Quantitative risk assessment (QRA) is a formalised specialist method for calculating individual, environmental, employee and public risk levels for comparison with regulatory risk criteria.
Satisfactory demonstration of acceptable risk levels is often a requirement in, for example, the approval of major hazard plant construction plans, or significant changes to operations which may include areas such as plant modification and changes in operational manning levels.
Facilities requiring QRA studies may include production and processing facilities, high pressure pipelines or storage and importation sites including liquefied natural gas (LNG).
QRA may be a requirement of applicable legislation and/or internal company governance to show that risks are identified and controlled to an acceptable level. The criteria for risk acceptability may be defined by local regulations or company / investor policy.
Typically, a QRA can be defined as the formal and systematic approach of identifying potentially hazardous events, estimating the likelihood and consequences of those events, and expressing the results as risk to people, the environment or the business.
The method may include some or all of the following:
- An analysis of the severity/consequence of accident scenarios
- Predicted number of fatalities/casualties for each scenario
- Individual risk
- Group/societal risk
- Potential loss of life
- Location specific risk
- Further analysis of accident scenarios that are ALARP (As Low As Reasonably Practicable)
- Preventative/mitigation measures
- Sensitivity of results to uncertainties and assumptions.
DNV GL is able to support it's clients through, for example, the undertaking of QRA studies to identify potential accident scenarios which contribute most to the overall risk of an operational facility, allowing focus to be placed on means to minimise or mitigate risks to meet appropriate acceptability criteria and/or demonstrating that the risks are as low as reasonably practicable (ALARP).