This document provides background information on a study analyzing neutron activation of heat exchangers in an I2S-LWR nuclear reactor. It discusses the integrated heat exchanger design that could lead to activation issues. The objective is to evaluate reducing heat exchanger activation by altering height, which could lower worker radiation exposure and costs. Neutron flux calculations using MCNP will analyze typical values striking heat exchanger surfaces to evaluate other design variables.
Targeted Band Structure Design and Thermoelectric Materials Discovery Using H...Anubhav Jain
This work was supported by funding from the U.S. Department of Energy and involved collaborations with researchers from Northwestern University, Universite Catholique de Louvain, Dalhousie University, and UC Berkeley/LBNL. Using high-throughput computational methods, over 50,000 compounds were screened to discover new thermoelectric materials, identifying YCuTe2 as a promising candidate with a calculated zT of 0.75. Experimental synthesis and testing achieved a maximum zT of 0.75 for this material. Future work will involve developing more accurate electronic transport models, expanding the materials library through substitutional predictions, and applying machine learning to discover new structure-property relationships.
Computational Discovery of Thermal Fluids with Enhanced Heat CapacityAnubhav Jain
(1) The document discusses a project to develop a thermal fluid with enhanced heat capacity through computational discovery of thermally activated covalent bond formation.
(2) The approach involves using computational screening of potential reactions to identify systems where heat is absorbed or released during covalent bond breaking and formation on heating and cooling, respectively.
(3) Preliminary experimental results on computationally predicted systems show heat capacity enhancements within organic solvents and water, demonstrating the potential of the approach.
The Materials Project and computational materials discoveryAnubhav Jain
1. The Materials Project aims to accelerate materials discovery through high-throughput computational screening of materials properties using density functional theory calculations.
2. Over 60,000 compounds have been computed so far, with properties including total energies, optimized structures, band structures, and elastic tensors.
3. The goal is to compute properties for over 90,000 materials to help researchers discover new materials for applications like batteries, thermoelectrics, and other energy technologies.
Application of the Materials Project database and data mining towards the des...Anubhav Jain
This document summarizes research into using high-throughput density functional theory (DFT) calculations and data mining of the Materials Project database to design new thermoelectric and functional materials. Key findings include identifying new thermoelectric materials like TmAgTe2 with a peak zT of 0.75 through screening 40,000 compounds. Preliminary analysis also began to understand how to control band structure by ranking elemental orbitals' likelihood of forming the valence band maximum and conduction band minimum. The overall goal is to accelerate materials discovery and design through computational modeling and data mining at massive scales.
Combining High-Throughput Computing and Statistical Learning to Develop and U...Anubhav Jain
This document summarizes research into developing new thermoelectric materials through high-throughput computing and statistical learning. Key points:
- Thermoelectric materials can convert heat to electricity but require high figure of merit (ZT). Computational screening of over 50,000 compounds has identified promising candidates.
- TmAgTe2 and YCuTe2 were discovered through this method and experimentally validated, with zT of 0.75 for YCuTe2.
- Bournonite materials like CuPbSbS3 have low thermal conductivity but require improved electrical properties. Over 300 substitutions were modeled to explore variations.
- Open data resources like Materials Project and tools like MatMiner being developed to enable data mining and accelerate materials
This document summarizes a study that compared a single chamber microbial fuel cell (SC-MFC) to a double chamber microbial fuel cell (DC-MFC) using different electron acceptors. The SC-MFC used oxygen from the air as the cathode, while the DC-MFC used diluted hydrogen peroxide. Testing found the DC-MFC produced a higher open circuit voltage of 448mV compared to 200mV for the SC-MFC. The DC-MFC also generated more power, with a maximum power of 7.57mW and coulombic efficiency of 9.2%, versus 0.46mW and 1.88% respectively for the SC-MFC. This suggests hydrogen per
Enhancement of Heat Transfer in Heat Pipes using Silver/Benzene based Nano-Co...IRJET Journal
This document summarizes research into enhancing heat transfer in heat pipes using silver/benzene-based nano-coolants. It first discusses how nanofluids can improve heat transfer efficiency. It then analyzes the thermal conductivity of various base fluids and how adding 1-5% silver nanoparticles by volume increases thermal conductivity of benzene-based nanofluids up to 15% and 24%, respectively, according to theoretical models and experimental correlations. The document suggests nanofluids may increase heat pipe performance for cooling electronics and other engineering applications.
1. The document discusses applications of nanofluids in solar energy systems, specifically their use in improving the efficiency of solar collectors.
2. Adding small amounts of nanoparticles to the working fluid of solar collectors can significantly increase their efficiency until an optimal volume fraction of around 0.5% is reached.
3. Different types of nanofluids - including those with carbon nanotubes, silver, aluminum, and titanium dioxide nanoparticles - have been found to enhance collector efficiency compared to base fluids alone.
Targeted Band Structure Design and Thermoelectric Materials Discovery Using H...Anubhav Jain
This work was supported by funding from the U.S. Department of Energy and involved collaborations with researchers from Northwestern University, Universite Catholique de Louvain, Dalhousie University, and UC Berkeley/LBNL. Using high-throughput computational methods, over 50,000 compounds were screened to discover new thermoelectric materials, identifying YCuTe2 as a promising candidate with a calculated zT of 0.75. Experimental synthesis and testing achieved a maximum zT of 0.75 for this material. Future work will involve developing more accurate electronic transport models, expanding the materials library through substitutional predictions, and applying machine learning to discover new structure-property relationships.
Computational Discovery of Thermal Fluids with Enhanced Heat CapacityAnubhav Jain
(1) The document discusses a project to develop a thermal fluid with enhanced heat capacity through computational discovery of thermally activated covalent bond formation.
(2) The approach involves using computational screening of potential reactions to identify systems where heat is absorbed or released during covalent bond breaking and formation on heating and cooling, respectively.
(3) Preliminary experimental results on computationally predicted systems show heat capacity enhancements within organic solvents and water, demonstrating the potential of the approach.
The Materials Project and computational materials discoveryAnubhav Jain
1. The Materials Project aims to accelerate materials discovery through high-throughput computational screening of materials properties using density functional theory calculations.
2. Over 60,000 compounds have been computed so far, with properties including total energies, optimized structures, band structures, and elastic tensors.
3. The goal is to compute properties for over 90,000 materials to help researchers discover new materials for applications like batteries, thermoelectrics, and other energy technologies.
Application of the Materials Project database and data mining towards the des...Anubhav Jain
This document summarizes research into using high-throughput density functional theory (DFT) calculations and data mining of the Materials Project database to design new thermoelectric and functional materials. Key findings include identifying new thermoelectric materials like TmAgTe2 with a peak zT of 0.75 through screening 40,000 compounds. Preliminary analysis also began to understand how to control band structure by ranking elemental orbitals' likelihood of forming the valence band maximum and conduction band minimum. The overall goal is to accelerate materials discovery and design through computational modeling and data mining at massive scales.
Combining High-Throughput Computing and Statistical Learning to Develop and U...Anubhav Jain
This document summarizes research into developing new thermoelectric materials through high-throughput computing and statistical learning. Key points:
- Thermoelectric materials can convert heat to electricity but require high figure of merit (ZT). Computational screening of over 50,000 compounds has identified promising candidates.
- TmAgTe2 and YCuTe2 were discovered through this method and experimentally validated, with zT of 0.75 for YCuTe2.
- Bournonite materials like CuPbSbS3 have low thermal conductivity but require improved electrical properties. Over 300 substitutions were modeled to explore variations.
- Open data resources like Materials Project and tools like MatMiner being developed to enable data mining and accelerate materials
This document summarizes a study that compared a single chamber microbial fuel cell (SC-MFC) to a double chamber microbial fuel cell (DC-MFC) using different electron acceptors. The SC-MFC used oxygen from the air as the cathode, while the DC-MFC used diluted hydrogen peroxide. Testing found the DC-MFC produced a higher open circuit voltage of 448mV compared to 200mV for the SC-MFC. The DC-MFC also generated more power, with a maximum power of 7.57mW and coulombic efficiency of 9.2%, versus 0.46mW and 1.88% respectively for the SC-MFC. This suggests hydrogen per
Enhancement of Heat Transfer in Heat Pipes using Silver/Benzene based Nano-Co...IRJET Journal
This document summarizes research into enhancing heat transfer in heat pipes using silver/benzene-based nano-coolants. It first discusses how nanofluids can improve heat transfer efficiency. It then analyzes the thermal conductivity of various base fluids and how adding 1-5% silver nanoparticles by volume increases thermal conductivity of benzene-based nanofluids up to 15% and 24%, respectively, according to theoretical models and experimental correlations. The document suggests nanofluids may increase heat pipe performance for cooling electronics and other engineering applications.
1. The document discusses applications of nanofluids in solar energy systems, specifically their use in improving the efficiency of solar collectors.
2. Adding small amounts of nanoparticles to the working fluid of solar collectors can significantly increase their efficiency until an optimal volume fraction of around 0.5% is reached.
3. Different types of nanofluids - including those with carbon nanotubes, silver, aluminum, and titanium dioxide nanoparticles - have been found to enhance collector efficiency compared to base fluids alone.
Waveguide Fixture Based Permittivity Determination of Non-Conducting MaterialsPallavi Malame
This document discusses dielectric properties and measurement techniques. It describes dielectric constant as a measure of how energy from an external electric field is stored in a material, and loss factor as a measure of how dissipative a material is. The transmission line method for dielectric spectroscopy involves measuring reflection and transmission coefficients using a vector network analyzer connected to a sample holder. It can accurately measure dielectric properties of solids and granulated materials in real time and has applications in industries like wood and paper as well as measuring metamaterials, PCB substrates, and powders.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
The document reports on a study of the AC and DC conductivity of three glycine family nonlinear optical (NLO) single crystals: Trisglycine Zinc Chloride (TGZC), Triglycine Acetate (TGAc), and Glycine Lithium Sulphate (GLS). The AC conductivity was measured from 50 Hz to 5 MHz and increased with temperature for all crystals. The activation energies calculated from the AC conductivity were 0.035 eV for TGZC, 0.075 eV for TGAc, and 0.10 eV for GLS. The DC conductivity also increased with temperature from 313 K to 423 K, and the activation energies calculated were 0.050 eV for TGZC, 0.060 eV
Abstract: Nanotechnology is concerned with the materials and systems whose structures and components reveal novel and significantly improved physical, chemical, and biological properties, phenomena, and processes due to their micro size. Workforce development is needed to achieve the benefits of nanotechnology development along with technology transfer. The intensity should be on hands-on educational experiences by developing nano-tech laboratory demonstration experiments that could be adaptable and combined into existing courses in engineering and engineering technology. Theoretical heat transfer rates were calculated using existing relationships in the literature for conventional fluids and nano fluids. Experiments were conducted to determine the actual heat transfer rates under operational conditions using nanofluids and the heat transfer enhancement determined compared to fluids without nanoparticles.
