Question

3. A certain emergency cooling water injection system contains two branches in parallel. Each branch consists of a pump, a valve, and a nozzle. Dependent failure is estimated at 0.05. Failure rate on demand ()is 1E-4 for pump. 5E-6 for valves, and 2E-8 for nozzles. The pump failure rate to nn a) is 0.01 year. The pump mission time (t) is 5 hours. Develop a fault tree including both independent and common cause failure for the top event of failure to inject cooling water Identify the cut sets. Identify the minimal cut sets. Find the probability of the top event using the rare events approximation. a. b. c.

Answer 1