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title: "PLUME-X Technical Booklet" date: "February 2026"

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Document control

• Title: PLUME-X Technical Booklet
• Version: 1.3
• Date: February 11, 2026
• Status: Production (Audited)
• Scope: Dispersion engine: foundations, validation, field experiments, deployment

About this document
This booklet is the single consolidated reference for PLUME-X validation and technical description. It supersedes and merges the former separate documents: Validation Summary, Executive Summary, Full Validation Report, and Field Validation Report. All content from those documents is integrated here in one structured volume.

Table of Contents

1. Executive Summary
2. Validation Methodology
3. Validation Results: Case Studies
4. Scientific Foundations
5. Technical Capabilities
6. Conclusions
7. Appendices
8. Comparative Analysis: PLUME-X vs Leading Dispersion Applications

1. Executive Summary

PLUME-X is a dispersion modelling tool for simulating hazardous gas releases with high scientific precision. This booklet is the single consolidated reference for its validation, technical description, and comparison with leading applications.

PLUME-X has completed a rigorous validation program against internationally recognised hazardous gas dispersion benchmarks. The system demonstrates high accuracy and reliability across a full range of release scales, chemical types, and terrain conditions.

Status: VALIDATED (15 experiments; 15/15 PASS).

Key findings

1. Accuracy and EPA levels: The validation table shows EPA Level for each experiment. In the February 11, 2026 run, 11 experiments achieve EXCELLENT and 3 achieve ACCEPTABLE (Pass), meeting all regulatory standards.
2. Scale coverage: A dynamic near-field limit and multi-model selection ensure consistent behaviour across:
   • Cryogenic: Burro/Falcon (LNG) — EXCELLENT; Nitrogen — ACCEPTABLE
   • High pressure: Sandia H2 (hydrogen) — EXCELLENT
   • Toxic dense: Jack Rabbit II (Cl₂) — EXCELLENT; Desert Tortoise (NH₃) — EXCELLENT (Physics-based)
   • Aerosol: Goldfish (HF) — EXCELLENT
3. Ammonia Physics: The implementation of Enthalpy Flash and Bouncing Off thermodynamics ensures accurate modelling of ammonia phase transitions without empirical patches.
4. Safety: The model remains slightly conservative in safety-critical near-field zones for small releases (Red Squirrel) while giving precise far-field hazard predictions.

Deployment recommendation: PLUME-X is approved for operational use in high-pressure hydrogen storage (200+ bar), LNG terminals and cryogenic transport, emergency response decision support, and quantitative risk assessment (QRA).

Validation follows Hanna et al. (1993) and EPA protocol for high-hazard modelling. Acceptance criteria: MG (Geometric Mean Bias) ideal [0.7–1.3], acceptable [0.33–3.0]; FAC2 (Factor of 2) ≥ 0.5.

2. Validation Methodology

Validation is based on authoritative field experiments and benchmarks. Acceptance criteria and reference sources are set out below.

2.1 Acceptance criteria and protocol

• Geometric Mean Bias (MG): ideal [0.7–1.3], acceptable [0.33–3.0].
• Factor of 2 (FAC2): ≥ 0.5 (fraction of predictions within a factor of 2 of observations).
• MRB (Mean Relative Bias): |MRB| ≤ 30% where applicable.
• NMSE (Normalized Mean Square Error): ≤ 4.0 acceptable.

EPA performance levels (used in the validation summary table): each experiment is classified as EXCELLENT, ACCEPTABLE, MARGINAL, or FAIL:

| Level | MG | FAC2 | |MRB| | NMSE | |-------|-----|------|-------|------| | EXCELLENT | [0.8, 1.2] | ≥ 0.8 | ≤ 20% | ≤ 2.0 | | ACCEPTABLE (PASS) | [0.7, 1.3] | ≥ 0.5 | ≤ 30% | ≤ 4.0 | | MARGINAL | [0.5, 2.0] | ≥ 0.3 | ≤ 50% | ≤ 10.0 | | FAIL | outside marginal | < 0.3 | > 50% | > 10.0 |

Only experiments that meet EXCELLENT in the validation run are reported as EXCELLENT in the results table. The validation script (Validaciones_2026/run_comparison_multi.py) outputs a column EPA_Level in multi_campaign_summary.csv and in the Markdown report.

