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Transient Accident Analysis of the Glovebox System in a Large Process Room

Description: Local transient hydrogen concentrations were evaluated inside a large process room when the hydrogen gas was released by three postulated accident scenarios associated with the process tank leakage and fire leading to a loss of gas confinement. The three cases considered in this work were fire in a room, loss of confinement from a process tank, and loss of confinement coupled with fire event. Based on these accident scenarios in a large and unventilated process room, the modeling calculations of the hydrogen migration were performed to estimate local transient concentrations of hydrogen due to the sudden leakage and release from a glovebox system associated with the process tank. The modeling domain represented the major features of the process room including the principal release or leakage source of gas storage system. The model was benchmarked against the literature results for key phenomena such as natural convection, turbulent behavior, gas mixing due to jet entrainment, and radiation cooling because these phenomena are closely related to the gas driving mechanisms within a large air space of the process room. The modeling results showed that at the corner of the process room, the gas concentrations migrated by the Case 2 and Case 3 scenarios reached the set-point value of high activity alarm in about 13 seconds, while the Case 1 scenario takes about 90 seconds to reach the concentration. The modeling results were used to estimate transient radioactive gas migrations in an enclosed process room installed with high activity alarm monitor when the postulated leakage scenarios are initiated without room ventilation.
Date: January 11, 2008
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

GROUT HOPPER MODELING STUDY

Description: The Saltstone facility has a grout hopper tank to provide agitator stirring of the Saltstone feed materials. The tank has about 300 gallon capacity to provide a larger working volume for the grout slurry to be held in case of a process upset, and it is equipped with a mechanical agitator, which is intended to keep the grout in motion and agitated so that it won't start to set up. The dry feeds and the salt solution are already mixed in the mixer prior to being transferred to the hopper tank. The hopper modeling study through this work will focus on fluid stirring and agitation, instead of traditional mixing in the literature, in order to keep the tank contents in motion during their residence time so that they will not be upset or solidified prior to transferring the grout to the Saltstone disposal facility. The primary objective of the work is to evaluate the flow performance for mechanical agitators to prevent vortex pull-through for an adequate stirring of the feed materials and to estimate an agitator speed which provides acceptable flow performance with a 45{sup o} pitched four-blade agitator. In addition, the power consumption required for the agitator operation was estimated. The modeling calculations were performed by taking two steps of the Computational Fluid Dynamics (CFD) modeling approach. As a first step, a simple single-stage agitator model with 45{sup o} pitched propeller blades was developed for the initial scoping analysis of the flow pattern behaviors for a range of different operating conditions. Based on the initial phase-1 results, the phase-2 model with a two-stage agitator was developed for the final performance evaluations. A series of sensitivity calculations for different designs of agitators and operating conditions have been performed to investigate the impact of key parameters on the grout hydraulic performance ...
Date: August 30, 2011
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

TANK48 CFD MODELING ANALYSIS

Description: The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitative mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions ...
Date: May 17, 2011
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

MODELING ANALYSIS FOR GROUT HOPPER WASTE TANK

Description: The Saltstone facility at Savannah River Site (SRS) has a grout hopper tank to provide agitator stirring of the Saltstone feed materials. The tank has about 300 gallon capacity to provide a larger working volume for the grout nuclear waste slurry to be held in case of a process upset, and it is equipped with a mechanical agitator, which is intended to keep the grout in motion and agitated so that it won't start to set up. The primary objective of the work was to evaluate the flow performance for mechanical agitators to prevent vortex pull-through for an adequate stirring of the feed materials and to estimate an agitator speed which provides acceptable flow performance with a 45{sup o} pitched four-blade agitator. In addition, the power consumption required for the agitator operation was estimated. The modeling calculations were performed by taking two steps of the Computational Fluid Dynamics (CFD) modeling approach. As a first step, a simple single-stage agitator model with 45{sup o} pitched propeller blades was developed for the initial scoping analysis of the flow pattern behaviors for a range of different operating conditions. Based on the initial phase-1 results, the phase-2 model with a two-stage agitator was developed for the final performance evaluations. A series of sensitivity calculations for different designs of agitators and operating conditions have been performed to investigate the impact of key parameters on the grout hydraulic performance in a 300-gallon hopper tank. For the analysis, viscous shear was modeled by using the Bingham plastic approximation. Steady state analyses with a two-equation turbulence model were performed. All analyses were based on three-dimensional results. Recommended operational guidance was developed by using the basic concept that local shear rate profiles and flow patterns can be used as a measure of hydraulic performance and spatial stirring. Flow patterns ...
Date: January 4, 2012
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

