Studies of irradiation creep on core graphite by thermal annealing

The mechanism of irradiation creep and its effect on the internal stresses of reactor core graphite components are not well understood. Historical studies on Materials Test Reactor creep specimens have shown that thermal annealing can lead to recovery of creep strain. By selecting appropriate sets o...

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Bibliographic Details
Published in:Journal of nuclear materials 2020-10, Vol.539, p.152309, Article 152309
Main Authors: Tzelepi, A., Dinsdale-Potter, J., Wilkinson, S., Shaw, T.L., Davies, B.C., Davies, M.A.
Format: Article
Language:English
Subjects:
Annealing
Creep (materials)
CTE
Dimensional change
Graphite
Inspection
Irradiation
Irradiation creep
Materials testing
Mechanical properties
Modulus of elasticity
Radioactivity
Raman
Raman spectroscopy
Reactors
Residual stress
Thermal expansion
Young’s modulus
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Summary:The mechanism of irradiation creep and its effect on the internal stresses of reactor core graphite components are not well understood. Historical studies on Materials Test Reactor creep specimens have shown that thermal annealing can lead to recovery of creep strain. By selecting appropriate sets of trepanned graphite specimens for the AGR cores, the thermal annealing programme in this work uses the findings of these historical studies in order to investigate irradiation creep and importantly, the stress state of AGR core bricks. Changes in dimensions, Coefficient of Thermal Expansion and Young’s modulus after each annealing step are reported. Laser Raman spectroscopy is used to investigate the effect of thermal annealing on irradiated graphite. The results are combined with core inspection data and demonstrate the complexity of estimating irradiation creep in different parts of reactor graphite components. •Innovative approach to assess the stress state of graphite core components.•Comparison with core inspection data.•Unlike Materials Test Reactor specimens, reactor specimens experience a multiaxial stress state.•First Laser Raman study into the effects of thermal annealing on irradiated graphite.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2020.152309