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Disclaimer: This software is for radiation protection education, screening calculations, and professional support only. It does not replace qualified health physicist judgment, regulatory requirements, approved procedures, emergency response tools, or formal shielding design review. Exposure, absorbed dose, equivalent dose, and effective dose are distinct quantities; do not equate R and Sv without explicit context and assumptions.

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Each calculator includes a structured report: app version, units, raw and converted inputs, intermediate steps, formula, assumptions, warnings, provenance references, screening disclaimer, copy summary, JSON/Markdown download, and a print layout.

Calculation report

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Application
HPCalc v1.0.0-alpha.3
Calculator
Decay calculator (example) (decay)
Timestamp (ISO)
2026-04-30T12:00:00.000Z
Unit preference
SI (Bq, Sv, m)

User-selected units

  • initialActivity: mCi
  • outputActivity: mCi
  • elapsedTime: h
  • halfLife: d

Raw inputs

  • nuclide: I-131
  • initialActivity: 10
  • activityUnit: mCi
  • elapsedTime: 24
  • elapsedTimeUnit: h
  • outputUnit: mCi
  • halfLife: 8.02 d

Converted inputs (internal basis)

  • activityBq: 370000000.0
  • elapsedSeconds: 86400.00000
  • halfLifeSeconds: 692928.0000

Intermediate steps

  1. Convert activity and time inputs to base units.
  2. Compute decay constant lambda = ln(2)/halfLife.
  3. Apply A(t) = A0 * exp(-lambda * t).
  4. Convert result to selected output unit.

Remaining activity

7.945 mCi

Formula

A(t) = A0 * exp(-lambda * t), lambda = ln(2)/halfLife

Assumption: Single nuclide exponential decay; half-life treated as exact for the selected nuclide row.
Warning: Parent–daughter ingrowth is not modeled in this example.Warning: Illustrative numbers only.

References / provenance

  • Nuclear decay data for dosimetric calculations (ICRP) [ICRP Publication 107] https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107 [Reference-derived]
  • SI radiation-related units and conversions (reference context) (NIST) [NIST SP 811] https://www.nist.gov/pml/special-publication-811 [Reference-derived]

Screening-use disclaimer

This software is for radiation protection education, screening calculations, and professional support only. It does not replace qualified health physicist judgment, regulatory requirements, approved procedures, emergency response tools, or formal shielding design review.