# A Modeling of Human Reliability Analysis on Dam Failure Caused by Extreme Weather
## 4 Bayesian Network Construction
### Sensitivity Analysis
For the final result node, the Human Reliability node, the entropy reduction is performed using Equation (9) and the results are shown in Figure 13. Observation of the results obtained from the sensitivity analyses reveals that the factors with the greatest impact are Operator Psychological Responsibility, Operator Psychological Habits, Operator Quality Professional Skills, Task Single Time, Operator Psychological Attention. It can be observed that the higher-sensitivity ones are mainly related to the quality attributes of field operators, such as responsibility, habit, professional skill, attention, and mental quality. Due to the fact that operators are the main body of the monitoring and operation execution, the human behaviors are inevitably the most important factors affecting the human reliability. Also, Task Time has a direct impact on reliability. The Human Cognitive Reliability (HCR) methodology founded by the American Electric Power Research Institute EPRI is to quantify shift operations for a finite period of time, mainly considering the probability of operator error under time-critical emergency conditions [47]. This method utilizes the allowable time Td and execution time T1/2 for calculation, considering only the time factor. After the operator factors, there are the related factors of the organization, including training, management, culture, cooperation and so on. Organizational factors are the deeper factors affecting the accidents and have an impact on the final results by acting on the operators. Figure 13: Sensitivity analysis of the factors affecting human reliability. For the node Operator Psychological Responsibility, the factor with greater entropy reduction is firstly the Operator Psychological Habits, the personal habitat of the operator, which is not only inherent, but can be cultivated later on. This emphasizes the importance of the organization's selection and development of operators. Organization Atmosphere Management, Organization Atmosphere Training, Organization Atmosphere Culture, Organization Atmosphere Cooperation, and Technology Hardware Daily Management all have a significant impact on accountability after this. For Operator Psychological Habits, the main factor with higher entropy reduction is Operator Psychological Responsibility; the two directly reinforce and influence each other and are important reflections of the quality factor of the operator. The Operator Psychological Character is much less sensitive. This is followed by organizational factors related to Work Regulations, Management, Culture, and Training. For the factor Operator Quality Professional Skills, the factor with the highest sensitivity is Organizational Training, with an entropy reduction about twice that of the second-place Organization Culture, and its entropy reduction value is also about twice that  
Figure 17: Sensitivity analysis of the factors affecting Task Single Time. Figure 18: Sensitivity analysis of the factors affecting Operator Psychological Attention. of the third-place Organization Management. After that, the personal factors of Experience, IQ, and Knowledge are the same. This can lead us to think about how to reduce the error rate more efficiently and economically. For example, it is often difficult, even impossible, to improve the intelligence of operators, yet it is relatively easy to train them on the subject. For the factor Task Single Time, the nodes with large entropy reduction are Organization Atmosphere Cooperation, Task Single Complexity, Operator Physiological Natural Skills, Organization Atmosphere Management, Technology Hardware Daily Routine. And for Operator Psychological Attention, it is Technology Hardware Operability, Operator Psychological Emotions, Operator Physiological Ability, Operator Psychological Attitudes, and Environment Physical factors. Through the study of these influencing factors, it can be found that for the final human reliability, the first and foremost influence lies in the quality and psychological factors of the front-line operators themselves.