Tekkit Classic Nuclear Reaction Automation

I have a basic reactor with a energy condenser pumping ice in to the last row (minus the first and last slot in the row). How do I automatically pull out depleted cells and replace them with uranium cells BUT not fill in the slots with ice? My problem is that the filter pulls out ice and fills them in slots where uranium cells should be.

Factorization's Router is able to fill one predefined inventory slot. You can use one for each inventory slot that needs to be filled. That means this solution is a bit expensive.

Another solution i can think of would be ME import export buses controlled by a Computercraft program. You would first activate one import/export pair, wait a little bit, then deactivate the first and activate the second pair. Repeat. This has the disadvantage that if you are filling ice in the moment the uranium cells have disappeared, you still end up with ice in the wrong place. Using the computer to sense when a replacement is needed, it should be possible to avoid this problem.

Disclaimer: I only know Tekkit-lite, so if one of the mods is not in tekkit, ignore that part of the answer.