Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[robinson]

One of the many things about the ongoing disasters in Japan is the almost complete lack of data about the most simple and easy to achieve measurements.

Like what is in the constant steam coming out of a reactor building. Or what's left of one. You would think there doesn't exist the technological ability to put sensors in the steam to measure the radioactivity and materials coming out a ruined reactor, or ruined fuel ponds.

That sort of information would seem important to my simple mind. Yet I have never, since day one, even heard of a discussion about it. (I may have missed it here of course).

It just seems (again, to my simple mind) that knowing what is coming out of steaming nuclear pile of rubble would be important. Especially to the people working nearby. But I imagine anyone downwind would also want to know.

Sometimes (usually at night) I see these huge steam clouds escaping into the air. We know it's from melted fuel rods, we know melted nuclear fuel rods are dangerous, so why no data on what is simply going into the air, 24/7?

Is that too much to ask?

 

[elektrownik]

The following article is reporting the detailed contamination data...

http://www.yomiuri.co.jp/national/news/20110603-OYT1T00778.htm

NHK article: http://www3.nhk.or.jp/daily/english/03_32.html

 

[Bandit127]

No, yes, no yes, Maybe?

http://nuclearstreet.com/nuclear_power_industry_news/b/nuclear_power_news/archive/2011/06/01/tepco-starts-spent_2d00_fuel-cooling-system-at-fukushima-unit_2c00_-reports-oil-leak-060102.aspx"

Congratulations to the people at the sharp end of this situation.

It may only be a small solution in a mass of big problems, but the establishment of closed loop cooling for the SFP in Unit 2 is a turning point I think and it gives me a sense of optimisim that we will have improved success in working our way through this.

No more radiation washed out or steamed off of at least part of the site.

Good news.

 

[zapperzero]

The following article is reporting the detailed contamination data for the two nuclear power plant operators previously reported ( page 531 of this thread : https://www.physicsforums.com/showthread.php?p=3329327#post3329327 ) as "may exceed the 250 mSv limit" :

The 30 year old one has 210~580 mSv of internal contamination adding to the 74 mSv external contamination.

The 40 year old one has 200~570 mSv adding to 89 mSv.

http://www.yomiuri.co.jp/national/news/20110603-OYT1T00778.htm

Is this total dose so far? Expected total lifetime dose? Or what?

 

[etudiant]

The NHK writeup here http://www3.nhk.or.jp/daily/english/03_32.html indicates that most of the internal dose was concentrated in the thyroid gland.
That suggests iodine contamination. Hopefully, that means the incremental dose beyond this point will be small, given the short half life of the iodine 131.
Against that, it also probably means most of the early responders are in the same boat, with 250+ mSv thyroid doses. TEPCO did not hand out potassium iodide pills to the first responders afaik.

 

[Bioengineer01]

It's a waiting game. Chernobyl timeline is another 125 years (give or take) before the remnants of the melted core (corium) can be approached for removal because to this day it is so radioactive.

Here you have 3 cores melted down awaiting enough time to elapse for cooling down just to begin containment, let alone worry about where all the contaminated cooling water ends up.

If the design works for the corium then its path is meant to flow to the bottom of the secondary containment (drywell), spread out, sit there and cool down. Bottom of the drywell is concrete with part of the steel containment shell embedded in the concrete which the corium would have to dissolve/melt through both and then encounter a mass of thick concrete below the shell before it could find natural earth. Cracks in the concrete would not have been envisioned neither would the corium traveling somewhere it's not suppose to like the torus (wetwell). Still it would have a thick concrete foundation to dissolve and melt through but should cool down before that happens.

So, you need time, cooling and keep the corium in place until it cools down. Further contamination is a given, hopefully it can be just localized.

Aside:
Concrete consists mainly of small rocks (example 3/4" or 1") and sand with cement as the binder (glue) and its major usefulness in this case is a hardened thick mass but nothing magical even with embedded steel reinforcement or maybe some type of plating. As the cement itself hardens over its approximate 116 year lifetime (before becoming inert) it takes about 45 years for it (the cement) to become as hard as the natural rock it contains (now concrete is referred to as having a half life of 50 years or so depending on the mix design).

Isn't this true ONLY if fission doesn't restart? The high levels of Iodine-131 reported recently makes be strongly doubt that fission has not been ongoing, at least in Unit 2.

 

[Bioengineer01]

I have two questions/comments:

1. All the news stories about cooling the #2 SFP say that the point of this operation is to reduce the humidity inside the #2 building. Does anything establish that the humidity actually comes from the SFP? Presumably, there are holes in the containment vessel, and probably in the RPV, and steam is escaping. The steam can be seen in photos of the blow(n)-out panel in the east wall of unit #2. Can the high humidity result from the reactor steam instead of from the SFP steam?

2. A lot of Cs and Sr isotopes have already been washed out of the cores (and, for Cs, vaporized in the first couple of days). Over time, more will be washed out. If the core is molten and covered with a solid shell that is permeable is any way, and the core is immersed in flowing hot water, then almost all the soluble radioisotopes will eventually be washed out. I am pretty sure that the chemical forms of Cs and Sr that occur in corium are readily soluble in water (generally, these are oxides, which dissolve in water to make the corresponding hydroxides). This dissolution will have a very bad effect on the water collection and purification efforts. However, the loss of these materials from the corium should greatly reduce its heat-generating ability and its radioactivity. The fissionable materials should have already decayed (or mostly decayed?), and most of the heat produced now (and in the longer term) is from radioactive decay (unless I'm missing something). It seems to me that TEPCO could end up with very hot water (that Areva thinks they can cleanse and I think will mostly end up in the ocean) and not-that-hot cores that will actually solidify and not pose the type of explosion risk that some posts suggest.

Sounds correct to me, except that it is only true if critical level fission doesn't restart which is not supported by the little data we have from TEPCO about the Iodine-131/Cesium-137 ratio in the sea water inlet from the 27 or 28th of May reported the next day...

 

[Bioengineer01]

No, I don't think that it is from SFP, unit 2 SFP power is much smaller than in unit 4, and unit 4 wasnt generating steam always, also unit 2 SFP temperature was for example 45C but steam was still there, and unit 2 core and drywell are at atmospheric pressure, also on pne of movies when they zoom in into hole in wall we can see some debris and that steam is not only from left (sfp location) but also from center

For whatever is worth, I agree. Also close to Unit 2 sea water inlet is that TEPCO reported huge increases of the ratio of Iodine-131 to Cesium-137, suggesting re-criticality

 

[elektrownik]

Exposed workers, tepco news: http://www.tepco.co.jp/en/press/corp-com/release/11060311-e.html

 

[Bioengineer01]

One of the many things about the ongoing disasters in Japan is the almost complete lack of data about the most simple and easy to achieve measurements.

Like what is in the constant steam coming out of a reactor building. Or what's left of one. You would think there doesn't exist the technological ability to put sensors in the steam to measure the radioactivity and materials coming out a ruined reactor, or ruined fuel ponds.

That sort of information would seem important to my simple mind. Yet I have never, since day one, even heard of a discussion about it. (I may have missed it here of course).

It just seems (again, to my simple mind) that knowing what is coming out of steaming nuclear pile of rubble would be important. Especially to the people working nearby. But I imagine anyone downwind would also want to know.

Sometimes (usually at night) I see these huge steam clouds escaping into the air. We know it's from melted fuel rods, we know melted nuclear fuel rods are dangerous, so why no data on what is simply going into the air, 24/7?

Is that too much to ask?

No, it is a basic source of data that should be reported, same on the radioisotipic monitoring of the water in the basements of all the buildings with spectrums available for people to check and double check their measurements. Everytime they don't report something it has been because it is bad. You can verify this by just checking what happened with the variables that they stop reporting on when they are able to improve them and they start reporting on them again. One of those instances that I followed in detail was the temperature in RPV of Unit 3

 

[robinson]

I can get more info (or I could in March) about the various isotopes being released from the reactors from monitoring stations in California than ever came out of Japan.

