Explosion may have occurred inside vessel of Fukushima Unit 1 — Can generate missiles that endanger containment integrity

Published: October 16th, 2012 at 6:37 am ET


The SimplyInfo research team discusses a possible explosion inside Unit 1’s vessel:


From this NRC document, the existence of damaged concrete debris is explained:

“the case that the containment has many sub-compartments, a local deflagration or detonation may occur that damages the sub-compartment and through this may generate missiles (concrete blocks from the disintegrated compartment walls) that can endanger the containment integrity. … The resistance of a concrete containment to such objects is larger than that of a steel containment: upon impact, the missile may generate cracks rather than gross failure.”

Explosive events are known to be possible inside reactor buildings, inside containment structures and inside the reactor pressure vessel. Unit 1′s accident progression was rapid. By the early hours of March 12th, 2011 radiation levels were rising in the turbine building of unit 1. At the point unit 1 lost cooling the meltdown took place in less than an hour. This would also cause the rapid build up of hydrogen as fuel melts. The hydrogen explosion of unit 1 could have occurred in locations beyond just the refueling floor. This would explain the charred appearance of the containment structure and possibly some of the damage found inside so far.

Workers were able to briefly obtain some pressure readings in unit 1, The recordings show pressures close to, but not exceeding, the setpoint of safety/relief valves. Intriguingly, there is no evidence that safety/relief valves opened. This lack of pressure buildup in the reactor vessel indicates either the pressure indicators were not working properly or there was already an opening in the reactor vessel allowing pressure to escape. There has long been an assumption unit 1 suffered from a LOCA (Loss of Coolant Accident). […]

[…] In the case of a LOCA fuel is uncovered, interactions and fuel melt,  maximum hydrogen generation and a possible detonation in vessel are possible. A pipe break low enough in the vessel which would still allow fuel melt but trap the hydrogen in the reactor vessel, especially if the safety relief valves don’t lift could create conditions where an in vessel hydrogen explosion could happen.


See also: [intlink id=”nrc-suspected-detonation-at-reactor-no-1-weeks-before-gundersen-postulated-such-a-scenario-at-no-3″ type=”post”]{{empty}}[/intlink]

Published: October 16th, 2012 at 6:37 am ET


Related Posts

  1. “Impossible” that bulk of melted fuel is in Unit 1 containment — Charred vessel could indicate explosive event inside October 15, 2012
  2. Kyodo: Water at Fukushima Unit 1 is more radioactive OUTSIDE containment vessel than inside October 12, 2012
  3. New footage inside Fukushima Unit 1 containment vessel — Thick steam, blackened piping (PHOTOS & VIDEO ) October 10, 2012
  4. “Very Unexpected”: Large debris filmed in Fukushima Unit 1 shows something explosive happened inside containment (VIDEO) September 27, 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

7 comments to Explosion may have occurred inside vessel of Fukushima Unit 1 — Can generate missiles that endanger containment integrity

  • harengus_acidophilus

    Diggin' in the past?

    What is the use of a detailed desciption of this ongoing accident?
    Who need this? Mankind or nuke industry?

    Today we need an idea how to "fix" (I know about the impossibilities) this situation. Detailed research about the early stages of this accident… maybye reactor designers need this.
    The use nuclear "energy production" must end!

    In my opinion the focus must be the future, not the past.

    Additional… from a global view, fuku will have ongoing worldwide implications and maybye leeds to the extermination of all life on this planet if we (all human beeings) can't contain this ongoing releases of radioactivity.
    Did you really think, the sinkhole story is in the same global category, or is it a more "local" (also a hole continent is local compared with global)…?

    I'm not sure.

    On the other hand: open discussion about the dangers of energy "production" maybye can change the mindset of "Joe Sixpack".

    And -with no regret- from the european sight:
    You americans screwed your by a genocide stolen land.



  • Radio VicFromOregon

    I think this is one very likely version of what happened in Unit 1. If this is true, then that changes the whole decommissioning plan for this reactor. I think a steel and concrete/boron sarcophagus will be the only possible route. Venting hasn't dropped the heat or the radiation. Number 3, as well. So, instead of trying to save face and look like some kind of normal decommissioning plan will work, let's hope TEPCO can refocus its attention on encasing these two, at least, and start working on the underground boron lined trench Arnie Gundersen spoke about that needs to be dug beneath the entire site to keep the coriums from reaching the groundwater. Oh, and, the double-lined pool just beneath the Unit 4 in case the SFP 4 collapses. Then get to work on patb2009's lead transport sling for the broken fuel rods. Times a wasting and these figures and this article prove it.

  • patb2009

    kind of late to trench around the site, the corium has burned to a homeostasis with the local environment, IMHO.

    all we can do now is try and dump the fuel pools.

    • PhilipUpNorth PhilipUpNorth

      Agreed, patb2009. Though it would be kind of nice to stop the highly contaminated ground water from getting into the Pacific Ocean.

  • bluebonnet bluebonnet

    There's a new diary on Daily Kos about Unit 1, entitle " Radiation probes indicate NO melt through at Fukushima Unit 1.

    The diary and many of the comments minimize the situation. If anyone is a member of Daily Kos they might want to add a comment and invite people to visit here. Thanks

  • astute

    Muahahhaha! Caught in their own lies at Daily KOS! TEPCO info contradicts the "AtomicKnights" 'info' TOO FRIKKEN MUCH! Nuke Industry PLANTS are on BBs…. too obvious BEWARE

  • astute

    it says in the article on NUKE INDUSTRY Blog "Atomicinsights.com" that Rod Adams is a pro nuke apologist/propagandist! again caught in their own lies; so much for the "truth" or a balanced viewpoint