Irradiation induced changes of thermal expansion (C.T.E.) of nuclear graphite (in English; German)
The coefficient of linear thermal expansion (C.T.E.) increases at low fluences up to about 30%. At irradiation temperatures below 600 deg C it stays, with increasing fluence, higher than before irradiation. At higher temperatures thermal expansion decreases with increasing fluence up to 80% below the initial value. The C.T.E. increase can be explained by the lack of buffering by closing of microcracks. A decrease is possible when new space for buffering of the crystallite expansion in ''c''-direction is available, owing to void clustering and migration. The decrease of C.T.E. is crystallite size dependent--the smaller the crystallites the greater the fractional decrease. Graphites with high crystallinity (natural flake and needle coke) do not show such decrease. (auth)
- Research Organization:
- Kernforschungsanlage Juelich G.m.b.H. (F.R. Germany)
- NSA Number:
- NSA-29-016365
- OSTI ID:
- 4337982
- Report Number(s):
- GERHTR--61
- Country of Publication:
- Germany
- Language:
- English; German
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