Idaho National Engineering Research Articles

Thermo-mechanical behavior of an ablated reactor pressure vessel wall in a Nordic BWR under in-vessel core melt retention

The reactor pressure vessel (RPV) of a nuclear reactor is one of the key safety barriers preventing radioactive environmental releases during a severe accident. One of the promising strategies of severe accident management (SAM) is to retain the molten core having continuous decay heat inside the RPV by natural water cooling of the external vessel surface. The feasibility of such a strategy relies on complex safety analyses including accurate prediction of vessel thermo-mechanical behavior which can be assessed by mechanical stresses and strains.In this paper, we present the stress–strain response of an ablated RPV of a Nordic boiling water reactor (BWR) to dynamic thermomechanical loads set by expanding volumetrically heated molten pool inside the RPV cooled by water at the external surface. MELCOR 2.2.9541 severe accident code is used to simulate the in-vessel behavior and provides the input conditions for dedicated structural analysis of the RPV using ANSYS® Mechanical APDL 19.2. A creep model of the SA533B1 vessel steel is validated against uniaxial creep tests carried out by INEL (Idaho National Engineering Laboratory) and creep tests performed at CEA (French Alternative Energies and Atomic Energy Commission) as part of the OLHF (OECD Lower Head Failure) Project. Two generic severe accident scenarios are considered: (i) Station Blackout (SBO) and (ii) Station Black-out and Loss-of-coolant Accident (SBO + LOCA). In both scenarios, we found that the RPV has maintained structural integrity considering two failure criteria: stress-based and strain-based.

Fenômeno de meandro do vento e a função de autocorrelação calculada com base na concentração de poluentes simulada pelo modelo transiente 3D-GILTT

The aim of this work is to present a pollutants dispersion transient model in low wind conditions to simulate the behavior of the pollutants plume in the atmosphere, considering in the model the u e v horizontal wind components simulated by the LES-PALM model. The dispersion model is based in the advection-diffusion equation and represent by this methodology the wind meandering phenomenon. The Generalized Integral Laplace Transform Technique in three dimensions (3D- GILTT) solves the transient advection-diffusion equation. The data utilized to initialize the simulations are data of the low wind INEL (Idaho National Engineering Laboratory) experiment accomplished in EUA. The results show that the dispersion model reproduces the wind meandering phenomenon, in other words, the autocorrelation function of the concentration simulated over an hour presents the negative lobule, similarly to observed lobules in the u and v wind components. Therefore, the model simulates the pollutants plume in a satisfactory way and can be used to air quality regulatory applications in low wind and wind meandering conditions.

Simulation of three-dimensional transient pollutant dispersion in low wind conditions using the 3D-GILTT technique

The aim of this work is to present a transient model in low wind conditionsto simulate the pollutants dispersion in the atmosphere. The dispersion model is based in the advection-diffusion equation and it considers the zonal and meridional components of the wind. The transient advection-diffusion equation is solved using integral transform techniques. In this work, the generalized integral transform and Laplace techniques are used, known in the literature as GILTT and which applied to the three-dimensional problem is called 3D-GILTT (Three-dimensional Generalized Integral Laplace Transform Technique). To validate the model, data from INEL experiment (Idaho National Engineering Laboratory) carried out in the USA were used. The model simulates the observed concentrations in a satisfactory way and can be used for regulatory air quality applications

Development and application of a system analysis code for liquid fueled molten salt reactors based on RELAP5 code

The molten salt reactor (MSR) is one of the six advanced reactor concepts declared by the Generation IV International Forum (GIF), which can be characterized by attractive attributes as inherent safety, economical efficiency, natural resource protection, sustainable development and nuclear non-proliferation. It is important to make system safety analysis for nuclear power plant of MSR. In this paper, in order to developing a system analysis code suitable for liquid fueled molten salt reactors, the point kinetics and thermo-hydraulic models as well as the numerical method in thermal–hydraulic transient code Reactor Excursion and Leak Analysis Program (RELAP5) developed at the Idaho National Engineering Laboratory (INEL) for the U.S. Nuclear Regulatory Commission (NRC) are extended and verified by Molten Salt Reactor Experiment (MSRE) experimental benchmarks. And then, four transient scenarios including the load demand change, the primary flow transient, the secondary flow transient and the reactivity transient of the Molten Salt Breeder Reactor (MSBR) are modeled and simulated so as to evaluate the performance of the reactor during the anticipated transient events using the extended RELAP5 code. The results indicate the extended RELAP5 code is effective and well suited to the liquid fueled molten salt reactor, and the MSBR has strong inherent safety characteristics because of its large negative reactivity coefficient. In the future, the extended RELAP5 code will be used to perform transient safety analysis for a liquid fueled thorium molten salt reactor named TMSR-LF developed by the Center for Thorium Molten Salt Reactor System, Chinese Academy of Sciences.

