## 4 Conclusions  
This study evaluated the applicability of RC manufactured using ultralow-level radioactive CWP generated from decommissioned nuclear power facilities as a solidifying agent to safely dispose of radioactive wastes, such as coarse aggregates, waste soil, and metal waste, which are considered the most common and above-medium-level radioactive wastes. Specifically, the optimum mixing ratio of materials, manifestation mechanism of compressive strength, maximum packing capacity of SRC for radioactive wastes, and leachability of SRC were assessed. The following conclusions were drawn:  
1. The XRF results for the chemical compositions of CWP and GGBFS showed SiO\({}_{2}\) and CaO contents of 45% and 19%, respectively. The relatively higher SiO\({}_{2}\) and lower CaO contents indicated that a significant proportion of the powder likely originated from fine aggregates rather than cementitious waste during the crushing, grinding, and separation processes for the pretreatment of CW. However, GGBFS exhibited a more significant CaO content (approximately 37%) and seemed relevant for use as an admixture (adjusting agent) to improve the compressive strength of SRC. 2. The XRD results according to the burning temperatures of CWP indicated that the peaks of \(\beta\)-belite, which are required for the hydration reaction of cement, were not detected at 0-600 \({}^{\circ}\)C, but were identified above 700 \({}^{\circ}\)C. Furthermore, the compressive strength of the SRC met the disposal criterion at incineration temperatures above 700 \({}^{\circ}\)C. Consequently, 700 \({}^{\circ}\)C was found to be the most appropriate incineration temperature for the manufacture of the RC. 3. SRC showed the highest compressive strength when the water-to-binder ratio was 0.4, the GGBFS content was 15 wt%, and CH was used as an alkaline reagent. Among the curing methods tested, the water curing method showed the highest compressive strength (11 MPa) after 28 days of curing. The other methods yielded a compressive strength of 4 MPa and satisfied disposal criteria. 4. Based on the experimental results to elucidate the manifestation mechanism of the compressive strength, CSH was more effective than ettringite in improving the compressive strength of SRC. The SEM results of the microstructure of SRC revealed that ettringite with needle-like crystals could not fill all the pores of SRC; however, gel-shaped CSH effectively filled the pore space by enclosing calcium hydrate and ettringite. In addition, the analytical results of the Raman spectroscopy indicated that the crystallinity of CSH was higher than ettringite, which supports the more significant contribution of CSH than ettringite to the compressive strength of SRC. 5. The total maximum packing capacities of the SRC for coarse aggregate, waste soil, and metal waste were determined to be 30, 5, and 7 wt%, respectively, satisfying the disposal criterion for compressive strength. The results of the leaching tests on the simulated radionuclides, such as Co, Cs, and Sr, met the leachability standards for disposal. Furthermore, the compressive strength of SRC met its criterion after 90-day leaching tests. Overall, this study showed that the radioactive wastes at low and intermediate levels can be safely disposed of by using CW and GGBFS as replacements for OPC. In terms of the industrialization of this process, [PERSON] et al. (2021) proved its feasibility using stepwise experiments on the thermomechanical treatment of radioactive concrete waste [51]. Conceptualization, S.-O.K. ; methodology, J.-H.J. and S.-O.K. ; validation, W.-C.L. and S.-W.L. ; formal analysis, [PERSON]-H.J. and [PERSON]-H.L. ; investigation, J.-H.J. and J.-H.L. ; data curation, W.-C.L. and S.-W.L. ; writing--original draft preparation, J.-H.J. ; writing--review and editing, S.-O.K. ; supervision, S.-O.K. ; project administration, S.-W.L. ; funding acquisition, S.-O.K. All authors have read and agreed to the published version of the manuscript.