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Looking at most of the bad information out there about the ongoing incident I decided to post up this fact sheet (which has been verified by my own independent research) regarding the ongoing nuclear incident in Japan. I would also like to use this as a live blog to update the community with news as I see it on NHK and Japanese news sources. I have noticed that the western media is about 24 hours behind on their reporting.

The source of the fact sheet was originally found as a comment on the MSNBC website by a user by the name of Sam W. I found it the best all in one breakdown of what is happening right now and what might happen in the near future.

What is going on here?

In the aftermath of the recent earthquake and tsunami in Japan, two nuclear power stations on the east coast of Japan have been experiencing problems. They are the Fukushima Daiichi ("daiichi" means "number one") and Fukushima Daini ("number two") sites, operated by the Tokyo Electric Power Company (or TEPCO). Site one has six reactors, and site two has four. The problematic reactors are #1, #2, and #3 at site one, which are the oldest of the ten and were due to be decommissioned this year.
In short, the earthquake combined with the tsunami have impaired the cooling systems at these reactors, which has made it difficult for TEPCO to shut them down completely. Reactor #1 is now considered safe after crew flooded the reactor with sea water. Reactor #3 was starting this process as this was originally written (6:00PM CST/11:00PM GST on March 13th). Site crew began preparing to add sea water to reactor #2 around 7:30AM GMT on March 14th, if a cooling procedure does not work.
The four reactors at site two did not have their systems impaired and have shut down normally.

Can this cause a nuclear explosion?

No. It is physically impossible for a nuclear power station to explode like a nuclear weapon.
Nuclear bombs work by causing a supercritical fission reaction in a very small space in an unbelievably small amount of time. They do this by using precisely-designed explosive charges to combine two subcritical masses of nuclear material so quickly that they bypass the critical stage and go directly to supercritical, and with enough force that the resulting supercritical mass cannot melt or blow itself apart before all of the material is fissioned.
Current nuclear power plants are designed around subcritical masses of radioactive material, which are manipulated into achieving sustained fission through the use of neutron moderators. The heat from this fission is used to convert water to steam, which drives electric generator turbines. (This is a drastic simplification.) They are not capable of achieving supercritical levels; the nuclear fuel would melt before this could occur, and a supercritical reaction is required for an explosion to occur.
Making a nuclear bomb is very difficult, and it is completely impossible for a nuclear reactor to accidentally become a bomb. Secondary systems, like cooling or turbines, can explode due to pressure and stress problems, but these are not nuclear explosions.

Is this a meltdown?

Technically, yes, but not in the way that most people think.
The term "meltdown" is not used within the nuclear industry, because it is insufficiently specific. The popular image of a meltdown is when a nuclear reactor's fuel core goes out of control and melts its way out of the containment facility. This has not happened and is unlikely to happen.
What has happened in reactor #1 and #3 is a "partial fuel melt". This means that the fuel core has suffered damage from heat but is still largely intact. No fuel has escaped containment. Core #2 may have experienced heat damage as well, but the details are not known yet. It is confirmed that reactor #2's containment has not been breached.

How did this happen? Aren't there safety systems?

When the earthquakes in Japan occurred on March 11th, all ten reactor cores "scrammed", which means that their control rods were inserted automatically. This shut down the active fission process, and the cores have remained shut down since then.
The problem is that even a scrammed reactor core generates "decay heat", which requires cooling. When the tsunami arrived shortly after the earthquake, it damaged the external power generators that the sites used to power their cooling systems. This meant that while the cores were shut down, they were still boiling off the water used as coolant.
This caused two further problems. First, the steam caused pressure to build up within the containment vessel. Second, once the water level subsided, parts of the fuel rods were exposed to air, causing the heat to build up more quickly, leading to core damage from the heat.

What are they doing about it?

From the very beginning, TEPCO has had the option to flood the reactor chambers with sea water, which would end the problems immediately. Unfortunately, this also destroys the reactors permanently. Doing so would not only cost TEPCO (and Japanese taxpayers) billions of dollars, but it would make that reactor unavailable for generating electricity during a nationwide disaster. The sea water method is a "last resort" in this sense, but it has always been an option.
To avoid this, TEPCO first took steps to bring the cooling systems back online and to reduce the pressure on the inside of the containment vessel. This involved bringing in external portable generators, repairing damaged systems, and venting steam and gases from inside the containment vessel. These methods worked for reactor #2 at site one, prior to complications; reactors four through six were shut down before for inspection before the earthquake hit.
In the end, TEPCO decided to avoid further risk and flooded reactor #1 with sea water. It is now considered safely under control. Reactor #3 is currently undergoing this process, and reactor #2 may undergo it if a venting procedure fails.
The four reactors at site two did not have their external power damaged by the tsunami, and are therefore operating normally, albeit in a post-scram shutdown state. They have not required any venting, and reactor #3 is already in full cold shutdown.

