Analysis of fuel element matrix graphite corrosion in HTR-PM for normal operating conditions

Yu, Xinli; Yu, Suyuan

doi:10.1016/j.nucengdes.2009.12.015

Cited by 35 publications

(19 citation statements)

References 14 publications

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“…It is expected that graphite chronic oxidation during normal operation will be caused in principal by the presence of water traces in helium. The partial pressures of gas impurities in the He coolant corresponding to several HTGR designs are shown in Table 1 [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Oxidation of PCEA nuclear graphite by low water concentrations in helium

Contescu¹,

Mee²,

Wang³

et al. 2014

Journal of Nuclear Materials

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a b s t r a c tAccelerated 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.

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Section: Introductionmentioning

confidence: 99%

Oxidation of PCEA nuclear graphite by low water concentrations in helium

Contescu¹,

Mee²,

Wang³

et al. 2014

Journal of Nuclear Materials

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“…Oxidation of SiC by steam according reactions (6) and (7) above forms a SiO 2 layer. In presence of H 2 O, however, this layer no longer protects the underlying SiC fiber and gasification continues according to reactions (8) and (9) above, controlled by the diffusion of volatile species Si-O x -H y(g) through a porous boundary layer.…”

Section: Effect Of Watermentioning

confidence: 99%

Initial assessment of environmental effects on SiC/SiC composites in helium-cooled nuclear systems

Contescu¹

2013

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“…The demonstration power plant and the pebble-bed modular HTR (HTR-PM) are graphite-moderated, heliumcooled and shall operate at a nominal thermal power of 250 MW. The helium flow at outlet of the hot gas duct is about 750°C, pressured at about 7.0 MPa [1][2][3]. The power system of HTR-PM essentially consists of a reactor, a primary loop and a secondary loop.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigations of thermal mixing performance of a hot gas mixing structure in high-temperature gas-cooled reactor

et al. 2016

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A numerical simulation study was performed to clarify the thermal mixing characteristics of coolant in the core bottom structure of the high-temperature gas-cooled reactor (HTR). The flow field and temperature field in the hot gas chamber and the hot gas duct of the HTR were obtained based on the commercial computational fluid dynamics (CFD) program. The numerical simulation results showed that the helium flow with different temperatures in the hot gas mixing chamber and the hot gas duct mixed intensively, and the mixing rate of the temperature in the outlet of the hot gas duct reached 98 %. The results indicated many large-scale swirling flow structures and strong turbulence in the hot gas mixing chamber and the entrance of the hot gas duct, which were responsible for the excellent thermal mixing of the hot gas chamber and the hot gas duct. The calculated results showed that the temperature mixing rate of the hot gas chamber decreased only marginally with increasing Reynolds number.

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Analysis of fuel element matrix graphite corrosion in HTR-PM for normal operating conditions

Cited by 35 publications

References 14 publications

Oxidation of PCEA nuclear graphite by low water concentrations in helium

Oxidation of PCEA nuclear graphite by low water concentrations in helium

Initial assessment of environmental effects on SiC/SiC composites in helium-cooled nuclear systems

Numerical investigations of thermal mixing performance of a hot gas mixing structure in high-temperature gas-cooled reactor

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