A General Lagrangian Approach to Simulate Pollutant Dispersion in Atmosphere for Low-wind Condition

In this work we present a semi-analytical Lagrangian particle model to simu late the pollutant dispersion during low wind speed conditions. The model is based on a methodology, which solves the Langevin equation through the assumption that coefficient of the integrating factor is a complex function. The method leads to a non-linear stochastic integral equation, which is solved by the Method of Successive Approximations or Picard's Iterat ive Method. Taking into account the isomorphis m between the co mp lex and real p lane by writing down the low wind fo rmulat ion in polar form, the procedure allow to determine a formu la for the lo w wind direction. Furthermo re, an exp ression analogous to the Eulerian autocorrelation function suggested by Frenkiel(1) appears in the real co mponent solution. The model results present an improvement in relat ion to the other models and are shown to agree very well with the field tracer data collected during stable conditions at Idaho National Engineering Laboratory (INEL).

A point‐source reconstruction from concentration measurements in low‐wind stable conditions

AbstractAn inversion technique is proposed to reconstruct an elevated point emission source of known height of atmospheric trace species from a finite number of concentration measurements in low‐wind stable conditions. Observations from the SF6 diffusion experiment at Idaho National Engineering Laboratory in low‐wind stable conditions are used for the point source reconstruction.The source location and its strength are both retrieved exactly with the model‐generated measurements in all the runs. With real data, the location is reconstructed with an average error of 20 m, mostly along the wind, and the intensity is retrieved within a factor of 2 in all the runs. The incurred errors in the retrieval are justified by estimating the angular departure between the vectors of measurement and adjoint function. A sensitivity study is carried out to analyse the sensitivity of the source estimation with respect to signal perturbation caused by the background concentration of the species in the ambient air. Source reconstruction is shown to be improved and more focused when the samplers having a measurement value corresponding to the background concentration are maintained in the inversion process. Copyright © 2012 Royal Meteorological Society

Assessment of a RELAP5 model for the IPR-R1 TRIGA research reactor

RELAP5 code was developed at the Idaho National Environmental and Engineering Laboratory and it is widely used for thermal hydraulic studies of commercial nuclear power plants and, currently, it has been also applied for thermal hydraulic analysis of nuclear research systems with good predictions. This work is a contribution to the assessment of RELAP5/3.3 code for research reactors analysis. It presents steady-state and transient calculation results performed using a RELAP5 model to simulate the IPR-R1 TRIGA research reactor conditions operating at 50 and 100 kW. The reactor is located at the Nuclear Technology Development Centre (CDTN), Brazil. The development and the assessment of a RELAP5 model for the IPR-R1 TRIGA are presented. Experimental data were considered in the process of code-to-data validation. The RELAP5 results were also compared with calculation performed using the STHIRP-1 (Research Reactors Thermal Hydraulic Simulation) code. The use of a cross flow model has been essential to improve results in the transient condition respect to preceding investigations.

Difusão de contaminantes em condições de vento fraco empregando um modelo estocástico Lagrangeano

Um modelo estocástico Lagrangeano é utilizado para simular a dispersão e o transporte de contaminantes, sob condições estáveis, com velocidade do vento fraco, no experimento traçante realizado no Idaho National Engineering Laboratory (INEL). Neste trabalho é testada uma nova parametrização dos parâmetros que representam as freqüências associadas ao fenômeno de meandro do vento, presentes nas equações de Langevin para as componentes do vento horizontal. Esta nova parametrização é descrita em termos de uma quantidade adimensional que controla a freqüência de oscilação de meandro do vento e da escala de tempo, associada às estruturas coerentes em uma turbulência bem desenvolvida. As simulações demonstram que o modelo Lagrangeano considerado, incorporando esta nova parametrização, reproduz corretamente a difusão de escalares passivos em uma camada limite atmosférica estável com velocidade do vento fraco.

