Which type of reaction occurs in the core of a nuclear reactor in a nuclear power plant? Upper H upper C l plus upper N a upper O upper H right arrow upper H subscript 2 upper O plus upper n a upper C l. Superscript 235 subscript 92 upper U plus superscript 1 subscript 0 n right arrow superscript 90 subscript 38 upper S r plus superscript 143 subscript 54 upper X e plus 3 superscript 1 subscript 0 n. Superscript 90 subscript 38 upper S r plus superscript 143 subscript 54 upper X e plus 3 superscript 1 subscript 0 n right arrow superscript 235 subscript 92 upper U plus superscript 1 subscript 0 n. Upper C subscript 10 upper h subscript 8 plus 12 upper O subscript 2 right arrow 10 upper C upper O subscript 2 plus 4 upper H subscript 2 upper O.