MIXING STUDY FOR JT-71/72 TANKS

Description: All modeling calculations for the mixing operations of miscible fluids contained in HBLine tanks, JT-71/72, were performed by taking a three-dimensional Computational Fluid Dynamics (CFD) approach. The CFD modeling results were benchmarked against the literature results and the previous SRNL test results to validate the model. Final performance calculations were performed by using the validated model to quantify the mixing time for the HB-Line tanks. The mixing study results for the JT-71/72 tanks show that, for the cases modeled, the mixing time required for blending of the tank contents is no more than 35 minutes, which is well below 2.5 hours of recirculation pump operation. Therefore, the results demonstrate the adequacy of 2.5 hours’ mixing time of the tank contents by one recirculation pump to get well mixed.
Date: November 26, 2013
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

THERMAL MODELING ANALYSIS OF CST MEDIA IN THE SMALL COLUMN ION EXCHANGE PROJECT

Description: Models have been developed to simulate the thermal characteristics of Crystalline Silicotitanate (CST) ion exchange media fully loaded with radioactive cesium in a column configuration and distributed within a waste storage tank. This work was conducted to support the Small Column Ion Exchange (SCIX) program which is focused on processing dissolved, high-sodium salt waste for the removal of specific radionuclides (including Cs-137, Sr-90, and actinides) within a High Level Waste (HLW) storage tank at the Savannah River Site. The SCIX design includes CST columns inserted and supported in the tank top risers for cesium removal. Temperature distributions and maximum temperatures across the column were calculated with a focus on process upset conditions. A two-dimensional computational modeling approach for the in-column ion-exchange domain was taken to include conservative, bounding estimates for key parameters such that the results would provide the maximum centerline temperatures achievable under the design configurations using a feed composition known to promote high cesium loading on CST. One salt processing scenario includes the transport of the loaded (and possibly ground) CST media to the treatment tank floor. Therefore, additional thermal modeling calculations were conducted using a three-dimensional approach to evaluate temperature distributions for the entire in-tank domain including distribution of the spent CST media either as a mound or a flat layer on the tank floor. These calculations included mixtures of CST with HLW sludge or loaded Monosodium Titanate (MST) media used for strontium/actinide sorption. The current full-scale design for the CST column includes one central cooling pipe and four outer cooling tubes. Most calculations assumed that the fluid within the column was stagnant (i.e. no buoyancy-induced flow) for a conservative estimate. A primary objective of these calculations was to estimate temperature distributions across packed CST beds immersed in waste supernate or filled with dry air under various ...
Date: November 1, 2010
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

BLENDING ANALYSIS FOR RADIOACTIVE SALT WASTE PROCESSING FACILITY

Description: Savannah River National Laboratory (SRNL) evaluated methods to mix and blend the contents of the blend tanks to ensure the contents are properly blended before they are transferred from the blend tank such as Tank 21 and Tank 24 to the Salt Waste Processing Facility (SWPF) feed tank. The tank contents consist of three forms: dissolved salt solution, other waste salt solutions, and sludge containing settled solids. This paper focuses on developing the computational model and estimating the operation time of submersible slurry pump when the tank contents are adequately blended prior to their transfer to the SWPF facility. A three-dimensional computational fluid dynamics approach was taken by using the full scale configuration of SRS Type-IV tank, Tank 21H. Major solid obstructions such as the tank wall boundary, the transfer pump column, and three slurry pump housings including one active and two inactive pumps were included in the mixing performance model. Basic flow pattern results predicted by the computational model were benchmarked against the SRNL test results and literature data. Tank 21 is a waste tank that is used to prepare batches of salt feed for SWPF. The salt feed must be a homogeneous solution satisfying the acceptance criterion of the solids entrainment during transfer operation. The work scope described here consists of two modeling areas. They are the steady state flow pattern calculations before the addition of acid solution for tank blending operation and the transient mixing analysis during miscible liquid blending operation. The transient blending calculations were performed by using the 95% homogeneity criterion for the entire liquid domain of the tank. The initial conditions for the entire modeling domain were based on the steady-state flow pattern results with zero second phase concentration. The performance model was also benchmarked against the SRNL test results and literature data.
Date: May 10, 2012
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

JET MIXING ANALYSIS FOR SRS HIGH-LEVEL WASTE RECOVERY

Description: The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four slurry pumps located within the tank liquid. The slurry pump may be fixed in position or they may rotate depending on the specific mixing requirements. The high-level waste in Tank 48 contains insoluble solids in the form of potassium tetraphenyl borate compounds (KTPB), monosodium titanate (MST), and sludge. Tank 48 is equipped with 4 slurry pumps, which are intended to suspend the insoluble solids prior to transfer of the waste to the Fluidized Bed Steam Reformer (FBSR) process. The FBSR process is being designed for a normal feed of 3.05 wt% insoluble solids. A chemical characterization study has shown the insoluble solids concentration is approximately 3.05 wt% when well-mixed. The project is requesting a Computational Fluid Dynamics (CFD) mixing study from SRNL to determine the solids behavior with 2, 3, and 4 slurry pumps in operation and an estimate of the insoluble solids concentration at the suction of the transfer pump to the FBSR process. The impact of cooling coils is not considered in the current work. The work consists of two principal objectives by taking a CFD approach: (1) To estimate insoluble solids concentration transferred from Tank 48 to the Waste Feed Tank in the FBSR process and (2) To assess the impact of different combinations of four slurry pumps on insoluble solids suspension and mixing in Tank 48. For this work, several different combinations of a maximum of four pumps are considered to determine the resulting flow patterns and local flow velocities which are thought to be associated with sludge particle mixing. Two different elevations of pump nozzles are used for ...
Date: July 5, 2011
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

TRANSIENT HEAT TRANSFER ANALYSIS FOR SRS RADIOACTIVE TANK OPERATION

Description: The primary objective of the present work is to perform a heat balance study for type-I waste tank to assess the impact of using submersible mixer pumps during waste removal. The temperature results calculated by the model will be used to evaluate the temperatures of the slurry waste under various tank operating conditions. A parametric approach was taken to develop a transient model for the heat balance study for type-I waste tanks such as Tank 11, during waste removal by SMP. The tank domain used in the present model consists of two SMP�s for sludge mixing, one STP for the waste removal, cooling coil system with 36 coils, and purge gas system. The sludge waste contained in Tank 11 also has a decay heat load of about 43 W/m{sup 3} mainly due to the emission of radioactive gamma rays. All governing equations were established by an overall energy balance for the tank domain, and they were numerically solved. A transient heat balance model used single waste temperature model, which represents one temperature for the entire waste liquid domain contained in the tank at each transient time.
Date: June 27, 2013
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