 

[elektrownik]

new data: up to 30 may: http://www.cpdnp.jp/pdf/110603Takasaki_report_May30.pdf

 

[Bioengineer01]

Is this total dose so far? Expected total lifetime dose? Or what?

They are talking about internal contamination, so this will accumulate for their lifetimes if they can't remove the contaminants... It is not clear in the English article what type of dose they are talking about, I can't translate Japanes accurately enough to infer from the other article

 

[Bioengineer01]

Exposed workers, tepco news: http://www.tepco.co.jp/en/press/corp-com/release/11060311-e.html

From this article it would seem that they are talking about 50 year doses from the internal exposure. Most likely this will kill their thyroids rather than produce cancer...

 

[Bioengineer01]

new data: up to 30 may: http://www.cpdnp.jp/pdf/110603Takasaki_report_May30.pdf

Useful for Japanese readers only. Any translation around?

 

[GJBRKS]

A 5- shindo magnitude around Iwaki one hour ago ,

that's 40 km from Daiichi ?

http://translate.google.nl/translate?js=n&prev=_t&hl=nl&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fweather.goo.ne.jp%2Fearthquake%2F11060401000.html

 

[razzz]

Isn't this true ONLY if fission doesn't restart? The high levels of Iodine-131 reported recently makes be strongly doubt that fission has not been ongoing, at least in Unit 2.

This http://adultonsetatheist.blogspot.com/2011/03/corium.html" is as good as any. As long as overall heat output is trending down, it is the best you can hope for in this disaster. Might be some spikes along the way especially with Unit 3 and its MOX fuel but what can you do except wait it out?

As far as ground water contamination, they will just have to pump and flush it to the sea unless they want the entire site to become unworkable with standing-saturated-radioactive-contaminated-water.

 

[tsutsuji]

For people interested in cracks created by earthquakes on nuclear power plants, here is a report published in November 2010 about the cracks caused by the 2007 earthquake at the Kashiwazaki-Kariwa nuclear power plant unit 3 : http://www.tepco.co.jp/nu/material/files/k10111501.pdf (page 17 shows a crack in the reactor building, page 19 in the turbine building).

A 5- shindo magnitude around Iwaki one hour ago ,

that's 40 km from Daiichi ?

http://translate.google.nl/translate?js=n&prev=_t&hl=nl&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fweather.goo.ne.jp%2Fearthquake%2F11060401000.html

A map of intensities in Fukushima prefecture is shown on the following video : http://www.mbs.jp/news/jnn_4742288_zen.shtml . A tsunami is ruled out.

Tepco says the radiation data measured at monitoring posts after this quake at Fukushima Daiichi and Daini are OK : http://www.asahi.com/national/update/0604/TKY201106030652.html

 

[Bodge]

Tellurium-132 was detected 6 km northwest of Fukushima I Nuke Plant in Namie-machi in the morning of March 12.

http://www.yomiuri.co.jp/feature/20110316-866921/news/20110603-OYT1T01065.htm

"It was disclosed that the radionuclide that would indicate the nuclear fuel temperature exceeded 1,000 degrees Celsius was detected in the morning of March 12 in Namie-machi in Fukushima Prefecture, about 6 kilometers [north] from Fukushima I Nuclear Power Plant."

According to ex-SKF, before venting and before any explosions.

The timeline of what went on is far from complete.

 

[Bodge]

There have been some extensive steam/smoke displays at Units 3 and 4 today.

Releases from 3 and 4 seem to coincide with one another.

Since TEPCO's official explanation for the hydrogen explosions in Unit 4 claim that hydrogen entered the building from a connection to Unit 3,

Could Unit 3 be venting smoke and steam via unit 4 to this day?

 

[razzz]

There have been some extensive steam/smoke displays at Units 3 and 4 today.

Releases from 3 and 4 seem to coincide with one another.

Since TEPCO's official explanation for the hydrogen explosions in Unit 4 claim that hydrogen entered the building from a connection to Unit 3,

Could Unit 3 be venting smoke and steam via unit 4 to this day?

IMO, there is no containment for reactors 1,2 and 3 all are open to the surrounding environment. If radioactive contamination doesn't vent/steam/vaporize away it gets washed away with cooling water. Cooling water at best is 'stored' and storage is beginning to exceed limits or capacity. This, besides leakage and ground water infiltration.

 

[Bioengineer01]

This http://adultonsetatheist.blogspot.com/2011/03/corium.html" is as good as any. As long as overall heat output is trending down, it is the best you can hope for in this disaster. Might be some spikes along the way especially with Unit 3 and its MOX fuel but what can you do except wait it out?.

Yes, just wanted to point out that things are much more complicated that what some posts make them appear to be...

Can anybody estimate what could happen if there is a hydrogen explosion around the corium creating a compression wave while fission is ongoing? I am not an expert, but when I thought about the scenario got scared and decided to post it here, where somebody may know the answer...

 

[etudiant]

Tellurium-132 was detected 6 km northwest of Fukushima I Nuke Plant in Namie-machi in the morning of March 12.

http://www.yomiuri.co.jp/feature/20110316-866921/news/20110603-OYT1T01065.htm

"It was disclosed that the radionuclide that would indicate the nuclear fuel temperature exceeded 1,000 degrees Celsius was detected in the morning of March 12 in Namie-machi in Fukushima Prefecture, about 6 kilometers [north] from Fukushima I Nuclear Power Plant."

According to ex-SKF, before venting and before any explosions.

The timeline of what went on is far from complete.

Is this not a smoking gun indication of structural damage to the reactor(s) from the quake, prior to the added impact of any explosions?

 

[robinson]

Technical question. Does anyone know the form of Cesium that is produced by a nuclear reactor? Is it pure cesium? Or an oxide?

In short, is the Cesium-137 produced a pure metal? Or is it oxidized inside the fuel rod? If it is oxidized, where does the oxygen come from?

 

[robinson]

Is this not a smoking gun indication of structural damage to the reactor(s) from the quake, prior to the added impact of any explosions?

I thought it was now common knowledge that all three reactors melted down before the explosions. That in fact the explosions were the result of catastrophic failure of the reactors.

Isn't that the latest version of what happened?

 

[elektrownik]

Is this not a smoking gun indication of structural damage to the reactor(s) from the quake, prior to the added impact of any explosions?

There was (a long time ago in march) interview with tepco worker which told that after earthquake there was explosive sound, dark smoke in unit 3 and it was hard to breathe

 

[SteveElbows]

Once core melting was underway I don't know if additional earthquake damage is necessary in order to explain radioactive releases into the environment.

Certainly it should not be news that radiation levels started to rise well before the explosion, since early data from site shows that readings started to go up considerably at some point shortly after 4am on the 12th and with quite a leap starting by 10.20am.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110528e14.pdf

 

[etudiant]

Technical question. Does anyone know the form of Cesium that is produced by a nuclear reactor? Is it pure cesium? Or an oxide?

In short, is the Cesium-137 produced a pure metal? Or is it oxidized inside the fuel rod? If it is oxidized, where does the oxygen come from?

cesium is an alkaline metal and will react powerfully with water to form an hydroxide. The presence of iodine will cause cesium iodide to form in preference to the hydroxide, but cesium iodide also dissolves very well in water.
The cesium fission product is in metal form afaik in the fuel tubes, as long as the tube remains intact.
When the zirconium is destroyed because of the loss of coolant, the cesium metal boils out of the hot fuel assemblies. The cesium vapor will deposit all over, on pretty much every surface that is cold enough, so it is a serious contaminant, not easily flushed because it is so reactive.
Afaik, the Japanese helicopters that did the water drops early in the crisis were very badly contaminated and their cleanup required special equipment provided by the US military, because the conventional cleanings failed to dislodge the cesium embedded in the helicopters paint.

 

[etudiant]

Once core melting was underway I don't know if additional earthquake damage is necessary in order to explain radioactive releases into the environment.

