Academic literature on the topic 'Pebble bed reactors – Temperature'
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Journal articles on the topic "Pebble bed reactors – Temperature"
1
Rostamian, M., S. Arifeen, G. P. Potirniche, and A. Tokuhiro. "Initial prediction of dust production in pebble bed reactors." Mechanical Sciences 2, no. 2 (2011): 189–95. http://dx.doi.org/10.5194/ms-2-189-2011.
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Abstract. This paper describes the computational simulation of contact zones between pebbles in a pebble bed reactor. In this type of reactor, the potential for graphite dust generation from frictional contact of graphite pebbles and the subsequent transport of dust and fission products can cause significant safety issues at very high temperatures around 900 °C in HTRs. The present simulation is an initial attempt to quantify the amount of nuclear grade graphite dust produced within a very high temperature reactor.
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Song, Shixiong, Xiangzhou Cai, Yafen Liu, Quan Wei, and Wei Guo. "Pore Scale Thermal Hydraulics Investigations of Molten Salt Cooled Pebble Bed High Temperature Reactor with BCC and FCC Configurations." Science and Technology of Nuclear Installations 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/589895.
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The present paper systematically investigated pore scale thermal hydraulics characteristics of molten salt cooled high temperature pebble bed reactor. By using computational fluid dynamics (CFD) methods and employing simplified body center cubic (BCC) and face center cubic (FCC) model, pressure drop and local mean Nusselt number are calculated. The simulation result shows that the high Prandtl number molten salt in packed bed has unique fluid-dynamics and thermodynamic properties. There are divergences between CFD results and empirical correlations’ predictions of pressure drop and local Nusselt numbers. Local pebble surface temperature distributions in several default conditions are investigated. Thermal removal capacities of molten salt are confirmed in the case of nominal condition; the pebble surface temperature under the condition of local power distortion shows the tolerance of pebble in extreme neutron dose exposure. The numerical experiments of local pebble insufficient cooling indicate that in the molten salt cooled pebble bed reactor, the pebble surface temperature is not very sensitive to loss of partial coolant. The methods and results of this paper would be useful for optimum designs and safety analysis of molten salt cooled pebble bed reactors.
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Englert, Matthias, Friederike Frieß, and M. V. Ramana. "Accident Scenarios Involving Pebble Bed High Temperature Reactors." Science & Global Security 25, no. 1 (2017): 42–55. http://dx.doi.org/10.1080/08929882.2017.1275320.
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Wan, Xin, Ximing Liu, Jichen Miao, Peng Cong, Yuai Zhang, and Zhifang Wu. "Research on the Computed Tomography Pebble Flow Detecting System for HTR-PM." Science and Technology of Nuclear Installations 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/5403701.
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Pebble dynamics is important for the safe operation of pebble-bed high temperature gas-cooled reactors and is a complicated problem of great concern. To investigate it more authentically, a computed tomography pebble flow detecting (CT-PFD) system has been constructed, in which a three-dimensional model is simulated according to the ratio of 1 : 5 with the core of HTR-PM. A multislice helical CT is utilized to acquire the reconstructed cross-sectional images of simulated pebbles, among which special tracer pebbles are designed to indicate pebble flow. Tracer pebbles can be recognized from many other background pebbles because of their heavy kernels that can be resolved in CT images. The detecting principle and design parameters of the system were demonstrated by a verification experiment on an existing CT system in this paper. Algorithms to automatically locate the three-dimensional coordinates of tracer pebbles and to rebuild the trajectory of each tracer pebble were presented and verified. The proposed pebble-detecting and tracking technique described in this paper will be implemented in the near future.
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Sun, Sida, Hong Li, and Sheng Fang. "The Optimization of Radiation Protection in the Design of the High Temperature Reactor-Pebble-Bed Module." Science and Technology of Nuclear Installations 2017 (2017): 1–15. http://dx.doi.org/10.1155/2017/3984603.
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The optimization of radiation protection is an important task in both the design and operation of a nuclear power plant. Although this topic has been considerably investigated for pressurized water reactors, there are very few public reports on it for pebble-bed reactors. This paper proposes a routine that jointly optimizes the system design and radiation protection of High Temperature Reactor-Pebble-Bed Module (HTR-PM) towards the As Low As Reasonably Achievable (ALARA) principle. A systematic framework is also established for the optimization of radiation protection for pebble-bed reactors. Typical calculations for the radiation protection of radioactivity-related systems are presented to quantitatively evaluate the efficiency of the optimization routine, which achieve 23.3%~90.6% reduction of either dose rate or shielding or both of them. The annual collective doses of different systems are reduced through iterative optimization of the dose rates, designs, maintenance procedures, and work durations and compared against the previous estimates. The comparison demonstrates that the annual collective dose of HTR-PM is reduced from 0.490 man-Sv/a before optimization to 0.445 man-Sv/a after optimization, which complies with the requirements of the Chinese regulatory guide and proves the effectiveness of the proposed routine and framework.
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Liem, P. H. "Design procedures for small pebble-bed high temperature reactors." Annals of Nuclear Energy 23, no. 3 (1996): 207–15. http://dx.doi.org/10.1016/0306-4549(95)00018-1.
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Yang, Xingtuan, Yu Li, Nan Gui, Xinlong Jia, Jiyuan Tu, and Shengyao Jiang. "Some Movement Mechanisms and Characteristics in Pebble Bed Reactor." Science and Technology of Nuclear Installations 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/820481.
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The pebblebed-type high temperature gas-cooled reactor is considered to be one of the promising solutions for generation IV advanced reactors, and the two-region arranged reactor core can enhance its advantages by flattening neutron flux. However, this application is held back by the existence of mixing zone between central and peripheral regions, which results from pebbles’ dispersion motions. In this study, experiments have been carried out to study the dispersion phenomenon, and the variation of dispersion region and radial distribution of pebbles in the specifically shaped flow field are shown. Most importantly, the standard deviation of pebbles’ radial positions in dispersion region, as a quantitative index to describe the size of dispersion region, is gotten through statistical analysis. Besides, discrete element method has been utilized to analyze the parameter influence on dispersion region, and this practice offers some strategies to eliminate or reduce mixing zone in practical reactors.
