Lifetime evaluation of graphite components for HTGRs

Oku, Tatsuo; Ishihara, Masahiro

doi:10.1016/j.nucengdes.2003.10.001

Cited by 31 publications

(12 citation statements)

References 4 publications

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“…The CTE is observed to initially increase, reaching a maximum, and then decrease and saturate, or possibly pass through a minimum. Similar behavior has been reported for graphite grades N3M [29], ATR-2E [25] and IM1-24 [16]. The CTE behavior at 900°C is described by the equation All CTE data at ~ 600 C Tirr The unirradiated (c = 0) value of the CTE is greater at 900°C (3.9 Â 10 À6°CÀ1 ) than at 600°C (3.5 Â 10 À6°CÀ1 ) as would be expected [17,[30][31][32] due to the thermal closure of Mrozowski cracks in the graphite.…”

Section: Compressive Creepsupporting

confidence: 87%

“…The CTE is observed to initially increase, reaching a maximum, and then decrease. Similar behavior has been reported for graphite grade N3M [29], grade ATR-2E [25] and grade IM1-24 [16]. The irradiated CTE behavior of H-451 at 600°C can be described by the equation…”

Section: Compressive Creepsupporting

confidence: 73%

“…The creep coefficient, k, was found to be independent of the sign of the applied stress, and the linear visco-elastic law was found to be a good fit to low and intermediate dose creep strain data [11,15,16]. However, as increasingly larger creep strain data and neutron dose data became available a marked deviation from the linear law was observed [17,18].…”

Section: Introductionmentioning

confidence: 89%

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Irradiation induced creep behavior of H-451 graphite

Burchell

2008

Journal of Nuclear Materials

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Section: Compressive Creepsupporting

confidence: 87%

Section: Compressive Creepsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 89%

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Irradiation induced creep behavior of H-451 graphite

Burchell

2008

Journal of Nuclear Materials

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“…Generation of new cracks and pores eventually causes total disintegration of the graphite. The lifetime of nuclear graphite is typically defined by the neutron dose at which it returns to its original dimensions [20,21]. Nuclear graphite with a high degree of graphitization has a lower initial number of lattice defect sites available to trap irradiation-induced vacancies, and thus the rate of damage accumulation is reduced [4].…”

Section: High Graphitization Degreementioning

confidence: 99%

Advantages of natural microcrystalline graphite filler over petroleum coke in isotropic graphite preparation

Shen

Huang

et al. 2015

Carbon

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A B S T R A C TGraphite materials are used in high-temperature gas-cooled reactor (HTR) as moderator and reflector. Nuclear graphite is currently manufactured using coke as the filler; however, improvements in the performance of nuclear graphite are anticipated in order to enhance the safety and lifetime of HTRs. Natural microcrystalline graphite (MG), which is a metamorphic product of coal, is an emerging candidate as filler material. This paper proposes the approach of preparing isotropic graphite using MG fillers. The characterization results of MG ores and purified powder indicate a polycrystalline and near-isotropic structure of MG particles. Thus, near-isotropic graphite with an isotropy ratio of 1.10-1.15 can be easily obtained via cold isostatic pressing. The thermal diffusivity of MG-based green body is much higher than that of coke-based one, therefore facilitates the baking step. The advantages of MG-based graphite also include a high degree of graphitization, and a low coefficient of thermal expansion, both of which are highly beneficial to nuclear applications.As a result, MG exhibits a large potential for the application in isotropic nuclear graphite.Ó 2015 Elsevier Ltd. All rights reserved. IntroductionThe moderator in a nuclear reactor thermalizes 2 MeV fast neutrons to 0.025 eV thermal neutrons. With low atomic weight, high moderating ratio and low absorption cross section, H 2 O, D 2 O, Be, and C are four possible moderators [1]. Carbon in the form of graphite offers an acceptable compromise between nuclear properties and cost, therefore graphite is employed as moderator and structural material in high-temperature gas-cooled reactors (HTR) [2,3].

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“…They show creep behavior above 500°C under neutron irradiation as well as irradiation-induced dimensional change. These effects cause stress in the components and are a crucial factor in the component's lifetime [2].…”

Section: Introductionmentioning

confidence: 99%