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Title: Measurement of PuO2 film thickness by electron probe microanalysis (EPMA) calibration curve method

Abstract

Plutonium (Pu) surfaces are highly reactive toward oxygen containing species and, therefore, invariably covered with oxides (e.g. PuO2) during transport and handling. The actual thickness of the surface oxide may dictate if a plutonium part is suitable for a certain application. As a result, a cost-effective, quick, non-destructive, yet reliable means to measure the oxide layer thickness formed on Pu samples is desirable. In this study, the cross-sections of a series of room temperature grown oxides on Pu samples were trenched by focus ion beam (FIB) then observed by scanning electron microscopy (SEM) to measure the surface oxide thicknesses, which were then combined with the corresponding oxygen k-ratios provided by electron probe microanalysis (EPMA) to form calibration curves. Oxide thickness measurements for the calibration curves were made on samples within the typical SEM observable range for PuO2 (35–400 nm). The portion of the calibration curve in the thinner oxide region (<35 nm) were approximated via Pouchou and Pichoir’s Φ(ρz) theory. Two specimens with micrometer-thick PuO2 standards (one formed at room temperature and the other at higher temperature with a higher level of crystallinity) were made for the k-ratios in this study, allowing EPMA users to choose the standard that bestmore » suits their needs. If the surface corrosion is known to be PuO2 (from the environment in which the Pu sample is stored) or if the stoichiometry of the surface oxide is confirmed by a preliminary/compliment technique, these calibration curves allow EPMA users to quickly and efficiently determine PuO2 thicknesses from the measured oxygen k-ratios of their samples. The methodology presented in this study can also be used as a template for creating calibration curves for oxides grown on other actinides.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [1]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1597211
Alternate Identifier(s):
OSTI ID: 1581010
Report Number(s):
LLNL-JRNL-791483
Journal ID: ISSN 0022-3115; 990598
Grant/Contract Number:  
AC52-07NA27344
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 530; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Stanford, J. A., Teslich, N., Donald, S., Saw, C. K., Gollott, R., and Dinh, L. N. Measurement of PuO2 film thickness by electron probe microanalysis (EPMA) calibration curve method. United States: N. p., 2019. Web. https://doi.org/10.1016/j.jnucmat.2019.151968.
Stanford, J. A., Teslich, N., Donald, S., Saw, C. K., Gollott, R., & Dinh, L. N. Measurement of PuO2 film thickness by electron probe microanalysis (EPMA) calibration curve method. United States. https://doi.org/10.1016/j.jnucmat.2019.151968
Stanford, J. A., Teslich, N., Donald, S., Saw, C. K., Gollott, R., and Dinh, L. N. Sat . "Measurement of PuO2 film thickness by electron probe microanalysis (EPMA) calibration curve method". United States. https://doi.org/10.1016/j.jnucmat.2019.151968. https://www.osti.gov/servlets/purl/1597211.
@article{osti_1597211,
title = {Measurement of PuO2 film thickness by electron probe microanalysis (EPMA) calibration curve method},
author = {Stanford, J. A. and Teslich, N. and Donald, S. and Saw, C. K. and Gollott, R. and Dinh, L. N.},
abstractNote = {Plutonium (Pu) surfaces are highly reactive toward oxygen containing species and, therefore, invariably covered with oxides (e.g. PuO2) during transport and handling. The actual thickness of the surface oxide may dictate if a plutonium part is suitable for a certain application. As a result, a cost-effective, quick, non-destructive, yet reliable means to measure the oxide layer thickness formed on Pu samples is desirable. In this study, the cross-sections of a series of room temperature grown oxides on Pu samples were trenched by focus ion beam (FIB) then observed by scanning electron microscopy (SEM) to measure the surface oxide thicknesses, which were then combined with the corresponding oxygen k-ratios provided by electron probe microanalysis (EPMA) to form calibration curves. Oxide thickness measurements for the calibration curves were made on samples within the typical SEM observable range for PuO2 (35–400 nm). The portion of the calibration curve in the thinner oxide region (<35 nm) were approximated via Pouchou and Pichoir’s Φ(ρz) theory. Two specimens with micrometer-thick PuO2 standards (one formed at room temperature and the other at higher temperature with a higher level of crystallinity) were made for the k-ratios in this study, allowing EPMA users to choose the standard that best suits their needs. If the surface corrosion is known to be PuO2 (from the environment in which the Pu sample is stored) or if the stoichiometry of the surface oxide is confirmed by a preliminary/compliment technique, these calibration curves allow EPMA users to quickly and efficiently determine PuO2 thicknesses from the measured oxygen k-ratios of their samples. The methodology presented in this study can also be used as a template for creating calibration curves for oxides grown on other actinides.},
doi = {10.1016/j.jnucmat.2019.151968},
journal = {Journal of Nuclear Materials},
number = C,
volume = 530,
place = {United States},
year = {2019},
month = {12}
}

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