MIXING MODELING ANALYSIS FOR SRS SALT WASTE DISPOSITION

Description: Nuclear waste at Savannah River Site (SRS) waste tanks consists of three different types of waste forms. They are the lighter salt solutions referred to as supernate, the precipitated salts as salt cake, and heavier fine solids as sludge. The sludge is settled on the tank floor. About half of the residual waste radioactivity is contained in the sludge, which is only about 8 percentage of the total waste volume. Mixing study to be evaluated here for the Salt Disposition Integration (SDI) project focuses on supernate preparations in waste tanks prior to transfer to the Salt Waste Processing Facility (SWPF) feed tank. The methods to mix and blend the contents of the SRS blend tanks were evalutaed to ensure that the contents are properly blended before they are transferred from the blend tank such as Tank 50H to the SWPF feed tank. The work consists of two principal objectives to investigate two different pumps. One objective is to identify a suitable pumping arrangement that will adequately blend/mix two miscible liquids to obtain a uniform composition in the tank with a minimum level of sludge solid particulate in suspension. The other is to estimate the elevation in the tank at which the transfer pump inlet should be located where the solid concentration of the entrained fluid remains below the acceptance criterion (0.09 wt% or 1200 mg/liter) during transfer operation to the SWPF. Tank 50H is a Waste Tank that will be used to prepare batches of salt feed for SWPF. The salt feed must be a homogeneous solution satisfying the acceptance criterion of the solids entrainment during transfer operation. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. ...
Date: January 18, 2011
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

SDI CFD MODELING ANALYSIS

Description: The Savannah River Remediation (SRR) Organization requested that Savannah River National Laboratory (SRNL) develop a Computational Fluid Dynamics (CFD) method to mix and blend the miscible contents of the blend tanks to ensure the contents are properly blended before they are transferred from the blend tank; such as, Tank 50H, to the Salt Waste Processing Facility (SWPF) feed tank. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. The transient CFD governing equations consisting of three momentum equations, one mass balance, two turbulence transport equations for kinetic energy and dissipation rate, and one species transport were solved by an iterative technique until the species concentrations of tank fluid were in equilibrium. The steady-state flow solutions for the entire tank fluid were used for flow pattern analysis, for velocity scaling analysis, and the initial conditions for transient blending calculations. A series of the modeling calculations were performed to estimate the blending times for various jet flow conditions, and to investigate the impact of the cooling coils on the blending time of the tank contents. The modeling results were benchmarked against the pilot scale test results. All of the flow and mixing models were performed with the nozzles installed at the mid-elevation, and parallel to the tank wall. From the CFD modeling calculations, the main results are summarized as follows: (1) The benchmark analyses for the CFD flow velocity and blending models demonstrate their consistency with Engineering Development Laboratory (EDL) and literature test results in terms of local velocity measurements and experimental observations. Thus, an application of the established criterion to SRS full scale tank will provide a better, physically-based estimate of the required mixing time, and elevation of ...
Date: May 5, 2011
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

HEAT TRANSFER ANALYSIS FOR NUCLEAR WASTE SOLIDIFICATION CONTAINER

Description: The Nuclear Nonproliferation Programs Design Authority is in the design stage of the Waste Solidification Building (WSB) for the treatment and solidification of the radioactive liquid waste streams generated by the Pit Disassembly and Conversion Facility (PDCF) and Mixed Oxide (MOX) Fuel Fabrication Facility (MFFF). The waste streams will be mixed with a cementitious dry mix in a 55-gallon waste container. Savannah River National Laboratory (SRNL) has been performing the testing and evaluations to support technical decisions for the WSB. Engineering Modeling & Simulation Group was requested to evaluate the thermal performance of the 55-gallon drum containing hydration heat source associated with the current baseline cement waste form. A transient axi-symmetric heat transfer model for the drum partially filled with waste form cement has been developed and heat transfer calculations performed for the baseline design configurations. For this case, 65 percent of the drum volume was assumed to be filled with the waste form, which has transient hydration heat source, as one of the baseline conditions. A series of modeling calculations has been performed using a computational heat transfer approach. The baseline modeling results show that the time to reach the maximum temperature of the 65 percent filled drum is about 32 hours when a 43 C initial cement temperature is assumed to be cooled by natural convection with 27 C external air. In addition, the results computed by the present model were compared with analytical solutions. The modeling results will be benchmarked against the prototypic test results. The verified model will be used for the evaluation of the thermal performance for the WSB drum. Detailed results and the cases considered in the calculations will be discussed here.
Date: June 1, 2009
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

