patrick.net

And now bad news:

New fire hits Japan nuclear plant

http://www.bbc.co.uk/news/world-asia-pacific-12754883

#4 reactor is on fire again.

The situation with #4 is not clear now. Smoke was noted at 5:45AM but NHK said it was gone later.

Still no clear info on this.

terriDeaner says

Do you understand that if you ingest trace amounts of radioactive cesium or strontium it will accumulate over time in your body, replacing normal elements like potassium and calcium? Imagine the blood cancer risk resultant from having a radioactive skeleton. And the problem is compounded by bioaccumulation through the food chain. This means that low levels of radioactive dust over grass gets concentrated by cows eating the grass, and further concentrated in humans eating the cows.

Trace amounts of cs will not accumulate in your body. It passes out through the urine and feces. You ingest and pass out non radioactive cs all the time. It's naturally occurring and is all around us. Radioactive cs does exactly the same thing. Much larger amounts than trace are needed to accumulate. It's just not possible for those levels of concentrations of cs to drift 6000 miles short of a nuclear war.

You keep comparing Chernobyl with the Japanese plants. Chernobyl didn't have a containment building. The explosan simply tossed the roof of the reactor. Over 200 tons of material thrown high into the air. Most of it landed on the nearby scandenavian countries where is was absorbed by the environment and passed up the food chain to some degree. There is a world of difference between several hundred miles and over 6000 miles.

None of this matters since you keep coming back to the same tired argument that all radiation is the same and any trace amount is harmful. Pure hokum.

bob2356 says

Chernobyl didn’t have a containment building.

Maybe you haven't been keeping up with current events, but neither do 2 out of the 3 Fukushima 1 scrammed reactors.

One other problem is that there are thousands of nuclear rods sitting in cooling pools at the upper levels of all 6 power plants.

One reactor is currently emitting steam or white smoke at this time. If this is reactor 2 this is steam directly from the core, which has been 30% damaged due to loosing all coolant for several hours.

Turns out the "smoking" reactor is Unit 3.

The one fueled with 5% plutonium.

Not good.

Live update from TEPCO now.

Workers have suspended operations in the facility, waiting for the somewhat elevated radiation levels to abate (~6 millisieverts at the main gate, probably much higher at the control facility).

TEPCO says maybe no water in #4 spent fuel pool.

Cores could have melted in the empty cooling pool.

Could be a likely scenario.

TEPCO wants to inject water as quickly as possible.

No shield in #4 fuel left. Workers cannot approach.

From bbc asia-pacific:

0320: Staff have now been evacuated from Fukushima because of a spike in radiation levels, Chief Cabinet Secretary Yukio Edano told a news conference.

What is going on?

Things are going out of control. Now being interrupted by emergency earthquake warning for Ibaraki.

I'm not really up on this sort of thing, but Japan being the land of robots and all.... don't they have views of what's going on inside? I mean I would think they could deploy widgets with cameras on them all over the place. Radiation/heat issues?

I am also curious why more automated devices were not deployed.

Status update 6 out.

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1300245068P.pdf

Main page here to follow it yourself:

http://www.jaif.or.jp/english/

No info on fuel rod integrity in the cooling pools for #1-3...

Here's a wind speed/direction map for Japan via zerohedge... can anyone read Japanese? AiJ?

http://www.weather-report.jp/com/home/kishomap/fusoku/japan_l.html

Better news from bbc:

0623: Workers at the Fukushima plant have returned after being evacuated, CNN is quoting Tokyo Electric Power Company as saying.

From 10:20AM JST millisievert levels were registered at the main gate, briefly peaking at 10.8mSv at 12:30.

Could be much higher at the reactors.

Picture of Unit 4 is quite shocking:

#3 is on the left and was the one with the big explosion on Monday.

This has been contained just about as well as subprime was in 2008.

Further evidence that this is an ongoing crisis. Nothing is certain.

And the rest of the pictures from that nytimes series were fucking depressing. How awful.

LOL. TEPCO press conference is a riot right now. The reporters there are assholes.

