自発 じはつ かく分裂 ぶんれつじゃありませんでした
jihatsukakubunretsujārimasendeshita

Noun
Desu Copula

The polite, past negative form of 自発核分裂

1. Was not spontaneous fission.; Was not a spontaneous fission event.

Past/Perfective
Negative
Polite
Terminal Form