Master Theses & Projects (FESNS)

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https://ontariotechu.scholaris.ca/handle/10155/381

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The conceptualization and parameterization of a gaseous detector rasterizing pinhole gamma camera
(2016-08-01) Price, Terry J.; Machrafi, Rachid
This thesis details the conceptualization and parameterization of a gaseous detector rasterizing pinhole gamma camera. In this thesis, there is a literature review that describes the historical development of gamma imaging, a technical background that aims to give the reader the prerequisite background knowledge, a methodology, and, a result and discussion chapter. The thesis includes studies that determine if the concept of a gaseous detector rasterizing pinhole gamma camera is feasible, mathematical modeling that allowed for the exploration of the idea, software development that automated the mathematical modeling, parametric studies that explored the performance of various sets of design parameters, and, finally an iterative engineering design process that converged at a final set of design parameters. Ultimately, a set of design parameters, from which a prototype may be constructed, were developed.
Using MELCOR with enhanced predictive capabilities via Thermochimica to model two severe accident cases of a generic BWR with Zry-2 and FeCrAl
(2022-07-01) Breeden, Benjamin A. T.; Piro, Markus
The primary goal of this work was to enhance MELCOR’s material modelling capabilities via one-way coupling of Thermochimica. MELCOR is a state-of-the-art code used to simulate the severe accident progression of a nuclear power plant. The first objective was developing the capabilities in Thermochimica to handle the Ionic Two-sublattice Liquid Model in order to leverage the Thermodynamics of Advanced Fuels – International Database (TAF-ID). Using empirically derived data from the TAF-ID allowed Thermochimica to reliably predict the stable phases of nuclear materials and their composition. Secondly, two test case scenarios were simulated in MELCOR using a generic boiling water reactor design that included Case I: Zircaloy-2 cladding, and Case II: FeCrAl cladding. The results from these two cases were analyzed using a one-way coupling approach with Thermochimica to demonstrate potential areas for the improvement o fMELCOR’s current material modelling capabilities.
Study of LaBr3 (Ce) detector response to high energy helium ions
(University of Ontario Institute of Technology, 2022-04-01) Nayve, Christian; Machrafi, Rachid
The space radiation environment is a complex mixed field composed of neutral and charged particles such as photons, protons, alpha, and other particles. The mixture of these different particles creates a challenge in any accurate measurement with radiation detection devices. Lanthanum Bromide scintillator detector (LaBe3: Ce) has been successfully used as a gamma spectrometer inside space crafts. However, data on its response to other particles such as charged particles remains limited. From a radiation protection perspective, it is important to understand the response of the LaBr3 scintillator in the presence of heavy ions to provide more accurate measurements of the gamma fields within such a complex radiation environment. A series of Monte-Carlo simulations using MCNP/X version 2.6 have been performed along with a series of experiments using the Heavy Ion Medical Accelerator in Chiba, Japan. Measurements of the detector response function were conducted using He ion beams at various energies.
Development of neutron monitor for fusion systems
(2022-04-01) Li, Zhe; Machrafi, Rachid
Currently, the detection of neutrons employs sensors with a high thermal neutron response embedded in a thermalizing medium. However, this approach does not provide much information on neutron energy and, therefore, is inherently unable to identify sources commonly used in the industry. The current study proposes the use of a bi-atomic scintillator crystal, LaCl3, to detect fast neutrons above 1 MeV in general and develop a neutron monitor for (D, D) fusion reaction in particular. The approach uses the (n, p) reaction on a bi-atomic scintillator in the neutron energy range above 1 MeV. Thus, a series of Monte Carlo simulations have been performed using MCNP/X along with a series of experiments carried out using a neutron generator based on the (D, D) reaction at 106 n/s. Both sets of data were compared in term of the pulse height spectra. The analysis of the data suggests that a prominent peak from the emitted protons can serve to monitor the neutron emission from the generator.
Special isotopes of the FUGEN nuclear reactor
(2022-04-01) Davis, Timothy R.; Waller, Edward
The Canadian and Japanese nuclear regulatory bodies have shown dissimilarities between the isotopes considered to be of interest in decommissioning similarly styled heavy water reactors. This research examines the quantity of the isotopes that are of interest to the decommissioning of both the FUGEN nuclear power plant in Japan and the Pickering nuclear power plant in Canada and makes a comparison between them. This comparison is accomplished by modeling the fuel assemblies of both reactors in MCNP and performing depletion calculations on them to calculate the type and quantity of the produced fission and activation products, after which ratio comparisons are made between reactors. The FUGEN fuel has shown a greater isotope production than Pickering when normalized to fuel volume, with isotopes in FUGEN showing up to forty-five times the concentration when compared per unit volume with many isotopes produced in FUGEN not appearing in Pickering at all.
