Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Joe Neubarth]

NHK WORLD:

"Caesium 141 found in plant."

Half life 24 seconds ? Please explain

That is as far as it could get before it died.

 

[Astronuc]

An other subjet: can somebody give me a good explanation of why Tepco had to vent the H2 inside the buildings (in the top floor) instead of outside? This looks an odd way of doing it, considering that there was a risk of explosion. Why inside instead of outside? This looks strange to me and i find no analysis or answer on this point.

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.

 

[Astronuc]

NHK WORLD:

"Caesium 141 found in plant."

Half life 24 seconds ? Please explain

That doesn't make much sense to me. The half-life is very short, and that of Ba-141 and La-141 is much longer.

The precursor Xe-141 has an even shorter half-life, so there shouldn't be any significant accumulation of Cs-141 outside of containment.

 

[Bodge]

That doesn't make much sense to me. The half-life is very short, and that of Ba-141 and La-141 is much longer.

The precursor Xe-141 has an even shorter half-life, so there shouldn't be any significant accumulation of Cs-141 outside of containment.

I'm guessing this must have been a mistranslation. Cs-131 ?

 

[Astronuc]

I'm guessing this must have been a mistranslation. Cs-131 ?

I was wondering about that, but I'm not sure.

Here's the radionuclides around Cs-131, 133. Xe-131 is stable, so any Cs-131 should be a direct fission product.

 

[Astronuc]

In monitoring failed fuel, the industry typically measures Xe-133, Xe-135, Xe-138, Kr-85m, Kr-87 and Kr-88, and I-131,132,133,134,135.

Cs-134 and Cs-137 are also measured and the ratio can give some estimate of burnup.

Np-239 is measured and is an indicator for tramp fuel particles or released fuel from breached fuel rods.

 

[JUrban]

An other subjet: can somebody give me a good explanation of why Tepco had to vent the H2 inside the buildings (in the top floor) instead of outside? This looks an odd way of doing it, considering that there was a risk of explosion. Why inside instead of outside? This looks strange to me and i find no analysis or answer on this point.

It's being reported that after one of the disasters (don't remember which one) the US forced reactor retrofits for hardened vents to avoid venting into the buildings, but it's a good chance the Japanese did not follow suit.

 

[JUrban]

The fresh water idea sounds essential and should have been actioned 10 days ago.

Thanks. Yeah for better or worse fairly obvious ideas still need all the pieces to come together to emerge from the darkened idea space, and for disaster situations like this, that fact is scary.

 

[TCups]

REGARDING THE PHOTOGRAPHIC EVIDENCE AND NATURE OF EXPLOSIONS, UNIT 1,3, 4

I am updating some of the earlier photo analysis that took place earler amongst the forum participants and that may not yet have been reviewed by those newer posters who have recently joined.

Look again, carefully, at the photos that AntonL referenced from Der Spiegel (page 23, post #363)

http://www.spiegel.de/images/image-193170-galleryV9-njkp.jpg
Reactor 4

http://www.spiegel.de/images/image-193230-galleryV9-ovfc.jpg
Reactor 4

http://www.spiegel.de/images/image-193230-galleryV9-ovfc.jpg
Reactor 4

http://www.spiegel.de/images/image-193165-galleryV9-kzvg.jpg
Reactor 3

http://www.spiegel.de/images/image-193254-galleryV9-gmmj.jpg
Reactor 3 (corrected, original post says Reactor 1)

from MSNBC
http://msnbcmedia3.msn.com/j/MSNBC/Components/Photo/_new/110312-reactor-vlg-5p.grid-4x2.jpg
Reactor 1

I don't know how I missed this before, but here is what I think I see. The building designs and overhead cranes in 3 and 4 are different than in 1. The overhead cranes in 3 and 4 are mounted atop massive steal beams that run north-south, and that are supported, indeed have to be supported by the reinforced concrete columns on the east and west sides of the building. The weight and size of the beams that are the tracks for the crane, in turn, reinforce the bearing weight-bearing columns of the top floor of bldgs 3, 4.

