The stainless pipe that circulates water for the condenser unit for the Spent Fuel Pool of Reactor 4 has been found leaking. The amount of radioactive materials in the water (coming out of the SFP) is very low, says TEPCO, only 10 becquerels/liter. It is a very minor drip, of one drop in 30 seconds or so, according to Mainichi Shinbun (in Japanese; 8/23/2011).
TEPCO's countermeasure is to put a bucket under the dripping pipe. The cooling operation continues uninterrupted.
TEPCO's handout for the press on August 23 is still only in Japanese. I put the green circle around the leak location:
