Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MiceAndMen]

For the sake of clarity, a question and a curse.

Is the use of the term 'meltdown' used here to be considered a partial meltdown?

I understand this to mean the melting of fuel rods and the relocation of that melt within the reactor vessel. I understand that it does not necessarily mean that corium has formed (the fuel rods could have 'granulated') but that it could be the case.

I also think that it does not mean full meltdown, which I understand is the departure of corium from the reactor vessel to somewhere else - in this case the drywell.

My curse is that the term 'meltdown' is http://oxforddictionaries.com/definition/meltdown" and has been for years, but it has not been defined by the scientific community.

(Perhaps one of the legacies of Fukushima will include a reliable definition of the term and that people will learn it in journalism college).

Do schools still teach journalism? Coulda fooled me. Anyway... the term "meltdown" has no precise meaning, so any and all of your interpretations can be considered correct. In my mind I always associated "melted fuel rods = meltdown" without regard for where the molten core or debris bed relocated to. Maybe there will be new terms introduced to differentiate between melted fuel still in the RPV vs. out of the RPV vs. attacking concrete foundation vs. in the earth. The Eskimos, after all, have more than 1 word for snow. We'll probably end up with a few new acronyms, although once the fuel is out of the RPV it becomes a guessing game as to where it is and what state it's in.

 

[etudiant]

The report you provide could be seen as supporting the numbers etudiant used as the base for his calculations: (4mw for unit 1 and 6mw for 1&3) however the report comes with this caveat:

*Values for the decay heat were calculated based on assuming an infinite reactor operation time prior to shutdown. Infinite operation is a conservative assumption, and actual values may be significantly lower than those that are shown in the figure and table.


So while in a real world situation, with no fuel damage, it appears that the 4mw and 6mw numbers are higher than what would be actually experienced we also need to factor in the point raised by Jorge Stolfi in post #9044.

once the fuel is completely molten, the radioactive elements that remain in the liquid corium will produce 30% of the decay heat power that would be produced by the intact fuel; the other 70% of the decay heat power is due to more volatile elements that will end up elsewhere.


So it appears that Fukushima is currently experiencing a residual heat in unit 1 of 30% of a number which is lower (maybe very much so) than the 4 mw number.

So the heat remaining in unit 1's containment is probably considerably lower than the residual heat in SFP4 on the day of the accident.

There may be reasons why pouring sand (or whatever) on the remainder of the cores is unworkable, but too much residual heat is not likely one of them.

However, if they continue pouring water on the corium the Japanese are certain to win the gold.
Re: #9020 swl "Another year of contaminated steam, then add in the water leaks, and we should be well on our way to that elusive #1 spot (of all time accidents)."

Useful insight, thank you.
It seems logical that the heat generated in the fuel would be less if a lot of the more active volatiles were washed away.
That also means that the amount of steam produced should similarly be less, with less contamination because the volatiles will have been dispersed through the body of lake Fukushima rather that being boiled out of the fuel residual.
Maybe TEPCO could reduce the water injections further, although it is murky whether any water is reaching the residual fuel or whether that fuel is shielded by a deep crust of salt.

 

[mscharisma]

My impression is that they initially underestimated the amount of contaminated water storage that would be necessary, possibly by an order of magnitude. They have already abandoned Plan A and moved on to Plan B.

Sorry for my ignorance, but what is Plan B in that case? I don't recall seeing or hearing anything other than to continue cooling, add storage capacity for water, and hope that AREVA can clean up as much as possible. What did I miss?

 

[Atomfritz]

Evidence of recriticality in reactor 1?

I noticed the increase in I-131 detection on the CTBTO chart matched up with the "erroneous" recordings of radiation spikes in reactor 1's drywell:

http://www.bfs.de/de/ion/imis/ctbto_aktivitaetskonzentrationen_jod.gif
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/out/plot-un1-t-T-full.png

edit: Just noticed at http://ex-skf.blogspot.com/2011/06/arnie-gundersen-on-and-off.html" commenters claim that the CTBTO Iodine spikes match up with increased temps at reactor 3's RPV flange.

Somebody needs to properly correlate the relevant data.

These oscillations are indeed strange.
Remember, even Oklo was an oscillating reactor.
Does there exist any other explanation?
Maybe oscillations caused by water flow or such?

