Leaching yields from an activated aggregate, removal yields from leachate, and overall mass balance relevant to the chemical procedure were investigated on radionuclides of Fe-59, Co-60, and Eu-152 to reduce volume of radioactive waste used in a nuclear reactor facility. The radioactive nuclides were leached with 7 M HNO3 from the aggregate, then the 7 M HNO3 solution was mixed with NaOH or NH3 water to remove the nuclides as a precipitate. 70 - 80 % of Co-60 and 60 - 70 % of Eu-152 were leached from an activated aggregate. 100 % of Fe-59, more than 99 % of Co-60, and 94-98 % of Eu-152 were removed as a precipitate at pH higher than 4, 7, and 6, respectively. Removal rates became lower at pH lower than 4 for Fe-59, 7 for, Co-60, and 6 for Eu-152. It is basically possible to separate Co-60 and Eu-152 from precipitate of Fe at pH similar to 4. The further separation to reduce volume of waste is not practical, because 20 % of Co-60 and Eu-152 contained in the precipitate. 93 % of volume reduction was achieved with one-step separation.