ACTINV

Inventory after irradiation

Give ACTINV a material, a particle-flux spectrum, an irradiation and cooling schedule, and evaluated nuclear data. It calculates which nuclides are created, how their populations change, and the resulting activity, decay heat, photon source, and selected radiological responses.

ACTINV is an inventory solver, not a transport-code extension. It accepts a spectrum directly and includes strict importers for documented OpenMC, MCNP, and FISPACT outputs. Every calculation records the exact inputs it used and keeps missing or unsupported information visible in a ledger.

Get started

The complete source, examples, controls, and validation evidence are public. The repository README begins with installation and a first calculation, then links to the specification and data setup.

What v1.0 includes

1. Data pipeline.ACTINV builds deterministic activation libraries from supported ENDF-6 evaluations, including TENDL-2025 neutron, proton, deuteron, and alpha data and EAF-2010 neutron data. Raw and generated bulk nuclear data remain outside the software repository.
2. Inventory evolution.CRAM-16/48 integration handles irradiation, cooling, and arbitrary pulse histories. ACTINV selects trace or coupled burn-up behavior from the recorded exposure and bounds what its pruning removes.
3. Useful outputs.Results can include inventories, activity, alpha/beta/gamma heat, photon lines and groups, production pathways, tritium and helium, user-supplied radiological responses, and cross-section uncertainty bands.
4. Transport workflows.OpenMC statepoints, MCNP MESHTAL/MCTAL, and FISPACT flux files feed a canonical spectrum format. Independent mesh cells run in parallel, and decay-photon sources export to OpenMC or MCNP.
5. One checked core.The command line, Python API, prepared calculations, and mesh calculations share the same Rust solver and are tested for scientific identity.

Validation carried with the code

ACTINV ships its controls and compact evidence alongside the implementation. The final v1.0 phase closed with all six gates passing, including a clean-clone package build and a successful public-runner control suite.

Validation establishes behavior for the recorded models, inputs, and acceptance bounds. It does not establish that a user’s material, spectrum, nuclear-data choice, radiological table, or regulatory scenario is suitable.

Designed to remain inspectable

1. Inputs stay attributable.Nuclear data are not bundled; files and generated libraries are identified by SHA-256 in each calculation’s certificate.
2. Incomplete information stays visible.Missing data, leakage, pruning, response coverage, and numerical dispositions appear in the result ledger.
3. Controls precede claims.Development gates are frozen before evidence, checker-derived verdicts are committed, and repair records remain append-only.
4. Boundaries are explicit.Uncertainty coverage, importer subsets, model assumptions, and responsibilities outside ACTINV are documented rather than implied.

Released and published

ACTINV v1.0.0 completed its repository release on 27 August 2026. The final P12 verdict is P12-CONDITIONAL: all six gates pass, while the word “conditional” preserves the documented repair amendments in the append-only development record.

The current release is v1.0.1, a backward-compatible performance patch: prepared activation data is cached deterministically and reused, cutting warm-path time and peak memory on the frozen public benchmark while leaving physics, schemas, inventories, and ledgers unchanged. Git tags, GitHub Release assets, PyPI, and crates.io publication are all live.

ACTINV is research-grade calculation software. It is not approved for licensing, safety, waste classification, or regulatory use. An organization placing it in a controlled analysis chain remains responsible for input qualification, applicability, independent review, uncertainty and margins, configuration control, and approval.

Documentation