An Integrated Safety Assessment Methodology (ISAM) - Rev 1.1 - 2011

The Generation IV (Gen IV) International Forum’s Risk and Safety Working Group (RSWG) has developed the Integrated Safety Assessment Methodology (ISAM) to evaluate and document the safety of Gen IV nuclear systems throughout their development cycle. Unlike earlier generations of nuclear technology that applied safety analysis to mature designs, ISAM aims to build safety into the design from the earliest stages, influencing concept and design development. ISAM is a toolkit designed to improve safety, reduce costs, and shorten the technology development cycle. It can be applied in three main ways: during concept development and design phases to understand and mitigate safety vulnerabilities, at various points to objectively assess risk contributors and safety margins, and in the late design stages to evaluate safety relative to objectives or licensing criteria. ISAM’s elements support each other, providing a comprehensive understanding of safety issues through tools such as Qualitative Safety Features Review (QSR), Phenomena Identification and Ranking Table (PIRT), Objective Provision Tree (OPT), Deterministic and Phenomenological Analyses (DPA), and Probabilistic Safety Analysis (PSA). Each tool addresses specific safety questions at different design stages, contributing to a robust safety assessment process. The methodology is designed to be flexible and iterative, ensuring that safety is integrated into Gen IV systems effectively and efficiently.