Calculator Inputs
Choose thickness mode to solve the barrier needed, or dose mode to evaluate a known barrier.
Formula used
This calculator uses a narrow-beam exponential attenuation model with a practical buildup adjustment. It is most suitable for quick photon shielding studies, comparative checks, and early design screening.
For final designs, material spectra, scatter geometry, workload, use factor, occupancy mapping, and code-specific dose limits should be reviewed by a qualified radiation shielding professional.
How to use this calculator
- Select whether you want to solve the required thickness or evaluate the dose through a known barrier.
- Choose a preset material or switch to custom if you already know the attenuation coefficient and density.
- Enter the unshielded dose rate and the distance where that rate is known.
- Enter the protected distance where staff, the public, or equipment will be located.
- For thickness mode, enter the target protected dose rate. For dose mode, enter the known barrier thickness.
- Set the buildup, safety, and occupancy factors to reflect conservative design assumptions.
- Submit the form to view the result, graph, summary table, and export options.
Example data table
| Material | Unshielded dose | Reference / protected distance | Target dose | Buildup | Safety | Occupancy | Estimated thickness |
|---|---|---|---|---|---|---|---|
| Lead | 10 mSv/h | 1 m / 2 m | 0.05 mSv/h | 1.15 | 1.20 | 1.00 | 2.30 cm |
| Concrete | 10 mSv/h | 1 m / 2 m | 0.05 mSv/h | 1.15 | 1.20 | 1.00 | 19.67 cm |
| Steel | 10 mSv/h | 1 m / 2 m | 0.05 mSv/h | 1.15 | 1.20 | 1.00 | 5.31 cm |
Frequently asked questions
1. What does this calculator estimate?
It estimates required shielding thickness or protected dose rate using attenuation, distance, buildup, safety, and occupancy inputs for quick photon barrier studies.
2. Why does distance change the result?
Dose rate falls with the inverse square of distance. Greater separation lowers the unshielded dose reaching the protected point and can reduce the required barrier thickness.
3. What is the buildup factor?
Buildup accounts for scattered radiation that reaches the protected point beyond ideal narrow-beam attenuation. Higher buildup values make shielding requirements more conservative.
4. When should I use custom material values?
Use custom values when you have energy-specific attenuation data from a datasheet, Monte Carlo model, test report, or supplier source for the exact material mix.
5. Are the preset material properties exact?
No. They are practical planning values for quick comparisons. Real attenuation depends on radiation energy, beam quality, material composition, geometry, and construction details.
6. What do HVL and TVL mean?
HVL is the thickness that halves the beam intensity. TVL is the thickness that reduces intensity to one tenth. Both help compare materials quickly.
7. Can this model neutron shielding?
Not reliably. Neutron shielding needs energy-dependent moderation, capture, secondary gamma analysis, and material selection beyond a single attenuation coefficient model.
8. Is this enough for a final facility design?
No. Use it for screening and comparison. Final design should include regulatory dose limits, workload, use factor, occupancy mapping, scatter geometry, and expert verification.