A solar power station provides electricity to a mini-grid of a supercomputer facility. An auxiliary power generation sub-system was also designed to provide extra electricity in case the output power of the solar power station is not enough. The effectiveness of the sub-system is to be quantified using Event Tree Analysis. The auxiliary power generation sub-system has two independent and diverse power sensors, function as a trigger. If either of these are activated, an intelligent electric power converter will start to work. Once the converter works, a diesel generator will start to provide auxiliary power to the supercomputer facility through the converter. There is also a back-up gas turbine power generator to provide the auxiliary power if the diesel generator fail. If the converter doesn't work properly. the supercomputer is in a dangerous state. If the converter work well, but the diesel generator or gas turbine generator fails, the supercomputer is considered unsafe. An Event Tree Analysis for the subsystem is given in Figure Q14.1 including the failure probability of the various elements. The Initiating Event for the event tree is the power generated from the solar power station is below a certain value, which has been calculated as being 1.0 x10-1 per year. Calculate the probability of an unsafe or dangerous end state from this Initiating Event in a given year of operation. Output Power Low Power sensor 1 activated Power sensor 1 activated Converter Diesel Generator Gas turbine generator End state Safe 1- (1 x10-) 5 x10-3 Safe 2.5 x10-3 SUCCESS Unsafe 2.5 x10-3 Dangerous Safe 5 x10-3 Safe 2.5 x10-3 Unsafe FAILURE 1 x10-3 2.5 x10-3 Dangerous 2.5 x10-3 1.0 x10-1 Dangerous