Calculator
Shielding thickness
Material thickness required to bring the dose rate down to a target value, from the isotope half-value layers.
Leadmm
Steelmm
Concretemm
- Dose rate without shielding
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- Dose constant K
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- Required attenuation
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Method
t = HVL × log₂(Ḣ₀ / Ḣ_target)
- t — shield thickness in mm
- HVL — half-value layer of the material in mm
- Ḣ₀ — dose rate without shielding in mSv/h
- Ḣ_target — permitted dose rate in mSv/h (µSv/h ÷ 1000)
A ratio of 1 or less means the unshielded dose rate is already below the target: the displayed thickness is zero.
The calculation assumes a broad beam and ignores scatter and build-up, so it understates the thickness actually needed. Add a margin and measure behind the shield before working there.
Indicative result — check it against your authorisation and your dosimetry.