https://pastebin.com/aJgPwiFD
In case this helps, it worked fine before updating Reika's mods to V23a. I didn't feel like reporting it to Reika as the crash log doesn't mention any of his mods.

Hey there - I don't know what is causing this, but I'm afraid I'm not supporting the 1.7.10 version of the mod any more.

I guess I will just have to keep on using V22d of Reika's mods then.

V23b of either RotaryCraft, ReactorCraft, or DragonAPI fixed this issue.

Nice :)