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Dissertations / Theses on the topic 'Pebble bed reactors – Cooling'

Author: Grafiati

Published: 4 June 2021

Last updated: 8 February 2022

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1

Ruppersberg, Johannes Coenraad. "Transient modelling of a loop thermosyphon : transient effects in single and two phase natural circulation thermosyphon loops suitable for the reactor cavity cooling of a pebble bed modular reactor." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20858.

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Thesis (MScIng)--University of Stellenbosch, 2008.<br>ENGLISH ABSTRACT: The focus of this project was the application of a passive device in the form of a loop thermosyphon as a reactor cavity cooling system (RCCS) for a Pebble Bed Modular Reactor. An extensive literature review showed that loop thermosyphons have been widely researched, both theoretically and experimentally. In the review attention has specifically been given to matters such as safety, instability, control and mathematical modelling. One of the objectives of the project was to build one of the axially symmetric sections

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2

Verwey, Aldo. "Modelling of a passive reactor cavity cooling system (RCCS) for a nuclear reactor core subject to environmental changes and the optimisation of the RCCS radiation heat shield heat shield." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4303.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: A reactor cavity cooling system (RCCS) is used in the PBMR to protect the concrete citadel surrounding the reactor from direct nuclear radiation impingement and heat. The speci ed maximum operating temperature of the concrete structure is 65 ±C for normal operating conditions and 125 ±C for emergency shut-down conditions. A conceptual design of an entirely passive RCCS suitable for the PBMR was done by using closed loop thermosyphon heat pipes (CLTHPs) to remove heat from a rad

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3

Sittmann, Ilse. "Inside-pipe heat transfer coefficient characterisation of a one third height scale model of a natural circulation loop suitable for a reactor cavity cooling system of the Pebble Bed Modular Reactor." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6708.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2011.<br>ENGLISH ABSTRACT: The feasibility of a closed loop thermosyphon for the Reactor Cavity Cooling System of the Pebble Bed Modular Reactor has been the subject of many research projects. Difficulties identified by previous studies include the hypothetical inaccuracies of heat transfer coefficient correlations available in literature. The aim of the research presented here is to develop inside-pipe heat transfer correlations that are specific to the current design of the RCCS. In order to achieve t

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4

Oosthuizen, Philip Rudolf. "Thermal-fluid simulation investigation of the reactor cavity cooling system standpipes design for the pebble bed modular reactor / P.R. Oosthuizen." Thesis, North-West University, 2003. http://hdl.handle.net/10394/518.

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Pebble Bed Modular Reactors are advanced nuclear reactors and are being developed to possess inherent safety and reliability. This is achieved by utilizing a sequence of passive thermal storage and heat transfer mechanisms, to perform long term decay heat removal. The Reactor Cavity Cooling System (RCCS) facilitates this long term decay heat removal. The purpose of this study was to develop a one-dimensional, homogeneous two-phase flow model in order to perform investigative thermal-fluid studies on the concept designs of the standpipes of a typical RCCS system, such as that proposed for PBMR

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5

Van, der Merwe David-John. "Experimental and numerical investigation of the heat transfer between a high temperature reactor pressure vessel and the outside of the concrete confinement structure." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71796.

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Thesis (MScEng)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: A high temperature reactor (HTR) generates heat inside of the reactor core through nuclear fission, from where the heat is transferred through the core and heats up the reactor pressure vessel (RPV). The heat from the RPV is transported passively through the reactor cavity, where it is cooled by the reactor cavity cooling system (RCCS), through the concrete confinement structure and ultimately into the environment. The concrete confinement structure can withstand temperatures of up to 65°C for normal operating conditions

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6

Lebenhaft, Julian R. (Julian Robert) 1954. "MCNP4B modeling of pebble-bed reactors." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/28288.

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Thesis (Nucl.E. and S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, February 2002.<br>Includes bibliographical references (v. 1, leaves 152-171).<br>The applicability of the Monte Carlo code MCNP4B to the neutronic modeling of pebblebed reactors was investigated. A modeling methodology was developed based on an analysis of critical experiments carried out at the HTR-PROTIEUS and ASTRA facilities, and the critical loading of the HTR-10 reactor. A body-centred cubic lattice of spheres with a specified packing fraction approximates the pebble bed, and exclusion zones o

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7

Abejón, Orzáez Jorge. "Neutronics analysis of a modified Pebble Bed Advanced High Temperature Reactor." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1238045558.

