Quantitative risk assessment software

Quantitative risk assessment (QRA) software and methodologies give quantitative estimates of risks, given the parameters defining them. They are used in the financial sector, the chemical process industry, and other areas.

In financial terms, quantitative risk assessments include a calculation of the single loss expectancy of monetary value of an asset.

In the chemical process and petrochemical industries a QRA is primarily concerned with determining the potential loss of life caused by undesired events. Specialist software can be used to model the effects of such an event, and to help calculate the potential loss of life.

Software

• RBM II (Risk Based Management II) from the Dutch Government
• Phast Risk (formerly SAFETI) from DNV Software - Integrated Consequence and Risk modeling aimed at the onshore petrochemical and chemical process industry.
• Safeti-NL - Dutch National QRA Model. A custom implementation of the DNV Phast Risk QRA software. Usage is mandated in the Netherlands according to BEVI legislation.
• Shepherd - Frequency assessment software proprietary to Shell Global Solutions
• Riskcurves - Integrated QRA software from TNO
• Effects - Consequence Analysis and damage calculation software from TNO

The following products have been superseded, or are no longer available:

• Damage - Damage calculations to structures and individuals (now included in Effects) from TNO
• Riskplot - formerly of Four Elements Software, now part of ERM
• Offshore Hazard and Risk Analysis (OHRAT) - formerly of DNV Software
• Neptune - formerly of DNV Software
• PLATO - (formerly of Four Elements Software, now part of ERM ) See Journal of Loss Prevention Vol 7 no 4 July 1994 and Vol 10 no 4 July 1997

Limitations

Some of the QRA software models described above must be used in isolation: for example the results from a consequence model cannot be used directly in a risk model. Other QRA software programs link different calculation modules together automatically to facilitate the process. Some of the software is proprietary and can only be used within certain organisations.

Due to the large amount of data processing required by QRA calculations, the usual approach has been to use two-dimensional ellipses to represent hazard zones such as the area around an explosion which poses a 10% chance of fatality. Similarly, a pragmatic approach is used in the simplification of dispersion results. Typically a flat terrain, unobstructed world is used to determine the behaviour of a dispersing cloud and/or a vaporizing pool. This presents problems when the effects of non-flat terrain or the complex geometry of process plants would no doubt affect the behaviour of a dispersing cloud. Though they have limitations, the 2D hazard zone and simplified approach to 3D dispersion modelling allow the handling of large volumes of risk results with known assumptions for to assist in decision-making. The trade-off shifts as computer processing power increases.

The modeling of the consequences of hazardous events in a true 3D manner may require a different approach, for example using a computational fluid dynamics method to study cloud dispersion over hilly terrain. The creation of CFD models requires significantly more investment of time on the part of the modeling analyst (because of the increased complexity of the modeling), which may not be justified in all cases.

See also

RAM Analysis

• DNV MAROS from DNV Software
• RAM analysis by ProcessInt

Risk Based Inspection Software

• Riscwise RBI
• Orbit from DNV software

Consequence Analysis

• Some of the above software products can also be used for pure consequence analysis

Qualitative Risk Assessment

• The Asset Partnership QRA-toolkit

links to various government regulations

• Directive 96/82/EC (SEVESO Directive)
• Comah (UK regulations)
• BEVI Besluit externe veiligheid inrichtingen (RIVM guidelines on performing a QRA)
• A comparison of QRA software (American Soc Safety Engineers 7th Conference (Middle-East Chapter), March 2005

References