DETERMINATION OF THE 129I IN PRIMARY COOLANT OF PWR

Abstract

Among the radioactive wastes generated from the nuclear power plant, a radioactive nuclide such as 129I is classified as a difficult-to-measure (DTM) nuclide, owing to its low specific activity. Therefore, the establishment of an analytical procedure, including a chemical separation for 129I as a representative DTM, becomes essential. In this report, the adsorption and recovery rate were measured by adding 125I as a radio-isotopic tracer (t1/2 = 60.14 d) to the simulation sample, in order to measure the activity concentration of 129I in a pressurized-water reactor primary coolant. The optimum condition for the maximum recovery yield of iodine on the anion exchange resins (AG1 x2, 50-100 mesh, Cl− form) was found to be at pH 7. In this report, the effect of the boron content in a pressurized-water reactor primary coolant on the separation process of 129I was examined, as was the effect of 3H on the measurement of the activity of iodine. As a result, no influence of the boron content and of the simultaneous 3H presence was found with activity concentrations of 3H lower than 50 Bq/mL, and with a boron concentration of less than 2,000 μg/mL.

Keywords

• 129I
• 125I
• Primary Coolant
• Anion-exchange Resin
• H3BO3
• 3H