Japanese earthquake / tsunami discussion

Helix

opinion guy wrote: »

This is a stupid argument. This situation has never before arisen. What would he have them do once they find its not in the rule book. Go home and catch up on their sleep ?

he's not saying it as a dig, hes saying it as a matter of fact statement about what's happening

3ndahalfof6

interesting there was a 4.5 in the Taiwan region, it is the 1st I have noticed in that area.

dreamer_ire

Quake-hit Japan faces a recovery and reconstruction bill of at least $180 billion, or 3 percent of its annual economic output and more than 50 percent higher than the total cost of 1995's earthquake in Kobe.
Even though some extreme projections of the longer-term cost look at figures closer to $1 trillion over several years, more standard tallies akin to those used after the Kobe quake hover around this level.

http://www.reuters.com/article/2011/03/14/us-japan-economy-costs-idUSTRE72D60C20110314

Turtwig

The Sparrow wrote: »

Another update from Michio Kaku:

.

* Radiation levels have soared. Several workers have shown full blown symptoms of radiation sickness (probably indicating that they absorbed perhaps tens of thousands of X-ray equivalents).

Radiation levels have not "soared". The radiation sickness is unfortunately more down to the fact that these workers have been exposed to low levels for over 48 hours now.

* Unit 3 contains MOX fuel (mixed oxide fuel) which contains plutonium, which is one of the most toxic chemicals known to science. So a possible meltdown there might spread this deadly chemical as well.

I'm a little confused by this statement. I was under the impression all Uranium fuels become MOX eventually.

* The state of the nuclear waste units is unclear so there is always the possibility that the huge nuclear waste contained in these storage units might escape.

This is actually what I'm most worried about currently there has been no mention of condition this by Tepco.

Jack Sheehan

Someone (not me) has made an excellent megapost in the SA forums, so I'm just going to quote it all here. It clears up a lot of the issues surrounding the nuclear accident, and frankly, is hella reassuring:

What in the hell 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 this about an 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 this photo. 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.

Here is a chart showing the effects of various radiation poisoning levels. For perspective, note that this chart starts 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.

Where can I find more information about these issues?

Reading:

Timeline and data sheets for the incident by the Nuclear Energy Institute
The International Atomic Energy Agency is providing regular announcements
Wikipedia on light water reactors and nuclear weapon design
The United States Nuclear Regulatory Commission's Boiling Water Reactor (BWR) Systems manual - the Fukushima reactors are BWRs, a subset of LWRs
More about BWRs
Tokyo Electric Power Company site with press releases - currently hard to reach due to traffic

Video:

"Physics for Future Presidents" lecture ten, on nuclear weapons and nuclear reactors
Footage of the hydrogen explosion at reactor #1

Photos:

before and after satellite photos of Fukushima site one

Original post, with proper links and photos: http://forums.somethingawful.com/showthread.php?threadid=3396817&pagenumber=1

Jack Sheehan

Zayden Hallowed Bayonet wrote: »

Fair play to the workers trying their best at a bad situation. Does it mean they are damaged now forever being exposed?

No. The level of exposure the workers have received is well below the level the level that would cause damage. As one person put it, its like having a couple of x rays. In addition, they are wearing protective gear.

It was reported that the crew aboard the U.S.S. Ronald Reagan sailed through a radioactive cloud today. That was true. What was less widely reported was that the solution was to wash themselves with soap and water. The level of radioactive exposure was tiny, about a months worth of natural exposure.

Rob A. Bank

Jack Sheehan wrote: »

It was reported that the crew aboard the U.S.S. Ronald Reagan sailed through a radioactive cloud today. That was true. What was less widely reported was that the solution was to wash themselves with soap and water. The level of radioactive exposure was tiny, about a months worth of natural exposure.

How do you wash your lungs ?

Turtwig

Jack Sheehan wrote: »

No. The level of exposure the workers have received is well below the level the level that would cause damage.r.

This is isn't exactly true. Yes the radiation levels have been low but the exposure time for the workers has been continuously increasing. Level's this afternoon were 15 mSv /hr and exposure adds up.

