It was announced on January 17 that boring a hole in the Containment Vessel of Reactor 2 at Fukushima I Nuclear Power Plant was successful.
According to NHK News, it took 10 teams of workers, 4 in each team, who had been trained on Reactor 5 as a "mock-up". They received maximum 3 millisieverts radiation for their effort. No information of how long the work lasted.
Some people in Japan watching the NHK News reporting the event wondered, "Whose endoscope is it?" It turns out, most likely, that it is made by Olympus, of "cooking the books" fame.
First, NHK News (1/17/2012). The video clip of the news is at the link for now. (NHK News links are one of the shortest-lived among the Japanese media, on par with Yahoo Japan News.)
On January 17, workers at Fukushima I Nuclear Power Plant bored a hole for the endoscope that would be inserted inside the Containment Vessel of Reactor 2 to survey the condition inside the Containment Vessel for the first time since the accident.
At Fukushima I Nuclear Power Plant, the condition of melted fuels in Reactors 1, 2 and 3 and the condition inside the Containment Vessels are not yet known. The information is vital to the future decommissioning work and to the stable cooling of the reactors.
TEPCO has decided to use an industrial-grade endoscope that can operate under the high radiation and survey the condition inside the Containment Vessel of Reactor 2 and measure the temperature. On January 17, as a preparation for the survey on January 19, workers entered the northwest corner of the 1st floor of the reactor building and bored a hole at a location on the Containment Vessel where pipes would be inserted [as necessary?].
The work was done by 40 workers in 10 teams, with each team consisting of 4 workers. According to TEPCO, they had been training on Reactor 5 as a mock-up exercise in order to complete the work in a short period of time. Reactor 5 is the same type as Reactor 2. The radiation exposure for the workers for the January 17 work was maximum 3 millisieverts. Now that the work has been successfully completed, TEPCO will proceed as scheduled, inserting the endoscope on January 19. If successful, Reactor 2's Containment Vessel interior will be viewed for the first time [since the accident].
Here's at the Olympus site: