Calculator Inputs
Choose a method, enter values, then calculate.
All outputs are in SI units and common conversions.
Example Data Table
| Scenario | Inputs | What it shows |
|---|---|---|
| Research sample | U-235, 10 g, enrichment 100%, fissioned 1%, efficiency 100% | Total heat released from a small fissioned fraction. |
| Power conversion | U-235, 10 g, enrichment 5%, fissioned 3%, efficiency 33%, time 24 h | Electric-equivalent energy and average power over time. |
| Mass-defect check | Δm = 0.215 amu, scale single, efficiency 100% | Energy per event using E = Δm·c². |
Formulas Used
- Fuel mass method: Events = (mfuel · fenrich · ffission / M) · NA
- Energy from events: E = Events · (Efission in MeV) · 1.602176634×10−13 J/MeV
- Mass-defect method: E = Δm · c², with c = 299,792,458 m/s
- Efficiency (optional): Euseful = E · (η/100)
- Average power (optional): P = E / t
Note: “Energy per fission” is a typical average for each isotope and includes prompt energy releases.
How to Use This Calculator
- Select Fuel mass method for practical fuel estimates.
- Pick an isotope, enter fuel mass, enrichment, and fissioned fraction.
- Set efficiency to model useful output (optional).
- Add a time window to compute average power (optional).
- Press Calculate to show results above the form.
- Use Download CSV or Download PDF for exporting.
FAQs
1) What does “enrichment” mean here?
It’s the percent of the selected fissile isotope in the fuel. The calculator uses it to estimate how much of the fuel can actually undergo fission.
2) What is the “fissioned fraction” input?
It’s the portion of the fissile material that actually fissions. Many real systems fission only a small fraction before fuel is replaced or becomes less reactive.
3) Why are my results different from a textbook value?
Textbooks may use different average energy per fission, include/exclude neutrino losses, or assume specific burnup and enrichment. Adjust inputs to match your scenario.
4) When should I use the mass-defect method?
Use it when you know the mass defect for a specific reaction or want to verify per-event energy from Δm. It’s ideal for conceptual or verification calculations.
5) What does the efficiency setting represent?
It scales released energy into useful energy. For electricity from heat engines, 30–40% is common. For pure heat release, keep it at 100%.
6) Is the TNT equivalent exact?
It’s an energy comparison only, using 1 tonne TNT ≈ 4.184 GJ. It does not describe effects, safety, or real-world blast outcomes.
7) Can I calculate power directly?
Yes. Provide a time window and the calculator estimates average power as energy divided by time. It’s an average, not an instantaneous reactor power profile.