Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[wasteinc]

A colleague indicated it was apparently unintended for the hydrogen and steam from containment to be vented into the secondary or upper containment (metal structure). He indicated that duct work to carry to the appropriate stack had ruptured, and the hydrogen leaked into the upper containment area. As far as I know, one would not design a system to vent H₂ into the upper containment, precisely in order to prevent what did happen.

Salty seawater, which I expect has a fairly good soluble oxygen content, is problematic because it corrodes SS304. I imagine the intrusion produced a crud burst - crud being oxides of Fe, Cr, Ni, etc, and that could deposit on the fuel as it boils dry. Any crud on the fuel would be transportable in the seawater, which would explain the increase in Co-58,60 activity.

I'm curious about the behavior of UO₂ oxidation in seawater. I'm not aware of any studies.

I second that

TEPCO want us to believe it has some kind of control over the situation. So that was about all the narrative that they vented the H2 to the upper part in order to relieve pressure. Which is probably ********. The "venting" according to those guys http://www.ustream.tv/recorded/13410573" was the result of the extreme 8bar pressure inside the containment vessel, that made the lid of the containment vessel to give and relieve the pressure exactly as the lid of a cooker would have made. (we are talking about the second containment vessel).

As far as their presentation goes, the venting from the pressure cooker (containment 1), is done inside the containment 2 as long as the pressure goes over a certain point (if I remember they said it was around 80-88bar). There the radioactive steam cools down and becomes water again in the torus relieving pressure. In their explanation there was no way you could "vent by design" the second containment.

probably they had the explosions and then baptised them controlled releases to save face.

and thank all of you for the invaluable info and insights we get

 

[83729780]

is there any explanation for the temperature rising in the Common Use Spent Fuel Pool (the big one)?

status after 23/03:

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the temperature on 23 March was reported to be 57 °C.

http://www.iaea.org/newscenter/news/2011/fukushima240311.html

status on 24/03:

At the Common Spent Fuel, the power supply was restored as of 24 March, 06:37 UTC and cooling started again 28 minutes later. Work is now under way for the recovery of the lighting and instrumentation systems. As of 24 March, 09:40 UTC, the water temperature of the pool was around 73 °C.

http://www.iaea.org/newscenter/news/tsunamiupdate01.html

 

[|Fred]

According to the Japanese authority (NISA) , taking into consideration the result of there analysis of that water that they found in the turbine building , it is very likely that it comes from the reactor core, although they can not exclude that is might come from the SFR.

They were not able to determine how the water came there.. Radiation mesure fo the water is 3.9×10^6 Bq/cm^3 (unit 3)

on the 25 At 3.10 am JST Unit 1 reactor containment vessel pressure went up to 6 atm (source NHK Japan)

[PLAIN]http://k.min.us/im0bGQ.jpg

 

[Lefteris]

Hello all, I am a graduate student of the University of Tokyo, from Greece and am currently living in Tokyo. I am studying precision engineering there (electronics/robotics). I have to admit I am overwhelmed by the things I hear both from the news and from various websites.

We were told that tap water has become unfit for infants 2 days ago with a level of 210 Bq/l but today the warning was lifted with a reported level of 79 Bq/l. Meanwhile I am watching the environmental radiation levels from my university's page http://www2.u-tokyo.ac.jp/erc/index_e.html" and I see elevated values, especially at the campus my lab is located at, Kashiwa campus.

I am not a physicist and I don't understand these values. I would like to ask the people here if they know what kind of values would be safe .. and what would prolonged exposure to values such as this (assuming I go to my lab daily) would mean?

Moreover about these radioactive substances such as iodine and caesium that have been detected. I heard that caesium has a half-life of 30 years. Doesn't that make it the most dangerous substance released, since it would mean that the contamination will stay in the environment for generations?

Sorry for the number of dizzying questions, but as with most people here in Tokyo we are trying to understand what to do with this situation. And going back home is a very hard option since all our lives/careers are here.

Thanks in advance!

 

[AntonL]

I would guess that most of the water is still from the Tsunami, contaminated later.

Good point -- yes, there was that source of water, also. ()

http://www.spiegel.de/panorama/0,1518,753058,00.html]Die[/PLAIN] Männer hatten am Donnerstag I am Untergeschoss eines Turbinengebäudes von Block 3 gearbeitet. Nachdem dort am Vortag weder Wasser noch erhöhte Strahlung festgestellt worden war, hatten sie bei ihren Arbeiten keine Schutzstiefel an - das radioaktiv belastete Wasser lief ihnen in die Schuhe.

translated means:
The men had worked on Thursday in the basement of a turbine building block 3. As on the previous day no water or increased radiation had been found, they did not wear protection boots - the radioactively contaminated water ran into into their shoes.

30cm water in basement is a huge quantity, possibly they stepped into a cable trench that was not pumped dry and accumulated contaminated water.

 

[Borek]

I am not a physicist and I don't understand these values. I would like to ask the people here if they know what kind of values would be safe .. and what would prolonged exposure to values such as this (assuming I go to my lab daily) would mean?