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8

Yesilyurt, Gokhan. "Numerical simulation of flow distribution for pebble bed high temperature gas cooled reactors." Texas A&M University, 2004. http://hdl.handle.net/1969.1/372.

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The premise of the work presented here is to use a common analytical tool, Computational Fluid dynamics (CFD), along with a difference turbulence models. Eddy viscosity models as well as state-of-the-art Large Eddy Simulation (LES) were used to study the flow past bluff bodies. A suitable CFD code (CFX5.6b) was selected and implemented. Simulation of turbulent transport for the gas through the gaps of the randomly distributed spherical fuel elements (pebbles) was performed. Although there are a number of numerical studies () on flows around spherical bodies, none of them use the necessary turb

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9

Movalo, Raisibe Shirley. "Fuel management study for a pebble bed modular reactor core." Thesis, Stellenbosch : Stellenbosch University, 2010. http://hdl.handle.net/10019.1/4234.

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Thesis (MSc (Physics))--Stellenbosch University, 2010.<br>ENGLISH ABSTRACT: This dissertation reports on the impact of a set of selected nuclear fuel management parameters on reactor operations of the PBMR core. This is achieved by performing an assessment of the impact of nuclear fuel management parameter variations on the most important safety and economics issues for the PBMR core. These include the maximum fuel temperature at steady state and during Depressurized Loss of Forced Cooling (DLOFC) accident conditions. The reactivity worth of the Reactor Control System (RCS which determin

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10

Mashau, Sharon Ntevheleni. "The preparation of pitches from anthracene oil." Pretoria : [S.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-06242008-075035/.

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11

Yurko, Joseph Paul. "Effect of helium injection on diffusion dominated air ingress accidents in pebble bed reactors." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62711.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 73-74).<br>The primary objective of this thesis was to validate the sustained counter air diffusion (SCAD) method at preventing natural circulation onset in diffusion dominated air ingress accidents. The analysis presented in this thesis starts with a vertically oriented rupture of a coaxial pipe. Air enters into the reactor cavity at a rate dictated by diffusion, until the buoyancy force is strong enough to in

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12

Hanlon-Hyssong, Jaime E. "Modularity of the MIT Pebble Bed Reactor for use by the commercial power industry." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/10945/3701.

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CIVINS<br>The Modular Pebble Bed Reactor is a small high temperature helium cooled reactor that is being considered for both electric power and hydrogen production. Pebble bed reactors are being developed in South Africa, China and the US. To make smaller 120 Mwe reactors economically competitive with larger 1500 Mwe traditional light water reactors changes in the way these plants are built are needed. Economies of production need to be sufficiently large to compete with economies of scale. MIT (Berte) has been working on developing a modular design and construction strategy for several

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13

Mkhosi, Margaret Msongi. "Computational fluid dynamics analysis of aerosol deposition in pebble beds." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180536054.

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14

Zamxaka, Lwandiso Lindani. "The impact of quality management systems during a pebble bed modular reactor project. A case study." Thesis, Cape Peninsula University of Technology, 2010. http://hdl.handle.net/20.500.11838/1226.

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Thesis(Mtech (Industrial Engineering)--Cape Peninsula University of Technology, 2010<br>In the nuclear industry, Quality Management Systems are extremely important, especially if one wishes to improve public acceptance of radioactive solutions. There is normally minimum communication between the public and scientists, especially in nuclear science. People are not comfortable with nuclear technology, based on the past history of the Chernobyl catastrophe. Consequently, it is difficult to discuss important and sensitive issues like disposing of nuclear waste. Quality Management Systems can

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15

Papakokkinos, Giorgos. "Computational modeling of adsorption packed bed reactors and solar-driven adsorption cooling systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/672099.

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Environmental concerns regarding climate change and ozone depletion urge for a paradigm shift in the cooling production. The cooling demand exhibits an alarmingly increasing trend, thus its satisfaction in a sustainable manner is imperative. Adsorption cooling systems (ACSs) are a potential candidate for a sustainable future of cooling production, since they can utilize solar energy or waste heat, as well as they can employ substances with zero ozone depletion and global warming potential. The objective of this thesis is to contribute to the investigation and improvement of ACSs, through the d

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16

Khoza, Samukelisiwe Nozipho Purity. "Characteristic behaviour of pebble bed high temperature gas-cooled reactors during water ingress events / Samukelisiwe Nozipho Purity Khoza." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8706.

