Research On The Influence Of Environmental Factors On Water Radiolysis Products

The interaction mechanism between high energy rays and water is one of the cornerstones in radiobiology,environmental protection and reactor water chemistry.It is of great significance in biological organism damage,pollutant degradation,safety construction of reactor,etc.The mechanism of water radiolysis is mainly the energy deposition of high energy rays in water,resulting in the formation of active radicals(·OH,·H,e^-_aq,etc)and molecules?H2,H2O,etc?.The above primary radiolysis products are greatly affected by the type of solute,the concentration of solute,the oxygen content,temperature and so on.To investigate the effect of these environmental factors on water radiolysis products,different free radical trapping agents were added in the research,and the yield of the final products was analyzed,and the mechanism of water radiolysis based on spurs internal and external reactions was researched.The completed contents and conclusions of this study are as follows:1.A radiation temperature control equipment was set up in the ⁶⁰Co source chamber,and the silver dichromate dosimeter was used for dose calibration of the experimental point in the source chamber and the equipment.The model of dose field in source chamber is constructed by MCNP.Compared with the measured results,the maximum relative deviations of the simulated ones were 15.7%,and the average relative deviation is 8.6%.This model can basically reflect the distribution of the dose field and pave the way for further scientific research experiments.2.The effect of environmental factors on the water radiolysis products was studied on the basis of ferrous sulfate and ceric sulfate system.?1?The gas atmosphere in the system varied with the filling of oxygen,air and argon,and the effect of oxygen concentration on water radiolysis products was studied.The result showed that with the increasing concentration of oxygen,the combination of hydrogen radicals in the spurs was furtherly inhibited,moreover,the competitive ratio outside the spurs was changed simultaneously,finally caused the increase of G(Fe³⁺)and G(Ce³⁺).?2?The effect of solute concentration on water radiolysis products was studied by changing the initial concentration of ferrous ions in ferrous sulfate solution,cerous ions and ceric ions in ceric sulfate solution.The results show that for the ferrous sulfate system,the increasing concentration of ferrous ions can promote water radiolysis and increase the yield of the primary products of water radiolysis,the positive effect on G(Fe³⁺)can counteract the negative effect caused by the external spurs reaction.For the ceric sulfate system,the rise in the concentration of cerous ions will increase the production of hydroxyl radical and thus decrease G(Ce³⁺)while the rise in the concentration of ceric ions leads to a higher production of hydrogen radical and thereby increaseing G(Ce³⁺).?3?The effect of temperature on water radiolysis products was studied by changing the irradiation temperature of ferrous sulfate solution and ceric sulfate solution.The results show that the spurs time is shortened with the rising temperature,and the diffusion and combination rate of free radical in spurs are accelerated simultaneously.However,the final result is that the diffusion is stronger than the combination,which leads to more free radical production and less molecular yield outside the spurs.Besides,the hydroxyl radicals increase faster with temperature than other species,which further leads to the positive temperature coefficient of G(Fe³⁺)and the negative temperature coefficient of G(Ce³⁺).