10+ sieverts per hour means there is direct exposure to fuel rods: Australias former top radiation official August 2nd, 2011 at 10:58 AM Record-high radiation detected at Fukushima, The World Today (ABC Australia), August 2, 2011:
Peter Burns, former chief executive officer of the Australian Radiation Protection and Nuclear Safety Agency
The levels reported of 10 sieverts per hour are very high levels and its going to be very difficult to manage workers going into those areas and doing operations. 10 sieverts is actually a lethal dose of radiation. So you cant afford to be exposed for more than a few minutes at those levels. It means youre directly exposed to fuel rods in the reactors or the spent fuel ponds very closely and while its possible to get to those levels it means there is very little shielding going on there.
See also:
Paper: TEPCO needs to check if high radiation is spreading Two more spots appear to be above 10 sieverts per hour, but no plans to actually take measurements Tepco: Ultra-high radiation levels may be from melted fuel that leaked out of containment vessel (PHOTO) NYT: Fatal Radiation Level Found at Fukushima Exceeded 10 sieverts per hour, measuring device was maxed out Highest radiation level since the start of the nuclear crisis: 10 sieverts per hour measured outside between React