▁cool ing ▁to wers ▁are ▁ ▁tall ▁and ▁provide ▁cool ing ▁to ▁the ▁plant ' s ▁main ▁cond ens ers . ▁ ▁Four ▁smaller ▁mechanical ▁draft ▁cool ing ▁to wers ▁provide ▁nuclear ▁service ▁cool ing ▁water ▁( NS C W ) ▁to ▁safety ▁and ▁auxili ary ▁non - s af ety ▁components , ▁as ▁well ▁as ▁remove ▁the ▁decay ▁heat ▁from ▁the ▁re actor ▁when ▁the ▁plant ▁is ▁off line . ▁ ▁One ▁natural - d raft ▁tower ▁and ▁two ▁NS C W ▁to wers ▁serve ▁each ▁unit . ▁ ▁In ▁ 2 0 0 9 , ▁the ▁N uc lear ▁Reg ul atory ▁Commission ▁( N RC ) ▁renew ed ▁the ▁lic enses ▁for ▁both ▁units ▁for ▁an ▁additional ▁ 2 0   year s ▁to ▁ 1 / 1 6 / 2 0 4 7 ▁for ▁Unit ▁ 1 , ▁and ▁ 2 / 9 / 2 0 4 9 ▁for ▁Unit ▁ 2 . ▁During ▁Vog t le ' s ▁first ▁two ▁units ▁construction , ▁capital ▁invest ment ▁required ▁jump ed ▁from ▁an ▁estimated ▁$ 6 6 0   mill ion ▁to ▁$ 8 . 8 7   b ill ion . ▁($ ▁in ▁ ▁dollars ) ▁ ▁Two ▁additional ▁units ▁util izing ▁West ing house ▁AP 1 0 0 0 ▁react ors ▁are ▁under ▁construction . ▁ ▁Natural - d raft ▁type ▁cool ing ▁to wers ▁were ▁also ▁selected , ▁and ▁the ▁two ▁new ▁cool ing ▁to wers ▁are ▁nearly ▁ ▁tall . ▁ ▁The ▁units ▁have ▁suffered ▁several