Study of Boron Based Superconductivity and Effect of High Temperature Cuprate...IOSR Journals
This paper illustrates the main normal and Boron superconducting state temperature properties of magnesium diboride, a substance known since early 1950's, but lately graded to be superconductive at a remarkably high critical temperature Tc=40K for a binary synthesis. What makes MgB2 so special? Its high Tc, simple crystal construction, large coherence lengths, high serious current densities and fields, lucidity of surface boundaries to current promises that MgB2 will be a good material for both large scale applications and electronic devices. Throughout the last seven month, MgB2 has been fabricated in various shape, bulk, single crystals, thin films, ribbons and wires. The largest critical current densities >10MA/cm2 and critical fields 40T are achieved for thin films. The anisotropy attribution inferred from upper critical field measurements is still to be resolved, a wide range of values being reported, γ = 1.2 ÷ 9. Also there is no consensus about the existence of a single anisotropic or double energy cavity. One central issue is whether or not MgB2 represents a new class of superconductors, being the tip of an iceberg that waits to be discovered. Until now MgB2 holds the record of the highest Tc among simple binary synthesis. However, the discovery of superconductivity in MgB2 revived the interest in non-oxides and initiated a search for superconductivity in related materials, several synthesis being already announced to become superconductive: TaB2, BeB2.75, C-S composites, and the elemental B under pressure.
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier...AM Publications
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier Discharge (DBD) Plasma has been simulated using the Simulink-Matlab R2010a software. Plasma reactor being used as the basis to determine the parameters in the circuit is in the coaxial form made of pyrex glass with an iron rod as the active electrode and spiral copper wire as passive electrode. The reactor was filled with argon gas with the flow rate of 2 L/s. Simulation circuit model which was prepared based on a DBD equivalent circuit, operated in a voltage range of 1.0 kV to 6.0 kV for frequency of 10 kHz to 66 kHz. Electrical characterization was performed to describe the plasma discharge that occurs in the reactor. The datas of supply voltage and current, as well as voltage and current discharge, was used to determine the average power during one period. From the simulation was obtained an increase in supply and discharge currents with increasing of frequency at the same operating voltage. Discharge power has increased in a specific voltage and increased frequency. It is obtained the average discharge power for 5.5 kV of 11.28 W and 10.90 W at a frequency of 21 kHz and 24 kHz, respectively. The highest efficiency obtained from the simulation that achieved at voltage of 1 kV and frequency of 45.7 kHz is equal to 56.59%.
Thermophysical properties of Single Wall Carbon Nanotubes and its effect on e...Sabiha Akter Monny
This document investigates the thermophysical properties of single wall carbon nanotubes (SWCNTs) suspended in water and examines how this nanofluid affects the exergy efficiency of a flat plate solar collector. The nanofluid was characterized through various tests and was found to have increased specific heat, thermal conductivity, and viscosity compared to water alone. When used as the heat transfer fluid in a flat plate solar collector, the nanofluid increased the maximum energy efficiency up to 95.12% and exergy efficiency up to 26.25% compared to just water, which achieved 42.07% and 8.77% respectively. This study shows for the first time that SWCNTs-water nanofluid can enhance the thermal performance of flat
To study the behavior of nanofluids in heat transfer applications a revieweSAT Journals
Abstract Using nanofluids as an innovative kind of liquid blend including trivial volume fraction (in percent) of millimeter or nanometer size powdered particles with base fluids is fairly a novel arena or idea. The objective of this presented review paper is to inspect the performance of the nanofluid-based solar collector (NBSC). In past few years for a number of experimental and industrial thermal engineering systems solar energy has proven to be the best input energy source. Nanofluids are the fluid that has shown various developments in the thermal properties over the past decade. In the field of nanotechnology, nano fluids have a great potential to enhance the rheological properties like thermal conductivity of base fluid like water, ethanol etc. Nanofluids are the suspension of mainly the base fluid like water in nanoparticles such as alumina (Al2O3) of size micro or milimetre and shows distinctive features than that of conservative fluids used. Because of better rheological properties nanofluids are utilized to build up the performance of conventional solar thermal engineering systems. The presented literature review presents a detailed discussion about the solar collectors, applications of nanofluids in solar collector and their augmentation in thermo physical properties. Keywords: Nano fluids, Nanoparticles, Solar collector, Thermal conductivity
This document discusses applications of nanofluids in solar thermal systems. It begins by defining nanofluids as fluids containing nanometer-sized particles suspended in a base fluid such as water or ethylene glycol. Some examples of nanofluids are then provided. The document then discusses how nanofluids can improve the efficiency of solar collectors and concentrated solar power systems by enhancing heat transfer compared to conventional working fluids like water or oil. Several studies are summarized that examine the effects of varying nanoparticle properties and concentrations on collector efficiency. The document also considers the economic and environmental impacts of using nanofluids in solar thermal applications.
Dielectric properties of pure and ni2+ doped glycine sodium sulfate crystalseSAT Journals
Abstract Pure and Ni2+ added glycine sodium sulfate (GSS) single crystals were grown by the slow evaporation technique and characterized chemically, structurally, thermally, optically, mechanically and electrically. Effect of Ni2+ addition as an impurity on the properties of GSS has also been investigated. All the six crystals grown exhibit normal dielectric behavior and are found to be thermally stable up to 250˚C, NLO active and mechanically soft. The Ni2+ addition is found to increase the dielectric parameters. The low dielectric constant values observed for pure GSS indicate that GSS is not only a promising NLO material but also a low dielectric constant value dielectric material. Keywords: Activation energy, Crystal growth, Dielectric crystal, Electrical properties, X-ray diffraction
The document outlines Cliff Tsai's portfolio in reverse chronological order, summarizing 5 projects he worked on between 2009-2014 related to plasma technology development and applications. The projects involved using atmospheric plasma jets to deposit thin films for applications like rapid bacterial spore killing, polymer coating of temperature-sensitive surfaces, and metal deposition in open air, as well as fundamental plasma physics studies. Key accomplishments included publications in peer-reviewed journals and obtaining patents. The portfolio demonstrates Cliff's experience and skills in areas like plasma engineering, chemistry, medicine, polymer processing and microbiology.
Lattice Energy LLC- New Russian Experiments Further Confirm Widom-Larsen Theo...Lewis Larsen
The document discusses a theory put forth by Widom and Larsen that can explain low-energy nuclear reaction (LENR) phenomena. The theory proposes that collective electromagnetic effects in condensed matter can produce ultra-low momentum neutrons and neutrinos from protons and "heavy" electrons via weak interactions, without needing high temperatures. These neutrons can then catalyze nuclear reactions by being captured by nearby nuclei, since neutrons have no charge and do not face Coulomb barriers. The theory may explain recent experimental results by Barmina et al. that observed tritium production using laser irradiation techniques.
This document presents a thesis analyzing the stability margin of superconducting cables for the High Luminosity Large Hadron Collider (HiLumi-LHC) project at CERN. It uses both zero-dimensional and one-dimensional numerical models to simulate the electro-thermal behavior of Nb3Sn cables during a quench induced by beam losses. The results show the quench energy for the Nb3Sn inner triplet quadrupole magnet is significantly different than for the existing NbTi magnets. Comparisons with NbTi cables highlight differences in quench performance between impregnated Nb3Sn cables and non-impregnated NbTi cables in their typical operating conditions.
This document summarizes a study that investigated the interaction between DNA and gasoline using cyclic voltammetry (CV). DNA and gasoline were mixed in a 1:1 ratio and subjected to CV analysis. Voltammograms showed differences in the electrochemical response of DNA when mixed with gasoline compared to published responses of pure DNA, indicating distortion of DNA upon interaction with gasoline. The authors believe this novel approach could be developed further to analyze DNA damage from petroleum products and propose it provides a methodology to develop DNA-based electrochemical sensors. However, they note the research is preliminary and requires additional experimentation.
The document describes a study that uses design of experiments (DoE) to optimize slurry-cast cathodes for solid-state batteries. Various combinations of polymer binder type and content and conductive carbon additive type and content were tested as cathode composites. Electrochemical and mechanical performance data from the experiments were analyzed using statistical software to identify optimal combinations. The predictions identified polyisobutene as the best binder and vapor-grown carbon fibers as the best additive to maximize specific capacity. Hydrogenated nitrile butadiene rubber and vapor-grown carbon fibers provided the best combination to maximize capacity retention. Additional tests were conducted to understand changes during cycling.
This document discusses experiments on conduction and breakdown mechanisms in transformer oil. For conduction experiments, three stages were identified prior to breakdown for highly nonuniform fields: 1) a resistive current at low fields, 2) a "tunneling" mechanism leading to rapid current rise as field increases, and 3) current reaching space charge saturation at high fields, with an apparent mobility of 3 x 10-3 cm2 V s. Breakdown shows polarity dependence. Negative needle/plane breakdown voltage reduces 50% at hundreds of mtorr pressure, while positive needle reduces only 10%, indicating the breakdown mechanism does not have a strong gaseous component. Shadowgraphy and electrical measurements support a gas bubble model for cathode-initiated breakdown.
1. The document describes a new nanohybrid material composed of polyoxomolybdate, polypyrrole, and graphene oxide for use as a high-power symmetric supercapacitor electrode.
2. The nanohybrid was synthesized via a one-pot reaction where polyoxomolybdate acted as an oxidizing agent to polymerize pyrrole monomers onto graphene oxide nanosheets.
3. Structural and morphological analysis showed the nanohybrid had an excellent architecture with good interfacial contact between components, enabling fast redox reactions for high capacitive performance.
The intern designed a target capsule and holder for irradiating uranium-238 to produce medical and security isotopes. They also compiled and analyzed nuclear reaction cross sections from previous proton irradiation of thorium-232 to improve models for predicting isotope production, supporting applications in medicine and national security. The work contributed to the goals of the Los Alamos National Laboratory in isotope production and nuclear data analysis.
APS D63.00002 Tight Binding Simulation of Finite Temperature Electronic Struc...DavidAbramovitch1
This document presents a new tight-binding model for simulating the electronic structure of methylammonium lead iodide (MAPbI3) at finite temperatures. The model improves upon previous work by better predicting transverse phonon modes and charge fluctuations. It is parameterized using DFT calculations and Wannier90 projections onto atomic orbitals. Tests show the new model more accurately captures bandgap fluctuations with temperature compared to DFT. The model allows for new simulations of nanostructures, surfaces, and other properties of perovskites.
IRJET- Effect of Volume Concentration on Various Thermo-Physical Properties o...IRJET Journal
This document presents a theoretical analysis of the effect of volume concentration on various thermo-physical properties of copper oxide (CuO) nanofluid used in a flat plate solar collector. A mathematical model and MATLAB code were developed to calculate properties like density, specific heat, thermal conductivity, viscosity, and Nusselt number. The results showed that density, viscosity, and thermal conductivity increased with higher nanoparticle volume concentration, while specific heat decreased. The Nusselt number also increased with higher volume concentration and larger nanoparticle diameter. In conclusion, CuO nanofluid can enhance the efficiency of flat plate solar collectors due to improved thermo-physical properties at higher nanoparticle concentrations and diameters.
This document contains the resume of Esther Peter Umoren. It outlines her personal and contact details, skills and qualifications, employment history and education. Her experience includes roles in administration, customer relations, and translation services. She holds a Bachelor's degree in Foreign Languages from the University of Nigeria and is seeking new opportunities.
Waveguide Fixture Based Permittivity Determination of Non-Conducting MaterialsPallavi Malame
This document discusses dielectric properties and measurement techniques. It describes dielectric constant as a measure of how energy from an external electric field is stored in a material, and loss factor as a measure of how dissipative a material is. The transmission line method for dielectric spectroscopy involves measuring reflection and transmission coefficients using a vector network analyzer connected to a sample holder. It can accurately measure dielectric properties of solids and granulated materials in real time and has applications in industries like wood and paper as well as measuring metamaterials, PCB substrates, and powders.
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
journal publishing, how to publish research paper, Call For research paper, international journal, publishing a paper, IJERD, journal of science and technology, how to get a research paper published, publishing a paper, publishing of journal, publishing of research paper, reserach and review articles, IJERD Journal, How to publish your research paper, publish research paper, open access engineering journal, Engineering journal, Mathemetics journal, Physics journal, Chemistry journal, Computer Engineering, Computer Science journal, how to submit your paper, peer reviw journal, indexed journal, reserach and review articles, engineering journal, www.ijerd.com, research journals,
yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
The document reports on a study of the AC and DC conductivity of three glycine family nonlinear optical (NLO) single crystals: Trisglycine Zinc Chloride (TGZC), Triglycine Acetate (TGAc), and Glycine Lithium Sulphate (GLS). The AC conductivity was measured from 50 Hz to 5 MHz and increased with temperature for all crystals. The activation energies calculated from the AC conductivity were 0.035 eV for TGZC, 0.075 eV for TGAc, and 0.10 eV for GLS. The DC conductivity also increased with temperature from 313 K to 423 K, and the activation energies calculated were 0.050 eV for TGZC, 0.060 eV
Abstract: Nanotechnology is concerned with the materials and systems whose structures and components reveal novel and significantly improved physical, chemical, and biological properties, phenomena, and processes due to their micro size. Workforce development is needed to achieve the benefits of nanotechnology development along with technology transfer. The intensity should be on hands-on educational experiences by developing nano-tech laboratory demonstration experiments that could be adaptable and combined into existing courses in engineering and engineering technology. Theoretical heat transfer rates were calculated using existing relationships in the literature for conventional fluids and nano fluids. Experiments were conducted to determine the actual heat transfer rates under operational conditions using nanofluids and the heat transfer enhancement determined compared to fluids without nanoparticles.
Study of Boron Based Superconductivity and Effect of High Temperature Cuprate...IOSR Journals
This paper illustrates the main normal and Boron superconducting state temperature properties of magnesium diboride, a substance known since early 1950's, but lately graded to be superconductive at a remarkably high critical temperature Tc=40K for a binary synthesis. What makes MgB2 so special? Its high Tc, simple crystal construction, large coherence lengths, high serious current densities and fields, lucidity of surface boundaries to current promises that MgB2 will be a good material for both large scale applications and electronic devices. Throughout the last seven month, MgB2 has been fabricated in various shape, bulk, single crystals, thin films, ribbons and wires. The largest critical current densities >10MA/cm2 and critical fields 40T are achieved for thin films. The anisotropy attribution inferred from upper critical field measurements is still to be resolved, a wide range of values being reported, γ = 1.2 ÷ 9. Also there is no consensus about the existence of a single anisotropic or double energy cavity. One central issue is whether or not MgB2 represents a new class of superconductors, being the tip of an iceberg that waits to be discovered. Until now MgB2 holds the record of the highest Tc among simple binary synthesis. However, the discovery of superconductivity in MgB2 revived the interest in non-oxides and initiated a search for superconductivity in related materials, several synthesis being already announced to become superconductive: TaB2, BeB2.75, C-S composites, and the elemental B under pressure.
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier...AM Publications
Analysis of Electric Circuit Model on Atmospheric Pressure Dielectric Barrier Discharge (DBD) Plasma has been simulated using the Simulink-Matlab R2010a software. Plasma reactor being used as the basis to determine the parameters in the circuit is in the coaxial form made of pyrex glass with an iron rod as the active electrode and spiral copper wire as passive electrode. The reactor was filled with argon gas with the flow rate of 2 L/s. Simulation circuit model which was prepared based on a DBD equivalent circuit, operated in a voltage range of 1.0 kV to 6.0 kV for frequency of 10 kHz to 66 kHz. Electrical characterization was performed to describe the plasma discharge that occurs in the reactor. The datas of supply voltage and current, as well as voltage and current discharge, was used to determine the average power during one period. From the simulation was obtained an increase in supply and discharge currents with increasing of frequency at the same operating voltage. Discharge power has increased in a specific voltage and increased frequency. It is obtained the average discharge power for 5.5 kV of 11.28 W and 10.90 W at a frequency of 21 kHz and 24 kHz, respectively. The highest efficiency obtained from the simulation that achieved at voltage of 1 kV and frequency of 45.7 kHz is equal to 56.59%.
Thermophysical properties of Single Wall Carbon Nanotubes and its effect on e...Sabiha Akter Monny
This document investigates the thermophysical properties of single wall carbon nanotubes (SWCNTs) suspended in water and examines how this nanofluid affects the exergy efficiency of a flat plate solar collector. The nanofluid was characterized through various tests and was found to have increased specific heat, thermal conductivity, and viscosity compared to water alone. When used as the heat transfer fluid in a flat plate solar collector, the nanofluid increased the maximum energy efficiency up to 95.12% and exergy efficiency up to 26.25% compared to just water, which achieved 42.07% and 8.77% respectively. This study shows for the first time that SWCNTs-water nanofluid can enhance the thermal performance of flat
To study the behavior of nanofluids in heat transfer applications a revieweSAT Journals
Abstract Using nanofluids as an innovative kind of liquid blend including trivial volume fraction (in percent) of millimeter or nanometer size powdered particles with base fluids is fairly a novel arena or idea. The objective of this presented review paper is to inspect the performance of the nanofluid-based solar collector (NBSC). In past few years for a number of experimental and industrial thermal engineering systems solar energy has proven to be the best input energy source. Nanofluids are the fluid that has shown various developments in the thermal properties over the past decade. In the field of nanotechnology, nano fluids have a great potential to enhance the rheological properties like thermal conductivity of base fluid like water, ethanol etc. Nanofluids are the suspension of mainly the base fluid like water in nanoparticles such as alumina (Al2O3) of size micro or milimetre and shows distinctive features than that of conservative fluids used. Because of better rheological properties nanofluids are utilized to build up the performance of conventional solar thermal engineering systems. The presented literature review presents a detailed discussion about the solar collectors, applications of nanofluids in solar collector and their augmentation in thermo physical properties. Keywords: Nano fluids, Nanoparticles, Solar collector, Thermal conductivity
This document discusses applications of nanofluids in solar thermal systems. It begins by defining nanofluids as fluids containing nanometer-sized particles suspended in a base fluid such as water or ethylene glycol. Some examples of nanofluids are then provided. The document then discusses how nanofluids can improve the efficiency of solar collectors and concentrated solar power systems by enhancing heat transfer compared to conventional working fluids like water or oil. Several studies are summarized that examine the effects of varying nanoparticle properties and concentrations on collector efficiency. The document also considers the economic and environmental impacts of using nanofluids in solar thermal applications.
Dielectric properties of pure and ni2+ doped glycine sodium sulfate crystalseSAT Journals
Abstract Pure and Ni2+ added glycine sodium sulfate (GSS) single crystals were grown by the slow evaporation technique and characterized chemically, structurally, thermally, optically, mechanically and electrically. Effect of Ni2+ addition as an impurity on the properties of GSS has also been investigated. All the six crystals grown exhibit normal dielectric behavior and are found to be thermally stable up to 250˚C, NLO active and mechanically soft. The Ni2+ addition is found to increase the dielectric parameters. The low dielectric constant values observed for pure GSS indicate that GSS is not only a promising NLO material but also a low dielectric constant value dielectric material. Keywords: Activation energy, Crystal growth, Dielectric crystal, Electrical properties, X-ray diffraction
The document outlines Cliff Tsai's portfolio in reverse chronological order, summarizing 5 projects he worked on between 2009-2014 related to plasma technology development and applications. The projects involved using atmospheric plasma jets to deposit thin films for applications like rapid bacterial spore killing, polymer coating of temperature-sensitive surfaces, and metal deposition in open air, as well as fundamental plasma physics studies. Key accomplishments included publications in peer-reviewed journals and obtaining patents. The portfolio demonstrates Cliff's experience and skills in areas like plasma engineering, chemistry, medicine, polymer processing and microbiology.
Lattice Energy LLC- New Russian Experiments Further Confirm Widom-Larsen Theo...Lewis Larsen
The document discusses a theory put forth by Widom and Larsen that can explain low-energy nuclear reaction (LENR) phenomena. The theory proposes that collective electromagnetic effects in condensed matter can produce ultra-low momentum neutrons and neutrinos from protons and "heavy" electrons via weak interactions, without needing high temperatures. These neutrons can then catalyze nuclear reactions by being captured by nearby nuclei, since neutrons have no charge and do not face Coulomb barriers. The theory may explain recent experimental results by Barmina et al. that observed tritium production using laser irradiation techniques.
This document presents a thesis analyzing the stability margin of superconducting cables for the High Luminosity Large Hadron Collider (HiLumi-LHC) project at CERN. It uses both zero-dimensional and one-dimensional numerical models to simulate the electro-thermal behavior of Nb3Sn cables during a quench induced by beam losses. The results show the quench energy for the Nb3Sn inner triplet quadrupole magnet is significantly different than for the existing NbTi magnets. Comparisons with NbTi cables highlight differences in quench performance between impregnated Nb3Sn cables and non-impregnated NbTi cables in their typical operating conditions.
This document summarizes a study that investigated the interaction between DNA and gasoline using cyclic voltammetry (CV). DNA and gasoline were mixed in a 1:1 ratio and subjected to CV analysis. Voltammograms showed differences in the electrochemical response of DNA when mixed with gasoline compared to published responses of pure DNA, indicating distortion of DNA upon interaction with gasoline. The authors believe this novel approach could be developed further to analyze DNA damage from petroleum products and propose it provides a methodology to develop DNA-based electrochemical sensors. However, they note the research is preliminary and requires additional experimentation.
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Queremos ser enfáticos en que estos trabajos tienen Propiedad Intelectual por lo que queda totalmente prohibida su reproducción parcial o total, así como ser utilizados por otro autor, a excepción de que los compartan como citas de autor o referencias bibliográficas. Toda esta información también quedará a su disposición desde nuestro sitio web www.umagister.com,
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FINAL PAPER Rev1
1. NRE 4232 Nuclear and Radiological Engineering p. 1/29 Spring 2015
Activation Concern for I2
S-LWR In-Vessel Primary Heat Exchangers
William Bryans, Adnan Hashim, Joshua McCann,
Ayuko Morikawa, Syfuddin Rashid
Nuclear and Radiological Engineering
Georgia Institute of Technology
770 State St, Boggs Bldg.
Atlanta, GA 30332-0745
The I2S-LWR reactor incorporates integrated heat exchangers and other secondary components built
within the pressure vessel to minimize total volume and increase the ease of transportability. However, due to
this integrated heat exchanger design, the possibility of heat exchanger material activation may be a concern.
Thus the objective of this investigation is to alter heat exchanger height to evaluate a possible method of
reducing total heat exchanger activation, which in modern industry could relate to reducing worker radiation
exposure and future unforeseeable costs.Using MCNP,the study analyzes typical neutron flux values generated
fromthe reactor core that strike the heat exchanger surfaces. Once an exact value is calculated, it beco mes
possible to utilize this model as a foundation to evaluate other variables within the pressure vessel.
Key Words: Heat Exchanger, Neutron Activation, MCNP Model, I2
S-LWR
1. INTRODUCTION
1.1 Literature Review
1.1.1. Material Research
Numerous articles were researched and studied to learn more information on the design topic. The
articles found gave a better understanding on materials, shielding, MCNP coding, and fouling/plating. The
article that was most helpful for material selections was “Experimental neutron attenuation measurements in
possible fast reactor shield materials” by Mawutorli Nyarku, Ramanthapura S. Keshavamurthy, Venkata D.
Subrmanian, Adish Haridas, and Eric T. Glover. This article was very helpful because it discussed the best
shielding materials for neutron attenuation. The authors researched whether Ferro-tungsten or mild steels would
be better at attenuating epithermal and fast neutrons. Results showed that even though mild steels work
exceptionally well at attenuating neutrons, Ferro-tungsten was found to be a more effective neutron attenuator.
Another article that was beneficial with shielding and materials was “Shielding experiments for
optimization of shield materials in fast reactor using SSNTDs” by R V Kolekar, R Kumar, and DN Sharma. By
using activation techniques and solid state nuclear track detectors the authors researched neutron transport
through several shield materials. Stainless steel-316, borated graphite, and sodium were the three single shield
materials used during the experiment. Results showed stainless steel-316 caused more backscattering than both
the borated graphite and sodium.
2. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 2/29 Spring 2015
1.1.2. Fouling and Plating Concerns
After brief discussion with Dr. Petrovic, the possibility of having the possibility of fouling and plating
within the heat exchangers became a concern in the overall analysis. Fouling typically is formed from residual
micro-particle deposition within the heat exchangers whereas plating occurs when chemicals are inserted into
the system to remove said microparticles. These chemicals eventually lead to carbonate based buildup, examples
being compounds such as calcium carbonate and boron carbonate (Cite “alaquainc” link). After a short period of
investigation into this variable of concern and acquiring a better understanding, the issue was presented to the
experts at the Waterford 3 plant. Though the conversation that took place over the topic was relatively brief, the
answer provided by Waterford 3 was considered a reliable source. A more detailed description entailing the
conversation follows below.
1.1.3. Discussion with Waterford 3 Nuclear Power Plant, Kenner, Louisiana
In order to acquire a better understanding of the general structure, function, operation, and composition
of the primary coolant systems that directly worked in tandem with the reactor, the Waterford 3 nuclear plant
was contacted. With the assistance of Pamela Hernandez, Waterford 3’s Senior Nuclear Engineer Manager, and
Keith Kunkel, Waterford 3’s Heat Systems Manager, significant documentation involving operation and
construction of the reactor systems as well as general explanations were acquired. Direct copies of the emails as
well as the documents provided by Waterford 3 are available for inspection in the appendices.
The documents displayed values including typical heat exchanger, pressure vessel, and biological shield
dimensions and specifications. The documents also gave general systems operation and flow systems found
within the primary coolant loop. Both Keith as well as Pamela directly answered concerns involving buildup and
fouling. As quoted by Mr. Kunkel, “We get a buildup of corrosion products on the secondary side of the steam
generator. The primary side is all stainless steel and remains clean.” These statements alongside the documents
provided remain to be the most significant contributions given by Waterford 3 Staff.
1.1.4. Fiscal Correlation to Possible Radiation Worker Dose
The overall scope of the investigation is to ascertain the total activation in the primary heat exchangers
from the core via neutron flux. The application of this investigation in the end is to utilize this activation value
as an accurate foundation to acquire possible future dose deposition to radiation workers that may interact with
the heat exchangers throughout the timespan of its operation. This activation value may also be used as a
fundamental value for other investigative analysis’ involving heat exchanger impacts outside the field of dose
study. However, in order to accurately relate the heat exchangers’ activation, possible deposition, and its
possible risk magnitude to workers, a brief analysis must be performed on the direct correlation between the U.S
dollar and the unit of dose utilized by plants for cumulative dose deposition: the person-rem. The person-rem
unit accounts for the total dose in rem acquired by all workers working within a similar range of operations in a
set period of time and area of operation. Finding this correlation deemed to be a relatively difficult task as the
underlying philosophy of correlating life to a monetary material value is one of much debate and discord.
However, documents provided by Dr. Bojan Petrovic, an advisor provided the short and to the point answers
that were sought. A specific document titled “Reassessment of NRC’s Dollar Per Person-Rem Conversion
Factor Policy” created by the Division of Regulatory Applications, US Regulatory Commission provided the
official value allotted to financing the compensation rate for injury or suffering accrued by personnel exposed to
radiation doses. The value set in 1995 was 2000 U.S dollars. Forward inflated this value can be related to
3. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 3/29 Spring 2015
approximately 3080 U.S dollars present day of this paper (April 18th
, 2015) (Division of Regulatory
Applications, 1995).
1.1.5. Similar MCNP Project
One of the articles that influenced some of the design decisions of this project was the “PWR Facility
Dose Modeling Using MCNP5 and the CADIS/ADVANTG Variance-Reduction Methodology” performed at
Oak Ridge National Laboratory by E. Blakeman et al. In this study, the dose from a PWR core was measured
across the plant facilities at different reactor conditions. Several ideas were taken from this model such as using
a watt fission spectrum for the source neutrons, homogenizing the core, using a mesh tally, and variance
reduction techniques.
1.1.6. CADto MCNP via STEP File
Given the intricate nature of the I2S-LWR design, considerable thought was given in finding an efficient
yet effective model to accurately represent the neutron activation experienced by the PHXRs. Given the
primary language to code these types of activations and reactions was through MCNP, it became vital to begin
coding a proper INP file to represent the reactor. Unfortunately, the MCNP language created by Los Alamos
National Laboratory in 1957 has become fairly antiquated, even given the major improvements made upon it.
This has led to the INP files being fairly complicated to understand and often error prone as well. Given the
small base of MCNP users, finding outside resources for help would also prove to be difficult. Thus a natural
cross road was reached,does one learn MCNP code and create the INP file through trial and error, does one find
an intermediary form of coding/design and then convert to MCNP, or does one disregard MCNP entirely.
The third option was quickly disregarded for the reasons mentioned above in that MCNP was the
foremost language in describing neutron particle interactions. The second option was given considerable
thought based off research done in converting CAD files to MCNP files through intermediary STEP files (Zhou
2014). The reason for the intermediary comes from the research community’s desire to utilize a CAD model
data exchange that was leveraged upon neutral files. With that consensus reached, Zhou and his team began
developing complex algorithms to convert these intermediary files into well-written and clean MCNP code. It is
important to remember, while much information can be gleaned from the CAD models, the data specifications in
block 3 of standard MCNP cannot. Zhou’s team ultimately ended their research with improved algorithms in
two dimensions from their previous research, but still look to improve their models in the future.
Given the promise that these types of algorithms were showing, more research was done into software
and code that could convert more manageable programming languages into MCNP INP files. It was quickly
discovered that these models outstripped the budget by magnitudes of over 3 and 4. Given that time was also a
limited resource, the option to find conversion codes was quickly canned, and writing the code by hand was
settled upon.
1.1.7. MCNP Lattice Structure
The majority of the component research was done using the resources given by Dr. Petrovic. This
consisted of a series of reports regarding the I2
S-LWR reactor written for the Interinstitutional Committee for
Academic Program Planning (ICAPP). In particular, a report titled “Integral Inherently Safe Light Water
Reactor (I2
S-LWR) Concept: Integral Vessel Layout” written by Matthew J Memmott of Westinghouse Electric
Company, Matthew Marchese, and Bojan Petrovic was heavily used to gain knowledge of other components
outside of the primary heat exchanger that would be included in the MCNP model. This report outlines the
4. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 4/29 Spring 2015
configuration of the primary system and describes the design and function of all relevant components within it.
Additionally, it mentions alternative configurations for the I2
S-LWR primary system. The physical dimensions
for components such as the primary heat exchanger, pressure vessel, core barrel, and alignment plates used in
the MCNP model was found in this report and played a crucial role in creating a model that was scaled
accurately with the actual reactor design. Some component dimensions,such as upper barrel diameter, were
subject to change as the reactor design was updated. These dimensions were modified per discussion with Dr.
Petrovic.
2. THEORY
2.1. Material Activation Concern in PHXR
The core of the investigation revolves around ascertaining what materials within the heat exchangers are
activated. Once neutron flux is deduced, neutrons traveling with a spectrum of energies strike the heat
exchanger surface with the possibility of activating the material struck. Depending on the material, the type of
radiation emitted can vary, with some reactions being more likely than others. This also means that the
irradiated material decays and forms different isotopes, which in turn, could also decay and release radiation. An
isotope of concern in this case is Iron-58. Iron, when irradiated by neutrons, will form Cobalt-59, which
eventually, will also absorb another neutron and form Cobalt-60m, a metastable isotope that quickly decays to
Cobalt-60. Cobalt-60 is also radioactive, but has a longer half-life than Cobalt-60m. However,Cobalt-60 emits a
form of radiation that is of concern for workers that may interact with the material irradiated. Thus it was
imperative to closely study the decay chains that this iron isotope can create. Other isotopes as of now do not
seem to be a significant source of hazardous radiation due to extremely short half-lives. Below is a diagram
depicting the decay chain of Cobalt-60m to its base form of Nickel (Cite: Wiki decay page and image author for
this and image).
Table I. Decay Products of Concern
Fe-58 Co-59 Co-60m Co-60
Gamma or Beta E (MeV) - - .05859 Beta .31, 1.48 Betas
Half-life - - 10.467 mins 5.272 years
Probability 𝜎 = 1.3 barns 𝜎 = 21.2 barns 100% 98.88%, .12%
Decay or Neutron absorbed N N Decay Decay
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NRE 4232 Nuclear and Radiological Engineering p. 1/29 Spring 2015
Figure 1. Decay Chain Diagram of Daughter Isotopes of Neutron Activation of Iron-58
2.2. Flux Calculation
The current MCNP code utilizes a simplified fuel core that has been homogenized by weight percent of
materials found within it. However, due to the decision to not utilize a fission k-code to emulate an actual core,
it was a necessity to ascertain the average fluence exiting the core. Using values provided from previous I2S-
LWR groups, and some basic reactor physics, the average flux value was found. First, the total thermal output of
3000 MWth was converted to joules per second, which in turn was converted to MeV per second. It is also
known that typical Uranium-235 fission reactions produce approximately 200 MeV/fission. Each fission is
induced by a neutron thus a value of fissions per second is found by dividing the MeV/s power by the
MeV/fissions. However, each fission neutron creates on average 2.76 neutrons per reaction. Thus by multiplying
the fissions per second value by the 2.76 neutrons per fission, the final average neutron fluence can be calculated
(Cite:Team G2, 2014 Burnable Absorbers). Below is the step-by-step calculation.
1 𝑊 = 1
𝐽
𝑠
(1)
1.609𝑥10−13 𝐽
𝑀𝑒𝑉
𝑎𝑛𝑑 200
𝑀𝑒𝑉
𝑓𝑖𝑠𝑠𝑖𝑜𝑛
(2)
Thus:
3000𝑥106 𝐽
𝑠
1.609𝑥10−13 𝐽
𝑀𝑒𝑉
∙
1
200
𝑀𝑒𝑉
𝐹𝑖𝑠𝑠𝑖𝑜𝑛
∙ 2.77
𝑛𝑒𝑢𝑡𝑟𝑜𝑛𝑠
𝑓𝑖𝑠𝑠𝑖𝑜𝑛
(3)
= 2.57303𝑥1020 𝑛𝑒𝑢𝑡𝑟𝑜𝑛𝑠
𝑠
(In simulated core) (4)
2.3. Heat Exchanger Design
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NRE 4232 Nuclear and Radiological Engineering p. 2/29 Spring 2015
The primary heat exchangers that are used in the I2
S-LWR reactor design are manufactured by Heatric
and are called printed circuit heat exchangers (PCHEs). These heat exchangers are mainly composed of
Stainless Steel 304, and utilize a series of stacked cross flow plates that have coolant flowing across them in tiny
channels. The primary and secondary coolants flow in alternating plates throughout the length of the heat
exchanger. Each plate is 2 mm thick with a 350 mm x 600 mm base, and has 150 small channels etched parallel
to the width of the plate. The channels are 1 mm wide by 1 mm deep and have a pitch of 20 mm. In the plates
containing the primary coolant, the fluid enters the plate on its longer side and travels across the 350 mm width
of the plate. On the plates containing the secondary coolant, the fluid enters on the short side of the plate through
a 100 mm cut in the fins, then flows parallel to the width of the plate as well. The plates are stacked vertically on
top of each other to form blocks that are 600 mm in height. Ten of these blocks are then stacked vertically to
form the full heat exchanger, which is 600 cm in length and has a 100 cm by 50 cm base. There are a total of 8
primary heat exchangers that are positioned in a circular pattern above the reactor core (Memmott, Marchese,
Petrovic 2014).
The primary coolant enters the heat exchanger assembly through a rectangular channel cut into the
upper core alignment plate. This channel feeds into a vertical duct that is 980 mm by 186 mm at its highest point
and becomes smaller towards the bottom of the duct. The secondary coolant enters the heat exchangers through
a single 150 mm diameter pipe that feeds into two primary heat exchangers. This flow then exits into a 190 mm
pipe before it recombines into a 150 mm diameter pipe under the heat exchanger (Memmott, Marchese, Petrovic
2014).
Figure 2. Outer View of Printed Circuit Heat Exchanger
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3. MATERIAL CONSTRAINTS
3.1. Material ofHeat Exchanger/Reflector
The first and perhaps the most important aspect in designing any component inside a nuclear reactor is
the type of material used. Various material properties must be considered before choosing a material to be
implemented inside a reactor. The material must be corrosion resistant and absolutely cannot be prone to
activation. Through extensive literature research on materials used in nuclear reactors a list of approximately
ten materials was created for possible materials to use for the PCHE and the reflector. Then further research on
the lists material properties was conducted until the list was narrowed to three materials. The table below shows
the three materials along with important material properties.
Table II. Material Properties
SS-304 Boron Carbide Ferro-Tungsten
Cost ($/kg) 2.84 15 34.83
Melting T (C) 1425 2489.85 1650-2100
Tensile Strength (MPa) 505 261-569 690-3000
Density (kg/m3) 8000 2300 19300
Corrosion Resistance Yes Yes Yes
Boron carbide and Ferro-tungsten both have better melting temperatures and tensile strength than
stainless steel-304. However, the costs of boron carbide and Ferro-tungsten are significantly higher in
comparison to stainless steel-304. Additionally, Ferro-tungsten and boron carbide are both currently not
approved by the NRC, whereas stainless steel-304 is approved by the NRC.
Due to stainless steel-304 being the only material of the three approved by the NRC, it was concluded
the PCHE and the reflector would be made out of stainless steel-304. It is corrosion resistant, has a high melting
temperature and tensile strength, and is relatively low in price.
3.2. Incorporation of a Standalone Shielding Structure
During the preliminary analysis stage of the project, the option of including a standalone shield structure
between the PHXR’s and the core was considered. Theoretically this would have been the most effective
method of reducing activation to the PHXR by reducing neutron flux directly. A plethora of design options were
considered, ranging from a diagonally slanted “wall” between the PHXR and the core to reflect neutrons, to
“plating” the PHXR in carbonate based compound to absorb neutrons. Materials considered included Ferro
Tungsten, SS-304, Boron Carbide, and a Silicon Dioxide based experimental compound. The experimental
8. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 4/29 Spring 2015
compound was intended to act like a neutron absorber by being plated on the surface of the PHXR’s. Ferro-
Tungsten and Boron Carbide would have been plated on top of a steel wall to serve as the standalone shield.
Below is a table of the materials aforementioned and some others not mentioned alongside a few characteristics
analyzed to select the most effective shield:
Table III. Properties of Possible Materials for Standalone Shield
SS-304 Boron Carbide Ferro-Tungsten Mn SiO2 Cu
Melting Temp (K) 1425 2489.25 2100 1246 1600 1085
Cost ($/kg) 2.84 15.00 2.15 34.83 1950.0 5.77
Tensile Strength (MPa @ 300C) 505 269-569 690-3000 7.21 - 220
Corrosion (Y/N) Yes Yes Yes Yes NA No
Density (kg/ 8000 2300 19300 8650 2650 8960
However, after acquiring a better understanding of the internals of the reactor vessel and its plethora of
components, it was concluded that the best option in reality was to not include a standalone shield or plating of
any sort. Due to the costs of acquiring and constructing the aforementioned materials into a usable format, a lack
of true free volume within the pressure vessel to place the shield, and the multitude of unknown safety issues
that are nearly uncorrectable, it was concluded to forego the standalone shield option in the final design for the
project.
4. COST ANALYSIS
4.1. Material Costs
The cost analysis of increasing the height of the reflector and axial location of the primary heat
exchanger units began with the cost of possible materials. The list of researched materials was narrowed down
to three following examination of material properties and cost of material. The three materials were Boron
Carbide, Ferro-Tungsten, and Stainless Steel 304. Table 2 below shows materials and their associated cost per
kilogram. Ferro-Tungsten is 15 dollars per kilogram, Boron Carbide is 34.83 dollars per kilogram, and Stainless
Steel 304 is 2.84 dollars per kilogram. The price of the material is subject to changing over time due market
prices and availability. Numerically the price for Stainless Steel 304 appears to be significantly lower than
Boron Carbide and Ferro-Tungsten. However, relative to the overall cost of manufacturing the reflector and
primary heat exchangers, the material is essentially negligible.
Table IV: Cost of Materials
Material Cost per Kilogram
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NRE 4232 Nuclear and Radiological Engineering p. 5/29 Spring 2015
Boron Carbide 34.83
Ferro-Tungsten 15
Stainless Steel 304 2.84
4.2. Cost ofReflector
The reflector was decided to be composed of 100% Stainless Steel 304. Previously knowing the I2
S-
LWR’s reflector height being 4.058 meters and the thickness being .165 meters the volume of the reflector was
calculated to be 6,384,171.65 cm3
. Having the volume and knowing the density of Stainless Steel 304 being 7.94
g/cm3
, the weight the reflector was calculated to be 50.69 tons. The price of Stainless Steel 304 per ton is 2,978.
Therefore the total cost of I2
S-LWR’s reflector is 150, 954.82 dollars. Every additional cm added on the height
of the reflector would cost approximately 372 dollars.
5. MODELING
5.1. Introduction
The primary expenditure of time in this senior design experiment came from creating an accurate model
in MCNP. To accomplish this, the method of approach decided upon was an incremental addition method. The
initial thought had been to create the fully-fledged model immediately and leave as much time for testing as
possible. However, given the complexity of MCNP and how error prone the code can become, the incremental
method was selected as it allowed for testing throughout the entire process.
In the following analysis an initial model was created and will be explained in detail. From there,
components such as the reflector, pressure vessel, core barrel, etc. are added and explained in detailed with
special attention given to composition, assumptions made to create simplifications in the code, and justification
for dimensions utilized. A brief disclaimer: the numbers used are the most accurate to date, however, as this is a
working model, dimensions can and will change. During our examination period, a few dimensions were
changed in the reactor and these had to be accounted for in the final design.
5.2. Initial Model
The model initially created only contained three components, which included the core itself, the coolant
around the core, and a single heat exchanger. The initial core was modeled as a cylindrical volumetric source
that had an isotropic distribution of neutrons. The material card used in the core was simply a mixture of
Uranium Oxide. The core was placed with its base at the origin of the MCNP model extending upwards with an
active fuel length of 3.66 meters and a radius of 1.485 meters. The core consisted of an inner fuel region, a
stainless steel reflector, and a stainless steel lower barrel with outer radii of 1.485, 1.60, and 1.65 m respectively.
The coolant was supposed to be modeled as light water, however upon later model revision it was discovered
that heavy water had been used instead. This mistake will be brought up again later when looking at the initial
results. Finally, the heat exchanger was modeled as a rectangular prism with a height of 6 meters, a thickness of
1 meter, and a width of 54 cm approximately. The material card used for the heat exchanger was simply the
elemental mixture of stainless steel 304.
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The heat exchanger was placed approximately 3 meters above the core offset from the center. Both the
heat exchanger and core were placed inside of a sphere of water, which in turn was placed inside a graveyard
vacuum sphere to notify MCNP to no longer track particles. A diagram of the initial model can be seen below:
Figure 3. Initial Model in MCNP
The models derived from this model can be seen below when the MCNP code was run for 500,000
particles. As can be seen from this fairly simplistic model, an exponential decay in flux can be seen as the heat
exchanger moves up the pressure vessel.
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NRE 4232 Nuclear and Radiological Engineering p. 7/29 Spring 2015
Figure 4. Flux in Heat Exchanger
5.3. Addition of Components
As mentioned earlier, the initial model also consisted of heavy water instead of light water, which is a
much better moderator of neutrons, which in turn reduced the flux seen by the heat exchanger. From this point,
the next additions made to the model were the additions of the upper barrel, vessel, biological shield, control rod
plates, and the remaining printed circuit heat exchangers. The fuel and reflector were then modified from
cylindrical shapes to a more accurate shape based on fuel assembly location. Finally code was added to account
for changing boron concentration in the water.