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Bakhshayesh, Moshkbar, and Naser Vosoughi. "A simulation of a pebble bed reactor core by the MCNP-4C computer code." Nuclear Technology and Radiation Protection 24, no. 3 (2009): 177–82. http://dx.doi.org/10.2298/ntrp0903177b.
Full textAbstract:
Lack of energy is a major crisis of our century; the irregular increase of fossil fuel costs has forced us to search for novel, cheaper, and safer sources of energy. Pebble bed reactors - an advanced new generation of reactors with specific advantages in safety and cost - might turn out to be the desired candidate for the role. The calculation of the critical height of a pebble bed reactor at room temperature, while using the MCNP-4C computer code, is the main goal of this paper. In order to reduce the MCNP computing time compared to the previously proposed schemes, we have devised a new simulation scheme. Different arrangements of kernels in fuel pebble simulations were investigated and the best arrangement to decrease the MCNP execution time (while keeping the accuracy of the results), chosen. The neutron flux distribution and control rods worth, as well as their shadowing effects, have also been considered in this paper. All calculations done for the HTR-10 reactor core are in good agreement with experimental results.
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Ekariansyah, Andi Sofrany, Surip Widodo, Hendro Tjahjono, Susyadi Susyadi, Puradwi Ismu Wahyono, and Anwar Budianto. "PRELIMINARY ANALYSIS OF CORE TEMPERATURE DISTRIBUTION OF EXPERIMENTAL POWER REACTOR USING RELAP5." JURNAL TEKNOLOGI REAKTOR NUKLIR TRI DASA MEGA 20, no. 3 (2018): 159. http://dx.doi.org/10.17146/tdm.2018.20.3.4665.
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High Temperature Gas Cooled Reactor (HTGR) is a high temperature reactor type having nuclear fuels formed by small particles containing uranium in the core. One of HTGR designs is Pebble Bed Reactor (PBR), which utilizes helium gas flowing between pebble fuels in the core. The PBR is also the similar reactor being developed by Indonesia National Nuclear Energy Agency (BATAN) under the name of the Reaktor Daya Eksperimental (RDE) or Experimental Power Reactor (EPR) started in 2015. One important step of the EPR program is the completion of the detail design document of EPR, which should be submitted to the regulatory body at the end of 2018. The purpose of this research is to present preliminary results in the core temperature distribution in the EPR using the RELAP5/SCDAP/Mod3.4 to be complemented in the detail design document. Methodology of the calculation is by modelling the core section of the EPR design according to the determined procedures. The EPR core section consisting of the pebble bed, outlet channels, and hot gas plenum have been modelled to be simulated with 10 MWt. It shows that the core temperature distribution under assumed model of 4 core zones is below the limiting pebble temperature of 1,620 °C with the highest pebble temperature of 1,477.0 °C. The results are still preliminary and requires further researches by considering other factors such as more representative radial and axial power distribution, decrease of core mass flow, and heat loss to the reactor pressure vessel.Keywords: Pebble bed, core temperature, EPR, RELAP5 ANALISIS AWAL DISTRIBUSI TEMPERATUR TERAS REAKTOR DAYA EKSPERIMENTAL MENGGUNAKAN RELAP5. High Temperature Gas Cooled Reactor (HTGR) adalah reaktor tipe temperatur tinggi yang memiliki bahan bakar nukir dalam bentuk bola-bola kecil yang mengandung uranium. Salah satu desain HTGR adalah reaktor pebble bed (Pebble bed reactor/PBR) yang memanfaatkan gas helium sebagai pendingin yang mengalir di celah-celah bahan bakar bola di dalam teras. PBR juga merupakan tipe reaktor yang sedang dikembangkan oleh BATAN dengan nama reaktor daya eksperimental (RDE) yang dimulai pada 2015. Salah satu tahapan penting dalam program RDE adalah penyelesaian dokumen desain rinci yang harus dikirimkan ke badan pengawas pada akhir 2018. Tujuan penelitian adalah untuk menyajikan hasil-hasil awal pada distribusi temperatur di teras RDE menggunakan RELAP5/SCDAP/Mod3.4 sehingga dapat melengkapi isi dokumen desain rinci. Metode perhitungan adalah dengan memodelkan bagian teras RDE sesuai hasil penelitian sebelumnya. Bagian teras RDE yang dimodelkan terdiri dari pebble bed, kanal luaran, dan plenum gas bawah yang disimulasikan pada daya 10 MWt. Hasil simulasi menunjukkan bahwa distribusi temperatur teras dengan asumsi pembagian 4 zona teras mendapatkan temperatur tertinggi sebesar 1477 °C yang masih di bawah batasan temperatur di bola bahan bakar yaitu 1620 °C. Hasil yang diperoleh masih estimasi awal dan membutuhkan penelitian lebih lanjut dengan mempertimbangkan faktor-faktor lainnya seperti distribusi daya aksial dan radian yang lebih representatif, pengurangan aliran teras, dan kehilangan panas teras yang diserap oleh bejana reaktor.Kata kunci: Pebble bed, temperatur teras, RDE, RELAP5
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Bai, Yuyu, Nan Gui, Xingtuan Yang, Jiyuan Tu, and Shengyao Jiang. "Computational fluid dynamics investigation of thermal-hydraulic characteristics in a simplified pebbled bed modular reactor core using different arrangements of fuel elements." Journal of Computational Multiphase Flows 10, no. 3 (2017): 119–27. http://dx.doi.org/10.1177/1757482x17746923.
