Fukushima: What Happened and What Needs To Be Done 370
IndigoDarkwolf writes "The sometimes confused media coverage around the Fukushima Daiichi nuclear plant left me wanting for a good summary. Apparently the BBC felt the same way, and now delivers an overview starting from the earthquake and concluding with the current state of the troubled reactors."
Japan to raise severity level of Fukushima acciden (Score:5, Interesting)
The Japan Times [japantimes.co.jp] reports:
The Nuclear Safety Commission of Japan released a preliminary calculation Monday saying that the crippled Fukushima Daiichi nuclear plant had been releasing up to 10,000 terabecquerels of radioactive materials per hour at some point after a massive quake and tsunami hit northeastern Japan on March 11.
The disclosure prompted the government to consider raising the accident's severity level to 7, the worst on an international scale, from the current 5, government sources said. The level 7 on the International Nuclear Event Scale has only been applied to the 1986 Chernobyl catastrophe.
If the levels they are reporting are correct then every hour (for a few hours) Fukushima was releasing roughly 0.1% of the total release from Chernobyl. If those levels were maintained for a day (which they were not), that would be almost 2% of Chernobyl per day.
Re:The truth (Score:4, Interesting)
Everything depended on the assumption that the coolant had a backup system.Once that assumption was mooted by the tsunami, the flaws in the rest of the system became known.
Not really. The real assumption that failed was that even if there was a complete loss of power in the plant, power could be reasonably quickly (8 hours) provided from outside the plant. The problems escalated because no supplies were available due to tsunami devastation, not even freshwater. The power grid was so damaged that an extra cable had to be laid to get any external power.
One of which is that once you lose cooling and can't get it restarted, you will inexorably have to vent hydrogen into a closed space full of air. Another is that there is no way to vent it to the outside to reduce the effects of an explosion.
The hydrogen was vented inside the containment on purpose, to allow activation products to decay. It could be vented outside the containment, but this would increase the radiation emissions, which the operators desperately wanted to minimize at that point. Hydrogen explosion was deemed an acceptable risk. It looks like this kind of mindset, "reduce public radiation exposure at all cost", is what caused the situation to escalate.
Another is that if the cooling system is completely bunged, there's no way to throw external coolant on the thing that has any effect.
The design assumption was that once cooling completely fails, the reactor will be drained, sealed and allowed to melt down. But this would necessitate a very costly cleanup which TEPCO wanted to avoid.
And another is that they stored the "spent" fuel rods in bunches in what is basically an open swimming pool, so that any chance it gets to evaporate the water around it will result in a fire.
Storing them elsewhere would necessarily expose the workers to more radiation. The point of the temporary storage near the reactor is to allow the fuel to lose most of its radioactivity before it is moved to a longer-term storage location.
What's criminal here is that these things were known to be bad assumptions long ago, but these reactors were operating as originally installed.
Each of the design considerations had a lot of thought behind it. The real problem is that the nuclear safety regulations are not based on a realistic risk analysis, but on fantasies (e.g. child drinking maximally contaminated water for an entire year, or somebody eating exclusively spinach for an entire year). As a result, the operators focused minimizing public radiation exposure rather than on stabilizing the facility, which was actually counterproductive.
Priorites, please!!! (Score:2, Interesting)
Reality will continue to disagree.
Let me FTFY: fearmongers will continue to disagree.
Apart from the usual "OMG, it's nuclear!!!" there are no valid arguments against nuclear power.
Let's have a reality check: it was the worst earthquake that ever hit Japan, the estimated material damage is $300 billion, the death count at this point is 12000 plus 13000 other people unaccounted for, presumably their bodies are either buried under the rubble or were washed to the sea.
All this, and all you hear about in the press is about four power plants???!!!??
Re:The truth (Score:4, Interesting)
There are a couple of issues I have seen in the reporting and comparing the report to the photos.
First is regarding the build up of Hydrogen. Some hydrogen build up over time is what has been portrayed. The actual is Zirconium is flammable the same as Magnesium and Titanium. All burn in water or steam. If you have ever seen a magnesium engine block hit with a fireman's hose, you get the idea. Powdered Zirconium is considered an explosive. Fine Zirconium wool as used in flashbulbs, but in an oxygen atmosphere. The reaction with water or steam starts at lower temperatures. The reaction is exothermic. The fuel itself adds heat. At temperatures near 800-1,000 C the reaction changes to a fire. This rapid oxidization of the Zirconium is the source of the rapid and LARGE release of Hydrogen. In the presence of burning Zirconium, there is no free Oxygen so in the presence of this ignition source there is no ignition of the Hydrogen in the Hydrogen/steam cloud. After the Zirconium burnt, the air in the room was then able to come in contact with glowing fuel pellets. This resulted in the ignition of the hydrogen.
From a few days ago, there was a report of some fuel rods found up to a mile away and was bulldozed under to shield them. They don't say much about the containment in #3 other than to say it may have been breeched. That is an understatement. Look up and spend a good amount of time watching videos of demolitions of buildings. Note the blast and resulting dust. The flash happens first then the building breaks. Explosions in #1 and #4 are consistent with the shell and a hydrogen explosion inside. The flash is over before the building ruptures. The ejected material is limited in distance and the blast shape is relatively uniform.
Watch the video of #3. There are some striking differences from anything already seen. First as the building ruptures, there is a large flash, much of it is OUTSIDE the building. Ignition may have been triggered by the blast and was due to the blast. Second using Newton's laws, look at the stuff ejected in the blast. This blast is far from uniform from a blast in the top of the building. At the end of the video, note the very large amount of heavy objects falling from the top of the blast dome. Unlike the other blasts, there are large holes from large heavy objects falling on the turbine hall. These are not from the roof of the building. The blasts from #1 and #4 do not have large heavy itmes falling out of it.
Examination of the high resolution UAV photos raises some more concerns. The containment may have been breeched, but most reporters are citing a lack of evidence of this. I'll tell you where to look. Look on the two pipes that run along the turbine buildings. Look between the turbine hall for #4 and the #4 reactor. Remember those pipes are about 10-12 feet in diameter each. Look for onsite vehicles for size references. Note the object sitting on both pipes. It is covered with dust from the #4 unit explosion. Zoom in and take a good look at it. Knowing the width of each of the pipes and the fact it is resting on both of them, guess it's width. Now look at he edge of the item. Care to guess how thick it is? Now note that it has a painted surface. Under the dust layer it is clearly Yellow. Care to guess what it is and where it came from?
While looking at the high resolution photos from the UAW, look next to the reactor 3 building where the pile of plumbing is lying next to the building. All that plumbing is uniform is size. I'm thinking that is scattered fuel rods from the cooling pond. I think the cooling pond is gone and the steam rising form #3 is not from the pond, but form the containment known as the dry well. I can not tell from the photo if the reactor lid is in place. I'm guessing either a hydrogen buildup in the dry-well exploded or the lid to the reactor blew off. This resulted in the outer containment breech shown in the video. This breech then released the contained Hydrogen which then ignited, This is seen as the flash outside the building.
Persective indeed (Score:5, Interesting)
The waste is the biggest problem?
1. No civilian spent fuel was ever accidentally or on purpose released into the environment, even though transportation of it is common. Soviet military waste was sometimes dumped directly into rivers, but this is really unrelated to nuclear power.
2. The only person that ever died from civilian spent fuel was a guy that got ran over by a train during an anti-nuclear protest. http://en.wikipedia.org/wiki/Death_of_S%C3%A9bastien_Briat [wikipedia.org]
3. If someone used only nuclear electricity (average U.S. electricity consumption) from present reactor technology for their entire life, he would generate about a soda can of waste.
4. Vitrified nuclear waste is completely insoluble in water. It's rather hard to spread it over a large area. Even if it was just dumped into the ocean, there would be no harm to humans - the waste would bury itself in the seabed. We are not using this solution because Greenpeace and other assorted clowns do not understand anything about marine biology or oceanography. http://www.theatlantic.com/past/docs/issues/96oct/seabed/seabed.htm [theatlantic.com]
5. Even if the waste does somehow escape into the environment, it is very easy to detect this. Radiation detectors are very cheap and compact compared to the laboratory setups needed to analyze chemical pollution - so cheap and compact that every radiation worker has their own detector that keeps track of their exposure. This fact facilitates cleanup operations.
I can understand the uneasy feelings, but let's have some perspective. This isn't even as bad as the hazardous chemical waste we already have to deal with (e.g. from semiconductor production, mining and metallurgy), which unlike nuclear waste will remain toxic forever.
Re:The truth (Score:5, Interesting)
I agree with most of your first three paragraphs, but the second two dealing with the UAV photos I have to rebut.
Note the object sitting on both pipes. ... guess it's width. Now look at he edge of the item. Care to guess how thick it is? ... Under the dust layer it is clearly Yellow. Care to guess what it is and where it came from?
You're implying that it's part of the containment vessel. Let's look at a specific picture for comparison: http://cryptome.org/eyeball/daiichi-npp/pict10.jpg [cryptome.org]
My origin is at the upper left. The object you're describing is at X:20%, Y60%. Note the thickness of the cut off pipe at X:70%, Y:30%. This is thin walled stuff. In other photos you can see the twin pipes are at the same level as that raised section, and similarly supported. The containment vessel is very thick and heavy. If that was the dome or another section of the containment flung from #3, it would have destroyed or at least damaged the pipe. My analysis: It's just a chunk of wall, similar to the chunks laying in front of #4.
... look next to the reactor 3 building where the pile of plumbing is lying next to the building. All that plumbing is uniform is size. I'm thinking that is scattered fuel rods from the cooling pond.
http://cryptome.org/eyeball/daiichi-npp/pict6.jpg [cryptome.org] - Are you referring to the stuff to the lower-left of the steam, and similar-sized stuff strewn across the top of the turbine hall? I think it's too big to be fuel rods, and too small and mangled to be fuel assemblies. It looks like structural steel from the building.
Lastly, if the stuff flung up in the explosion was fuel rods or containment chunks, we'd be seeing much higher radiation levels in the vicinity of the #3 building. Instead the high levels are centered around #2, where there *was* an explosion inside containment that caused a breach.