Kyodo News has reported that a camera lowered into the Fukushima Daiichi Unit 3 high-level radioactive waste storage pool has revealed that a 35 ton piece of equipment used to transfer irradiated nuclear fuel into and out of the pool fell in, most likely due to the massive hydrogren explosion which rubblized the reactor building in the earliest days of the catastrophe in mid March 2011.

"Heavy load drops" can punch holes in the sides or floors of pools, draining the cooling water away and causing a high-level radioactive waste fire. The U.S. National Academy of Sciences in 2005, Robert Alvarez et al. in 2003, the U.S. Nuclear Regulatory Commission in 2001, and Brookhaven National Lab in 1997 have long warned about such risks. The NRC study reported that 25,000 people could die of latent cancer fatalities up to 500 miles downwind of a pool fire. The Brookhaven study warned of the potential for 143,000 deaths.

No explanation is given for why it has taken Tepco 13 months to reveal this information. There is growing concern about the Unit 4 pool collapsing, but as this article shows, Unit 3 is also at risk -- there is a lack of even basic information about its status, condition, and structural integrity.