Influence of 2D and 3D convection–diffusion flow on tritium permeation in helium cooled solid breeder blanket units

Guo, Wenfeng; Ying, Alice; Ni, Ming-Jiu; Abdou, Mohamed

doi:10.1016/j.fusengdes.2005.08.059

Cited by 11 publications

(5 citation statements)

References 5 publications

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“…T urbulent Rayleigh-Bénard convection (RBC), triggered in a fluid layer which is uniformly heated from below and cooled from above, is considered the paradigm for buoyancy-driven turbulence reaching from stellar convection (1) via atmospheric (2) and oceanic (3) turbulence to cooling blankets in nuclear engineering (4) or the storage of renewable energy in liquid metal batteries (5). A central question in RBC is the fundamental law governing the global turbulent transport of heat and momentum across the convection layer as a function of dimensionless parameters characterizing the flow (6)(7)(8)(9)(10)(11).…”

Section: The Global Transport Of Heat and Momentum In Turbulent Convementioning

confidence: 99%

Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵

Iyer

Scheel

Schumacher

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The global transport of heat and momentum in turbulent convection is constrained by thin thermal and viscous boundary layers at the heated and cooled boundaries of the system. This bottleneck is thought to be lifted once the boundary layers themselves become fully turbulent at very high values of the Rayleigh numberRa—the dimensionless parameter that describes the vigor of convective turbulence. Laboratory experiments in cylindrical cells forRa≳1012have reported different outcomes on the putative heat transport law. Here we show, by direct numerical simulations of three-dimensional turbulent Rayleigh–Bénard convection flows in a slender cylindrical cell of aspect ratio1/10, that the Nusselt number—the dimensionless measure of heat transport—follows the classical power law ofNu=(0.0525±0.006)×Ra0.331±0.002up toRa=1015. Intermittent fluctuations in the wall stress, a blueprint of turbulence in the vicinity of the boundaries, manifest at allRaconsidered here, increasing with increasingRa, and suggest that an abrupt transition of the boundary layer to turbulence does not take place.

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Section: The Global Transport Of Heat and Momentum In Turbulent Convementioning

confidence: 99%

Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵

Iyer

Scheel

Schumacher

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…However, analysis shows no apparent benefit on tritium permeation reduction due to the wall jet velocity profile until the average purge gas velocity reaches about 10 cm/s [91]. Tritium permeation at the low purge gas velocity is still a concern although the isotope swamping effect may help lessen this problem.…”

Section: Tritium Release Inventory and Control (Solid Breeder)mentioning

confidence: 99%

Blanket/first wall challenges and required R&D on the pathway to DEMO

Abdou

Morley

Smolentsev

et al. 2015

Fusion Engineering and Design

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a b s t r a c tThe breeding blanket with integrated first wall (FW) is the key nuclear component for power extraction, tritium fuel sustainability, and radiation shielding in fusion reactors. The ITER device will address plasma burn physics and plasma support technology, but it does not have a breeding blanket. Current activities to develop "roadmaps" for realizing fusion power recognize the blanket/FW as one of the principal remaining challenges. Therefore, a central element of the current planning activities is focused on the question: what are the research and major facilities required to develop the blanket/FW to a level which enables the design, construction and successful operation of a fusion DEMO? The principal challenges in the development of the blanket/FW are: (1) the Fusion Nuclear Environment -a multiple-field environment (neutrons, heat/particle fluxes, magnetic field, etc.) with high magnitudes and steep gradients and transients; (2) Nuclear Heating in a large volume with sharp gradients -the nuclear heating drives most blanket phenomena, but accurate simulation of this nuclear heating can be done only in a DT-plasma based facility; and (3) Complex Configuration with blanket/first wall/divertor inside the vacuum vessel -the consequence is low fault tolerance and long repair/replacement time.These blanket/FW development challenges result in critical consequences: (a) non-fusion facilities (laboratory experiments) need to be substantial to simulate multiple fields/multiple effects and must be accompanied by extensive modeling; (b) results from non-fusion facilities will be limited and will not fully resolve key technical issues. A DT-plasma based fusion nuclear science facility (FNSF) is required to perform "multiple effects" and "integrated" experiments in the fusion nuclear environment; and (c) the Reliability/Availability/Maintainability/Inspectability (RAMI) of fusion nuclear components is a major challenge and is one of the primary reasons why the blanket/FW will pace fusion development toward a DEMO.This paper summarizes the top technical issues and elucidates the primary challenges in developing the blanket/first wall and identifies the key R&D needs in non-fusion and fusion facilities on the path to DEMO.Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

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“…A diverse set of systems have been modeled as porous media, ranging from the flow of subterranean water through permeable rock to conductive heat flow through composite materials [8]. Within the nuclear engineering field, porous media models are commonly applied to flow and heat transfer in tube-in-shell heat exchangers [9], quenched corium heaps [10,11], tritium breeder blankets in fusion reactors [12][13][14], and pin-fueled fission reactors [15]. For application to PBRs, the solid matrix is interpreted as the stacked reflector blocks and randomly heaped pebbles, while the interconnected voids correspond to the interstices between pebbles and blocks and the machined flow channels within blocks.…”

Section: Physical Modelsmentioning

confidence: 99%

“…Any tensor can be written as the sum of symmetric and antisymmetric parts. Applying this to the velocity gradient tensor gives 14) where the symmetric and antisymmetric components are defined as e i j ≡ 1 2 16) Within the applicability of a one-term Taylor series, setting e i j = 0 for all i and j to isolate the effect of ξ shows that ξ represents rigid rotation of the fluid particle. To determine the angular velocity characterizing this rigid rotation, Eq.…”

Section: The Momentum Equationmentioning

confidence: 99%

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Pronghorn Theory Manual

Novak

Schunert

Carlsen

et al. 2020

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Influence of 2D and 3D convection–diffusion flow on tritium permeation in helium cooled solid breeder blanket units

Cited by 11 publications

References 5 publications

Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵

Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵

Blanket/first wall challenges and required R&D on the pathway to DEMO

Pronghorn Theory Manual

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Influence of 2D and 3D convection–diffusion flow on tritium permeation in helium cooled solid breeder blanket units

Cited by 11 publications

References 5 publications

Classical 1/3 scaling of convection holds up to Ra = 10 15

Classical 1/3 scaling of convection holds up to Ra = 10 15

Blanket/first wall challenges and required R&D on the pathway to DEMO

Pronghorn Theory Manual

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Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵

Classical 1/3 scaling of convection holds up to Ra = 10 ¹⁵