The hydrogen explosion in the top floor of 4 spares most of the roof and all of the columns on the east and west sides because of this relationship to the construction and weight-bearing functions mentioned. After the explosion, you can see that the structural damage to the roof and most of the structural damage to the side walls of Bldg 4, are therefore most severe at the north and south ends of the building.

The same holds true for Bldg 3, except that

1) the explosion at Bldg 3 was much more powerful, and
2) the explosion at Bldg 3 results in the north wall weight-bearing columns buckling and the crane structure itself sliding or being blown off of the rails and falling from the top floor of Bldg 3 to the top of the smaller, adjoining building below on the north side of Bldg 3.

The fuel handling machenery (green) still sits atop the SFP of Bldg 4, but not at Bldg 3. The SFPs are at the southeast corner of both Bldg 3 and 4 as has already been confirmed.

The concrete panels between the structural weight bearing columns of Bldg 3, because of the much larger size and power of the blast in Bldg 3, resulted in the concrete panels between the weight bearing columns on the east and west sides becoming more effective "bullets" when they blew out en mass, from between the columns, doing the damage to the adjacent roofs of Turbine Bldg 3 and the building in back, on the west side of Bldg 3. The size and power of the blast also did much more damage to the superstructure of the roof girders of 3 than 4, but it would still appear that the roof girders over the drywall containment plug of Bldg 3 are not completely destroyed after the explosion. Hence, the drywall containment plug was not blow straight upward.

The annotated image below was modified from the original, at DigitalGlobe.com

The larger explosion at Bldg 3 is annotated. The short arrows are the paths of the "bullet-like" blow out of the east and west side panels of Bldg 3.

The long arrow shows the damage to the north-side structures adjacent to Bldg 3 done by the falling crane, visibly absent at Bldg 4.

The rectangles show the location of the highest rates of measured radioactivity, presumably at ground level, adjacent to Bldg 3, and taken from this Diagram, posted earlier by jlduh (#957), original reference not known.

http://www.monsterup.com/upload/1300925395929.jpg

This suggests to me, but it has not been confirmed, that the debris blasted from Unit 3 carried radioactive contaminants, either from the SFP or from the Unit 3 reactor core, or from both.

And this close-up of steam venting in the region of the SFP of Unit 3, I believe, reinforces the opinion (speculation on my part) that the containment of Unit 3, more specifically, the drywall containment at the location of the fuel transfer gate(s) and chute to the SFP is the source of the breech and the venting steam (diagram following).

This image of debris atop Bldg 3 suggests to some (myself included) that the blast displaced spent fuel rods from Unit 3's SFP, but this has not been confirmed.

 

[AntonL]

NHK reported that water in basement 3 has 10000 x the radioactivity as the water inside a normal operating reactor, hence the assumption that unit 3 containment may be breached, leaking water into basement 3.



This is the slide displayed while above was being reported.

This slide also confirms to me that the design parameter of a 5.7m Tsunami wave was an afterthought. The height as I in a previous mail suggested is determined by design need to keep basements above seawater levels as can be seen above That height dictates a maximum Tsunami wave such that pump cabins for coolant do not get destroyed. Ground level at reactor is about 15 metres as per earlier Tepco releases.

 

[TCups]

NHK reported that water in basement 3 has 10000 x the radioactivity as the water inside a normal operating reactor, hence the assumption that unit 3 containment may be breached, leaking water into basement 3.

Could one not just as easily conclude that the contamination comes from damaged fuel rods in the SFP with the leakage coming from the damaged SFP, or from dispersed fuel rods outside of the SFP that had been spayed with water over the last several days?

 

[Bodge]

Nobody has commented on my analysis, so I'll post it again. I was honestly startled.

The IAEA have just measured very high beta/gamma contamination 4,900,000 beq / metre squared in Fuk. Pref.

"At distances between 30 and 32 kilometers from the Fukushima Nuclear Power Plant, in a north westerly direction from the site, dose rates between 16 and 59 microsievert per hour were measured. At these locations, the results of beta-gamma contamination measurements ranged from 3.8 to 4.9 Megabecquerel per square metre. At a location of 21 km from the Fukushima site, where a dose rate of 115 microsieverts per hour was measured, the beta-gamma contamination level could not be determined."

