“Very Unexpected”: Large debris filmed in Fukushima Unit 1 shows something explosive happened inside containment (VIDEO)

Published: September 27th, 2012 at 1:38 pm ET


Watch the video here

The SimplyInfo research team provides an analysis of the newly released footage from inside the Unit 1 containment vessel at Fukushima Daiichi:


They took a brief look inside containment and found some rather unexpected large debris inside.

This was very unexpected as the containment inspections of unit 2′s containment showed no big debris, just bubbled paint and some small flakes of unknown origin.

These debris pieces were found in unit 1 containment above the 1st floor grate and appear to partially consist of metal that has a shiny appearance. The hydrogen explosions in the reactor buildings are assumed to have happened outside of the containment structure in the reactor buildings. TEPCO has claimed the hydrogen leaked back into the refueling floor during the venting attempt. This large debris inside the containment of unit 1 shows something explosive happened inside containment at some point.


The conditions inside the unit 2 containment and torus room and also the unit 3 torus room show a completely different set of conditions compared to unit 1. Exactly what this means is not clear at this time. As we know more or determine what may have happened at unit 1 we will release a new report.


Published: September 27th, 2012 at 1:38 pm ET


Related Posts

  1. Watch: New Large Debris Found In Unit 1 Containment (PHOTOS & VIDEO) October 17, 2012
  2. “Impossible” that bulk of melted fuel is in Unit 1 containment — Charred vessel could indicate explosive event inside October 15, 2012
  3. Gundersen: Video inside Reactor 1 may show seismic damage — Japanese experts suggest unit was having severe problems before tsunami September 27, 2012
  4. New footage inside Fukushima Unit 1 containment vessel — Thick steam, blackened piping (PHOTOS & VIDEO ) October 10, 2012
  5. Yomiuri: Video believed to show parts of internal structure in Fukushima Unit 1 containment vessel scattered around — 3-inch-thick lead plate disappeared (DIAGRAM) September 29, 2012

8 comments to “Very Unexpected”: Large debris filmed in Fukushima Unit 1 shows something explosive happened inside containment (VIDEO)

  • patb2009

    honestly the bright metal looks like shredded aluminum or coated steel from conduit.

    Perhaps the explosion occurred in some of the conduits and blew shredded bits of tubing everywhere plus cracking large bits of concrete off of passthroughs in the concrete.

  • Dr. Anne Lee Tomlinson Maziar anne

    The article linked isn't about Unit#1, but Unit #3:

    Unit 3 Debris Accident & Pool Damage
    September 27th, 2012 |

  • PhilipUpNorth PhilipUpNorth

    I am mystified by what I see in this video. I believe the view is down, and we should be able to view the floor grate under the surface of the water. But instead, I am seeing a series of small pipes. If the camera were aimed up a bit, I would expect to see the Reactor Shield Wall straight ahead of the punch-through hole. I am having trouble getting my bearings. Can somebody please tell me what we're seeing here?

    Also, there are none of the light flashes we see in videos inside containments. I agree with anne: this is not a video of a reactor, but instead must be a video of SFP3.

  • moonshellblue moonshellblue

    I think Anne meant that she was linking to a video of Reactor 3 but anyway I'm not sure what we are seeing but obviously TEPCO thinks it is rubble from an explosion. We know the core melted through the containment vessel and I would imagine at those temperatures it could rupture just about anything. Also you have to take into consideration how close these plants are to each other thus the explosion at 3 and 4 could have possibly caused damage. Who knows but I sure don't see any signs of the core. What a mess.

  • PavewayIII PavewayIII

    Look at the TEPCO handout first to get oriented:


    Then look at or download the video:


    The correct SimplyInfo article (Unit 1) is here:

  • moonshellblue moonshellblue

    is it possible an underground explosion happened caused by the corium? I remember TMI had an explosion and I believe it was in the containment vessel but I could be mistaken and TMI was a hydrogen explosion. Not sure what this could be but there is still smoke or steam remaining which could mean it is a recent event possibly. I'm just guessing. Any other thoughts?

  • TMI2's containment "vessel" was that very large concrete dome structure indicative of a PWR (but not a BWR such as those at Daiichi). That structure contains the reactor vessel and two (four in one design) steam generators as well as associated piping and equipment. It's HUGE (the SGs alone are three stories tall, The pipes can be 9 feet in diameter.

    There was more than one hydrogen explosion, the biggest of which pegged (and broke) the containment atmospheric pressure gage at 32 psig. Containment atmosphere is normally kept at a negative 3 psig, making the relative pressure differential between the aux building and containment interior about equivalent to that of an airliner at 30,000 feet. Workers must enter through an airlock. 32 psig is a big explosion, really.

    TMI2's containment held the "pressure spike," though it didn't (and wasn't designed to) contain the radioactivity that escaped to the RCS [Reactor Coolant System]. The Fukushima containments were all much smaller, entirely surrounded by the industrial buildings we've all seen in absolute rubble after their explosions. None of the containments 1, 2 or 3 held – all were severely breached early on.