Simulation of pollutant dispersion for low wind conditions in stable and convective planetary boundary layer

The present study proposes a steady-state mathematical model for dispersion of contaminants in low winds that takes into account the along-wind diffusion, but it does not consider the variable wind direction typical of low wind. The solution of the advection–diffusion equation for these conditions is obtained applying the generalized integral Laplace transform technique (GILTT) method and the eddy diffusivities are functions of distance from the source. The performance of the model was evaluated against the field experiments at the Idaho National Engineering Laboratory, the Lilleström dataset and during convective conditions at the Indian Institute of Technology.

Tracer dispersion simulation in low wind speed conditions with a new 2D Langevin equation system

The simulation of atmospheric dispersion in low wind speed conditions (LW) is still recognised as a challenge for modellers. Recently, a new system of two coupled Langevin equations that explicitly accounts for meandering has been proposed. It is based on the study of turbulence and dispersion properties in LW. The new system was implemented in the Lagrangian stochastic particle models LAMBDA and GRAL. In this paper we present simulations with this new approach applying it to the tracer experiments carried out in LW by Idaho National Engineering Laboratory (INEL, USA) in 1974 and by the Graz University of Technology and CNR-Torino near Graz in 2003. To assess the improvement obtained with the present model with respect to previous models not taking into account the meandering effect, the simulations for the INEL experiments were also performed with the old version of LAMBDA. The results of the comparisons clearly indicate that the new approach improves the simulation results.

MCNP Modeling Results for Location of Buried TRU Waste Drums

In the 1960's, fifty-five gallon drums of TRU waste were buried in shallow pits on remote U.S. Government facilities such as the Idaho National Engineering Laboratory (now split into the Idaho National Laboratory and the Idaho Completion Project [ICP]). Subsequently, it was decided to remove the drums and the material that was in them from the burial pits and send the material to the Waste Isolation Pilot Plant in New Mexico. Several technologies have been tried to locate the drums non-intrusively with enough precision to minimize the chance for material to be spread into the environment. One of these technologies is the placement of steel probe holes in the pits into which wireline logging probes can be lowered to measure properties and concentrations of material surrounding the probe holes for evidence of TRU material. There is also a concern that large quantities of volatile organic compounds (VOC) are also present that would contaminate the environment during removal. In 2001, the Idaho National Engineering and Environmental Laboratory (INEEL) built two pulsed neutron wireline logging tools to measure TRU and VOC around the probe holes. The tools are the Prompt Fission Neutron (PFN) and the Pulsed Neutron Gamma (PNG), respectively. They were tested experimentally in surrogate test holes in 2003. The work reported here estimates the performance of the tools using Monte-Carlo modelling prior to field deployment. A MCNP model was constructed by INEEL personnel. It was modified by the authors to assess the ability of the tools to predict quantitatively the position and concentration of TRU and VOC materials disposed around the probe holes. The model was used to simulate the tools scanning the probe holes vertically in five centimetre increments. A drum was included in the model that could be placed near the probe hole and at other locations out to forty-five centimetres from the probe-hole in five centimetre increments. Scans were performed with no chlorine in the earth around the probe hole and with three concentrations of chlorine. The PFN is configured with two detectors, and therefore data from the scans can be used to gauge the approximate distance of a drum from the probe-hole. The PNG uses ratios of gamma-ray intensities from a specific element to estimate the quantitative distance to the drum. Moreover, the PNG can distinguish VOC materials in the formation from those in the drum if there is sufficient contrast in the concentrations. The PNG and PFN can be used together to assist in planning the safe removal of contaminated materials, both TRU and VOC.

