1. Most BWRs of that vintage have metal siding for walls at the top elevation, since there’s nothing essential on the top elevation that needs protection. Looks like the siding was blown off but the concrete structure below it containing the essential things is intact.
    There’s typically no way to accumulate hydrogen up at that level, so a explosion from the turbine generator hydrogen cooling system sounds plausible.
    Generator hydrogen is kept inside by a seal made of pumped oil at each end of the generator shaft. The oil pumps have a battery backup (to prevent this sort of explosion), but those batteries can’t last forever. When the pumps stop, the hydrogen escapes. This design is used in nearly all fossil and nuclear plants.

    1. Looks to me like the Rx building went. Explain to me how generator hydrogen gets into the reactor building. Is the turbine in the same building?

      1. Turbine is in a separate building. Either the turbine explosion blew the siding off the adjacent building, or some strange process got the hydrogen into a building where it normally doesn’t exist.

    2. Appears that they lost the Reactor Building. Picture is not that clear but based on other pictures they have a lot siding, unlike VY. I can’t tell from the picture what the integrity of the Spent Fuel Pool is, but that would be a concern considering the severity of the explosion that occurred

      1. Correction, later pictures indicate that the RB is standard design. They lost the siding at the top 3rd which would be expected based on the type of explosion they had.

        1. Jim,
          You are correct. Only BWR 6, ABWR, and ESBWR, (with the exception of hope creek BWR-4) have steel reinforced reactor buildings over the refuel floor elevation. The part of the reactor building (better to call it secondary containment for BWR) at the refuel floor elevation and above is really nothing more than industial siding. It will blow out with an overpressure of less than 1 psi. what is disconcerting from the single enlarge picture of the explosion from the earlier comment is that the reactor building overhead crane collapsed and fell onto the refuel floor of Fuku-1. I would be very concerned for the spent fuel pool.
          No way that hydrogren came from the main generator. My opinion is that Fuku-1 did a manual vent of the primary containment to the secondary containment to relieve primary containment overpressure condition (reported to be well over the primary containment design pressure). Unknown to me if they realized that they had significant H2 generation from the core. It is possible that they vented to the secondary containment planning to then filter the release throught the standby gas treatment system once they got some AC power back. (this is all speculation on my part). Also it appears that they never installed a hardened primary containment vent backfit in US BWR Mk I containments per NRC GL 89-16.

  2. Those pictures at 0:33 – 0:45 on the video are burning LNG holders. That is extraordinarily dangerous, but it’s nothing to do with a nuclear plant – those are pictures of the fire at the refinery.

  3. They are conflating an oil/gas refinery or storage complex with a nuclear reactor.
    And why not – it makes great video and keeps the suckers coming back for more “information”. Increases ratings and pays the bills.

    1. Yes, I heard this guy speaking a few minutes after the explosion on Fox News. The one time I wish they’d have a little bias, they invite a Liberal tool to be the expert. No offense to pro nuke liberals…
      He quickly went into the China Syndrome as the worst case.

    2. He is no nuclear weapons expert. The people who are the real experts don’t get on TV and talk about it.

    1. BTW, note the elevated spent fuel pool in the upper right. That’s exposed to the environment now. And what is cooling that with no diesels for the spent fuel pool pump motors?

      1. If spent fuel pool is intact this is the least of their worries. All they will need to do is provide makeup to the pool. Preferably freshwater rather than seawater.

      2. If it’s exposed, they could just fly water in, somewhat like they do for forest fires. I honestly don’t know; I’m no BWR expert either. It was just a random thought…

  4. Prediction: If Japan shuts down its entire nuclear power industry, and replaces only 50% of the electricity lost with coal-fired power, the extra radiation emitted DAILY will exceed the entire radioactive release as a result of the Fukushima accident.
    That having been said, this incident, and the Japan nuclear industries substandard safety practices and preparations, point up the need for replacing older reactors with newer designs, preferably LFTRs, which operate at atmospheric pressure and can be passively cooled without the need for an independent power supply.

  5. As others have pointed out, those tanks are the storage tanks at the LNG facility.
    Not surprised they are using video of the LNG plant burning to the ground since reporters always assume a hyperbolic cooling tower must mean a nuclear plant. When telling a story why let strict adherence to the facts stop someone.

    1. Reporters? Even calculus and trig teachers think only about nukes when we are talking about hyperbolic functions. It pisses me off.

  6. My guess is that water reacted with the fuel cladding at high temperature to release large quantities of hydrogen in the reactor cooling system. The resulting pressure lifted the reactor vessel relief valves venting the H2 into the reactor building. The mixture was ignited by some source inside the building.
    In my opinion it was a big mistake to allow a large volume of explosive mixture to accumulate in the building. There is a range of fuel air concentrations that is flammable. The velocity of flame propagation depends on concentration, and is very slow at the minimum flammable concentration. The intensity of the blast indicates a large volume of fuel air mixture near the optimum fuel air ratio for high velocity propagation.
    The explosion could have been prevented by;

    1. Undoubtedly you are correct and the actions mentioned would have been desirable. But if you have no power and pressure in the drywell has exceeded 100 psig what would you do? Easy to suggest actions that are not achievable.

