This special issue features selected papers from the ICONE-23 held May 17-20, 2015 in Makuhari, Chiba, Japan. About 700 technical papers and presentations were made during the ICONE-23 conference from 30 countries. We invited all authors to submit their augmented papers for journal publication consideration. More than 50 authors responded. Our special thanks go to all the authors for their ... [Show full abstract] valuable support and for giving us an opportunity to showcase a sample of their research and developmental activities. With the support from our authors, this issue is enriched with papers from a variety of engineering and scientific subjects related to the nuclear engineering and safety. During the editorial process we selected these papers for publication after a through peer-review process. The issue captures the fundamental principles, achievements, and practices developed during the recent years on the operation of the current fleet of nuclear power plants around the world. This is the first ICONE-based issue of the ASME Journal of Nuclear Engineering and Radiation Science, and we sincerely hope it will establish the Journal of Nuclear Engineering and Radiation Science as the home journal for papers presented at ICONE-series of conferences in the future.