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High-temperature gas-cooled reactor is a kind of advanced nuclear reactor in which the core is packed with spherical fuel elements. In high-temperature gas-cooled reactors, the operating temperature is higher than that in ordinary light water reactors. In an attempt to analyze the flow pattern and heat transfer situation to provide reference for the safe operation of the pebble bed reactors, a segment of simplified high-temperature gas-cooled reactor core is simulated with computational fluid dynamics method. Four kinds of arrangement, including simple cubic, body-centered cubic, face-centered cubic, and a combination structure of body-centered cubic and face-centered cubic, are studied, respectively. Based on the simulation results, higher heat transfer capability and lower pebble temperature are obtained in the case with the most compact arrangement. The drag coefficient ( Cd) for four arrangements with different inlet Reynolds number (Re) is obtained and relationship between Re and Cd is analyzed. In addition, a simulation with a broken fuel element in the body-centered cubic fluid domain has been performed. The results show that the presence of broken fuel may result in uneven flow, which will change the heat transfer condition. So it is better to avoid broken fuel element in a high-temperature gas-cooled reactor.
Dissertations / Theses on the topic "Pebble bed reactors – Temperature"
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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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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 determines the shutdown capability of the reactor core and the average discharge
burn-up of fuel are also established. The fuel management parameters considered in this
study include different enrichment levels, heavy metal loadings and fuel sphere
circulation regimes. The impact and importance of these parameters on plant safety and
economics is assessed. The dissertation will report the effects on the standard core
physics parameters such as power peaking, multiplication factor, burn-up (safety and
economics) and derive the benefits and drawbacks from the results. Based upon the
findings from this study, and also experimental data, an optimum fuel management
scheme is proposed for the PBMR core.<br>AFRIKAANSE OPSOMMING: Hierdie verhandeling beskryf die uitwerking van ‘n gekose stel kernbrandstofparameters
op die bedryf van die PBMR reaktor. Die impak wat variasies in kernbrandstofparameters
op belangrike veiligheids- en ekonomiese oorwegings het, is tydens hierdie studie
ondersoek. Van die belangrikste oorwegings is die maksimum brandstoftemperatuur
tydens normale, konstante bedryf, asook gedurende ‘n “Depressurized Loss of Forced
Cooling (DLOFC)” insident waar alle verkoeling gestaak word. Ander belangrike fasette
wat ondersoek is, is die reaktiwiteitwaarde van die beheerstelsel (RCS), wat die aanleg se
vermoë om veilig af te sluit bepaal, asook die totale kernverbruik van die brandstof. Die
kernbrandstofparameters wat in ag geneem is, sluit die brandstofverryking,
swaarmetaalinhoud en die aantal brandstofsirkulasies deur die reaktorhart in. Die
belangrikheid en impak van elk van hierdie parameters is ondersoek en word in die
verhandeling beskryf . Daar word verslag gelewer oor die voor- en nadele, asook die
uitwerking van hierdie variasies op standaard reaktorfisika-parameters soos
drywingspieke in die brandstof, neutronvermenigvuldigingsfaktore en kernverbuik van
die brandstof, vanaf ‘n veiligheids- en ekonomiese oogpunt. Gebaseer op die
gevolgtrekkings van hierdie studie, tesame met eksperimentele data, word ‘n optimale
kernbrandstofbestuurprogram voorgestel.
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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 turbulence models that are required to simulate flow where strong separation
exists. With the development of high performance computers built for applications that
require high CPU time and memory; numerical simulation becomes one of the more
effective approaches for such investigations and LES type of turbulence models can be
used more effectively.
Since there are objects that are touching each other in the present study, a special
approach was applied at the stage of building computational domain. This is supposed to
be a considerable improvement for CFD applications. Zero thickness was achieved
between the pebbles in which fission reaction takes place.
Since there is a strong pressure gradient as a result of high Reynolds Number on
the computational domain, which strongly affects the boundary layer behavior, heat
transfer in both laminar and turbulent flows varies noticeably. Therefore, noncircular
curved flows as in the pebble-bed situatio n, in detailed local sense, is interesting to be
investigated.
Since a compromise is needed between accuracy of results and time/cost of effort
in acquiring the results numerically, selection of turbulence model should be done
carefully. Resolving all the scales of a turbulent flow is too costly, while employing
highly empirical turbulence models to complex problems could give inaccurate
simulation results. The Large Eddy Simulation (LES) method would achieve the
requirements to obtain a reasonable result. In LES, the large scales in the flow are solved
and the small scales are modeled.
Eddy viscosity and Reynolds stress models were also be used to investigate the
applicability of these models for this kind of flow past bluff bodies at high Re numbers.
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Abejon, Orzaez Jorge. "Neutronics analysis of a modified Pebble Bed Advanced High Temperature Reactor." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1238045558.
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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 the heavy metal
(HM) content in the spent fuel, which is intended for direct disposal in a deep geological
repository, without chemical reprocessing. All the Pu fuel cycles failed the adopted safety
limits in that either the maximum fuel temperature of 1130°C, during normal operation, or the
maximum power of 4.5 kW/sphere was exceeded. All the Pu cycles also produced positive
Uniform Temperature Reactivity Coefficients, i.e. the coefficient where the temperature of the
fuel and the graphite moderator in the fuel spheres are varied together. these positive
temperature coefficients were experienced at low temperatures, typically below 700°C. This
was due to the influence of the thermal fission resonance of 241Pu. The safety performance of
the weapons–grade plutonium was the worst. The safety performance of the reactor–grade
plutonium also deteriorated when the heavy metal loading was reduced from 3 g/sphere to 2
g or 1 g.
In view of these safety problems, these Pu fuel cycles were judged to be not licensable in the
PBMR DPP–400 reactor. Therefore a redesign of the fuel cycle for reactor–grade plutonium,
the power conversion system and the reactor geometry was proposed in order to solve these
problems. The main elements of these proposals are:
v
1. The use of 3 g reactor–grade plutonium fuel spheres should be the point of departure.
232Th will then be added in order to restore negative Uniform Temperature Reactivity
Coefficients.
2. The introduction of neutron poisons into the reflectors, in order to suppress the power
density peaks and thus the temperature peaks.
