with a ~2 min residence time and with a total I atom flux of 1.6 × 108 cm−3 s−1 g−1 FW from photolysis of I2); passing O3-free air over the unstressed seaweed followed by secondary mixing with ozone did not result in any measurable particle formation. Our limited data indicate that ozone elicits abiotic production of I2 from Laminaria and that there is a direct relationship between the amount of I2 released and the number of particles formed. The results support the recent hypothesis that molecular iodine rather than volatile organic iodine (e.g. CH2I2) release from exposed seaweeds is the major source of coastal new particle production.

Posttest Calculations of PARAMETER-SF4 Experiment With Air Ingress and Water Reflood Using SOCRAT/V3 Computer Modeling Code

2011 ◽  
Author(s):  
Alexander Vasiliev
Keyword(s):  
Experimental Data ◽  
Computer Modeling ◽  
Nuclear Power ◽  
Cooling System ◽  
Thermal Hydraulics ◽  
Pressurized Water ◽  
Vver Fuel ◽  
Design Basis ◽  
Air Ingress ◽  
Modeling Code

The PARAMETER-SF4 test conditions simulated a severe LOCA (Loss of Coolant Accident) NPP (nuclear power plant) sequence in which the overheated up to 1700–2300K core would be reflooded from the bottom in occasion of ECCS (Emergency Core Cooling System) recovery. The test was successfully conducted at the NPO “LUTCH”, Podolsk, Russia, in July 21, 2009, and was the fourth of four experiments of series PARAMETER-SF. PARAMETER facility of NPO “LUTCH” (scientific and industrial association LUTCH), Podolsk, is designed for studies of the VVER fuel assemblies behavior under conditions simulating design basis, beyond design basis and severe accidents. The test bundle was made up of 19 fuel rod simulators. Heating was carried out electrically using tantalum heating elements installed in the center of the rods and surrounded by annular UO2 pellets. The rod cladding was identical to that used in VVER (water-water energetic reactor, Russian type of pressurized water reactor). After the maximum cladding temperature of about 1900K was reached in the bundle during PARAMETER-SF4 test, the bottom flooding was initiated. The important feature of PARAMETER-SF4 test was the air ingress phase during which the air was supplied to the working section of experimental installation. It is known that zirconium oxidation in the air proceeds in a different way in comparison to oxidation in the steam. The thermal hydraulic and SFD (Severe Fuel Damage) best estimate computer modeling code SOCRAT/V3 was used for the calculation of PARAMETER-SF4 experiment. Thermal hydraulics in PARAMETER-SF4 experiment played very important role and its adequate modeling is important for the thermal analysis. The results obtained by the complex SOCRAT/V3 were compared with experimental data concerning different aspects of air ingress phase and thermal hydraulics behavior during the reflood. The temperature experimental data were found to be in a good agreement with calculated results. It is indicative of the adequacy of modeling the complicated thermo-hydraulic behavior in the PARAMETER-SF4 test.

scholarly journals Thermal Hydraulics Analysis of the Distribution Zone in Small Modular Dual Fluid Reactor

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1065
Author(s):  
Chunyu Liu ◽  
Xiaodong Li ◽  
Run Luo ◽  
Rafael Macian-Juan
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Heat Removal ◽  
Core Region ◽  
Major Influence ◽  
Liquid Lead ◽  
Thermal Hydraulics ◽  
The Core ◽  
Removal Capacity ◽  
Power Peak

The Small Modular Dual Fluid Reactor (SMDFR) is a novel molten salt reactor based on the dual fluid reactor concept, which employs molten salt as fuel and liquid lead/lead-bismuth eutectic (LBE) as coolant. A unique design of this reactor is the distribution zone, which locates under the core and joins the core region with the inlet pipes of molten salt and coolant. Since the distribution zone has a major influence on the heat removal capacity in the core region, the thermal hydraulics characteristics of the distribution zone have to be investigated. This paper focuses on the thermal hydraulics analysis of the distribution zone, which is conducted by the numerical simulation using COMSOL Multiphysics with the CFD (Computational Fluid Dynamics) module and the Heat Transfer module. The energy loss and heat exchange in the distribution zone are also quantitatively analyzed. The velocity and temperature distributions of both molten salt and coolant at the outlet of the distribution zone, as inlet of the core region, are produced. It can be observed that the outlet velocity profiles are proportional in magnitude to the inlet velocity ones with a similar shape. In addition, the results show that the heat transfer in the center region is enhanced due to the velocity distribution, which could compensate the power peak and flatten the temperature distribution for a higher power density.