Is a "China Syndrome" meltdown possible?

No, any fuel melt situation at Fukushima will be limited, because the fuel is physically incapable of having a runaway fission reaction. This is due to their light water reactor design.
In a light water reactor, water is used as both a coolant for the fuel core and as a "neutron moderator". What a neutron moderator does is very technical (you can watch a lecture which includes this information here), but in short, when the neutron moderator is removed, the fission reaction will stop.
An LWR design limits the damage caused by a meltdown, because if all of the coolant is boiled away, the fission reaction will not keep going, because the coolant is also the moderator. The core will then only generate decay heat, which while dangerous and strong enough to melt the core, is not nearly as dangerous as an active fission reaction.
The containment vessel at Fukushima should be strong enough to resist breaching even during a decay heat meltdown. The amount of energy that could be produced by decay heat is easily calculated, and it is possible to design a container that will resist it. If it is not, and the core melts its way through the bottom of the vessel, it will end up in a large concrete barrier below the reactor. It is nearly impossible that a fuel melt caused by decay heat would penetrate this barrier. A containment vessel failure like this would result in a massive cleanup job but no leakage of nuclear material into the outside environment.
This is all moot, however, as flooding the reactor with sea water will prevent a fuel melt from progressing. TEPCO has already done this to reactor #1, and is in the process of doing it to #3. If any of the other reactors begin misbehaving, the sea water option will be available for those as well.

What was that explosion?

One of the byproducts of reactors like the ones at Fukushima is hydrogen. Normally this gas is vented and burned slowly. Due to the nature of the accident, the vented hydrogen gas was not properly burned as it was released. This led to a build up of hydrogen gas inside the reactor #1 building, but outside the containment vessel.
This gas ignited, causing the top of the largely cosmetic external shell to be blown off. This shell was made of sheet metal on a steel frame and did not require a great deal of force to be destroyed. The reactor itself was not damaged in this explosion, and there were only four minor injuries. This was a conventional chemical reaction and not a nuclear explosion.
You see what happened in the photo of the reactor housing. Note that other than losing the sheet metal covering on the top, the reactor building is intact. No containment breach has occurred.
At about 2:30AM GMT on March 14th, a similar explosion occurred at the reactor #3 building. This explosion was not unexpected, as TEPCO had warned that one might occur. The damage is still being assessed but it has been announced that the containment vessel was not breached and that the sea water process is continuing.
Around 7:30AM GMT on March 14th, it was announced that the explosion at reactor #2 has damaged the already limping cooling systems of reactor #2. It may also receive the sea water treatment if they are unable to use a venting procedure to restart the cooling systems.

Is there radiation leakage?

The radiation levels outside the plant are higher than usual due to the release of radioactive steam. These levels will go down and return to their normal levels, as no fuel has escaped containment.
For perspective, note that charts detailing detrimental radiation exposure start at 1 Gy, equivalent to 1 Sv; the radiation outside the problematic Fukushima reactors is being measured in micro-Svs per hour. The highest reported levels outside the Fukushima reactors has been around 1000 to 1500 micro-Svs per hour. This means that one would have to stay in this area for four to six weeks, 24 hours a day, without protection in order to experience the lowest level of radiation poisoning, which while unpleasant is not normally fatal. And this level will not stay where it is.
Also note the chart of normal radiation exposure levels from things like medical x-rays and airline flights.
There have also been very minor releases of radioactive reactor byproducts like iodine and cesium along with the steam. This material is less radioactive than the typical output of coal power plants. It is significant mainly as an indicator of the state of the reactor core.
I read that there's a plume of radioactive material heading across the Pacific.
In its current state, the steam blowing east from Japan across the pacific is less dangerous than living in Denver for a year. If it makes it across the ocean, it will be almost undetectable by the time it arrives, and completely harmless as the dangerous elements in the steam will have decayed by then.
What's this about fuel rods being exposed to the air?
When the coolant levels inside the reactor get low enough, the tops of the fuel rods will be exposed to the air inside the containment vessel. They have not been exposed to the external atmosphere and the containment vessels are all intact.

Can this end up like Chernobyl?