3. In order to counter the reduction in burn–up by this introduction of neutron poisons, a
thinning of the central reflector was proposed.<br>Thesis (PhD (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.
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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 into the reflectors only
and water ingress into both the core and reflectors. The induced reactivity change
effects were compared for these reactors.
An in-depth analysis was also carried out to study the mechanisms that drive the
reactivity changes for each reactor caused by water ingress into the fuel core only,
the riser tubes in the reflectors only and ingress into both the fuel core and the riser
tubes in the reflectors.
The knowledge gained of these mechanisms and effects was used in order to
propose design changes aimed at mitigating the reactivity increases, caused by
realistic water ingress scenarios. Past results from simulations of water ingress into
Pebble Bed Reactors were used to validate and verify the present simulation
approach and results. The reactivity increase results for both reactors were in
agreement with the German HTR-Modul calculations.<br>Thesis (MSc (Engineering Sciences in Nuclear Engineering))--North-West University, Potchefstroom Campus, 2013
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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
have reserved special inspection channel borings inside the center reflector for
fuel temperature measurement. By means of optical fibers and interferometry,
the temperature can be measured inside such a channel. Currently the only way
to control the fuel surface and core temperature is by measuring the gas inlet
and outlet temperatures.
This thesis attempts to determine the pebble temperature by measuring the
temperature in a reflector channel. This is done by constructing an electrically
heated pebble bed experimental setup simulating a cutout section of a pebble
bed modular reactor core. An additional computational fluid dynamics simulation
of the experimental setup was also performed. This thesis also attempts to
determine if there is a measureable temperature peak that can indicate where a
pebble was in contact with the reflector surface. This could then be used in
future studies to determine the pebble fuel velocity as it moves down the reactor
core.
The computational fluid dynamics results were validated by experimental
measurements. In the computational fluid dynamics model and experimental
setup, it was found that there was indeed a measureable temperature difference
on the temperature gradient along the reflector wall. The heat being conducted
away from the pebble through the contact area can explain this. These
differences were only observed when the channel was moved closer to the pebbles and it is therefore advised that some redesigning of the channel should
be done if the in-core temperature is to be accurately interpreted by the
designers at PBMR (Pty) Ltd.<br>AFRIKAANSE OPSOMMING: Reguleerders en ontwerpers van kern reaktore beskou die kennis van die korrel
brandstof temperatuur as belangrik. Dit is weens die rol wat die brandstof
temperatuur speel met die behoud van strukturele integriteit en die produksie
van neutrone binne-in die reaktor. Met behulp van spesiale brandstof montasies
toegerus met die meetings instrumentasie, is dit moontlik om die brandstof
temperatuur in stilstaande brandstof reaktore te meet. Dit is egter nie moontlik
in die korrel bed modulêre reaktor nie, as gevolg van sy dinamiese kern.
Ontwerpers van die korrel bed modulêre reaktor het spesiale kanale in die
binnekant van die middel reflektor vir brandstof temperatuur meeting
gereseveer. Deur middel van optiese vesel en interferometrie, kan die
temperatuur binne so 'n kanaal gemeet word. Tans is die enigste manier om die
brandstof-oppervlak temperatuur te berekern, net moontlik deur gebruik te
maak van die gemete gas inlaat-en uitlaat temperature van die reaktor.
Hierdie tesis poog om vas te stel of die korrel brandstof temperatuur deur die
meet van die oppervlak temperatuur in 'n reflektor-kanaal bepaal kan word. Dit
word gedoen deur 'n elektriese verhitte korrel bed eksperimentele opstelling te
bou wat 'n gedeelte van 'n korrel bed modulêre reaktor simuleer. 'n Bykomende
numeriese simulasie van die eksperimentele opstelling was ook uitgevoer.
Hierdie werk het ook probeer om vas te stel of daar 'n meetbare temperatuur
piek op die temperatuur profiel aandui kan word waar 'n korrel in kontak is met
die reflektor se oppervlak. Dit kan dan in toekomstige studies gebruik word om
te bepaal wat die korrel brandstof spoed was soos dit in die reaktor beweeg.
Die numerise simulasie uitslae was deur eksperimentele metings bevestig. In die
numerise simulasie model en die eksperimentele opstelling, is daar gevind dat
daar inderdaad 'n meetbare temperatuur verskil op die temperatuurgradiënt
teen die reflektor oppervlak is. Dit kan verduidelik word as gevolg van die hitte wat weg van die korrel gelei word deur middel van die kontak area. Hierdie
verskille was slegs waargeneem wanneer die kanaal nader aan die korrels geskuif
is en dit word as n aanbeveling aan PBMR (Pty) Ltd gemaak om sommige
herontwerpe aan die kanaal te doen indien die in-kerntemperatuur gemeet wil
word en akkuraat geinterpreteer wil word.
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Anderson, Jennifer Marie 1977. "Analysis of the proliferation resistance of the modular pebble bed high temperature gas reactor." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9558.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1999.<br>Includes bibliographical references (leaf 46).<br>The Modular Pebble Bed High Temperature Gas Reactor (MPBR) being designed by the Massachusetts Institute of Technology and the Idaho National Engineering and Environmental Laboratory operates with an online refueling system. This leads to an increased risk of proliferation because the fuel pebbles can be diverted while the plant is operating. In order to show that the MPBR dose not pose a proliferation risk the fuel content was determined for different burnups up to 94 MWD/kg. This data shows that the fuel is very poor nuclear weapon material. Safeguard systems were also designed in agreement with the International Atomic Energy Agency's standards to prevent diversion of significant quantities of fissile material.<br>by Jennifer Marie Anderson.<br>S.B.
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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 reactor is a high temperature reactor which is helium–cooled and graphitemoderated
using spherical fuel elements that contain triple–coated isotropic fuel particles
(TRISO). The success of its intrinsic safety lies in the design of the fuel elements that remain
intact at very high temperatures. When temperatures significantly higher than 1600 °C are
reached during accidents, the fuel elements with their inherent safety features may be challenged.
A pebble bed reactor has an online fuelling concept, where fuel is circulated through the core.
The fuel is loaded at the top of the core and through gravity, moves down to the bottom where it
is unloaded to either be discarded or to be re–circulated. This is determined by the burnup
measuring system. By circulating the fuel spheres more than once through the reactor a flattened
axial power profile with lower power peaking and therefore lower maximum fuel temperatures
can be achieved. This is an attractive approach to increase the core performance by lowering the
important fuel operating parameters. However, the circulation has an economic impact, as it
increases the design requirements on the burnup measuring system (faster measuring times and
increased circulation). By adopting a multi–pass recycling scheme of the pebble fuel elements it is
shown that the axial power peaking can be reduced
The primary objective for this study is the investigation of the influences on the core design with
regards to the number of fuel passes. The general behaviour of the two concepts, multi–pass
refuelling and a once–through circulation, are to be evaluated with regards to flux and power and
the maximum fuel temperature profiles. The relative effects of the HTR–Modul with its
cylindrical core design and the PBMR 400 MW with its annular core design are also compared to
verify the differences and trends as well as the influences of the control rods on core behaviour.
This is important as it has a direct impact on the safety of the plant (that the fuel temperatures
need to remain under 1600 °C in normal and accident conditions). The work is required at an
early stage of reactor design since it influences design decisions needed on the fuel handling system design and defuel chute decay time, and has a direct impact on the fuel burnup–level
qualification.
The analysis showed that in most cases the increase in number of fuel passes not only flattens the
power profile, but improves the overall results. The improvement in results decreases
exponentially and from ten passes the advantage of having more passes becomes insignificant.
The effect of the flattened power profile is more visible on the PBMR 400 MW than on the
HTR–Modul. The 15–pass HTR–Modul design is at its limit with regards to the measuring time of
a single burnup measuring system. However, by having less passes through the core, e.g. tenpasses,
more time will be available for burnup measurement. The PBMR 400 MW has three
defuel chutes allowing longer decay time which improves measurement accuracy, and, as a result
could benefit from more than six passes without increasing the fuel handling system costs.
The secondary objective of performing a sensitivity analysis on the control rod insertion
positions and the effect of higher fuel enrichment has also been achieved. Control rod efficiency
is improved when increasing the excess reactivity by means of control rod insertion. However,
this is done at lower discharge burnup and shut down margins. Higher enrichment causes an
increase in power peaking and more fuel–passes will be required to maintain the peaking and
temperature margins than before.<br>Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.
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Gintner, Stephan Konrad. "Thorium–based fuel cycles : saving uranium in a 200 MWth pebble bed high temperature reactor / S.K. Gintner." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4581.
Full textAbstract:
The predominant nuclear fuel used globally at present is uranium which is a finite resource. Thorium has been identified as an alternative nuclear fuel source that can be utilized in almost all existing uranium–based reactors and can significantly help in conserving limited uranium reserves. Furthermore, the elimination of proliferation risks associated with thorium–based fuel cycles is a key reason for re–evaluating the possible utilization of thorium in high temperature reactors. In addition to the many advantages that thorium–based fuel has over uranium–based fuel, there are vast thorium resources in the earth's crust that up until the present have not been exploited optimally.
This study focuses on determining the amount of uranium ore that can be saved using thorium as a nuclear fuel in HTR's. Four identical 200 MWth high temperature reactors are considered which make use of different fuel cycles. These fuel cycles range from the conventional uranium fuel cycle to a thorium–based fuel cycle in which no U–238 is present and have been simulated using the VSOP–A system of computer codes. This study also considers the effect that protactinium, an isotope that occurs in thorium–based fuel cycles, will have on the decay heat production in the case of a depressurized loss of coolant (DLOFC) accident.<br>Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2011.
Books on the topic "Pebble bed reactors – Temperature"
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Boer, Brian. Optimized core design and fuel management of a pebble-bed type nuclear reactor. IOS Press, 2008.
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A, Verrall R., Atomic Energy of Canada Limited., and Chalk River Laboratories. Fuel Development Branch, eds. Post-irradiation examination of BEATRIX-II phase-II Li2ZrO3 pebble-bed. Fuel Development Branch, Chalk River Laboratories, 1996.
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(Germany), Arbeitsgemeinschaft Versuchsreaktor, Kernforschungsanlage Jülich, and VDI-Gesellschaft Energietechnik, eds. AVR, 20 Jahre Betrieb: Ein deutscher Beitrag zu einer zukunftsweisenden Energietechnik : Tagung Aachen, 17. und 18. Mai 1989. VDI-Verlag, 1989.
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Hsu, Chia-Chang. Kinetic study of Si(NH) synthesis via low temperature vapor phase reaction of SiCl and NH in a fluidized bed reactor. 1994.
Find full textBook chapters on the topic "Pebble bed reactors – Temperature"
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Suikkanen, Heikki, Ville Rintala, and Juhani Hyvärinen. "DEM in Analyses of Nuclear Pebble Bed Reactors." In Springer Proceedings in Physics. Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-1926-5_122.
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Kolios, Grigorios, Achim Gritsch, Bernd Glöckler, and Gerhart Eigenberger. "Enhancing Productivity and Thermal Efficiency of High-Temperature Endothermic Processes in Heat-Integrated Fixed-Bed Reactors." In Integrated Chemical Processes. Wiley-VCH Verlag GmbH & Co. KGaA, 2005. http://dx.doi.org/10.1002/3527605738.ch1.
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Reitsma, Frederik. "Pebble Bed Gas Cooled Reactors." In Encyclopedia of Nuclear Energy. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-12-819725-7.00188-4.
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Megiris, C. E., and J. B. Butt. "EFFECTS OF POISONING ON THE DYNAMICS OF FIXED BED REACTORS: Cyclic and Temperature-Increased Operational Policies." In Tenth International Symposium on Chemical Reaction Engineering. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-08-036969-3.50077-4.