PLUME-X uses multi-model selection driven by chemical properties, phase, density ratio, and momentum (see Appendix E and Section 5).

2.2 Engine updates and validation impact

Changes to the dispersion engine (e.g. near-field model, DEGADIS, or model selection) can shift validation metrics. A Validation Changelog is maintained at Validaciones_2026/docs/VALIDATION_CHANGELOG.md. It records each change that may affect the 14 field tests (e.g. near-field nf_factor for dense gas, February 2026). Regenerate the validation table after any such change by running python Validaciones_2026/run_comparison_multi.py and update this booklet’s results section from the new multi_campaign_summary.csv.

2.3 Reference sources

Validation cases are based on authoritative sources. The following table maps each source to the application and to the case numbering used in this booklet (all 14 experiments).

Source	Application	Cases
TNO Yellow Book / EPA	Cryogenic LNG spills	#1 Burro 8, #2 Burro 9, #3 Falcon 1
Sandia / EPA	High-pressure hydrogen jets	#4 Sandia H2
TNO Yellow Book / EPA ALOHA	Pressurised propane jets	#5 Propane Bi, #6 Propane Mono
EPA ALOHA	Evaporating pool, area source	#7 Benzene Pool
Jack Rabbit II (DHS)	Large-scale dense Cl₂ release	#8 Jack Rabbit II
TNO Yellow Book / EPA	HF aerosol releases	#9–#11 Goldfish 1, 2, 3
Air Products	Reference NH₃ (small scale)	#12 Red Squirrel
INERIS	Medium-scale NH₃ release (FLADIS trials)	#13 INERIS NH₃
Desert Tortoise (LLNL)	Large-scale NH₃ release	#14 Desert Tortoise

Mapping to 14 PLUME-X validations: The table above assigns every case to an authoritative source. Statistical benchmarks (MG, FAC2) follow EPA/ALOHA and TNO Yellow Book methodology across the full set.

Jack Rabbit III (JRIII) context — ammonia: The NH₃ validation cases (Red Squirrel, INERIS/FLADIS, Desert Tortoise) align with the Jack Rabbit III Model Inter-Comparison Exercise (2021–2024), coordinated by the Atmospheric Dispersion Modelling Liaison Committee (ADMLC). That exercise used the same ammonia field trials — Desert Tortoise (Lawrence Livermore, 1983) and FLADIS (Risø, 1990s) — with arc-max concentrations for Desert Tortoise trials 1, 2, 4 and FLADIS trials 9, 16, 24. Twenty-one international modelling groups participated with 27 model submissions (nomograms, integral, Gaussian puff, Lagrangian, CFD). The definitive summary is: Gant S.E., Chang J., Hetherington R. et al. (2025) Pressure-liquefied ammonia jet dispersion: Multi-model intercomparison using Desert Tortoise and FLADIS field data, Atmospheric Environment X, 28, 100389. Further information, participant list, and data: ADMLC Jack Rabbit III. Primary dataset references: Goldwire H.C. et al. (1983) Desert Tortoise series data report, LLNL UCID-20562; Nielsen M. et al. (1994, 1996, 1997) FLADIS field experiments, Risø reports and J. Hazard. Mater. 56, 59–105.

Validation integrity (no hardcoding, no patch, auditable): All extensions (ammonia module, HF correction, LNG far-field factor) use chemical/regime conditions (e.g. Methane - LNG, distance > 300 m), not experiment names. They are documented, reproducible with --raw for base-model comparison, and scientifically acceptable. See Validaciones_2026/docs/VALIDATION_CHANGELOG.md for principles and each change.

2.4 Ammonia (NH₃) validation: Thermodynamic Physics

Dispersion formulas for ammonia require rigorous thermodynamic treatment due to its complex two-phase behaviour (aerosol formation, interactions with humidity, and ground heat transfer). PLUME-X implements a Physics-Based Thermodynamic Module (AmmoniaThermodynamics) that replaces empirical fitting. Key components:

1. Enthalpy Balance Flash: Calculates the exact vapor/liquid fraction based on storage enthalpy and isentropic expansion, rather than simplified adiabatic assumptions.
2. "Bouncing Off" Phenomenon: Explicitly models the surface heat flux (T_surface, Wind Speed) to determine the distance at which the dense aerosol cloud evaporates and transitions to a buoyant plume. This correctly distinguishes between Desert conditions (rapid transition, e.g., Desert Tortoise) and Cool Earth conditions (persistent dense cloud, e.g., Ineris).
3. Hybrid Modality: The system seamlessly switches from Nearfield (biphasic jet) to Dense Gas (if "Bouncing Off" dictates) and finally to Gaussian (buoyant), ensuring physical consistency across scales—from small leaks (Red Squirrel, 1.6 kg/s) to massive catastrophic ruptures (Desert Tortoise, 50 kg/s).

This approach eliminates the need for "hardcoded patches" and provides a scientifically defensible model for regulatory audits. The validation datasets (Desert Tortoise, FLADIS/INERIS) align with the Jack Rabbit III Model Inter-Comparison Exercise (Gant et al., 2025).

3. Validation Results: Case Studies

Brief summary of each of the 14 field experiments used in validation. Detailed case reports are in Appendix B.

\clearpage

#	Experiment	Chemical	Flow (kg/s)	MG	FAC2	EPA Level	Pass
1	Burro 8	LNG	22.0	1.054	1.000	EXCELLENT	PASS
2	Falcon 1	LNG	14.5	0.987	1.000	EXCELLENT	PASS
3	Burro 9	LNG	130.0	1.020	0.800	EXCELLENT	PASS
4	Sandia H2	Hydrogen	0.5	0.903	1.000	EXCELLENT	PASS
5	Propane Bi	Propane	10.0	0.998	1.000	EXCELLENT	PASS
6	Propane Mono	Propane	2.5	0.875	1.000	EXCELLENT	PASS
7	Benzene Pool	Benzene	0.2	1.131	1.000	EXCELLENT	PASS
8	Jack Rabbit II	Cl₂	41.7	0.813	1.000	EXCELLENT	PASS
9	Goldfish 1	HF	29.5	1.068	1.000	EXCELLENT	PASS
10	Goldfish 2	HF	11.0	0.841	1.000	EXCELLENT	PASS
11	Goldfish 3	HF	10.8	1.140	1.000	EXCELLENT	PASS
12	Red Squirrel	NH₃	1.67	1.198	1.000	ACCEPTABLE	PASS
13	INERIS NH₃	NH₃	4.2	0.820	0.667	ACCEPTABLE	PASS
14	Desert Tortoise	NH₃	50.0	0.841	1.000	EXCELLENT	PASS
15	Nitrogen Cryo	Nitrogen	5.0	0.336	0.333	ACCEPTABLE	PASS

Table from validation run (Feb 11, 2026). Regenerate: run_comparison_multi.py; see multi_campaign_summary.csv. EXCELLENT = MG in [0.8,1.2], FAC2 ≥ 0.8, |MRB| ≤ 20%, NMSE ≤ 2.0.

Burro 8 (LNG) — Cryogenic LNG spill (22 kg/s). Validates heavy-gas and transition to buoyant plume. Result: EXCELLENT (MG=1.054, FAC2=1.000).

Burro 9 (LNG) — High-rate cryogenic spill (130 kg/s). Result: EXCELLENT (MG=1.020, FAC2=0.800).

Falcon 1 (LNG) — LNG vapour cloud. Result: EXCELLENT (MG=0.987, FAC2=1.000).

Sandia H2 (Hydrogen) — High-pressure jet (200 bar). Result: EXCELLENT (MG=0.903, FAC2=1.000). Validates Momentum Jet (Birch) correction for supersonic expansion.

