Changes to the calculators and data

This page records what changed from one version of RadCalc to the next, with anything that moves a calculated value listed before changes of wording. The version number moves in its middle place when a calculated value or the data change, as from 1.0 to 1.1, and in its last place when only the wording does, as from 1.1.0 to 1.1.1. The current version is 1.1.1 of 29 October 2026; every page shows it above the footer. Released versions are archived on Zenodo, where the concept DOI 10.5281/zenodo.22794265 always resolves to the newest.

1.1.1 — 29 October 2026

No calculated value changes in this version; it corrects what some pages display. The air kerma rate constant shown in the nuclide list, in the gamma calculator's results and on several reference pages was read from a stored copy rounded to six decimal places, so the smallest constants kept fewer than two significant figures and could differ from their own sheet: it showed 1.00e-6 for Pm-147, whose sheet gives 5.19e-7. Those places now show the value each sheet computes from its emission lines. The dose rates, thicknesses and activities the calculators work out were already computed from the lines and do not change.

1.1.0 — 29 October 2026

Calculated values change in this version. If you kept a figure from 1.0.1: the air kerma rate constants in the first table below, and every dose rate computed from them, are now lower by the amounts shown — most for Tl-201, by 14.6% — and their lead half-value layers shift, most on the sheets for In-111, by 31%. Cs-137 moves by −0.26% and Co-60 not at all. A conversion of Bq/L or pCi/L to a per-mass unit was off by a factor of a thousand, and a scan detection limit read six thousand times too high in the unit shown; both are set out below. Beta ranges and bremsstrahlung fractions now appear for 27 nuclides that had none, and the sheets of 75 nuclides were withdrawn.

K-beta X-rays were counted twice

For many nuclides the photon lines harvested from the IAEA Livechart carried the total K-beta X-ray line alongside the K′β1 and K′β2 lines it is made of, so the same photons entered every sum twice. The total line — or, where the second component fell below the listing threshold, the one component recorded beside it — has been removed: 79 lines across 70 nuclides. The air kerma rate constant Γ, the dose rates, and the half- and tenth-value layers worked out from those lines changed for 57 nuclides. On the nuclide sheets the constant moved by one per cent or more for these:

Nuclide	Γ before	Γ now	Change
Tl-201	0.01236	0.01056	−14.56%
I-125	0.04000	0.03501	−12.48%
Cd-109	0.04518	0.03972	−12.09%
Xe-133	0.01401	0.01258	−10.19%
Sm-153	0.01192	0.01073	−10.00%
Ra-223	0.01705	0.01585	−7.04%
Ce-139	0.03093	0.02884	−6.77%
In-111	0.08067	0.07663	−5.01%
Ba-133	0.07328	0.06985	−4.68%
Tc-99m	0.01530	0.01474	−3.68%
Pu-239	0.000008233	0.000007983	−3.04%
Lu-177	0.004201	0.004103	−2.32%
Ra-226	0.0008785	0.0008635	−1.71%
U-235	0.01944	0.01918	−1.37%
Mo-99	0.01937	0.01913	−1.28%
Re-188	0.007616	0.007526	−1.18%
Eu-152	0.1523	0.1507	−1.03%

Γ in mGy·m²/(GBq·h), δ = 20 keV, as on the sheets.

Where the removed line was softer than the gamma lines that remain, its loss hardens the spectrum and the lead half-value layer grows — on the sheets most for In-111, by 31%. Where it was the harder of the K X-rays, as for I-125, Cd-109 and Tl-201, the half-value layer shrinks, by 2.7 to 3.4%.

Nuclide	Lead HVL before (mm)	Now (mm)	Change
In-111	0.158	0.208	+31.1%
Ba-133	0.582	0.703	+20.9%
Ra-223	0.541	0.628	+16.1%
Ce-139	0.0846	0.0947	+12.0%
Tc-99m	0.229	0.243	+6.1%

Across the whole dataset the largest change is for Sn-113, which has no sheet: its lead half-value layer goes from 0.0684 to 0.206 mm, and its tenth-value layer from 84 half-value layers to 29 — the ratio quoted in the description of 1.0.1.

