Temperature dependence of the Fricke dosimeter and spur expansion time in the low-LET high-temperature radiolysis of water up to 350C; A Monte-Carlo simulation study

Sanguanmith, S.*; Muroya, Yusa*; Tippayamontri, T.*; Meesungnoen, J.*; Lin, M.; Katsumura, Yosuke*; Jay-Gerin, J.-P.*

Monte-Carlo simulations of the radiolysis of the ferrous sulfate (Fricke) dosimeter with low-linear energy transfer (LET) radiation have been performed as a function of temperature from 25 to 350C. The predicted yields of Fe oxidation are found to increase with increasing temperature up to 100-150C, and then tend to remain essentially constant at higher temperatures, in very good agreement with experiment. Moreover, the observed dependence of G(Fe) on temperature largely reflects the influence of temperature upon the primary free-radical product yields of the radiolysis, especially the yield of H atoms. Above 200-250C, the more and more pronounced intervention of the reaction of H atoms with water also contributes to the variation of G(Fe), which may decrease or increase slightly, depending on the choice made for the rate constant of this reaction.