ence ▁flu or ides . ▁Most ▁dif lu or ides ▁and ▁trif lu or ides ▁have ▁high ▁bo iling ▁points , ▁while ▁most ▁t etra flu or ides ▁and ▁mon of lu or ides ▁fall ▁in ▁between . ▁▁ ▁The ▁term ▁" flu or ide ▁vol at ility " ▁is ▁j arg on ▁used ▁particularly ▁in ▁the ▁context ▁of ▁separation ▁of ▁rad ion u cl ides . ▁ ▁Vol at ility ▁and ▁val ence ▁ ▁Val ences ▁for ▁the ▁majority ▁of ▁elements ▁are ▁based ▁on ▁the ▁highest ▁known ▁flu or ide . ▁ ▁R ough ly , ▁flu or ide ▁vol at ility ▁can ▁be ▁used ▁to ▁remove ▁elements ▁with ▁a ▁val ence ▁of ▁ 5 ▁or ▁greater : ▁u ran ium , ▁ne pt un ium , ▁plut on ium , ▁metal lo ids ▁( t ell ur ium , ▁ant im ony ), ▁non met als ▁( selenium ), ▁hal og ens ▁( iod ine , ▁b rom ine ), ▁and ▁the ▁middle ▁transition ▁met als ▁( nio b ium , ▁mol y b den um , ▁te ch net ium , ▁r uth enium , ▁and ▁possibly ▁rh od ium ). ▁This ▁fraction ▁includes ▁the ▁act in ides ▁most ▁easily ▁re usable ▁as ▁nuclear ▁fuel ▁in ▁a ▁thermal ▁re actor , ▁and ▁the ▁two ▁long - l ived ▁f ission ▁products ▁best ▁su ited ▁to ▁dispos al ▁by ▁trans mut ation , ▁T c - 9 9 ▁and ▁I - 1 2 9 , ▁as ▁well ▁as ▁Se - 7