IRSN (France) (pdf): Water temperature in the [spent fuel pools] increased, sometimes to the boiling point. […] The most notable point is without a doubt the impact of hydrogen explosion on the SFPs. Overall, it appears that the pools resisted the hydrogen explosions but a significant loss of leaktightness in the pools and dewatering of the fuel assemblies may have occurred, seriously aggravating the situation in terms of radiological conditions at the site and releases into the atmosphere.
Asahi Shimbun, Feb. 6, 2014: The Nuclear Regulation Authority said Feb. 5 it instructed Tokyo Electric Power Co. to reduce radiation exposure among workers who are removing spent and unspent fuel from a reactor building at the Fukushima No. 1 nuclear plant. The NRA issued the instructions after it started studying radiation levels around the work site on the fifth floor of the No. 4 reactor building in December. NRA officials said they found high levels of radiation emitted from cobalt-60 that was apparently mixed with shavings produced when workers cut into reactor components inside the storage pool there. [...] The NRA found that the use of lead plates on the floor [...] reduced the radiation levels [...]
The NRA says the high radiation levels are from Cobalt-60 ‘shavings’ produced by workers… yet the chart above from a NRC FOIA document (pdf) indicates Co-60 readings were nearly 17,000 Bq/liter just a month after 3/11.
Published: February 11th, 2014 at 4:39 pm ET