Effect of Gamma Radiation on Stability of Silver-Silver Chloride and Mercury-Calomel Commercial Reference Electrodes Available to Purchase

Electrochemical potential measurements of materials in radioactive waste environments will be important in determining if the materials have a propensity for stress corrosion cracking (SCC) and pitting. Potential measurements require a reference electrode (RE), but the effect of ionizing radiation on the potential generated by the RE has been uncertain. Two common types of RE were evaluated under ⁶⁰Co gamma radiation at room temperature. The silver-silver chloride (Ag-AgCl) and mercury-calomel (Hg-Hg₂Cl₂) RE showed essentially no radiation effects up to a dose rate of 2.1E6 rad/h and dose of 9.4E8 rad, indicating these RE would be useful for in-tank studies. The long-lived design of the Ag-AgCl RE showed serious potential deviations at doses of 2.E8 rad but would be the electrode of choice in many situations because it is simple to maintain. The mixed-potential theory was used to explain the radiation effects.