Universal Decay Calculator

(last updated 7 Feb 2026)
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For optional graphical output, the browser must be HTML 5-capable.
For educational purposes only. No warranty.
The decay and air kerma data is taken from ICRP-07 Data Files © A. Endo and K.F. Eckerman 2008.

Calculate radioactive decay of 1252 nuclides, including ingrowth and decay of their progeny, and show point-source air kerma.

Enter the parameters and click the "Calculate" button below. HELP

Numbers can be entered in exponential notation: 5.1 · 10^-6 = 5.1e-6
"t" means metric tonne.

------- select Mass Unit or Sample Data, or enter Initial Activities below ------- **** Select Mass Unit ************* g of nominal nuclide of each series below kg of nominal nuclide of each series below t of nominal nuclide of each series below **** Select Sample Data ********** g U(nat) pure g U(nat) equil. g Th(nat) pure g Th(nat) equil. t uranium ore (grade 0.1% U) t uranium mill tailings (from ore grade 0.1% U at 90% extraction) g U(nat-enr) (3.5 wt-% U-235) g U(nat-dep) (0.2 wt-% U-235) Heels in [...] 48Y cylinder(s) formerly holding 12,500 kg UF6(nat) Heels in [...] 30B cylinder(s) formerly holding 2,277 kg UF6(nat-enr) (3.5wt-% U-235) g U(rep) (init. enr. 3.5%, 39 GWd/t, 5 y delay) g U(rep-enr) (init. enr. 3.5%, 39 GWd/t, 5 y delay) g U(rep-dep) (0.2 wt-% U-235, init. enr. 3.5%, 39 GWd/t, 5 y delay) tHM spent fuel (33 GWd/t, at unload) tHM spent fuel (33 GWd/t, 5 y after unload) HLW from reproc. of [...] tHM spent fuel (33 GWd/t, reproc. 5 y after unload) g Th-232 pure: Thorium series (4n) g Pu-241 pure: Neptunium series (4n+1) g U-238 pure: Uranium series (4n+2) g U-235 pure: Actinium series (4n+3) Bq Ra-226 pure: Secular equilibrium with short-lived progeny Bq Pb-212 pure: Transient equilibrium with slightly shorter-lived progeny Bq Bi-211 pure: No equilibrium with longer-lived progeny     Nuclide Input

+ with short-lived progeny       ++ with all progeny in secular equilibrium       ind.: individual progeny specification

 

Output Parameters
Time	Chart Type	Chart Data	Chart Detail	Chart Axes
Chart     Start *: End  : List **     Mark list time in chart	no chart line chart stacked areas animated bars	activities decay heat air kerma air kerma point source distance [m]	total values of each series all individual nuclide values individual nuclide values       for selected series: **** show total for selection *** skip minor nuclides	log. Y axis ***      Decades on      log. Y axis:       log. time axis/      time steps

* log. time axis only       ** or by mouse click       *** line chart only       **** multiple selections with CTRL-key
 
        HELP

Results

 

Click in chart to change List Time   ·   Click legend items to toggle specific curves on/off

 

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