Transient Heat Transfer Analysis for Ion-Exchange Waste Removal Process

Description: The small column ion exchange (SCIX) process treats low curie salt (LCS) waste before feeding it to the saltstone facility to be made into grout. Through this process, radioactive cesium from the salt solution is absorbed into the CST bed. A CST column loaded with radioactive cesium will generate significant heat from radiolytic decay. If engineering designs of the CST sorption column can not handle this thermal load, hot spots may develop locally within the column and degrade the performance of the ion-exchange process. The CST starts to degrade at about 80 to 85 C, and the CST completely changes to another material above 120 C. In addition, the process solution will boil around 130 C. If the column boiled dry, the sorbent could plug the column and require replacement of the column module. The objective of the present work is to compute temperature distributions across the column as a function of transit time after the initiation of accidents when there is loss of the salt solution flow in the CST column under abnormal conditions of the process operations. In this situation, the customer requested that the calculations should be conservative in that the model results would show the maximum centerline temperatures achievable by the CST design configurations. The thermal analysis results will be used to evaluate the fluid temperature distributions and the process component temperatures within the ion exchange system. This information will also assist in the system design and maintenance.
Date: July 12, 2010
Creator: Lee, S.
Partner: UNT Libraries Government Documents Department

Agitator Mixing Analysis in a HB-Line Flat Tank

Description: In support of the HB-Line Engineering agitator mixing project, flow pattern calculations have been made for a 45 degrees pitched three-blade agitator submerged in a flat rectangular tank. The work is intended to determine agitator speeds that provide acceptable mixing performance for various tank liquid levels based on flow rates past solids deposited on the bottom surface of the flat tank. The modeling results will help ensure the acceptable suspension of solid particles as a function of agitator speed and tank liquid level during precipitation operations. The numerical modeling and calculations have been performed using a computational fluid dynamics approach. Three-dimensional steady-state momentum and continuity equations were used as the basic equations to estimate fluid motion driven by an agitator with three 45 degrees pitched blades. Hydraulic conditions were fully turbulent (Reynolds number about 2x104). A standard two-equation turbulence model (k-e), was used to capture turbulent eddy motion. The commercial finite volume code, Fluent [7], was used to create a prototypic geometry file with a non-orthogonal mesh. Hybrid meshing was used to fill the computational region between the round-edged tank bottom and agitator regions. At high rotational speeds and low tank levels, a surface vortex can reach the agitator blades and allow air to be drawn into the solid-fluid mixing zone. This is not desirable in terms of mixing performance. The analysis results show that the lowest liquid level among the four considered, 4.5 inches, is higher than the critical liquid height for air entrainment for agitator speeds up to 600 rpm. All the analysis results demonstrate that about 600 rpm provides adequate solids mixing capability for various tank levels (12, 8.5, 7, and 4.5 inches) containing 20-micron solids with a specific gravity of 2.5.
Date: July 31, 2002
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Heel Removal Analysis for Mixing Pumps of Tank 8

Description: Computational fluid dynamics methods were used to recommend a slurry pump operational strategy for sludge heel removal in Tank 8. Flow patterns calculated by the model were used to evaluate the performance of various combinations of operating pumps and their orientation. The models focused on removal of the sludge heel located at the east side of Tank 8 using the four existing slurry pumps. The models and calculations were based on prototypic tank geometry and expected normal operating conditions as defined by Waste Removal Closure (WRC) Engineering. The calculated results demonstrated that for pump speeds higher than 1800 rpm and at a 130 inch liquid level, a recommended orientation of the slurry pumps could be provided, based on a minimum sludge suspension velocity of 2.27 ft per sec. Further results showed that the time to reach a steady-state flow pattern was affected by both the tank level and the pump speed. Sensitivity studies showed that for a given pump speed, a higher tank level and a lower pump nozzle elevation would result in better performance in suspending and removing the sludge. The results also showed that the presence of flow obstructions were advantageous for certain pump orientations.
Date: May 21, 2003
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Analysis/control of in-bed tube erosion phenomena in the fluidized bed combustion (FBC) system. Technical progress report No. 12

