Activation analysis and radioactive waste assessment for COOL blanket in CFETR

This work presents a comprehensive activation analysis for the supercritical CO 2 cooled lithium lead (COOL) blanket proposed for the Chinese Fusion Engineering Test Reactor (CFETR). The COOL blanket features tungsten carbide shielding, liquid PbLi breeding, and SiC/SiCf flow channel inserts that differ significantly from established water-cooled ceramic breeding (WCCB) and helium-cooled ceramic breeder (HCCB) concepts. A 3D neutronics model was developed using DAG-MCNP with FENDL-3.1d nuclear data, coupled with FISPACT-II inventory calculations to evaluate activation responses across all COOL components. The analysis focused on impurity-driven activation mechanisms and included benchmarking against WCCB baseline data. The calculations indicate that the COOL configuration yields more favourable waste-management metrics than the alternative blanket concepts considered to date. WC shielding achieves low-level waste (LLW) status within 1–3 years versus 100+ years for conventional steel shielding, while PbLi breeder material potentially enables immediate recycling following tritium extraction. Contact dose rates decay from 1e3 Sv/h at shutdown to <1e-2 Sv/h within 30 years, with 15% lower decay heat density than WCCB based on this analysis. Long-term activation is controlled by 94 Nb from tungsten impurities and 108m Ag from PbLi contamination. Under Chinese regulatory standards, all COOL components achieve LLW classification within 1–30 years, potentially enabling >90% material recovery through proposed recycling processes that require further development and validation. The activation dataset assembled here supports the licensing case for deploying the COOL blanket in CFETR and clarifies the associated advantages for waste handling.