Quantitative Risk Assessment for Hydrogen Systems: Model Development and Validation

Quantitative Risk Assessment (QRA) is a risk-informed approach that considers past performances and the likelihood of events and distinguishes must-haves from nice-to-haves. Following the approach applied for the HyRAM code, developed by the Sandia National Laboratories, a QRA toolkit for hydrogen systems was developed using MATLAB by Canadian Nuclear Laboratories (CNL). Based on user inputs for system components and their operating parameters, the toolkit calculates the consequence of a hydrogen leak from the system. The fatality likelihood can be estimated from the severity of a person’s exposure to radiant heat flux (from a jet fire) and overpressure (from an explosion). This paper presents a verification and validation exercise by comparing the CNL model predictions with the HyRAM code and available experimental data, including a QRA case study for a locomotive. The analysis produces risk contours recommending personnel (employees/public) numbers, time spent, and safe separation distances near the incident (during maintenance or an accident). The case study demonstrated the importance of hydrogen leak sensors’ reliability for leak detection and isolation. The QRA toolkit calculates a more practical value of the safe separation distance for hydrogen installations and provides evidence to support communication with authorities and other stakeholders for decision-making.