Very few, if https://en.wikipedia.org/wiki/Integrated_electric_propulsion#List_of_IEP_ships https://en.wikipedia.org/wiki/Integrated_electric_propulsion... and

Very few, if https://en.wikipedia.org/wiki/Integrated_electric_propulsion#List_of_IEP_ships https://en.wikipedia.org/wiki/Integrated_electric_propulsion... and https://en.wikipedia.org/wiki/Columbia-class_submarine#Electric_drive https://en.wikipedia.org/wiki/Columbia-class_submarine#Elect... are to be believed. The latter claims that as of 2013 there is exactly one nuclear submarine class (https://en.wikipedia.org/wiki/Triomphant-class_submarine https://en.wikipedia.org/wiki/Triomphant-class_submarine to be exact) that uses electric engines.