Neutronic analyses of Upper port ECRH antenna system for CFETR.

• 3D full neutronic model of CFETR ECRH was built to deliver the nuclear analysis. • The maximum neutron damage on ECRH antenna appear at the steering mirrors. • Irradiation of VV and TFC can meet the requirements after shielding optimization. • TBR of the whole reactor reduced to 1.137 after 3 ECRH antenna introduced. Electron Cyclotron Resonance Heating (ECRH) is one of the auxiliary heating systems designed for CFETR. The antenna of ECRH system is planned to be plugged into CFETR through 3 upper ports and 2 blanket modules of each port will be penetrated for the transmission of wave. In this study, three dimensional neutronic analysis has been performed to evaluate the shielding effect and conduct the optimization of ECRH antenna design. The simulation has been done on the integration of ECRH antenna system with 22.5-degree CFETR model. The particle transport has been done by MCNP with the support of FENDL-2.1 nuclear data library. An accurate neutron flux distribution has been obtained by employing the 'on-the-fly' global variance reduction technique. The neutron damage of TFC, VV and port was analysed to assess the shielding performance of ECRH antenna system. Initial results demonstrated that the fast neutron fluence and nuclear heating density of TFC and helium production rate of VV port were beyond the design limit. By adding shielding blocks, these parameters didn't exceed the limits. The irradiation damage on antenna components were calculated for estimating its life after neutron irradiation and providing the support of cooling system design. The TBR decreased due to the blanket opening from original 1.149 to 1.137 in the whole reactor. [ABSTRACT FROM AUTHOR]