Compare these values with http://xkcd.com/radiation/

And read footnotes on the university page - they say what values are considered to be safe/normal. Note that in many places in he world natural levels of radiation are much higher, yet people living there have no traces of radiation related diseases. See http://en.wikipedia.org/wiki/Natural_background_radiation

 

[jensjakob]

http://www3.nhk.or.jp/daily/english/25_19.html

Propably damaged #3 RV :-(

 

[artax]

Joe NEUBARTH: i asked several times here if we were talking about relative pressures or absolute pressures and got no answer. On the METI doc that you link, i think you'll find an answer if you go down a little bit, to the line "D/W design service pressure". You will read a first pressure number and then the second is defined as "abs" -absolute. So all the numbers you have in this report otherwise specified are relative pressure i think, which explain why it can be negative.

But, it means that on reactors 2 and 3, those pressures are below atmospheric pressure, which is kind of strange and... scary?

Again, it's very difficult to draw a conclusion based on some numbers but to me this could (i say could) mean that the 2 and 3 reactors are dead from their confinement standpoint... and that N°1 is still rising...

All three reactors had explosions, n°1 seemed to bit quite "clean" (outer walls). N°2 had an explosion that nobody saw, it has been said that it was in the suppression pool and that it was leaking. N°3 had 3 simultaneous big explosions (the most impressive) and some here expressed concerns about it's current state.

Concerning the explanation given of why venting in the building instead of outside: ok that's what i heard BUT would you do it deliberately a second time (N°3) after having experienced the first time an explosion in the building (where the pools are!) because of H2 presence? Notice that venting in a room that explodes ends up with everything in the atmosphere + a severe explosion... That's a strange thing.

Like you I was confused by the pressure data, but one RV was stated as having 0MPa which I assume means atmospheric. As absolute 0MPa is rather difficult to achieve! And any negatives must be relative to atmosphere, but then again they seem to be very inconsistent with their use of units and change from millisieverts to micro, and then chuck in per hour when it suits them!

 

[jensjakob]

Pressure - interesting to see on #1 that the pressure is allmost identical between RV, drywell and Torus. And that the radiation is also allmost identical.

 

[DrDu]

Moreover about these radioactive substances such as iodine and caesium that have been detected. I heard that caesium has a half-life of 30 years. Doesn't that make it the most dangerous substance released, since it would mean that the contamination will stay in the environment for generations?

Caesium is very soluble so that it gets washed away quickly. It also has a short biological half live time, i. e. it leaves the body within several hundred days after incorporation.
Incorporating 80000 Bq of Caesium results in a body dose of 1 mSv.
Caesium gets stored especially in mushrooms and in the soil of forests for a long time.
So you should reduce your dayly intake of local Matsutake mushrooms if you could afford them at all :-)
Increased levels of iodine are potentially more worrysome as iodine accumulates in the tyroid gland and there are clear indications of induction of cancer by irradiation of the tyroid in epidemiologic studies.

 

[artax]

Hello all, I am a graduate student of the University of Tokyo, from Greece and am currently living in Tokyo. I am studying precision engineering there (electronics/robotics). I have to admit I am overwhelmed by the things I hear both from the news and from various websites.

We were told that tap water has become unfit for infants 2 days ago with a level of 210 Bq/l but today the warning was lifted with a reported level of 79 Bq/l. Meanwhile I am watching the environmental radiation levels from my university's page http://www2.u-tokyo.ac.jp/erc/index_e.html" and I see elevated values, especially at the campus my lab is located at, Kashiwa campus.

I am not a physicist and I don't understand these values. I would like to ask the people here if they know what kind of values would be safe .. and what would prolonged exposure to values such as this (assuming I go to my lab daily) would mean?

Moreover about these radioactive substances such as iodine and caesium that have been detected. I heard that caesium has a half-life of 30 years. Doesn't that make it the most dangerous substance released, since it would mean that the contamination will stay in the environment for generations?

Sorry for the number of dizzying questions, but as with most people here in Tokyo we are trying to understand what to do with this situation. And going back home is a very hard option since all our lives/careers are here.

Thanks in advance!

Studied some nuclear chemistry at uni a long time ago hence my interest but I would have to research those isotopes.
However the news here did mention that the ALLOWED UK levels for infants in tap water used for drinking (making up milk) are 5 TIMES HIGHER than those allowed in Japan... so I wouldn't worry at all.
The main reason Iodine is important is because the body has some in it always (thyroid gland) and can't tell the difference between the active isotopes and the natural ones. So if you take the Iodide pills, the iodide atoms (ions) just displace the radio ones very quickly before they've been their long enough to have any effect.
I'm pretty sure the authorities are tellining the truth about the tap water, and washing with it will be no problem at all... and drinking!
If I was in Japan now, I would just avoid the exclusion zone and don't go swimming in the sea!

 

[|Fred]

New video material has been released to the public including close up on the roof of unit 3, 4, 2 and 1

I estimate that the footage give some evidences that the debris that we though were rod are not.