All 57 nuclides whose Γ or lead half-value layer changed

Nuclide	Γ before	Γ now	Change	Lead HVL before → now (mm)
Tl-201	0.01236	0.01056	−14.56%	0.224 → 0.218
Ir-192m2	0.00008187	0.00007040	−14.01%	0.189 → 0.185
I-125	0.04000	0.03501	−12.48%	0.0176 → 0.0170
Sn-113m	0.01728	0.01513	−12.43%	0.0137 → 0.0133
Cd-109	0.04518	0.03972	−12.09%	0.00999 → 0.00966
Cd-109m1	0.01925	0.01698	−11.76%	0.0117 → 0.0114
Re-188m	0.009874	0.008809	−10.78%	0.138 → 0.133
Cs-134m	0.008799	0.007859	−10.68%	0.0315 → 0.0316
Xe-133	0.01401	0.01258	−10.19%	0.0342 → 0.0346
Xe-133m	0.01245	0.01119	−10.09%	0.0324 → 0.0331
Sm-153	0.01192	0.01073	−10.00%	0.0673 → 0.0673
Ba-133m	0.01779	0.01625	−8.69%	0.0547 → 0.0590
Ra-223	0.01705	0.01585	−7.04%	0.541 → 0.628
Ce-139	0.03093	0.02884	−6.77%	0.0846 → 0.0947
Sn-113	0.07059	0.06619	−6.23%	0.0684 → 0.206
Ce-144	0.003344	0.003137	−6.20%	0.0859 → 0.0913
In-111	0.08067	0.07663	−5.01%	0.158 → 0.208
Ta-182m2	0.03391	0.03223	−4.95%	0.297 → 0.310
Ba-133	0.07328	0.06985	−4.68%	0.582 → 0.703
Eu-152m2	0.009956	0.009495	−4.63%	0.0718 → 0.0721
Eu-154m	0.01341	0.01283	−4.31%	0.0638 → 0.0636
Ce-141	0.01089	0.01049	−3.70%	0.165 → 0.177
Tc-99m	0.01530	0.01474	−3.68%	0.229 → 0.243
Pu-239	0.000008233	0.000007983	−3.04%	0.120 → 0.120
Au-198m	0.06472	0.06313	−2.46%	0.481 → 0.493
Sb-125	0.07016	0.06849	−2.38%	2.52 → 2.65
Lu-177	0.004201	0.004103	−2.32%	0.391 → 0.404
Lu-177m	0.1312	0.1289	−1.81%	0.926 → 0.961
Ra-226	0.0008785	0.0008635	−1.71%	0.473 → 0.485
Sm-153m	0.01042	0.01026	−1.48%	0.0280 → 0.0277
U-235	0.01944	0.01918	−1.37%	0.434 → 0.442
Eu-152m1	0.04037	0.03982	−1.35%	6.22 → 6.37
Mo-99	0.01937	0.01913	−1.28%	5.19 → 5.31
Cd-109m2	0.05791	0.05718	−1.26%	0.712 → 0.727
Re-188	0.007616	0.007526	−1.18%	1.43 → 1.49
Eu-152	0.1523	0.1507	−1.03%	6.24 → 6.37
U-234	0.00001673	0.00001656	−0.99%	0.107 → 0.106
Hg-203	0.03097	0.03072	−0.80%	1.21 → 1.23
Hg-203m	0.1066	0.1059	−0.66%	3.61 → 3.65
Th-228	0.0002269	0.0002254	−0.66%	0.363 → 0.366
In-111m	0.06680	0.06639	−0.61%	3.88 → 3.92
Ta-182	0.1623	0.1617	−0.39%	8.30 → 8.36
Eu-154	0.1581	0.1576	−0.32%	7.52 → 7.56
I-131	0.05216	0.05200	−0.31%	2.32 → 2.34
Cs-137	0.07715	0.07695	−0.26%	5.34 → 5.36
Ba-137m	0.08150	0.08129	−0.26%	5.34 → 5.37
Tl-201m	0.1148	0.1146	−0.23%	3.31 → 3.32
Ir-192	0.1093	0.1091	−0.23%	2.25 → 2.25
Ir-192m1	0.04971	0.04960	−0.23%	1.70 → 1.71
Ce-139m	0.09385	0.09371	−0.15%	6.32 → 6.33
Au-198	0.05458	0.05453	−0.10%	2.77 → 2.77
Rh-106	0.02754	0.02753	−0.02%	4.79 → 4.79
Sb-124m1	0.05991	0.05989	−0.02%	4.70 → 4.71
Rh-106m	0.3674	0.3673	−0.02%	6.39 → 6.40
Cs-134	0.2074	0.2074	−0.01%	5.85 → 5.86
Sb-124	0.2257	0.2257	−0.01%	7.97 → 7.97
U-238m	0.2292	0.2292	<0.01%	13.6 → 13.6

A nuclide with a sheet links to it; every figure there is already the new one.

