Third Reactor at Fukuchima Dai-ichi Goes Into Meltdown

There has been another explosion at the stricken Japanese Nuclear Power Plant in the last hour or two. This is the third explosion in the reactor complex since the earthquake. The complex is made up of 8 reactors. By some reports, this one is by far the most serious explosion – with the fuel rods exposed, releasing highly radioactive material.

This video is from the second explosion -

http://www.youtube.com/watch?v=dytttMoivoQ&feature=player_embedded#at=155

New Explosion Rocks Japanese Nuclear Plant

An explosion that released radioactive material occurred in reactor No. 2 at the nuclear center at Fukushima, in northeastern Japan, on Monday.

The blast damaged part of the primary container surrounding the reactor’s core and caused an escape of an undetermined quantity of radioactive material, the Nuclear Security Agency said.

The Kyodo news agency reported that radiation levels in the vicinity “exceeded the legal limit” after the explosion, which occurred at 6:10 a.m. on Tuesday local time (2110 GMT on Monday), shortly after the Japanese government admitted that the reactor continued to be unstable after it suffered damage in Friday’s magnitude-9.0 earthquake.

The operating crew at the plant worked all night to inject seawater into the secondary containment structure in an attempt to cool down the core and prevent a meltdown that could emit radioactive material, but that did not have the desired effect and the reactor was not able to be stabilized.

If the nuclear fuel in the core begins to melt down, that would constitute an emergency situation of the highest order because of the potential for a severe radioactive leak that could contaminate the area.

Reactor No. 2 at Fukushima on Monday suffered a failure of one of the 10 valves associated with its cooling system, something similar to what occurred before reactors 1 and 3 at the same center exploded after the quake.

 

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4 Responses

  1. Mixed plutonium-uranium reactor in Japan loses coolant system as government evacuates 210,000 from area or quake-stricken nuke plant

  2. CNN put on “Bill Nye the Silly Science Guy” to proliferate disinformation to the masses. Nye said that “Uranium is a heavy metal — it looks like lead. If you get it too hot it melts.” Here’s the corrective for any of your readers that got bamboozled by Nye.

    WRONG. The fuel is in the form of a ceramic. It is pressed into small pellets. It is very stable. You could hit it with a torch and it will not melt. The pellets are loaded into a thin-walled special alloy stainless steel tube. There is a spring at the top that keeps the pellets compressed but allows them to expand. The fuel rod is electron-beam
    welded shut and decontaminated. Individual fuel rods are hot to the touch due to spontaneous fission but are relatively safe to handle.

    The rods are loaded into a frame that keeps them evenly spaced and provides room for the control rods. That also allows space for the coolant to flow.

    If the coolant level drops, the fuel rods will overheat. It is the SS tube that melts, and then the support structure. If all of the pellets were to drop down in a heap, it would be difficult to control the reaction. Seawater can physically cool the core to limit the extent of the meltdown, but you can never recertify that reactor and bring it
    up again. Building a new plant will take years.

    These are “slow neutron” reactors. The fissioning neutron cross-section of the fuel is — counter intuitively — much larger for slow neutrons. So you need some rods to bounce the neutrons around a bit and slow them down to optimize the criticality. So these reactors are not “a bomb trying to go off” while you are trying to keep a lid on it. It is extremely difficultto make a bomb.

    Consider the Three Mile Island disaster. What really happened there? We had a core melt-down and lost a reactor. But not much more. They purposely vented some pressure from the dome as a safety measure and that released some radiation. It was quickly dispersed by the wind and diluted down to background levels. I cringe every time they mention Chernobyl.

    Chernobyl was what I call a “Hibachi Reactor”. It was a stack of graphite blocks with holes drilled for fuel rods. Enrico Fermi’s CP-1 (Chicago Pile 1) was a stack of graphite blocks with holes drilled for fuel rods. They pushed the rods in and out by hand. Once you get a fire going in your hibachi it is very hard to put out because the nuclear core keeps re-igniting it.

    The very idea that Russia had a bunch of those dinosaurs in operation is a disgrace and an outrage. And yet for any problem that develops, they immediately drag out Chernobyl. That is ignorant, hysterical and irresponsible.

  3. What are your thoughts regarding the proposed expansion of Nuclear Power in the US? Or it’s current use for that matter? Obama has stated he still wants to move forward in spite of Japan.

    • I think it can be done safely enough. But I think the plants have to be built as a national, not regional resource. Allowing them to be built in less risky places.

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