Study on heat transfer to supercritical water in application to SMRs
(2021-12-01) Dort-Goltz, Nikita; Pioro, Igor; McKellar, Jennifer
The SuperSafe Reactor (SSR), a small modular reactor (SMR) concept with a supercritical water coolant, was subjected to a thermalhydraulic analysis and an economic analysis of its Levelized Unit of Energy Cost (LUEC). Heat transfer data was examined for the onset of deteriorated heat transfer using three correlations that relied on NIST REFPROP v.10 for thermophysical property values. The experimental inside-wall temperature and heat transfer coefficient profiles were stable while the selected correlations generated poor predictions. NIST REFPROP v.10 was investigated at the critical point of water and the program was discovered to generate non-physical results. G4ECONS calculated the SSR’s LUEC, and when compared to other nuclear technologies, the SSR was among the least economically competitive. The application of several economic factors unique to SMRs helped reduce the SSR’s LUEC and increase its economic value. Overall, the SSR would be a technologically viable SMR concept with potential long-term industry adoption.
Improving x-ray operator performance using virtual environments
(2021-08-01) Breitinger, Mark; Waller, Ed
There are significant limitations in the training for x-ray operators under current regulatory and operational constraints. Advances in technology now allow for the creation of realistic virtual reality environments, which, when designed and implemented based on scientific principles and instructional system design concepts, can allow operators to test the full range of their tactics, techniques, and procedures. This research thesis presents novel synthetic virtual reality training environments for explosive ordnance disposal and security screening. This includes the development of physics simulation package for generating and imaging x-rays which can be applied in interactive, realistic and variable training environments for operators.
A study on the impact of global replacement of fossil fuel based electricity generation, transportation and domestic heating with nuclear generated electricity using a modified VENSIM DICE model
(2021-08-01) Shen, Huan; Tokuhiro, Akira
While much debated across current media, electricity generation using nuclear energy is proposed as one of the means of addressing the global negative impacts of climate change – notably ongoing accumulation of CO2 in the atmosphere by burning fossil fuels (FF). In this thesis, different transition scenarios were investigated in replacement of FF electricity generation, vehicle transport and domestic heating, using the macro-economic Dynamic Integrated Climate Economy (DICE) model. The model was modified by replacing FF sources by nuclear power plants, electric vehicles and heaters, across global scales. Based on declared national target year to attain net-zero carbon status, simulations were carried out based on parametric targets. Simulations results indicate that replacing all FF generation plants, vehicles and heaters would reduce CO2 emissions roughly 25%. For a net zero target of 2060, CO2 concentration will reduce by 82 ppm. This result predicts a reduction in global warming of 0.3°C by 2100.
Computational fluid dynamic investigations of flow through an aged CANDU pressure tube
(2021-08-01) Lu, Zheng; Piro, Markus
Single-phase, isothermal computational fluid dynamics simulations of twelve simplified CANDUTM 37M fuel bundles sitting in both as-received and aged pressure tubes were performed with Hydra in this work. The predicted coolant flow behaviour of two cases were compared in order to investigate the impact of pressure tube deformation (sag and diametral expansion) on coolant flow. The boundary conditions and material properties are representative of normal operating conditions in a high-powered channel of the Darlington Nuclear Generating Station. Rigorous mesh and turbulence model sensitivity analyses have been performed in this work. It has been determined that pressure tube deformation has a significant impact on coolant flow behaviour, whereby up to 25% of flow bypasses the fuel. The reduced flow within the subchannels of the fuel bundles impacts the coolability of the fuel.
Development and demonstration of a high-performance Gaussian puff model for nuclear emergency training scenarios in unity game engine
(2021-08-01) Gelautz, Paul David; Waller, Edward
Prompt decision making and implementation of protective actions in the event of a nuclear or radiological emergency require detailed preparations and training. Computer models provide an avenue to simulate the presence of radioactive sources and/or releases of radioactive material safely, but the calculations involved can be complex and time- consuming. Increasing computer processing power and advanced coding techniques allow for complex simulations to be performed in real time while maintaining a level of performance suitable for modern interactive applications. A real-time dispersion model with simulation time scaling has been developed that provides a platform for creating training scenarios for the emergency response decision making process for radiological and nuclear emergencies. This research explores the development of this Gaussian puff model capable of calculating high-resolution radionuclide deposition maps and is demonstrated in an interactive training application.
