Fault Tree Analysis in Risk Assessment

Correct Answer: Top-down deductive analysis starting from the undesired event

In Fault Tree Analysis (FTA), the top-down deductive approach is the correct and most efficient methodology for identifying root causes of system failures. Here's why: Top-down analysis starts with the undesired event (called the 'top event') and systematically works downward to identify all possible ways this failure could occur. This method: - Provides a structured approach to trace failure paths - Helps identify all potential contributing factors - Allows for logical organization of multiple failure modes - Facilitates the identification of single point failures Why other approaches are less effective: Bottom-up analysis is more suited for FMEA (Failure Mode and Effects Analysis), not FTA. It's less efficient for identifying specific failure paths. Parallel system analysis examines components simultaneously, which can miss crucial sequential relationships between failures. Cross-sectional evaluation focuses on specific stages rather than the complete failure path, making it inadequate for comprehensive root cause analysis.

Correct Answer: The product of the individual probabilities of basic events linked through AND gates

In Fault Tree Analysis (FTA), the calculation of top event probability follows Boolean algebra rules based on the logical gate connections between events. For events connected through AND gates, we multiply their individual probabilities since all events must occur simultaneously for the top event to happen. For events connected through OR gates, we add their probabilities (minus any intersection to avoid double counting) since any single event can trigger the top event. The correct answer focuses on the AND gate calculation, which is a fundamental principle in FTA. The other options are incorrect because: - Simply summing all probabilities overlooks the logical relationships between events - Multiplying by the number of gates has no basis in probability theory - Taking a statistical average would not reflect the actual failure paths in the system

Correct Answer: An undeveloped event that needs further investigation

In Fault Tree Analysis (FTA), the diamond symbol specifically represents an undeveloped event that requires additional investigation or analysis. This symbol is important in FTA because it indicates areas where: - More data collection is needed - Further breakdown of the event may be necessary - The analysis is incomplete or requires additional resources The other options are incorrect because: - A basic event with known probability is represented by a circle symbol - Secondary sequential events are typically shown using AND/OR gates - Intermediate events are usually represented by rectangles in fault tree diagrams Understanding these symbols is crucial for proper risk analysis and documentation in project management, as they help identify areas that need more detailed examination and risk assessment.