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The effect of water ingress in two pebble bed high temperature gas-cooled reactors i.e. the PBMR-200 MWthermal and the PBMR-400 MWthermal were simulated and compared using the VSOP 99/05 suite of codes. To investigate the effect of this event on reactivity, power profiles and thermal neutron flux profiles, the addition of partial steam vapour pressures in stages up to 400 bar into the primary circuit for the PBMR-400 and up to 300 bar for the PBMR- 200 was simulated for both reactors. During the simulation, three scenarios were simulated, i.e. water ingress into the core only, water ingress in

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17

Van, der Meer Willem Arie. "Modelling long–range radiation heat transfer in a pebble bed reactor / vanderMeer W.A." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7595.

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Through the years different models have been proposed to calculate the total effective thermal conductivity in packed beds. The purpose amongst others of these models is to calculate the temperature distribution and heat flux in high temperature pebble bed reactors. Recently a new model has been developed at the North–West University in South Africa and is called the Multi–Sphere Unit Cell (MSUC) model. The unique contribution of this model is that it manages to also predict the effective thermal conductivity in the near wall region by taking into account the local variation in the porosity. W

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18

Visser, Coert Johannes. "Modelling heat and mass flow through packed pebble beds a heterogeneous volume-averaged approach /." Pretoria : [s.n.], 2007. http://upetd.up.ac.za/thesis/available/etd-08292008-125630/.

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19

Bollen, Rob. "Verification and validation of computer simulations with the purpose of licensing a pebble bed modular reactor." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53216.

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Thesis (MBA)--Stellenbosch University, 2002.<br>ENGLISH ABSTRACT: The Pebble Bed Modular Reactor is a new and inherently safe concept for a nuclear power generation plant. In order to obtain the necessary licenses to build and operate this reactor, numerous design and safety analyses need to be performed. The results of these analyses must be supported with substantial proof to provide the nuclear authorities with a sufficient level of confidence in these results to be able to supply the required licences. Beside the obvious need for a sufficient level of confidence in the safety analyses, the

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20

Serfontein, Dawid Eduard. "Deep burn strategy for the optimized incineration of reactor waste plutonium in pebble bed high temperature gas–cooled reactors / Serfontein D.E." Thesis, North-West University, 2013. http://hdl.handle.net/10394/8069.

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In this thesis advanced fuel cycles for the incineration, i.e. deep–burn, of weapons–grade plutonium, reactor–grade plutonium from pressurised light water reactors and reactor–grade plutonium + the associated Minor Actinides in the 400 MWth Pebble Bed Modular Reactor Demonstration Power Plant was simulated with the VSOP 99/05 diffusion code. These results were also compared to the standard 9 g/fuel sphere U/Pu 9.6% enriched uranium fuel cycle. The addition of the Minor Actinides to the reactor–grade plutonium caused an unacceptable decrease in the burn–up and thus an unacceptable increase in t

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21

Geringer, Josina Wilhelmina. "The influence of the number of fuel passes through a pebble bed core on the coupled neutronics / thermalhydraulics characteristics / by Wilna Geringer." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4729.

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The increasing demand for energy and the effect on climate change are some of the big drivers in support of the nuclear renaissance. A great amount of energy is spent on studies to determine the contribution of nuclear power to the future energy supply. Many countries are investing in generation III and IV reactors such as the Westinghouse AP1000 because of its passive cooling system, which makes it attractive for its safety. The pebble bed high temperature gas cooled reactors are designed to be intrinsically safe, which is one of the main drivers for developing these reactors. A pebble bed re

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22

Wilke, Charel Daniel. "Experimental measurement of graphite wear in helium at elevated temperatures and the discrete element modelling of graphite dust production inside the Pebble Bed Modular Reactor." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80211.

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Thesis (MScEng)--Stellenbosch University, 2013.<br>ENGLISH ABSTRACT: Production of graphite dust inside the Pebble Bed Modular Reactor (PBMR) influences the reactor operation negatively. Graphite is used as a moderator in the reactor core and the formation and transportation of graphite dust away from the reactor core decreases the amount of moderator which in turn has a negative impact on the reactor operation. High levels of radioactive dust may also contaminate reactor components which may pose a health risk to maintenance personnel. In this study a pressure vessel was designed and u

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23

De, Villiers Gerrit Johannes. "In-core temperature measurement for the PBMR using fibre-bragg gratings." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2867.

