Fuel research and basic aspects of fuel in-pile performance

The approach adopted in the European Institute for Transuranium Elements to study basic aspects of the in-pile performance of a wide range of nuclear fuels (e.g. oxides, carbides, nitrides etc. for LWRs and LMFBRs) is described. It consists of an 'all in-house activity' of fuel fabrication, careful and very detailed characterization and post-irradiation examination of fuels at different burn-ups and following different irradiation conditions, parallel laboratory studies under 'clean conditions' and supporting theoretical and modelling work. The approach is illustrated with typical examples of results obtained in the past 25 years. Finally, more recent results of basic experiments related to fuel in-pile performance are given. (orig.)