Great start

Great visuals but the decays are just wrong. Getting a decay probability or fission yield probability for each isotope and applying it would be the next step. When an isotope naturally decays or fissions to a different atom the program should simulate that. All the information is out there if the devs want it, a good nuclear physicist consultant on the payroll could turn this into an app from a sweet visual to a serious demo tool used in every physics class worldwide.

Spar-10 about Nuclear