Derivation of a societal risk acceptance criterion for major accident hazard installations in Sri Lanka

•Societal risk acceptance criterion based on the FN Curve is proposed for Sri Lanka.•Natural disasters in Sri Lanka pose a higher risk than from technological disasters.•Proposed criterion line is risk neutral with a slope of −1.•The anchor point of the criterion line is 10 fatalities per 10,000 years.•Benchmarking of Sri Lanka’s societal risk acceptance criterion is essential. The usage of risk acceptance criteria for preventing major accident hazards (MAH) in chemical industrial installations is not widely practiced in Sri Lanka at present. This paper attempts to derive a societal risk acceptance criterion for MAH installations in the Sri Lankan context. In the absence of a precedent for a “societal risk acceptance criteria” in Sri Lanka a reference criteria or baselines were developed initially based on historical data using an empirical deductive approach. Disasters resulting from natural and technological events were considered. The level of risk is presented in the form of a Cumulative Frequency, F (N) vs Fatalities, N curve or FN curve. Two FN curves for natural disasters were compared with one FN curve for technological disasters to select a suitable reference or baseline. The selected baseline was then compared with internationally accepted societal risk acceptance criteria for the two major characteristics of the criteria line, slope and anchor point. Based on this comparison a line having a slope of −1 and an anchor point of (10, 10−4) is proposed as an initial estimate for the societal risk acceptance criterion.