▁The ▁patient ▁is ▁then ▁treated ▁with ▁a ▁beam ▁of ▁low ▁energy ▁neut rons ▁at ▁a ▁relatively ▁low ▁neut ron ▁radiation ▁do se . ▁The ▁neut rons , ▁however , ▁trigger ▁ener get ic ▁and ▁short - range ▁secondary ▁alpha ▁particle ▁and ▁l ith ium - 7 ▁heavy ▁ion ▁radiation ▁that ▁are ▁products ▁of ▁the ▁bor on ▁+ ▁neut ron ▁nuclear ▁reaction , ▁and ▁this ▁ion ▁radiation ▁addition ally ▁bomb ards ▁the ▁tum or , ▁especially ▁from ▁inside ▁the ▁tum or ▁cells . ▁ ▁In ▁nuclear ▁react ors , ▁ 1 0 B ▁is ▁used ▁for ▁react ivity ▁control ▁and ▁in ▁emer gency ▁shut down ▁systems . ▁It ▁can ▁serve ▁either ▁function ▁in ▁the ▁form ▁of ▁bor os il icate ▁control ▁ro ds ▁or ▁as ▁bor ic ▁acid . ▁In ▁press ur ized ▁water ▁react ors , ▁bor ic ▁acid ▁is ▁added ▁to ▁the ▁re actor ▁cool ant ▁when ▁the ▁plant ▁is ▁shut ▁down ▁for ▁ref uel ing . ▁It ▁is ▁then ▁slowly ▁filtered ▁out ▁over ▁many ▁months ▁as ▁f iss ile ▁material ▁is ▁used ▁up ▁and ▁the ▁fuel ▁becomes ▁less ▁re active . ▁ ▁In ▁future ▁man ned ▁inter plan et ary ▁space craft , ▁ 1 0 B ▁has ▁a ▁theoretical ▁role ▁as ▁struct ural ▁material ▁( as ▁bor on ▁fib ers ▁or ▁B N ▁nan ot ube ▁material ) ▁which ▁would ▁also ▁serve ▁a ▁special ▁role ▁in ▁the ▁radiation ▁shield . ▁One ▁of ▁the ▁difficulties ▁in ▁dealing ▁with ▁cos mic ▁ray s , ▁which ▁are ▁mostly ▁high ▁energy ▁pro tons ,