Technological assessment between vertical and horizontal remote maintenance schemes for DEMO reactor

Preliminary assessment for two options of remote maintenance, the banana shape segment transport using all vertical maintenance ports (BSAV) and saddle-shaped segment transport using limited number of horizontal maintenance ports (SSLH), is carried out to establish a feasible maintenance scheme on the DEMO design, focusing the plasma vertical stability, in-vessel transferring mechanism of blanket segment and divertor, and pipe connection. Analysis on the plasma vertical stability indicates that the BSAV scheme with double-loop shell is the most effective on plasma vertical stability. Design and preliminary assessment of in-vessel transferring mechanism and pipe connection were investigated. Although the BSAV has more pipe connection, shutdown dose rate at connection operation area is lower than that on the SSLH scheme. Therefore, the BSAV maintenance scheme would be more feasible scheme for DEMO.