Evaluation of cerium(IV) catalyzed remediation of plutonium contaminated soils at the Idaho Cleanup Project

SummaryAn engineering and analytical chemical program was used to evaluate a proposed process to remove plutonium from contaminated soils at the Department of Energy's Idaho National Engineering and Environmental Laboratory Site. The design was based on the premise that the chemical process would be extremely efficient, reducing up to 250 nCi/g total transuranic contamination including both plutonium, in several chemical forms, and americium to less than 10 nCi/g. To ensure the effectiveness of the process on even heat-treated forms of plutonium, a very aggressive cerium IV catalyzed hot nitric acid leach step was used. Laboratory experiments showed that the chemistry could indeed remove plutonium, but due to the secondary wastes generated by coincident dissolution of the soil matrix, the process did not meet other design requirements.

Molecular characterization of microbial populations at two sites with differing reductive dechlorination abilities

This study compares three molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP), RFLP analysis with clone sequencing, and quantitative PCR (Q-PCR) for surveying differences in microbial communities at two contaminated field sites that exhibit dissimilar chlorinated solvent degradation activities. At the Idaho National Engineering and Environmental Laboratory (INEEL), trichloroethene (TCE) was completely converted to ethene during biostimulation with lactate. At Seal Beach, California, perchloroethene (PCE) was degraded only to cis-dichloroethene (cDCE) during biostimulation but was degraded to ethene after bioaugmentation with a dechlorinating culture containing Dehalococcoides strains. T-RFLP analysis showed that microbial community composition differed significantly between the two sites, but was similar within each site among wells that had low or no electron donor exposure. Analysis of INEEL clone libraries by RFLP with clone sequencing revealed a complex microbial population but did not identify any Dehalococcoides strains. Q-PCR targeting the 16S rRNA gene of Dehalococcoides strains - known for their unique capability to dechlorinate solvents completely to ethene - revealed a significant population at INEEL, but no detectable population at Seal Beach prior to bioaugmentation. Detection of Dehalococcoides by Q-PCR correlated with observed dechlorination activity and ethene production at both sites. Q-PCR showed that Dehalococcoides was present in even the pristine well at INEEL, suggesting that the difference in dechlorination ability at the two sites was due to the initial absence of this genus at Seal Beach. Of the techniques tested, Q-PCR quantification of specific dechlorinating species provided the most effective and direct prediction of community dechlorinating potential.

Assessment of RELAP5 model for the University of Massachusetts Lowell Research Reactor

RELAP5 is a system code developed at the Idaho National Environmental and Engineering Laboratory for thermal hydraulic analysis of nuclear reactors. The code RELAP5 is widely used for safety analysis studies of commercial nuclear power plants. However, recent released version of RELAP5/3.2 and over present significant capabilities for analysis of nuclear reactor research systems. As a contribution to the assessment of RELAP5/3.3 for research reactor safety analysis, experimental data from the University of Massachusetts Lowell Research Reactor - UMLRR are used. The UMLRR is a 1 MW light water moderated and cooled, graphite-reflected, open-pool type research reactor. This paper presents the development and the validation of a UMLRR-RELAP model using experimental data. For this purpose, a series of experiments were performed for benchmarking RELAP5 calculations for research reactor systems. As a result of this study, the UMLRR nodalization is shown to be representative of the experimental data reactor behavior.

Enhanced anaerobic bioremediation in a DNAPL residual source zone: Test Area North case study

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on case studies in which bioremediation of dense nonaqueous-phase liquids (DNAPLs) was performed. This first case study, the Test Area North (TAN) site of the Idaho National Engineering and Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999. Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source. Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL. © 2006 Wiley Periodicals, Inc.

MAMMAL ABUNDANCE INDICES IN THE NORTHERN PORTION OF THE GREAT BASIN, 1962–1993

Indices of abundance of selected mammals were obtained for two study areas within the Great Basin: the Idaho National Engineering and Environmental Laboratory, Idaho, and Curlew Valley, Utah, USA. Data collection occurred biannually 1962–1993, with varying durations among species and sites. Abundance indices were obtained for coyotes (Canis latrans), lagomorphs (primarily black-tailed jackrabbits, Lepus californicus), and eight species of rodents. Data were originally gathered as part of a long-term study of interactions among predator and prey populations, concentrating on aspects related to coyotes and black-tailed jackrabbits. Secondarily, these data are useful in portraying trends in mammal abundance on these two Great Basin sites.

