A process for the recovery of a radioisotope from a waste resin of a nuclear power plant comprises the steps of: a) treating a waste resin loaded with at least one radioisotope with an organic acid or alkaline compound to release the at least one radioisotope and to obtain a process solution containing the at least one radioisotope; b) separating the at least one radioisotope from the process solution through a reaction specific to the radioisotope so as to obtain a treated process solution depleted of the at least one radioisotope, wherein said depleted process solution comprises the organic acid or alkaline compound and optionally a non-reacted radioisotope; c) reacting the organic acid or alkaline compound in the depleted process solution from step b) by thermal and/or photochemical oxidation to form gaseous reaction products; and d) reloading the waste resin with the reacted process solution from step c) to bind the non-reacted radioisotope on the waste resin. Further, an apparatus is provided to carry out the above method.