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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.<br>The PBMR has called for research into the possibility of distributed in-core temperature measurement. In this thesis, several methods for distributed temperature measurement in high-pressure, -radiation and -temperature environments have been investigated by means of a literature study. The literature study has revealed FBG temperature sensors as the most feasible solution to the temperature measurement challenge. Various parameters affecting the propagation of light in optical fibres and conse

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24

Oswald, Elbrecht. "Indirect measurement of reactor fuel temperature." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4145.

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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: Regulators and designers of nuclear reactors regard knowledge of the pebble fuel temperature as important, due to the role that it plays in maintaining structural integrity and the production of neutrons. By using special fuel assemblies fitted with measuring equipment it is possible to measure the fuel temperature in stationary fuel reactors. This, however, is not possible in the pebble bed modular reactor due to its dynamic core. Designers of the pebble bed modular reactor h

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25

Gougar, Hans David. "Advanced core design and fuel management for pebble-bed reactors." 2004. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-451/index.html.

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26

Chang, Won-Pyo. "Two-phase cooling of a simulated fuel debris bed." 1985. http://catalog.hathitrust.org/api/volumes/oclc/12228191.html.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1985.<br>Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 214-221).

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27

Tyobeka, Bismark Mzubanzi. "Advanced multi-dimensional deterministic transport computational capability for safety analysis of pebble-bed reactors." 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2121/index.html.

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28

Van, der Merwe Jacobus Johannes. "Verification and validation of the PBMR models and codes used to predict gaseous fission product releases from spherical fuel elements." Thesis, 2008. http://hdl.handle.net/10210/430.

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The fission product releases from spherical fuel elements used in modern high temperature gas cooled reactors are one of the first source terms used in describing the safety of planned nuclear plants during normal and accident conditions. The verification and validation of the model and code used to predict the gaseous fission product behaviour and release from spherical fuel elements for the PBMR were documented in this dissertation. The PBMR is the latest design in high temperature gas cooled reactor technology utilizing spherical fuel elements based on the LEU TRISO-coated particle design.

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29

Visser, Coert Johannes. "Modelling heat and mass flow through packed pebble beds : a heterogeneous volume-averaged approach." Diss., 2008. http://hdl.handle.net/2263/27623.

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This work details modelling buoyancy-driven viscous flow and heat transfer through heterogeneous saturated packed pebble beds via a set of volume-averaged conservation equations in which local thermal disequilibrium is accounted for. The latter refers to the two phases considered viz. solid and fluid, differing in temperature. This is effected by describing each phase with its own governing equation. Further to the aforementioned, the governing equation set is written in terms of intrinsic volume-averaged material properties that are fully variant with respect to temperature. The heterogeneous

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30

Sedumoeng, Lillian M. "Deterministic analysis for the sensitivity of Licensing Basis Events (LBE) radiological consequences to various exposure pathways for the Pebble Bed Modular Reactor (PMBR) / Lillian M. Sedumoeng." Thesis, 2004. http://hdl.handle.net/10394/11316.

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Nuclear safety is the main concern for the licensing of nuclear power plants, not only in the Republic of South Africa but also worldwide. The design of the nuclear power plant plays an important role in the licensing process, which includes probabilistic and deterministic analysis of a set of design or Licensing basis events. This study was about the deterministic analysis for the sensitivity of licensing basis events radiological consequences to different radiological pathways. The study was done for the Pebble Bed Modular Reactor (PBMR), which is a nuclear power plant, still in its early ph

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31

Oosthuizen, Marita. "An evaluation of a public participation process for fairness and competence." Thesis, 2008. http://hdl.handle.net/10210/659.

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Public participation can be defined as ...”a process leading to a joint effort by stakeholders, technical specialists, the authorities and the proponent who work together to produce better decisions than if they had acted independently" (Greyling, 1999, p. 20). In South Africa, public participation processes are legally driven and form part a statutory part of environmental impact assessments. Many environmental impact assessments have been undertaken in South Africa, but the environmental impact assessment undertaken for the proposed construction of a demonstration module pebble bed modular r

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