My radioactivity calculation program has the capability to calculate and predict radiation products from many complicated types of radioactive decay chains in which a heavy element decays into another radioactive element which sometimes decays into either of two other radioactive elements and so on. However, there are two potentially significant phenomenon which are not covered by the program: Spontaneous fission, and induced fission.
The program is not yet ready to handle induced fission (fission caused by nuetron-nucleus collisions, like that which is utilized in uranium reactors to generate heat) because the three-dimensional arrangement of the nuclei must be considered in order determine induced fission rates. But spontaneous fission is a phenomenon that the program should be able to take into account without adding a 3D CAD framework.
Spontaneous fission is a natural occurrence in very heavy nuclei in which a percentage of the nuclei simply split apart rather than emit an alpha or beta particle. Spontaneous fusion events typically emit a much higher energy than other radiation types, but it is also rare In uranium isotopes. For larger nuclei such as some plutonium isotopes, spontaneous fission becomes a significantly common form of decay, and thus a significant contributor to the energy emitted by samples of those isotopes.
Therefore, Radioactivity_Sim should account for spontaneous fission in order to produce accurate results for those isotopes. This will require a modification to both the format of the input files, and to the parsing software which reads and interprets them. What makes spontaneous fusion a challenging addition to the program is that it increases the total number of potentially active nuclei, and the program is not currently capable of accounting for that. Intrigueingly, alpha emissions also typically increase the number of nuclei because an alpha particle is a helium nucleus with a high kinetic energy, and modeling alpha emissions within the program as if they were spontaneous fission reactions could make it simpler for future models of secondary interactions at the alpha particle end points.