The lower barrel was modeled as a cylinder composed of Stainless Steel 304. A thickness of 5 cm was
used, making the outer radius of the lower barrel 1.65 m. A length of 4.358 m was used as the lower barrel
length. For the upper barrel, a decreased outer radius of 1.5 m was used. The upper barrel was also 5 cm thick.
A 25 cm thick stainless steel ring, positioned on top of the lower barrel, was used to connect the upper and lower
barrels. The ring was hollow with the same inner diameter of the upper barrel and outer diameter of the lower
barrel. The upper barrel had a length of 10.43 m, with the total length of the combined barrels being 15.04 m.
The pressure vessel was modeled as a cylinder capped by two half spheres and composed of carbon
steel. The vessel had an inner diameter of 2.45 m and a wall thickness of 27.5 cm. The two vessel domes had a
thickness of 13.75 cm. The cylindrical wall of the vessel was modeled to have a length of 15.04 m. In the actual
design the vessel is approximately 10 % longer. The assumption was made that the shorter dimension would not
affect the flux in the heat exchanger caused by backscattering effects. This assumption is believed to be valid
because the flux was found to be zero far below this position from the core. The difference in vessel length was
for modeling purposes only and was not intended to be a design suggestion. The area outside of the pressure
vessel and between the bioshield was modeled as room temperature air.
The bioshield was modeled as a cylindrical wall with a connecting lower half sphere. The vessel was
composed of concrete and had an inner diameter of 3.03 m and a wall thickness of 30.5 cm. The bioshield was
not modeled to be dimensionally accurate but to simulate any backscattering of neutrons. A thickness was
chosen that would effectively account for the scattered neutrons. Similarly the shield length was chosen to be
equal to that of the vessel in order to conservatively account for the most neutron scatters.
The primary heat exchangers were modeled as rectangular boxes composed of a homogenous mixture of
stainless steel 304 and water. The heat exchangers were modeled to be 100 cm wide with a depth of 54 cm. This
model does not include the primary coolant header. The base of the heat exchanger was positioned at a vertical
location of 6.65 meters away from the base of the core. It was modeled to have a length of 6 meters; however, in
the most recent design the heat exchanger is 6.6 meters in length. This difference is assumed to have negligible
12. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 8/29 Spring 2015
effects because the flux above several meters of the heat exchanger was observed to be zero. The model was
designed to allow the vertical position of the heat exchanger to be adjusted relatively easily. The weight percent
of water was determined by taking into consideration the volume of the micro channels in the heat exchanger. It
was determined that the heat exchanger was 7.3% water and 92.7% steel by weight. The model includes the
eight primary heat exchangers. The secondary decay heat exchangers were not included in this model.
The control rod drive mechanism and alignment plates were modeled as 10 cm thick cylindrical disks
composed of stainless steel. The upper alignment plate was modeled to be located directly on top of the fuel.
The lower and upper CRDMs were positioned at a height 8.43 and 12.9 m in the vertical direction. The radius of
these plates matched the inner radius of the barrel.
Figure 5. 2D Vised Representation of Final MCNP Model (NOT to Scale)
The next step in improving the model was to redefine the fuel region from a cylindrical shape to a more
accurate lattice structure. The fuel core was modeled as a homogenous region with the shape of the combined
121 assemblies. The dimensions for this region were determined from the assembly pitch of 23 cm and number
of assemblies per row in the lattice structure. The weight percentage of the elements that compose the fuel
pellets, cladding, and the coolant were included in this fuel region. The length of the fuel was taken to be the
active length of 3.658 meters.
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Figure 6. Final Model for Reactor Core
(Homogenized fuel shown as purple, reflector and lower barrel shown as light blue)
The change of the fuel shape also affected the reflector dimensions. The reflector was modeled as 100%
Stainless Steel 304. The reflectors outer radius and length remained the same as the initial model with values of
1.6 and 4.058 m respectively. However the inside of the reflector was now defined by the shape of the lattice
structure fuel instead of the cylindrical shape.
5.4. Light Water and Borated Water
One of the most integral parts of the MCNP model is the water incorporated around the different reactor
components. It serves as the primary moderator in the system and reduces the flux seen by the heat exchanger
by orders of magnitude. When the model was initially created, the only line representing water was a single
material card with the atomic percentages of hydrogen and oxygen. However, as the model has advanced, so
has the material card for water.
The first advancement made upon the material card was to incorporate the correct cross sectional data.
By taking a conservative estimate of the water to be 600K at any time, the cross sections of .71c and .53c were
used for were used for Hydrogen and Oxygen respectively.
One important addition made was that of a scattering kernel, or in more formal terms an MT card. The
importance of this card comes into play when considering hydrogen molecularly bound in either water or some
other constituent particle. This binding affects the slower neutrons making collisions, and in turn dictates how
they scatter. Therefore,this MT card takes into account special cross-section data treatments for binding effects
of Hydrogen. It’s important to remember, without the presence of the MT card, Hydrogen would simply be
treated as a monatomic gas, with complete disregard to any binding effects.
The final advancement made upon the material card for water is the sensitivity analysis of heat
exchanger flux with varying concentrations of boric acid. In most typical light water reactors the concentration
of boron decreases with the life of the reactor. In making the model as accurate as possible, the presence of
boron would be added through homogenizing the water with boric acid. The range decided upon would be from
0 ppm to 1000 ppm, broken into 200 ppm segments as specified by Dr. Petrovic. These varying material cards
for different ppm have been included in the code with comment cards as can be seen below:
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NRE 4232 Nuclear and Radiological Engineering p. 10/29 Spring 2015
Figure 7. Material Card for Water in MCNP
By simply removing a comment card indicator ‘c’,and by commenting out the previous moderator, one can go
through and augment the ppm of boron at will.
5.5. Air
The importance of modeling air in the system is realized when adding the biological shield. In the
model air occupies any space outside of the pressure vessel and not inside the biological shield. It fills the
cylinder that designates the graveyard entirely and is composed of a standard composition for air.
This standard composition consists of approximately 75% nitrogen, 23% oxygen and the rest a medley
of carbon and argon. These elements all utilize room temperature cross sections which is designated by not
adding a cross sectional table at the end of the ZAID number. While it is understood that the temperature of air
around the pressure vessel will be more than likely higher than room temperature, the bins MCNP typically
creates for their cross sectional tables are separated by 300 degrees. The importance of including air may not be
paramount, however, it does contribute to certain neutron interactions and thus cannot be substituted with a
vacuum.
5.6. Source Definition
The source definition modeling will be broken into three components to best explain not only the
chronological process taken but allow for readers to easily comprehend the difficulty in defining a correct source
definition.
5.6.1. Homogenization
The very first step in defining the source was to find a way to represent the material in the core. This
could be done through two different methodologies. The first being separating the core into its component parts,
such as the Uranium Silicide (U3Si2) fuel, the water, the cladding, etc. In turn, this would mean a different
material card for each component in the reactor core. However, modeling the intricacies of the complex lattice
structure seen inside the I2
S-LWR and the figure below is not only time consuming in writing the code, but also
time consuming in running the code. By attempting to model the lattice structure exactly, the amount of cells
and surface cards would also exponentially increase.
15. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 11/29 Spring 2015
Figure 8. Core Lattice Structure
The question then becomes,what accuracy of results are needed that would warrant the use of such a
complex code. After consultation with Dr. Petrovic, the idea of completing such a complex structure was
dismissed for the reasons of limited time and code complexity.
The second option is then to homogenize the material inside the core and treat the source as a single
material. The homogenization process is explained through the following table:
Table V. Material Homogenization
First, the weight percentages are found for each individual component of the reactor core. In the model
the core consists of water, cladding made from Oxide Dispersion Strengthened (ODS) steel, and U3Si2. Boron
rods are neglected in this calculation as the highest estimate for flux is desired in the heat exchanger. As boron
16. X1. Heat Exchanger Activation
NRE 4232 Nuclear and Radiological Engineering p. 12/29 Spring 2015
rods act as neutron poison/absorbers they would reduce the overall flux in the core, and ultimately the flux
affecting the heat exchangers.
Returning to homogenization, the weight percentages are taken, and multiplied by the density of the
individual component the weight percentages were pulled from. In this case the density of U3Si2 is 11.3 g/cm3
.
This density is multiplied by the individual elements that make up the U3Si2 which are approximately 7% U-
235, 85% U-238, and 7% Silicon. These values are then multiplied by the volume of the individual component,
which yields the mass of the individual elements in a component. For example in the U3Si2 core fuel here is
approximately 143.0277 g of U-235. Finally this number is divided by the total mass of the core to yield the
homogenized weight percentage. This process is repeated for each component of the core with the final sum of
the weight percentages equaling one.
With these values and the ZAID codes, a material card is created for the homogenized material and can
be seen below:
Figure 9. Material Card for Homogenized Fuel
Note the cross section tables used in the core vary from any other tables used to date. As peak
temperatures in the core are much higher than values found in the water surround the core, the .72c tables are
utilized which correspond to 900K. From this point the question becomes how should the source definition be
modeled, as KCODE or as a Fixed Source?
5.6.2. KCODE
Initially, the design of the source code was modeled as a fixed source. The issue that continually arose
with the original code was an unencumbered neutron multiplication. While this was not thought to be a cause
for concern, it was quickly discovered that in multiplying the neutrons in the source volume as they were,
MCNP would quickly resign from tracking the sheer number of neutrons produced after only a few thousand
particles were run, as each one could produce additional fissions.
In an attempt to curb this rampant neutron multiplication, the original fixed source definition was
quickly replaced with a KCODE definition, which can be seen below:
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NRE 4232 Nuclear and Radiological Engineering p. 13/29 Spring 2015
Figure 10. KCODE for Source Model
The beauty in using the KCODE comes from being able to initially define the neutron multiplication
constant for the reactor otherwise known as the eigenvalue, and then maintaining the criticality within the range
of the specified parameter. All that is required from the user are a few initial run parameters and fission points.
In the first line after the word kcode come the parameters for number of particles per cycle, initial
eigenvalue, the number of particles to skip before averaging the eigenvalue, and finally the total number of
cycles to run. The line below it beginning with ksrc defines the initial spatial distribution of the fission points.
In the model the points form a 3d Cartesian axis directly through the very center of the cylindrical source.
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5.6.3. Fixed Source
As this KCODE model was unveiled, Dr. Petrovic strongly suggested the use of a fixed source instead
of the kcode citing the rampant multiplication of neutrons could be reduced through disabling any fission from
occurring within the source. This can be seen below in the current source definition, which incorporates a
NONU card, which treats all fission events as capture events instead.
Figure 11. Fixed Source Code with NONU Card
The source definition itself is created by defining some variables within the card. The first variable
ERG, defines the energy spectrum utilized by the source, in the model this is a Watt Fission Spectrum, exactly
the same as would be seen in a kcode. The second variable Cel defines the cells which are being treated as the
source. In the model, these represent the different components of the lattice structure. The rest of the variables
help define the cell within which the homogenized volumetric source resides. It is important to remember that
the cell defined here must encompass the entire source cell.
