Board Thread:Questions and Answers/@comment-76.125.214.168-20130515044155/@comment-2158701-20140126122312

You could just mouse over the uranium cells. A brand new one lasts 10000 seconds in a reactor, and the damage value for it shows the number of seconds it's been used. Detecting it with an EU detector is a poor idea - for instance, an activated reactor connected to a filled MFSU doesn't output anything. There are many alternatives:

If you want to detect when the reactor has completed a cycle, try CCSensors. A sensor can detect the content in a reactor, and by, for example, monitoring for the number of uranium cells in the reactor, it would easily be able to tell when uranium cells are depleted. You will need to know how to program in Computercraft for this though.

Or you can use a filter with a near depleted cell in it that periodically pumps out, and is linked to an item detector. You can then use the redstone signal from the item detector to raise an alarm, trigger the loading system, etc. This is assuming you're using enough uranium cells that the chances of none of them leaving behind a near depleted cell is slim to none.

Unless you turn the reactor off constantly though, you really could just set a timer via Computercraft to 10000 seconds and have it output a redstone signal then.