TEPCO had a live press conference and 10 minutes in the reporters could see on NHK that CH-47s arrived with water baskets and the reporters started going WTF and the TEPCO big cheeses were kinda laughing a little, or amused that the water operation was starting before TEPCO could tell the reporters.

TEPCO said:

smoke coming out of spent fuel pool temperature water boiled off of #2.

180 workers back removing debris from the exploded plants. (Fun job.)

Dick reporter assaulting the nice TEPCO senior manager about drywell and suppression pool pressure is "downscale" which I think means it has lost pressurization too. This means when #3 core vents excess pressure it will also vent into the plant directly

Frankly I don't see how anybody can be working in this environment, with all these rods being exposed to the air.

Now they're ganging up on TEPCO guys.

1,2,3 reactors are cooling with seawater and venting radioactive steam.

Emperor is now talking to people, saying the usual stuff.

Watching TBS now . . .

They're showing how they moved the fuel rods from inside the #4's reactor to the spent fuel pool.

The reporters are talking about how dangerous this is, now that there's no coolant left in the pool!

So much for "containment".

I read somewhere that with a naked core exposed to air it's basically Chernobyl-level dosage to anyone coming close to Unit 4 . . . which is why they are employing helicopters now to try to get the core under water again.

To out things in perspective:
Chernobyl release way more radiation than either Hiroshima or Nagasaki, and it didn't affect us, even though it's closer to the US (at least where I am at).

Also, from what I've read, one of changes you are going to see from this is they way backup generators at nuclear plants are placed. Power plants are also major consumers of electricity, and in the case of a nuclear plant, having those backup (most likely diesel) generators to keep things like pump running is absolutely necessary. The problem here is that they placed them in the basement which the tsunami flooded! As in:

Didn't the same thing happen with Katrina where the pumps were underwater or something like that?

Troy says

Frankly I don’t see how anybody can be working in this environment, with all these rods being exposed to the air.

Wearing a radiation suit aling with individual radiation monitors and limiting exposure. you use a fair number of people who only work there for limited amounts of time. Also, if possible use robots if you can get them. They might have one of those handy in a place like Japan or a nuclear power plant.

Obligatory radiation suit picture:

Vicente says

I’m not really up on this sort of thing, but Japan being the land of robots and all…. don’t they have views of what’s going on inside? I mean I would think they could deploy widgets with cameras on them all over the place. Radiation/heat issues?

If I had to guess, the robots that they have might not be in the right place and most likely not designed for this particular task. In so far as radiation/heat issues those can be accounted for in the design of the robot. These things have sensors all over the place that work just fine because they are designed to work there.

More importantly, anyone see any obvious short term investment opportunities?

Level 6 now...

Possibly level 7.

http://en.wikipedia.org/wiki/International_Nuclear_Event_Scale

More learned here from the foreign media than from the Japanese media.

Today wind was blowing east toward the Pacific Ocean.

Saw the news today, apparently people are stocking up on PotassiumIodide (US West Coast).

zzyzzx says

I agree. The stuff I see written by people is so stupid and illogical that it isn’t funny. At least I used to work at a nuclear plant, and don’t expect this situation to amount to much, as long as the can pump in seawater until they get the regular systems working, they’ll be fine.

You don’t see Cherynobyl style nuclear reactors in palce like the US or Japan.

In all seriousness, do you really feel the same way today? Yes, the US and Japan do not use Chernobyl style reactors, so an exact repeat of a "Chernobyl event" is not even possible. However, it seems that the containment vessels for Daiichi #2 and #3 have cracked, allowing ongoing releases of radioactive material. Weren't these reactors DESIGNED to avoid this exact problem???

I for one hope your prediction is at least partially correct and that these containment vessels do not break down any further. I fear that they may not be able to continue pumping seawater for cooling, however.

To top it off, it seems like the situation in Japan could get much WORSE than Chernobyl because of a huge design flaw in the way that spent fuel is stored at these boiling water reactors (same reactor design as the one you used to work at, yes?). Essentially each reactor has an UNREINFORCED reactor core full of spent fuel sitting on top of the containment vessels of #1-#6.

I found this graphic by tracking through a series of links from the website you provided for you former place of employment:
http://www.nrc.gov/reactors/generic-bwr.pdf

It is a generic schematic from the US nuclear regulatory commission, and it shows the spent-fuel cooling pool located at the top of the typical boiling water reactor used in the US. Was this how your plant was set up as well?

from bbc asia-pacific:

1759: The embassy says there are "numerous factors in the aftermath of the earthquake and Tsunami, including weather, wind direction and speed, and the nature of the reactor problem that affect the risk of radioactive contamination within this 50 mile (80 km) radius or the possibility of lower-level radioactive materials reaching greater distances."

1757: This is an extract is from the US embassy's advice to its citizens in Japan: "Consistent with the NRC [Nuclear Regulatory Commission] guidelines that apply to such a situation in the United States, we are recommending, as a precaution, that American citizens who live within 50 miles (80 kilometers) of the Fukushima Nuclear Power Plant evacuate the area or to take shelter indoors if safe evacuation is not practical."

But also consider this opinion

from bbc asia-pacific:

1818: The US Environmental Protection Agency says it is increasing its monitoring of radiation along the western coast and Pacific territories, AP reports. However the US Nuclear Regulatory Commission has said it does not expect harmful levels to reach North America.

and this statement from the EPA:

http://www.epa.gov/radiation/statement.html

And (finally!) how to access online monitoring in near-real time

http://www.epa.gov/narel/radnet/pdf/How_to_Access_RadNet_Data.pdf

Let's hope this works-

from bbc asia-pacific:

1832: The AP news agency is quoting Tepco as saying a new power line is almost ready which could end the crisis. The disruption of power to the pumps which send coolant through the reactors is what led to their overheating.

Finding recent facts on this with any depth from US media is useless. Thanks for pointing me to BBC Asia-Pacific.

Vicente says

Finding recent facts on this with any depth from US media is useless. Thanks for pointing me to BBC Asia-Pacific.

Sure, you're welcome. It seemed like the nytimes was on top of this story over the weekend, but has since lagged behind on their updates.

I have no idea where the used fuel was stored at Browns Ferry. I tried to stay away from that whole part of the plant anyway, and I'm guessing that my badge wouldn't have let me into that part of the plant either (never actually tried to get into that part of the plant). You have to understand that these places are huge, more like the size of a decent sized college campus with lots of people in it with a large lot of land around it, with the while place the size of a city.

What I always thought was interesting about the place was that it was famous for catching on fire, and always for a stupid reason that didn't affect the reactor itself. Once someone was testing some cable penetration seals (places where wires went through the wall) and they list up something that generated the smoke, which them caught the cabling on fire in a wiring area below a control room. Once a some wooden cooling towers burnt down (these were regular low rise cooling towers, not the parabolic ones you are thinking of). What was interesting is that the plant has a visitors center that tourists used to be able to go to and use an interactive display to virtually walk around the plant. In this interactive display you could walk right past and view the charred remains of this cooling tower. I'm guessing that there aren't any nuclear power plant visitors centers open to the public anymore. I wanted to visit the one at 3 Mile Island, but when I researched it I found that it was closed (this was after 9/11 and TMI is the closest one to me, I think).

And a dissenting opinion:

http://thechart.blogs.cnn.com/2011/03/16/experts-u-s-wont-feel-health-effects-from-japan/?hpt=T2

Found this comment under one of the articles...

http://sanfrancisco.cbslocal.com/2011/03/15/from-tokyo-to-calif-radiation-tracking-gets-crowdsourced/

Dennis Kimball

Fukushima Nuclear Accident – a simple and accurate explanation
Posted on 13 March 2011 by Barry Brook
Along with reliable sources such as the IAEA and WNN updates, there is an incredible amount of misinformation and hyperbole flying around the internet and media right now about the Fukushima nuclear reactor situation.
In the BNC post Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake (and in the many comments that attend the top post), a lot of technical detail is provided, as well as regular updates. But what about a layman’s summary? How do most people get a grasp on what is happening, why, and what the consequences will be?
Below I reproduce a summary on the situation prepared by Dr Josef Oehmen, a research scientist at MIT, in Boston. He is a PhD Scientist, whose father has extensive experience in Germany’s nuclear industry. This was first posted by Jason Morgan earlier this evening, and he has kindly allowed me to reproduce it here. I think it is very important that this information be widely understood.
Please also take the time to read this: An informed public is key to acceptance of nuclear energy — it was never more relevant than now.
———————————
I am writing this text (Mar 12) to give you some peace of mind regarding some of the troubles in Japan, that is the safety of Japan’s nuclear reactors. Up front, the situation is serious, but under control. And this text is long! But you will know more about nuclear power plants after reading it than all journalists on this planet put together.
There was and will *not* be any significant release of radioactivity.
By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.
I have been reading every news release on the incident since the earthquake. There has not been one single (!) report that was accurate and free of errors (and part of that problem is also a weakness in the Japanese crisis communication). By “not free of errors” I do not refer to tendentious anti-nuclear journalism – that is quite normal these days. By “not free of errors” I mean blatant errors regarding physics and natural law, as well as gross misinterpretation of facts, due to an obvious lack of fundamental and basic understanding of the way nuclear reactors are build and operated. I have read a 3 page report on CNN where every single paragraph contained an error.
We will have to cover some fundamentals, before we get into what is going on.
Construction of the Fukushima nuclear power plants
The plants at Fukushima are so called Boiling Water Reactors, or BWR for short. Boiling Water Reactors are similar to a pressure cooker. The nuclear fuel heats water, the water boils and creates steam, the steam then drives turbines that create the electricity, and the steam is then cooled and condensed back to water, and the water send back to be heated by the nuclear fuel. The pressure cooker operates at about 250 °C.
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. 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), which is filled with graphite, 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 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).
Fundamentals of nuclear reactions
The uranium fuel generates heat by nuclear fission. Big uranium atoms are split into smaller atoms. That generates heat plus neutrons (one of the particles that forms an atom). When the neutron hits another uranium atom, that splits, generating more neutrons and so on. That is called the nuclear chain reaction.
Now, just packing a lot of fuel rods next to each other would quickly lead to overheating and after about 45 minutes to a melting of the fuel rods. It is worth mentioning at this point that the nuclear fuel in a reactor can *never* cause a nuclear explosion the type of a nuclear bomb. Building a nuclear bomb is actually quite difficult (ask Iran). In Chernobyl, the explosion was caused by excessive pressure buildup, hydrogen explosion and rupture of all containments, propelling molten core material into the environment (a “dirty bomb”). Why that did not and will not happen in Japan, further below.
In order to control the nuclear chain reaction, the reactor operators use so-called “control rods”. The control rods absorb the neutrons and kill the chain reaction instantaneously. A nuclear reactor is built in such a way, that when operating normally, you take out all the control rods. The coolant water then takes away the heat (and converts it into steam and electricity) at the same rate as the core produces it. And you have a lot of leeway around the standard operating point of 250°C.
The challenge is that after inserting the rods and stopping the chain reaction, the core still keeps producing heat. The uranium “stopped” the chain reaction. But a number of intermediate radioactive elements are created by the uranium during its fission process, most notably Cesium and Iodine isotopes, i.e. radioactive versions of these elements that will eventually split up into smaller atoms and not be radioactive anymore. Those elements keep decaying and producing heat. Because they are not regenerated any longer from the uranium (the uranium stopped decaying after the control rods were put in), they get less and less, and so the core cools down over a matter of days, until those intermediate radioactive elements are used up.
This residual heat is causing the headaches right now.
So 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 Xenon. 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.

What happened at Fukushima

I will try to summarize the main facts. The earthquake that hit Japan was 7 times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; the difference between the 8.2 that the plants were built for and the 8.9 that happened is 7 times, not 0.7). So the first hooray for Japanese engineering, everything held up.
When the earthquake hit with 8.9, the nuclear reactors all went into automatic shutdown. Within seconds after the earthquake started, the control rods had been inserted into the core and nuclear chain reaction of the uranium stopped. Now, the cooling system has to carry away the residual heat. The residual heat load is about 3% of the heat load under normal operating conditions.
The earthquake destroyed the external power supply of the nuclear reactor. That is one of the most serious accidents for a nuclear power plant, and accordingly, a “plant black out” receives a lot of attention when designing backup systems. The power is needed to keep the coolant pumps working. Since the power plant had been shut down, it cannot produce any electricity by itself any more.
Things were going well for an hour. One set of multiple sets of emergency Diesel power generators kicked in and provided the electricity that was needed. Then the Tsunami came, much bigger than people had expected when building the power plant (see above, factor 7). The tsunami took out all multiple sets of backup Diesel generators.
When designing a nuclear power plant, engineers follow a philosophy called “Defense of Depth”. That means that you first build everything to withstand the worst catastrophe you can imagine, and then design the plant in such a way that it can still handle one system failure (that you thought could never happen) after the other. A tsunami taking out all backup power in one swift strike is such a scenario. The last line of defense is putting everything into the third containment (see above), that will keep everything, whatever the mess, control rods in our out, core molten or not, inside the reactor.
When the diesel generators were gone, the reactor operators switched to emergency battery power. The batteries were designed as one of the backups to the backups, to provide power for cooling the core for 8 hours. And they did.
Within the 8 hours, another power source had to be found and connected to the power plant. The power grid was down due to the earthquake. The diesel generators were destroyed by the tsunami. So mobile diesel generators were trucked in.
This is where things started to go seriously wrong. The external power generators could not be connected to the power plant (the plugs did not fit). So after the batteries ran out, the residual heat could not be carried away any more.
At this point the plant operators begin to follow emergency procedures that are in place for a “loss of cooling event”. It is again a step along the “Depth of Defense” lines. The power to the cooling systems should never have failed completely, but it did, so they “retreat” to the next line of defense. All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator, right through to managing a core meltdown.
It was at this stage that people started to talk about core meltdown. Because at the end of the day, if cooling cannot be restored, the core will eventually melt (after hours or days), and the last line of defense, the core catcher and third containment, would come into play.
But the goal at this stage was to manage the core while it was heating up, and ensure that the first containment (the Zircaloy tubes that contains the nuclear fuel), as well as the second containment (our pressure cooker) remain intact and operational for as long as possible, to give the engineers time to fix the cooling systems.
Because cooling the core is such a big deal, the reactor has a number of cooling systems, each in multiple versions (the reactor water cleanup system, the decay heat removal, the reactor core isolating cooling, the standby liquid cooling system, and the emergency core cooling system). Which one failed when or did not fail is not clear at this point in time.
So imagine our pressure cooker on the stove, heat on low, but on. The operators use whatever cooling system capacity they have to get rid of as much heat as possible, but the pressure starts building up. The priority now is to maintain integrity of the first containment (keep temperature of the fuel rods below 2200°C), as well as the second containment, the pressure cooker. In order to maintain integrity of the pressure cooker (the second containment), the pressure has to be released from time to time. Because the ability to do that in an emergency is so important, the reactor has 11 pressure release valves. The operators now started venting steam from time to time to control the pressure. The temperature at this stage was about 550°C.
This is when the reports about “radiation leakage” starting coming in. I believe I explained above why venting the steam is theoretically the same as releasing radiation into the environment, but why it was and is not dangerous. The radioactive nitrogen as well as the noble gases do not pose a threat to human health.

At some stage during this venting, the explosion occurred. The explosion took place outside of the third containment (our “last line of defense”), and the reactor building. Remember that the reactor building has no function in keeping the radioactivity contained. It is not entirely clear yet what has happened, but this is the likely scenario: The operators decided to vent the steam from the pressure vessel not directly into the environment, but into the space between the third containment and the reactor building (to give the radioactivity in the steam more time to subside). The problem is that at the high temperatures that the core had reached at this stage, water molecules can “disassociate” into oxygen and hydrogen – an explosive mixture. And it did explode, outside the third containment, damaging the reactor building around. It was that sort of explosion, but inside the pressure vessel (because it was badly designed and not managed properly by the operators) that lead to the explosion of Chernobyl. This was never a risk at Fukushima. The problem of hydrogen-oxygen formation is one of the biggies when you design a power plant (if you are not Soviet, that is), so the reactor is build and operated in a way it cannot happen inside the containment. It happened outside, which was not intended but a possible scenario and OK, because it did not pose a risk for the containment.
So the pressure was under control, as steam was vented. Now, if you keep boiling your pot, the problem is that the water level will keep falling and falling. The core is covered by several meters of water in order to allow for some time to pass (hours, days) before it gets exposed. Once the rods start to be exposed at the top, the exposed parts will reach the critical temperature of 2200 °C after about 45 minutes. This is when the first containment, the Zircaloy tube, would fail.
And this started to happen. The cooling could not be restored before there was some (very limited, but still) damage to the casing of some of the fuel. The nuclear material itself was still intact, but the surrounding Zircaloy shell had started melting. What happened now is that some of the byproducts of the uranium decay – radioactive Cesium and Iodine – started to mix with the steam. The big problem, uranium, was still under control, because the uranium oxide rods were good until 3000 °C. It is confirmed that a very small amount of Cesium and Iodine was measured in the steam that was released into the atmosphere.
It seems this was the “go signal” for a major plan B. The small amounts of Cesium that were measured told the operators that the first containment on one of the rods somewhere was about to give. The Plan A had been to restore one of the regular cooling systems to the core. Why that failed is unclear. One plausible explanation is that the tsunami also took away / polluted all the clean water needed for the regular cooling systems.
The water used in the cooling system is very clean, demineralized (like distilled) water. The reason to use pure water is the above mentioned activation by the neutrons from the Uranium: Pure water does not get activated much, so stays practically radioactive-free. Dirt or salt in the water will absorb the neutrons quicker, becoming more radioactive. This has no effect whatsoever on the core – it does not care what it is cooled by. But it makes life more difficult for the operators and mechanics when they have to deal with activated (i.e. slightly radioactive) water.
But Plan A had failed – cooling systems down or additional clean water unavailable – so Plan B came into effect. This is what it looks like happened:
In order to prevent a core meltdown, the operators started to use sea water to cool the core. I am not quite sure if they flooded our pressure cooker with it (the second containment), or if they flooded the third containment, immersing the pressure cooker. But that is not relevant for us.
The point is that the nuclear fuel has now been cooled down. Because the chain reaction has been stopped a long time ago, there is only very little residual heat being produced now. The large amount of cooling water that has been used is sufficient to take up that heat. Because it is a lot of water, the core does not produce sufficient heat any more to produce any significant pressure. Also, boric acid has been added to the seawater. Boric acid is “liquid control rod”. Whatever decay is still going on, the Boron will capture the neutrons and further speed up the cooling down of the core.
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.

Now, where does that leave us?

The plant is safe now and will stay safe.

Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.

Some radiation was released when the pressure vessel was vented. All radioactive isotopes from the activated steam have gone (decayed). A very small amount of Cesium was released, as well as Iodine. If you were sitting on top of the plants’ chimney when they were venting, you should probably give up smoking to return to your former life expectancy. The Cesium and Iodine isotopes were carried out to the sea and will never be seen again.

There was some limited damage to the first containment. That means that some amounts of radioactive Cesium and Iodine will also be released into the cooling water, but no Uranium or other nasty stuff (the Uranium oxide does not “dissolve” in the water). There are facilities for treating the cooling water inside the third containment. The radioactive Cesium and Iodine will be removed there and eventually stored as radioactive waste in terminal storage.

The seawater used as cooling water will be activated to some degree. Because the control rods are fully inserted, the Uranium chain reaction is not happening. That means the “main” nuclear reaction is not happening, thus not contributing to the activation. The intermediate radioactive materials (Cesium and Iodine) are also almost gone at this stage, because the Uranium decay was stopped a long time ago. This further reduces the activation. The bottom line is that there will be some low level of activation of the seawater, which will also be removed by the treatment facilities.