No, it cannot. for several reasons.
Chernobyl used graphite as a neutron moderator and water as a coolant. For complicated reasons, this meant that as the coolant heated up and converted to steam, the fission reaction intensified, converting even more water to steam, leading to a feedback effect. The Fukushima reactors use water as both the coolant and the neutron moderator, which means that as the water heats up and converts to steam, the reaction slows down instead. (The effect of the conversion of water coolant to steam on the performance of a nuclear reactor is known as the "void coefficient", and can be either positive or negative.)
Chernobyl was designed so that as the nuclear fuel heated up, the fission reaction intensified, heating the core even further, causing another feedback effect. In the Fukushima reactors, the fission reaction slows down as the fuel heats up. (The effect of heating of the nuclear fuel on the performance of a nuclear reactor is known as the "temperature coefficient", and can also be positive or negative.)
Chernobyl's graphite moderator was flammable, and when the reactor exploded, the radioactive graphite burned and ended up in the atmosphere. The Fukushima reactors use water as a neutron moderator, which is obviously not flammable.
Note that while Chernobyl used light water as a coolant (as distinct from heavy water), it was not a "light water reactor". The term LWR refers strictly to reactors that use light water for both cooling and neutron moderation.
The news said this was the worst nuclear power accident since Chernobyl, though.
It's the only nuclear power plant accident of its type since Chernobyl. It's easy to be the worst in a sample size of one.

Is this like Three Mile Island?

There are similarities. The final effect on the world is likely to be similar: no deaths, minimal external contamination, and a tremendous PR disaster for the nuclear industry due to bad reporting by the media.

How can I keep up with developments?

The western media has been very bad about reporting this event, due to a combination of sensationalist reporting, ignorance, and the use of inexact or unexplained terminology.
One of the safe sources of information is the TEPCO site, which has been posting press releases on a regular basis. Unfortunately, this site is often unresponsive due to the immense traffic it is receiving.
The important thing to remember is that most of the "experts" appearing on the news are engaging in speculation. Very few of them are restricting themselves to what they can be sure about, and those that are have often been misrepresented.

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Comment Preferences

  •  Thanks for this summary (1+ / 0-)
    Recommended by:

    Can you provide a link on this statemen specifically:

    Reactor #1 is now considered safe after crew flooded the reactor with sea water.

    I don't read Japanese but if confirmed that would go a long way to helping me sleep at night.

  •  Please listen to this presser (0+ / 0-)

    I don't know this persons position with the government or whether you will want to assign him much credibility, however, he appears to be the first person to be telling the truth.  

    Every moment in life contains an off ramp. Never be afraid to use it.

    by Adept2u on Mon Mar 14, 2011 at 07:19:06 AM PDT

  •  Follow quake headlines from Kyodo news agency here (9+ / 0-)

    Normally you must be an institutional subscriber to use the Kyodo news site directly, but for this event they are making an exception (hence the tagline "now fully accessible").

    The Dutch kids' chorus Kinderen voor Kinderen wishes all the world's children freedom from hunger, ignorance, and war.

    by lotlizard on Mon Mar 14, 2011 at 07:20:13 AM PDT

  •  Thank you for your report. (1+ / 0-)
    Recommended by:

    Factual information is a good thing!

    I blog on healthcare issues for Tikkun Daily as Lauren Reichelt.

    by TheFatLadySings on Mon Mar 14, 2011 at 07:35:16 AM PDT

  •  Latest information (9+ / 0-)

    This information was collected at 10:00AM EDT:

    AJE Liveblog:
    (Local time in Japan)

    A quick roundup of what's been going on in the past few hours.

    - Fukushima has been hit by another explosion. Saturday's blast was at No.1 reactor - this morning's was at No.3 reactor. It injured 11 people.

    - Coolant at Fukushima's No.2 reactor has run out, meaning its fuel rods have become fully exposed, causing temperatures to rise swiftly, and pressure inside the reactor core to mount rapidly.

    - US warships brought in to aid the relief effort have reportedly been moved away from the coast after detecting elevated radiation levels.

    - France has reportedly asked its citizens to leave the Tokyo area and "strongly advised" French nationals against travel ro Japan.

    - Japanese officials appeal for calm, say any other explosions or meltdowns are unlikely. "The figures do not indicate a high level of radiation," says Japan's cabinet secretary.