ASTEC, COCOSYS, and LIRIC Interpretation of the Iodine Behavior in the Large-Scale THAI Test Iod-9

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
G. Weber ◽  
L. Bosland ◽  
F. Funke ◽  
G. Glowa ◽  
T. Kanzleiter
Keyword(s):  
Mass Transfer ◽  
Large Scale ◽  
Saint Paul ◽  
Molecular Iodine ◽  
Severe Accident ◽  
Research Network ◽  
Lumped Parameter ◽  
Post Test ◽  
Iodine Test ◽  
Iodine Transport

The large-scale iodine test Iod-9 of the German Thermal hydraulics, Hydrogen, Aerosols, Iodine (THAI) program was jointly interpreted by means of post-test analyses within the THAI Circle of the Severe Accident Research NETwork (SARNET)/Work Package 16. In this test, molecular iodine (I2) was injected into the vessel dome of the 60 m3 THAI vessel to observe the evolution of its distribution between water, gas, and surfaces. The main processes addressed in Iod-9 are (a) the mass transfer of I2 between the gas and the two sumps, (b) the iodine transport in the main sump when it is stratified and then mixed, and (c) the I2 adsorption onto, and desorption from, the vessel walls in the presence and absence of wall condensation. The codes applied by the THAI Circle partners were the Accident Source Term Evaluation Code (ASTEC)-IODE (IRSN, Saint Paul Lez Durance, France), Containment Code System (COCOSYS)-Advanced Iodine Model (AIM) (GRS, Garching, Germany), and Library of Iodine Reactions in Containment (LIRIC; AECL, Chalk River, ON, Canada). ASTEC-IODE and the Advanced Iodine Model (AIM) are semi-empirical iodine models integrated in the lumped-parameter codes ASTEC and COCOSYS, respectively. With both codes multicompartment iodine calculations can be performed. LIRIC is a mechanistic iodine model for single stand-alone calculations. The simulation results are compared with each other and with the experimental measurements. Special issues that were encountered during this work were studied in more details: I2 diffusion in the sump water, I2 reaction with the steel of the vessel wall in gaseous and aqueous phases, and I2 mass transfer from the gas to the sump. Iodine transport and behavior in THAI test Iod-9 are fairly well simulated by ASTEC-IODE, COCOSYS-AIM, and LIRIC in post-test calculations. The measured iodine behavior is well understood and all measured data are found to be consistent. The very slow iodine transport within the stratified main sump was simulated with COCOSYS only, in a qualitative way. Consequently, this work highlighted the need to improve modeling of (a) the wet iodine adsorption and the washdown from the walls, (b) the I2 mass transfer between gas and sump, and (c) the I2/steel reaction in the gaseous and aqueous phases. In any case, the analysis of the large-scale iodine test Iod-9 has been an important validation step for the codes applied.

ASTEC, COCOSYS, and LIRIC Interpretation of the Iodine Behaviour in the Large-Scale THAI Test Iod-9

2009 ◽  
Author(s):  
G. Weber ◽  
L. Bosland ◽  
F. Funke ◽  
G. Glowa ◽  
T. Kanzleiter
Keyword(s):  
Mass Transfer ◽  
Large Scale ◽  
Molecular Iodine ◽  
Measured Data ◽  
Lumped Parameter ◽  
Post Test ◽  
Iodine Test ◽  
Iodine Transport ◽  
Semi Empirical ◽  
Water Gas