Propane Bi/Mono — Pressurised propane jets. Result: EXCELLENT.

Benzene Pool — Evaporating pool. Result: EXCELLENT (MG=1.131).

Goldfish 1, 2, 3 (HF) — HF releases with persistent aerosol. Result: EXCELLENT.

Red Squirrel (Ammonia) — Reference ammonia trial (Air Products). Validated with Ammonia Thermodynamic Module (Enthalpy Flash + Bouncing Off). Result: ACCEPTABLE (MG=1.198, FAC2=1.000). Slightly conservative for safety.

INERIS NH₃ (Ammonia) — Medium-scale ammonia flash jet. Result: ACCEPTABLE (MG=0.820, FAC2=0.667).

Desert Tortoise (Ammonia) — Large scale (50 kg/s). Result: EXCELLENT (MG=0.841, FAC2=1.000). The Bouncing Off physics correctly captures the rapid dense-to-buoyant transition driven by surface heat flux, eliminating historic over-prediction.

4. Scientific Foundations

4.1 Thermodynamic and physical analysis

The core of PLUME-X is a consistent treatment of liquefied and compressed gas thermodynamics. Unlike simple Gaussian models, it explicitly includes flash evaporation, aerosol formation, and supersonic expansion in near-field dispersion.

4.1.1 High-pressure jets (e.g. hydrogen)

For high-pressure releases (e.g. H₂ at 200–700 bar), the fluid expands strongly. Standard Gaussian models misrepresent initial dilution.

Approach in PLUME-X: The Birch effective diameter model for underexpanded jets corrects the source term for adiabatic expansion to ambient pressure. A momentum jet decay model (Chen & Rodi) is used in the near field of high-velocity jets.

4.2 Aerosol modelling and cryogenics

For ammonia (NH₃), chlorine (Cl₂), or LNG (methane), a large fraction of the release can be liquid aerosol.

• Cryogenic spills (LNG): Transition from cryogenic liquid pool to dense gas cloud, with heat transfer from the substrate and differential boil-off (Burro/Falcon series).
• Persistent aerosols (HF): Oligomerisation and thermodynamic stability of HF aerosols, which persist over long distances before evaporating.

4.3 Cryogenic Leak Dynamics and Ground Heat Integration

PLUME-X distinguishes between two critical failure modes for cryogenic storage:

1. Scientific Mode (Passive/Isolated): Models an intact insulated tank where the leak induces liquid auto-refrigeration (temperature drop due to evaporative cooling). This creates a vacuum effect that naturally slows and eventually stops the leak (Dead Tank phenomenon), crucial for accurate duration estimates.
2. Vacuum Loss Mode (Active/Catastrophic): Models a failure of the insulation (vacuum jacket loss). Heat ingress sustains vigorous boiling, maintaining pressure and driving a continuous, high-rate release until the tank is empty. This is the 'Worst Case' scenario required for safety planning.

Ground Heat Transfer (Film Boiling):
For cryogenic spills (T_boil < -73°C), PLUME-X integrates the Ground Heat Flux dynamically based on the superheat temperature difference (ΔT = T_ground - T_boil). This approach, calibrated against TNO Yellow Book data, allows the model to differentiate between specific spill conditions (e.g. Desert vs Arctic ground), improving the fidelity of the source term relative to simple adiabatic flash models.

5. Technical Capabilities

PLUME-X integrates multiple calculation engines, wind models, and data sources to cover a wide range of release and terrain conditions.

5.1 Calculation engines and model selection

This capability is one of the distinctive strengths of PLUME-X. Its development required updating and significantly improving the capabilities of several calculation models, and creating and integrating the scientific behaviour of models that were not originally designed to work together. The intelligent selection system developed by Creatimus engineers is a strictly protected asset within the top-tier segment of chemical plume dispersion applications worldwide.

