▁ 4 3 0 ▁t onnes . ▁When ▁all ▁the ▁shield ing ▁and ▁port ▁structures ▁are ▁included , ▁this ▁adds ▁up ▁to ▁a ▁total ▁of ▁ 5 , 1 1 6 ▁t onnes . ▁Its ▁external ▁diameter ▁will ▁measure ▁, ▁the ▁internal ▁. ▁Once ▁assemble d , ▁the ▁whole ▁structure ▁will ▁be ▁ ▁high . ▁ ▁The ▁primary ▁function ▁of ▁the ▁vac u um ▁vessel ▁is ▁to ▁provide ▁a ▁herm et ically ▁se aled ▁pl asma ▁container . ▁Its ▁main ▁components ▁are ▁the ▁main ▁vessel , ▁the ▁port ▁structures ▁and ▁the ▁supporting ▁system . ▁The ▁main ▁vessel ▁is ▁a ▁double ▁w alled ▁structure ▁with ▁pol oid al ▁and ▁tor oid al ▁st iff ening ▁rib s ▁between ▁ ▁shell s ▁to ▁rein force ▁the ▁vessel ▁structure . ▁These ▁rib s ▁also ▁form ▁the ▁flow ▁pass ages ▁for ▁the ▁cool ing ▁water . ▁The ▁space ▁between ▁the ▁double ▁walls ▁will ▁be ▁filled ▁with ▁shield ▁structures ▁made ▁of ▁st ain less ▁steel . ▁The ▁inner ▁surfaces ▁of ▁the ▁vessel ▁will ▁act ▁as ▁the ▁interface ▁with ▁bre eder ▁modules ▁containing ▁the ▁bre eder ▁blank et ▁component . ▁These ▁modules ▁will ▁provide ▁shield ing ▁from ▁the ▁high - energy ▁neut rons ▁produced ▁by ▁the ▁fusion ▁re actions ▁and ▁some ▁will ▁also ▁be ▁used ▁for ▁tr it ium ▁bre eding ▁concepts . ▁ ▁The ▁vac u um ▁vessel ▁has ▁ 1 8 ▁upper , ▁ 1 7 ▁equ atorial ▁and ▁ 9 ▁lower ▁ports ▁that ▁will ▁be ▁used ▁for ▁remote ▁handling ▁operations , ▁di agnostic ▁systems , ▁neutral