Risk-informed commissioning assessment using PSSR maturity as a barrier integrity proxy

Pre-Start-Up Safety Review (PSSR) is routinely used as a compliance checklist, but its records are rarely converted into quantitative barrier-layer measures or linked to start-up performance. This study develops a risk-informed framework that uses PSSR maturity as a multidimensional proxy for pre-operational barrier integrity. Its novelty lies in integrating maturity measurement, barrier-gap diagnosis, risk-based prioritization, and empirical assessment of commissioning stability. A PSSR Maturity Index (PMI) was constructed across five dimensions: design conformity, mechanical completion, safeguard readiness, procedural closure, and personnel competency. The framework was evaluated using 350 PSSR evaluations from commissioning of a Heat Recovery Steam Generator at a combined-cycle power plant. Associations with stable start-up were examined using multivariable logistic regression, bootstrap resampling, and 10-fold cross-validation. Safeguard readiness (OR = 1.86) and mechanical completion (OR = 1.58) showed the strongest associations, whereas procedural closure was not independently associated with stability. The model showed modest explanatory capacity but limited discrimination (Nagelkerke pseudo- R ²  = 0.163; AUC = 0.624), indicating that the readiness dimensions captured partial rather than comprehensive signals of commissioning vulnerability. The framework’s primary contribution is diagnostic: it distinguishes documentary completion from functional barrier readiness and converts routine PSSR evidence into barrier-specific gaps and risk-ranked corrective priorities. Although the findings are case-specific, the framework provides a reproducible basis for cross-site validation.