Model-based estimate. Use the stated geometry, composition and measurement assumptions; see the tool scope for limitations.

Input

Surface contamination and nuclide

Nuclide

E_max 2.27 MeV · CNSC REGDOC-2.7.2 / IAEA-TECDOC-1162 (regulatory)

Surface activity

Unit

Exposure time, h

AssumptionsSkin dose at 70 µm (7 mg/cm²) basal layer, averaged over 1 cm², per ICRP.Uniform thin surface contamination, 2π geometry, no overlying cover or clothing.Each nuclide shows its source: PHITS Monte Carlo, regulatory (CNSC/IAEA) or measured; «≈» marks estimates (±30-50%). For beta QF=1, so mGy = mSv.

Result

Skin dose rate

3.5 mSv/h

Skin dose rate: 3.5 mSv/h (3.5 mGy/h)
Accumulated dose: 3.5 mSv
Fraction of annual skin limit / h: 0.7% (limit 500 mSv/y)
Skin dose factor used: 3.5 mGy·h⁻¹ per kBq·cm⁻²

Beta Skin Dose Rate Calculator

SDR·A formula and 70 µm depth

The calculator estimates the skin equivalent dose rate from surface beta contamination as Ḋ = SDR·A, where A is the surface activity (kBq/cm²) and SDR is the conversion factor at the 70 µm basal-layer depth (7 mg/cm²), averaged over 1 cm² per ICRP. For beta radiation the weighting factor is 1, so mGy·h⁻¹ ≡ mSv·h⁻¹.

Sources of conversion factors

Nuclide factors come not from a formula (the energy dependence is non-monotonic — beta spectrum shape matters more than the maximum energy) but from tables: verified values are Monte Carlo (PHITS, Farhan 2022), estimates are from IAEA-TECDOC-162. Sr-90/Y-90, P-32, Cs-137, Co-60, I-131 and others are supported. For soft beta emitters (H-3, Ni-63) the basal-layer dose is essentially zero — particles do not reach 70 µm.

Output and limitations

The result includes the dose rate, accumulated dose over the working time and the fraction of the annual skin dose limit (500 mSv/y). The model is uniform thin surface contamination with no cover. For safety decisions verify estimate factors against VARSKIN or the primary source.