Nuclear Fuel Burnup Calculator

Work out nuclear fuel burnup instantly with clear inputs, formula shown and shareable results.

About Nuclear Fuel Burnup Calculator

Burnup measures energy extracted per unit of fuel, in megawatt-days per tonne of heavy metal. Modern light water reactor fuel reaches 45,000-55,000 MWd/tHM at 4-5% enrichment. Roughly 9500 MWd/tHM corresponds to 1% of the heavy metal atoms having fissioned.

Formulas

Burnup

Burnup (MWd/tHM) = thermal energy (MWd) / heavy metal mass (t)

Electrical output

Electrical energy = thermal energy x plant thermal efficiency

Worked example

With the default values below, Nuclear Fuel Burnup Calculator returns Fuel Burnup of 45,000.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Thermal Energy Producedminimum 0 MWd: 45,000 MWd
Heavy Metal Mass Loadedminimum 0 tonnes: 1 tonnes
Initial Enrichmentaccepts 0.1–20 % U-235: 4.5 % U-235
Plant Thermal Efficiencyaccepts 1–60 %: 33 %

Results

Fuel Burnup: 45,000.0
Electrical Energy Generated: 356,400
Heavy Metal Fissioned: 473.6842%
Equivalent Full Power Days: 1,125.0

Step by step

1Values used
2Burnup
3Electrical output
4Fuel Burnup= 45,000.0
5Electrical Energy Generated= 356,400
6Heavy Metal Fissioned= 473.6842
7Equivalent Full Power Days= 1,125.0

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Nuclear fuel management, burnup limits and criticality safety are governed by the reactor licence and regulatory authority. This is an educational estimate only.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Nuclear fuel management, burnup limits and criticality safety are governed by the reactor licence and regulatory authority. This is an educational estimate only.

Frequently Asked Questions

Why does higher burnup need higher enrichment?

More fissile material must be loaded initially to sustain criticality as fissile atoms are consumed and neutron-absorbing fission products build up. Each extra 10,000 MWd/tHM needs roughly one percentage point of enrichment.

What limits burnup?

Cladding corrosion and hydrogen pickup, fission gas pressure inside the rod, and fuel pellet swelling. Licensing limits are set on the fuel rod's mechanical integrity.