( ( ( ( ( ( A ( large ( nuclear-powered ship ) ) ) ( with ( ( more ( than one ) ) reactor ) ) ) , ) ( ( designed ( for ( years ( of service ) ) ) ) ( without refueling ) ) ) , ) ( ( can ( have ( ( ( ( nearly ( as much ) ) ( long-lived radioactivity ) ) ( -LRB- ( ( ( e.g. , ) 90Sr ) -RRB- ) ) ) ( on ( board ( as ( ( an ( operating ( commercial reactor ) ) ) ( -LRB- ( ( ( Rickover , ) 1980 ) -RRB- ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (JJ large) (JJ nuclear-powered) (NN ship)) (PP (IN with) (NP (QP (JJR more) (IN than) (CD one)) (NN reactor))) (, ,) (VP (VBN designed) (PP (IN for) (NP (NP (NNS years)) (PP (IN of) (NP (NN service))))) (PP (IN without) (S (VP (VBG refueling))))) (, ,)) (VP (MD can) (VP (VB have) (NP (NP (QP (RB nearly) (RB as) (JJ much)) (JJ long-lived) (NNS radioactivity)) (PRN (-LRB- -LRB-) (NP (NNP e.g.)) (, ,) (NP (NNP 90Sr)) (-RRB- -RRB-)) (PP (IN on) (NP (NP (NN board)) (PP (IN as) (NP (NP (DT an) (VBG operating) (JJ commercial) (NN reactor)) (PRN (-LRB- -LRB-) (NP (NNP Rickover)) (, ,) (NP (CD 1980)) (-RRB- -RRB-))))))))) (. .)))
A large nuclear-powered ship with more than one reactor, designed for years of service without refueling, can have nearly as much long-lived radioactivity (e.g., 90Sr) on board as an operating commercial reactor (Rickover, 1980).
(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)))))) (. .)))