Things you could try:
Connect the reactor to a mfsu with glass cable. Don't put it next to your reactor, the mfsu can output a redstone signal under certain conditions. Then have a look if it still stops working.
If that does not work, then try placing the reactor somewhere else. There was a bug that the reactor won't work properly if it is placed directly on a chunk border if the reactor is in one chunk and a chamber in another chunk. No idea if that was fixed.