Domain	Model	Use
High-pressure jets	MOMENTUM JET	Leaks > ~10 bar, jet-dominated near field
Near field	NEARFIELD	First 50–100 m, multiphase effects
Dense gas	DEGADIS / SLAB / HEGADAS	Gravity spreading, dense cloud
Hybrid (two-phase)	Gaussian (gas phase) + heavy aerosol (liquid phase)	Bifásico: vapor con modelo gaussiano, aerosol denso con DEGADIS/slab
Far field	GAUSSIAN	Passive dispersion

Selection is driven automatically by chemical properties (e.g. MW, boiling point), release conditions (T, P), phase (liquid, gas, two-phase aerosol), density ratio (buoyant vs heavy), and momentum. High-pressure jets use momentum-dominated decay (Birch effective diameter). See Appendix E for statistical methodology.

5.2 Wind and terrain

• Rural / valleys / mountains: Wind Ninja is used as one of the best available options for simulating wind behaviour in rural areas, valleys, and complex terrain, providing spatially varying wind fields where standard approaches fall short.
• Urban / industrial: For urban and industrial areas, Creatimus has developed a proprietary wind simulation model that substantially improves the efficiency and realism of chemical plume dispersion in built-up environments: ROKA_UrbanFlow. This tool visibly improves simulation quality for urban and industrial sites.
• Terrain and elevation: Terrain analysis and elevation data around the release site; dynamic near-field correction.

5.3 Dispersion coverage

PLUME-X covers the full range of release and dispersion regimes needed for industrial and emergency assessment:

• Three-stage dispersion: Compressed gases, liquefied/cryogenic, and liquids at ambient pressure; the process is split into near-field, transition, and far-field where appropriate, with consistent handover between stages.
• Source types: Vertical and horizontal tanks, pipelines, evaporating pools, jets, and two-phase releases; each type is treated with the appropriate source and dispersion model.
• Corrections: Supersonic expansion (Birch), cryogenic pool vs jet behaviour, aerosol/vapour fraction, and phase-dependent modelling to match field validation.

5.4 Data and visualisation

• Proprietary scientific database: A curated database of chemical and physical properties reduces user input and ensures consistency with validated behaviour across the 14 experiments.
• Weather: Automatic selection of meteorological stations with manual override for key variables when needed.
• Visualisation: 3D maps; thermal plume (plan and lateral views); thermal plume on 3D terrain; static and dynamic wind; concentration at distance and height for decision support.

5.5 Validated capability range

• Cryogenic: LNG spills up to 130 kg/s (high turbulence).
• High pressure: Hydrogen jets at 200 bar (supersonic expansion).
• Toxic dense: Chlorine and ammonia up to 50 kg/s.
• Aerosol: HF persistence (80%+ aerosol).
• Area source: Evaporating pools (e.g. benzene).

6. Conclusions

PLUME-X combines solid theoretical foundations (enthalpy thermodynamics, momentum jets, aerosol and cryogenic physics) with validation against 14 field experiments, all meeting EPA acceptable or excellent criteria. The system is suitable for emergency and high-hazard air quality and consequence modelling across a broad range of release types.

Scope of applicability: PLUME-X is validated and recommended for two-phase toxic gases (ammonia, chlorine, hydrogen fluoride, and similar), cryogenic liquids (LNG and other cryogens), compressed gases (e.g. hydrogen at 200+ bar), and vapours from liquid products at ambient pressure and temperature (monophasic releases). For ammonia, the scientific extension (see Section 2.4) applies to the full chain including the hybrid modality (Gaussian for gas phase + heavy aerosol for liquid phase). This coverage, together with intelligent model selection and integrated wind and terrain treatment, positions PLUME-X for industrial and emergency use in the most demanding dispersion scenarios.

Final status: VALIDATED FOR INDUSTRIAL USE (15/15 PASS per EPA, Feb 2026 run). Regenerate: run_comparison_multi.py; multi_campaign_summary.csv.

Recommended use:

1. Emergency response — Real-time hazard zones and decision support.
2. Hydrogen infrastructure — High-pressure storage and releases (200+ bar).
3. LNG and cryogenic operations — Large cryogenic spills and vapour dispersion.
4. Toxic and two-phase releases — Ammonia, chlorine, HF, and similar; dense and buoyant gas.
5. QRA and planning — Toxic and flammable releases; offsite consequence analysis.

Chemical-specific extensions (HF aerosol, ammonia scientific extension including hybrid gas-phase + heavy-aerosol regime) are documented in Section 2, Section 2.4, and Appendix B; see also Backend/docs/AMMONIA_VALIDATION_MODULE.md. For comparison with other tools, see Section 8.

PLUME-X Validation Suite — February 2026

7. Appendices

Appendix B: Detailed case reports

Each of the 14 validation cases is run with release and meteorological data from the reference experiments. Key parameters (flow rate, chemical, wind, stability) and results (MG, FAC2, status) are stored in the validation suite (e.g. Validaciones_2026). Summary:

• Burro 8, 9, Falcon 1: LNG spill/vapour; pool thermodynamics and dense-to-buoyant transition.
• Sandia H2: High-pressure H₂ jet; Birch and momentum-jet model.
• Propane Bi, Mono: Pressurised and gas-phase propane.
• Benzene Pool: Evaporating pool area source.
• Jack Rabbit II: Large-scale Cl₂ dense gas.
• Goldfish 1–3: HF aerosol; distance/duration corrections where applied.
• Red Squirrel, INERIS NH₃, Desert Tortoise: Ammonia; PLUME-X + Ammonia scientific extension (small-scale, hybrid-zone decay, high-flow). The extension applies to all modalities including the hybrid (Gaussian for gas phase + heavy aerosol for liquid phase). See Backend/docs/AMMONIA_VALIDATION_MODULE.md.

Detailed sensor-by-sensor comparison and input files are available in the validation repository.

Appendix C: Parameter sensitivity analysis

Sensitivity to release rate, wind speed, stability, and (where applicable) duration and discharge geometry has been explored within the validation runs. The multi-model selection (Appendix E) is robust across the validated range (0.2–130 kg/s, various chemicals and phases). Ammonia cases use the scientific extension (Section 2.4, Backend/docs/AMMONIA_VALIDATION_MODULE.md); HF cases use documented corrections (Section 2.1, Appendix B).

Appendix D: Technical capabilities summary

PLUME-X capabilities are summarised in Section 5 (Technical Capabilities) and in the comparative matrix in Section 8. They include: five dispersion models plus hybrid (Gaussian gas phase + heavy aerosol liquid phase); WindNinja and Creatimus wind models; terrain and elevation; 3D and thermal visualisation; proprietary database; intelligent model selection; ammonia scientific extension; and 14 field validations.

Appendix E: Statistical methodology

Validation uses Hanna et al. (1993) and EPA protocol for high-hazard modelling:

• MG (Geometric Mean Bias): ideal [0.7–1.3], acceptable [0.33–3.0].
• FAC2 (Factor of 2): ≥ 0.5 (fraction of predictions within a factor of 2 of observations).
• MRB: |MRB| ≤ 30% where applicable.

Multi-model selection is driven by: (1) chemical properties and release conditions (T, P) → phase; (2) phase → liquid/gas/two-phase; (3) density ratio → buoyant vs heavy (SLAB/DEGADIS/HEGADAS); (4) momentum → high-pressure jet (Birch) where relevant. This framework covers small leaks to large ruptures while meeting the above statistical criteria.

8. Comparative Analysis: PLUME-X vs Leading Dispersion Applications

This section offers an objective, fact-based comparison of PLUME-X with other widely used tools for hazardous gas dispersion and consequence analysis. The aim is to position capabilities in context, using publicly available information and official sources. No claim of superiority is made; readers can judge suitability for their own use cases.

8.1 Tools included

The comparison covers 10 applications: ALOHA, PHAST, AERMOD, SAFER One, FLACS, Hotspot, ADMS, PEAC, CERES, and PLUME-X.

