Irradiation creep in graphite—some new considerations and observations

✍ Scribed by B.T. Kelly

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 528 KB
• Volume: 30
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(92)90034-t

✦ Synopsis

Abstmd-Irradiation

creep in reactor graphite is normally taken to be linear visco-elastic in character, but modified by any structural changes in the graphite, such as those due to radiolytic oxidation or dimensional changes. Corrections for these changes are made to the creep rate using the well established correlations of creep rate with the appropriate elastic compliance. Measurements of the changes in thermal-expansion coefficient with creep strain show that small creep strains perturb the graphite structure significantly, and the standard definition of creep strain is not strictly correct. In this situation, corrections to the creep rate by measurements on unstressed control samples become inaccurate with increasing creep strain. New measurements are reported of thermal-expansion coefficient changes due to creep strain, both parallel and perpendicular to the applied stress, using samples from the earlier creeu studies in the BR-2 reactor. The effect of these studies on calculations of reactor-brick internal stre&es is considered.