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

Here is a map of Chernobyl's "Zone of Alienation"

I converted 40 curies / square km to 1.48 Megabeq / square metre

Also 1.48 is mentioned here:

http://books.google.com/books?id=g3...age&q=chernobyl cs soil contamination&f=false

We seem to have 4.9 Megabecquerels in Japan

edit: Forgot to mention not all of the radiation detected yesterday by the IAEA was from Cs137, there will be Iodine,Strontium,Cobalt etc and maybe Plutonium too. Also one site was "unmeasureable", but mSv was highest at that point !

 

[AntonL]

Could one not just as easily conclude that the contamination comes from damaged fuel rods in the SFP with the leakage coming from the damaged SFP, or from dispersed fuel rods outside of the SFP that had been spayed with water over the last several days?

Makes more sense to me as water does not flow uphill - see basement levels of torus and turbine building of slide posted earlierTCups please note location of reactor relative to upper structure

 

[TCups]

Nobody has commented on my analysis, so I'll post it again. I was honestly startled.

If the original data are correct and your analysis of the data is correct, then, the obvious comment is "gee, that is really hot!"

Do we know which were the source of the radionuclides emitting that level of radioactivity and how long their half lives are? If these represent the volatile components, brought to ground by rain or settling dust, for example I-131 with a half life of 8 days, then the radioactivity will be very different a few weeks from now. If, on the other hand, there are longer half-lived fission byproducts from the damaged fuel rods in the core or SFP, then the contamination will by its nature, be much worse and a much more long-lasting problem. Chernobyl was the later. As far as is yet know, Fukushima will be the former.

 

[Bodge]

If the original data are correct and your analysis of the data is correct, then, the obvious comment is "gee, that is really hot!"

Do we know which were the source of the radionuclides emitting that level of radioactivity and how long their half lives are? If these represent the volatile components, brought to ground by rain or settling dust, for example I-131 with a half life of 8 days, then the radioactivity will be very different a few weeks from now. If, on the other hand, there are longer half-lived fission byproducts from the damaged fuel rods in the core or SFP, then the contamination will by its nature, be much worse and a much more long-lasting problem. Chernobyl was the later. As far as is yet know, Fukushima will be the former.

The IAEA simply had this to say:

"Measurements will be taken to determine more precisely the actual radionuclides that have been deposited."

 

[83729780]

Could one not just as easily conclude that the contamination comes from damaged fuel rods in the SFP with the leakage coming from the damaged SFP, or from dispersed fuel rods outside of the SFP that had been spayed with water over the last several days?

What do you make of the fact that the exposure took place inside the turbine building that had debris smash through its roof after the explosion?

 

[TCups]

What do you make of the fact that the exposure took place inside the turbine building that had debris smash through its roof after the explosion?

I don't know for sure. On consideration, though, if the exposure were from pooled water in the building floor, it seems more likely that the contamination came in with the water, not from falling debris. That said, I believe there might have been rain there. Rain or sprayed water leaking through a large hole in the roof could easily be one route, if not the main rout for water accumulating in the building, versus, for example, ground water seepage from a crack in the foundation.

What do you think?

 

[AntonL]

I don't know for sure. On consideration, though, if the exposure were from pooled water in the building floor, it seems more likely that the contamination came in with the water, not from falling debris. That said, I believe there might have been rain there. Rain or sprayed water leaking through a large hole in the roof could easily be one route, if not the main rout for water accumulating in the building, versus, for example, ground water seepage from a crack in the foundation.

What do you think?

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

 

[TCups]

The IAEA simply had this to say:

"Measurements will be taken to determine more precisely the actual radionuclides that have been deposited."

Exactly. It may be correct that "the sky is falling!", but it depends on what is in the sky that was the "fallout" that will determine whether or not it will be a long term problem. It's certainly not yet time to swallow the gun.

 

[TCups]

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. ()

 

[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.