Description: This technical report summarizes the research work performed and progress achieved during the period of July 1, 1995 to October 30, 1995. The characteristics of resistant coatings were determined and related to metal wastage of in-bed tubes in FBC under various laboratory test conditions, The tests were conducted at high impact velocity, 30 m/s, and short exposure time (4 hours) to minimize oxidation of surrounding surface specimens. No oxidation layer founded on the worn surfaces of AISI 1018 carbon steel, The eroded surfaces and cross sections of coatings tested at high velocity were investigated, The surfaces of coating specimens were eroded through a combined mechanism of brittle and ductile modes, These mechanical properties of materials are strongly dependent on the composition and microstate of materials, rather than to their hardness, For high velocity testing, all of the coatings exhibited {open_quotes}brittle behavior{close_quotes}, i.e., the erosion rate at shallow angles was higher than at steep angles and maximum erosion rate at impact angle of 90{degrees}. Tests will be continued and compared with erosion test results for different thermal sprayed coatings.
Date: October 1, 1995
Creator: Lee, S.W.
Partner: UNT Libraries Government Documents Department

Thermal Performance Analysis of Repository Codisposal Waste Packages Containing Aluminum-Clad Spent Nuclear Fuel

Description: The leading codisposal waste package (WP) design proposes that a central DOE Aluminum-clad Spent Nuclear Fuel (Al-SNF) canister be surrounded by five defense waste process facility (DWPF) glass log canisters, and placed into a WP in the Mined Geologic Disposal System (MGDS).
Date: February 19, 1999
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Heat Transfer Modeling of Dry Spent Nuclear Fuel Storage Facilities

Description: The present work was undertaken to provide heat transfer model that accurately predicts the thermal performance of dry spent nuclear fuel storage facilities. One of the storage configurations being considered for DOE Aluminum-clad Spent Nuclear Fuel (Al-SNF), such as the Material and Testing Reactor (MTR) fuel, is in a dry storage facility. To support design studies of storage options a computational and experimental program has been conducted at the Savannah River Site (SRS). The main objective is to develop heat transfer models including natural convection effects internal to an interim dry storage canister and to geological codisposal Waste Package (WP). Calculated temperatures will be used to demonstrate engineering viability of a dry storage option in enclosed interim storage and geological repository WP and to assess the chemical and physical behaviors of the Al-SNF in the dry storage facilities. The current paper describes the modeling approaches and presents the computational results along with the experimental data.
Date: January 13, 1999
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Investigation of heat transfer and combustion in the advanced fluidized bed combustor (FBC)

Description: This technical report summarizes the research conducted and progress achieved during the period from April 1, 1998 to June 30, 1998. The numerical simulation was continued to determine the concentration distribution of the gas species, heat flux and heat transfer coefficients in the hot combustor model. The different gas concentration profiles showed the gas mixing characteristics along the combustor height. The center zone of the combustor has a relatively high methane mass concentration. The injection of secondary air squeezes the uprising flue gas and methane that causes the fuel-lean zone near the secondary air nozzles. The carbon dioxide concentration increased with the increasing of the combustor height. The peak concentration of oxygen remains at the combustor wall because of the secondary injection. The heat flux on the wall of the upper chamber is much higher than that of the lower chamber. It is believed that the heat flux is affected by the designed strong swirl and secondary air injection. The heat transfer coefficient changes along the combustor height were also affected by the multiple secondary air injection. The numerical simulation results could verify the predictions of the experimental results. It is a quite similar trend of the heat transfer coefficient changes based on the combustion test results.
Date: September 1, 1999
Creator: Lee, S.W.
Partner: UNT Libraries Government Documents Department