5.7. Heat Exchanger Partitions
In performing the flux to activation calculations, an important factor to take into account is how the heat
exchanger will have a higher activation near the bottom as opposed to the top. While the top of the heat
exchanger is expected to receive some flux, and in turn activate to the extent to which this happens will be
magnitudes less than what is experienced by the bottom. This is due in part to differences in distance from the
core and neutron flux being reduced exponentially as neutrons travel through the steel. To account for this and
to have the best possible tally information, the primary heat exchangers have been partitioned into graduated
length segments. While this has no effect on the functionality of the heat exchanger within the model, it does
allow for a better understanding of the flux distribution through the height of the heat exchanger.
The partitions vary from 2 cm segments to 50 cm and the planes defining the partitions can be seen in
the code below:
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20. X1. Heat Exchanger Activation
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Figure 12. Code for Heat Exchanger Partitioning
In the current model the flux tallies are only being calculated through the first 13 cells, allowing the
reduction of run time. Once more time can be dedicated to large, extensive runs, it is recommended that flux
tallies be performed across all partitions.
5.8. Mesh Tally
In understanding the flux distribution and to verify the neutrons are behaving as they should in the
model, mesh tallies were utilized to track the progress of neutrons through the reactor.
The code for the mesh tally can be found below:
Figure 13. Code for Mesh Tally Analysis
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Where the origin describes the starting point for the mesh tally, and the I, J, and K mesh terms describe how far
to take the mesh tally, discretized by cm units designated by the INTS terms. If one were to imagine this mesh, it
would be a full rectangular block that encompasses the entirety of the pressure vessel, not the bioshield.
However, it has a more defined resolution along the z axis rather than the x or y. These mesh tallies became
important later on when understanding how adding additional neutrons to each run would impact the distance
which flux could reach.
5.9. Variables to Change
In the final analysis model three independent variables were chosen, these included the vertical location
of the primary heat exchangers, the height of the reflector surrounding the core, and the boron concentration in
the water. As mentioned previously, extensive research was done in materials as well as shielding, ultimately
these were decided against and the three options above were selected.
In the final MCNP model, the vertical location of the heat exchangers is modified simply through
augmenting the z dimension of each box cell created in MCNP. However, the challenge comes when attempting
to push up the 50 planes that divide up the heat exchanger into tally segments. Fortunately through Microsoft
Excel, the text can be augmented off of a lynch pin number and each segment adjusted accordingly.
The proposed variations in vertical location are approximately 20 cm movements both above and below
the original location of the heat exchanger. With the 20 cm movements approximately 7 tally points should be
found for the heat exchanger. In terms of the reflector variation, the alteration of code becomes slightly trickier.
Because of the position of the core barrel connector ring, the reflector is immediately limited in the height it can
obtain. However, through advisement from Dr. Petrovic, the lower barrel can be extended, which in turn pushes
up the connector ring.
Figure 14. MCNP Model Showing Upper and Lower Barrel
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It is important to recognize, however, when the lower barrel is extended, if pressure vessel dimensions are to be
retained, the upper barrel length must be shortened. Fortunately with the current components included in the
MCNP model, augmenting the barrels imposes no problems upon any other components, the changes simply
involve changing cylinder heights and plane locations. These changes would be enacted upon cell block 1 and
2.
The final variable to change is the concentration of boric acid in the water card. Fortunately, this is
easily done through another homogenization process and well-placed comments. The varying concentrations for
borated water are commented out for now but, by quickly removing the comment designation symbol and
commenting out another water material card, the concentration is quickly and easily varied.
6. DESIGN CONSTRAINTS
As one of the design tasks of this project, the sensitivity of the activation of the primary heat exchangers
as a function of their axial distance to the core was analyzed, in addition to the effects of altering the height of
the radial reflector. For varying the axial distance of the heat exchangers, an increase and decrease in height of 2
feet was decided. This range was recommended by Dr. Petrovic and would theoretically be enough to produce a
sufficient sensitivity analysis of the activation of the heat exchanger. With increasing or decreasing the axial
distance of these components, there is also a concern for altering the locations of other components surrounding
them. In the model created in MCNP, the primary heat exchangers are situated approximately 2.3 meters or 7.54
feet above the lower barrel of the core. The top of the vessel in the model is located about 2.4 meters or 7.87 feet
above the top of the heat exchangers. However, there are pipes located both immediately above and below the
heat exchangers that act as inlets/outlets for the primary and secondary coolants. In addition, there are a total of
four pipes between every set of two heat exchangers that act as the decay heat removal system. These pipes are
700 mm in diameter and 7,300 mm in height and are longer than the primary heat exchangers. Because these
pipes are located in close vicinity of the heat exchangers, the range of ±2 feet is a realistic approximation as to
how much physical space is available for the axial movement of the heat exchangers.
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Figure 15. Decay Heat Removal System
In addition, the radial reflector will be extended in height to analyze its effect on heat exchanger
activation. As mentioned previously, the reflector spans the length of the core and is 405.8 cm tall in the model.
The reflector is then tightly surrounded by the lower section of the barrel. This introduces a minor obstacle in
increasing the height of the reflector, because the upper barrel is significantly smaller in diameter and is
positioned directly above both the reflector and lower barrel. Thus, when the height of the reflector and lower
barrel are increased, the length of the upper barrel will be decreased an equal amount. The height of the reflector
will be increased up until it reaches the bottom of the primary heat exchangers at approximately 665 cm.
7. FINAL DESIGN ANALYSIS AND EVALUATION
7.1. Final Model
As the semester progressed it was made readily evident that the amount of time to run each code was
increasing exponentially. With that knowledge in mind, the question was asked, does one compromise the
accuracy of the model for run efficiency or create an accurate model but forego run efficiency? Given the senior
design group is transient but the work itself is transitional, accuracy was decided as the focal point for the
model.
With this in mind, to date,zero flux has been recorded across any of the heat exchangers. The reasoning
for this is understood simply from the complexity of the model. Given neutrons along the Watt Spectrum have
to travel through almost three meters of water and layers of steel it’s understandable and expected that zero flux
would be recorded with such a low number of particle sampling. Low being a relative term, as most would
consider multibillion particle runs to be fairly significant, when compared to the activity magnitude in the core
of almost 1018
, almost 9 orders of magnitude greater than the number of particles run. However, given the
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tenacious nature of most Georgia Tech students, settling for zero results wasn’t enough. In an attempt to remedy
this, a few solutions were proposed and implemented.
The first solution to reduce run time and increase particle sampling was through having energy cutoffs
in different portions of the model. Specifically for the water regions outside of the core, anytime a neutron
enters with below 2 MeV, MCNP would immediately stop tracking the particle. This assumption was made
given that any neutron below 2 MeV would struggle to travel through the number of mean free paths entailed in
3 meters of water. By not accounting for these particles, the run time was reduced significantly, yet zero flux
was still being seen for the heat exchangers, even with running 2 billion particles!
The next solution to garner results was to reduce the scope of the discretized mesh tally. Initially, the
mesh tally was designed to surround the entire pressure vessel to get a visual representation of where in the
reactor was receiving flux. In sample models this mesh only need apply to the heat exchanger as that is the area
of significance in the scope of this project. However, even with this reduction in run time, zero flux was still
being received across the board even with some of the longer runs taking longer than 6 full days. Perhaps with
access to highly powerful computers that could run multiple parallel processes or servers that would allow for
month long uninterrupted runs, results could be found, but as of now with the limited computing resources at
hand it seems improbable any flux will be found. However, this leads into a perfect opportunity for any groups
in the future who wish to use the code and advance the research done to date.
Figure 16. 3D View of Final Model
7.2. TecPlot Models
Given the lack of flux found after running the MCNP, multiple trials have been run to see how
expanding the number of neutrons expands area within which flux is accounted for. Tecplot 360 models have
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been created to demonstrate this. Alongside each Tecplot model, a few numbers are calculated as well such as
the furthest x, y, and z points from the center of the core base. And also the furthest point where flux is seen
from the center based off total distance, found through the Pythagorean Theorem expanded into three
dimensions, with the accompanying flux at that location. These have been created for MCNP codes run with
nps of 1 million, 5 million, 25 million, 125 million, 500 million, 1 billion, 2 billion, 5 billion, and perhaps 10
billion.
5 Million
X Position 226.625
Y Position 238.875
Z Position 546.75
Furthest Point (79.625, 67.375,
546.75)
Distance from Center 556.6104
Flux at that Location 1.56 x 10-11
1 Million
X Position(cm) 214.375
Y Position(cm) 238.875
Z Position (cm) 425.25
Furthest Point (6.125, 202.125,
425.25)
Distance from Center (cm) 470.8817
Flux Tally (n/cm2) 1.18 x 10-9
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25 Million
X Position 238.875
Y Position 238.875
Z Position 546.75
Furthest Point (79.625, 67.375,
546.75)
Distance from Center 556.6104
Flux at that Location 3.13 x 10-12
125 Million
X Position 238.875
Y Position 238.875
Z Position 546.75
Furthest Point (6.125, 189.875,
546.75)
Distance from Center 578.814
Flux at that Location 1.71 x 10-14
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NRE 4232 Nuclear and Radiological Engineering p. 23/29 Spring 2015
500 Million
X Position 238.875
Y Position 238.875
Z Position 546.75
Furthest Point (6.125, 189.875,
546.75)
Distance from Center 578.814
Flux at that Location 4.28 x 10-15
1 Billion
X Position 238.875
Y Position 238.875
Z Position 546.75
Furthest Point (-128.625, -238.875,
546.75)
Distance from Center 610.3615
Flux at that Location 2.46 x 10-13
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2 Billion
X Position 238.875
Y Position 238.875
Z Position 546.75
Furthest Point (-226.625, -214.375,
546.75)
Distance from Center 629.4848
Flux at that Location 4.58 x 10-14
10 Billion
X Position 238.875
Y Position 238.875
Z Position 1032.75
Furthest Point (238.875, -
177.625,
1032.75
Distance from Center 1074.795
Flux at that Location 4.03 x 10-14
As can be seen above, with incremental increases to the nps, fluxes further and further from the bottom of the
core are achieved. With this idea in mind the question was asked,how many particles would have to be run for
particles to potentially reach the bottom of the heat exchanger,approximately 686.5095 cm. The assumption is
made that there is some causal relation between number of particles run and furthest point flux can reach in the
model. Based off of the numbers from the mesh tallies the following graph has been created to find an
exponential relationship between nps and distance, which can be found below:
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Figure X: Furthest Flux Distance from Core Base verse Particles Tracked
Extrapolating from the relationship found between the data, it is predicted that approximately 25 billion particles
would yield some sort of flux at the very bottom edge of the heat exchanger. Given the current capacity this run
is estimated to take 5 days. However,given a full distribution is desired throughout the heat exchanger,much
more than 25 billion particles would have to be run.
