Open-source probabilistic risk assessment

The set of triplets — Kaplan & Garrick, 1981. The completeness subscript c is Kaplan's later refinement, 1997.

Risk, in the open.

Risk is a set of triplets: what can go wrong, how likely it is, and what the consequences are if it does. OpenPRA is where you build that set — schema, engines, workbooks, and reference models, all readable by anyone.

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s — scenario

What can go wrong?

Kaplan and Garrick define s as the identification or description of a scenario. Operating states, initiators, event sequences, success criteria, and system logic — built in a workbook and stored as schema, not as a file nobody else can open.

POS · IE · ES · SC · SY

p — probability

How likely is it that that will happen?

p is the probability of that scenario — and probability here is a measure of a state of knowledge, distinct from frequency, which is what a repeated experiment would yield. The model carries both, and the uncertainty with them, and PRAXIS solves it.

HR · DA · ESQ

x — consequence

If it does happen, what are the consequences?

x is the consequence or evaluation measure of that scenario — the measure of damage. Mechanistic source term, offsite dose and health effects, and integration to plant risk — all built, which means the platform produces the metrics the standard actually uses rather than a surrogate.

MS · RC · RI

Those three hues carry through the platform, the documentation, and every chart on this site. A probability is never orange; a consequence is never teal.

Coverage

The technical elements of the standard

ANSI/ASME/ANS RA-S-1.4-2021 defines eighteen technical elements, from operating states through to risk integration. It is an integrated standard: there is no split into levels, because that split does not apply to every advanced reactor design. OpenPRA implements the elements that apply across all hazard groups, plus seismic — initiating events through to integrated risk, in one schema, so the model stays one object rather than a folder of exports.

One format, and it is documented

The OpenPRA MEF is defined in TypeScript and published as JSON Schema. Models move between tools without a bespoke converter, and a reviewer can read the definition rather than infer it from a file.

Read about the schema

Free, and it stays that way

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Everything is open source. There is no paid tier, no enterprise edition, and no plan for one.

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