Plan radiation safety distance with practical source inputs. Check dose targets, shielding impact, and exposure time. Export clean results for records and review.
Use verified source data. This calculator supports planning checks only. Final safety decisions should follow site procedures, regulations, and qualified radiation protection review.
| Case | Activity | Gamma Constant | Time | Shielding | Occupancy | Decay | Dose Limit | Required Distance |
|---|---|---|---|---|---|---|---|---|
| Co-60 area check | 3.70 GBq | 80.00 | 1.00 h | 0.50 | 1.00 | 1.00 | 20.00 µSv | 2.720 m |
| Cs-137 corridor check | 1.85 GBq | 21.00 | 0.50 h | 0.80 | 0.50 | 1.00 | 10.00 µSv | 0.881 m |
| Ir-192 temporary zone | 0.74 GBq | 130.00 | 0.25 h | 0.30 | 1.00 | 0.95 | 7.50 µSv | 0.956 m |
This page uses the inverse square approach for point-source dose estimation.
Dose = (Γ × A × t × S × O × D) / r²
Required Distance = √[(Γ × A × t × S × O × D) / Dose Limit]
Γ is the gamma constant. A is activity in GBq. t is time in hours. S is shielding factor. O is occupancy factor. D is decay factor. r is distance in meters. Lower shielding, occupancy, or decay factors reduce the final dose.
Enter the source activity first. Choose the correct unit. Add the gamma constant for the isotope or source setup. Enter the planned exposure time and the target dose limit. Include shielding, occupancy, and decay factors when they apply. Add the actual working distance if you want to test an existing location. Press the calculation button. The page shows the required distance, predicted dose at the tested distance, the dose target, and the margin. Export the result as CSV for logs or PDF for reports. Always verify the source term, geometry, and shielding assumptions before using the output in any real work instruction.
Distance is a core radiation protection control. Dose from a small source falls quickly as distance increases. That change follows the inverse square rule. Double the distance and the dose rate drops to one quarter. This makes distance a practical planning tool.
This calculator estimates the spacing needed to keep exposure at or below a chosen limit. It combines source strength, gamma constant, exposure time, shielding, occupancy, and decay. The output helps compare work positions, barriers, and temporary exclusion zones.
Use it during task reviews, area layout checks, and temporary source planning. It also helps when you need a fast estimate for posted boundaries. The result is useful for screenings and early design decisions.
The model assumes point-source style behavior. Real fields can differ. Scatter, source size, beam direction, wall reflection, and irregular shielding can change results. The gamma constant must match the source and units. Activity and time must be accurate.
Shielding factor lets you model attenuation simply. Occupancy factor adjusts for partial presence in the area. Decay factor helps when source output changes over the task period. These factors make the estimate more practical than a simple distance-only method.
The required distance is the minimum estimated spacing for the chosen limit. The predicted dose at the actual distance shows whether a planned location stays below the target. A positive margin means the tested distance is above the minimum. A negative margin means the location is too close.
Use this tool as a planning aid, not a final authorization method. Confirm data with approved source records and radiation surveys. Then compare the result with site limits, procedures, and professional review before work starts.
It uses an inverse square dose model. The calculation multiplies gamma constant, activity, exposure time, shielding, occupancy, and decay factors, then divides by distance squared.
The gamma constant connects source strength to dose rate at distance. Different isotopes and emission patterns can produce very different constants.
A shielding factor reduces the unshielded dose estimate. A value of 1 means no reduction. Smaller values represent stronger attenuation.
It adjusts exposure for the time a person is actually present. A value of 0.5 means the person is in that location half the time.
No. It is best for simplified point-source style estimates. Complex geometry, scatter, beams, and large sources need more detailed analysis.
It means the tested distance is smaller than the required distance. The location may exceed the selected dose target.
Some tasks involve changing source strength over time. The decay factor helps approximate that reduction in the planning estimate.
No. Use it for screening and planning. Final decisions should rely on approved procedures, measured data, regulations, and qualified radiation safety review.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.