This master thesis examines the concept of risk assessment for theSwedish power grid. The aim is further to find an optimal process forhow to conduct risk investigations and analyses for the consultingand engineering firm Pöyry Sweden AB. By presenting relevanttheoretical concepts of risk, security and descriptions of thedifferent stages in a recommended risk assessments process a companyspecific method has been defined. The study is based on interviewswith experts and previous research within the relevant field in orderto create a deeper understanding of the topic. The results show theimportance of choosing a suitable analysing technique to investigateevents that have been identified as risks for the Swedish power grid.These techniques should be chosen with regard to the quantitativedata available and the risks’ characteristics. The risks that havebeen focused on in this study are the ones that have a high impact onthe power system and its reliability but which occur with arelatively low frequency. This can be exemplified with theantagonistic risks which are highly unexpected and can cause greatsocial disasters. Due to the lack of prior experience and statisticalevidence it is advocated that creative processes are an effectivestrategy to identify and evaluate these kinds of risks. Regardingnature related risks the most advantageous method to investigatetheir probabilities and consequences is by using a semi quantitativeapproach. Both expert opinions and quantitative data need to beconsidered to generate the most reliable result.