Summary form only given. A comprehensive methodology is developed for the analysis of power system vulnerability with respect to energy shortage, capacity shortage and power system failures. The basic method is risk analysis, where risk is defined in terms of the probability of events and their consequences. The objective is to identify medium and high-risk situations that require corrective actions. The method is applied to the Nordic power system. The results show that the system is in a medium risk state, implying the need to consider various measures. With respect to energy shortage, the probability of extremely high prices over a sustained period of time is once every ten years for today's system, and similar in 2010. With respect to capacity shortage, the vulnerability is expected to deteriorate towards 2010. With respect to blackouts, the risk is related to large blackouts in Southern Scandinavia, involving many consumers. There is concern with regard to the future effect of changed maintenance routines and reductions in qualified technical personnel