This script for CraftTweaker introduces Hydrogen, Tritium, and Deuterium from Mekanism into the NuclearCraft mod's Fusion Reactor. The output will give you NuclearCraft fluids. All values are the same including fuel time, Base RF, and Heat Variable.
NOTE: This feature was implemented after TurboDiesel saw this script. Those using NuclearCraft-2.10h--1.12.2 or newer do not need this script. https://minecraft.curseforge.com/projects/nuclearcraft-mod/files/2552538