4.2 tones of highly contaminated water leaked on the first floor of reactor4. It contains 77,000,000,000 Bq/m3 of cesium.
Around 11:15 of 8/14/2012, a nuclear worker found the contaminated water leaking in one of the rooms on the first floor of reactor4. (1cm deep, in a room of 350 m2)
Tepco explains it was from the pressure hose to drain the contaminated water in reactor3. It didn’t leak out of the reactor building supposedly.