Support

Questions, bug reports, wrong numbers, and feature requests all go to the same place. No account needed.

[email protected] · usually answered within a few days.

Reporting a number you think is wrong? Please include the isotope or material, every input you entered with its units, the value the app showed, and the value you expected with its source. That turns a report into something reproducible, and accuracy reports get looked at first.

Common questions

OFFLINE: Every calculator works with no network connection. All reference data ships inside the app — nothing is fetched while you use it.
ACCOUNTS: There are none. No sign-up, no login, no password to lose.
COST: Every calculator is free and unrestricted, in the apps and on this website. In the iOS and Android apps, Nuclear Toolkit Pro (US$2.99 a month or US$14.99 a year; local prices vary by store region) adds calculation records — numbered PDF and CSV exports carrying the preparer, reviewer, notes and the data versions used, with a searchable history on your device. Manage or cancel it in your App Store or Google Play subscription settings. The website has no subscription.
UNITS: Switch between SI and US customary from the settings control — becquerels or curies, sieverts or rem. It changes display only, never the underlying maths.
BROWSER: The version on this site is the same codebase as the mobile apps. The mobile builds are smoother for gestures such as pinch-zooming the chart of nuclides.

Where the numbers come from

Every dataset in the app is published by a public scientific authority, and every screen cites its source and the textbook section its formulas come from.

NUCLIDES: IAEA Live Chart of Nuclides — 3,383 ground states from the NUBASE2020 and AME2020 evaluations.
GAMMA LINES: IAEA decay radiation data (ENSDF) — emission energies and intensities.
SHIELDING: NIST Standard Reference Database 126 — photon mass attenuation and energy-absorption coefficients (Hubbell & Seltzer).
DENSITIES: PubChem, National Center for Biotechnology Information (NCBI/NIH).
FORMULAS: Lamarsh & Baratta, Introduction to Nuclear Engineering; Duderstadt & Hamilton, Nuclear Reactor Analysis; ICRP Publications 74 and 103.

The validation page lists every check of the app’s results against published values — handbook gamma constants, specific activities, textbook identities and independent calculations — with the deviation and tolerance of each, and the errors earlier audits found and fixed.

A note on scope. This is a reference and calculation tool for people who already work in the field. It is not a medical device, and it does not read from or control instruments. Results do not replace analysis by a qualified health physicist or nuclear engineer. The Terms of Service has the full statement.