 

[jensjakob]

New video material has been released to the public including close up on the roof of unit 3, 4, 2 and 1

I estimate that the footage give some evidences that the debris that we though were rod are not.

Link?

 

[dave2004]

I found this forum searching for discussions about facts of what is happening in Japan, and have been reading it for nearly a week now. I am glad to see so many people interested in what actually is happening instead of the scare mongering done by the media...

I wanted to add a perspective on the max. levels in food/water I found:
1) German newspaper:
some hot springs have up to 2700 Becquerel, in Germany baby food is allowed up to 370 and the EU proposes a limit of 500 to 1000 for drinking water in case of a nuclear accident (why only in case of an accident? don't ask me)
2) French government:
they seem to be based on a calculated yearly dose of 0.1 microSv of water contributing to the total yearly dose.

sources:
http://www.tagesspiegel.de/weltspiegel/wie-die-havarie-das-leben-veraendert/3982686.html

"Ein noch verträglicher Wert für Strahlenbelastung sei 300 Becquerel. Und „einige heiße Quellen in Kurbädern haben bis zu 2700 Becquerel.“ Das trinke dann natürlich niemand, aber trotzdem werden Werte eben gesetzt, willkürlich. Die Becquerel-Grenzen für Säuglingsnahrung in Deutschland liegt bei 370, die EU schlägt I am Falle eines Reaktorunglücks für Trinkwasser Grenzwerte von 500 bis 1000 Becquerel vor. "

and
http://www.sante.gouv.fr/IMG/pdf/bil0809-2.pdf
page 3:
Dose Totale indicative (DTI) 0,1 mSv/an

 

[jlduh]

Hi all,

i think that the news at not very good this morning from this damned plant.

Here in France some big newspaper like Le Monde (one of the main newspaper) are finally now step by step going towards the idea that the reactor (REACTOR) vessel of N°3 "could be damaged"...

http://www.lemonde.fr/asie-pacifiqu...-radioactifs_1498180_3216.html#ens_id=1493258

For me, with the last elements compiled here (especially the water on the basement 10 000 times more contaminated than in a normal functionning, but also the presence of strange elements that shoudn't be outside but ARE outside, ...) i have no more doubts about this fact: the reactor core has exploded the 14th of March, period.

And i think a lot of things that have been told (the controlled releases, the containment intact, the fact that it's no way like Tchernobyl, ...) has been a kind of cover up of the real situation, and this is really a problem when you think that offcially, people between 20 and 30 kms are still adviced to stay confined in their homes as i didn't see new info on that. I sincerely consider that it has everything to become worse than Tchernobyl :

-because the potential source is much bigger -we're talking about a complete plant with multi reactors and pools and not a single reactor, with all the domino effects we can anticipate - the number of dominos involved can be adjusted to your mood, more or less optimistic.

-because the density of population is terribly high in Japan

-because of the presence of the ocean which is already contaminated by the rejects of the cooling, and very quicky of all the **** which will be drained from the plant

In the article of Le Monde, it is reported that TEPCO is saying that bringing back the "normal" (what does it mean really as the situation is clearly more and more abnormal) cooling system "will last maybe more than one month, who knows?" ("Cela pourrait prendre encore plus d'un mois, qui sait"). If this sentence has been correctly reported, it shows that they are submerged by much more than a tsunami i think.

Bodge, i didn't react but the measurements you indicated are really bad of course and confirm that the contamination is not just from "controled releases" (which i doubted of very few days after the the start of the accident, the explosion of n°3 was the key moment for me). I personnaly suspect that a big part of the explosion could be from the suppression chamber based on the images i analysed, but we'll see.Now, we now that there is a fair amount of water at the basement and we will fairly quick hear about the word Corium to my opinion. The engineer from the CNIC conference (on USTREAM) in the video i posted and that has been reposted here a few hours ago (he has worked on the design of reactor N°4, his name is TANAKA) was saying in this video that one of the big problems with this design (relatively small containment chamber with the use of suppression chamber which is essentielly a big pool) implies a very high quantity of water below or near the core... which is not the safest idea in case of a fusion of the core. That's the next big question in the domino game: will corium meet water and have a big and violent love affair?

Before the TMI accident, almost nobody in the nuclear industry was seriously considering the practical possibility of a complete meltdown of the core. That's also why the TMI has been a so big surprise historically for the nuclear industry (50% of the core discovered melted when opened 5 years later). This design of BWR Mark I is from the mid sixties, so nothing has been anticipated for this scenario of core meltdown. This is no good news.

To the student in Japan who posted on this thread, i would just say that i don't know (personally) of any career more important than health and life for you and your family and friends. That's easier to say that from a place 17 000 kms away from Japan (less on the other side but I'm counting distances related to atmospheric movements in the last days) , for sure. But it is still true. Then, you have to make your own assesment of the situation there, and of the way it develops in the next days/weeks/months. But clearly, the situation at the plant is not good. Really not good. A few days after the start of the crisis, i adviced a friend (french) who was working in Tokyo to leave as quickly as possible when it was possible. But maybe I was too pessimistic of course (i would prefer to be pessimistic in fact, instead of realistic sometimes)...

