Risk Assessment: Tools, Techniques, and Their Applications

Chapter 12

Event Tree and Decision Tree Analysis

Two of the largest nuclear accidents, Three Mile Island and Chernobyl, partially resulted from decisions made on the part of the power plant operating or engineering staff. In the case of Chernobyl, the accident was the result of a very bad decision on the part of the engineering staff who decided to run a test while the reactor was at low power. Three Mile Island accident, on the other hand, was initiated by a hardware failure but escalated when the operating crew decided to switch off the automatic safety system. The case study at the end of the chapter will analyze a portion of the Chernobyl event using an event tree.