Lattice parameter and dimensional changes in graphite irradiated between 300 and 1350°C

Abstract

The changes in lattice parameters and dimensions of graphite irradiated in the range 300–650°C up to a dose of 5 × 10 21 n.cm −2 have been attributed to four types of radiation defect. These are vacant lattice sites, interstitial loops, vacancy lines and vacancy loops. Evidence for the occurrence of these defects is discussed and their concentrations are determined from the experimental data. The values obtained are used to check theories of the nucleation and growth of interstitial loops and vacancy lines. Graphite has also been irradiated to high doses in this temperature range in the Dounreay Fast Reactor and at higher temperatures to somewhat lower doses in the reactor PLUTO at Harwell. Quantitative analysis is not possible under these conditions but qualitative interpretations of the behaviour are put forward.