Characterisation of deuterium distributions in corroded zirconium alloys using high-resolution SIMS imaging

Liu, Junliang; Li, Kexue; Sayers, James; Aarholt, Thomas; He, Guanze; Hulme, Helen; Garner, Alistair; Preuss, Michael; Nordin, Heidi; Partezana, Joanna M; Limbäck, Magnus; Lozano-Pérez, Sergio; Ortner, Susan; Grovenor, C.R.M.

doi:10.1016/j.actamat.2020.09.040

Cited by 22 publications

(11 citation statements)

References 64 publications

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“…Recent work by Li et al 34 and Liu et al 57 used NanoSIMS to investigate the distribution of 2 H in zirconium oxides 34 , 57 but did not observe the same trapping behaviour as seen here. This is due to the effect of the NanoSIMS analysis itself on the trapping sites, as beam damage and mixing from the 16 keV Cs + ion beam destroys the trapping sites below the sampling depth of the NanoSIMS, allowing 2 H to escape before being detected.…”

Section: Discussionsupporting

confidence: 40%

Evidence of hydrogen trapping at second phase particles in zirconium alloys

Jones

Tuli

Shah

et al. 2021

Sci Rep

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Zirconium alloys are used in safety–critical roles in the nuclear industry and their degradation due to ingress of hydrogen in service is a concern. In this work experimental evidence, supported by density functional theory modelling, shows that the α-Zr matrix surrounding second phase particles acts as a trapping site for hydrogen, which has not been previously reported in zirconium. This is unaccounted for in current models of hydrogen behaviour in Zr alloys and as such could impact development of these models. Zircaloy-2 and Zircaloy-4 samples were corroded at 350 °C in simulated pressurised water reactor coolant before being isotopically spiked with 2H2O in a second autoclave step. The distribution of 2H, Fe and Cr was characterised using nanoscale secondary ion mass spectrometry (NanoSIMS) and high-resolution energy dispersive X-ray spectroscopy. 2H− was found to be concentrated around second phase particles in the α-Zr lattice with peak hydrogen isotope ratios of 2H/1H = 0.018–0.082. DFT modelling confirms that the hydrogen thermodynamically favours sitting in the surrounding zirconium matrix rather than within the second phase particles. Knowledge of this trapping mechanism will inform the development of current understanding of zirconium alloy degradation through-life.

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Section: Discussionsupporting

confidence: 40%

Evidence of hydrogen trapping at second phase particles in zirconium alloys

Jones

Tuli

Shah

et al. 2021

Sci Rep

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“…For example the study of hydrogen or deuterium diffusion through oxides on Zr alloys, 11,7,12,13 the incorporation of cations like Li Na and K into zirconium oxide 14 and the study of second phase particles (SPPs) 15–17 . Recently, we have shown that high‐resolution SIMS analysis of oxidised zirconium alloys using a CAMECA NanoSIMS 50 instrument enables the 3D characterisation of deuterium distributions 9,18 …”

Section: Introductionmentioning

confidence: 99%

“…Zirconium alloys have been used as the fuel cladding in many types of nuclear reactors for many years, and hydrogen pickup (HPU) is one of the major degradation mechanisms limiting its in‐service lifetime 22 . In our recent work, 9,18 we have used high‐resolution SIMS analysis to reveal the 3‐dimensional (3D) distribution of deuterium in oxides formed on Zr alloys in autoclaves, and proposed that interconnected nano‐pores in the oxide layers can serve as the preferential transportation pathways for hydrogen from the external cathode to the underlying metal. Because of the limited availability of SIMS instruments that can be used to study highly active samples, only few attempts have been made to carry out similar characterisation of the distribution of hydrogenic species in oxides formed under in‐pile conditions, 7,23,13 and more data is needed to develop more robust mechanisms for in‐reactor HPU.…”

Section: Introductionmentioning

confidence: 99%

“…By applying this methodology to a small piece of bulk fuel cladding material (3 mm × 3 mm × 1 mm) with a rather modest measured activity of ∼1.8 × 10 4 Bq, we estimate the activity of the final specimen is reduced to an unmeasurable value < 6.5 × 10 −3 Bq in the FIB lift‐out sample, and this can then be analysed in a nonnuclear instrument. This methodology has been used to prepare radioactive samples for SIMS analysis in our recent work, 18 in which we have measured the deuterium diffusion coefficients in zirconium oxides formed in‐reactor, and provided direct evidence showing that irradiation can increase the rate of key mechanisms controlling transport of deuterium through the oxide layers on Zr alloys. More results comparing hydrogen and deuterium analysis in Zr alloys from bulk and FIB lift‐out samples can be found in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…More results comparing hydrogen and deuterium analysis in Zr alloys from bulk and FIB lift‐out samples can be found in Refs. (9) and (18).…”

Section: Introductionmentioning

confidence: 99%

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Site‐specific specimen preparation for SIMS analysis of radioactive samples

Liu

Lozano-Pérez

et al. 2020

Journal of Microscopy

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Secondary Ion Mass Spectrometry is an important technique for the study of the composition of a wide range of materials because of the exceptionally high sensitivity that allows the study of trace elements and the ability to distinguish isotopes that can be used as markers for reactions and transport processes. However, when studying nuclear materials, it is often necessary to analyse highly radioactive samples, and only rather few SIMS facilities are available in active environments. In this paper, we present a methodology using focussed ion beam milling to prepare samples from radioactive specimens that are sufficiently large to undertake SIMS mapping experiments over microstructurally significant regions, but with overall activities small enough to be readily transported and analysed by a SIMS instrument in a normal laboratory environment. Radioactive samples prepared using this methodology can also be used for correlative SIMS analysis with other analytical microscopies. SIMS results showing the distributions of deuterium in oxides on in‐reactor corroded zirconium alloys are presented to demonstrate the potential of this sample preparation technique.

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