    BBC Liveblog:
    (GMT time)

    1431: More from Japanese nuclear engineer Masashi Goto: He say that as the reactor uses mox (mixed oxide) fuel, the melting point is lower than that of conventional fuel. Should a meltdown and an explosion occur, he says, plutonium could be spread over an area up to twice as far as estimated for a conventional nuclear fuel explosion. The next 24 hours are critical, he says.
    1426: Mr Goto says his greatest fear is that blasts at number 3 and number 1 reactors may have damaged the steel casing of the containment vessel designed to stop radioactive material escaping into the atmosphere. More to follow.
    1422: Japanese engineer Masashi Goto, who helped design the containment vessel for Fukushima's reactor core, says the design was not enough to withstand earthquakes or tsunamis and the plant's builders, Toshiba, knew this. More on Mr Goto's remarks to follow.
    1415: Prof Richard Wakeford adds: "The other thing authorities [in Japan] will be considering is the issuing of stable iodine tablets to block the intake of radioactive iodine which accumulates in the thyroid, and which is particularly problematic if it happens in young children."
    1406: Concerns about a possible radiation leak from the Fukushima plant have sparked a run on iodine tablets in Finland, AFP reports. The country's nuclear safety chiefs say there is no need for people there to be buying iodine

    1354: Asked if there is a danger of a meltdown at the Fukushima plant, nuclear safety expert Toshihiro Bannai adds: "On units one and three there is a possibility they are partially damaged in the core. However at this point, monitoring indications doesn't indicate damage of the core."

    1347: Toshihiro Bannai, a director at the Japanese Nuclear and Industrial Safety Agency, tells BBC Radio 4's World at One programme that the situation at the Fukushima plant is not good, but it is "stable".

    1229: A major explosion is unlikely at Fukushima's Number 2 reactor, Kyodo news agency quotes a government spokesman as saying, adding that seawater is being pumped in to stabilise it.

    1224: A quick summary of the nuclear crisis in Japan: The nuclear emergency following Friday's earthquake and tsunami has worsened, with the operators of the damaged Fukushima nuclear plant warning that they can't rule out a possible meltdown. The company says it's possible that cooling water at the number two reactor has evaporated, exposing the nuclear fuel rods. The BBC environment correspondent Richard Black says such an outcome would be very serious.

    1125: Worrying news, this: The operators of the damaged Fukushima nuclear plant say it's possible that cooling water at one of the reactors has evaporated, Reuters reports. The company says it can't rule out the possibility that the nuclear fuel rods in Number 2 reactor were now exposed and could be at risk of meltdown.

    Kyodo Headlines:
    (Local time in Japan)
    22:15 14 March NEWS ADVISORY: Fuel rods at No. 2 reactor fully exposed for about 2.5 hours: agency

    21:53 14 March BREAKING NEWS: Water level of about 2 meters recovered at No. 2 reactor of nuke plant

    21:41 14 March BREAKING NEWS: Fukushima's 3 reactors highly likely facing melting: Edano

    21:37 14 March NEWS ADVISORY: Worst-scenario for Fukushima plant unlikely to be like Chernobyl: Edano

    21:23 14 March NEWS ADVISORY: Radiation around nuke plant at tolerable level for humans: Edano

    21:16 14 March NEWS ADVISORY: Ongoing work to cool No. 2 reactor hoped to stabilize situation: Edano

    21:16 14 March BREAKING NEWS: No. 2 reactor's big explosion unlikely: Edano

    21:12 14 March Fukushima No. 2 reactor's fuel rods fully exposed, melting feared

    21:09 14 March NEWS ADVISORY: Seawater pumping resumes at 2 reactors of Fukushima nuke plant: Edano

    21:08 14 March BREAKING NEWS: Fuel rods of No. 2 reactor of Fukushima plant may have partially melted: TEPCO

    20:57 14 March NEWS ADVISORY: Steam being released at No. 2 reactor of Fukushima nuke plant

    20:54 14 March NEWS ADVISORY: Top gov't spokesman Edano to meet press around 9 p.m.

    20:17 14 March NEWS ADVISORY: Water level of 30 centimeters recovered at No. 2 reactor of nuke plant

    20:16 14 March URGENT: Fuel rods at No. 2 reactor of Fukushima No. 1 nuke plant fully exposed

    19:58 14 March FLASH: Fuel rods at No. 2 reactor of Fukushima No. 1 nuke plant fully exposed

    19:50 14 March Cooling functions fail at Fukushima No. 2 nuclear reactor

    19:39 14 March BREAKING NEWS: Fuel rods at No. 2 reactor of Fukushima No. 1 nuke plant partially exposed

    BBC News article:

    Meltdown alert at Japan reactor

    Technicians are battling to stabilise a third reactor at a quake-stricken Japanese nuclear plant, which has been rocked by a second blast in three days.

    The Fukushima Daiichi plant's operators have resumed pumping seawater into reactor 2 after a cooling system broke.

    They warned of a possible meltdown when the fuel rods became exposed after the pump stopped as its fuel ran out.

    A cooling system breakdown preceded explosions at the plant's reactor 3 on Monday and reactor 1 on Saturday.

  •  IAEA Update (10+ / 0-)

    They have a facebook page where they are posting updates:

    Fukushima Daiichi Nuclear Power Plant

    Japanese authorities have reported to the IAEA that Fukushima Daiichi Unit 2 has experienced decreasing coolant levels in the reactor core.  Officials have begun to inject sea water into the reactor to maintain cooling of the reactor core.

    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.

    Evacuation Status

    On 12 March, the Japanese Prime Minister ordered the evacuation of residents living within 10 kilometres of the Fukushima Daini nuclear power plant and within 20 kilometres of the Fukushima Daiichi nuclear power plant.  Japan’s Nuclear and Industrial Safety Agency (NISA) has reported that about 185,000 residents had been evacuated from the towns listed below as of 13 March, 17:00 (JST).

    Populations of evacuated towns near the affected nuclear power

    Hirono-cho                   5,387

    Naraha-cho                  7,851

    Tomioka-cho              15,786

    Okuma-cho                11,186

    Futaba-cho                   6,936

    Namie-cho                  20,695

    Tamura-shi                41,428

    Minamisouma-shi      70,975

    Kawauchi-mura          2,944

    Kuzuo-mura                1,482

    Total                         184,670

    Iodine Distribution

    Japan has distributed 230,000 units of stable iodine to evacuation centres from the area around Fukushima Daiichi and Fukushima Daini nuclear power plants, according to officials. The iodine has not yet been administered to residents; the distribution is a precautionary measure in the event that this is determined to be necessary.

    The ingestion of stable iodine can help to prevent the accumulation of radioactive iodine in the thyroid.

    Weather forecast

    In partnership with the World Meteorological Organization, the IAEA is continuing to monitor weather forecasts and is providing updates to member states.  Since the incident began, winds have been moving away from the Japanese coast to the East, and predictions call for the same patterns to persist for the next three days.

    The IAEA continues to liaise with the Japanese authorities and is monitoring the situation as it evolves.

    •  Link to Fukushima weather stations: (1+ / 0-)
      Recommended by:

      Tohoku region, Fukushima prefecture itself:
       JMA Table of Hourly Weather Observations
      Other links from that page.
      Hard to judge distance, fairly small scale map, no towns listed above shown, just places with WX stations.
      Fukushima station gives wind readings, bears watching.

      "Double, double, toile and trouble; Fire burne, and Cauldron bubble... By the pricking of my Thumbes, Something wicked this way comes": Republicans Willkommen auf das Vierte Reich! Es ist nicht mehr Angelegenheit.

      by Bluefin on Mon Mar 14, 2011 at 10:52:35 AM PDT

      [ Parent ]

  •  Great diary (4+ / 0-)

    Thanks for a straightforward factual diary about what is going on, and the worst-case scenarios, as well as the likely-case scenarios.

    Minority rights should never be subject to majority vote.

    by lostboyjim on Mon Mar 14, 2011 at 07:50:24 AM PDT

  •  The Problem was Generator Location (0+ / 0-)

    The New York Times has an article quoting top seismic sturctural expert Peter Yanev stating that the problem stems from the seawalls.... that the seawalls gave the plant operators a sense of confidence that the backup generators could be located at ground level...  

    The plants operated as designed...the sensors detected the quake and shut down the core... the problem stems from the loss of cooling, which was supposed to be covered by the generators.... .

  •  Radiation safety-what about kids? (2+ / 0-)
    Recommended by:
    DRo, dirtfarmer

    I have to ask questions every time radiation exposure safety is not broken down according to adults vs. children.....pregnant women, embryo, fetus, etc. because NO WAY are adults and kids equivalent here.

    Also, read the diary:

    Also, isn't there a difference between contaminants on skin vs. inhaled, ingested?

    Meanwhile, any news about independent sources of reporting on radiation around Japanese plants? I heard something briefly on French the chart on one Geiger counter and much higher than official reports on two others.

  •  Thanks for putting this together (0+ / 0-)

    It sounds like, from the latest reports, that they're not able to get water on the damaged reactors. We may yet find out how good the containment structures are.

    "No special skill, no standard attitude, no technology, and no organization - no matter how valuable - can safely replace thought itself."

    by xaxnar on Mon Mar 14, 2011 at 02:19:30 PM PDT

  •  Kudos! (2+ / 0-)
    Recommended by:
    worldlotus, JJG Miami Shores

    Before I saw this diary, and frustrated by the volume of misinformation flooding over dKos, I wrote up my own explanation, which I now think inferior to yours. I very much hope this garners enough recommendations to get noticed.

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