"Electric utilities normally plan for the possibility of one, or occasionally two, independent failures of major equipment without their customers suffering any significant outage. If the system can be better protected, or made sufficiently resilient to withstand greater levels of damage, then the risk of a major, long-term blackout will be reduced. However, any such measures will cost money. Utilities are taking some steps, but apparently, generally consider the risk to be too low to warrant large expenditures […]. However, the consequences of a major, long-term blackout are so great that there is a clear national interest involved. Steps that may not be worthwhile for individual utilities could make sense from the national perspective. The purpose of this report is to explore the options for reducing vulnerability and place them in context. It first reviews the threat from both natural disasters and sabotage to determine what damage might occur. However, an analysis of the probability of any of these threats materializing is beyond the-scope of this study. Chapter 3 reviews the impact of major blackouts that have occurred, in order to help understand the costs of an even greater one that might be experienced eventually. Chapter 4 estimates the effect on the system when various critical components are damaged, and how the system can be restored. Chapters 5 and 6 describe present and potential efforts to reduce vulnerability. Finally, chapter 7 suggests how Congress could act, depending on how seriously the problem is viewed."