"Communists were first to space, no wonder they are first to master glorious power of fusion."
Fusion Plants are the 11th generator in the Land industry. The land cost only takes about twice as long to reach than Bombers, Sky Farms, and Laser Drills with the same researcher levels, but they take a lot of comrades to unlock, like Laser Drills, and have the same generator cost of 100 CC. The first mission requiring fusion plants is on Rank 113.
Fusion plant missions grow very slowly for about 30 ranks after introduction, not reaching the billions until Rank 139 and the trillions until Rank 142. However, multi-day comrade missions start appearing after that, growing to 50 T at Rank 148 and 61 T at Rank 150, requiring multiple weeks' worth of comrades even with Earth Wyrm Jym and comrade rares maxed for players who choose to do these missions. Post-fusion plant land missions also increase very slowly, from 1.4 GGGG at Rank 114 to 32.1 JJJJ at Rank 150, meaning players who have strong production in the land industry will be able to complete these missions with just Tube Travels on ranks without fusion plant missions.