Muon Scan Finds No Fuel In Fukushima Unit 1 Reactor Vessel

unit1_muon_2TEPCO published the results of the muon scan done by IRID and their cooperating partners. No fuel was found in the reactor vessel of unit 1 Fukushima Daiichi.

The handout in Japanese can be found here
A very rough English translation can be found here

This was as expected by many (including us) who have been documenting the other evidence that indicated this was the likely case. The plan for the future with unit 1 is to insert the shape changing robot in April 2015 to determine if the control rod drive rail is intact and an attempt to place the robot on the containment catwalk. If this goes as planned they could then use the robot to circle inside containment on the catwalk to collect more data.

Also noted on these images was the lack of detectable solid vessel in the bottom head area. The center lower section of the reactor vessel appears to be missing. The uniform dark outline of the reactor vessel is noticeably missing




The muon image below would show dark sections were there any fuel left in the reactor well. The vessel itself appears distinctly white. TEPCO admits in their handout that no fuel was found in the reactor vessel and that the planning towards fuel removal will need to be changed accordingly. unit1_muon

Also found was some evidence of fuel fragments possibly being relocated from the reactor vessel to the spent fuel pool and refueling floor. Earlier visual evidence shows the concrete reactor well cover was dislodged with the portion sitting up out of the well facing the spent fuel pool. This could indicate fuel debris having left the reactor vessel and containment vessel via the reactor well and fuel canal that connects the reactor containment and the spent fuel pool. If this is the case, it could complicate the debris removal on the refueling floor set to start this week.




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