 

[|Fred]

@Jakob HD NHK Japan..
this is the best I could find online but the quality of the feed is bad http://www3.nhk.or.jp/news/genpatsu-fukushima/movie/chapter_42.html .

 

[intric8]

Hello all, I am a graduate student of the University of Tokyo, from Greece and am currently living in Tokyo. I am studying precision engineering there (electronics/robotics). I have to admit I am overwhelmed by the things I hear both from the news and from various websites.

We were told that tap water has become unfit for infants 2 days ago with a level of 210 Bq/l but today the warning was lifted with a reported level of 79 Bq/l. Meanwhile I am watching the environmental radiation levels from my university's page http://www2.u-tokyo.ac.jp/erc/index_e.html and I see elevated values, especially at the campus my lab is located at, Kashiwa campus.

I am not a physicist and I don't understand these values. I would like to ask the people here if they know what kind of values would be safe .. and what would prolonged exposure to values such as this (assuming I go to my lab daily) would mean?

Moreover about these radioactive substances such as iodine and caesium that have been detected. I heard that caesium has a half-life of 30 years. Doesn't that make it the most dangerous substance released, since it would mean that the contamination will stay in the environment for generations?

Sorry for the number of dizzying questions, but as with most people here in Tokyo we are trying to understand what to do with this situation. And going back home is a very hard option since all our lives/careers are here.

Thanks in advance!

____________

I131 contribution 4.6483 microsieverts/day, based on 2 litres a day consumption. Reports are tap water levels dropping to 70 becquerel/kg as of today

http://falloutphilippines.blogspot.com/2011/03/current-levels-of-iodine-131-in-tokyo.html

 

[rhody]

Local News Radio is reporting the core for reactor #1 is compromised and will complicate efforts to contain radiation. A quick scan of local cybernews came up empty. Personally, I am surprised since the explosion at reactor #3 was greatest. On second thought though, imagine you sneezing and trying to suppress it to contain it, that may do more damage than letting it fly. I hope they (media source ) are incorrect. I reported this in the tsunami thread as well and am repeating it here.

Rhody...

P.S. Unlike Chernobyl, the 6 reactors are close to water, and one would assume, the water table. If I remember correctly they pumped liquid nitrogen near the burning core from wells driven at an angle to converge below where the core was. Might this be a desperate measure now given consideration, given the circumstances ?

Finally, I would think they would be considering using heroic, self-sacrificial robots to do some of the dirty work of inspection at deeper levels, (if possible) to assess reactor integrity and containment around it. It may not be possible given the situation, but it was a thought.

Edit: 6:38 am The same radio news reiterated the story 15 minutes later with an official audio newsclip of what sounded like a Japanese reporter who said it was reactor #3, not reactor #1 as I reported above. In the race to be the first, sometimes these folks get it wrong.

Thanks Astronuc for your explanation on Mox fuel many posts ago, but I know you already know that.

 

[jlduh]

@FRED: yes the quality of the video in not very good, but on the reactor 3 what is shown is not, in my opinion, the "things" that has been extracted from the first video (the supposed rods), i only see here (seeing means guessing on this video) structural steel from the roof. The sticks had a different appearence and were on one side (if i remember) of the building, ready to fall down. I would need to see the good quality video, probably soon on youtube anyway.

 

[jensjakob]

More on the possible breach:
http://translate.google.dk/translat...2&eotf=1&sl=ja&tl=en&u=http://www3.nhk.or.jp/

Assumed a valve or a pipe - and the pumping of water into the CV raises the level so it flows throug a broken pipe.

This is a bit less sinister than a breached CV - but still bad - though not "breached CV due to molten core"

 

[jlduh]

@rhody: to my knowledge, the russians were planning to install a big cooling system below the core and that's why they made this tunnel below the reactor with a big room. But finally they didn't do it (why? Maybe not enough time?) and filled the room with concrete to increase the protection towards the phreatic water. The corium finally stopped his way before any contact to water. I don't know if some data have been released since on how deep it went and stopped.

For those new to the forum, i put again the link towards the video "The battle of Tchernobyl" in english (i found a direct complete version in one part on google videos instead of the previously 10 parts on you tube):

http://video.google.com/videoplay?docid=-5384001427276447319#

In the case of Fukushima plant, it seems that the concrete below the reactors ("radier" in french, don't know the name in english sorry) should be around 8 to 10 meters thick, some experts here talk about a speed of progression (very dependant on many factors anyway) of the corium in the concrete of around 1 meter per 24h (which is impressively quick). Anyway this shoud be quickly seen from outside because there shoud be a big amount of gas released from the interaction.

But again, the big fear is water + corium. And this can be before it contacts the concrete. Hope not.

 

[Gilles]

I think the only way for the corium to cool and recrystallize is to increase the surface/volume ratio, so that the inner warmth produced by the remnant RA can be dissipated at a small enough temperature. I understand that this happened in Tchernobyl - once the vessel was breached, the corium flowed in the basement and spread sufficiently to solidify. I guess it is a desperate enterprise to try to confine the fuel into the reactor with broken cooling system - the only possible way is to let the corium melt and go underground, hoping it will spread enough to cool and be stopped by the concrete slab - and not meet the water table.

