An empirical study on the basic human error probabilities for NPP advanced main control room operation using soft control

Abstract

By adopting new human-system interfaces that are based on computer-based technologies, the operation environment of main control rooms (MCRs) in nuclear power plants (NPPs) has changed. The MCRs that include these digital and computer technologies, such as large display panels, computerized procedures, soft controls, and so on, are called Advanced MCRs. Among the many features in Advanced MCRs, soft controls are an important feature because the operation action in NPP Advanced MCRs is performed by soft control. Using soft controls such as mouse control, touch screens, and so on, operators can select a specific screen, then choose the controller, and finally manipulate the devices.

However, because of the different interfaces between soft control and hardwired conventional type control, different basic human error probabilities (BHEPs) should be considered in the Human Reliability Analysis (HRA) for advanced MCRs. Although there are many HRA methods to assess human reliabilities, such as Technique for Human Error Rate Prediction (THERP), Accident Sequence Evaluation Program (ASEP), Human Error Assessment and Reduction Technique (HEART), Human Event Repository and Analysis (HERA), Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR), Cognitive Reliability and Error Analysis Method (CREAM), and so on, these methods have been applied to conventional MCRs, and they do not consider the new features of advance MCRs such as soft controls. As a result, there is an insufficient database for assessing human reliabilities in advanced MCRs.

In this paper, BHEPs in a soft control operation environment are investigated empirically for BHEPs to apply advanced MCRs. A soft control operation environment is constructed by using a compact nuclear simulator (CNS), which is a mockup for advanced MCRs. Before the experiments, all tasks that should be performed by subjects are analyzed using one of the task analysis methods, Systematic Human Error Reduction and Prediction Approach (SHERPA). Human errors are then checked to analyze BHEPs, human error mode, and the cause of human error when using soft control.