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Doraiswamy, L. K. "Reactor Design for Solid-Catalyzed Fluid-Phase Reactions." In Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0019.
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Catalytic reactions are carried out in reactors with a fixed, fluidized, or moving bed of catalyst. Although the chemical kinetics of the reaction obviously remains the same for all these reactors, the hydrodynamic features vary considerably. Because no complete description of these features is possible, it is convenient to postulate different situations and develop mathematical models to represent these situations for each type of reactor. It is also important to note that wherever solid catalysts are used, the question of catalyst deactivation cannot be ignored. Several books and reviews covering a variety of situations have been written, including those marked with an asterisk in the list of references. They are recommended for general reading. Our intention in this chapter is limited, however: formulate approaches to the design of two main classes of catalytic reactors, fixed and fluidized bed; briefly describe selected procedures along with a few numerical (or methodological) examples to illustrate their use; and outline a procedure for incorporating the effects of catalyst deactivation in reactor design and operation. There are basically two types of fixed-bed reactors: (1) multitubular, in which tubes of approximately 1.5 to 4.0 cm in diameter are placed as a bundle within a shell through which a heat exchange fluid is circulated to control the temperature profile within the reactor; and (2) adiabatic, in which the catalyst is placed directly inside a reactor (with no a priori limitation to the diameter), and heat removal is accomplished by multistaging the bed and removing the heat of reaction by heat exchange between stages. Four major models have been proposed for describing the behavior of a packed tubular reactor (see Doraiswamy and Sharma, 1984). Of these, the most extensively used is the quasi-continuum model in which the fluid-solid system is assumed to act as a single pseudohomogeneous phase with effective properties of its own (as for any true single phase). Thus the procedures developed in Chapters 4 and 10 for the homogeneous model can be used to determine the axial profiles of concentration and temperature. One can also allow for radial transport gradients within each tube [two-dimensional (2-D) models], as opposed to the simpler models in which these gradients are neglected—the one-dimensional (1-D) models.
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Kovalenko, Galina, and Larisa Perminova. "Heterogeneous Biocatalysts for the Final Stages of Deep Processing of Renewable Resources into Valuable Products." In Molecular Biotechnology [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.89411.
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Heterogeneous biocatalysis is a part of biotechnology and it has commercial potential for industrial implementation, in particular the final stages of deep processing of renewable raw materials. The commercially attractive heterogeneous biocatalysts are prepared by immobilizing practically valuable enzymatic active substances onto solid inorganic supports. Heterogeneous biocatalytic processes of the target conversion of substrate into valuable market product are carried out in periodic or continuous modes using traditional batch and packed-bed reactors, as well as novel types of vortex reactors in accordance with the principles of green chemistry. Heterogeneous biocatalysts for the final stages of deep processing of vegetable raw materials such as starch and oils are described here. One of the biocatalysts is glucoamylase immobilized by adsorption on mesoporous carbon support Sibunit™ type. This glucoamylase-active biocatalyst is used at the stage of starch saccharification, i.e., hydrolysis of dextrin to treacle and glucose syrups used in food and confectionary industries. The second of the biocatalysts is recombinant T. lanuginosus lipase immobilized on mesoporous silica KSK™ type and macroporous carbon aerogel. These lipase-active biocatalysts can effectively compete with traditional organic synthesis catalysts, and they are used in low-temperature processes carried out in unconventional anhydrous media such as interesterification of vegetable oils’ triglycerides with ethyl acetate for producing ethyl esters of fatty acids (biodiesel and vitamin F) and esterification of fatty acids with aliphatic alcohols for synthesis of various esters used as fragrances, flavorings, odors, emollients, and nonionic surfactants in perfume and cosmetics industries. The prepared heterogeneous biocatalysts due to their high enzymatic activity and operational stability are promising for practical implementation.
Conference papers on the topic "Pebble bed reactors – Temperature"
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Cogliati, Joshua J., and Abderrafi M. Ougouag. "Pebble Bed Reactor Dust Production Model." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58289.
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The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.
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Serfontein, Dawid, Eben Mulder, and Eberhard Teuchert. "Proposal for an International Experimental Pebble Bed Reactor." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58174.
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HTRs, both prismatic block fuelled and pebble fuelled, feature a number of uniquely beneficial characteristics that will be discussed in this paper. In this paper the construction of an international experimental pebble bed reactor is proposed, possible experiments suggested and an invitation extended to interested partners for co-operation in the project. Experimental verification by nuclear regulators in order to facilitate licensing and the development of a new generation of reactors create a strong need for such a reactor. Suggested experiments include: • Optimized incineration of waste Pu in a pebble bed reactor: The capability to incineration pure reactor grade plutonium by means of ultra high burn-up in pebble bed reactors will be presented at this conference in the track on fuel and fuel cycles. This will enable incineration of the global stockpile of separated reactor grade Pu within a relatively short time span; • Testing of fuel sphere geometries, aimed at improving neutron moderation and a decrease in fuel temperatures; • Th/Pu fuel cycles: Previous HTR programs demonstrated the viability of a Th-232 fuel-cycle, using highly enriched uranium (HEU) as driver material. However, considerations favoring proliferation resistance limit the enrichment level of uranium in commercial reactors to 20%, thereby lowering the isotopic efficiency. Therefore, Pu driver material should be developed to replace the HEU component. Instead of deploying a (Th, Pu)O2 fuel concept, the proposal is to use the unique capability offered by pebble bed reactors in deploying separate Th- and Pu-containing pebbles, which can be cycled differently; • Testing of carbon-fiber-carbon (CFC) structures for in-core or near-core applications, such as guide tubes for reserve shutdown systems, thus creating the possibility to safely shutdown reactors with increased diameter; • Development of very high temperature reactor components for process heat applications; • Advanced decay heat removal systems e.g. design specific air flow channels, or heat pipe designs external to the reactor pressure vessel; • Development of a plutonium fuelled peaking reactor with the proposed duel cycle; • A radial coolant flow pattern with increased power output; • Testing of carbon-fiber-carbon (CFC) core barrel applications. The design will facilitate ease of licensing by sacrificing performance in favor of safety and employing redundant defense-in-depth safety systems. Speedy licensing is therefore expected. The economic model will be based on a commercial expedition of the agreed experimental value to collaborating participants. Target costs will be minimized by exploiting known technology only and by utilizing off-the-shelf components as far as possible.
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In, Wang-Kee, Won-Jae Lee, and Yassin A. Hassan. "CFD Simulation of a Coolant Flow and a Heat Transfer in a Pebble Bed Reactor." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58334.
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This CFD study is to simulate a coolant (gas) flow and heat transfer in a PBR core during a normal operation. This study used a pebble array with direct area contacts among the pebbles which is one of the pebbles arrangements for a detailed simulation of PBR core CFD studies. A CFD model is developed to more adequately represent the pebbles randomly stacked in the PBR core. The CFD predictions showed a large variation of the temperature on the pebble surface as well as in the pebble core. The temperature drop in the outer graphite layer is smaller than that in the pebble-core region. This is because the thermal conductivity of graphite is higher than the fuel (UO2 mixture) conductivity in the pebble core. Higher pebble surface temperature is predicted downstream of the pebble contact due to a reverse flow. Multiple vortices are predicted to occur downstream of the spherical pebbles due to a flow separation. The coolant flow structure and fuel temperature in the PBR core appears to largely depend on the in-core distribution of the pebbles.
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Boer, B., J. L. Kloosterman, D. Lathouwers, T. H. J. J. van der Hagen, and H. van Dam. "Optimization of a Radially Cooled Pebble Bed Reactor." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58117.
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By altering the coolant flow direction in a pebble bed reactor from axial to radial, the pressure drop can be reduced tremendously. In this case the coolant flows from the outer reflector through the pebble bed and finally to flow paths in the inner reflector. As a consequence, the fuel temperatures are elevated due to the reduced heat transfer of the coolant. However, the power profile and pebble size in a radially cooled pebble bed reactor can be optimized to achieve lower fuel temperatures than current axially cooled designs, while the low pressure drop can be maintained. The radial power profile in the core can be altered by adopting multi-pass fuel management using several radial fuel zones in the core. The optimal power profile yielding a flat temperature profile is derived analytically and is approximated by radial fuel zoning. In this case, the pebbles pass through the outer region of the core first and each consecutive pass is located in a fuel zone closer to the inner reflector. Thereby, the resulting radial distribution of the fissile material in the core is influenced and the temperature profile is close to optimal. The fuel temperature in the pebbles can be further reduced by reducing the standard pebble diameter from 6 cm to a value as low as 1 cm. An analytical investigation is used to demonstrate the effects on the fuel temperature and pressure drop for both radial and axial cooling. Finally, two-dimensional numerical calculations were performed, using codes for neutronics, thermal-hydraulics and fuel depletion analysis, in order to validate the results for the optimized design that were obtained from the analytical investigations. It was found that for a radially cooled design with an optimized power profile and reduced pebble diameter (below 3.5 cm) both a reduction in the pressure drop (Δp = −2.6 bar), which increases the reactor efficiency with several percent, and a reduction in the maximum fuel temperature (ΔT = −50 °C) can be achieved compared to present axially cooled designs.
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Lee, Jae-Young, and Sa-Ya Lee. "Flow Visualization of Pebble Bed HTGR." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58063.
Full textAbstract:
The nuclear core of High Temperature Gas Reactor (HTGR) with pebble bed type has been investigated intensively due to its benefits in management, but its complicated flow geometry requested the reliable analytical method. Recent studies have been made using the three dimensional computational methods but they need to be evaluated with the experimental data. Due to the complicated and narrow flow channel, the intrusive methods of flow measurement are not proper in the study. In the present study, we developed a wind tunnel for the pebble bed geometry in the structure of Face Centered Cubic (FCC) and measure the flow field using the Particle Image Velocimetry (PIV) directly. Due to the limitation of the image harnessing speed and accessibility of the light for particle identification, the system is scaled up to reduce the mean flow velocity by keeping the same Reynolds number of the HTGR. The velocity fields are successfully determined to identify the stagnation points suspected to produce hot spots on the surface of the pebble. It is expected that the present data is useful to evaluate the three dimensional Computational Fluid Dynamics (CFD) analysis. Furthermore, It would provide an insight of experimental method if the present results are compared by those of scaled down and liquid medium.
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Li, Zhifeng, Liangzhi Cao, Hongchun Wu, Chenghui Wan, and Tianliang Hu. "Effects of Applying the Implicit Particle Fuel Model for Pebble-Bed Reactors." In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60382.
Full textAbstract:
In the pebble-bed high temperature gas-cooled reactor, there exist randomly located TRISO coated fuel particles in the pebbles and randomly located pebbles in the core, which is known as the double stochastic heterogeneity. In the previous research, the regular lattice pattern was used to approximately simulate the pebble unit cells because the difficulties in modeling the randomly located TRISO geometric. This work aimed at to quantify the stochastic effect of high-temperature gas cooled pebble-bed reactor unit cells, and in view of the strong ability to carry out the accurate simulation of random media, the implicit particle fuel model of Monte Carlo method is applied to analyze to the difference between regular distribution and random distribution. Infinite multiplication factors of the pebble-bed reactor unite cells were calculated by the implicit particle fuel model and simple cube regular lattice pattern at different TRISO packing factor from 0.5%–50%. The results showed that the simple cube regular lattice pattern underestimates the infinite multiplication factors for most packing fractions, but overrates the infinite multiplication factors when the packing fraction is very low.
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Dominguez-Ontiveros, Elvis E., Carlos Estrada-Perez, and Yassin A. Hassan. "Measurements of Flow Modification by Particle Deposition Inside a Packed Bed Using Time-Resolved PIV." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58330.
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In the Advanced Gas Cooled Pebble Bed Reactors for nuclear power generation, the fuel is spherical coated particles. The energy transfer phenomenon requires detailed understanding of the flow and temperature fields around the spherical fuel pebbles. Detailed information of the complex flow structure within the bed is needed. Generally, for computing the flow through a packed bed reactor or column, the porous media approach is usually used with lumped parameters for hydrodynamic calculations and heat transfer. While this approach can be reasonable for calculating integral flow quantities, it may not provide all the detailed information of the heat transfer and complex flow structure within the bed. The present experimental study presents the full velocity field using particle image velocity technique (PTV) in a conjunction with matched refractive index fluid with the pebbles to achieve optical access. Velocity field measurements are presented delineating the complex flow structure.
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Hiruta, Hikaru, Abderrafi M. Ougouag, Hans D. Gougar, et al. "CYNOD: A Neutronics Code for Pebble Bed Modular Reactor Coupled Transient Analysis." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58255.
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In this paper, a new neutron kinetics solver for cylindrical R-Z geometry, CYNOD, is presented for the simulation of coupled transient problems for pebble bed reactors. The code utilizes the Direct Coarse Mesh Finite Difference method, in which a set of one-dimensional equations in each transverse direction is solved by means of the analytic Green’s function method. A method that deals with control rod cusping problems is also presented. A heterogeneous fuel kernel model is implemented in order to accurately take into account Doppler feedback effects. Numerical results that demonstrate the accuracy of the code are also presented.
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Mulder, Eben, Dawid Serfontein, and Eberhard Teuchert. "Deep Burn Strategy for Pure Reactor-Grade Plutonium in Pebble Bed High Temperature Gas-Cooled Reactors." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58082.
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In this article an advanced fuel cycle for pebble bed reactors is introduced that can safely and efficiently incinerate pure reactor-grade Pu [Pu(LWR)], thereby fulfilling the bulk of the GNEP waste incineration requirements. It is shown below that the very high fissile content of the Pu(LWR)-fuel enables it to convert practically all of the 240Pu to 241Pu and incinerate it. Since the fuel contains no 238U, no fresh 239Pu is produced. The 239Pu is reduced in-situ by 99.5% and the 240Pu by 97.6%. The only significant fissile isotope remaining is 241Pu, however, it will decay with a half life of 14.4 years to the fertile 241Am by β-decay.
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Yu, Xinli, and Suyuan Yu. "The Gasification of Graphite Matrix in Pebble Bed Reactors." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75827.
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This paper mainly deals with the simulations of graphite matrix of the spherical fuel elements by steam in normal operating conditions. The fuel element matrix graphite was firstly simplified to an annular part in the simulations. Then the corrosions to the matrix graphite in 10 MW High Temperature Gas-cooled Reactor (HTR-10) and the High Temperature Gas-cooled Reactor—–Pebble-bed Module (HTR-PM) were investigated respectively. The results showed that the gasification of fuel element matrix graphite was uniform and mainly occurred at the bottom of the core in both of the reactors in the mean residence time of the spherical fuel elements. This was mainly caused by the designed high temperature at the bottom. The total mass gasified in HTR-PM was much greater than the HTR-10, while it did not mean much severer corrosion occurred there. As it is known the core volume of HTR-PM is much larger than the HTR-10, which will result in much greater consumed graphite even for the same corrosion rate. The steam only lost about 1 to 3 percent after flowing through the cores in both reactors for different steam conditions. The corrosion of graphite became worse when the steam concentrations increased in helium coolant. The results also indicated that the corrosion rate of fuel element matrix graphite tended to increase slightly with the prolonging of the service time.
Reports on the topic "Pebble bed reactors – Temperature"
1
Zou, Ling, Dan O'Grady, Guojun Hu, and Rui Hu. Explicit Modeling of Pebble Temperature in the Porous-medium Framework for Pebble-bed Reactors Applications. Office of Scientific and Technical Information (OSTI), 2021. http://dx.doi.org/10.2172/1773605.
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H. D. Gougar and C. B. Davis. Reactor Pressure Vessel Temperature Analysis for Prismatic and Pebble-Bed VHTR Designs. Office of Scientific and Technical Information (OSTI), 2006. http://dx.doi.org/10.2172/911272.
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B. Boer and A. M. Ougouag. Very High Temperature Reactor (VHTR) Deep Burn Core and Fuel Analysis -- Complete Design Selection for the Pebble Bed Reactor. Office of Scientific and Technical Information (OSTI), 2010. http://dx.doi.org/10.2172/991896.
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Kovacic, Donald N., Philip Gibbs, and Logan Scott. Model MC&A for Pebble Bed Reactors. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1606926.
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Cui, Yonggang. Machine Learning in Safeguards at Pebble Bed Reactors. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1679954.
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Ugaz, Victor, Yassin Hassan, Thien Nguyen, and Elia Merzari. Experimental and Computational Analysis of NEAMS Pebble Bed Reactors. Office of Scientific and Technical Information (OSTI), 2019. http://dx.doi.org/10.2172/1580655.
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Hans D. Gougar, Abderrafi M. Ougouag, and William K. Terry. Advanced Core Design And Fuel Management For Pebble-Bed Reactors. Office of Scientific and Technical Information (OSTI), 2004. http://dx.doi.org/10.2172/911213.
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Sen, Sonat. Benchmark for Fuel Shuffling and Depletion for Pebble Bed Reactors. Office of Scientific and Technical Information (OSTI), 2020. http://dx.doi.org/10.2172/1708878.
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Forsberg, Charles W., and David Lewis Moses. Safeguards Challenges for Pebble-Bed Reactors (PBRs):Peoples Republic of China (PRC). Office of Scientific and Technical Information (OSTI), 2009. http://dx.doi.org/10.2172/969660.
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Mui, Travis, Ishak Johnson, Ling Zou, and Rui Hu. Improvements of SAM Heat Transfer Models for Molten Salt-Cooled Pebble Bed Reactors. Office of Scientific and Technical Information (OSTI), 2021. http://dx.doi.org/10.2172/1808874.
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