Radiolysis of mixed solutions of Cl-and Br-and its effect on corrosion of a low-alloyed steel

摘要

Experimental and model simulation studies on gamma-radiolysis of mixed solutions of sodium chloride and sodium bromide were carried out for a better understanding of general corrosion of steels,which are exposed under the synergistic environments of gamma ray and seawater.In seawater,the concentration of bromide ion is very low compared with that of chloride ion.However,it played an important role in the water radiolysis process,and accelerated the production of oxidants,such as hydrogen peroxide and oxygen.The effect of this change of the water radiolysis process caused by chloride and bromide ions on corrosion rate of a low-alloyed steel was investigated through immersion tests under gamma-ray irradiation.It was found that the corrosion rate increased with increasing in the concentration of bromide ion.The corrosion rate was also measured in various pH conditions,and it increased similarly to concentrations of oxidants produced through radiolysis of the solutions except for strong alkaline solutions.The corrosion rate decreased drastically when pH was kept over 11,though the concentrations of oxidants were high due to addition of bromide ion.It was considered that the low corrosion rate attributed to enhancement in the passivity of test specimens under the higher pH conditions.