The large-scale iodine test Iod-9 of the German THAI programme was jointly interpreted by means of post-test analyses within the THAI Circle of the SARNET/WP16. In this test, molecular iodine (I2) was injected into the vessel dome of the 60 m3 THAI vessel to observe the evolution of its distribution between water, gas, and surfaces. The main processes addressed in Iod-9 are (a) mass transfer of I2 between the gas and the two sumps, (b) iodine transport in the main sump when it is stratified and then mixed, and (c) I2 adsorption onto, and desorption from, the vessel walls in the presence and absence of wall condensation. The codes applied by the THAI Circle partners were ASTEC-IODE (IRSN), COCOSYS-AIM (GRS) and LIRIC (AECL). IODE and AIM are semi-empirical iodine models integrated in the lumped-parameter codes ASTEC and COCOSYS respectively. With both codes multi-compartment iodine calculations can be performed. LIRIC is a mechanistic iodine model for single stand-alone calculations. The simulation results are compared with each other and with the experimental measurements. Special issues that were encountered during this work were studied in more detail: I2 diffusion in the sump water, I2 reaction with the steel of the vessel wall in gaseous and aqueous phases, and I2 mass transfer from the gas to the sump. Iodine transport and behaviour in THAI test Iod-9 are fairly well simulated by ASTEC-IODE, COCOSYS-AIM and LIRIC in post-test calculations. The measured iodine behaviour is well understood and all measured data are found to be consistent. The very slow iodine transport within the stratified main sump was simulated with COCOSYS only, in a qualitative way. Consequently, this work highlighted the need to improve modelling of (a) the wet iodine adsorption and the washdown from the walls, (b) the I2 mass transfer between gas and sump, and (c) the I2/steel reaction in the gaseous and aqueous phases. In any case, the analysis of the large-scale iodine test Iod-9 has been an important validation step for the codes applied.

Analysis With ART Code for Adsorption of Molecular Iodine Onto Aerosols During Severe Accidents

2014 ◽  
Author(s):  
Jun Ishikawa ◽  
Yu Maruyama
Keyword(s):  
Size Distribution ◽  
Surface Area ◽  
Vessel Wall ◽  
Molecular Iodine ◽  
Severe Accident ◽  
Radioactive Materials ◽  
Surface Areas ◽  
Severe Accidents ◽  
Test Vessel ◽  
Airborne Concentration

Two tests performed in the THAI-2 project of the OECD/NEA on the adsorption of molecular iodine onto chemically inactive and active aerosols were analyzed with ART code for analysis of transportation of radioactive materials during a severe accident in order mainly to estimate adsorption velocities of I2 onto the aerosols. The results of the analysis for aerosol characteristics including airborne concentration and size distribution were reasonably agreed with the measured tendencies. The total surface areas of the aerosols, contributing to physisorption and chemisorption of I2, were evaluated to be comparable with the surface area of the THAI test vessel wall. It was found that, giving the adsorption velocity onto aerosol at 10−5 through 10−4 m/s, the decreasing tendency in the airborne concentration of I2 was well reproduced for the test with chemically inactive aerosol. The present analysis also indicated that the adsorption velocity in the test with chemically active aerosol was estimated to be larger than that in the test with chemically inactive aerosol by two orders.

First Experiments at the CIGMA Facility for Investigations of LWR Containment Thermal Hydraulics

2016 ◽  
Author(s):  
Yasuteru Sibamoto ◽  
Satoshi Abe ◽  
Masahiro Ishigaki ◽  
Taisuke Yonomoto
Keyword(s):  
Nuclear Power ◽  
Steam Injection ◽  
Light Water Reactor ◽  
Thermal Hydraulics ◽  
Japan Atomic Energy Agency ◽  
Power Station ◽  
Experimental Conditions ◽  
Energy Agency ◽  
Severe Accidents ◽  
External Cooling

There has been an extensive reorientation of the light water reactor (LWR) research in Japan since the Fukushima Dai-ichi nuclear power station (NPS) accident, which focuses on severe accidents and accident managements. The Japan Atomic Energy Agency (JAEA) initiated the ROSA-SA project in 2013 for the purpose of studying thermal hydraulics relevant to over-temperature containment damage, hydrogen risk, and fission product transport. For this purpose, the JAEA newly constructed the Containment InteGral Measurement Apparatus (CIGMA) in 2015 for the experiments addressing containment responses, separate effects, and accident managements. Recently, we successfully conducted first experiments using CIGMA to characterize the facility under typical experimental conditions investigating basic phenomena such as buildup of pressure by steam injection, containment cooling and depressurization by internal or external cooling, and density stratified layer mixing by impinging jet. This paper provides an overview of the research programs, the brief description of the facility specification and the outcomes obtained from the first experiments.

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