Enter the activity and gamma energies from your practice problem to estimate exposure rate. You can add a row for each gamma line, with its energy and yield. Optional presets provide editable gamma data for 33 nuclides from ENSDF (NNDC), retrieved through IAEA Nuclear Data Services.
The handbook uses 6 × C × E × N for R/hr at one foot, with activity C in curies, energy E in MeV and yield N per disintegration. The separate 0.5CEN approximation gives the rate at one metre. Choose the method explicitly; changing distance units does not change it. For multiple gamma lines, the calculator sums energy × yield before applying the constant.
The rule is an estimate, with stated accuracy of about ±20% for photon energies from 0.05 to 3 MeV. The calculator identifies lines outside this range and excludes them from the sum. It applies the inverse square law to estimate the rate at your chosen distance.
Results, input checks, source references and accuracy notes are free. Paid membership adds the step-by-step solution and calculator keystrokesKey sequences for 14 calculator optionsScientific — commonly exam-legalTI-30XaTI-30X IIS / IIBTI-30XS MultiViewTI-34 MultiViewTI-36X ProCasio fx-991EX ClassWizCasio fx-115ES PlusCasio fx-300ES PlusSharp EL-W516TOn screen, no handheld neededRadCon calculator (on screen)Graphing / programmable — practice at homeTI-84 Plus CE (and TI-83/84 family)Casio fx-9750GIII / fx-9860GIIIHP 35sNot sure which you haveGeneric scientificChoose the calculator you use to practice. Check with your testing site which models are allowed in the exam..
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Use this calculator for study and reference. For operational radiological work, follow your site’s controlled procedures and approved references.
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