This paper reports the results of a SIMS analysis of an irradiated High Temperature Reactor (HTR) pebble fuel sample. The pebble, a graphite sphere with a diameter of ~6 cm, contains fissile material in the form of Tristructural ISOtropic (TRISO) coated particles. These particles have an overall diameter of about 1 mm and are composed of fuel kernels (in this case UO₂) coated with successive layers of porous carbon, dense carbon, dense silicon carbide and dense carbon. Up to 10000 coated particles are embedded in the graphite matrix constituting the pebble. The irradiation took place in the High Flux Reactor (HFR) in Petten, Netherlands and achieved a burn-up of 14 % FIMA (fission per initial metal atom). After having tested the potential of the TRISO particles for high temperature performance and very high burn-up, the pebble underwent extended exposure to temperatures up to 1800 °C simulating a loss-of forced cooling accident in the HTR. After the thermal treatment, SIMS was carried out using a Cameca IMS 6f specially shielded and modified for the analysis of irradiated fuels allowing the evaluation of the SiC layer efficiency as a barrier against fission products release.

The distributions of the coated particle main constituents (UO₂, C and Si) as well as of selected isotopes of key fission products (⁸⁵Kr, ⁹⁰Sr, ¹⁰²Ru, ¹⁰⁶Pd, ¹¹⁰Ag, ¹³⁷Cs, ¹⁴²Nd and ¹⁵⁵Eu) were assessed by means of ion mapping at intervals of 75µm using an oxygen primary ion beam. The primary and secondary ion acceleration voltages were +15 and +5 Kv respectively; a beam current of 100 pA was employed.

Nd, a solid fission product, was present exclusively in the UO₂ fuel. Due to its low mobility, Nd is often used as an indicator of local burn-up. A significant number of round metallic precipitates containing Ru and Ag were also identified. Kr was observed in the pores while Cs was hardly found in the fuel matrix, in line with its volatile nature. Fission product release from the fuel kernel towards the outer layers of the particle was evidenced by 1) higher peak count rates for Kr and Cs in the porous carbon area than in the fuel and 2) by decreasing concentration gradients for Sr, Pd, Ag and Eu from the fuel interface towards the outer carbon layers. The dense carbon/SiC interface exhibits high concentrations of Cs and precipitation of other fission products. The fact that most of the elements exhibit a significant count rate decrease between the inner part of the coated particle and the outside confirms the successful containment effect of the SiC layer.

ToF-SIMS analysis of cosmetotextiles

M. Desbrosses⁽¹⁾, J. Azuara⁽¹⁾, A. Bonhomme⁽¹⁾, I. Ferreira⁽²⁾, C. Darroux⁽²⁾, D. Leonard⁽¹⁾

⁽¹⁾ Université de Lyon, UMR CNRS 5280, Institut des Sciences Analytiques, Université Claude Bernard - Lyon, 5 rue de la Doua, 69100 Villeurbanne, France.

⁽²⁾ Institut Français du Textile & de l’Habillement (IFTH) - Avenue Guy de Collongue, 69134 Écully.

Interest in functional textiles for cosmetic applications (cosmetotextiles) has been increasing very rapidly. Among others, anti-odour, hydrating, refreshing, heating effects bring an important added value to textiles. However, this surface functionalization effort triggers the needs for relevant sensitive characterization of these substrates [1]. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) has shown to bring valuable and accurate information on the development of functional textiles (e.g. see [2]).

In this work, a patented original process based on co-precipitation of active agent on the surface was used to obtain cosmetotextiles. ToF-SIMS analysis was used here to identify and localize the active agent and results were compared to those from a complementary quantitative Liquid Chromatography-UV (LC-UV) analysis.

The final aim of the work was to establish the most adapted protocol to reveal efficiency of the surface treatments on textiles. This has been challenging owing to the significant detection of surface finishing (e.g. lubrication applied on the fibers). Using a simple low energy Ar⁺ sputter gun made possible to remove preferentially the finishing layer with a minimum of damage on the surface treated textile [3, 4]. To further optimize this protocol, comparison of depth profiles at different sputtering conditions was proposed for spin-coated and knitted PA66 samples, as well as for untreated and cosmeto-active textiles. Interest for cosmetotextiles development is discussed.

References:

[1] L. Ripoll et al., E-Polymers 10 (2013): 409, doi:10.1515/epoly.2010.10.1.409.

[2] C. Brunon et al., Surface and Interface Analysis 43 (2011): 604–608, doi: 10.1002/sia.3654

[3] J. Brison et al, International Journal of Mass Spectrometry 321–322 (2012): 1–7, doi:10.1016/j.ijms.2012.04.001.

[4] H.-G. Cramer et al., Proceedings of the Sixteenth International Conference on Secondary Ion Mass Spectrometry, SIMS XVI 255 (2008): 966–69, doi:10.1016/j.apsusc.2008.05.028.

As magnetic recording slider is getting smaller and evolves to ultra low flying height, hard drives are more susceptible to failures caused by micro or even nano contamination. The small size and low amount of contaminants present on head and media make materials identification more challenging. In our drive failure analysis, TOF-SIMS is used as a critical surface analysis tool to directly detect contamination source. In this presentation, various successful examples of contamination analysis and data interpretation using multiple analytical tools are discussed, emphasizing the role of TOF-SIMS in failure analysis.