Got this Idea for building a nuclear reactor.  Special coolant (SPCO) would be a very light liquid which expands while COOLED.  Also, It would conduct electricity very fast, and be a super fluid at any temperature so SPCO can flow UP walls. Created by reacting DEUT with LN2.  Reacts violently with NEUT, creating pressure and cooling down, and creating CAUS.

USES:  Very efficiant coolant, as the hotter stuff shrinks, a testing device for heat sensitive circiuts, a self destruct mechanism, the process of formation could be used as a DEUT, or LN2 scrubber.  Also, the crawling up walls would help circiuts or machinery receive coolant without using PIPE or air pressure.

(P.S.  the color would be a greenish red.)