[en] The safe dismantling of a retired nuclear power plant was demonstrated by completion of dismantling activities for the Japan Power Demonstration Reactor (JPDR), March, 1996, which had been conducted since 1986. This project was a flag ship project for dismantling of nuclear power plants in Japan, aiming at demonstrating an applicability of developed dismantling techniques in actual dismantling work, developing database on work activities as well as dismantling of components and structures. Various data on dismantling activities were therefore systematically collected and these were accumulated on computer files to build the decommissioning database; dismantling activities were characterized by analyzing the data. The data analysis resulted in producing general forms such as unit activity factors, for example, manpower need per unit weight of component to be dismantled, and simple arithmetic forms for forecasting of project management data to be applied to planning another dismantling project through the evaluation for general use of the analyzed data. The results of data analysis could be usefully applied to planning of future decommissioning of commercial nuclear power plants in Japan. This report describes the data collection and analysis on the JPDR dismantling activities. (author)