( ( Nuclear energy ) ( ( is ( released ( by ( ( splitting ( ( the nucleus ) ( of ( the atom ) ) ) ) ( into pieces ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Nuclear) (NN energy)) (VP (VBZ is) (VP (VBN released) (PP (IN by) (S (VP (VBG splitting) (NP (NP (DT the) (NN nucleus)) (PP (IN of) (NP (DT the) (NN atom)))) (PP (IN into) (NP (NNS pieces)))))))) (. .)))
Nuclear energy is released by splitting the nucleus of the atom into pieces.
(ROOT (S (NP (JJ Nuclear) (NN energy)) (VP (VBZ is) (VP (VBN released) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT the) (NN nucleus)) (PP (IN of) (NP (DT an) (NN atom)))) (VP (VBZ is) (VP (VBN split))))))) (. .)))