7.3. Future Design Plans
Given the complexity of the model, the majority of the research time has been primarily spent building
the model. Unfortunately, with such complex models the time required to run even just a billion particles can
take upwards of 6 days, based on the computer being utilized. Given the limited resources Georgia Tech
students have in terms of computer power, the primary resource being the Citrix servers provided by Georgia
Tech. This circumstance being understood, a few suggestions have been made on what could be done in place
of a robust MCNP model if time permitted.
The first suggestion would be to utilize particle splitting in regions of relatively high importance, simply
utilized as a variance reduction technique. Out of all the methodologies this one would most likely be easiest to
implement.
The second suggestion would be to create a deterministic model instead of using a Monte Carlo
radiation transport method such as with MCNP. Software suggestions along this vein include SCALE and also
CASMO & HELIOS. The reasoning for using deterministic software versus MCNP comes from the problems
to date. Due to model complexity, running a statistically significant number of particles is extremely time-
consuming. However, if these statistically significant numbers are not reached, no flux is shown in any of the
heat exchangers. With deterministic models even though the run times are typically longer than MCNP models,
an exact solution is guaranteed everywhere along the discretized mesh.
A third suggestion comes from attempting hand calculations. However, even in the most simplistic
solution of a 2-region/2-group problem, with an incoming current equivalent to that of the top of the core, can
take pages upon pages of calculations. Given the level of advanced mathematics required to solve these types of
problems, this solution would be recommended to those needing an initial calculation but also having a strong
math background. The other option along this branch would be to use a digital differential equation solver.
y = 1E-05e0.0516x
1.00E+00
1.00E+01
1.00E+02
1.00E+03
1.00E+04
1.00E+05
1.00E+06
1.00E+07
1.00E+08
1.00E+09
1.00E+10
1.00E+11
1.00E+12
400 450 500 550 600 650 700
NumberofNeutrons
Distance from Center (cm)
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The fourth and final alternative that can be taken is to produce an approximation of a two dimensional
slice of the pressure vessel. If looking at the reactor from above the situation would be similar to taking a sliver
of a pie chart.
Figure 14. 3D Representation of Slice Model
The justification for this approach comes from the assumption neutron flux is isotropic radially. With
this assumption in mind a simplistic model can be created by simply modeling a slice of the heat exchanger,
reactor vessel, barrel, etc. Any portion outside of the slice would be treated as a reflective surface to account for
any backscattering from other components. With this model in mind, a simple mesh tally can then be taken over
the volume or “area” of the heat exchanger. Unfortunately with the simplifications that all neutrons backscatter
and the flux is isotropic radially, the flux experienced by the heat exchanger would be much greater than what
would actually occur.
7.4. Suggestion for Future Work
This investigation on PHXR activation was performed over the course of 15 weeks. Due to this time
constraint, the objective was only to acquire the PHXR activation rate. Had there been more time allotted to this
project, an end application such as worker dose analysis could have been studied as well. However, with the
results as they are, the data presented can act as a foundation for future uses. For example, if one desired to
acquire the total dose a worker would receive standing directly atop the PHXR, a simple MCNP model utilizing
a cylindrical macro body of water alongside the PHXR model provided would suffice. The PHXR would also
need to be cut into multiple slices, to effectively model a correct activation distribution across the geometry of
the PHXR structure. This combined with a tally of choice would easily provide a general idea of the possible
dose deposition rates or values. Companies would benefit significantly by using the provided model to ascertain
the dose values that are possible during operation and thus in turn could assist reducing risk oriented costs for its
workers.
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8. ACKNOWLEDGEMENTS
This project would not have been possible without the help of Christopher Edgar, particularly with
modeling in MCNP. Chris met with our group for countless hours and gave us valuable insight on different
ways to approach our problem through MCNP.
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[References]
Flat Product Stainless Steel Grade Sheet. (2014). Retrieved February 5, 2015, from
http://www.northamericanstainless.com/wp-content/uploads/2010/10/Grade-316-316L.pdf
Bell, T. (2013). MetalProfile: Manganese. Retrieved February 5, 2015, from
http://metals.about.com/od/properties/a/Metal-Profile-Manganese.htm
Diehl, P. (1999). Neutron Activation Calculator. Retrieved January 25, 2015, from http://www.wise-
uranium.org/rnac.html
Memmott, M., Petrovic, B.,& Marchese,M. (2014). Integral Inherently Safe Light Water Reactor (I2S-LWR)
Concept: Integral VesselLayout. Proceedings of the 2014 International Congress on Advances in Nuclear
Power Plants.
Bell, J., Charry, C.,Dingman, N., DiMascio, P.,Hanley, B., & Powell, C. (2013). Microchannel Heat Exchanger
for Integral Pressurized Water Reactor. Georgia Tech Nuclear and Radiological Engineering Design.
"Cobalt-60m-decay" by Tubas-en - Own work. Licensed under Public Domain via Wikimedia
Commons - http://commons.wikimedia.org/wiki/File:Cobalt-60m-decay.svg#/media/File:Cobalt-60m-
decay.svg
"Cobalt | Radiation Protection | US EPA 2012
Zhou, Q., Yang, J., Wu, J., Tian, Y., Wang, J., Jiang, H., & Li, K. (2014). An improved algorithm to convert
CAD model to MCNP geometry model based on STEP file. Annals of Nuclear Energy, 78,81-88. Retrieved
from ELSEVIER.
Nyarku, Mawutorli, Ramanthapura S. Keshavamurthy, Venkata D. Subrmanian, Adish Haridas, and Eric T.
Glover. "Experimental Neutron Attenuation Measurements in Possible Fast Reactor Shield Materials." Georgia
Tech Library. Science Direct,26 Nov. 2012. Web.
R V Kolekar, R Kumar, and DN Sharma. “Shielding experiments for optimization of shield materials in
fast reactor using SSNTDs” Georgia Tech Library.Science Direct,3 Feb. 2013. Web.
I 2 S-LWR Burnable Absorbers Design Team G2 Andrew Conant, Casey McArthur,Gage Richert, Angelo
Spinetta, Aaron Tumulak 2014
Autodesk Inventor Modeling of Designed and Major Reactor Components Design Team 3D Brian Barron,
Matthew Marchese,Sterling Olson, PaulRose, Michael Saunders, Brian Schwartz 2013
http://alaquainc.com/Heat_Exchangers.aspx#Calcium_carbonate
Appendices
[Waterford 3 emails]
33. X1. Heat Exchanger Activation
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Pamela,
My son, Adnan, is requesting me to collect some info for his Nuclear Engineering Project at GA Tech. I will
appreciate if you or other nuclear engineers could answer to his questions noted below.
Thanks,
Joel M. Hashim
Senior Engineer/ Fire Protection Engineering
Engineering Programs & Components
Entergy, Waterford 3 Plant
(504) 739 - 6446
-----Original Message-----
From: Adnan Hashim [mailto:adnannhashim@gmail.com]
Sent: Tuesday, March 10, 2015 5:32 PM
To: Hashim, Joel; Joel Hashim
Subject: Senior design questions about Primary Heat Exchangers in LWR
EXTERNAL SENDER. DO NOT click links if sender is unknown. DO NOT provide your user ID or password.
Hey Dad,
My group and I would greatly appreciate it if you could help us find resources or exact values/documentation
about the Primary Heat Exchanger in your PWR at Waterford 3. We are working on a research design on an
experimental reactor known as the I2S-LWR (integral inherently safe light water reactor) for the univerisity.
These are some basic questions that imply more detailed questions following them.
Questions:
1) Estimated costs of producing one heat exchanger unit.
2) Company that produces the heat exchanger.
3) Information on printed circuit heat exchangers from a company known as Heatric
4) Estimated dose rate or activation rate of Waterford 3 heat exchangers from neutron leakage from the core
(neutron activation)
5) Any personnel or faculty that can provide more information about these questions.
6) Material composition of heat exchanger.
7) -Possible cost analysis of core reflector material and amount of material.
Sincerely grateful,
Adnan Hashim
2:
Adnan,
Are you asking about the steam generator? Or secondary side? That would make a big difference in the
questions you're asking. I'm not familiar with the I2S-LWR design.
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I've forwarded your email on to a system engineer who works with heat exchangers and he may be able to help
figure out what it is you're looking for.
As for the dose rate and activation questions, I'm not sure what you're looking for there. No heat exchanger is
directly impacted by neutrons to the point that we worry about activation or embrittlement. Dose rate issues are
mostly caused by crud buildup in the tubes if on the primary side (steam generator) and are not a concern in the
secondary system.
For the core reflector, the carbon steelvessel is lined with stainless steel and inside the primary shield wall that
is ~5.5' thick concrete. It is not actually credited in the design as a reflector though. Our core design is such that
the perimeter fuel assemblies are high burnup and act as our reflector leading to a center peaked power profile,
limiting neutron fluence on the vessel to preserve vessellife.
I've attached some of our system descriptions. The information they contain is not marked as proprietary or
security related, but I ask that you not widely distribute it or post it anywhere online.
3:
Pamela,
I greatly appreciate your response and also appreciate the attachments. I apologize for the confusion on the heat
exchangers. In our study case the I2S LWR being designed by a few universities as a hypothetical SMR has the
primary and decay heat exchangers integrated within the reactor vesselright outside the core barrelfor easy
transport. The objective of the reactor is to be able to be transported and replaced easily. I misconstrued the
question forgetting that standard PWRs do not incorporate primary coolant heat exchangers within the reactor
vessel. I apologize for the confusion.
The info you have provided is very useful and again I appreciate your time.
Sincerely,
Adnan Hashim
4: Kunkel
This is the information that I know.
1) Estimated costs of producing one heat exchanger unit. $175M
2) Company that produces the heat exchanger. Westinghouse Nuclear
3) Information on printed circuit heat exchangers from a company known as Heatric. Do not know
4) Estimated dose rate or activation rate of Waterford 3 heat exchangers from neutron leakage from the core
(neutron activation). We cannot access the generators at power due to dose. Based on known neutron dose
rates I estimate 10R and the lower portion ofthe generator.
5) Any personnel or faculty that can provide more information about these questions.
6) Material composition of heat exchanger. Inconel Alloy 690 tubes.
7) -Possible cost analysis of core reflector material and amount of material. We use thick (3-5 feet) concrete
walls for shielding.
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Keith Kunkel
5:
Mr. Kunkel,
I apologize for the late response but I’d like to to thank you for your time and the valuable information you have
provided. If you don’t mind, I’d also like to inquire the composition and quantity of “gunk” buildup in heat
exchangers mentioned to me by Pamela. Could you possibly expound on that?
Sincerely,
Adnan Hashim
Georgia Tech NRE class of 2016
6: Kunkel
We get a buildup of corrosion products on the secondary side of the steam generator. The primary side is all
stainless steel and remains clean.
7:
Mr. Kunkel,
Looking inside the primary coolant side steam generators/ heat exchangers,is there any activated steel or metal
particle build up? If so do you happen to know the quantity or their radiation effects?
Thanks,
Adnan Hashim
8: Kunkel
There is no buildup on the primary side. The primary water is kept extremely clean.