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Thursday, January 19, 2012

Boroscope at Fukushima Daiichi No. 2 inconclusive

TEPCO has completed the first examination inside any of the primary containment vessels at Fukushima Daiichi, using a boroscope inserted into No. 2 plant's dry well. Below is a graphic explaining the location, practiced a few days back at No. 5 plant.

Click the image to enlarge it. Below for perspective is an Oak Ridge National Laboratories illustration showing some of the same components from the side.

Of course, that image shows only the internals of the dry well and suppression chamber; below we can see these as they are positioned in the reactor building overall which will give new readers a better idea of what the first, overhead explanatory diagram was really showing.

Having shown all of this, we can proceed to the views TEPCO has released which are actually just video still frames. Nothing was determined by these views; the location and condition of fuel is unknown, as is the condition of the bottom of the reactor vessel and primary containment vessel. The views, TEPCO press releases, are labeled as to their location and in one instance as to elevation above sea level in centimeters ("OP 9500").

Some comments have been made in general media about apparent rusting of the drywell surface, which is possible - although it is also possible that some of what we are seeing here is the original color of anti-corrosion paint. See below - photo of three GE BWR plants under construction (TVA Browns Ferry Nuclear Generating Station) - note the color of the paint on the dry well exteriors:

As noted, TEPCO is no more sure of the condition of the lower end of the reactor vessel at No. 2 plant now than before. Further invasive attempts will be required to ascertain any sort of real estimate of the situation below the reactor vessel.

1:50 PM Eastern Thursday January 19, 2012

1 comment:

  1. I saw one article which concluded there was no water in the reactor. They didn't understand the difference between the drywell and the reactor.