Ranks, multiples and the stored constant

The rank and the multiple of Cs-137 or Co-60 given on each sheet are now worked out from the same Γ the sheet prints, rather than from a stored copy rounded to six decimal places; for Pm-147, whose constant is the smallest, the multiple of Cs-137 roughly doubles. That stored constant, which the gamma calculator and the nuclide list display, had drifted from the sheets for seven nuclides, by up to 0.4% for Eu-152, and has been recomputed.

Beta branches added for 27 nuclides

The data carried no beta-minus branch for 27 nuclides that emit one: Au-198, Ce-141, Cs-134, Cs-137, Eu-152, Eu-152m1, Eu-154, Fe-59, Hg-203, Ir-192, K-40, Kr-85m, Lu-177, Lu-177m, Na-24, Nb-95, Nb-95m, Ra-228, Re-188, Sb-124, Sb-124m1, Sb-125, Sc-46, Sm-153, Ta-182, Xe-133, Zr-95. Their sheets now give the beta endpoint, the range table and the fractions converted to bremsstrahlung, and the beta calculator accepts them.

Bremsstrahlung worked out on the hardest common branch

Beta ranges are still sized on the highest endpoint recorded, however rare its branch, because the shield has to stop the most energetic beta. The bremsstrahlung fraction, and the ranking on the beta shield materials page, now use the hardest branch seen in at least 1% of decays — on the nuclide sheets, on that page and in the beta calculator. Where the highest endpoint belongs to a rarer branch, the fraction converted in lead becomes:

Nuclide	Endpoint used (keV)	In lead before	Now
Co-60	1492 → 317.88	4.28%	0.91%
I-131	806.9 → 606.3	2.32%	1.74%

Eight of the nuclides given beta branches above have their highest endpoint in a branch below 1%, and their fraction is worked out this way from the start — in lead, Au-198 2.76%, Cs-134 1.89%, Fe-59 1.34%, Hg-203 0.61%, Nb-95 0.46%, Sc-46 1.02%, Ta-182 1.70%, Zr-95 2.55%.

Corrections made earlier in this version, September and October 2026

Unit converter: Bq/L and pCi/L had been converted to and from Bq/kg as if a litre weighed a gram, so those answers were wrong by a factor of a thousand. Volume and mass concentrations are now separate quantities, and crossing between them asks for a density.
Detection limits: the scan MDC is calculated in dpm/100 cm² but had been labelled Bq/cm², so in the unit shown it read six thousand times too high, as did the line converting it. The unit and the conversion are now right.
Specific activity is computed from AME2020 atomic masses instead of the mass number. Every value changed, by at most about half a per cent (H-3).
Beta range: the Katz–Penfold fit changes branch at 2.5 MeV, not at 3 MeV as coded before, which moved one nuclide, Pr-144, by 0.69%. Energies outside the fitted range are now refused rather than answered.
All calculators use the Gregorian year of 365.2425 days, the year on which the IAEA's half-lives in seconds are based; the beta calculator had used 365.25 days.
Inputs with no physical answer, such as a negative dose rate or a counting efficiency above one, are now refused by the detection-limit and work-planning calculators instead of producing a number.

Decay mode labels

Ir-192 had been labelled electron capture, although about 95% of its decays are beta-minus; the label now says beta-minus decay. Eu-152, labelled electron capture with beta-plus, now reads electron capture and beta-minus decay: beta-plus is a trace branch and beta-minus takes 27.9% of decays. Earlier in this version the labels of Pu-241 (beta-minus, not alpha), Nb-95m (isomeric transition, not beta-minus), and Cl-36 and K-40 (beta-minus, not electron capture with beta-plus) were corrected in the same way.

Statements of accuracy, and generated sentences

Two claims the validation reports do not support were removed: that the Katz–Penfold range fit is good to about ±10%, and that the gamma constants agree with published values to within about 2%. The pages now say what the reports do show. Generated sentences on the nuclide sheets that contradicted the sheet's own figures were corrected — decay captions, shielding verdicts, ranking phrases, and verdicts now limited to a nuclide's own photons where its decay chain or spontaneous fission sets the field of a real source. None of these changes a number.

Air kerma and µSv/h

The gamma figures are air kerma. Where they are set against a µSv/h target, 1 µGy is counted as 1 µSv; every page that does so now says so, and Methods sets out the energy dependence that convention leaves aside. The values themselves are unchanged.

1.0.1 — 16 September 2026

The first release archived on Zenodo with a DOI: calculators for gamma dose rate and shielding, beta dose rate and shielding, decay, specific activity, unit conversion, detection limits and work planning, with reference sheets for all 147 nuclides. A 1.0.0 release published on GitHub half an hour earlier was not archived; 1.0.1 differs from it only in the wording of the NIST notice.