分裂 ぶんれつ物質 ぶっしつじゃありませんでした
bunretsubusshitsujārimasendeshita

Noun
Desu Copula

The polite, past negative form of 分裂物質

1. Was not a fissile material.; Was not a splitting substance.

Past/Perfective
Negative
Polite
Terminal Form