Quantitative Risk Assessment

Quantitative Risk Assessment (QRA) is a tool for companies that are looking to improve their safety management systems beyond the primary analysis provided by a PHA or LOPA.

QRA involves the combination of accident consequences and probabilities into various risk measures including indices, individual risk, and societal risk. Results of the analyses are presented as point estimates, risk contours, or frequency-number (F-N) curves. Usually, the risk measures are compared with risk tolerance criteria such as limit lines. Risk sensitivities, importances and uncertainties are also evaluated so they can be considered in decision making. QRA is used by companies in several ways including analyzing and ranking scenarios identified in process hazard analysis (PHA), providing quantitative data for use in decision making on risk, and comparing alternative process design options.

Details

Services offered: 

• hazard identification (HAZID);
• accidental release scenario development;
• frequency analysis (Event Tree/ Fault Tree);
• consequence models for fire, explosion and toxic vapor dispersion;
• cost-benefit analysis;
• presentation of risk results (individual risk, societal risk, financial risk, business risk).

A project overall includes calculations of scenario probabilities and consequences to determine scenario risk.  All results are provided in a report that documents the results of the calculations.

Other Information

Increasingly, companies recognize that reliance on purely qualitative risk analysis is insufficient where high consequence, low probability accidents are concerned. Qualitative risk estimates are subjective. Quantitative analysis provides a sounder basis for decision-making regarding the tolerability of the risk of catastrophic accidents.