## 2 Materials and Methods  
### Materials  
The study was conducted using materials and methods similar to those of [PERSON] et al. (2023) [25]. As mentioned above, the goal of this study was to manufacture an SRC capable of containing radioactive waste using CW generated by decommissioning. However, it is difficult to bring radioactive CW into the laboratory for experiments. Therefore, CW was simulated by producing the concrete before the experiments and then crushing and grinding it to a size smaller than 0.38 um. There are various methods for manufacturing commercial concrete mixtures. However, strict requirements for concrete are needed for constructing nuclear power facilities, and internationally accepted guidelines, such as American Concrete Institute (ACI) 301 and 304, have been used for that. The general ratios of concrete mixtures used for nuclear power facilities are OPC (10-15 wt%), coarse aggregate (40-45 wt%), and fine aggregate (40-50 wt%) [25; 26; 27]. In addition, FA is recommended for controlling the heat generated by hydration reactions, and the compressive strength of concrete in nuclear power facilities is 30-45 MPa [28]. The concrete used in this study was prepared using the ratio of OPC (20.8 wt%), fine (38.9 wt%), and coarse (40.3 wt%) aggregates with water-to-binder (W /B) ratio of 0.38 wt% [25]. After 28 days of curing, the compressive strength of the manufactured concrete was measured to be 35 MPa. Ground granulated blast furnace slag (GGBPS), a by-product of the pig iron manufacturing process, was obtained from the Pohang Iron & Steel Company, Pohang, Korea, and was used as an admixture (adjusting agent) to improve the workability of the RC [25]. GGBFS did not exhibit any difference in chemical composition according to its particle size, and it was crushed to the same size as CW to improve its capacity for hydration or pozzolanic reaction. Typical alkaline reagents, such as NaOH, KOH, and Ca(OH)\({}_{2}\), were used to enhance hydration reactions [25]. In addition, lime was injected to prevent the quick setting of the RC. CWP underwent the hydration process, and we assessed the optimum incinerating temperature relevant for deriving the rehydration of RC based on the mechanism of pyrolysis [29]. Four temperatures (500 \({}^{\circ}\)C, 600 \({}^{\circ}\)C, 700 \({}^{\circ}\)C, and 800 \({}^{\circ}\)C) were evaluated in a laboratory muffle furnace. Coarse aggregates larger than 5 mm are reported to occupy a high proportion of the waste originating from the nuclear decommissioning process, and they were packed within the manufactured SRC before its diverse properties were investigated [8; 25]. Stepwise experiments were conducted using coarse aggregates, waste soil, and metal waste to measure the maximum capacity of the SRC to solidify radioactive waste. Soil samples having a particle size smaller than 75 \(\upmu\)m were obtained from a site in the vicinity of the Wolsong Nuclear Power Plant, which is one of the operating nuclear power plants in Korea, and they were used to simulate the waste soil [25]. On the contrary, the metal waste belongs to the group of ordinary dismantlement waste, and stainless-steel plate (SUS 304), which is commonly used in the pipeline of nuclear power facilities, was used in the experiments to simulate the metal waste after it was cut into 5 \(\times\) 5 \(\times\) 1 mm pieces [25; 30]. The maximum capacity of SRC to pack coarse aggregate, waste soil, and metal waste was determined when its compressive strength satisfied the acceptance level (3.44 MPa) required by the disposal sites [25]. First, a series of experiments were conducted to investigate the maximum capacity of SRC to contain coarse aggregates because they account for the largest portion of CW originating from decommissioning nuclear facilities [13; 31]. The results indicated that the compressive strength of SRC was acceptable when the coarse aggregate content was 30 wt%.