Three dimensional analysis of radiation streaming through ardzs-cs he-access pipes

The effects of neutron streaming through the divertor He-access pipes of the ARIES compact stellarator fusion power plant on the shielding performance of its components were investigated in this analysis. A 3-D analysis for the most promising design of the He-access pipe with shielding plug and inserts indicated that neutron attenuation through the shielded pipe is not sufficient to eliminate the issue of neutron streaming. The results show that the damage exceeded the limits near the pipe for the manifold, vacuum vessel, and magnet. Precautions should be taken that include changing the pipe design and orientation, avoiding rewelding the manifold and vacuum vessel near the pipe, and/or relocating the magnet away from the pipe. The neutron flux behind the pipe is excessive, mandating additional local shield (~1 m) to protect the externals.