Byoung Chul Song

Classification of materials for explosives from prompt gamma spectra by using principal component analysis

Data from the elemental composition-ratios and experimental prompt gamma spectra of samples were used to develop suitable discriminant classes for suspect samples. The collected data and gamma spectra were applied to principal component analysis (PCA) to discriminate explosives from non-explosive materials.

Explosives Detection Using Deuterium-Deuterium Neutron Generator

Gamma spectra of general and explosive materials were obtained by using the developed neutron induced prompt gamma-ray spectrometry system containing a neutron generator, where the neutron source was created from a deuterium-deuterium reaction, and they were examined to establish whether the samples were explosives or not by using the pattern recognition method. When the gamma spectra of real explosives (or general materials) were projected into the already prepared training set for the pattern recognition, they were placed in the categories of explosives (or general materials) properly.

Application of a wet oxidation method for the quantification of 3H and 14C in low-level radwastes

Wet oxidation methods are utilized to separate and quantify (3)H and (14)C radionuclides in inorganic and organic radwastes generated at nuclear facilities. Because (3)H and (14)C are pure beta emitters with half-lives of 12.3 and 5,730 years, respectively, these radionuclides should be chemically separated from other radionuclides present in radwastes for accurate quantification. In particular, a collection technique for (14)C radionuclide in radwastes is needed because it is converted into (14)CO2 gas by an oxidation reaction. To confirm the recoveries of (3)H and (14)C, various standard radioactive sources were used to verify the proposed method. Because the majority of (3)H radionuclides are distributed in tritiated water (HTO), only tritiated water was used as a standard for (3)H radionuclides. Additionally, (14)C-labeled methanol ((14)CH3OH), lauric acid ((14)CH3(CH2)10COOH), sodium bicarbonate (NaH(14)CO3), and toluene (C6H5(14)CH3) were used as (14)C standards. The compounds were oxidized with chemical oxidants and then separated. The individual species were mixed with a scintillation cocktail and counted using a liquid scintillation counter. The recoveries of (14)C and (3)H were 82-97% and 98%, respectively. The wet oxidation method will be applied to RI wastes for clearance.

Investigation on the techniques of quality control for radiation counting systems

In this study, radiation measurement system has been investigated to set up for the radioisotopes analysis in the radioactive waste samples after selecting the radiation counters of alpha beta and gamma nuclides. The counting efficiencies for alpha, beta and gamma measurement systems were calibrated. To obtain stability of the radiation detectors, quality control program has been established. Also, minimum detectable activities (MDAs) depending on the type of samples were calculated for increasing the confidence level for analytical result.