Resumen
Greek Research Reactor (GRR-1) is a light-water cooled and moderated heterogonous research reactor with a thermal output of 5 MW. The reactor is in extended shutdown for refurbishment since 2004. The refurbishment plan includes replacement of the Primary Cooling System. The decommissioning strategy consists of dismantling and removal of the bulky elements as whole pieces with-out preliminary segmentation and cutting and dis-mantling of the pipe works and PCS support structures. In this work the dose assessment and methodology in the context of planning for decommissioning of the PCS is presented.