The seawater will then be replaced over time with the “normal” cooling water

The reactor core will then be dismantled and transported to a processing facility, just like during a regular fuel change.

Fuel rods and the entire plant will be checked for potential damage. This will take about 4-5 years.

The safety systems on all Japanese plants will be upgraded to withstand a 9.0 earthquake and tsunami (or worse)

I believe the most significant problem will be a prolonged power shortage. About half of Japan’s nuclear reactors will probably have to be inspected, reducing the nation’s power generating capacity by 15%. This will probably be covered by running gas power plants that are usually only used for peak loads to cover some of the base load as well. That will increase your electricity bill, as well as lead to potential power shortages during peak demand, in Japan.

Not the kind of opinion I'd be inclined to trust. Looks like that article is horribly out of date.

joshuatrio says

Posted on 13 March 2011 by Barry Brook

joshuatrio says

I am writing this text (Mar 12) to give you some peace of mind regarding some of the troubles in Japan, that is the safety of Japan’s nuclear reactors. Up front, the situation is serious, but under control.

And way off target with its predictions:

joshuatrio says

Now, where does that leave us?

The plant is safe now and will stay safe.

Japan is looking at an INES Level 4 Accident: Nuclear accident with local consequences. That is bad for the company that owns the plant, but not for anyone else.

joshuatrio says

There was and will *not* be any significant release of radioactivity.
By “significant” I mean a level of radiation of more than what you would receive on – say – a long distance flight, or drinking a glass of beer that comes from certain areas with high levels of natural background radiation.

Here's a good chart from the nytimes that shows how much radiation has been released thus far:

http://www.nytimes.com/interactive/2011/03/16/world/asia/20110316-japan-quake-radiation.html?ref=asia

peak levels (measured in units/hr) have passed the typical annual US dose from all sources (units/year) three times since the #2 reactor exploded.

Who the fuck is Barry Brook, anyhow?

Also, here is a good Q and A site that addresses a lot of the questions that have come up in the discussion here:

http://green.blogs.nytimes.com/2011/03/16/q-and-a-on-the-nuclear-crisis-in-japan/?hp

joshua, that cut & paste is waay behind events. The person who wrote that was talking out of his ass.

His original included assertions that Japan's reactors have core-catchers, but they do not.

Additionally, they do not have hydrogen dispersers (modern plants have diesel spark plugs to burn off accumulating hydrogen in the containment shell). This is why Units 1 and 3 blew up, and possibly why Unit 2 blew up (it is unclear if Unit 2's secondary pressure vessel failed due to a hydrogen explosion or just steam overpressure).

The Japanese government is saying Units 2 and 3 have lost partial containment -- the suppression pool pressure vessel may be compromised, meaning any seawater injections they are doing into the core when bled out the primary vessel (housing the reactor core) will be lost to the environment through these breaches.

This is simply unprecedented -- containment has been lost in at least two reactors, one of which has 5% plutonium.

Adding to the joy is that seawater impurities will get irradiated and increase the contamination. All this water they're injecting is turning to radioactive steam and they don't have any place to put it.

They've stopped updating the public on radiation levels within the plant, frankly I think they are approaching deadly levels, just from the steam venting.

Additionally, there's the spent fuel issue in Unit 4 -- it may have been out of service but its core was actually relocated OUTSIDE the containment and was in the used fuel pool, along with about 5 years worth of other spent fuel.

They are saying they've lost cooling on that too, and Unit 4's containment shell is not looking too good right now for a building that is supposed to be cooling so much fissionable stuff.

it's the one on the left here:

Unit 3's spent fuel is also apparently exposed (the Unit 3 explosion was a doozy), so that's two quantities of fissionable material exposed to the open air.

Units 5 & 6 temperatures are going up but if they can run a power line to them maybe they can be saved.

Here's a picture I took from Japanese TV today:

See those two tanks in the center? Those were the diesel generator tanks.

Real intelligent place to put your primary backup fuel, 150 miles from a very active subduction fault that has generated deadly tsunamis in living memory.