 

[MiceAndMen]

"According to the nuclear regulatory commission, parents WON'T drive to school to rescue their kids. They'll drive away from the nuclear accident and wait for the school buses to come to them."

Riiiiiight... what planet are these guys coming from?

Does he have a cite for that? I seem to recall that during the Shoreham fiasco in New York local authorities claimed that (a) the roads during an evacuation would be clogged due (in part) to parents going to get their kids, and (b) school bus drivers would be AWOL anyway, having gone to look after their own families. I can't believe the NRC just arbitrarily claimed something else. In fact, now that I think about it, the NRC is concerned only with actual radiation releases and does not overly concern themselves with the details of accident response. Outside of seeing that there is some evacuation plan in place, those plans are outside of the NRC's purpose and scope of responsibility.

I'd really like to see him back that claim up, but if I had a nickle for every time I thought that about Gundersen I'd be rich.

 

[elektrownik]

Anyone know what is condition of unit 5&6 ? There is much data for 1,2,3, but not for 5&6, did they enter reactor hall ? RPVs were open because of refueling, so they should be able to make visual inspection of fuel, do we have raw data (like for unit 1,2,3) after earthquake and tsunami ? From simple data we can see that unit 5 was at 150-200C from tsunami time to 3/20 and unit 6 in the same time ~150C, but unit 5&6 were at atmospheric pressure, so there should be much steam, so what about contamination ? And fuel damage is possible ?
what about water level after blackout ?
simple temp data for unit 5&6: http://www.tepco.co.jp/nu/fukushima-np/f1/images/11051612_temp_data_56u-j.pdf

 

[MiceAndMen]

Sorry for my ignorance, but what is Plan B in that case? I don't recall seeing or hearing anything other than to continue cooling, add storage capacity for water, and hope that AREVA can clean up as much as possible. What did I miss?

http://search.japantimes.co.jp/cgi-bin/nn20110513x2.html

That took me about 1 minute to find with Google.

 

[dh87]

Indeed, according to the Cristoph Mueller slides posted earlier, once the fuel is completely molten, the radioactive elements that remain in the liquid melt (corium) will produce 30% of the decay heat power that would be produced by the intact fuel; the other 70% of the decay heat power is due to more volatile elements that will end up elsewhere.

Some of that 70% will escape to the atmosphere, some will be washed out by the cooling water, and perhaps some will be deposited inside the reactor or containment in places and forms that cannot be easily washed out. In any case those 70% are a big contamination problem but should not pose much of a heat management problem. Is this correct?

On the other hand the corium will contain many long-lived isotopes which could be a huge health hazard if they were ejected to the atmosphere. While the contribution of an element to the heat production rate is inversely proportional to its half-life (among other things), its potential for health damage is largely independent of it, at least for lifetimes up to a decade or two. So, while the corium keeps 30% of the decay heat production, it may include a larger fraction of the total health damage potential of the original fuel.

I can't find the slides that you refer to. Could you or someone provide a link? Thanks.

The residual material isn't volatile and isn't soluble in water. The only way it can be distributed is as dust in an explosion. It could be quite hazardous, but it's not very mobile.

 

[NUCENG]

These oscillations are indeed strange.
Remember, even Oklo was an oscillating reactor.
Does there exist any other explanation?
Maybe oscillations caused by water flow or such?

Questions:

1. Where is the Japan CTBTO sensor? Are the peaks in CTBTO data correlated with wind direction to the sensor from the Fukushima site?

2. Have the peaks been checked for increases in other short half life isotopes?

3. If the peaks are due to short recriticalities shouldn't the increase be followed by an exponential decay from the new peak? It looks like they drop right back to the decay trend that was in place before the short peaks.

4. Shouldn't the Unit 1 drywell radiation detectors show some time delay to the CTBTO sensor unless that sensor is on site.

 

[MiceAndMen]

I can't find the slides that you refer to. Could you or someone provide a link? Thanks.

https://www.physicsforums.com/showthread.php?p=3340995#post3340995

 

[jim hardy]

Am I the only Engineer that sees a two stage explosion on Unit 3? Stage 1: the detonation that creates the flash to the right and then, afterwards Stage 2: the upside going explosion that behaves very similarly to a nuclear detonation, and may be was...
Just loop the video in the link around the explosion and observe the two clear stages of it.

http://www.youtube.com/watch?v=7naSc81WSqA&feature=related

You are not the only person who noticed the event appeared to occur in two stages.
I saw it on TV that morning and have been obsessive about it since.


I can niether rule out nor prove that it may have had some help from neutrons.

There exists a group called "American Nuclear Society , Nuclear Criticality Safety Division" whom one would expect to have analyzed and reassured us by now. The silence is deafening.

One thing Arnie did get right - where information is concerned ranks are closed.

TPTB are avoiding the subject.


satellite 3 minutes after explosion:

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

 

[mscharisma]

http://search.japantimes.co.jp/cgi-bin/nn20110513x2.html

That took me about 1 minute to find with Google.

Thanks for the link although the page currently doesn't load due to "congestion." I could certainly have looked for it myself, but I don't know what you were referring to when you said TEPCO had a Plan B, so obviously I don't know what to search for.

Edit: Page now loaded and I think you may have misunderstood me. What's described in the article in my mind IS Plan A. My question is/was, what if they end up with more water than can be stored/decontaminated/recirculated, then what's Plan B?

 

[Bioengineer01]

Evidence of recriticality in reactor 1?

I noticed the increase in I-131 detection on the CTBTO chart matched up with the "erroneous" recordings of radiation spikes in reactor 1's drywell:

http://www.bfs.de/de/ion/imis/ctbto_aktivitaetskonzentrationen_jod.gif
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/out/plot-un1-t-T-full.png

edit: Just noticed at http://ex-skf.blogspot.com/2011/06/arnie-gundersen-on-and-off.html" commenters claim that the CTBTO Iodine spikes match up with increased temps at reactor 3's RPV flange.

Somebody needs to properly correlate the relevant data.

They don't correlate, I plotted the temperature data for Unit 3 until the 20th

 

[robinson]

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

I still want to know what is in the steam (and occasional smoke) that has been coming out from two locations in what used to be reactor building number three. For almost three months now.

It can't possibly be that nobody can measure this.

I'm especially interested in what looks like a huge tea kettle spout in the middle of the building.

 

[jim hardy]

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

I still want to know what is in the steam (and occasional smoke) that has been coming out from two locations in what used to be reactor building number three. For almost three months now.

It can't possibly be that nobody can measure this.

I'm especially interested in what looks like a huge tea kettle spout in the middle of the building.

Teakettle spout? mark up a photo ... are you speaking of this?

 

[Bodge]

Questions:

1. Where is the Japan CTBTO sensor? Are the peaks in CTBTO data correlated with wind direction to the sensor from the Fukushima site?

2. Have the peaks been checked for increases in other short half life isotopes?

3. If the peaks are due to short recriticalities shouldn't the increase be followed by an exponential decay from the new peak? It looks like they drop right back to the decay trend that was in place before the short peaks.

4. Shouldn't the Unit 1 drywell radiation detectors show some time delay to the CTBTO sensor unless that sensor is on site.

.
.
1. http://www.ctbto.org/map/" (approx 200km and 100km away from Fuk Daiichi)
.
.
2. From WindGuru

 

[mscharisma]

Does he have a cite for that? I seem to recall that during the Shoreham fiasco in New York local authorities claimed that (a) the roads during an evacuation would be clogged due (in part) to parents going to get their kids, and (b) school bus drivers would be AWOL anyway, having gone to look after their own families. I can't believe the NRC just arbitrarily claimed something else. In fact, now that I think about it, the NRC is concerned only with actual radiation releases and does not overly concern themselves with the details of accident response. Outside of seeing that there is some evacuation plan in place, those plans are outside of the NRC's purpose and scope of responsibility.

I'd really like to see him back that claim up, but if I had a nickle for every time I thought that about Gundersen I'd be rich.

Of course, I can't speak for Gunderson and where his information comes from as to parents not picking up their children. I can, however, confirm that at least for the area I live in (southern California, close to San Onofre NPP), that's exactly the plan. See linked document, page 7, point 1.

http://www.sdcounty.ca.gov/oes/docs/ever-ready2009.pdf

I can also confirm that about 20 years ago during an evacuation due to a huge fire, those were exactly the instructions provided to parents: do not pick up your children, the schools will evacuate them themselves. And they did.

