TEPCO is sending 11 TEPCO employees and one robot (Survey Runner, which looks like a smaller version of Quince and has already gone inside Reactor 2's Torus Room in April this year - photo, video) down to the basement of Reactor 3 to survey the inside of the Torus Room. Planned radiation exposure for the human workers is 8 millisieverts.
No information of how long each worker will have to stay there to assist their robot co-worker. They won't go inside the Torus Room, as the very high radiation levels are expected inside. Instead, Survey Runner will go. The human workers will carry the robot through the narrow passage in the basement to the Torus Room door, which they will open for the robot.
8 millisieverts of radiation exposure. Before the Fukushima accident, it was rare even for the nuclear plant workers to get 1 millisievert exposure in one year. Now, the workers may get 8 years' worth of radiation in a day's work at Fukushima I Nuke Plant.
When the workers tried to enter the Reactor 3 Torus Room in March this year, the access door was warped and didn't open. The workers didn't stick around to open the door, because the radiation levels were probably too high for the work (it was 75 millisieverts/hour in front of the door). TEPCO sent workers again in June to measure the water level in the basement.
From TEPCO's handout for the press, 7/10/2012:
Purpose: As water leak investigation and water stop measure implementation are planned for the area from PCV / Reactor Building to the Turbine Building, it is critical to understand the current condition of the Torus Room. A robot will investigate the inside of Torus Room with high radiation dose to obtain inputs to be leveraged for planning the water leak investigation and water stop measures.
The following will be done in the Torus Room in Unit 3 Reactor Building basement.
-Visual confirmation (Acquire photos and moving images)
-Dose rate measurement
-Collect sound samples in the Torus Room
Equipments: Remote control robot (Survey runner)
Members involved: 11 TEPCO employees
Investigation date: Wednesday, July 11, 2012
Planned expose dose
8 millisievert: 6 Carrying the robot through the triangle corner, opening doors
2 millisievert: 5 Robot operation, preparation
*Robot operation control is done in Unit 3 S/B (0.1mSv/h)