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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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DrDu
#1117
Mar25-11, 04:47 AM
Sci Advisor
P: 3,596
Quote Quote by Lefteris View Post
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
#1118
Mar25-11, 04:50 AM
P: 159
Quote Quote by Lefteris View Post
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
#1119
Mar25-11, 05:08 AM
P: 312
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
#1120
Mar25-11, 05:10 AM
P: 123
Quote Quote by |Fred View Post
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
#1121
Mar25-11, 05:22 AM
P: 9
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/weltspieg...t/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 im 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
#1122
Mar25-11, 05:31 AM
P: 468
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-pacifique...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 controled 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
#1123
Mar25-11, 05:34 AM
P: 312
@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-...hapter_42.html .
intric8
#1124
Mar25-11, 05:43 AM
P: 24
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.c...-in-tokyo.html
rhody
#1125
Mar25-11, 05:46 AM
PF Gold
rhody's Avatar
P: 765
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
#1126
Mar25-11, 05:49 AM
P: 468
@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
#1127
Mar25-11, 05:59 AM
P: 123
More on the possible breach:
http://translate.google.dk/translate...3.nhk.or.jp%2F

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
#1128
Mar25-11, 06:03 AM
P: 468
@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?do...1427276447319#

In the case of Fukushima plant, it seems that the concrete below the reactors ("radier" in french, dont 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
#1129
Mar25-11, 06:14 AM
P: 30
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
#1130
Mar25-11, 06:29 AM
P: 468
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
#1131
Mar25-11, 06:34 AM
PF Gold
rhody's Avatar
P: 765
Quote Quote by Gilles View Post
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
#1132
Mar25-11, 06:41 AM
P: 9
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
#1133
Mar25-11, 06:48 AM
P: 21
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
#1134
Mar25-11, 06:48 AM
P: 150
Quote Quote by curious11 View Post
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.


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