 

[jlduh]

Hi Gilles, as you can see in France newspapers are clearly changing their mood today concerning the crisis, the optimism of the last days ("we switched on the light in control rooms") is sliding to something slightly different...

As is said earlier, to some extent the Tchernobyl accident, even worse from "scratch standingpoint" (explosion at full power -reactivity accident- with no containment and big graphite fire), presented to my opinion some advantages (i hesitate to use this word, really, but let's do it: it's not "absolute" words but "relative" words...) for the later stages of the accident. The core was fully opened and probably dispersed, which let more possibilities i think to cool it, also the dispersion helped to some extent avoiding having a big concentrated mess. I know that all the experts are saying that containment is far better than no containment but as i foresee the possible scenarios, I'm wondering until where this statement is true when we go to extreme meltdown, especially when anyway the containement has failed... and that you have big pools and water close to it at the very bottom.

Is the advantage still an advantage? Not sure, but I would like to be convinced by others of the the opposite...

As i understand the moves and "improvements" in the newest generations of reactors (like EPR in France), it's clear that after the TMI and Tchernobyl accident they considered these things as more probable and tend (if I'm not wrong) to reduce at the maximum the amount of water close to where the core could melt and as you said to design the thing so a melted core could lay down on a big surface like in a cendar (coated with ceramics in the EPR). Im' not saying that this is better (because it's also much bigger power in one reactor...) but at least this is from what they analysed as sufficiently risky to make changes. This can inform us a little bit on the current situation.

 

[rhody]

I think the only way for the corium to cool and recrystallize is to increase the surface/volume ratio, so that the inner warmth produced by the remnant RA can be dissipated at a small enough temperature. I understand that this happened in Tchernobyl - once the vessel was breached, the corium flowed in the basement and spread sufficiently to solidify. I guess it is a desperate enterprise to try to confine the fuel into the reactor with broken cooling system - the only possible way is to let the corium melt and go underground, hoping it will spread enough to cool and be stopped by the concrete slab - and not meet the water table.

Gilles, jlduh,

Thanks for the corium background, I understand the potential risk it poses if exposed to water. I think we need an expert opinion here, Astronuc, Dean would you care to inform us on what our options are at this point ?

Rhody...

 

[Lefteris]

Thank you all for your information and opinions on the situation. It really is not looking good, and as you all said it basically boils down to personal choice whether to leave Tokyo or stay. For now at least it seems safe to drink tap water with 51 Bq/kg (having fallen more since yesterday's 71 Bq/kg) as reported by Kyodo news agency here: http://english.kyodonews.jp/news/2011/03/81023.html


I will definitely keep reading this thread to try and get a better understanding of the situation and the dangers posed to me and my loved ones here in Tokyo so that we can make well informed decisions.

 

[havemercy]

If what you are saying since this morning is right, they have lost 10 days in triyng to cool down the reactor number 3 in stead of (if this was possible) going in the basement of the reactor to evacuate the water and/or to arrange a tunnel in the soil as they have done it in Tchernobyl.

The soil there is a tectonic one, so they must have installed very solid basement to suport the weiht of the reactor, i. e. more that the 8 - 10 meters you are quoting.

Don't we have the plans or photographs of the construction of reactor number 3 ?

Also the consumption of the concrete by the corium should have released very high quantities of smoke, charged with specific radioactive elements, which so far has not been observed if i am not wrong.

 

[AtomicWombat]

What is this feature? It looks like the top of a whiskey distillery. Note the round opening at the top.

If it is indeed the the top of the reactor it is in the wrong place, suggesting the reactor was destroyed by the explosion in building 3, which has been my "best guess" for some time.


Sorry if this has already been commented on; I've been away for a few days.

 

[jensjakob]

I think that the round feature is the top of the tank just above it

 

[jlduh]

For Japanese people on this forum, i repost this recent (MArch 23) radioactivity study posted earlier here, from US campaign, it clearly shows that the North/North west zone of Fukushima has been so far the most contaminated probably because of winds and/or winds+rain.


http://www.slideshare.net/energy/ra...om-fukushima-area-march-22-2011?from=ss_embed

http://energy.gov/news/10194.htm

 

[artax]

Fascinating analysis and discussions on here.
The containment explosion hypothesis seems a likely explanation for the multiple explosions heard during the reactor 3 event. ie pop 1 being the pressure vessel, pop2 being the primary containment, and then pop 3 being the unpressurised hydrogen in the roof void. Although I would not have expected such large durations between each pop, and there are no visible signs of 3 independent explosions.

To add another area of curiousity, has anyone considered what the grey area that appears to have emanated from reactor 3?

http://patrick.reformstudios.com/p.jpg

I know I'm going back a long way here, but this grey stuff (did you work out what it was?) seems to have been ejected in two directions 180 degrees apart Not quite perpendicular to building layout) as there's some on the roof of the building bottom right, that I think has a hole in it (out of shot). the hole suggesting this material to be either very heavy or very hot.

