A revised description of graphite irradiation induced creep

The UK fleet of advanced gas-cooled reactors (AGR) have been operating for a substantial period of time and rely on data obtained from material test reactor (MTR) programs, dating back to the 1960s and through to the end of the 1980s, to support current and future operation. Historically an empirical approach to the irradiation behaviour of graphite has been used and, due to the nature of the available MTR data and the lack of a consistent set of data containing all the relevant measurements, this is still largely the case at present. Differences in interpretation of the available MTR data can have a significant impact on the assessed integrity of core components. Consequently, a thorough review of the basis of the current models is being carried out, and new models are being developed as necessary. This paper presents some new interpretations of the available low fluence MTR data for irradiation creep and application of a revised model to some high fluence MTR data.