Fuel Burnup Calculator Form
Plotly Graph
Example Data Table
| Sample Case | Heavy Metal Mass | Thermal Power | Days | Capacity Factor | Energy Produced | Burnup | Approx. FIMA |
|---|---|---|---|---|---|---|---|
| Reference assembly screening | 500 kg | 30 MW | 900 | 92% | 24,840 MWd | 49.68 GWd/tU | 4.968% |
| Moderate cycle case | 450 kg | 20 MW | 700 | 88% | 12,320 MWd | 27.378 GWd/tU | 2.738% |
| Extended exposure case | 520 kg | 32 MW | 1,000 | 94% | 30,080 MWd | 57.846 GWd/tU | 5.785% |
Formula Used
Energy (MWd) = Thermal Power (MW) × Irradiation Time (days) × Capacity Factor
Burnup (MWd/tU) = Energy Produced (MWd) ÷ Heavy Metal Mass (tU)
Burnup (GWd/tU) = Burnup (MWd/tU) ÷ 1000
Power Density (MW/tU) = Thermal Power (MW) ÷ Heavy Metal Mass (tU)
Specific Energy (MWh/kgU) = Energy Produced (MWd) × 24 ÷ Heavy Metal Mass (kg)
Estimated Fissions = Thermal Energy (J) ÷ Energy per Fission (J)
U-235 Equivalent Consumed (kg) = (Estimated Fissions ÷ Avogadro Number) × 235 ÷ 1000
FIMA (%) ≈ 0.1 × Burnup (GWd/tU)
This calculator is meant for educational, screening, and planning use. Detailed reactor physics, depletion libraries, and licensing work need validated core-design methods.
How to Use This Calculator
- Select a calculation mode based on your goal.
- Enter heavy metal mass in kilograms.
- Provide thermal power, irradiation days, and capacity factor.
- Enter target burnup only when estimating days or power.
- Add enrichment and energy per fission for advanced estimates.
- Press the calculate button to show results above the form.
- Review burnup, energy, fissions, utilization, and the graph.
- Use the CSV or PDF button to export your result set.
Frequently Asked Questions
1) What does fuel burnup measure?
Fuel burnup measures how much energy a fuel mass has delivered during irradiation. It links reactor output to fuel utilization and commonly appears as MWd/tU or GWd/tU.
2) Why is heavy metal mass used?
Heavy metal mass is the usual reference basis for uranium-bearing fuel. It gives a consistent denominator for comparing fuel exposure, utilization, and operating strategy across different cases.
3) What is capacity factor doing here?
Capacity factor adjusts ideal full-power operation to a more realistic average. It accounts for downtime, transients, partial loading, and real operating conditions across the irradiation period.
4) Is the U-235 consumed value exact?
No. It is an equivalent estimate based on thermal energy and assumed fission energy. Actual depletion depends on isotopic shifts, plutonium production, neutron spectrum, and detailed burnup modeling.
5) What does FIMA mean?
FIMA means fissions per initial metal atom. It expresses the fraction of original heavy atoms that have undergone fission. This calculator uses a simple rule-of-thumb approximation.
6) Can I use this for licensing decisions?
No. This page is suitable for education, quick checks, and preliminary planning. Licensing, safety, or design work should rely on validated depletion codes and approved engineering methods.
7) Why are there different calculation modes?
Different workflows need different unknowns. Sometimes you know operating conditions and want burnup. Other times you need the days or power required to reach a target burnup.
8) What units should I enter?
Enter heavy metal mass in kilograms, thermal power in megawatts, irradiation time in days, capacity factor in percent, and target burnup in GWd/tU for consistency.