      1. What would I do? Jim, if each plant had a containment vent filter designed for accident conditions I would vent the containment through the filter. No active systems required.
        For this situation I would install ignition devices near the containment vents of any other reactors in danger of fuel damage due to lost cooling water. If radiation levels or hydrogen concentration is too high already I would vent the reactor building through the turbine hall, using the turbine hall vent fans to draw air out of the reactor building. It may be necessary to create a hole in the opposite side of the reactor building to let fresh air enter the building.
        I would run the fire protection sprinklers in the turbine hall. This would wash out most harmful nuclides and avert an explosion. Sprinklers and fans do not require a great deal of power. Portable industrial generators could do the job. Not a great solution, but much better than another explosion.

    2. Bill, you are conflating the building with the containment. At a PWR they are the same entity. At a BWR, they are separate/discrete entities. The BWR containment doesn’t have a relief valve, someone has to intentionally open a valve to depressurize it. BWR containment is already inerted (the building is not, since people have to work there). Leakage from containment s retained inside the building, and scrubbed thru HEPA/charcoal filters prior to release (assuming power is available to run the fans).

      1. Cpragman, I did not conflate the building with the containment. Read the last paragraph again.
        BWR containment should have a relief valve. A slow controlled leak rate is far preferable to containment rupture.
        Operators should maintain the pressure below design limits. If the core melts through the reactor vessel they should probably vent it down to atmospheric pressure to avoid a violent ejection if the containment melts through.
        When this is done there will probably be some changes recommended. Fortunately, next generation designs have largely addressed these issues.

    3. They did not lose containment, so it is not a shame. It is entirely possible that a relief valve lifted, and the hydrogen ventilated was a flammable mix, which ignited when vented, since it was then outside the inerted containment. So your suggestions #2 and the relief path could well have been followed, and the explosion resulted anyway – but in non-nuclear-safety portions of the plant; the secondary portion of the reactor building, exposing the underlying containment structure, still intact.
      Thanks for your post. It is good analysis, and mirrors some of the features that were undoubtedly incorporated into the original design and construction, even way back in 1970.

  7. The combination of the explosion, which NEI has indicated occurred in the secondary containment, and the decision to cool with seawater suggests that things are bad enough that they’ve decided to sacrifice the unit to prevent a worse outcome. Once the chlorides in the seawater get a hold of the materials in the reactor at those temperatures, I think they’ll never be able to explain away the potential for future stress corrosion cracking.

  8. Hey Rod, just a suggestion, but perhaps, since it appears that the verdict is in that this was the containment building, maybe you should change the subject line of the posting? Or, perhaps a followup post with a corrected headline? I realize you posted an update at the end of the article with the correction, but seems like the incorrect headline should not continue to proclaim an incorrect statement of the situation?

  9. Incredibly irresponsible of CBS, who is working in there newsroom. The pictures they are showing at the beginning of the broadcast are of a burning LNG plant! These people are incompetent. We really need competent reporting on issues like this.

  10. Rod – This is a time for pro-nukes to stick together.
    In the interest of pro-nuclear brotherhood (and out of no small amount of respect for the nation’s finest nuclear Blogger) I would like to pass along the following tidbit.
    Crows are currently a protected species under the 1936 the Migratory Bird and Game Mammal Treaty with Mexico which was additionally amended in 1972.
    Much as I am certain that you are fully willing, as a gentleman and man of your word, to go through with your promise to “eat crow” I advise caution. You should check with The U.S. Fish and Wildlife Service (USFWS) before predating and consuming crow to avoid breaking the law.
    There are just a few small out of the way restaurants that may be willing to serve crow (under the table) if your tip is large enough. If you cannot be swayed in your announced intension I might suggest a discrete inquiry at:
    The Crows Nest Restaurant Santa Cruz, California

  11. Rod
    The images in the CBS News video at the 36 second mark look like petrochemical tanks. I wouldn’t be surprised if the footage was from refinery or chemical plant fire.
    Thank-you for keeping up with the story. I will be checking your blog tomorrow.

  12. It would be nice to know greater detail about how the Zr cladding would interact with water to produce hydrogen as described in the NEI site. They put a few qualifiers in their statements so the bottom line right now is we still don’t know the whole story behind the explosion.

  13. @:36sec, this looks like a picture I saw Friday of a fire at a petrochemical plant (at least that’s what was reported when I saw it).

  14. That is a PetroChemical Plant and it is somewhat irresponsible that they are showing that video at that time when they are talking about a Nuclear plant. You are correct about Hydrogen being used for cooling of the Generator Set.

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