Answer
The positive sign of Q isn't the only parameter for the sucessful spontaneous fission of elements. The nucleus must overcome the energy barrier which might be larger than the calculated Q and therefore, the reaction does not occur spontaneously.
Work Step by Step
The positive sign of Q isn't the only parameter for the sucessful spontaneous fission of elements. The nucleus must overcome the energy barrier which might be larger than the calculated Q and therefore, the reaction does not occur spontaneously.