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NUCLEAR ENGINEERING · HEALTH PHYSICS

Decay, dose and shielding. Every number sourced.

Eleven calculators built on the IAEA chart of nuclides and the NIST attenuation tables. Every screen cites the dataset it used and the textbook section behind the formula.

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Free · no account · works offline · iOS app in review

NUCLIDES
3,383IAEA NUBASE2020 / AME2020
GAMMA EMITTERS
120Line spectra from ENSDF
SHIELD MATERIALS
9NIST μ/ρ and μen/ρ
NETWORK CALLS
0The data ships in the app
Chart of nuclides coloured by decay mode
Chart of nuclides
Gamma dose rate and shielding calculator
Dose & shielding
Decay chain activity plotted against time
Decay chains
Xenon-135 poisoning transient after reactor shutdown
Xe-135 transients

Eleven tools

⚛︎Chart of Nuclides

All 3,383 ground states, coloured by decay mode. Pan, zoom, filter by half-life. Tap any nuclide for its branches, spin-parity and decay chain.

AtDecay Calculator

A(t) = A₀e−λt for any isotope, or enter your own half-life. Works forward from a calibration date and backward to one.

γDose & Shielding

Point-source dose rate summed over the real emission spectrum, with Taylor buildup, half- and tenth-value layers, and ALARA stay time. Also solves for distance or thickness.

σMDA / Counting

Currie critical level and detection limit. Minimum detectable activity and concentration, plus a gross-count detection decision.

XeXe-135 Simulator

Xenon transients for shutdown, startup and step changes. Gives the reactivity worth and the time the iodine pit peaks.

k∞Formula Explorer

Six-factor formula and point kinetics on live sliders. Shows k_eff, prompt-jump reactivity, stable period and dollars.

⇆Unit Converter

Activity, absorbed dose, dose equivalent, dose rate, energy and exposure. Includes the ICRP 103 weighting factors.

ρMixture & Enrichment

Parses chemical formulas, converts weight and mole fractions, breaks down composition by element, and runs a cascade mass balance with SWU.

ΣDecay Chain

Full Bateman solution across a chain. Classifies equilibrium, plots activity against time, exports CSV.

μPhoton Transmission

Transmission against thickness for nine materials across the NIST energy grid, with buildup on or off.

n°Neutron Activation

Activation product build-up and decay under a chosen flux, with saturation activity and presets for common facilities.

Where the numbers come from

Nothing here is typed in by hand. Every dataset is pulled from its publisher's API by a script, and named on the screen that uses it.

IAEANUBASE2020 / AME2020
Live Chart of Nuclides. Half-lives, decay modes and branching ratios, spin-parity, atomic masses, natural abundance.
IAEAENSDF / decay_rads
Gamma emission energies and intensities for 120 emitters, including secular-equilibrium progeny variants.
NISTSRD 126
Photon mass attenuation and mass energy-absorption coefficients (Hubbell & Seltzer) for nine materials.
PubChemNCBI / NIH
Elemental densities, used for rule-of-mixtures composition and shield mass.
Textbookscited on screen
Lamarsh & Baratta, Introduction to Nuclear Engineering. Duderstadt & Hamilton, Nuclear Reactor Analysis. ICRP Publications 74 and 103.
Scope. This is a reference and calculation tool for people who already work in the field. It is not a medical device, and it is not certified for operational, safety-critical or regulatory use. Results do not replace analysis by a qualified health physicist or nuclear engineer. See the Terms of Service.