 

[|Fred]

I can hardly see how one would prefers No containment, full dispersion, combustion.
I really should not brag, but I feel that the press you are mentioning, has a really narrow understanding on the matters at hand.

The 10 000 time higher radioactivity of the water found lately, compare to the radioactivity found in a working reactor, was to be expected: We knew from the start that some Rod melted..
Now we have an indication of a recent leak in the containment (somewhere)

 

[artax]

There's some new video of the reactors from Russia today here:-

http://www.youtube.com/watch?v=97IRb3PH-Gk&feature=player_embedded

seem to be edited from here

http://www.youtube.com/user/YomiuriShimbun

and is it currently snowing over there or is that stuff emanating from the reactors?

It was snowing! ;-)

 

[curie]

Has anyone heard officially that there has been an upgrade to INES level 6? I've seen it around the web but it doesn't seem like a formal announcement.

 

[rhody]

Thank you all for your information and opinions on the situation. It really is not looking good, and as you all said it basically boils down to personal choice whether to leave Tokyo or stay. For now at least it seems safe to drink tap water with 51 Bq/kg (having fallen more since yesterday's 71 Bq/kg) as reported by Kyodo news agency here: http://english.kyodonews.jp/news/2011/03/81023.html


I will definitely keep reading this thread to try and get a better understanding of the situation and the dangers posed to me and my loved ones here in Tokyo so that we can make well informed decisions.

Lefteris,

I am glad you found us, I just did a google search on the title to this thread and it came up in the top ten list, and to PF's credit , the folks here strive to provide as accurate and timely information as possible. I did a thread contribution count and it is over 250 members (many new because of the reactor disaster) and climbing (no bad pun intended).

Rhody...

 

[havemercy]

Following french ASN, the cooling of reactor n° 3 with pure water failed.

"Communiqué de presse n°20 du 25 Mars 2011 à 10h00
25/03/2011 10:46"

"L’exploitant poursuit par ailleurs l’injection d’eau de mer pour refroidir les réacteurs n°1, 2 et 3. Une tentative d’alimentation du réacteur n°3 en eau douce a échoué, vraisemblablement en raison des conditions radiologiques d’intervention. "

http://www.asn.fr/

 

[Borek]

and is it currently snowing over there or is that stuff emanating from the reactors?

IMHO it is snowing, it is visible both in closeups and in some more general views. After all it is March 23rd, so nothing unusual.

 

[jlduh]

Ok, i would like to bring some more material here. Lots of things to summarize.

The first thing is that i just captured several shots from the live NHK world when they were talking about the 3 workers injured in the basement floor beacuse of the contaminated water. They we're asking a specialist from Tokyo University where this water could come from and he had a nice drawing which i think is a new important element for our analysis here because it seems quite accurate, and it's a transversal cut view through the reactor and turbine building. I let them big if no problem for the forum admins because it's much easier to see some details (the resolution is not excellent).

I post them first and will add infos and comments after.

1
http://www.netimago.com/image_182135.html

2
http://www.netimago.com/image_182136.html

3
http://www.netimago.com/image_182137.html I have a 4th one which completes the overall view of the buildings and layout which is a view from the top, a cut view also, at the level of the basement (i would say at the ground level approximatively).http://www.netimago.com/image_182143.html

Position of the workers injured by the highly contaminated 15cm to 30 cms water laying on the floor:

A) Based on the infos the guy from Tokyo University gave, the 3 workers were in the lowest room, between the torus room (on the left) and the turbine (on the right), where the blue pipe linking the reactor anf the turbine (steam pipe) goes down (on pictures 1 to 3).

B) the guy situated them on the other drawing (picture n°4) close to the big red inscription at the bottom right of the image (so quite far away from the reactor position).

The specialist interviewed also said that he doubts the water could come from the spent fuel pool (because of the level of contamination), but said it could come from a broken pipe coming from the reactor. He also said that the day before, an other shift reported no water here. Very surprisingly (for me), then didn't evoke the possibility that this water could also come from the suppression pool which is almost at the same level just behind the wall on the drawing...

These drawings give some interesting informations, we see the level at which the suppression pool is installed (quite deep under the ground) but we also see that the turbines are actually well under the ground either!

That's really scary when you think about risks of flooding... By the way, this probably means that seeing the flooding of the plant from the helicopter shot (just after the tsunami), these rooms have been flooded also? What do you think? Then they would have needed to empty them which could explain the time spent to access these areas?

I'm very surprised to see this kind of layout for the turbine an connecting buildings...

Right AntonL, we were guessing pretty well with the bits of infos everybody brings here. The puzzle is assembling.