Characterization of PVA-Borax-fructose gel for the capture of radioactive wastes generated during nuclear decommissioning activities
(2021-05-01) Sarvendran, Vajran Timothy; Harvel, Glenn
With the long-term objective of using polymer gels for the capture of solid, liquid and gaseous waste generated from decommissioning works, characterization of gel properties as well as the properties of the individual constituents of polymer gels has been completed. Characteristics of constituents were investigated over varied concentrations and environments. Preliminary thermal degradation characterization found no adverse hysteresis behaviour regarding the polymer constituent. Constituent chemistry as well as chemistry that enables crosslinking between constituents was examined, and the theory that most accurately describes the crosslinking of constituents was established. Understanding of chemistry and characterization results were employed to successfully manufacture varied gels, with varied applications. Variation of gels were achieved via adjustments, primarily to polymer concentrations.
Detector integration of severe accident management instrumentation for robotic applications at nuclear reactor facilities
(2021-08-01) Nusrat, Omar; Waller, Edward
In the aftermath of a nuclear accident, robots can be used to monitor and assess radiological contamination, preventing harmful exposure to plant personnel. In this work, several detectors were evaluated to be supplemented onto the Husky UGV. Specifically, the RadEye Gamma Survey Meter, the PurpleAir Air-Quality (PA) sensor, and the NaI(Tl) scintillator were examined and their measurement parameters optimized. Optimization was done to satisfy mitigation requirements outlined in regulatory severe accident management guidelines (SAMGs). A software component (Severe Accident Radioactivity Classification; SARC) was developed with the detector components, facilitating detector integration and analysis to aid emergency responders. For the RadEye, 20 seconds was determined to be the optimal collection time; the long term stability and short-term sensitivity of the PA was evaluated; and two spectra measured with the NaI(Tl) were examined. Future work involves further integration of SARC and the addition of advanced capabilities such as infrastructure damage detection.
Study of radio frequency inductively coupled thermal plasma torch (RF ICPT) for radioactive waste treatment: thermoplastics - polyethylene and polyvinyl chloride (PVC)
(2021-06-01) Hassen, Isaac; Gaber, Hossam
Despite advancements in technology and many progresses made in effort for radioactive waste (RW) treatment and overall management, there is still no final and ever lasting solution. Among the many RW materials originating from nuclear power plants (NPPs), thermoplastics such as polyvinyl chloride (PVC) and polyethylene (PE) contribute significant amount to the overall volume of RW. The presence of radioactive nuclides in PVC and PE waste originating from NPPs and their plastic nature (non-bio-degradable characteristics) present two challenges at once. To solve the challenges presented by such plastic RW, a thermal plasma waste treatment approach was considered. A radiofrequency (RF) inductively coupled plasma torch (ICPT) was designed in SOLIDWORKS and simulated using COMSOL Multiphysics software, and its thermal behavior was studied. Its applicability including advantages and shortcomings for such use was studied.
Analysis and optimal planning of nuclear-renewable hybrid energy systems for ships
(2021-06-01) Adham, Md Ibrahim; Gaber, Hossam
Ocean-going ships are one of the sources of global GHG emissions. Several actions are being taken to reduce the GHG emissions from maritime vessels, and integration of Renewable Energy Sources (RESs) is one of them. Due to some limitations, RESs are not suitable for large ships and often mix with fossil fuel-based generators. Fossil fuel-based generators need to be replaced by emissions-free energy sources to make marine ships free from emissions. Nuclear energy is emissions-free, and small-scale nuclear reactors like Microreactors (MRs) have the potential to replace fossil fuel-based generators. In this study, the technical, economic, and environmental competitiveness of Nuclear-Renewable Hybrid Energy Systems (N-R HES) in marine ships are assessed. The results determine that N-R HES has the lowest NPC compared to the other conventional energy systems. A sensitivity analysis is carried out to see the impact of different system parameters on this study's findings.
Study of contaminants in plasmas during decommissioning processes
(2020-12-01) Somer, Nicholas; Harvel, Glenn
With the intention of eventual development of on-site radionuclide capture technologies, methods to simulate radionuclide behaviour when contaminated components are subjected to plasma-based decommissioning processes are developed. Two parallel plasma systems are developed and investigated. A better-understood argon plasma based system has temperature measurement methods developed, along with an exploration of the resultant behavior when non-radioactive isotopes of cesium iodide contaminants are introduced. This plasma system produces traces of ionic species of cesium and iodide, as well as space-dependent deposition patterns: both of which are relevant towards understanding behaviour of contaminants in environments undergoing decommissioning processes. A physical simulation of a cutting process of a contaminated component is completed using an commercial plasma torch by cutting cesium iodide contaminated samples. This process produces some of the same ionic species as in the controlled experiment, proving a controlled argon plasma can be used to simulate plasma environments in decommissioning scenarios.
