Development of EMBRACE-Support Software: An Integrated System for Empirical Human Reliability Analysis in Digital Nuclear Control Rooms

The increasing digitalization of nuclear power plant control rooms and the diversification of human-machine interfaces have created pressing needs for human reliability analysis (HRA) methods based on plant-specific data. The EMBRACE (Empirical data-Based crew Reliability Assessment and Cognitive Error analysis) method integrates empirical HuREX (Human Reliability data Extraction) database measurements with structured modeling of human failure events. While the method has been theoretically validated, its practical implementation in risk assessment workflows remains limited by the absence of a dedicated software system. This paper presents the development of EMBRACE-Support Software (ESS), a dedicated computational system that operationalizes the EMBRACE method for digitalized environments. ESS features a modular architecture that interconnects heterogeneous databases-including those for procedure structures, primitive error probabilities, and time distributions-to automate the quantification process. The software also provides interactive visualization capabilities by generating procedure flowcharts and timeline graphs that allow analysts to intuitively decompose tasks and compare the time available and the time required. Through a systematic linking of these databases with the user interface, ESS automates the complex computational logic for both failure probability of timely performance (FPtp) and failure probability due to cognitive error in procedural tasks (FPce). At present, the software is currently undergoing verification through pilot user tests. Preliminary results indicate significant improvements in reproducibility, traceability, and computing efficiency compared to manual EMBRACE calculations. Ongoing development efforts are also being directed toward automating the documentation of both the analysis workflow and its results, aiming to improve the usability and efficiency of HRA application.

Keywords: EMpirical data-Based crew Reliability Assessment and Cognitive Error analysis (EMBRACE), Human error probability, Human reliability analysis, Support software, Probabilistic risk assessment.