Pollutant dispersion simulation for low wind speed condition by the ILS method

A semi-analytical Lagrangian particle model to simulate the pollutant dispersion during low wind speed conditions is presented and tested. The method relies to a stochastic integral equation whose solution is obtained using ILS method, which consists in the iterative solution of Langevin equation by the Picard's iteration method. To consider the low wind speed effect, the solution for the horizontal components of the turbulent velocity takes account the Eulerian autocorrelation function as suggested by Frenkiel [1953. Advances in Applied Mechanics 3, 61–107]. The model results are shown to agree very well with the field tracer data collected during stable conditions at Idaho National Engineering Laboratory (INEL) and during convective conditions from the series of field experiments at Indian Institute of Technology (IIT). A statistical analysis reveals that the model simulates very well the experimental data and presents results comparable or even better than ones obtained with other models used as comparison. The analytical feature of the ILS method and the inclusion of the Eulerian autocorrelation function suggested by Frenkiel (1953) allow generating more accurate results.

System Dynamics Modeling of Transboundary Systems: The Bear River Basin Model

System dynamics is a computer-aided approach to evaluating the interrelationships of different components and activities within complex systems. Recently, system dynamics models have been developed in areas such as policy design, biological and medical modeling, energy and the environmental analysis, and in various other areas in the natural and social sciences. The Idaho National Engineering and Environmental Laboratory, a multipurpose national laboratory managed by the Department of Energy, has developed a system dynamics model in order to evaluate its utility for modeling large complex hydrological systems. We modeled the Bear River basin, a transboundary basin that includes portions of Idaho, Utah, and Wyoming. We found that system dynamics modeling is very useful for integrating surface water and ground water data and for simulating the interactions between these sources within a given basin. In addition, we also found that system dynamics modeling is useful for integrating complex hydrologic data with other information (e.g., policy, regulatory, and management criteria) to produce a decision support system. Such decision support systems can allow managers and stakeholders to better visualize the key hydrologic elements and management constraints in the basin, which enables them to better understand the system via the simulation of multiple "what-if" scenarios. Although system dynamics models can be developed to conduct traditional hydraulic/hydrologic surface water or ground water modeling, we believe that their strength lies in their ability to quickly evaluate trends and cause-effect relationships in large-scale hydrological systems, for integrating disparate data, for incorporating output from traditional hydraulic/hydrologic models, and for integration of interdisciplinary data, information, and criteria to support better management decisions.

Storage and Assay of Tritium in STAR

The Safety and Tritium Applied Research (STAR) facility at the Idaho National Engineering and Environmental Laboratory (INEEL) is currently being commissioned to investigate tritium-related safety questions for fusion and other technologies. The tritium inventory for the STAR facility will be maintained below 1.5 g to avoid the need for STAR to be classified as a Category 3 nuclear facility. A key capability in successful operation of the STAR facility is the ability to receive, inventory, and dispense tritium to the various experiments underway there. The system central to that function is the Tritium Storage and Assay System (SAS).The SAS has four major functions: (1) receiving and holding tritium, (2) assaying, (3) dispensing, and (4) purifying hydrogen isotopes from non-hydrogen species.This paper describes the design and operation of the STAR SAS and the procedures used for tritium accountancy in the STAR facility.

The Safety and Tritium Applied Research (STAR) Facility: Status-2004

The Safety and Tritium Applied Research (STAR) Facility, a US DOE National User Facility at the Idaho National Engineering and Environmental Laboratory (INEEL), comprises capabilities and infrastructure to support both tritium and non-tritium research activities important to the development of safe and environmentally friendly fusion energy. Research thrusts include (1) interactions of tritium and deuterium with plasma-facing-component (PFC) materials, (2) fusion safety issues [PFC material chemical reactivity and dust/debris generation, activation product mobilization, tritium behavior in fusion systems], and (3) molten salts and fusion liquids for tritium breeder and coolant applications. This paper updates the status of STAR and the capabilities for ongoing research activities, with an emphasis on the development, testing and integration of the infrastructure to support tritium research activities. Key elements of this infrastructure include a tritium storage and assay system, a tritium cleanup system to process glovebox and experiment tritiated effluent gases, and facility tritium monitoring systems.