(S (S (BASENP (DT The) (NNS rods)) (VP (MD could) (VP (VB be) (VP (VP (VBN reprocessed) (PP (IN for) (BASENP (JJ several) (NNS months)))) (S (VP (TO to) (VP (VB extract) (BASENP (JJ weapons-grade) (NN plutonium))))))))) (PERIOD .))