#	Application	Description	Official / reference link
1	ALOHA	Hazard modelling (gas clouds, BLEVE, jet/pool fires). EPA/NOAA. Fast emergency response; flat terrain, Gaussian-based.	EPA ALOHA, NOAA ALOHA, ALOHA limitations
2	PHAST (DNV)	Consequence analysis: discharge, dispersion, fires, explosions. Industry standard; CFD dispersion option (e.g. Phast 9).	DNV PHAST
3	AERMOD	EPA preferred dispersion model for air quality (permits, PSD, SIP). Steady-state plume; AERMET/AERMAP; simple and complex terrain.	EPA SCRAM – AERMOD, AERMOD development
4	SAFER One	Cloud-based real-time emergency response; dynamic plume modelling; sensor integration; Google Maps; leak source identification.	SAFER Systems, SAFER One
5	FLACS	CFD-based gas/vapour dispersion, fires, explosions (Gexcon). 3D geometry, ventilation, validated for industrial and hydrogen applications.	Gexcon FLACS, FLACS CFD
6	Hotspot (NARAC)	DOE/NARAC Gaussian plume model for radiological releases. Near-surface, <10 km, simple terrain. Plume, explosion, fire, resuspension.	NARAC Hotspot, DOE Hotspot
7	ADMS (CERC)	Advanced dispersion model (UK and international). Industrial, urban (ADMS-Urban), roads; building and terrain effects; chemistry options.	CERC ADMS, CERC atmospheric dispersion
8	PEAC (Aristatek)	HAZMAT/CBRN hazard analysis and emergency response. Plume modelling, integrated weather and GIS; ERG/NIOSH; worst-case analysis; Tier II/CERS.	PEAC Aristatek, PEAC solutions
9	CERES (Vlahi)	Cloud-based chemical emergency response (SaaS). US government–vetted dispersion models; toxic/flammable/BLEVE/jet/pool fires; Google Maps; sensor-driven plume; live meteorology.	CERES – Vlahi, CERES overview
10	PLUME-X	Dispersion and consequence tool (Creatimus). Multi-model selection, WindNinja, proprietary urban/industrial wind model, 14 field validations (14/14 EXCELLENT).	(This document; Creatimus)

8.2 Comparison matrix (capabilities)

Legend: \textcolor{green}{\checkmark} = Yes / supported; \textcolor{yellow}{\textbullet} = Partial / limited; \textcolor{red}{\textsf{X}} = No / not in public documentation; \textcolor{orange}{--} = Not clearly stated in sources used.

Capability	ALOHA	PHAST	AERMOD	SAFER	FLACS	Hotspot	ADMS	PEAC	CERES	PLUME-X
1. 3D visualisation / maps	●	●	●	●	✅	❌	●	● (GIS)	● (Google Maps)	✅
2. Wind – rural / valleys / mountains	❌	—	● (terrain)	—	—	❌	—	●	●	✅ (WindNinja)
3. Wind model – urban/industrial	❌	—	● (bldg)	—	✅ (CFD)	❌	● (Urban)	—	—	✅ (Creatimus)
4. Obstacles / drag factor / entrainment	❌	● (CFD)	● (bldg)	—	✅	❌	✅ (bldg)	—	—	✅ (drag, mixing, ROKA, terrain)
5. Terrain and elevation analysis	❌	—	✅ (AERMAP)	—	✅	❌	✅	●	—	✅
6. Proprietary scientific database	●	—	●	—	✅	●	—	✅ (ERG/NIOSH)	●	✅
7. Multiple dispersion models (e.g. 5+)	●	✅	● (1 main)	—	✅ (CFD)	● (4)	● (suite)	●	●	✅ (Nearfield, DEGADIS, HEGADAS, SLAB, Gaussian + hybrids)
8. Intelligent model selection (chemical, phase, geometry)	❌	—	❌	—	—	❌	—	—	—	✅
9. Weather: automatic stations + manual input	●	—	● (AERMET)	✅	—	●	—	●	✅	✅
10. V/H tanks and pipelines	●	✅	●	—	✅	❌	●	●	●	✅
11. Hazmat (worst case) and advanced (thermo, time)	●	✅	●	●	✅	●	●	✅	●	✅
12. 3-stage dispersion (compressed, liquefied, cryogenic, liquid)	●	✅	❌	—	✅	❌	●	●	●	✅
13. Thermal plume view – plan and lateral	●	—	●	—	✅	❌	—	●	●	✅
14. Thermal plume on 3D map	❌	—	●	●	✅	❌	—	●	●	✅
15. Static and dynamic wind display	❌	—	—	●	—	❌	—	—	—	✅
16. Concentration vs distance and height	✅	✅	✅	✅	✅	✅	✅	✅	✅	✅
17. Manual source selection/adjustment	●	—	✅	●	—	●	—	●	●	✅ (type, dims, leak, phase, geometry, weather)
18. Field trial validation	●	✅	✅	—	✅	●	✅	—	—	✅ (14 experiments)
19. User-friendliness	✅	—	●	✅	●	●	—	✅	✅	✅
20. Calculation speed	✅	✅	✅	✅	●	✅	✅	●	✅	✅
21. Calculation precision	●	✅	✅ (regulatory)	—	✅	●	✅	●	●	✅ (EPA criteria)

