FRI3D 1.2.0 Release Notes
Released: August 30, 2026
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Highlights
- Validated against NUREG-1934 — FDS and CFAST deck generation checked against the NRC reference decks (Appendix A CFAST, Appendix B FDS). The validation models ship with this release.
- Equipment beside a fire now fails when it should — CFAST probes sat half an item-size away from their item. They now sit on it, and failure times move in both directions.
- Large models are workable again — zone and scenario switching and zone deletion take seconds, not minutes, without the crashes.
- Long FDS runs finish — no longer stopped at fifteen minutes by a false idle check.
- Use FDS and CFAST results you already have — a scenario finds results sitting in the usual place on its own, or you can point it at any folder, without re-running the solver.
- Work with whole categories at once — select, hide, show, wireframe, and solid, with multi-select.
- Fire sources fail equipment directly — a failed raceway fails the cables it carries.
- Signed installer and a real About dialog — reports the FRI3D version alongside bundled CFAST, FDS, OpenCASCADE, OpenVDB, and IFC versions.
What's new
- Category operations in the model tree, with multi-select.
- Fire source to equipment failure coupling, including cables on a failed raceway.
- Sodium pool fire presets in the liquid fuel library.
- Liquid pool fires run in 3D CFD — previously Zone models only.
- FLASH-CAT cable properties: Plastic Mass Fraction and Heat of Combustion.
- Per-tray Cable Fill; fire elevation follows the burning trays.
- PLANTX import from an Access database.
- 3D CFD import: sources, vents (mechanical, static, holes), and the zone boundary.
- RiskSpectrum output without a simulation run, and relative PRA model paths.
- Visualization Override on a scenario: visualize 3d CFD or Zone model results from a folder you choose.
- Scenarios find results already sitting in the usual place, with no run and no setup.
- About dialog: version, licensee, and bundled solver and library versions.
Improvements and fixes
Simulation accuracy
- FDS mesh encloses the full wall envelope.
- Compartment leakage works; sealed compartments no longer over-pressurize.
- Vent flow direction follows the vent's orientation in both solvers.
- Duct enclosures default to sheet steel, not perfect insulation.
- Leak ratios are used exactly as entered, including zero.
- Walls and slabs are at least one cell thick, fixing FDS aborts with zone boundaries.
- Corrected vent directions, conductivity, and emissivity in FDS input.
- CFAST probes sit on the item they represent.
- With several fires, a target is measured against the nearest one and faces it.
- A nudged fire source is named, with its offset, in the run's model checks.
- Item extents refresh before save, so solvers get the real size and place.
- A pool fire's burning area adds up across every object it sits on.
PRA and RiskSpectrum
- RiskSpectrum output no longer needs a simulation run.
- PRA preferences no longer overwrite the base initiating event; affected projects are repaired on first open.
- Changing the PRA model clears the stored base case and initiating event.
- PRA paths resolve against the startup, project, or working folder; failures name the folders searched.
Performance and stability
- Much faster zone and scenario switching and zone deletion on large models.
- Rendering a movie from an FDS scenario no longer runs out of memory, and playback of FDS results is far faster.
- Smoke and temperature now follow the timeline instead of holding the frame they loaded on.
- Fixed crashes when opening several models in succession and when switching zones.
- Items with no assigned location stay in their scenarios.
- Fixed double selection of a category and then an item.
- Runs on Intel integrated graphics.
- Duplicating a fire source, or a detection or suppression item, now produces the copy.
- Duplicated equipment appears beside the original at the right position and size.
- A duplicated Physical Only item keeps its Building Item Type, and changing that type re-files it at once.
- The Zone Inspector 3D icon updates after a paste.
Floor plans
- A floor plan saved with a relative path is found again — looked up beside the application, in the preferences folder, and in the scene's own sub-folder. A missing file reports one clear message naming the places tried, instead of repeated decode errors.
- PDF floor plans render through a new PDF engine.
Simulation runs
- FDS progress is reported once per step, with the radiation-loss figure.
- The FDS progress dialog is now a dashboard: heat release rate, radiation loss, the solver's step size and pressure iterations on one row, and CFL, VN and the velocity and pressure errors on another, each with its units and a meter showing how close it is to its limit. Step size is worth watching — it falls when a run is struggling.
- Fixed readings in that dialog: the field labelled "Max Vel" showed a different quantity entirely and never moved off 0.00; CFL and VN read 0 because they were rounded to two decimals when they routinely run far smaller; and radiation loss, the run's end time and the two solver errors were being read from the solver and then discarded rather than shown.
- A failed FDS run closes its dialog, honours Cancel, and reports the real cause.
- CFAST falls back to default solver settings, with a warning, on older projects.
- Far less noisy logs.
Changes that affect existing models
Results change in this release. Re-run affected scenarios rather than comparing against 1.1.0 output.
- FDS meshes are larger — cell counts and run times rise on any model with walls.
- Duct enclosures conduct heat — sheet steel by default, matching the NRC decks.
- Vent flow direction may change — orientation now wins over From/To. Check mechanical ventilation on older models.
- "Fuel Loading" is now "Cable Fill" — tray cost fields are hidden.
- CFAST failure times change — times shift both ways, and items that never failed may now fail. On the Appendix B model, one extra cabinet fails and six times shift a few seconds later. Compartment results are unchanged.
- Leak ratios are honored exactly — zero means sealed. Zones left at zero on both wall and floor are updated on first open to standard values; a deliberate zero alongside a value you set is kept. New zones start at the standard values.
- Item extents recalculate on save — open and re-save any model built before 1.2.0, then re-run. The correction happens on save, not on open, and compounds with change 5.
- A fire spanning several objects burns over its full area in FDS — results change where a source overlaps two or more objects.