GRIF | ETree - Assessing risk using event trees (Reliability/Safety Analysis)

• Creating event trees is easy via the intuitive graphical interface to which barriers can be added after an initiating event (gas leak, supply loss, overflow, etc.). Each scenario (known as a sequence) is thus defined by a succession of barrier failures and successes.
• Each sequence has a consequence chosen from a list created by the user. A risk is defined for each consequence, which can then be positioned on the X-axis of the risk matrix. The software then calculates the frequency of the consequence and assigns it to the Y-axis. The frequency of initiating events and the probability of safety barrier failure can be:
  • Either constant, following a probability law (Exponential, Weibull, Periodic Test, etc.);
  • Or, defined by another type of model: fault tree, reliability block diagram, safety instrumented loops via the Boolean module.

Multiple risks :

• Several risk matrices can be defined (human, financial or environmental, for example). 
• You can define the level of criticality of each one: moderate, serious, major, etc.
• A risk is assigned to each matrix for each consequence, so that consequences can be classified as catastrophic in human terms but moderate in financial terms, or vice-versa.

• User-friendly templates/models:  Do you regularly conduct studies using the same safety barriers? With GRIF ETree, you can create templates with one or several pre-configured barriers and risk matrices. If you want to create a new event tree, all you have to do is open the template and enter the parameters/coefficients.
• Calculating the frequency of each consequence over time: Risk matrices indicate an average frequency. However, when the initiating event or barriers are no longer constants, it may be necessary to show the frequency variation of a sequence (scenario) or of a consequence over time.

• Option to automate calculations (batch runs) and draw variations for sensitivity analysis.
• Results are stored in the document and can be exported in a variety of formats (csv, XML, Excel, etc.).
• Results can be viewed as line graphs, pie charts or histograms.
• Printing in PDF vector format produces high-quality images and the files are small enough to be sent by email, even if the document contains hundreds of pages.
• External files (PDF certificates, system images, etc.) can be added to the document and incorporated into the full report.
• Interaction with the operating system: option to copy/paste either to or from word processing software, spreadsheets, or presentation tools.
• Specific report containing all matrices.

The ETree module is part of the GRIF Boolean package. Calculations can be performed in the same document using Event Trees (ETree), Fault Trees (Tree), Reliability Block Diagrams (BFiab), Safety Instrumented Systems (SIL), Reliability Network (Reseda), or Bow-Tie / LOPA tables (Risk). 
Models can be linked together, and a link can define any object (Event, Block, Barrier, Network node, etc.) using any model: Fault Tree, Block-Diagram, SIS, Event Tree, etc.

For example, initiating events and barriers can be defined using a Fault Tree created with the Tree module, or an SIF via the SIL module. ETree is not limited to an independent layer of protection: barriers can share common components and the computation engine will process the dependencies.