Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
fission [ˈfɪʃən] n расщепле́ние
atomic or nuclear fission а́томное or я́дерное расщепле́ние
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.
Русский: