Nuclear explosion in Japan

[shaunbhoy]

I just wonder what the fallout from all this is going to be??

[Ardesco]

Almost as much rubbish in this thread as in the mainstream media...

A few snippets from Why I am not worried about Japan’s nuclear reactors. | Morgsatlarge – blogorific.

The nuclear fuel is uranium oxide. Uranium oxide is a ceramic with a very high melting point of about 3000 °C. The fuel is manufactured in pellets (think little cylinders the size of Lego bricks). Those pieces are then put into a long tube made of Zircaloy with a melting point of 2200 °C, and sealed tight. The assembly is called a fuel rod. These fuel rods are then put together to form larger packages, and a number of these packages are then put into the reactor. All these packages together are referred to as “the core”.

The Zircaloy casing is the first containment. It separates the radioactive fuel from the rest of the world.

The core is then placed in the “pressure vessels”. That is the pressure cooker we talked about before. The pressure vessels is the second containment. This is one sturdy piece of a pot, designed to safely contain the core for temperatures several hundred °C. That covers the scenarios where cooling can be restored at some point.

The entire “hardware” of the nuclear reactor – the pressure vessel and all pipes, pumps, coolant (water) reserves, are then encased in the third containment. The third containment is a hermetically (air tight) sealed, very thick bubble of the strongest steel and concrete. The third containment is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. For that purpose, a large and thick concrete basin is cast under the pressure vessel (the second containment), all inside the third containment. This is the so-called “core catcher”. If the core melts and the pressure vessel bursts (and eventually melts), it will catch the molten fuel and everything else. It is typically built in such a way that the nuclear fuel will be spread out, so it can cool down.

This third containment is then surrounded by the reactor building. The reactor building is an outer shell that is supposed to keep the weather out, but nothing in. (this is the part that was damaged in the explosion, but more to that later).

the first “type” of radioactive material is the uranium in the fuel rods, plus the intermediate radioactive elements that the uranium splits into, also inside the fuel rod (Cesium and Iodine).

There is a second type of radioactive material created, outside the fuel rods. The big main difference up front: Those radioactive materials have a very short half-life, that means that they decay very fast and split into non-radioactive materials. By fast I mean seconds. So if these radioactive materials are released into the environment, yes, radioactivity was released, but no, it is not dangerous, at all. Why? By the time you spelled “R-A-D-I-O-N-U-C-L-I-D-E”, they will be harmless, because they will have split up into non radioactive elements. Those radioactive elements are N-16, the radioactive isotope (or version) of nitrogen (air). The others are noble gases such as Argon. But where do they come from? When the uranium splits, it generates a neutron (see above). Most of these neutrons will hit other uranium atoms and keep the nuclear chain reaction going. But some will leave the fuel rod and hit the water molecules, or the air that is in the water. Then, a non-radioactive element can “capture” the neutron. It becomes radioactive. As described above, it will quickly (seconds) get rid again of the neutron to return to its former beautiful self.

This second “type” of radiation is very important when we talk about the radioactivity being released into the environment later on.

The plant came close to a core meltdown. Here is the worst-case scenario that was avoided: If the seawater could not have been used for treatment, the operators would have continued to vent the water steam to avoid pressure buildup. The third containment would then have been completely sealed to allow the core meltdown to happen without releasing radioactive material. After the meltdown, there would have been a waiting period for the intermediate radioactive materials to decay inside the reactor, and all radioactive particles to settle on a surface inside the containment. The cooling system would have been restored eventually, and the molten core cooled to a manageable temperature. The containment would have been cleaned up on the inside. Then a messy job of removing the molten core from the containment would have begun, packing the (now solid again) fuel bit by bit into transportation containers to be shipped to processing plants. Depending on the damage, the block of the plant would then either be repaired or dismantled.

[stek]

My Nuclear Physicist buddy told me this. On Facebook!...

"A testament to the 40 year old design and safety of the reactors to withstand such an extreme seismic event and a subsequent Tsunami which took out the coolant systems and still provide containment of the fuel. Hydrogen explosions looked dramatic but appear not to be of sufficient magnitude to breach the containment. What worries me more is seeing video of people wearing paper masks as if they offer some kind of protection, and full plastic suited individuals checking members of the public in civilian clothes for contam 40km from the site."

