Free shielding tool · preliminary estimate
Estimate illustrative lead, concrete, or steel thickness from isotope-specific half-value layers using HVL × log₂(initial intensity / target intensity).
Physicist review required before design or construction
A half-value layer reduces photon intensity by half. This tool multiplies the selected illustrative broad-beam HVL by log₂ of the requested attenuation factor, and also reports the corresponding tenth-value layer and unit conversions.
The calculation assumes a point source, one nominal isotope energy, perpendicular incidence, and nominal material density. It does not model scatter geometry, source mixtures, occupancy, distance, workload, buildup beyond the tabulated broad-beam figures, penetrations, regulatory margins, or construction tolerances.
Illustrative broad-beam figures compiled from published references. Confirm every shielding design with a qualified or certified health or medical physicist before design or construction. Verify the exact isotope, spectrum, geometry, density, buildup, occupancy, workload, penetrations, regulatory criteria, and safety margins.
Open the source material and verify the requirements or values that apply to your situation.
Questions to verify
No. It is a preliminary educational estimate. A qualified or certified health or medical physicist must confirm the source term, geometry, occupancy, barriers, margins, and regulatory design.
One HVL reduces intensity by half. One TVL reduces it by a factor of ten and equals HVL × log₂(10) in this simplified exponential model.
Real designs account for spectra, scatter, buildup, distance, workload, use factors, occupancy, penetrations, density, construction tolerances, and required safety margins.
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See Longlead Shielding