Following the grudging approval from Nuclear Regulation Authority, the construction of the frozen soil impermeable wall around the reactor buildings and turbine buildings has promptly started.
The first place that the contractor (Kajima) started to drill holes in was the northwest corner of the wall right near the Reactor 1 building.
The frozen soil wall plan by Kajima has been criticized by the media and net citizens as "untested" and "costly". I don't personally share much of that sentiment after looking at the presentation by Kajima and those by two competitors (see my post from May 30, 2013), but I do worry, as the modus operandi of TEPCO is to cut cost by any means. I have a nagging feeling that TEPCO will manage to sabotage Kajima's work somehow.
From TEPCO's photos and videos library (6/2/2014):
An aerial photo by Yomiuri (how they got away with taking a picture is a mystery to me, given the warming from the government/TEPCO on the physical protection) shows how close the wall would be to the reactor building (Reactor 1, in this case). The drilling location is marked with a red circle:
The exhaust stack you see on the right has a spot where the dosimeter went overscale at 10,000 millisieverts/hr (or 10 Sieverts/hr) back in August 2011. TEPCO did calculate how high the radiation might be in November 2013, and it was at least 25 Sieverts/hr on the surface of the pipe. Ambient radiation levels near the pipe range from 19 to 95 millisieverts/hr.
TEPCO's survey map on March 23, 2011 made public for the first time outside TEPCO shows the area with the radiation levels between 6 to 130 millisieverts/hr:
After painstaking removal of highly radioactive debris that littered the location by human workers and remote-controlled heavy equipment, the radiation levels as of May 14, 2014 are mostly between 0.2 to 0.8 millisieverts/hr. The level near the drilling location looks to be 0.35 millisievert/hr:
Still, 0.35 millisieverts/hr is 350 microsieverts/hr; it is nowhere near the level for workers to work without concern for radiation exposure. Three-hour work on that location, and you may exceed 1 millisievert per year excess radiation exposure.
In Fukushima City today (6/5/2014), the radiation levels are mostly below 0.25 microsievert/hr, according to Fukushima Prefecture radioactivity measurement map:
In Tokyo today, a monitoring post in Shinjuku shows the level at 0.0343 microgrey/hr, according to Tokyo Metropolitan Institute of Public Health. It is back to the level before the nuclear accident. At 1 meter off the ground, the radiation level is 0.06 microgrey/hr: