SiC encapsulation of (V)HTR components and waste by laser beam joining of ceramics

Knorr, J.; Lippmann, Wolfgang; Reinecke, Andrea; Wolf, Robert; Kerber, A.; Wolter, Alexander

doi:10.1016/j.nucengdes.2008.01.022

Cited by 13 publications

(3 citation statements)

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“…Also encapsulation of spherical fuel elementsmoulded and pressed like standard elements -in SiC half spheres has been considered. With the laser beam joining of ceramics the key technology is now available for the SiC encapsulation of (V)HTR components and waste [6]. The irradiation behavior of the solder is under investigation.…”

Section: Corrosion-resistance Coating Methodsmentioning

confidence: 99%

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Upgrading (V)HTR fuel elements for generationIV goals by SiC encapsulation

Knorr¹,

Kerber²,

Moormann

2012

Kerntechnik

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The pebble bed reactor is one of the most promising concepts for (V)HTR. Nevertheless recent re-evaluation of AVR and THTR results emphasizes once more that claimed advantages strongly depend on the properties of the fuel elements and their behavior under operational conditions. Additionally safeguards, waste management and disposal aspects gain increasing importance today. The conventional uncoated graphite pebbles meet only inadequately the requirements of Generation IV facilities. Since long experts agree, that corrosionresistant pebbles with high retention capability for fission products would considerably improve the chances of the pebble bed reactor concept. With laser beam joining of ceramics the key technology is now available for the silicon carbide (SiC) encapsulation of (V)HTR components. The envisaged innovative fuel element consists of a robust SiC hollow sphere filled with moderator and TRISO coated particles. The positive assessment according to Gen IV criteria should justify necessary R&D efforts to obtain qualified fuel elements and demonstrate their superiority under operational conditions. Verbesserung der (V)HTR Brennelemente gemäß Generation IV-Zielen durch SiC-Einkapselung. Der Kugelhaufenreaktor ist eines der vielversprechendsten Konzepte für den (V)HTR. Nichtsdestotrotz zeigen neuere Einschätzungen der AVR-und THTR-Ergebnisse einmal mehr, dass die reklamierten Vorteile stark von den Eigenschaften der Brennelemente und ihrem Verhalten unter Betriebsbedingungen abhängen. Zusätzlich gewinnen heute Aspekte von Safeguards, Abfall-Management und Endlagerung eine wachsende Bedeutung. Die konventionellen, unbeschichteten Graphit-Kugeln erfüllen die Anforderungen an Generation IV-Anlagen nur ungenügend. Seit langen ist man sich in Fachkreisen einig, dass korrosionsresistente Brennelemente mit hoher Rückhal-tefähigkeit für Spaltprodukte die Zukunftschancen des Kugelhaufenreaktor-Konzepts erheblich verbessern würden. Mit dem Laser-Fügeverfahren für Keramik ist nun die Schlüssel-technologie für eine Siliziumkarbid (SiC)-Kapselung von (V)HTR-Komponenten verfügbar. Das vorgestellte innovative Brennelement soll aus einer robusten SiC-Hohlkugel bestehen, die mit dem Moderatormaterial und TRISO Coated Particles gefüllt wird. Die positive Einschätzung der erwarteten Eigenschaften gemäß den Gen IV-Kriterien sollte verstärkte F&E-Anstrengungen rechtfertigen, um qualifizierte Brennelemente herzustellen und ihre Überlegenheit unter Betriebsbedingungen nachzuweisen.

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Section: Corrosion-resistance Coating Methodsmentioning

confidence: 99%

“…After filling the moderator-fuel matrix in the SiC hollow sphere and densification by vibrating technology the opening is closed with a SiC plug and gas-tight sealing through laser beam joining [6]. Recent R&D efforts were focussed on two issues:…”

Section: Sic Hollow Sphere Encapsulationmentioning

confidence: 99%

Upgrading (V)HTR fuel elements for generationIV goals by SiC encapsulation

Knorr¹,

Kerber²,

Moormann

2012

Kerntechnik

Self Cite

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“…More specifically, SiC is being considered for nuclear applications due to its low neutron absorption cross section, stability under high-temperature neutron irradiation at elevated temperatures, and inherently low level of long-lived radioisotopes produced through nuclear transmutations [1,3,[4][5][6][7]. These properties make it a suitable material for structural and cladding components of fission reactors [8]; blanket components of fusion reactors [4,5,9]; encapsulation media for storing radioactive waste [10]; and components of Tri-Structural Isotropic (TRISO) and other fuel-pellet designs for advanced fission reactor concepts [11]. SiC is also a wide band-gap semiconductor that retains its semiconducting properties to high temperatures, making it useful for devices operating at high power and high frequency, and in high temperature environments (though, unfortunately, dopable only by ion implantation [12]).…”

Section: Introductionmentioning

confidence: 99%

The role of chemical disorder and structural freedom in radiation-induced amorphization of silicon carbide deduced from electron spectroscopy and ab initio simulations

Leide

Hobbs

Wang

et al. 2019

Journal of Nuclear Materials

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Chemical disorder has previously been proposed as an explanation for the anomalously facile amorphization of silicon carbide (SiC), on the basis of topological connectivity arguments alone. In this exploratory study, "amorphous" (formally, aperiodic) SiC structures produced in ab initio molecular dynamics simulations were assessed for their connectivity topology and used to compute synthetic electron energyloss spectra (EELS) using the ab initio real-space multiple scattering code FEFF. The synthesized spectra were compared to experimental EELS spectra collected from an ionamorphized SiC specimen. A threshold level of chemical disorder χ (expressed as the ratio of the number of carbon-carbon bonds to the number of carbon-silicon bonds) was found to be χ ≈ 0.38, above which structural relaxation resulted in formally aperiodic structures. Different disordering methodologies resulted in identifiably different aperiodic structures, as assessed by local-cluster analysis and confirmed by collecting near-edge electron energy-loss spectra (ELNES). Such structural differences are predicted to arise for SiC crystals amorphized by irradiations involving different damage mechanismsand therefore differing disordering mechanisms-for example, when contrasting the respective amorphized products of ion irradiation, neutron irradiation, and high-energy electron irradiation. Evidence for sp 2-hybridized carbon bonding is observed, both experimentally in the irradiated sample and in simulations, and related to connectivity topology-based models for the amorphization of silicon carbide. New information about the probable intermediate-range structures present in amorphized silicon carbide is deduced from enumeration of primitive rings and evolution of local cluster configurations during the ab initio-modelled amorphization sequences.

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SiCf/SiC composites as core materials for Generation IV nuclear reactors

Park

2017

Structural Materials for Generation IV Nuclear Reactors

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SiC encapsulation of (V)HTR components and waste by laser beam joining of ceramics

Cited by 13 publications

References 1 publication

Upgrading (V)HTR fuel elements for generationIV goals by SiC encapsulation

Upgrading (V)HTR fuel elements for generationIV goals by SiC encapsulation

The role of chemical disorder and structural freedom in radiation-induced amorphization of silicon carbide deduced from electron spectroscopy and ab initio simulations

SiCf/SiC composites as core materials for Generation IV nuclear reactors

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