Something else: looking at all these new informations on what's inside, i relate the position of the turbines and the position of the big hole in the roof of this turbine building: was this hole done by a big debris coming down after the explosion or was it done DURING the explosion by one of the turbines just blowing out? The hole is right at the top of the turbines:

http://www.netimago.com/image_182148.html

EDITED: Coming back to the relative level of the torus and the turbine to the ground level, one can evaluate how deep these are below the ground level: the reactor vessel is (if no mistake) around 5,4m in diameter, the bottom of the torus (which not so far in diameter than the RPV) seems then to be at around -1,5 (and even more?) "reactors diameter" below the ground (sorry for this approximate unit of measurement, but at least no conversion units problems!). From the TEPCO tsunami study (which proved exact in showing the buildings below the ground! I was not understanding this... and not believing it! But their scale is misleading: the height of the platform relatively to sea level seems as high as the reactor building, which is obviously untrue!)

http://www.netimago.com/image_182149.html

we got the info that the platform was at +10 to +13m from sea level. Soooo... do you come to the conclusion that the bottom of the plant floor (which is visibly the torus supported by concrete plots) is probably only a few meters above actual sea level?

 

[Gilles]

Also the consumption of the concrete by the corium should have released very high quantities of smoke, charged with specific radioactive elements, which so far has not been observed if i am not wrong.

I don't really know what happens when corium meet a concrete slab - I think of some kind of reaction between silicates and molten metals, leading to further fusion of the slab. Not sure it is supposed to emit a lot of smoke : black smoke is usually associated with incomplete combustion of organic materials with emission of fine carbon particles (soot)- well they may be some rubber, isolated (!) cables, and so on, under the reactor, but I'm not sure this represents a large amount of material.

 

[AntonL]

Ok, i would like to bring some more material here. Lots of things to summarize.

The first thing is that i just captured several shots from the live NHK world when they were talking about the
3 workers injured in the basement floor beacuse of the contaminated water. They we're asking a specialist from
Tokyo University where this water could come from and he had a nice drawing which i think is a new important
element for our analysis here because it seems quite accurate, and it's a transversal cut view through the reactor
and turbine building. I let them big if no problem for the forum admins because it's much easier to see some details
(the resolution is not excellent).

I post them first and will add infos and comments after.

I have a 4th one which completes the overall view of the buildings and layout which is a view from the top,
a cut view also, at the level of the basement (i would say at the ground level approximatively).http://www.netimago.com/image_182143.html

Position of the workers injured by the highly contaminated 15cm to 30 cms water laying on the floor:

A) Based on the infos the guy from Tokyo University gave, the 3 workers were in the lowest room,
between the torus room (on the left) and the turbine (on the right), where the blue pipe linking the reactor
anf the turbine (steam pipe) goes down (on pictures 1 to 3).

B) the guy situated them on the other drawing (picture n°4) close to the big red inscription at the bottom
right of the image (so quite far away from the reactor position).

The specialist interviewed also said that he doubts the water could come from the spent fuel pool (because
of the level of contamination), but said it could come from a broken pipe coming from the reactor. He also
said that the day before, an other shift reported no water here. Surprisingly (for me), then didn't evoke the
possibilty that this water could also come from the suppression pool which is almost at the same level...

Not Bad - https://www.physicsforums.com/showpost.php?p=3207270&postcount=1045"

OK I made a mistake I thought is as upper level but now we know it is the basement

 

[|Fred]

I would like to point out a few thingy

March 20th
Reactor 3 Pressure = 250-290 KPa
PCV Pressure= 310 Kpa
Suppression Pool Pressure = over 400 KPa out of scale

Preparation to lower the pressure was carried. Judging from the situation, immediate pressure relief was not required.

March 23
Reactor 3 Pressure = 135-0 KPa
PCV Pressure= 100
Suppression Pool Pressure = down scale

March 24
Reactor 3 Pressure = 142-0 KPa
PCV Pressure= down scale
Suppression Pool Pressure = down scale

March 25th
Reactor 3 Pressure = 139- 0 KPa
PCV Pressure= 107 Kpa
Suppression Pool Pressure = 194 KPa
===========================================

I think that the Reactor pressure sensors are compromised, one likely dead.
the Down scale indicated a dé pressurization of the PCV.

 

[AntonL]

I
I think that the Reactor pressure sensors are compromised, on likely dead.
the Down scale indicated a dé pressurization of the PCV.
taking into considération the recent leak , It seems possible that both PCV and and Reactor are both compromised since the 20th

It must be a relative slow leak, I would imagine a valve not holding the pressure
and now the contaminated steam is escaping, which condenses to the water
the basement acting as a containment area.

 

[havemercy]

Sorry to step back regarding the neutrons. I heard that the water has the effect to slow down the speed of the neutrons.

If this is correct, in the Spent Fuell pool, the neutrons with high speed will go through the fuell without making contact with the fuell and thus reduce the nuclear reaction.

If they add water, it will reduce the speed of the neutrons that will making more contact with the fuell and then increase the nuclear reaction.

The fact to put water in the pools will accordingly have the effect of making more nuclear reaction, isn't it correct ?

 

[|Fred]

It must be a relative slow leak, I would imagine a valve not holding the pressure and now the contaminated steam is escaping, which condenses to the water
the basement acting as a containment area.

