Human Reliability Study of LOCA Event on Dhruva Simulator

Human error probability is an input to the assessment of risk in Probabilistic Safety Assessment (PSA) of nuclear and non-nuclear facilities. Nuclear safety not only depends on the reliability and safety of the Structures Systems and Components (SSCs) but also largely depends on human factors and interaction of operators with machines. Simulators greatly support in the training and transfer of knowledge to the plant operators. A full scope simulator was developed for a more than 30 years old, 100 MW research reactor Dhruva at BARC Trombay. The simulator was so designed that over and above training of the plant personnel, it will be used for safety studies in the area of reactor physics and thermal hydraulics. The interface was designed to support the interaction of the operators with the simulator through virtual panels supported by touch screens with high fidelity graphic displays. Important Postulated Initiating Events (PIEs) like Loss of Offsite Power, Loss of Coolant Accident, Loss of Regulation Incident, etc. have been modelled. This information will provide an insight to verify and validate the plant Emergency Operating Procedures (EOPs). Experiments were conducted on the simulator for Loss of Coolant Accident (LOCA). The break size was varied to have small as well as high leakage rates. The operators involved in the LOCA experiments had experience ranging from few years to nearly a decade. The diagnosis time and action were recorded for each experiment. These were used for estimation of analysis of human error probability (HEP) during LOCA.