After the Japan Nuclear Energy Safety Organization (JNES) published its analysis that the water level inside the Containment Vessel of Reactor 1 at Fukushima I Nuclear Power Plant may be only 40 centimeters deep, TEPCO announced the plan to probe inside the Containment Vessel with the endoscope, just as they did for Reactor 2.
According to Jiji Tsushin, TEPCO plans to visually inspect the inside (by two endoscopic cameras), take temperature and radiation measurements, and collect the water samples near where the fuel debris (corium) is supposed to be on the floor of the Containment Vessel.
The fuel debris (corium) in the Reactor 1 is considered to have dropped to the concrete floor of the Containment Vessel and eaten into the concrete, as having been disclosed during the workshop organized by the NISA in November last year. TEPCO's estimate is about 65 centimeters into the concrete, and the Institute of Applied Energy's estimate is about 2 meters.
From Jiji Tsushin (part; 5/28/2012):
Toward decommissioning Fukushima I Nuclear Power Plant, the plan has been agreed upon to probe the interior of the Reactor 1 Containment Vessel using the industrial endoscope and collect the sample of highly contaminated water near the fuel debris for analysis. The work will be carried out sometime between late August and mid September.
The probe of the Containment Vessel interior was done on Reactor 2 in January and March this year, which revealed the water level to be only 60 centimeters from the floor of the Containment Vessel.
In Reactor 1, TEPCO will insert the camera and radiation survey meter through one of the spare penetrations for the pipes, and collect the contaminated water and analyze in order to estimate the condition of the melted fuel. After the probe, a thermocouple will be left inside the Containment Vessel [in the water] to continuously measure the temperature of the water.
The details of the Reactor 1 CV probe are in one of the reference materials (Japanese-only; pages 18 to 25) for the May 28, 2012 meeting of the Working Group for Medium to Long Term Planning. TEPCO will have to build a mock-up first to train the workers. (I'll post some of the pages here later.)