Corrosion of Zirconium alloy samples in 340°C circulating water before and after the performance of a decontamination treatment. RCN Report

Nine sets of Zircaloy-2, eleven sets of Zircaloy-2, three sets of Zr-2½ Nb and two sets of Zr-3Nb-1 Sn samples, mainly tube specimens, have been exposed in an out-of-pile water loop for up to 650 dayso The loop test conditions were; 340°C, pH 9-10 with ammonia, oxygen 0.1-0.2 ppm and hydrogen 0.15-0.35 ppm. The measured weight gain data show that the RCN Zircaloy oxidation relations, obtained from autoclave experiments, can be used for long time exposure calculations of the weight gains in circulating water. After an accidental contamination a two step Turco decontamination treatment was given to all samples. The influence of this treatment on the weight gain rate and on the deviations of measured from calculated weight gain is presented and discussed. (author)