The Isotopic Power is obtained from the average decay energies.
The range of alpha and beta particles in solid material is small. As a result, radionuclides can generate substantial amounts of heat due to the kinetic energy of the emitted particles being transformed into heat. If all the emitted alpha and beta particles are retained in the material, the Isotopic Power, i.e. the heat generated per unit time per unit mass is given by
Isotopic Power (α) = A · [E“α”]
Isotopic Power (α + β) = A · [E“α” + E“ß”] ,
where A is the specific activity, and E“α” and E“ß”, the average energies per disintegration associated with heavy particles and electrons. The unit of isotopic power is (W/g). If one is interested in bulk material, it is useful to consider in addition the deposition of the gamma energy in the material. The total isotopic power is then
Isotopic Power (α + β + γ) = A · [E“α” + E“ß” + E“γ”] .
The values of the isotopic power given in the Nucleonica Nuclide Datasheets / Derived Data are for the parent isotope only. In some cases, the parent decays to a short-lived daughter, which can also contribute strongly to the isotopic power. Some important examples are
90Sr (daughter 90Y half-life 2.6 d),
106Ru (daughter 106Rh half-life 29.8 s),
137Cs (daughter 137mBa half-life 2.55 m),
144Ce (daughter 144Pr half-life 17.3 m).
In such cases, one has to evaluate the full decay chain. These nuclide mixtures already exist (or can be created) in Nucleonica's Nuclide Mixture application.