In an explosion a body breaks up into two pieces of unequal masses both part will have numerically equal momentum and lighter part will have more velocity.

\(U \rightarrow Th + He\)

\(KE _{ Th }=\frac{ P ^2}{2 m _{ Th }}, KE _{ He }=\frac{ P ^2}{2 m _{ He }}\)

sinc \(m_{ He }\) is less so \(KE _{ He }\) will be more.