Posted on 03/14/2011 8:08:53 AM PDT by EBH
The second hydrogen explosion in three days rocked a Japanese nuclear plant Monday, devastating the structure housing one reactor and injuring 11 workers. Water levels dropped precipitously at another reactor, completely exposing the fuel rods and raising the threat of a meltdown.
The morning explosion in Unit 3 of the Fukushima Dai-ichi plant was felt 25 miles (40 kilometers) away, but the plant's operator said radiation levels at the reactor remained within legal limits. Hours later, officials reported that fuel rods at Unit 2 were fully exposed at some point and may have been damaged.
Authorities have been pouring sea water into three reactors at the plant after cooling system failures in the wake of Friday's massive earthquake and tsunami, which is estimated to have killed at least 10,000 people. The latest explosion triggered an order for hundreds of people to stay indoors, said Chief Cabinet Secretary Yukio Edano.
(Excerpt) Read more at finance.yahoo.com ...
IEAE is stating that they ran out of seawater yesterday and that has been rectified now.
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
“Sea water injections into Units 1 and 3 were interrupted yesterday due to a low level in a sea water supply reservoir, but sea water injections have now been restored at both units.”
This suggests to me they have no circulation and the water is just steaming away....hence the explosions. Given this the decay heat is still a very large issue and not under control.
AGain....with the understanding that this is a local event and not a worldwide catastrophe.
Is this the reactor with plutonium in the rods?
It is no different than in the US. Natural Gas is not stored on site but connected via underground pipelines.
We use large storage facilities, either underground salt domes or depleted natural gas fields to store it underground and release it during the summer peak loads.
Keep in mind the transmission pipelines are typically compressed around 1,000 psi.
Would this system - the recombiners - have backups?
Last summer I visited the Grand Coulee Dam. I asked how big an earthquake the place could withstand. 8.9 was the answer.
I remember thinking that was in the realm of possibilities here in Washington State.
If that Dam broke, there’d be the entire backing of Lake Roosevelt racing to th pacific ocean, via the columbia river. A whole lot of towns along the river...
So, my point is that Earthquakes are bad whether it is nuke, or hydro.
Just talked with a local nuke expert here in Illinois who writes scenarios a lot like this for drills. We have two plants in Illinois that are basically identical to the Fukushima BWRs, Dresden and Quad Cities. He’s telling me (and I’m simplifying it to my own level of understanding, so you John Wayne operators lurking out there, cut me some slack) that H2 explosion are usually prevented inside the primary containment vessel by inerting the reaction via nitrogen.
The venting from the drywell to the interior of the containment building puts the hydrogen into a much larger volume of air, which does not have the nitrogen to neutralize the reaction, but which is unlikely to explode unless there is substantial build-up. Therefore, if there was an explosion, and there was, whatever was in primary containment that traveled with hydrogen has made it out to the environment.
However, he couldn’t tell from the information available what radioisotopes were released or in what quantity. But he said this is strictly a ground-based release, unlike Chernobyl, and contamination was definitely a local problem, and had no serious prospect of traveling very far from the plant, let alone overseas.
The purported discovery of trace readings 60 miles away was, in his mind, suspect, and he wanted to know whether that farther location was supported by the wind model. Furthermore, as he pointed out, the particulates disburse in such a way that even at distances relatively close to the plant, a formal cleanup may not be necessary, as the individual radioactive “cinders” will settle and isolate to such low concentrations they will not produce anything above normal background radiation levels we live with every day.
He also said we got far more hot fallout, in Arkansas, of all places, from Chinese -above-ground nuclear testing than we ever got from TMI or Chernobyl.
He does believe, however, that this will have a significant impact on the industry in terms of added regulatory burden for BWRs, a watershed change on the order of a TMI event, for example, which pushed us into doing serious simulation for the first time. Speculators take note.
It means all your hair is starting to fall out and have you checked those bleeding gums yet? Next you’re going to turn red and swell up like a giant frankfurter till you bust open and all your innards pop out!!
No more happy time for you!
Of course this might not happen too...potentially speaking..
I've had similar thoughts today...
Couldn't they just open a window?
One good thing I noted was that the steel superstructure of the first building to explode was still there. That makes the outer containment building more like a "blow-off" valve, and at least gives a limitation (although a high one) to the force of the explosion.
Markets tend to over-react first on bad news.
Judging from the old G-E diagrams that have been shown on the internet as this situation has unfolded, it looks like the reactor vessel for the BWR at Fukushima Daiichi is on the order of three meters in diameter. If we assume that the core is roughly cubical and fits inside this cylinder (I suspect it's closer to hexagonal) that means it's volume is more like 10 cubic meters, or 340 cubic feet, of uranium oxide, zirconium, stainless steel, and other very refractory materials. Just on the basis of crude volume, the Fukoshima core is on the order of only 1.3% the volume of the Chernobyl "core." If you can call it that.
I don't know if you've ever seen it, but there's a documentary that can be viewed on-line, about some physicists who have been living at Chernobyl and tunnelling into it for years. They actually succeeded in getting a camera into the core vessel. You can see the images if you watch the video. The short version is this: it's empty. The entire volume of the core, the stack, everything, burned off or was blown out by the explosion(s). The heaviest material (that didn't exit the building) melted down into the bottom to form the famous "elephant's foot" formations, so radioactive that even remote cameras sent to photograph them can't get good pictures because of radiation.
Chernobyl was the biggest dirty bomb in history; even the most determined terrorists, working undetected for years, couldn't concoct such a massive contamination source as that.
Compared to Chernobyl, the worst-case scenario at Fukushima isn't even in the ball park.
The decay heat will be an issue for quite some time. Folks don't realize how hot those rods really are. I believe in an earlier post I made mention these guys need more support. This isn't like putting a hot pan in water and a few minutes later it is cool to the touch. Although, that doesn't mean it is not under control either. This is going to take weeks to work through.
How long does it take to cool down a reactor? There are design specific variables there. The easiest way to answer that question is that NRC regulatory requirements for emergency power supplies is that they be available on the order of a month. You can render a plant in an acceptable condition within a few hours. However, heat is still being generated. If you had to stop, at any point, carrying away that heat, it would start building up again. Emergency cooling systems have to be available for weeks.
One would need to weigh the risk values before making a determination. Up until a few years ago, how often did we really hear about catastrophic tsunamis? I read about them in a book up until a few years ago. So, given that risk consideration some 40 years ago when the plants were built by the shoreline...thinking could very well have been close to a water source in the event of a catastrophe.
I don't know. Maybe someone can clarify...
You're right. Monday-morning quarterbacking is so easy and cheap.
Those tsunami videos are going to change a lot of thinking around the world I would imagine.
From the East Coast US, Japan is 13 Hours ahead of me - makes it just after 04:00 AM Tuesday Morning. If you’re in Cook County, IL., Japan is 14 Hours ahead; Pacific folks are 16 Hours ahead.
Reason being these were built years ago and there was no transportation system on the west coast to handle the equipment to built or maintain this size plant.
The steam that is vented probably contains radioactive material, but from what I have read, it is N-16 (radioactive nitrogen) which has a half-life of seconds. Once released, “radioactive material” is put into the atmosphere, but only for seconds. Converts to nitrogen.
Here is a good site that will help further explain what is happening. They have a complete detail of what is happening.
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