This Report summarizes the results of a research carried out in the year 2007 under the SONIS (Safety of Nuclear Installations) programme for 2007, Task 1.1.1, Maintenance effectiveness indicators and risk monitors. The research was based on the survey of the experience of European nuclear utilities in the use of maintenance performance indicators at selected European nuclear utilities. The survey results proved the validity of the specific maintenance performance indicators selected for the maintenance performance monitoring framework proposed by IE/JRC and published in the EU Report 22602. The obtained results provide good basis for further development and implementation of the proposed maintenance monitoring system. The analysis of the survey results revealed additional maintenance aspects critical to the effectiveness of maintenance programme. All these topics will be carefully analysed in the next steps of the research in connection to their coverage in the maintenance monitoring system and identification of critical items that could be subject for the further activities in the SONIS Research program.JRC.F.5-Nuclear operation safet