Certainly it should not be news that radiation levels started to rise well before the explosion, since early data from site shows that readings started to go up considerably at some point shortly after 4am on the 12th and with quite a leap starting by 10.20am.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110528e14.pdf

The reactors had clearly failed by the morning of Mar 12. However, the venting had not yet started, at least afaik, when these measurements were made 6 km away. That would seem to show an earthquake generated leak in the containment, which is something that was unclear previously.

 

[Borek]

The cesium fission product is in metal form afaik in the fuel tubes, as long as the tube remains intact.

I strongly doubt that. Cesium is created in the form of just nucleus, ejected during fission. It grabs any electrons it can from the surroundings. I doubt it gets more electrons than needed to become Cs⁺. Counterions are whatever happened to be in the vicinity and was not keeping its electrons strong enough.

 

[etudiant]

I strongly doubt that. Cesium is created in the form of just nucleus, ejected during fission. It grabs any electrons it can from the surroundings. I doubt it gets more electrons than needed to become Cs⁺. Counterions are whatever happened to be in the vicinity and was not keeping its electrons strong enough.

Thank you for the extra information. I had not known the sequence of how one gets from a fission fragment to
a fission product. So cesium metal never forms even if the intact fuel.
Must be a real nuclear dance inside the fuel rods, with highly charged fission fragments competing for available counterions.

 

[radio_guy]

cesium is an alkaline metal and will react powerfully with water to form an hydroxide. The presence of iodine will cause cesium iodide to form in preference to the hydroxide, but cesium iodide also dissolves very well in water.
The cesium fission product is in metal form afaik in the fuel tubes, as long as the tube remains intact.
When the zirconium is destroyed because of the loss of coolant, the cesium metal boils out of the hot fuel assemblies. The cesium vapor will deposit all over, on pretty much every surface that is cold enough, so it is a serious contaminant, not easily flushed because it is so reactive.
Afaik, the Japanese helicopters that did the water drops early in the crisis were very badly contaminated and their cleanup required special equipment provided by the US military, because the conventional cleanings failed to dislodge the cesium embedded in the helicopters paint.

some light reading, just to clarify all thjs.


http://www.epa.gov/radiation/radionuclides/cesium.html
http://en.wikipedia.org/wiki/Caesium

 

[SteveElbows]

The reactors had clearly failed by the morning of Mar 12. However, the venting had not yet started, at least afaik, when these measurements were made 6 km away. That would seem to show an earthquake generated leak in the containment, which is something that was unclear previously.

I still don't see why this means it has to be earthquake generated. Surely the state of the reactor due to core melting is enough to cause problems by this stage.

There are not a huge number of pressure readings from the early hours of the situation at the reactors, but there are some. Reactor 1 seems most interesting of the 3 during the early hours of the 12th. At some point the reactor pressure goes from 6.9 MPa at 20:07 on the 11th to 0.8 Mpa by 02:45 on the 12th. Drywell is 0.6 MPa at 01:05 on the 12th, 0.84 Mpa at 02:30, 0.78 by 04:19, then tends to fluctuate around 0.74 and 0.75 until its time for steeper declines in the afternoon.

In my mind this means I can construct alternatives to earthquake damage to explain releases in this period. Extreme pressure or temperatures may have caused certain small drywell failures at reactor 1 by around 4am on the 12th.

 

[etudiant]

I still don't see why this means it has to be earthquake generated. Surely the state of the reactor due to core melting is enough to cause problems by this stage.

There are not a huge number of pressure readings from the early hours of the situation at the reactors, but there are some. Reactor 1 seems most interesting of the 3 during the early hours of the 12th. At some point the reactor pressure goes from 6.9 MPa at 20:07 on the 11th to 0.8 Mpa by 02:45 on the 12th. Drywell is 0.6 MPa at 01:05 on the 12th, 0.84 Mpa at 02:30, 0.78 by 04:19, then tends to fluctuate around 0.74 and 0.75 until its time for steeper declines in the afternoon.

In my mind this means I can construct alternatives to earthquake damage to explain releases in this period. Extreme pressure or temperatures may have caused certain small drywell failures at reactor 1 by around 4am on the 12th.

Thank you, that is most helpful data. The sharp loss of pressure in reactor 1 before 2.45 am on Mar 12 would fit nicely with the timeline recording reactor products 6 km away a few hours later.
As you point out, the leak does not appear to be directly from the quake, but rather a subsequent pressure generated failure. Still, it indicates that the integrity of the facility was materially compromised even before the explosions.

 

[MiceAndMen]

Congratulations to the people at the sharp end of this situation.

It may only be a small solution in a mass of big problems, but the establishment of closed loop cooling for the SFP in Unit 2 is a turning point I think and it gives me a sense of optimisim that we will have improved success in working our way through this.

No more radiation washed out or steamed off of at least part of the site.

Good news.

Credit where credit is due, I agree. Of course they would be worthy of much more credit if they had started doing this weeks ago. They've allowed things to get worse by delaying prompt action, and that nullifies whatever praise they're otherwise deserving of this week. But it is a step in the right direction.

 

[etudiant]

Credit where credit is due, I agree. Of course they would be worthy of much more credit if they had started doing this weeks ago. They've allowed things to get worse by delaying prompt action, and that nullifies whatever praise they're otherwise deserving of this week. But it is a step in the right direction.

Is this actually the case?
My impression, from looking at the stuff that is getting deployed, is that we are seeing a lot of custom built gear, rather than a lot of off the shelf equipment. It is pretty impressive, to conjure this up in a couple of months. At a minimum, it proves that the TEPCO road map did actually reflect some serious engineering effort.
Maybe it has been ' a day late and a dollar short', but there is a real effort.

Short of making this a global effort, it is hard to see what TEPCO could have done additional.
Presumably, the global effort option was rejected both for operational as well as political reasons, ie how do you coordinate a nuclear emergency with a polyglot crew that cannot talk to each other?.

 

[SteveElbows]

Thank you, that is most helpful data. The sharp loss of pressure in reactor 1 before 2.45 am on Mar 12 would fit nicely with the timeline recording reactor products 6 km away a few hours later.
As you point out, the leak does not appear to be directly from the quake, but rather a subsequent pressure generated failure. Still, it indicates that the integrity of the facility was materially compromised even before the explosions.

I forgot to include TEPCOs own thoughts on containment damage which came out in the 2nd half of may as part of a very long Japanese report that had not been fully translated into english last time we talked about it, and I presume it still hasnt. But there were some press stories about it which we talked about here, and I computer-translated a few paragraphs that were related to the timing of containment failures.

Their assumptions, which were apparently based on things such as pressure readings, don't exactly match what I've been saying, although they are not too far off for some reactors.

For reactor 1 they estimated a leak equivalent to a 3cm hole in drywell 18 hours after quake. Worsening to 7cm by 50 hours after quake. So here they are already admitting to some containment damage by the morning of 12th, although some 4 hours later than I guestimated based on a few pressure readings.

For reactor 2 they estimated a leak equivalent to a 10cm hole in drywell 21 hours after quake. Suppression chamber damage obviously followed at a later date, when the 'strange sound was heard. Drywell damage at 21 hours after quake is late on morning of 12th, a bit too late to blame this for the data 6km away.

I suppose it is possible that these '18 hours' and '21 hours' estimates that TEPCO mentioned are not supposed to be the exact starting times for containment failure, but rather an indication of how bad the damage may be at that moment. eg if damage equivalent to 3cm at around 8:30, maybe there could have been damage equivalent to 1cm at 5am. I cannot tell until I see full translation, and even then I would not be surprised if this remains a little unclear. Its not as if when I study what pressure data is available to us, the times TEPCO said fit perfectly with a dramatic event shown in data at precisely these times.

Anyway TEPCOs analysis of reactor 3 may be of particular interest to those seeking possible earthquake damage, because as discussed when press articles appeared on this subject some days ago, TEPCO seem to be suggesting that some piping system may have been damaged at reactor 3 by the earthquake itself. Again I wait in hope of full document translation, and I have no idea whether such early damage may be responsible for any of the radiation being picked up on morning of march 12th.

