Report review summary
A complete QRA report should document the study objective, hazardous inventory, credible scenarios, failure frequencies, consequence models, weather and population assumptions, individual-risk contours, societal-risk F-N curves, dominant contributors, ALARP evaluation and prioritised mitigation. The calculations must be traceable enough for an independent reviewer to reproduce the decision basis.
A QRA report is not simply a collection of coloured contours. Its purpose is to connect facility data and assumptions to numerical risk results and then to practical decisions. This guide provides a recommended report structure and a review checklist for clients, regulators, engineering teams and insurers.
For a full study, see Elion’s QRA service. For calculation methods, see the QRA methodology guide.
Recommended QRA report structure
1. Executive summary
State the facility, decision objective, principal hazards, headline risk results, acceptance basis, dominant contributors and priority recommendations. Avoid introducing numbers that cannot be traced to the main report.
2. Study scope and boundaries
Define the battery limits, operations included, project stage, onsite and offsite receptors, applicable requirements, modelling tools, exclusions and report limitations.
3. Facility and process description
Describe the plot plan, processes, storage, transfer systems, hazardous materials, operating conditions, isolation philosophy, detection and emergency systems. Drawings should carry revision numbers.
4. Data and assumption register
List each material input and identify whether it was client-provided, site-verified, calculated, referenced or assumed. Uncertainty and conservative assumptions should be visible.
5. Hazard identification and scenario register
Document the HAZID method and each credible release scenario, including equipment, substance, inventory, pressure, temperature, hole size, release direction, duration and isolation response.
6. Frequency analysis
Provide initiating-event frequencies, data sources, event trees, ignition probabilities, safeguard credit, weather probabilities and the calculation used to obtain each outcome frequency.
7. Consequence modelling
Explain discharge, dispersion, pool fire, jet fire, flash fire, BLEVE, vapour-cloud explosion and toxic models as applicable. State software versions, model options, endpoints and limitations.
8. Weather, occupancy and population
Document wind-speed and direction distributions, atmospheric stability, surface conditions, onsite occupancy, offsite population and sensitive receptors. Explain day/night or seasonal treatment where material.
9. Consequence results
Provide scenario-level effect distances and maps. Tables should allow reviewers to identify the scenario, endpoint, weather case and result without interpreting images alone.
10. Individual and societal risk
Present individual-risk contours and societal-risk F-N curves where required. State the acceptance criteria, population basis and treatment of onsite and offsite exposure.
11. Dominant risk contributors
Rank the equipment, scenarios and outcomes contributing most to total risk. This analysis should drive the mitigation programme.
12. ALARP and recommendations
Evaluate credible risk-reduction options. Each recommendation should identify the risk driver, proposed control, responsible discipline, priority and expected effect on risk.
13. Conclusions, limitations and action register
Summarise residual risk and decisions without overstating model precision. Include open data gaps, conditions of validity and the events that should trigger revalidation.
14. Technical appendices
Include calculation records, frequency tables, event trees, substance data, input registers, model-output references, drawings, contour files and review-comment close-out.
Numerical outputs normally expected
| Output | Typical presentation | Review question |
|---|---|---|
| Release frequency | Events per year | Is the source and calculation traceable? |
| Thermal radiation | kW/m² effect distances | Are exposure duration and endpoint basis stated? |
| Explosion overpressure | bar or kPa contours/distances | Are congestion and confinement assumptions suitable? |
| Toxic exposure | Concentration and exposure-time endpoint | Is the selected health criterion documented? |
| Individual risk | Annual-frequency contours, commonly 10−4 to 10−7/year | Do the maps match numerical results? |
| Societal risk | F-N curve | Are population and occupancy inputs defensible? |
The correct endpoints and acceptance criteria depend on the facility, authority and decision objective; the values above describe common presentation formats, not universal approval limits.
QRA report review checklist
- Scope and decision objective are explicit
- Inventories and plot plans match current project documents
- Scenario register covers process, storage and transfer hazards
- Frequency data and event trees are traceable
- Safeguard credit is justified by reliability assumptions
- Consequence models match the release physics
- Weather, occupancy and population data are appropriate
- Contour drawings agree with result tables
- F-N calculations use the documented population basis
- Dominant contributors are identified
- Recommendations address those contributors
- ALARP conclusions evaluate practicable alternatives
- Limitations and revalidation triggers are stated
- Independent review comments are closed
Common report defects
- Copy-pasted site names, inventories or assumptions
- Only consequence distances presented as a “QRA”
- Risk contours without frequency calculations
- Unexplained software defaults
- Different effect zones in the QRA and emergency plan
- Recommendations unrelated to the dominant scenarios
- No calculation or model audit trail
How to use the QRA report after issue
Translate recommendations into the project or site action-tracking system. Preserve safeguards credited in the model through inspection, proof testing and management of change. Use the scenario and effect-distance data to check emergency plans, occupied-building decisions and future modifications.
When should the report be revalidated?
Review the QRA when hazardous inventories, equipment, pressure, chemistry, layout, isolation, detection, occupancy or surrounding population materially change; after a significant incident; or when an approval, standard or management-of-change process requires it.
Frequently asked questions
Can an executive summary replace the technical report?
No. The summary supports management decisions, but the technical basis must remain available for engineering and regulatory review.
Should the client receive model files?
The contract should define native model files or alternative reviewable outputs. At minimum, the client should receive sufficient input and calculation records to audit the conclusions.
Who should approve a QRA report?
Technical approval should involve the study lead and an independent checker, while the facility owner remains responsible for accepting assumptions, implementing actions and making risk decisions.
Elion can prepare a complete QRA report or independently review an existing study. Send the report or facility brief for a scoped technical review.