The transformation of traditional power systems to smart grids brings significant benefits, but also exposes the grids to various cyber threats. The recent effort led by US National Electric Sector Cybersecurity Organization Resource (NESCOR) Technical Working Group 1 to compile failure scenarios is an important initiative to document typical cybersecurity threats to smart grids. While these scenarios are an invaluable thought-aid, companies still face challenges in systematically and efficiently applying the failure scenarios to assess security risks for their specific infrastructure. In this work, we develop a model-based process for assessing the security risks from NESCOR failure scenarios. We extend our cybersecurity assessment tool, Cyber-SAGE, to support this process, and use it to analyze 25 failure scenarios. Our results show that CyberSAGE can generate precise and structured security argument graphs to quantitatively reason about the risk of each failure scenario. Further, CyberSAGE can significantly reduce the assessment effort by allowing the reuse of models across different failure scenarios, systems, and attacker profiles to perform what if? analysis.