Rob A. Bank

1820: The French ASN nuclear safety authority says the incident at the Fukushima plant could be classed as level 5 or 6 on the international scale of 1 to 7. It is currently rated at level 4.


That would make this incident the second worst nuclear accident ever.

Chernobil was a 7.

maquiladora

They have resumed injecting seawater for No. 2 now, I guess they got that valve open again. Those lads are really earning their wages.

shadowninty

Rob A. Bank wrote: »

How do you wash your lungs ?

I'd be much more worried about the toxic fumes from fossil fuels they breath in every day

darkman2

BBC

#
1849: A 5.7 magnitude aftershock has just shaken the north-east of Japan, the US Geological Survey reports.


1844: Mikan in Tokyo writes: "There is a growing sense that the Japanese government is not telling us the true story. On one end, there is the Japanese media that plays down the nuclear drama and focuses on human drama, and at the other, the foreign media is up-playing the nuclear disaster. In my company I heard at least half the essential staff is being sent to Hong Kong, Singapore or even Sydney. I am preparing to leave Tokyo and/or Japan. So are many of my friends. There is a sense of deserting Tokyo as soon as possible."

opinion guy

Helix wrote: »

he's not saying it as a dig, hes saying it as a matter of fact statement about what's happening

Well it seemed to carry an air of disapproval to me.

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.

This does not make sense to me. The job of the moderator is to absorb neutrons. If you remove the moderator the reaction should speed up, not slow down.

Jack Sheehan

Rob A. Bank wrote: »

How do you wash your lungs ?

You dont. You dont need to. The amount of dust you inhale would be tiny. Washing dust from your clothes and skin would be pretty much a precaution.

Malty_T wrote: »

This is isn't exactly true. Yes the radiation levels have been low but the exposure time for the workers has been continuously increasing. Level's this afternoon were 15 mSv /hr and exposure adds up.

Absolutely true, but most of the workers are within protected control rooms, and wearing protective clothing. I'm not saying that no one will be affected in the end but this isn't the Russians sending those poor firefighters in or anything.

Rob A. Bank wrote: »

1820: The French ASN nuclear safety authority says the incident at the Fukushima plant could be classed as level 5 or 6 on the international scale of 1 to 7. It is currently rated at level 4.


That would make this incident the second worst nuclear accident ever.

Chernobil was a 7.

Eh, this is kind of a misnomer. There have been incidents classed as five and six before, and the scale is logarithmic. Each level represents an incident approximately ten times worse than the one below it. We will have to wait to see if it is reclassified to a 5 or 6. No one has been killed so far, thank god, and hopefully no one will be.

Helix

opinion guy wrote: »

Well it seemed to carry an air of disapproval to me.

you took it up wrong

andrew

opinion guy wrote: »

This does not make sense to me. The job of the moderator is to absorb neutrons. If you remove the moderator the reaction should speed up, not slow down.

Neutrons released when a Uranium atom is split need to be slowed down before they can react with other Uranium atoms. The moderator slows down the neutrons so that they can react. The job of the control rods, however, is to absorb neutrons.

Turtwig

Jack Sheehan wrote: »

Absolutely true, but most of the workers are within protected control rooms, and wearing protective clothing. I'm not saying that no one will be affected in the end but this isn't the Russians sending those poor firefighters in or anything.

Oh yes, each time I think of the Russian Workers forced to keep Reactor 3 functional and supplying power while its and reactor four's roofs burned I die a little inside. Chernobyl was a f**king disgrace and served as dire indicator of everything wrong with the soviet way of doing things.:mad:

opinion guy wrote: »

This does not make sense to me. The job of the moderator is to absorb neutrons. If you remove the moderator the reaction should speed up, not slow down.

The moderators main purpose is not to absorb neutrons though it will invariably absorb some.
Its job is to slow down the high energy neutrons by collisions with its nuclei because lower energy neutrons are more likely to be absorbed by the uranium. If you remove the moderator you are effectively making it harder for the uranium to absorb neutrons and in turn making it less likely to produce further fissions.

(Not sure where my previous post went...:o)

Hendrixfan

I cant get onto Google or Wikipedia no more.

opinion guy

Hendrixfan wrote: »

I cant get onto Google or Wikipedia no more.

