For the final disposal of radioactive waste generated during the operation of nuclear power plants, concentrations of 14 radionuclides including gross alpha have to be determined to meet nuclear regulatory requirements. In order to determine the gross alpha radioactivity in radioactive waste, the sample must be preprocessed into a solution which is usually a strong acid. When this solution is used to prepare the gross alpha measurement sample, it produces a lot of salt, which makes an accurate measurement difficult. Also it causes corrosion of a planchet, which causes problems in the disposal of waste in the future. For these reasons, an acid treatment of the solution was added to the existing preprocess procedure, which is also expected to improve the measurement error. Although the gross alpha measurement is known to be easy to perform and able to give rapid results, it cannot be used for quantitative analysis. This is because the energies emitted by the individual alpha nuclides are assumed to be produced from a single alpha emitted by the individual alpha nuclides are assumed to be produced from a single alpha emitter used as the standard calibration source. Also, due to self-absorption of alpha particles a counting rate depends on the thickness (or weight) of the residues on the planchet. In this study, we compared gross alpha radioactivity with and without an acid treatment to prepare gross alpha measurement samples. The weights of the treated samples increased by at most 5% after about 12 hours of evaporation to dryness, and then saturated or slightly decreased, while the weights of the untreated samples increased up to 20% over time. In addition, the radioactivities of the untreated samples were about two times those of the treated samples. This is considered to be due to differences both in the geometric shapes of the samples and the weights of their residues which resulted from whether acid treatment was applied or not. The results of this study showed that an acid treatment was beneficial in reducing both production corrosion and salts which could result in more reliable and constant measurements of gross alpha activity. The results showed that acid treatment was beneficial in reducing corrosion and measurement errors.

• Kahee Jeong(Central Research Institute, Korea Hydro & Nuclear Power Company Limited, 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon) Corresponding author
• Ji-eun Park(Central Research Institute, Korea Hydro & Nuclear Power Company Limited, 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon)
• Soo Yeon Lim(Central Research Institute, Korea Hydro & Nuclear Power Company Limited, 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon)
• Wook Sohn(Central Research Institute, Korea Hydro & Nuclear Power Company Limited, 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon)