ead about the guy who had problem with chunkloader and a builder.. i had the same problem when trying to copy stuff from the overworld to the rtf dimension the other way works fine (or at least move).. . this while using chunkloaders(chicken chunks) in both relams..

too the real problem.. im using direwolf20 modpack version 1.5.0 includes rftools 3.10
im gonna copy/paste my post from the FTB forum:

Involved mods: RFTools and Big Reactors

So i had a nice base setup and everything was fine.. checked direwolfs tutorial on rftools and got the idea to use it to make a Void dimension and use the space chamber and builder to move my base to the void world.. said and done..
but yesterday i was building in my new void base and checked my 31x31x3 big reactor if it had fuel and for some reason it had eaten trough a full iron chest of yellorium and had only about 50% fuel left.. but the "waste" iron chest had 4 stacks of cyanite.. WOOT?

now it has happened like 20 more times and im gonna move my base to a mystcraft void world instead.
i've tryed to repeat it and i've found a way.
everytime i step out from the dimension or logoff and get back in.. the yellorium in gone..
tryed a normal chest, same shit. tryed enderio's item conduit, thermal dynamics item duct, same shit..

so yellorium has a habbit of disappearing in the rftools dimension..

but for fun i checked another chest containing shit from a mining laser and to my supprice it wasent empty.. so my guess is that it has something to do with the flow of yellorium at the (re)loading of the dimension.

and did i have this problem in the "normal" world.. NO!

EDIT: checked if the reactor would lose fuel already in it when i leave and enter the area again. and it dosent.. but when i leave fuel in the chest, the "fuel" lvl change in the reactor as the ingots disappear, mostly going down..

And a chest with yellorium that isn't connected to any item ducts or item contuids keeps the yellorium.

this was a my post on FTB forum.. but my guess is that this means that big reactors also get uneffected by chunk loaders. Ive moved my base to a mystcraft age but i really hope that this problem will be fixed because i really want that rtf dimension as my home but cant use it just because of the problem. and if i find anything else ill post it, like the mod! great work!

This is something that cannot be the cause of rftools dimensions. Big Reactors is consuming fuel entirely on its own. RFTools has nothing to do with that and wouldn't even be able to affect that. If Big Reactors has a bug where it has fuel disappearing if you enter/leave an RFTools dimension then that's a bug in Big Reactors and not in RFTools.

Anyway, in my own survival world I have a big reactor in an rftools dimension and I don't have that problem.

But note that fuel disappearing after moving it with the builder is a known issue. That has nothing to do with rftools dimensions however.

Closing due to lack of information and inability to reproduce