Old school fusion reactors:
Name:  2016-02-15_22.11.11.png
Views: 40
Size:  319.4 KB

Name:  2016-02-15_22.11.34.png
Views: 40
Size:  167.6 KB

Now check the Minecraft version:
Name:  2016-02-15_22.11.48.png
Views: 40
Size:  367.4 KB

It's not GregTech. Someone is porting GregTech 4 stuff to Minecraft 1.8.9