In severe accidents the emergency response organization (ERO) will try to prevent, reduce, or delay large radioactive releases outside the nuclear power plant site. Almost all safety issues are resolved through operator actions during the response to a severe accident. Despite this, existing probabilistic safety assessments (PSAs) are not analyzing in detail the impact of the ERO's on post fuel damage actions. Furthermore, human reliability analysis (HRA) methods developed for treating proceduralized control room operators' actions are still used for dealing with ERO staff decisions and actions in severe accidents. This paper reports the findings from the NPSAG (Nordic PSA Group) and Nordic Nuclear Safety Research (NKS-R) project SITRON (SITe Risk Of Nuclear installations) regarding the Nordic nuclear power plants EROs arrangements and the piloted approach for quantifying the impact of EROs actions on the site risk. Better understanding and assessment of the EROs impact on severe and site-level accidents are necessary steps for further progress on severe accidents preparedness.