Safety for the radioactive waste disposed of in the disposal facility should be secured through safety assessment in consideration of the various situations. In this study, the influence and correlation of EDTA and ISA, which are the factors that can impede the safety of the disposal facility, were analyzed using the PHREEQC computational code. Thermodynamic database (TDB) of Andra, specific ion interaction theory (SIT) model as ionic strength correction model, radionuclides (Ni, Am, Pu) were adopted to perform the calculation on the distribution of chemical species by pH. According to the results, EDTA dominated the system and the effect of ISA is relatively small for the distribution of the chemical species of divalent and trivalent cations in neutral and weak base conditions. In the case of the tetravalent cations, the effect of ISA increased compared to the previous case especially in the strong base conditions. In conclusion, EDTA has a more significant effect on the system than ISA under the environment of the domestic disposal facility. Furthermore, when EDTA and ISA are present simultaneously in the system, the effects of two materials are inversely proportional and this characteristic should be considered during the safety assessment.

• Sang June Park(Korea Hydro & Nuclear Power Company Limited, 1655, Bulguk-ro, Munmudaewang-myeon, Gyeongju-si, Gyeongsangbuk-do) Corresponding author
• Moonoh Kim(Korea Nuclear Engineering & Service, 65, Myeongdal-ro, Seocho-gu, Seoul)
• Jun-Yeop Lee(Pusan National University, 2, Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan)
• Hang-Rae Cho(Korea Hydro & Nuclear Power Company Limited, 1655, Bulguk-ro, Munmudaewang-myeon, Gyeongju-si, Gyeongsangbuk-do)
• Suil Bang(Korea Hydro & Nuclear Power Company Limited, 1655, Bulguk-ro, Munmudaewang-myeon, Gyeongju-si, Gyeongsangbuk-do)