( ( According ( to ( nuclear scientists ) ) ) ( , ( this ( ( can ( be ( ( as ( long ( ( as ten ) thousand ) ) ) ( to ( a ( ( hundred thousand ) years ) ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (VBG According) (PP (TO to) (NP (JJ nuclear) (NNS scientists)))) (, ,) (NP (DT this)) (VP (MD can) (VP (VB be) (NP (NP (QP (RB as) (JJ long) (IN as) (CD ten) (CD thousand))) (PP (TO to) (NP (DT a) (QP (CD hundred) (CD thousand)) (NNS years)))))) (. .)))
According to nuclear scientists, this can be as long as ten thousand to a hundred thousand years.
(ROOT (S (NP (DT The) (JJ long-lived) (NNS isotopes)) (VP (VBP require) (NP (NP (NNS thousands)) (PP (IN of) (NP (NP (NNS years)) (PP (TO to) (NP (NN decay)))))) (PP (TO to) (NP (NP (DT a) (JJ safe) (NN level)) (PP (IN in) (NP (DT a) (JJ nuclear) (NN reactor)))))) (. .)))