Unit 1 Access Hatch Inspection Gives Clues

TEPCO sent a pair of robots in to inspect the personnel access hatch for unit 1 recently. Upon reviewing the video we found a few things of significance. TEPCO obviously had some motivation for checking this room. A large diameter steam pipe runs through the adjacent room and goes through the thick concrete containment wall.

The pipe is a steam line for the HPCI system. The radiation levels near the pipe jump to a range of 120-155 mSv/h and water can be seen on the floor. Salt staining is also evident below the pipe leading to a floor drain. This drain could be part of a controlled liquids system meaning that water running to the drain may be captured by radioactive waste systems at the plant. The leak appears to have been going on for an extended period of time and a portion of the leak begins at the containment wall. It also appears the leaking water was somehow related to the water injected into the reactor due to the salt content.

The HPCI system at unit 1 was never used. TEPCO claims water levels remained above the level that would have turned on the HPCI system before the tsunami. After the tsunami the TEPCO cites DC power was not available rendering the HPCI control systems out of service. fukuleaks.org/web member Peter Melzer explains in more detail, the events at unit 1 related to the HPCI system. Some questions remain about the nature of the HPCI failure at 1 and why it did not automatically operate at certain points.

Other evidence of note in the inspection is the blistering of the floor. Whatever material had been used to cover the floor cracked and blistered with more seen closer to the containment wall. This could have been caused by extreme heat or steam. The access hatch itself shows signs of high heat, the paint appears slightly burned and cracked. A small mark on the floor beside the hatch shows some sort of burn mark.
The full gallery of our video stills for this inspection can be found here on our Flickr Page

These findings do not give an immediate explanation for an event during the meltdown but they are important and may explain more when combined with other information yet to be found. .

HPCI steam pipe where it enters 1st floor into basement. One of the buckles for the insulation covers has come undone. Possibly due to movement or vibration of the steam pipe.

 HPCI pipe & penetration cylinder that goes into the containment wall.

Standing water and staining below the cylinder near the floor drain.

Leakage from containment wall and what appears to be salt buildup.

Floor drain and standing water below the HPCI steam pipe.

Access hatch discolored orange paint and possible burn mark on the wall to floor junction.

Another section of the steam pipe insulation with a buckle undone.




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