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Plutonium Calculations

Plutonium specific activity by isotope composition

Model-based estimate. Use the stated geometry, composition and measurement assumptions; see the tool scope for limitations.

Input

Plutonium material and isotopic composition

Calculation mode

Reactor-grade plutonium from spent LWR fuel at ~42 GWd/t burnup. Indicative vector; verify against certificate.

Elemental plutonium metal mass

6.33586e+11 Bq/g pure
2.295e+9 Bq/g pure
8.39835e+9 Bq/g pure
3.83991e+12 Bq/g pure
146,306,000 Bq/g pure

Isotope shares are normalised to the composition sum, so they need not add up to exactly 100%.

AssumptionsLoading half-lives...Mass percentages are isotope mass fractions within plutonium, not oxygen/nitrogen compound fractions.Preset compositions are planning defaults; certified material should use its certificate assay.Chemical form conversion uses stoichiometric plutonium mass fraction for the selected material.Result includes Pu isotope activity only; Am-241 ingrowth from Pu-241 decay and chemical toxicity are not included.

Result

Specific activity

5.91981e+11 Bq/g Pu
Activity of entered isotopes
5.91981e+11 Bq
Alpha activity (Pu-238/239/240/242)
1.5995e+10 Bq
Pu-241 share of summed activity
97.3 %
Specific activity, Pu
5.91981e+11 Bq/g Pu
Pu mass fraction
100%
Composition sum
100%
Material mass
1 g Pu
Plutonium mass
1 g Pu
IsotopeMass %ActivityShare
Pu-2382%1.26717e+10 Bq2.14056%
Pu-23953%1.21635e+9 Bq0.205471%
Pu-24025%2.09959e+9 Bq0.354671%
Pu-24115%5.75986e+11 Bq97.2981%
Pu-2425%7,315,280 Bq0.00123573%
Activity contribution
Pu-24197.3%
Pu-2382.1%
Pu-2400.4%
Pu-2390.2%
Pu-2420.0%
Half-life sourcePu-238: 87.7 y · fallback evaluated half-life constantsPu-239: 24,110 y · fallback evaluated half-life constantsPu-240: 6,561 y · fallback evaluated half-life constantsPu-241: 14.29 y · fallback evaluated half-life constantsPu-242: 373,500 y · fallback evaluated half-life constants
  • Result sums only the entered Pu isotopes. Am-241 ingrowth from Pu-241 beta decay (builds up over years and dominates the gamma field of aged plutonium) is not modelled — for aged material provide the material age or certificate.
  • Pu-241 (soft beta, 20.8 keV) dominates the summed activity; it produces neither a gamma field nor external dose — use the alpha activity line as the measure of radiological hazard.

Plutonium Specific Activity Calculator

Formula and isotopes

The calculator computes plutonium specific activity by isotope composition. Isotope specific activity A = N·λ, where the number of atoms N = (m/M)·Nₐ. It covers Pu-238, Pu-239, Pu-240, Pu-241 and Pu-242 with atomic masses from AME2020.

Grades, forms, mass conversion

It supports mass-to-activity and activity-to-mass conversion, ready grade presets (weapons-, fuel-, reactor-grade, MOX) and a custom composition. Chemical forms — metal, PuO₂, nitrate Pu(NO₃)₄ — are converted through the stoichiometric plutonium mass fraction. Grade vectors are indicative; use the material certificate for real material.

What is not included

The result includes only plutonium isotope activity; Am-241 ingrowth from Pu-241 decay and chemical toxicity are not included.

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