Assessment of Radiation Streaming Effect upon Radiation Loads to Inboard TF-coil of DEMO Utilizing HCLL Blanket

The work presents the results of the detailed analyses performed on the shielding capability of HCLL DEMO-type fusion reactor. The analysis is based on three-dimensional calculations with the Monte Carlo code MCNP-4C and consists in assessment of radiation loads to the super-conducting TF-coil at the inboard side of the reactor. A suitable 20-sector model of DEMO reactor, based on the reactor parameters of PPCS model AB and developed by FZK, have been employed in the analyses. The effect of the toroidal and poloidal gaps between blanket modules upon the responses considered has been investigated. Significant impact of the radiation streaming through the gaps on the radiation load has been observed. The poloidal profiles of the responses in respect to the torus mid-plane have been assessed in several variants of the gap widths and compositions of additional shield plugging the gaps. It was found that the design limit of all the responses considered could only be met if the toroidal and poloidal gaps are plugged by LTS material, the later being made of borated steel, WC and water coolant. The dose absorbed in the Epoxy insulator and the radiation damage to the copper stabilizer were found to be the most critical quantities in this regard.