The role of Pd in the transport of Ag in SiC

Olivier, E.J.; Neethling, J.H.

doi:10.1016/j.jnucmat.2012.07.033

Cited by 38 publications

(37 citation statements)

References 13 publications

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“…However, previous work suggests that some of the intergranular precipitates in the SiC layer of similarly irradiated TRISO fuel may, indeed, be silicides of Pd [13] and/or Pd & U, e.g. Pd x U y Si z [9], while work involving out-of-pile testing indicates the presence of a Pd-Ag-Si solution [7] or Pd 2 Si containing small amounts of Ag (Ag:Pd on the order of 1:30) [6].…”

Section: Resultsmentioning

confidence: 99%

“…The authors of this paper hypothesize that the migration of silver is enabled through Pd-assisted migration, as proposed by [6,7], along grain boundaries with specific crystallographic parameters, essentially adding a grain boundary-dependence on silver migration. This study is expected to provide information to evaluate this theory, as well as other proposed theories of fission product migration, that will be discussed in a future publication.…”

Section: Introductionmentioning

confidence: 95%

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Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel

Lillo

Rooyen

2015

Journal of Nuclear Materials

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Associations of Pd, U and Ag in the SiC layer of neutron-irradiated TRISO fuel

Lillo

Rooyen

2015

Journal of Nuclear Materials

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“…There is a discrepancy between silver diffusion coefficients in the SiC layer in TRISO particles measured in a reactor and in laboratories [25]. One of the explanations for this discrepancy is the influence of reactions between the SiC and other metallic fission products like Pd, which also forms a silicide [26]. Since Zr is also a fission product, the reactions between Zr and SiC have implications for the integrity of the SiC layer in the TRISO particle.…”

Section: Resultsmentioning

confidence: 99%

Kinetics of solid-state reactions between zirconium thin film and silicon carbide at elevated temperatures

Njoroge¹,

Theron²,

Malherbe³

et al. 2014

Nuclear Instruments and Methods in Physics Research Section B:

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Solid state reactions between a thin film (133 nm) of Zr and bulk single crystalline 6H-SiC substrates have been studied at temperatures between 600 °C and 850 °C for durations of 30, 60 and 120 min under high vacuum conditions. The deposited film and reaction zones were investigated by Rutherford backscattering spectrometry (RBS) and X-ray diffraction. The RBS spectra were simulated in order to obtain the deposited layer thickness, reaction zone compositions and reaction zone thickness. The as-deposited spectra fit well with those annealed at 600 °C, thus showing there were no reactions taking place. At temperatures of 700 °C and above, Zr reacted with the SiC substrate and formed a mixed layer of Zr carbide (ZrC x ) and Zr silicides (ZrSi, Zr 2 Si and Zr 5 Si 3 ). Annealing at 850 °C for 240 min revealed that all the deposited Zr had completely reacted. The interface reaction follows the parabolic growth law thereby indicating diffusion controlled reaction kinetics. The activation energy for the diffusion process obtained was 1.6 eV in the relatively narrow temperature range 700-850 °C.

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“…Pd content in the buffer, IPyC and outer pyrolytic carbon (OPyC) was significantly lower than that around the SiC layer indicating a trap or stabilization mechanism in this vicinity. From previous studies [1][2][3] and [8], it is known that Pd forms a silicide when heated in contact with SiC and this lowers the concentration of free Pd in the area and acts as a sink for Pd. Fig.…”

Section: Pd and Ag In Triso Particlesmentioning

confidence: 99%

“…Recently, a number of articles concluded that Ag transport through intact TRISO coatings is related to the presence of Pd [1][2][3][4]. Apart from results from the AGR-1 experiment [5][6][7], studies of Ag release through TRISO particles mostly focussed on out of reactor simulations using bulk-or epitaxial SiC wafers.…”

Section: Introductionmentioning

confidence: 99%