Neutronics analysis and assessment of shielding options of pipe forest and Bioshield-Plug design for ITER TBSs

In ITER [1], it is foreseen to have two Test Blanket Systems (TBS) installed in two dedicated Equatorial Ports (EP) for the purpose of testing and validating different concepts of tritium breeding blankets [2]. Each TBS consists of a Test Blanket Module Port Plug (TBM PP) and its associated systems; the Pipe Forest (PF) in the Port Interspace (PI) area and the corresponding systems in the Port Cell (PC) area. While analyses have been conducted before [3], the design has since gone through major evolution with a redesign of the PF, a new BP based on the butterfly doors concept, and an optional activated water delay tank. In this paper, the results of a comprehensive nuclear analyses that aim at assessing the neutronics performance of the revised PF and BP, will be discussed. These include calculations of neutron flux distributions and Shutdown Dose Rate (SDDR), following SA2 [4] scenario, in a baseline configuration and exploring the option of adding additional shielding plates in the PF. It has been found that the additional shielding plates reduces the neutron flux in the PI by ∼40–60% and the SDDR in the PI, due to activated components, by ∼50%.