The behavior of NAFION membrane was analyzed in presence of high activity tritiated water. The fundamental radiolytical processes have been analyzed by simulation, using quantum mechanical methods. NAFION and PTFE samples were immersed in water and exposed to gamma radiation fields. The samples were characterized by FTIR spectrometry and fluoride emissions. Self radiolytical processes were analyzed by storage of NAFION in high activity triatiated water. The induced modification analyses were carried out using FTIR and fluoride emissions characterization. The experimental results were correlated with quantum-chemical simulations.