Evaluation of the bubble spectrometer performance in space-like neutron fields
(2021-02-01) Montague, Talon James; Machrafi, Rachid
The Space Bubble Detector Spectrometer (SBDS) consists of six bubble detectors each with a different neutron energy threshold. To characterize the spectrometer in a space-like neutron field, a series of experiments were conducted with high-energy neutrons from 6.0×105 eV to 7.50 ×108 eV at the Los Alamos National Laboratory. The analysis of the obtained data provided a calibration factor to adjust the neutron sensitivity, to high-energy neutrons of the SBDS, based on its response function matrix. The results suggest that the SBDS underestimates the ambient dose equivalent in a space-like neutron field by a factor of approximately 1.55. Consequently, the readings of the spectrometer should be adjusted when used in a space radiation environment. This thesis is dedicated to studying the SBDS in a space-like neutron spectrum. It outlines a part of the results of international ground testing experimental sessions of the space instrumentation supported by the Canadian Space Agency.
Planning and optimization of nuclear-renewable micro hybrid energy systems for off-grid applications
(2020-11-01) Abdussami, Md Rafiul; Gaber, Hossam
Resilient operation of medium/large scale off-grid energy systems is a key challenge for energy crisis solutions, which requires continuous and sustainable energy resources. In this context, microreactors are incorporated with renewables to provide a continuous, reliable, and sustainable energy supply. The research is apportioned into two parts. In the first part, the study proposes three methods of hybridization for planning and identifying the most efficient Nuclear-Renewable Micro Hybrid Energy System (N-R MHES). Based on proposed hybridization techniques, mathematical modeling of N-R MHES's economy is carried out. An artificial intelligence optimization technique is used to achieve the optimal system configurations of different N-R MHESs and determine the best hybridized nuclear-renewable system. In the second portion of the study, a traditional technology, diesel-fired Micro Energy Grid (MEG), is compared with the best configured N-R MHES. This study of the comparison indicates that microreactor-based MEGs could be a potential replacement for diesel-fired MEGs.
Experimental investigations of thermodynamic properties of the LiF –CsF binary system and FliNaK
(2020-07-01) Lipkina, Ksenia; Piro, Markus H.A.
Generation IV nuclear power technologies, including various molten salt reactor designs are considered to accommodate growing energy needs with minimal impact on the environment. The development of the molten salt reactor class highly depends on understanding molten fluoride salt physicochemical properties, which are studied and verified by reviewing existing data coupled with modern experimental techniques. Experimental investigations of thermodynamic properties of several fluorides were performed to fill knowledge gaps identified in the thermodynamics of fluoride salts. A custom crucible design, selection of suitable calibrants, sample preparation refinement, benchmarking, qualification, and new experimental measurements have been performed. Crucibles worked well for phase transition measurements, benchmarking results gave confidence in developed procedures, capabilities and limitations of the proposed approach were also identified. New measurements of the LiF –CsF system filled some knowledge gaps on the melting behaviour and revealed an additional phase that was not previously reported in the open literature.
Towards low dose retrospective dosimetry on shelled species
(2020-08-01) Hassan, Amna; Waller, Ed
This work investigates calcified tissues of shelled species for retrospective dosimetry using electron paramagnetic resonance (EPR) spectroscopy. To determine applicable samples for low dose studies, shells of crustacean and mollusc species were irradiated to 10 Gy using a 137Cs source. Reference dosimetry was performed with alanine powder using a specifically developed calibration curve. Characteristic Mn2+ signals were present in the EPR spectra of all studied species. Radiation induced peaks were not detected in shells of any species except terrestrial snails. A dose-response curve for terrestrial snails was developed by irradiating shells to 2, 10, and 20 Gy. However, Mn2+ signals caused limitations in resolving radiation induced peaks below 2 Gy. Environmental factors were assessed, and it was found that shell structure and habitat characteristics contribute to Mn2+ signals in EPR spectra. Since high-intensity Mn2+ signals obscured radiation-induced peaks, shells of the studied aquatic species were deemed unsuitable for low dose retrospective dosimetry.
Local dose coefficients for radionuclide contamination in wounds
(2020-05-01) Galipeau, Natasha; Waller, Ed
The objective of this research is to create local dose coefficients for radionuclide contaminated wounds to accompany dose coefficients obtained by Oak Ridge Institute for Science and Education looking at whole body effects of radionuclide intake from wounds. These dose coefficients can be used to calculate activity limits at the wound site that could lead to a clinically significant dose. This is useful for emergency response to assist in decisions on decorportaion therapy. Wound models were created for injections, lacerations, abrasions, and burns and MCNP was used to simulate the dose received by 38 radionuclides. Mathematical models accounted for biological removal of the radionuclides from the wound site. It was found that radionuclides that are not retained well at the wound site are likely of little concern locally, but for highly retained radionuclides local doses may be concerning.

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