Oxidation of PCEA nuclear graphite by low water concentrations in helium.
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| Title: | Oxidation of PCEA nuclear graphite by low water concentrations in helium. |
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| Authors: | Contescu, Cristian I.1 ContescuCI@ornl.gov, Mee, Robert W.2, Peng Wang1, Romanova, Anna V.2, Burchell, Timothy D.2 |
| Source: | Journal of Nuclear Materials. Oct2014, Vol. 453 Issue 1-3, p225-232. 8p. |
| Subjects: | Oxidation-reduction reaction kinetics, Water, Helium, Graphite, Acceleration (Mechanics), Metal microstructure, Radioactive substances |
| Abstract: | Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors' knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir-Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800-1100 °C), and partial pressures of water (15-850 Pa) and hydrogen (30-150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Nuclear Materials is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 97648125 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Oxidation of PCEA nuclear graphite by low water concentrations in helium. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Contescu%2C+Cristian+I%2E%22">Contescu, Cristian I.</searchLink><relatesTo>1</relatesTo><i> ContescuCI@ornl.gov</i><br /><searchLink fieldCode="AR" term="%22Mee%2C+Robert+W%2E%22">Mee, Robert W.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Peng+Wang%22">Peng Wang</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Romanova%2C+Anna+V%2E%22">Romanova, Anna V.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Burchell%2C+Timothy+D%2E%22">Burchell, Timothy D.</searchLink><relatesTo>2</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Nuclear+Materials%22">Journal of Nuclear Materials</searchLink>. Oct2014, Vol. 453 Issue 1-3, p225-232. 8p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Oxidation-reduction+reaction+kinetics%22">Oxidation-reduction reaction kinetics</searchLink><br /><searchLink fieldCode="DE" term="%22Water%22">Water</searchLink><br /><searchLink fieldCode="DE" term="%22Helium%22">Helium</searchLink><br /><searchLink fieldCode="DE" term="%22Graphite%22">Graphite</searchLink><br /><searchLink fieldCode="DE" term="%22Acceleration+%28Mechanics%29%22">Acceleration (Mechanics)</searchLink><br /><searchLink fieldCode="DE" term="%22Metal+microstructure%22">Metal microstructure</searchLink><br /><searchLink fieldCode="DE" term="%22Radioactive+substances%22">Radioactive substances</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Accelerated oxidation tests were performed to determine kinetic parameters of the chronic oxidation reaction (i.e. slow, continuous, and persistent) of PCEA graphite in contact with helium coolant containing low moisture concentrations in high temperature gas-cooled reactors. To the authors' knowledge such a study has not been done since the detailed analysis of reaction of H-451 graphite with steam (Velasquez, Hightower, Burnette, 1978). Since that H-451 graphite is now unavailable, it is urgently needed to characterize chronic oxidation behavior of new graphite grades that are being considered for use in gas-cooled reactors. The Langmuir-Hinshelwood mechanism of carbon oxidation by water results in a non-linear reaction rate expression, with at least six different parameters. They were determined in accelerated oxidation experiments that covered a large range of temperatures (800-1100 °C), and partial pressures of water (15-850 Pa) and hydrogen (30-150 Pa) and used graphite specimens thin enough (4 mm) in order to avoid diffusion effects. Data analysis employed a statistical method based on multiple likelihood estimation of parameters and simultaneous fitting of non-linear equations. The results show significant material-specific differences between graphite grades PCEA and H-451 which were attributed to microstructural dissimilarity between the two materials. It is concluded that kinetic data cannot be transferred from one graphite grade to another. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Nuclear Materials is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.jnucmat.2014.07.009 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 8 StartPage: 225 Subjects: – SubjectFull: Oxidation-reduction reaction kinetics Type: general – SubjectFull: Water Type: general – SubjectFull: Helium Type: general – SubjectFull: Graphite Type: general – SubjectFull: Acceleration (Mechanics) Type: general – SubjectFull: Metal microstructure Type: general – SubjectFull: Radioactive substances Type: general Titles: – TitleFull: Oxidation of PCEA nuclear graphite by low water concentrations in helium. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Contescu, Cristian I. – PersonEntity: Name: NameFull: Mee, Robert W. – PersonEntity: Name: NameFull: Peng Wang – PersonEntity: Name: NameFull: Romanova, Anna V. – PersonEntity: Name: NameFull: Burchell, Timothy D. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 10 Text: Oct2014 Type: published Y: 2014 Identifiers: – Type: issn-print Value: 00223115 Numbering: – Type: volume Value: 453 – Type: issue Value: 1-3 Titles: – TitleFull: Journal of Nuclear Materials Type: main |
| ResultId | 1 |