I edited my post as I did not gave it enough sensible thoughts :)

 

[jlduh]

@Havemercy: my understanding is that water (not bored of course) increases the reaction and that steam reduces it, and that this is a way to control the reactivity and the reactor in a BWR. But answers from specialists would clarify that...

 

[Maclomer]

In all of the reactors (setting aside the spent fuel pools) the absolute imperative is to maintain cooling by whatever means is feasible and, however it is done, active cooling will probably be needed for many months.

Right now we know some of the cooling is done by directing water jets onto the exterior of the containment and the runoff will go into the ocean. If the containment is breached, that runoff will be radioactive so then there is bound to be a continual emission by this route. Unavoidable.

Now my question:
To what degree is cooling water, and so it seems, seawater, being injected directly into the cores (for example Number 3) and is this water is being heat-exchanged in a closed loop; or are they injecting the water and then allowing the steam to escape (people have commented here about salt build-up)?

I ask this because, at the same time, we hear about 'restarting the cooling pumps', especially for Number 3, using this newly laid power line, which implies to me that an intact cooling loop with proper heat exchange may still be possible, at least for some of the reactors.

 

[Gilles]

I think water in general increases the reaction rate by slowing neutrons. It's just that water vapor is much less dense than liquid, so the effect of steam is to decrease the rate relative to liquid water (negative void coefficient). In reactors using graphite as a moderator like RBMK , it was positive , because water acted essentially as neutron absorber and not as a moderator. That's the same for Pu-Na fast breeder ...

 

[|Fred]

Reactor 1 (not compromised) but under heavy stress
Reactor 2 stabilized (may be wishful thinking)
Reactor 3 (compromised, not necessarily the vessel it self may be only in the pipe of the cooling system and the containgment)

 

[artax]

There's a long but interesting doc. here on spent fuel storage (wet and dry):-

http://www-pub.iaea.org/MTCD/publications/PDF/te_0944_scr.pdf

 

[TCups]

Studied some nuclear chemistry at uni a long time ago hence my interest but I would have to research those isotopes.
However the news here did mention that the ALLOWED UK levels for infants in tap water used for drinking (making up milk) are 5 TIMES HIGHER than those allowed in Japan... so I wouldn't worry at all.
The main reason Iodine is important is because the body has some in it always (thyroid gland) and can't tell the difference between the active isotopes and the natural ones. So if you take the Iodide pills, the iodide atoms (ions) just displace the radio ones very quickly before they've been their long enough to have any effect.
I'm pretty sure the authorities are tellining the truth about the tap water, and washing with it will be no problem at all... and drinking!
If I was in Japan now, I would just avoid the exclusion zone and don't go swimming in the sea!

RE: IODINE PILLS & IODINE UPTAKE BY THE THYROID

Normal iodine will not, I believe, displace radioactive I-131 that has already been taken up by the thyroid gland. The purpose of the iodine pills is to effectively flood the normal biologic uptake of trace amounts of iodine with the normal, non-radioactive isotope, and suppress any further uptake of iodine, ie, radioactive iodine, by the thyroid. After a large dose of RAI (radioactive iodine), potassium iodide will do little good.

 

[Reno Deano]

Thanks Reno, so your explanation is that it's because there was no power available...

So the only vent they could open was inside the building, there was none actionnable toward the outside (what a pity...). Then that was a constraint, not a choice (like to avoid radioactive venting outside), right?

Are we talking about a valve that a man had to actionnate physically being close to it?

The reason why I'm asking these questions is that it seems that a modification has taken place in the US after the TMI accident under the NRC requirement, with the installation on all BWR reactors in the US of a so called "hardened vent" which is a direct realease to the atmophere to depressurize the containement. THis was to avoid precisely H2 release inside the building. Then the question is: did the japanese had this hardened vent? I have the impression that these vents are the big structures (like antennas) that we see close to every reactor (right or wrong?) but in this case it means that they still couldn't activate them because no power (seems not to "hardened" to me but...).

The Reactor Accident off gas system (shielded filtration - carbon and HEPAs) is within the reactor building. I am assuming it worked until the station black out. Then the valves failed shut. I do not know if they had hydrogen igniters on the system (but doubt). The system is located above the reactor vessel level of the plant. That could have been the location of the first expolsions and when damaged the gas vented naturally to the reactor building via numerous paths, eventually finding their way to the top of the reactor building (reactor work platform area). The other off-gas system is the normal one that allows filtration and decay of radioactive short lived gases and is generally under ground with a long decay loop before heading for the stacks. I have inplant experience with several of the BWR models, but am getting long in the tooth, and my memory gets sketchy at times. Also, I have little patience with conjecture based on hearsay and not facts.

The beta exposures while high are not approaching any significant Equivalent Whole Body Dose. Cobalt therapy cancer patients received significant burns of their skin when treated. Since the workers dosimetry did not likely measure beta radiation, the concern was based on isotopic knowledge of the radioisotopes in the water and the large penetration radiation component, and the fact that their boots were full of water. Beta exposure is measured in Grays anyway and depending on the amount of skin involved (largest organ of the body) is converted to Equivalent Whole Body dose at some later time, if significant.