Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

Zinkle, S.J.; Snead, Lance Lewis

doi:10.1016/0168-583x(96)00016-x

Cited by 190 publications

(70 citation statements)

References 49 publications

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“…Above the critical temperature the SiC remains crystalline although point defects are created by the irradiation resulting in significant strain in the substrate. The critical temperature and critical fluence for amorphization are independent of the crystal polytype [126,131,132]. Wendler at al.…”

Section: Amorphizationmentioning

confidence: 99%

“…At room temperature SiC is easier to amorphize by irradiation than other popular ceramics for the nuclear industry, viz. alumina (Al 2 O 3 ), magnesium aluminate spine1 (MgAl 2 O 4 ), magnesia (MgO), silicon nitride (Si 3 N 4 ) [132]. In both fusion and fission reactors the areas where SiC will be used have temperatures above the critical temperatures reducing many of the negative affects associated with amorphization.…”

Section: Amorphizationmentioning

confidence: 99%

“…The other group are the fission products which leak out off the TRISO particle causing a radiological danger. The most important of these are m 110 Ag, 134 I, 131 Cs and 137 Cs, 90 Sr, 88 Kr and 133 Xe with the following somewhat less important fission products 132 Te, 140 La and the actinide 239 Pu [23,24,25]. In the last section of the paper ( §4) this review will concentrate only on some of the important elements, for the topics of the other sections, specific elements are not really of importance.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion of fission products and radiation damage in SiC

Malherbe

2013

J. Phys. D: Appl. Phys.

109

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A major problem with most of the present nuclear reactors is their safety in terms of the release of radioactivity into the environment during accidents. In some of the future nuclear reactor designs, i.e. Generation IV reactors, the fuel is in the form of coated spherical particles, i.e. TRISO (acronym for Triple Coated Isotropic) particles. The main function of these coating layers is to act as diffusion barriers for radioactive fission products, thereby keeping these fission products within the fuel particles, even under accident conditions. The most important coating layer is composed of polycrystalline 3C-SiC. This paper reviews the diffusion of the important fission products (silver, caesium, iodine and strontium) in SiC. Because radiation damage can induce and enhance diffusion, the paper also briefly reviews damage created by energetic neutrons and ions at elevated temperatures, i.e. the temperatures at which the modern reactors will operate, and the annealing of the damage. The interaction between SiC and some fission products (such as Pd and I) is also briefly discussed. As shown, one of the key advantages of SiC is its radiation hardness at elevated temperatures, i.e. SiC is not amorphized by neutron or bombardment at substrate temperatures above 350°C. Based on the diffusion coefficients of the fission products considered, the review shows that at the normal operating temperatures of these new reactors (i.e. less than 950°C) the SiC coating layer is a good diffusion barrier for these fission products. However, at higher temperatures the design of the coated particles needs to be adapted, possibly by adding a thin layer of ZrC.

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Section: Amorphizationmentioning

confidence: 99%

Section: Amorphizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Diffusion of fission products and radiation damage in SiC

Malherbe

2013

J. Phys. D: Appl. Phys.

109

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“…However, it has been shown both experimentally and theoretically that properties of different SiC polytypes are rather similar in respect of their stability against radiation damage [17]. Therefore, from the point of view of SIMS as an analytical tool, different SiC polytypes would be predicted to behave virtually identically.…”

Section: Sims Analytical Techniquementioning

confidence: 99%

Isotopic heterogeneity in synthetic and natural silicon carbide

Shiryaev

Wiedenbeck

Reutsky

et al. 2008

Journal of Physics and Chemistry of Solids

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The distribution of both carbon and silicon isotopes in synthetic sublimation growth SiC wafers and in natural SiC grains was studied using secondary ion mass-spectrometry (SIMS).Significant variations in both isotopic ratios were observed which were broadly correlated with the crystalline perfection as documented by Raman microspectroscopy. Domains consisting of 15R (or with its admixture) are, on average, enriched in 12 C isotope relative to 6H domains, and they also show larger scatter in their observed silicon isotope ratios. We ascribe such heterogeneity to fluctuations of Si/C ratio in the growth medium and it is possible to model the spatial extent of such fluctuations. For the natural SiC grains the isotopic data suggest that they grew under relatively stable conditions, although some of them show significant isotopic zoning.

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“…The damage in a material caused by radiation can be classed by the type of energy transfer and the resultant implantation volume effects [108,109,97,100,110,99,111,112,113,114,115,116,117]. Gamma radiation, which is not covered here, produces little damage in the materials of interest.…”

Section: Radiation Damagementioning

confidence: 99%

Radiation Damage and Fission Product Release in Zirconium Nitride

Egeland

2005

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Zirconium nitride is a material of interest to the AFCI program due to some of its particular properties, such as its high melting point, strength and thermal conductivity. It is to be used as an inert matrix or diluent with a nuclear fuel based on transuranics. As such, it must sustain not only high temperatures, but also continuous irradiation from fission and decay products. This study addresses the issues of irradiation damage and fission product retention in zirconium nitride through an assessment of defects that are produced, how they react, and how predictions can be made as to the overall lifespan of the complete nuclear fuel package.Ion irradiation experiments are a standard method for producing radiation damage to a surface for observation. Cryogenic irradiations are performed to produce the maximum accumulation of defects, while elevated temperature irradiations may be used to allow defects to migrate and react to form clusters and loops. Cross-sectional transmission electron microscopy and grazing-incidence x-ray diffractometry were used in evaluating the effects that irradiation has on the crystal structure and microstructure of the material. Other techniques were employed to evaluate physical effects, such as nanoindentation and helium release measurements.Results of the irradiations showed that, at cryogenic temperatures, ZrN withstood over 200 displacements per atom without amorphization. No significant change to the lattice or microstructure was observed. At elevated temperatures, the large amount of damage showed mobility, but did not anneal significantly. Defect clustering was possibly observed, yet the size was too small to evaluate, and bubble formation was not observed.Defects, specifically nitrogen vacancies, affect the mechanical behavior of ZrN dramatically. Current and previous work on dislocations shows a distinct change in slip plane, which is evidence of the bonding characteristics. The stacking-fault energy changes dramatically with lowered nitrogen stoichiometry, resulting in widely spaced partial dislocations in ZrN with high nitrogen vacancy concentration.The wide range of nitrogen stoichiometry in the phase field shows that ZrN may accept nitrogen defects readily. Explanations for this are suggested based upon the bonding structure of these cubic nitrides. This structure allows for a solid framework to remain on one sublattice, while at the same time allowing defects on the other sublattice. This allowance for defects allows significant damage from irradiation yet also decreases the drive for cluster growth. This is evidence that the structure will be acceptable for long-term use as a nuclear reactor fuel.

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Influence of irradiation spectrum and implanted ions on the amorphization of ceramics

Cited by 190 publications

References 49 publications

Diffusion of fission products and radiation damage in SiC

Diffusion of fission products and radiation damage in SiC

Isotopic heterogeneity in synthetic and natural silicon carbide

Radiation Damage and Fission Product Release in Zirconium Nitride

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