What the platform covers
A PRA is not one artefact. It is eighteen analyses that have to agree with each other. OpenPRA holds them in one schema so they can.
Element names and codes follow ANSI/ASME/ANS RA-S-1.4-2021, endorsed by the NRC in Trial Regulatory Guide 1.247. The standard is technology-inclusive and integrated: it runs from initiating events to offsite consequence without splitting into levels, and it does not use core damage frequency or large early release frequency, which do not apply to many advanced designs.
From operating states to integrated risk
Initiating events through to risk integration are built. That means the chain runs all the way to offsite dose and health effects — the metrics the standard uses — rather than stopping at a surrogate and leaving the consequence side to another tool.
Plant operating state analysis
The states the plant can be in — power, shutdown, transition — each carrying its own initiators and success criteria.
in progressInitiating event analysis
Initiator identification, grouping, and frequency, carried through to the event sequence model.
implementedEvent sequence analysis
Event sequences with linked functional and systemic branches, end states, and transfer logic — including sequences with no consequence, which the licensing case needs.
implementedSuccess criteria development
Criteria per sequence and per system, with the supporting calculation recorded alongside.
implementedSystems analysis
Fault trees, common cause groups, and system notebooks tied to the components they model.
implementedHuman reliability analysis
THERP, IDHEAS, and NUREG-1792 method modules with their inputs kept in the model, not the analyst's head.
implementedData analysis
Parameter estimation with distributions and sources attached to every basic event.
implementedEvent sequence quantification
Solving the model as written rather than truncating until it is tractable. PRAXIS is the default solver; SCRAM remains as the reference implementation.
implementedMechanistic source term analysis
Release categories derived from the physics of the sequence rather than from a surrogate metric.
implementedRadiological consequence analysis
Offsite dose and health effects — the metrics RA-S-1.4 actually uses, since core damage frequency and large early release frequency do not apply to many advanced designs.
implementedRisk integration
Radionuclide sources, operating states, and hazard groups assembled into integrated plant risk, with risk significance applied to the result.
implementedSeismic first, the rest to follow
Seismic hazard, fragility, and plant response share the schema with the internal-events model rather than living in a parallel study. The other hazard-group elements are defined in the standard and not yet built.
Hazards screening analysis
Screening the hazard groups in or out, with the basis recorded.
plannedSeismic PRA
Hazard, fragility, and plant response — schemas named SHA, SFR, and SPR after the LWR standard's designators — with a worked HTGR example in the workbook.
implementedInternal fire PRA
Not yet implemented.
plannedInternal flood PRA
Not yet implemented.
plannedHigh winds PRA
Not yet implemented.
plannedExternal flooding PRA
Not yet implemented.
plannedOther hazards PRA
Not yet implemented.
plannedSolve the model, don't truncate it
Most tools reach a truncation limit and stop, then report a number
that depends on where they stopped. The engines here are built to
solve the model as written, and to say plainly when they cannot.
That is the ESQ element doing its job.
PRAXIS — the PRA eXecution and Insight System — is the default solver. It is written in Rust, works on propositional directed acyclic graphs, builds with or without CUDA, and reads the OpenPRA MEF directly rather than through a converter. The platform calls it over NAPI-RS bindings, so one binary serves the web workbooks and the command line alike.
SCRAM came first and is still maintained. It stays in the tree as the reference the newer solver is checked against, which is the only good reason to carry a second engine.
Quantification runs are distributed through a job broker, so a model that takes hours on a laptop takes minutes on a cluster without changing anything about the model.
Nothing is promoted on a claim. PRAXIS carries a release gate and a milestone promotion gate: converted real-model parity against the seven MHTGR OpenPSA models, run as exact CUDA Monte Carlo matching with no tolerance, blocks promotion on failure. The rollback procedure for every milestone is written down before it is needed.
Benchmarks against reference solutions live in the repositories alongside the models, not in a marketing table. Where a result disagrees with SAPHIRE, the disagreement is written down.
The packages
One monorepo, plus a few satellites. If you want to understand the
codebase, start with shared-types and follow it outward.
PRA eXecution and Insight System. The default solver — Rust, PDAG-based, with optional CUDA acceleration. Reads the OpenPRA MEF directly and exposes itself to the platform through NAPI-RS bindings.
The original quantification engine, still maintained and still the reference the newer solvers are checked against.
Monte Carlo quantification of Boolean logic on hardware-accelerated platforms, developed in its own repository.
Pure TypeScript definitions. The single source of truth for every domain type and DTO.
The OpenPRA MEF, generated as JSON Schema from shared-types.
React and TypeScript workbooks — the interface analysts actually use.
RabbitMQ job broker that scales quantification across workers.
Synthetic and design-derived model construction.
Format translation, including a SAPHIRE round trip through PRAXIS.
Deployments
Where it runs
The public site runs at openpra.org. Use the current application and documentation deployments below; the original application remains available as the legacy deployment.
| Role | Deployment | What it is |
|---|---|---|
| App | revamp-dev.openpra.org | The current OpenPRA application. |
| Docs | revamp-docs-dev.openpra.org | The current user and developer documentation. |
| Legacy | app.openpra.org | The original OpenPRA application. |