1,3-Diethyl-2-Thiourea as a corrosion inhibitor for carbon steel SA 106 GR.B

• The corrosion inhibition of 1,3-diethyl-2-thiourea (DETU) on nuclear material was systematically evaluated. • DETU reduced the corrosion of carbon steel SA 106 GR.B approximately up to 30%. • DETU adsorbs onto the surface of carbon steel, forming a protective layer that suppresses metal oxidation. The corrosion inhibition efficiency of 1,3-diethyl-2-thiourea (DETU) was evaluated in the inorganic-based Hydrazine-Based Reductive Ion Decontamination (HyBRID) solution under actual decontamination temperature conditions. The results showed that adding 0.01 wt% DETU reduced the corrosion depth and rate of carbon steel by ∼30 % (from 9.89 to 6.90 µm and 3.29 to 2.30 µm/h, respectively), and the dissolved iron concentration by ∼27 % (from 193.35 to 140.35 ppm). This inhibition effect is attributed to the strong adsorption of DETU on the carbon steel surface, forming a protective layer. These results suggest that DETU is an effective corrosion inhibitor for structural materials in pressurized heavy water reactors (PHWR) using inorganic acid-based chemical decontamination.