 

[~kujala~]

I updated my https://www.physicsforums.com/showpost.php?p=3270265&postcount=5081" with some new references and ideas. First it looked like a simple case, then it got complicated. Even now there are many explanations and possibilities. Nothing new from TEPCO for a long time...

It's so long, I made it directly as HTML:
http://varasto.kerrostalo.huone.net/unit4_theory.html

 

[hbjon]

I strongly doubt that. Cesium is created in the form of just nucleus, ejected during fission. It grabs any electrons it can from the surroundings. I doubt it gets more electrons than needed to become Cs⁺. Counterions are whatever happened to be in the vicinity and was not keeping its electrons strong enough.

I would like to see the math on how Cs is created in a fuel rod. Exactly how long does it take for a fresh fuel rod to produce a gram of the stuff. Since U238 and U235 have approximately that number of electrons AFAIK, doesn't Cs take its share of them after the products decay? Btw, I am not an expert on the chemical properties of isotopes or nuclear physics. I guess I am just an annoying "backseat driver". <-----My disclaimer

 

[SteveElbows]

Thank you, that is most helpful data. The sharp loss of pressure in reactor 1 before 2.45 am on Mar 12 would fit nicely with the timeline recording reactor products 6 km away a few hours later.

I should also point out that I am not sure that particular pressure drop, of the reactor itself, gives a proper indication of release of radioactive substances to outside world. I am not especially knowledgeable about this stuff, but I assumed that drop of reactor pressure vessel tells us that stuff has gone from pressure vessel to containment vessel. It sets the situation up for trouble, but its a drop in containment pressure that we should look for when thinking about when exactly this material escapes into the wider world. So for my crude estimations of radioactive release timing I was looking for even slight falls in containment pressure.

 

[SteveElbows]

There is another piece of data from early on March 12th which demonstrates radioactive release. It is mentioned in TEPCO document that analyses situation at plant in first hours. In the reactor 3 status table at the very end of the document, in the final row about emissions, it says:

Exhaust stack radioactive monitor : noise was confirmed after reactor scram, but it was stable rate until termination of recording From around 5:00 on March 12th, it showed temporarily gradual increase. Since it is assumable that the water level of the reactor of Unit 3 at that time was above flooded level to cover the fuel, increase in dose is effected by the other units at the site.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110524e13.pdf

 

[Borek]

Since U238 and U235 have approximately that number of electrons AFAIK, doesn't Cs take its share of them after the products decay?

Number of electrons in uranium atom is exactly the same as number of electrons needed for fissions products. Trick is, when fission products run apart they do it very fast. They can be able to take some of the electrons from the original uranium atom with them, I am not sure about details, but basically these are two massive, highly charged ions going through the fuel rod and ionizing everything on their way. Electrons don't need much time to get back "in place", but it is a messy process. Final products (in chemical sense) are ions - like Cs⁺ and I^-, but they are put in random places in the original lattice of uranium oxide, creating local defects, so they can be hardly described as specific compounds.

 

[LabratSR]

More storage capacity to be brought on site.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110603_02-e.pdf

 

[etudiant]

More storage capacity to be brought on site.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110603_02-e.pdf

Hope that these are just the specs for the product, because they need at least two of each of those every day
just to hold the injected water at the current rate.
TEPCO is reportedly putting in a 100,000 ton storage tank underground, but it will not be ready until August.
Provided the AREVA treatment plant starts operating by mid June as expected, TEPCO might have just enough capacity to avoid an overflow of highly contaminated water. It does not look however as though they will be able to store the treated water unless there is some tanker storage planned. So there will of necessity be a further ocean disposal of contaminated water.

 

[Astronuc]

I would like to see the math on how Cs is created in a fuel rod. Exactly how long does it take for a fresh fuel rod to produce a gram of the stuff. Since U238 and U235 have approximately that number of electrons AFAIK, doesn't Cs take its share of them after the products decay? Btw, I am not an expert on the chemical properties of isotopes or nuclear physics. I guess I am just an annoying "backseat driver". <-----My disclaimer

By successive beta decay, Te -> I -> Xe -> Cs -> Ba -> La (all having the same A, but different Z. Some Cs is born as a fission product. Te, I, Xe are also born as fission products, and decay by beta emission as shown.

