放射 ほうしゃ せい崩壊 ほうかいでしょう
hōshaseihōkaideshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 放射性崩壊

1. Probably radioactive decay.; Likely to decay radioactively.

Polite
Presumptive
Conjecture