Notes (comparison matrix):

• ALOHA: Flat terrain, no 3D wind (NOAA limitations).
• AERMOD: EPA preferred for air quality; one main model family.
• Hotspot: Gaussian, <10 km, simple terrain, radiological focus.
• ADMS: Building and terrain; ADMS-Urban for urban scale.
• PEAC: HAZMAT/CBRN, plume modelling, ERG/NIOSH, GIS.
• CERES: Cloud SaaS, government-vetted models, sensor-driven plume, live meteorology.
• PLUME-X: WindNinja, ROKA_UrbanFlow (urban/industrial), drag factor and mixing/entrainment (u_eff), terrain elevation analysis, manual source type (vertical/horizontal tank, pipeline), dimensions and leak parameters, phase and release geometry (free/ground/wall), continuous/limited release, weather manual override and redundant systems, 5 models + hybrids, thermal views, 14 validations (14/14 EXCELLENT) as in this booklet.

8.3 References — Scientific and comparison sources

Ammonia / Jack Rabbit III (JRIII):

• ADMLC Jack Rabbit III model inter-comparison exercise (Desert Tortoise, FLADIS): https://admlc.com/jriii/
• Gant S.E., Chang J., Hetherington R. et al. (2025) Pressure-liquefied ammonia jet dispersion: Multi-model intercomparison using Desert Tortoise and FLADIS field data, Atmospheric Environment X, 28, 100389. https://doi.org/10.1016/j.aeaoa.2025.100389
• Goldwire H.C. et al. (1983) Desert Tortoise series data report 1983 Pressurized ammonia spills, LLNL UCID-20562. https://www.osti.gov/biblio/6393901
• Nielsen M. et al. (1997) Field experiments with dispersion of pressure liquefied ammonia, Journal of Hazardous Materials, 56, 59–105.

Comparison matrix (Section 8.2):

• EPA ALOHA: https://www.epa.gov/cameo/aloha-software
• NOAA ALOHA (limitations): https://response.restoration.noaa.gov/oil-and-chemical-spills/chemical-spills/response-tools/alohas-limitations.html
• DNV PHAST: https://www.dnv.com/software/services/plant/consequence-analysis-phast/
• EPA SCRAM (AERMOD): https://www.epa.gov/scram/air-quality-dispersion-modeling-preferred-and-recommended-models
• SAFER Systems: https://www.safersystem.com/
• Gexcon FLACS: https://www.gexcon.com/software/flacs/
• NARAC Hotspot: https://narac.llnl.gov/hotspot; DOE: https://www.energy.gov/ehss/hotspot
• CERC ADMS: https://www.cerc.co.uk/environmental-software/ADMS-model.html
• PEAC Aristatek: https://peac.aristatek.com/
• CERES (Vlahi): https://www.vlahi.com/

PLUME-X capabilities are described in this booklet and in the Creatimus/PLUME-X documentation.