Before revision: Another undesirable property of Cs-137 extracted from spent nuclear fuel is that it is contaminated with other isotopes of Caesium which reduce power density further , and it also undergoes gamma-decay (advantageous when sterilizing bananas, but not in batteries) .
After revision: Another undesirable property of Cs-137 extracted from spent nuclear fuel is that it is contaminated with other isotopes of Caesium which reduce power density further .