[en] The purpose of this research is to investigate spent fuel characteristics of High Conversion type core of FLWR (HC-FLWR). HC-FLWR is a new reactor concept and the spent fuel characteristics have been investigated comparing with other types of reactor. It is important for the safety consideration of spent fuel management to investigate the characteristics. For the evaluation of the spent fuel characteristics, the ORIGEN code is widely used. It was also used in this research. However, there are no open ORIGEN libraries for HC-FLWR spent fuel evaluation. Then, the libraries for HC-FLWR were generated using the SWAT code in this research. To investigate the spent fuel characteristics, the decay heat and the radioactivity after a cooling time of 2 years and 4 years were evaluated. As a result, the decay heat and the radioactivity of FP (Fission Product) nuclides from the HC-FLWR spent fuel are almost the same as those of LWRs and full-MOX-LWRs with the discharge burn-up of 45GWd/t, and the decay heat and the radioactivity of actinides are higher than others, because of its large amount of loaded Pu inventory and the Pu composition from the LWR spent fuel including large amount of ²⁴²Pu. However, the Pu vector of the spent fuel is better than that of full-MOX-LWRs, because of the harder spectrum. In addition, from the waste disposal point of view, the characteristics of the heat generation FP elements, the platinum group metals, Mo and the long-lived FPs were also investigated. (author)