Take some Ibuprofen
The fact is, some of the Uranium’s mass is converted to gamma energy, so there must be a relation.
What is going on at that subatomic level where the atom’s very mass is transforming into that energy? Is it changing forms, or just releasing what is already there. And if it is changing forms, what exact part of the atom is converting to Energy and how.
I suspect it is not a conversion, but a releasing of subatomic particles that are already there.