かく分裂 ぶんれつ せい物質 ぶっしつではありませんでした
kakubunretsu sei busshitsudewārimasendeshita

Noun
Desu Copula

The polite, past negative form of 核分裂性物質

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

Past/Perfective
Negative
Polite
Formal Register