Abstract
It is currently possible to say that there is consensus among experts that safety considerations are most effective when accounted for throughout the critical systems life cycle, starting from their conceptual design stage. However, this was not always the case and the available tools and techniques for safety evaluations were traditionally developed with the purpose of analyzing already installed systems, making it possible to identify expected failure phenomena and mechanisms just in more advanced stages of the system’s life cycle. With the evolution of the accidents studies, techniques applicable to the pre-operational phases were developed in order to reduce the risks posed by the system operation. Complementarily, as a fundamental part of risk analysis, Human Reliability Analysis (HRA) have a potential contribution for designing new systems. For this, it is essential to develop models able to feed analyzes at the conceptual design stage and to bring results that can support the decision-making. The Technique for Early Consideration of Human Reliability (TECHR) was developed for this purpose. This technique is based on the use of different sources of information to obtain probability estimates of various human error types that may occur during a specific action, and to estimate human error probabilities of generic actions. This paper presents a real application of a human performance model obtained by TECHR in specifying the maximum acceptable probability of failure on demand (PFD) and the maximum spurious operation frequency (SOF) of the Safety Control System (SCS) and of the SCS-D (a redundant system for the SCS) of a Floating Nuclear Power Plant (FNPP), incorporating the data presented in its Probabilistic Safety Assessment (PSA). This application showed the TECHR potential contribution to an SCS specification.
