IS 19749 : 2026

Probabilistic Risk Assessment of Nuclear Power Plants — Guidelines

This Indian Standard provides a standardized framework for conducting Probabilistic Risk Assessment (PRA) of nuclear power plants to support risk-informed decision-making. The standard has been developed to harmonize PRA methodologies and improve the credibility, consistency, and quality of risk assessments used during the design, operation, maintenance, and regulatory review of nuclear facilities. It primarily focuses on Level-1 PRA for internal events occurring during full-power operation conditions.

This outlines the objectives, scope, terminology, and application requirements for PRA studies. It aims to identify design and operational vulnerabilities, support performance-based safety decisions, and ensure that risk models accurately represent the “as-built” and “as-operated” plant configurations. Although developed mainly for commercial nuclear power plants, the methodology may also be adapted for research reactors and other safety-critical facilities.

It specifies detailed technical requirements covering plant familiarization, core damage definition, initiating event analysis, accident sequence modelling, success criteria, system modelling, common cause failure analysis, human reliability analysis, data assessment, risk quantification, uncertainty analysis, sensitivity analysis, and importance analysis. These elements collectively help estimate core damage frequency and identify significant contributors to plant risk.

This also emphasizes quality assurance, documentation, software validation, configuration control, and independent peer review. It requires qualified PRA analysts, systematic verification and validation processes, and comprehensive review mechanisms to ensure technical adequacy and regulatory acceptance. By providing a unified and technology-neutral approach, the standard strengthens nuclear safety management and enhances confidence in risk-informed decision-making.

Last Updated on June 10, 2026