Number of electrons in uranium atom is exactly the same as number of electrons needed for fissions products. Trick is, when fission products run apart they do it very fast. They can be able to take some of the electrons from the original uranium atom with them, I am not sure about details, but basically these are two massive, highly charged ions going through the fuel rod and ionizing everything on their way. Electrons don't need much time to get back "in place", but it is a messy process. Final products (in chemical sense) are ions - like Cs⁺ and I^-, but they are put in random places in the original lattice of uranium oxide, creating local defects, so they can be hardly described as specific compounds.

The fission products do not go far - only a few microns (2-6 um) with the heavier nuclide going shorter distances, and the lighter one going longer. The Te - Cs are the heavier ones, and Se->Br->Kr->Rb->Sr->Y are the lighter ones.

Edit/update: The grains in the polycrystalline UO₂ ceramic are on the order of 10 microns, and actually 2 to 20 microns. At temperature, the smallest grains basically reform as part of larger grains (the atoms at the grain boundaries migrate from small grains to large grains).

 

[jlduh]

I thought it was now common knowledge that all three reactors melted down before the explosions. That in fact the explosions were the result of catastrophic failure of the reactors.

Isn't that the latest version of what happened?

It seems that the three cores melted quickly, agree. But The containment was not supposed to leak in the morning of March 12. So how did this Tellurium go out of the cores, out of the RPV, out of the containment, to deposit 6 kms away from Daichi?

Did they already vent? Tepco said no (as a matter of fact Kan was visiting the plant that morning and was upset that no venting had been done despite official governement approval). So how did this Tellurium come out?

Either Tepco already vented, or the containment was already breached, the earthquake being possibly the only credible explanation to explain some leak in the containment...

 

[LabratSR]

Hope that these are just the specs for the product, because they need at least two of each of those every day
just to hold the injected water at the current rate.
TEPCO is reportedly putting in a 100,000 ton storage tank underground, but it will not be ready until August.
Provided the AREVA treatment plant starts operating by mid June as expected, TEPCO might have just enough capacity to avoid an overflow of highly contaminated water. It does not look however as though they will be able to store the treated water unless there is some tanker storage planned. So there will of necessity be a further ocean disposal of contaminated water.

If I read it right under "Transportation Duration" they are planning on delivering up to 6 a day of the bigger ones for a month and 4 a day of the smaller ones for 2 months.

 

[jlduh]

Hope that these are just the specs for the product, because they need at least two of each of those every day
just to hold the injected water at the current rate.
TEPCO is reportedly putting in a 100,000 ton storage tank underground, but it will not be ready until August.
Provided the AREVA treatment plant starts operating by mid June as expected, TEPCO might have just enough capacity to avoid an overflow of highly contaminated water. It does not look however as though they will be able to store the treated water unless there is some tanker storage planned. So there will of necessity be a further ocean disposal of contaminated water.

Hummm, 100 000 tons underground storage installed in August? Do you have a idea of how big this is? How can they dig a hole that big and install a tank that big in so little time? That's putting below the ground a tanker, not exactly an easy task! And where?

I don't understand this statement.

 

[etudiant]

Hummm, 100 000 tons underground storage installed in August? Do you have a idea of how big this is? How can they dig a hole that big and install a tank that big in so little time? That's putting below the ground a tanker, not exactly an easy task! And where?

I don't understand this statement.

World Nuclear News here
http://www.world-nuclear-news.org/RS_cooling_success_while_water_builds_up_0306111.html
notes that TEPCO is moving to install 3 tanks on the site, a 10,000 ton unit for highly contaminated water, a 19,400 ton one for mid level contaminated water and a 140,000 ton low level contaminated water tank. No completion dates are given and no construction details.

 

[hbjon]

That explanation makes me think there is a complex stew of isotopes unwinding towards the zone of stability, decaying at various halflives, and converting mass to energy in the process. One thing that I cannot get my mind around is when you say "Te, I, and Xe are born by fission." Would that be U235 or P239?