This isn't a helpdesk its a thread about the Japanese disasters

Rob A. Bank

Jack Sheehan wrote: »

I'm not saying that no one will be affected in the end but this isn't the Russians sending those poor firefighters in or anything

As I understand it they are using firefighting equipment to pump the seawater into the reactors and several workers have being treated for radiation sickness already.

So in the future we may see monuments to firefighters like the Chernobil one in Japan too.

http://mexicanskies.com/archives/chernobyl%20memorial.JPG

.

Dempsey

Malty_T wrote: »

The moderators main purpose is not to absorb neutrons though it will invariably absorb some.
Its job is to slow down the high energy neutrons by collisions with its nuclei because lower energy neutrons are more likely to be absorbed by the uranium. If you remove the moderator you are effectively making it harder for the uranium to absorb neutrons and in turn making it less likely to produce further fissions.

(Not sure where my previous post went...:o)

http://www.tepco.co.jp/en/press/corp-com/release/11031220-e.html

Control rods are fully inserted to slow/stop the reaction

lucozader

imagine the bravery of working in such a dangerous environment, i would not turn up for work if it was me...

maquiladora

Jack Sheehan wrote: »

Absolutely true, but most of the workers are within protected control rooms, and wearing protective clothing. I'm not saying that no one will be affected in the end but this isn't the Russians sending those poor firefighters in or anything.

One worker was killed by the first explosion at the No. 1 reactor building.

http://www.bloomberg.com/news/2011-03-12/tokyo-electric-tries-to-cool-unstable-reactors-avert-three-mile-island-.html

Lirange

This video explains the problems at the Fukushima plant really well. The best explanation I've seen.

http://www.cnn.com/video/#/video/world/2011/03/14/dnt.japan.reactor.explainer.nhk?hpt=C2

maquiladora

Tepco are holding another press conference, its the middle of the night over there, cant find a stream with English translation.

Only info from twitter so far.

According to TEPCO press conference just now, pressure valve released and water now entering #2, but water level not rising - not sure why

Duiske

davyjose wrote: »

Joking aside, the logistics are impossible. To get them deep enough so they are below the water table is next to impossible, and not financially viable at all.

Exactly. Over the long run, despite it's risks and initial start-up costs, nuclear powered plants are a cheaper option than fossil fuel burning plants. If you increase the cost's of nuclear you make fossil fuels a more financially viable option, but then, because of increased demand for oil, coal and gas, these cost's also start to spiral. I guess the cost's would find a happy medium at some stage, but by then you would probably be paying 3 euro a litre or more to fill your car or home heating tank.

By the way, something I read today really struck me. Not sure how true this is, but it seem's that in the past 2 year's, more people have died in accidents during the installation of wind turbines than have ever been killed due to nuclear accidents. No doubt that figure came from the pro-nuclear lobby though. Who else would bother even looking into it ?

kona

lucozader wrote: »

imagine the bravery of working in such a dangerous environment, i would not turn up for work if it was me...

dreamer_ire

Jack Sheehan wrote: »

Someone (not me) has made an excellent megapost in the SA forums, so I'm just going to quote it all here. It clears up a lot of the issues surrounding the nuclear accident, and frankly, is hella reassuring:

Original post, with proper links and photos: http://forums.somethingawful.com/showthread.php?threadid=3396817&pagenumber=1

Thanks for that Jack, great post. What I don't get is the western media's agenda for hype. I understand that they want viewers rather than the competion getting them but why is work like this article not being reported?

Turtwig

Lirange wrote: »

This video explains the problems at the Fukushima plant really well. The best explanation I've seen.

http://www.cnn.com/video/#/video/world/2011/03/14/dnt.japan.reactor.explainer.nhk?hpt=C2

Very well done. Now Sky and Fox and Rte pls just loop that video over and over again instead of this pointless fear mongering speculation.

Lirange

opinion guy wrote: »

This is a stupid argument. This situation has never before arisen. What would he have them do once they find its not in the rule book. Go home and catch up on their sleep ?

Just because this situation has never occurred before does not mean that it should not have been anticipated and planned for in advance. I think the point he was making is that it should have been in the rule book.