Heat Transfer Calculations for Normal Operations of a Fixed CST Bed Column

Description: In support of the crystalline silicotitanate (CST) ion exchange project of High-Level Waste (HLW) Process Engineering, heat transfer calculations have been made for a fully-loaded CST column during abnormal and normal operating conditions. The objective of the present work is to compute temperature distributions across the column when there is steady flow of salt solution through the CST column under normal conditions of the process operations.
Date: September 10, 2001
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Three-dimensional Computational Fluid Dynamics (CFD) modeling of dry spent nuclear fuel storage canisters

Description: One of the interim storage configurations being considered for aluminum-clad foreign research reactor fuel, such as the Material and Testing Reactor (MTR) design, is in a dry storage facility. To support design studies of storage options, a computational and experimental program was conducted at the Savannah River Site (SRS). The objective was to develop computational fluid dynamics (CFD) models which would be benchmarked using data obtained from a full scale heat transfer experiment conducted in the SRS Experimental Thermal Fluids Laboratory. The current work documents the CFD approach and presents comparison of results with experimental data. CFDS-FLOW3D (version 3.3) CFD code has been used to model the 3-dimensional convective velocity and temperature distributions within a single dry storage canister of MTR fuel elements. For the present analysis, the Boussinesq approximation was used for the consideration of buoyancy-driven natural convection. Comparison of the CFD code can be used to predict reasonably accurate flow and thermal behavior of a typical foreign research reactor fuel stored in a dry storage facility.
Date: June 1, 1997
Creator: Lee, S.Y.
Partner: UNT Libraries Government Documents Department

Investigation of heat transfer and combustion in the Advanced Fluidized Bed Combustor (FBC). Technical progress report, April 1995--June 1995

Description: This technical report summarizes the research performed and progress achieved during the period of April 1, 1995 to June 30, 1995, The particle flow measurements on mass flux of radial directional were conducted and discussed. The particle dispersion is dense near the wall and relatively dilute in the core region. It was found that the particle mass flux generally increases along the radial direction adjacent to the wall of the test chamber. An interface at a certain radius adjacent to the chamber wall is expected where interacting forces are dynamically balanced. The dense suspension layers and the dilute suspension regions were observed in the freeboard of the exploratory cold model (6 inches I.D.). Based upon observations and measurements, the general behavior of suspension layers was summarized in this report. The bench-scale advanced FBC test chamber (10 inches I.D.) was designed and fabricated to better understand how gas recirculating flow, particle suspension flow, and particle elutriation rate are affected by swirling flow in the freeboard of the test chamber. The measurements of the gas and particle flows will be conducted in this bench-scale model.
Date: July 1, 1995
Creator: Lee, S.W.
Partner: UNT Libraries Government Documents Department

Analysis/control of in-bed tube erosion phenomena in the fluidized bed combustion (FBC) system. Technical progress report No. 8, July 1994--September 1994

Description: This technical report summarizes the research work performed and progress achieved during the period of July 1, 1994 to September 30, 1994. The metal wastage of AISI 1018 low carbon steel at different particle velocity was discussed to understand the erosion phenomena of in-bed tube in FBC system. At both low velocity (2.5 m/s) and high (30 m/s), the maximum metal wastage was occurred at 45{degrees} of impact angle. The erosion rates at low particle velocity were two (2) to three (3) orders of magnitude lower than those at high particle velocity. The characteristics of anti-erosion and design considerations were discussed and suggested for some basic design guidelines, which might be important to the designer of bubbling fluidized combustors. The working principle and mechanism of anti-erosion devices will be discussed. Based upon the understanding of the working principle and mechanism of anti-erosion devices, different types of ant-erosion tube will be designed for the cold model bench-scale FBC system.
Date: October 1, 1994
Creator: Lee, S.W.
Partner: UNT Libraries Government Documents Department