As Kori-1 permanently shut down in Korea, it is expected that a large amount of radioactive waste will be generated during decommissioning of nuclear power plants. Radioactive concrete waste is contaminated up to depth of 100 mm with radionuclides such as 137Cs and 60Co. The radioactive waste should be accurately classified to reduce the cost of disposing of radioactive waste. Therefore, the specific radioactivity of waste must be precisely evaluated by gamma-ray measurements emitted from the radionuclides. In general, the effectiveness of the radioactivity measurement and process is confirmed using certified reference material (CRM) composed of water or agar. However, the decommissioning waste differs from this CRM in apparent density and chemical elements, so the specific radioactivity is underestimated or overestimated. Therefore, reference material composed of the same apparent density and chemical elements as the sample is required to improve the quality of radioactivity measurement. The purpose of this study is to develop a concrete reference material for the nuclear decommissioning waste. The concrete reference material composed of SiO2, CaO, and Al2O3 were manufactured in compliance with ISO Guide 35. 10 bottles were randomly selected for homogeneity test, and 2 samples for analysis were taken from each bottle. The specific radioactivity was measured using an HPGe detector with an efficiency of 30%. The results of the homogeneity test of 137Cs and 60Co satisfied the requirements of ISO Guide 35. Coincidence summing and selfabsorption effects were corrected using the Monte Carlo efficiency transfer code and Monte Carlo NParticle transport code. The reference values of 137Cs and 60Co in the concrete reference material were evaluated in the range of 1,000–1,100 Bq·kg−1 and extended uncertainty was around 7%.

NFDC (Nuclear Fuel and materials Data Center) developed standard reference data for oxidation of HANA-6 cladding material. Thermo-gravimetric analyzer (TGA) was used to measure oxidation, and the measuring device was self-calibrated using standard materials. The oxidation amount of the HANA6 cladding was measured in an oxidizing atmosphere in the temperature range of 400 to 700°C. Through this, oxidation data, oxidation rate model equation, and graph were developed. The uncertainty factors were analyzed from the oxidation model. The expanded uncertainty of oxidation data was calculated by evaluating the uncertainty for each uncertainty factor. The oxidation data produced in this study was self-rated through deliberation by a specialized committee of NFDC and third experts. It was finally registered as a reference standard through the technical committee of the National Reference Standards Center. It is believed that the standard reference data developed in this study will be helpful for increasing reliability and stability evaluation of nuclear fuel and spent fuel.

유리 표준물질은 정밀 지구화학 분석법에 필수적으로 이용되는 표준물질이다. 기존의 합성 유리 표 준물질의 단점인 자연 암석과의 조성 차이로 인한 높은 불확실성을 보완하기 위해, 자연산 암석을 이용하여 유리 표준물질을 제작하였다. 백두산 흑요암인 NK-B1G 시료는 미세결정이나 포유물 등의 결정을 포함하지 않는 자연 유리질 암석으로, EPMA나 LA-ICPMS 분석 등의 미세분석을 위한 표준물질로서의 적합성을 확인 하였다.

The National Environmental Specimen Bank (NESB) has set up a plan to develop reference materials in the facility for assuring analytical quality and validating analytical methods for its monitoring samples. Some of the crucial characteristics that reference materials must consist of are homogeneity and stability of both intra and inter-bottles. In this study, we examined the homogeneity and stability of cryogenically-milled muscle samples, from Common Carp (Cyprinus carpio) for total mercury. Homogeneity was tested using ANOVA analysis and regression analysis was used to test short-term stability. The variations of total mercury concentration did not significantly differ between the intra and the inter-bottle (F=0.8, p=0.37). Additionally, relative standard deviation of the total mercury concentration showed low values (2.28%). For the short-term stability test, total mercury variations were not statistically significant as demonstrated by the result of the regression analysis (F ratio = 3.11, p = 0.18). This suggests that the cryogenic-milling process has statistically proven the degree of homogeneity and short-term stability for samples of carp muscles in the chemical analysis for total mercury.

The National Environmental Specimen Bank (NESB) has been sampling and cryogenically preserving various wildlife specimens to monitor bio-accumulations of chemical pollutants since 2010. Recently, the NESB set up a plan to develop reference materials at their facility to assure the analytical quality of and validate the analytical methods for their monitoring samples. One of the crucial characteristics of reference materials is intra- and inter-bottle homogeneity. In this study, we used ANOVA for total mercury concentrations in some samples to validate their homogeneities after milling and homogenization. We examined the intra- and inter-bottle homogeneities of two cryogenically-milled samples (Korean mussel (Mytilus coruscus) and black-tailed gull’s egg (Larus crassirostris). The variations in the total mercury concentrations were not significantly different intra- and inter-bottle (mussel: F=0.74, p=0.67; gull egg: F=1.96, p=0.10). Additionally, the relative standard deviations of the total mercury concentrations showed low values (mussel: 2.02%, gull egg: 1.78%). Therefore, the cryogenic-milling process statistically proves the homogeneity of the materials of mussels and sea gull eggs for chemical analysis for total mercury.