▁will ▁be ▁placed . ▁These ▁are ▁designed ▁to ▁slow ▁and ▁abs orb ▁neut rons ▁in ▁a ▁reliable ▁and ▁efficient ▁manner , ▁limit ing ▁damage ▁to ▁the ▁rest ▁of ▁the ▁structure , ▁and ▁bre eding ▁tr it ium ▁for ▁fuel ▁from ▁l ith ium - b ear ing ▁cer am ic ▁p eb bles ▁contained ▁within ▁the ▁blank et ▁module ▁following ▁the ▁following ▁re actions : ▁▁ ▁+ ▁ ▁→ ▁ ▁+ ▁▁ ▁+ ▁ ▁→ ▁ ▁+ ▁ ▁+ ▁▁ ▁where ▁the ▁react ant ▁neut ron ▁is ▁supplied ▁by ▁the ▁D - T ▁fusion ▁reaction . ▁ ▁Energy ▁absor bed ▁from ▁the ▁fast ▁neut rons ▁is ▁extracted ▁and ▁passed ▁into ▁the ▁primary ▁cool ant . ▁This ▁heat ▁energy ▁would ▁then ▁be ▁used ▁to ▁power ▁an ▁electric ity - gener ating ▁tur bine ▁in ▁a ▁real ▁power ▁station ; ▁in ▁I TER ▁this ▁generating ▁system ▁is ▁not ▁of ▁scientific ▁interest , ▁so ▁instead ▁the ▁heat ▁will ▁be ▁extracted ▁and ▁dis posed ▁of . ▁ ▁Techn ical ▁design ▁ ▁V acu um ▁vessel ▁ ▁The ▁vac u um ▁vessel ▁is ▁the ▁central ▁part ▁of ▁the ▁I TER ▁machine : ▁a ▁double ▁w alled ▁steel ▁container ▁in ▁which ▁the ▁pl asma ▁is ▁contained ▁by ▁means ▁of ▁magnetic ▁fields . ▁ ▁The ▁I TER ▁vac u um ▁vessel ▁will ▁be ▁twice ▁as ▁large ▁and ▁ 1 6 ▁times ▁as ▁heavy ▁as ▁any ▁previously ▁manufact ured ▁fusion ▁vessel : ▁each ▁of ▁the ▁nine ▁tor us ▁sh aped ▁se ctors ▁will ▁we igh ▁between ▁ 3 9 0 ▁and