Lessons Learned from the US HRA Empirical Study

The US Human Reliability Analysis (HRA) Empirical Study (referred to as the US Study in the article) was conducted to confirm and expand on the insights developed from the International HRA Empirical Study (referred to as the International Study). Similar to the International Study, the US Study evaluated the performance of different HRA methods by comparing method predictions to actual crew performance in simulated accident scenarios conducted in a US nuclear power plant (NPP) simulator. In addition to identification of some new HRA and method related issues, the study design of the US Study allowed insights to be obtained on some issues that were not addressed in the International Study. In particular, because multiple HRA teams applied each method in the US Study, comparing their analyses and predictions allowed separation of analyst effects from method effects and allowed conclusions to be drawn on aspects of methods that are susceptible to different application or usage by different analysts that may lead to differences in results. The findings serve as a strong basis for improving the consistency and robustness of HRA, which in turn facilitates identification of mechanisms for improving operating crew performance in NPPs.