afterheat
/ˈɑːftəhiːt/ /ˈaftəhiːt/noun
1Heat that remains or is left over; heat occurring after an initial period of heating or as an after-effect.
2 Nuclear Physics. Heat produced in a nuclear reactor after it has been shut down and fission has stopped.
Origin
Mid 19th century; earliest use found in United States Magazine. From after- + heat.