For the disposal of radioactive waste generated from nuclear power plants, characterization of radioactive waste is essential. For characterization, samples of radioactive waste are directly collected or an indirect method is used through X-ray, etc. Through indirect analysis, which is a non-destructive method, the density, filling height, homogeneity and inter structure of the waste container can be analyzed. Currently, foreign institutions are in the process of developing a technology to perform characterization of radioactive waste through indirect analysis. In particular, research on improving internal image accuracy through image analysis techniques, improving measurement methods and enhancing portability for field application is ongoing. Through the review of such technology development trends, it will be utilized in the development of domestic radioactive waste disposal technolgy.

The radwaste facility management team is preparing for clearance of 4 MCAs in The Radwaste Form Test Facility (RFTF). The targeted waste was used for clearance level radioactive waste sample analysis and has been used for this purpose since the early 2000s. Due to the characteristics of clearance level radioactive waste, the concentration of radioactivity is very low and MCA is used with Marinelli beakers the possibility of contamination is low. Moreover, the radiation detector should not be contaminated with radioactive materials, it should be less than the clearance level. These detectors were considered surface contamination materials. To detect the contaminated spot of each material, we scanned the whole surface of a material with a gamma survey meter. After that, we took a sample from 1×1 m2 and a total of 30 samples from each MCA. The wiped filter paper was analyzed with alpha, beta low background counting systems. The results of the analysis of the smear sample of total alpha and beta nuclide radioactivity were less than MDA (α: 2.88×10−5 Bq·cm−2, β: 3.07×10−5 Bq·cm−2). The major nuclide in this facility is Co-60 and Cs-137 therefore we analyzed gamma nuclide activity with HPGe. The maximum specific activity was Co-60: 2.31×10−5 Bq·cm−2, Cs-137: 1.96×10−6 Bq·cm−2. If it is satisfied with the clearance criteria, detectors will be reused at the Radioactive Waste Treatment Facility (RWTF) room # 7251 uncontrolled area.

The geological disposal of spent nuclear fuel is one of the important problems to be solved worldwide. For the safety of the geological disposal, disposal facility is recommended to be constructed in the deep reducing environment of host rocks. As host rocks, rock salt, argillaceous (clay) rock, and crystalline rock have been considered as stable geological formations in various countries. Although various studies have been conducted on crystalline rocks in Korea, there are still few studies on hydrogeochemical evolution in the deep and reducing environment related to the disposal of spent nuclear fuel. Therefore, this study was conducted to identify hydrogeochemical evolution process in granite aquifer which can affect the stability of disposal facility. Groundwater samples for isotope and chemical analysis were collected quarterly adjacent to KURT (KAERI Underground Research Tunnel). As the depth increased, the groundwater changed from Ca-HCO3 type to Na-HCO3 type under the influence of silicate mineral weathering, and the fluorine concentration increased due to the dissolution of fluorine-bearing minerals. However, hydrogeochemical evolution according to the depth was not observed in some wells because of a hydraulic connection through the fracture zone. In addition, the behavior of nitrate and redox-sensitive metals (Fe, Mn, U, Mo) in groundwater was clearly different in the redox condition. Considering these hydrogeochemical processes and hydrogeological factors, a conceptual model of granite aquifers in and around KURT was established. The results of this study will be used as basic data to understand the hydrogeochemical processes and to evaluate and predict the behavior of radionuclides in granite aquifer system.