WF71: Create Hazard Diagram

Pre-Requisites

• A. FBD Model: contains model items defined with functions.
• B. SRA Module: access enables ability to edit Hazard Diagram.

Detailed Steps

1. Access Hazard Diagram viewer — using the project explorer, select a model item and right-click to select "Hazard Diagram."
2. Populate from Hazard Taxonomy (Concepts) — use the Hazard Concepts Taxonomy Library to build Hazard Diagrams. A Hazard diagram consists of Hazard Sources, Initiating Mechanisms, and Target/Threat Outcomes. The Auto design feature can be used to construct pre-defined hazard diagrams and can be toggled on/off through the hazard concept menu button.
3. Populate Hazard Diagram (Connections) — by selecting a hazard concept, create appropriate pathing between Hazard sources, Initiating mechanisms, and Target/Threat outcomes. Where applicable, existing failure diagram functional failure modes can be connected to the hazard path through a hazard source concept.
4. Refine Hazard Diagram — where necessary, refine hazard concepts through the deletion of concepts (right-click -> delete) and connectivity. If required, define custom concept display names and narratives in the 'General' tab of the properties viewer.
5. Assign software hazard designation — if the hazard is related to software, update the software control parameter value to be greater than or equal to 1 in the 'MIL-STD-882E' section within the Properties window.
6. Hazard Diagram Created for the selected model item — proceed to Perform System Hazard Analysis or Perform Software Hazard Analysis.

Screen-by-screen detail (from embedded screenshots)

• Step 1: Access Hazard Diagram viewer — Project Explorer, right-click a model item (e.g. "Control Unit" under Power Generation) > select "Hazard Diagram" (alongside New, System Model, Failure Diagram, Functions, Maintenance Actions, Cut/Copy/Paste). Opens the hazard diagram canvas for that item (e.g. "Control Unit") showing existing hazard concepts wired together: "Dielectric strength decreased (Control Unit)" -> "Intermittent operation"; "Property mismatch (Control Unit)", "Electrical potential decreased (Control Unit)", "Open circuit (Control Unit)" all feeding via OR-gate nodes into "Process Continuous Amplitude (Control Unit)". A side panel shows "Failure Concepts" and "Hazard Concepts" taxonomy trees (e.g. Environment, Human, Physical > Chemical, Electrical, Explosives, Fire > Electrical Fire/Gas Fire/Liquid Fire/Metal Fire/Solid Fire, Motion, Technical).
• Step 2: Populate Diagram from Hazard Taxonomy — Three taxonomy panels for the three hazard-diagram layers: "Hazard Sources" (e.g. Environment > Radiation > Alpha/Beta/Electromagnetic Interference/Gamma/Infrared/Laser/Microwave/Neutron/Non-ionizing Radiation [selected]/Radiofrequency Radiation), "Initiating Mechanisms" (e.g. Environment > Temperature > Extreme Cold/Extreme Heat [selected]; also Climate, Motion, Radiation, Storage, Weather; Human; Physical; Technical), and "Target/Threat Outcomes" (e.g. Environmental, Financial, Intellectual Property, Operational, Reputation, Safety > Injury or Occupational Illness, Loss of Life [selected], Negligible Level of Harm, Permanent Partial/Total Disability Disease or Injury; System). Selecting/dragging concepts populates the diagram canvas with new nodes (e.g. Non-ionizing Radiation, Electromagnetic Interference, Extreme Heat, High Temperature, Loss of Life, Severe Financial Impact, Major Loss of Operational Capability, Dielectric strength decreased, Intermittent operation) which then get wired to the existing failure-diagram-linked nodes (Property mismatch, Electrical potential decreased, Open circuit) feeding into "Process Continuous Amplitude (Control Unit)".
• Step 3: Populate Hazard Diagram (Connections and Logic Gates) — Draw connections between hazard source -> initiating mechanism -> target/threat outcome nodes (e.g. Non-ionizing Radiation -> Extreme Heat -> Major Loss of Operational Capability; Electromagnetic Interference -> High Temperature -> Severe Financial Impact / Loss of Life). Right-click a target/threat outcome node (e.g. "Major Loss of Operational Capability") > New > "AND Gate" to add a logic gate; by default connections use an OR Gate. Example: an AND Gate requires both "Extreme Heat" and "High Temperature" to trigger "Major Loss of Operational Capability", whereas the default OR Gate triggers if either occurs.
• Step 4: Refine Hazard Diagram — Right-click nodes/connections to Delete, Cut/Copy/Paste, Zoom In/Out, or open "Control Measures". Use the Properties panel (tabs General, MIL-STD-882E) to edit Name, Category (e.g. "Financial"), Description (e.g. "5,000,000 to 10,000,000"), and Narrative (e.g. "Failure of Control Unit can lead to electrical faults and overheating, resulting in fire, system damage, operational downtime, and repair or replacement costs within the range of $5M to $10M") for a selected node such as "Severe Financial Impact".
• Step 5: Assign Software Hazard Designation — In Properties > MIL-STD-882E tab for a node (e.g. "Electromagnetic Interference"): Probability slider (1-10, e.g. 10.0 "Very High") and "Software Control" slider (0-10, e.g. 8.5 "Autonomous"). Another node ("High Temperature"): Probability 10.0 "Very High", Software Control 7.0 "Semi-Autonomous". A Target/Threat node ("Severe Financial Impact"): Probability 4.0 "Remote", Severity 7.0 "Moderate" (no Software Control field, since it's an outcome node not an initiating mechanism).