Exam simulation 2021

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Name:___________________ ID:___________________ RELIABILITY, SAFETY AND RISK ANALYSIS: Exam Simulation (17/05/2021) Note: 1. Make sure to write your name and ID number 2. The exam consists of 2 numerical problems and 2 questions on the course topics 3. Exam time is 2 hours and 15 minutes Problem 1 (7.5 points) Consider the following system (reliability block diagram): A. Draw a fault tree for the failure of the system, i.e. “no connection between nodes “1” and “2” and write the corresponding structure function B. Obtain the reduced form of the structure function and find the minimal cut sets. C. Find the probability of the top event assuming that the component’s individual unreliabilities are: qA = 10-3 qB = 2x10-3 qC = 10-2 qD = 9x10-3 D. Consider a case in which A and B unreliabilities are due to internal component failures (A’ and B’) and to a failure of their electric power generator (G), with unreliabilities qA’ = 0.9 10-3, qB’ = 1.9 10-3 and qG = 10 -4. Assume that the same electric power generator is shared between A and B. Compute the top event probability in this case. Problem 2 (7.5 points) Consider a 2-out-of-4 parallel structure of identical components. sharing a common load. In normal operation, four components equally share the load; they may fail with failure rate 4 (exponential process). When one component fails, the remaining three have to carry the whole load and the failure rate immediately increases to 3 (exponential process); similarly, if another component fails, the remaining two carry the entire load with a failure rate increasing to 2 (exponential process). The repair process of the failed components does not start until at least two components are failed and it is characterized by a constant repair rate s. The repairmen team restores the…