Thirty years of NAA developments and applications at the THETIS reactor ofthe Institute for Nuclear Sciences, Gent

A survey is given of the past and present fundamental developments and prac tical applications of neutron activation analysis performed at the reactor THETIS of the Institute for Nuclear Sciences, Gent, which has already now f or more than 30 years played an internationally appreciated pioneering role in this domain. Whereas the applications were mainly dealing with the anal ysis of semiconductor and high-purity materials, biomedical matrices, geolo gical materials, environmental samples and artefacts, the developments were directed towards the elaboration of irradiation, separation and counting s chemes, the determination of nuclear activation and decay constants, and es pecially towards the introduction of a modern (so-called k(0)-) standardiza tion method which - especially combined with a dedicated software package s uch as KAYZERO/SOLCOI(C) issued by DSM Research - proved to make NAA to a m anageable and competitive analytical tool, nowadays applied in more than 50 NAA-labs worldwide.