Radiochemical Separation and Quantification of Tritium in Metallic Radwastes Generated from CANDU Type NPP - 13279
As a destructive quantification method of {sup 3}H in low and intermediate level radwastes, bomb oxidation, sample oxidation, and wet oxidation methods have been introduced. These methods have some merits and demerits in the radiochemical separation of {sup 3}H radionuclides. That is, since the bomb oxidation and sample oxidation methods are techniques using heating at high temperature, the separation methods of the radionuclides are relatively simple. However, since {sup 3}H radionuclide has a property of being diffused deeply into the inside of metals, {sup 3}H which is distributed on the surface of the metals can only be extracted if the methods are applied. As an another separation method, the wet oxidation method makes {sup 3}H oxidized with an acidic solution, and extracted completely to an oxidized HTO compound. However, incomplete oxidized {sup 3}H compounds, which are produced by reactions of acidic solutions and metallic radwastes, can be released into the air. Thus, in this study, a wet oxidation method to extract and quantify the {sup 3}H radionuclide from metallic radwastes was established. In particular, a complete extraction method and complete oxidation method of incomplete chemical compounds of {sup 3}H using a Pt catalyst were studied. The radioactivity of {sup 3}H in metallic radwastes is extracted and measured using a wet oxidation method and liquid scintillation counter. Considering the surface dose rate of the sample, the appropriate size of the sample was determined and weighed, and a mixture of oxidants was added to a 200 ml round flask with 3 tubes. The flask was quickly connected to the distilling apparatus. 20 mL of 16 wt% H{sub 2}SO{sub 4} was given into the 200-ml round flask through a dropping funnel while under stirring and refluxing. After dropping, the temperature of the mixture was raised to 96 deg. C and the sample was leached and oxidized by refluxing for 3 hours. At that time, the incomplete oxidized {sup 3}H compounds were completely oxidized using the Pt catalysts and produced a stable HTO compound. After that, about a 20 ml solution was distilled in the separation apparatus, and the distillate was mixed with an ultimagold LLT as a cocktail solution. The solution in the vial was left standing for at least 24 hours. The radioactivity of {sup 3}H was counted directly using a liquid scintillation analyzer (Packard, 2500 TR/AB, Alpha and Beta Liquid Scintillation Analyzer). (authors)