This study was carried out to evaluate the radiation stability of tributyl phosphate (TBP) extractant by irradiation of ^60Co γ -rays. The degradation products of TBP leads to a decrease of extraction yields and/or formation of the third phase in the solvent extraction system of radioactive waste. TBP was irradiated with ^60Co γ -rays and the degradation products were analysed with gas chromatography - mass spectrometer (GC-MS), liquid chromatography - mass spectrometer (LC-MS), nuclear magnetic resonance (NMR) spectrometer, ion chromatography (IC) and infrared (IR) spectrometer. It was found that the major degradation products from gamma radiolysis of TBP were dibutyl phosphate (HDBP), monobutyl phosphate (H_2MBP) and phosphoric acid. The main radiolysis pathway of TBP may be decomposed to the H_3PO_4 by losing on3 butyl radical step by step in subsequent reactions or losing two~tree but radicals simultaneously like the following ways, that is TBP→HDBP→H_2MBP→H_3PO_4.

방사성 액체폐기물에 함유되어 있는 방사성 핵종의 회수 및 처리에 사용되는 용매 추출제인 tributyl phosphate(TBP)를 인위적인 방법인 ^60Co γ-방사선을 조사시킨 다음 TBP 및 분해생성물을 기체 크로마토그래피-질량 분석법, 액체 크로마토그래피-질량 분석법, 핵 자기공명법(^31P-NMR), 이온 크로마토그래피, 적외선 분광법으로 측정하여 방사선 분해 생성물의 종류와 농도를 정량분석하고, TBP 추출제의 방사선 분해 특성에 대해 기술하였다. 실험결과로부터 TBP는 방사선에 의해 TBP에 결합되어 있는 3개의 butyl 기가 한 개씩 순차적으로 분해되거나, 두 개, 또는 3개의 butyl 기가 동시에 떨어지면서 TBP→HDBP→H_2MBP→H_3PO_4가 생성되는 반응기구로 분해되는 것으로 생각된다.