[TimberWolf]

My Nuclear Physicist buddy told me this. On Facebook!...

"A testament to the 40 year old design and safety of the reactors to withstand such an extreme seismic event and a subsequent Tsunami which took out the coolant systems and still provide containment of the fuel. Hydrogen explosions looked dramatic but appear not to be of sufficient magnitude to breach the containment. What worries me more is seeing video of people wearing paper masks as if they offer some kind of protection, and full plastic suited individuals checking members of the public in civilian clothes for contam 40km from the site."

Those lullaby stories (originating from the nuclear industry I guess) that might have been worth the time of day yesterday are starting to look silly now. Things are obviously not going well and the Japanese government are asking for international help.

Industry executives in touch with their counterparts in Japan Monday night grew increasingly alarmed about the risks posed by the No. 2 reactor.

“They’re basically in a full-scale panic” among Japanese power industry managers, said a senior nuclear industry executive. The executive is not involved in managing the response to the reactors’ difficulties but has many contacts in Japan. “They’re in total disarray, they don’t know what to do.”
http://www.nytimes.com/2011/03/15/wo...agewanted=1&hp

Let's hope the wind direction is not towards a major city if it does blow. It won't be a nuclear blast of course, just a dirty release.

[Ruprect]

My Nuclear Physicist buddy told me this. On Facebook!...

"A testament to the 40 year old design and safety of the reactors to withstand such an extreme seismic event and a subsequent Tsunami which took out the coolant systems and still provide containment of the fuel. Hydrogen explosions looked dramatic but appear not to be of sufficient magnitude to breach the containment. What worries me more is seeing video of people wearing paper masks as if they offer some kind of protection, and full plastic suited individuals checking members of the public in civilian clothes for contam 40km from the site."

Duck and cover!

[AtW]

I am becoming seriously anti-nuclear now (apart from military nukes).

[AlfredJPruffock]

Those lullaby stories (originating from the nuclear industry I guess) that might have been worth the time of day yesterday are starting to look silly now. Things are obviously not going well and the Japanese government are asking for international help.



Let's hope the wind direction is not towards a major city if it does blow. It won't be a nuclear blast of course, just a dirty release.

IF reactor Three does go into full meltdown mode - bearing in mind the enriched Plutonium that they have been using in that reactor Three since last August - then makes its way into the atmosphere - it will by a grave challenge not only for Japan but the World.

[TimberWolf]

Gamma Radiation In Fukushima-Downwind Ibaraki Disclosed, 30 Times Above Normal | zero hedge

(not something to run around like a headless chicken about, but worth watching)

I'd been looking at that page over the day or so too. They removed survey sites around Fukushima (saying "under survey") and now the site doesn't work at all.

[AlfredJPruffock]

OK for those who doe't know about MOX (Reactor Three)


What is MOX fuel?

Fuel consisting of a mixture of uranium and plutonium oxides is referred to as a MOX (mixed oxide) fuel. Uranium fuel consists of enriched uranium in which the concentration of uranium 235 -- the combustible element in natural uranium -- is artificially increased. In MOX fuel, by contrast, anything from 4 to 9 percent plutonium is used in place of enriched uranium to mix with natural uranium or with the uranium that is left after enrichment (i.e., depleted uranium).

Japan's MOX Program

Part of Japan's nuclear policy is to implement the MOX utilization program; that is, to irradiate MOX fuel in conventional light water reactors (LWRs). Because of the fact that discussions are still under way with the local governments and citizens, the commercial use of MOX fuel has yet to begin. Nevertheless, as mentioned at the outset, Japan, scarce in energy resources, is continuing its policy of establishing a nuclear fuel cycle. MOX utilization, therefore, remains a crucial part of completing the fuel cycle. The Japanese electricity industry intends to continue its efforts to garner support and understanding from related parties in order to carry out the MOX utilization program in accordance with this policy

[TimberWolf]

Breaking news Newsnight "Big explosion" at reactor #2