Replaces the Fusion Reactor with an equally powerful RTG (radioisotope thermoelectric generator).
Mods introducing new content into the game.
Armors or armor equipment.
Simply disabled Fusion Reactor causes many problems in other mods those requires that as a crafting ingredient.
Here is a right way to delete old items: just disable the recipe and delete the recipe from technology. https://forums.factorio.com/viewtopic.php?f=25&t=56027
Version 0.2.0 has the fusion reactor fully replaced with the u235 rtg.