Shielding & Attenuation
Shielding Attenuation (HVL & TVL)
Calculates transmitted dose rate behind lead, steel, tungsten, concrete, or water shielding barriers, or determines the number of HVLs and TVLs required to reach a target dose rate.
I = I₀ × (0.5)^(N_HVL)
Input Parameters
Calculation Goal
Source & Shielding Material
Pb @ Co-60: HVL = 1.20 cm
Calculated Result & Visual Analysis
Nominal Solved Value Updated automatically
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Enter parameters on the left to calculate.
Geometry & Field Diagram
Interactive Model
Sensitivity Curve
Governing Equation & Parameters
Shielded Exposure (I) = Unshielded Exposure (I₀) × 0.5^(Number of HVLs)
| Symbol | Parameter | Default Unit | Definition |
|---|---|---|---|
| I₀ | R | Incident exposure or dose rate before shielding. | |
| I | R | Transmitted exposure or dose rate exiting the shield. | |
| N_HVL | HVLs | Total barrier thickness expressed in Half-Value Layers (Thickness / HVL). |
Health Physics Notes & Related Calculators
Operational Guidance
- One Half-Value Layer (1 HVL) reduces gamma intensity by 50% (factor of 2). n HVLs reduce intensity by 2ⁿ.
- One Tenth-Value Layer (1 TVL) reduces intensity by 90% (factor of 10): 1 TVL = log₂(10) × HVL ≈ 3.3219 HVLs.
- Linear attenuation coefficient μ = ln(2) / HVL ≈ 0.69315 / HVL (cm⁻¹).
- Narrow-beam HVL calculations do not include scattered photon buildup B(μx); thick broad-beam shields transmit additional scattered dose.
Related Calculators
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