There was a recent report that about a recent leak at Fukushima:
Last week officials from the Tokyo Electric Power Company announced that extremely radioactive water had leaked from a storage tank at the Fukushima Daiichi nuclear power plant….According to the utility over 100 tons of water containing 240,000,000 becquerels per liter of beta-ray emitting substances leaked out of the storage tanks over a period of nine hours before the leak was discovered. The water which leaked was largely partially treated water from early on in the disaster in March 2011….Alarms indicating a rise in water levels in the tank had gone off nine hours before the leak was discovered, but was ignored and shut off by workers who assumed that it had malfunctioned….TEPCO spokesman Masayuki Ono told reporters at a press conference that the radioactive water had leaked because three valves which should have been closed were open. At the time, Tokyo Electric speculated that one of the valves may have malfunctioned or have broken.
I did the arithmetic; this leak represents twenty thousand billion Becquerels of beta decay. It does not include alpha or gamma particles.
The workers are working under near impossible circumstances. The problems are attributed to human error and not the nuclear reactor technology itself. Maybe the nuclear reactors are simply too complex to be run by humans. After all, “to err is human.”