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  • J.Kennedy ANS Global 2019 final

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Towards the decontamination of plutonium contaminated bricks: Creation of a cerium-based simulant contamination system

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Towards the decontamination of plutonium contaminated bricks: Creation of a cerium-based simulant contamination system. / Kennedy, J.; Boxall, C.; Banford, A. et al.
2019. 556-565 Paper presented at ANS Global, Seattle, United States.

Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

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Kennedy, J, Boxall, C, Banford, A, Demmer, R & Parker, A 2019, 'Towards the decontamination of plutonium contaminated bricks: Creation of a cerium-based simulant contamination system', Paper presented at ANS Global, Seattle, United States, 22/09/19 - 26/09/19 pp. 556-565.

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@conference{0696722cc4b447e78e87762803ec6de1,
title = "Towards the decontamination of plutonium contaminated bricks: Creation of a cerium-based simulant contamination system",
abstract = "There is a need for the decontamination of a number of plutonium-contaminated bricks encountered in a legacy BUTEX reprocessing plant on Sellafield site in the UK. Documentary review has indicated that the source of the contamination was a 8 mol dm -3 nitric acid process stream containing 10 mmol dm -3 of Pu in either the (III) or (IV) oxidation state. Here we have sought to emulate the behaviour of Pu(III) by treatment of fired clay brick surfaces with a solution of 10 mmol dm -3 Ce(III) nitrate in 8 mol dm -3 nitric acid. XRD, porosimetry and EDX measurements of the untreated bricks reveal them to be comprised of low porosity silica and aluminosilicate phases with a surface layer of a low-Si content Al-C-N oxide derived from the atmosphere of the kiln in which the bricks were fired. Depth profiling after an initial 6 week acid soak reveals that the acid penetrates <10 mm into the brick. SEM/EDX analysis reveals that acid treatment significantly roughens the brick surface due to dissolution the above described Al-C-N oxide layer. The EDX data also shows that virtually no Ce is retained as tenacious contamination at the brick surface; this may be due to a either a mass action/kinetic effect or taken to indicate that trivalent Ce(III) is less likely to absorb at the crystalline silica/aluminosilicate surface of the brick than its more easily hydrolysable tetravalent equivalent. Preliminary higher-resolution EDX analysis indicates that small quantities of Ce(III) can be detected in pores or cracks on the surface of acid-treated brick samples. This suggests that Ce(III) may be non-tenaciously sequestered into surface defects - and that a simple salt wash may be sufficient to remove it. Based on the above observations, potential decontamination strategies are discussed and future studies outlined. ",
keywords = "Aluminum oxide, Brick, Contamination, Decontamination, Depth profiling, Fuels, Light water reactors, Nitric acid, Nuclear fuel reprocessing, Plutonium compounds, Silica, Surface defects, Acid treatments, Crystalline silica, Fired clay bricks, Higher resolution, Measurements of, Oxidation state, Reprocessing plant, Surface layers, Cerium compounds",
author = "J. Kennedy and C. Boxall and A. Banford and R. Demmer and A. Parker",
year = "2019",
month = sep,
day = "22",
language = "English",
pages = "556--565",
note = "ANS Global ; Conference date: 22-09-2019 Through 26-09-2019",

}

RIS

TY - CONF

T1 - Towards the decontamination of plutonium contaminated bricks

T2 - ANS Global

AU - Kennedy, J.

AU - Boxall, C.

AU - Banford, A.

AU - Demmer, R.

AU - Parker, A.

PY - 2019/9/22

Y1 - 2019/9/22

N2 - There is a need for the decontamination of a number of plutonium-contaminated bricks encountered in a legacy BUTEX reprocessing plant on Sellafield site in the UK. Documentary review has indicated that the source of the contamination was a 8 mol dm -3 nitric acid process stream containing 10 mmol dm -3 of Pu in either the (III) or (IV) oxidation state. Here we have sought to emulate the behaviour of Pu(III) by treatment of fired clay brick surfaces with a solution of 10 mmol dm -3 Ce(III) nitrate in 8 mol dm -3 nitric acid. XRD, porosimetry and EDX measurements of the untreated bricks reveal them to be comprised of low porosity silica and aluminosilicate phases with a surface layer of a low-Si content Al-C-N oxide derived from the atmosphere of the kiln in which the bricks were fired. Depth profiling after an initial 6 week acid soak reveals that the acid penetrates <10 mm into the brick. SEM/EDX analysis reveals that acid treatment significantly roughens the brick surface due to dissolution the above described Al-C-N oxide layer. The EDX data also shows that virtually no Ce is retained as tenacious contamination at the brick surface; this may be due to a either a mass action/kinetic effect or taken to indicate that trivalent Ce(III) is less likely to absorb at the crystalline silica/aluminosilicate surface of the brick than its more easily hydrolysable tetravalent equivalent. Preliminary higher-resolution EDX analysis indicates that small quantities of Ce(III) can be detected in pores or cracks on the surface of acid-treated brick samples. This suggests that Ce(III) may be non-tenaciously sequestered into surface defects - and that a simple salt wash may be sufficient to remove it. Based on the above observations, potential decontamination strategies are discussed and future studies outlined.

AB - There is a need for the decontamination of a number of plutonium-contaminated bricks encountered in a legacy BUTEX reprocessing plant on Sellafield site in the UK. Documentary review has indicated that the source of the contamination was a 8 mol dm -3 nitric acid process stream containing 10 mmol dm -3 of Pu in either the (III) or (IV) oxidation state. Here we have sought to emulate the behaviour of Pu(III) by treatment of fired clay brick surfaces with a solution of 10 mmol dm -3 Ce(III) nitrate in 8 mol dm -3 nitric acid. XRD, porosimetry and EDX measurements of the untreated bricks reveal them to be comprised of low porosity silica and aluminosilicate phases with a surface layer of a low-Si content Al-C-N oxide derived from the atmosphere of the kiln in which the bricks were fired. Depth profiling after an initial 6 week acid soak reveals that the acid penetrates <10 mm into the brick. SEM/EDX analysis reveals that acid treatment significantly roughens the brick surface due to dissolution the above described Al-C-N oxide layer. The EDX data also shows that virtually no Ce is retained as tenacious contamination at the brick surface; this may be due to a either a mass action/kinetic effect or taken to indicate that trivalent Ce(III) is less likely to absorb at the crystalline silica/aluminosilicate surface of the brick than its more easily hydrolysable tetravalent equivalent. Preliminary higher-resolution EDX analysis indicates that small quantities of Ce(III) can be detected in pores or cracks on the surface of acid-treated brick samples. This suggests that Ce(III) may be non-tenaciously sequestered into surface defects - and that a simple salt wash may be sufficient to remove it. Based on the above observations, potential decontamination strategies are discussed and future studies outlined.

KW - Aluminum oxide

KW - Brick

KW - Contamination

KW - Decontamination

KW - Depth profiling

KW - Fuels

KW - Light water reactors

KW - Nitric acid

KW - Nuclear fuel reprocessing

KW - Plutonium compounds

KW - Silica

KW - Surface defects

KW - Acid treatments

KW - Crystalline silica

KW - Fired clay bricks

KW - Higher resolution

KW - Measurements of

KW - Oxidation state

KW - Reprocessing plant

KW - Surface layers

KW - Cerium compounds

M3 - Conference paper

SP - 556

EP - 565

Y2 - 22 September 2019 through 26 September 2019

ER -