 

[Bioengineer01]

They don't correlate, I plotted the temperature data for Unit 3 until the 20th

https://www.physicsforums.com/attachment.php?attachmentid=36212&stc=1&d=1307405325

 

[NUCENG]

You are not the only person who noticed the event appeared to occur in two stages.
I saw it on TV that morning and have been obsessive about it since.


I can niether rule out nor prove that it may have had some help from neutrons.

There exists a group called "American Nuclear Society , Nuclear Criticality Safety Division" whom one would expect to have analyzed and reassured us by now. The silence is deafening.

One thing Arnie did get right - where information is concerned ranks are closed.

TPTB are avoiding the subject.


satellite 3 minutes after explosion:

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

In the photo at the southwest corner of Unit 3 RB it looks like the SBGT pipe might be severed or at least has some debris laying on it. There is no damage to Unit 4 RB yet. If any of you graphics experts can look at this it may be evidence to rule out Hydrogen from Unit 3 causing the explosion or damage in unit 4 through the common stack.

 

[MiceAndMen]

Thanks for the link although the page currently doesn't load due to "congestion." I could certainly have looked for it myself, but I don't know what you were referring to when you said TEPCO had a Plan B, so obviously I don't know what to search for.

One of the key elements of the plan was to flood the primary containment vessels to ensure cooling. They shifted to Plan B when they discovered the cores had melted. They have only a very vague idea right now about how they're going to keep the melted fuel cool. They don't even know where it is.

They continually claim to be surprised by events, when it's obvious (at least to me) that all these things should have been anticipated. It is good they now appear to be making some progress, some very good progress, but I believe they are reacting to events rather than implementing any sort of "plan" designed to take control of those events.

 

[mscharisma]

One of the key elements of the plan was to flood the primary containment vessels to ensure cooling. They shifted to Plan B when they discovered the cores had melted. They have only a very vague idea right now about how they're going to keep the melted fuel cool. They don't even know where it is.

Another important element of the original plan was designed to halt the outflow of contaminated water into the sea. That hasn't gone quite according to plan either. They planned to pump all the water out of basements and underground trenches, but for some strange reason the water refuses to go away.

They continually claim to be surprised by events, when it's obvious (at least to me) that all these things should have been anticipated.

Thanks. I just edited my post while you were typing since the article link did finally work. We may have misunderstand each other. When I was wondering about a Plan B, I was speaking solely of the scenario where too much water accumulates to be stored or decontaminated/reprocessed. What will they do then, i.e., what's their Plan B for THAT scenario? Especially since so far many things have not gone according to plan.

 

[MiceAndMen]

Thanks. I just edited my post while you were typing since the article link did finally work. We may misunderstand each other. When I was wondering about a Plan B, I was speaking solely of the scenario where too much water accumulates to be stored or decontaminated/reprocessed. What will they do then, i.e., what's their Plan B for THAT scenario? Especially since so far many things have not gone according to plan.

Ah, sorry to have misunderstood. That one's easy: http://www.world-nuclear-news.org/newsarticle.aspx?id=29794&terms=float".

But in all seriousness, I think they will just keep expanding the number of tanks brought in from the outside for storage. Is anyone really going to be surprised if it turns out that the water treatment plans are incapable of keeping up with the ongoing accumulation?

 

[mscharisma]

Ah, sorry to have misunderstood. That one's easy: http://www.world-nuclear-news.org/newsarticle.aspx?id=29794&terms=float".

But in all seriousness, I think they will just keep expanding the number of tanks brought in from the outside for storage. Is anyone really going to be surprised if it turns out that the water treatment plans are incapable of keeping up with the ongoing accumulation?

That was precisely my concern and question: How likely does it seem to be that they are going to be able to keep up - assuming nothing else will go wrong and AREVA's plant works as anticipated right away -, and what's next (Plan B) if "keeping up" doesn't work? And since my question came up in response to an alternate cleaning solution or claim thereof posted by someone: what on Earth - if anything - is being done right now to look for alternate solutions? While I understand little of the technical intricacies, I cannot help the impression that, and others have mentioned it before, TEPCO seems to be taking a very linear approach: we try this (Plan A), if it doesn't work, we think of something else (Plan B). Maybe I oversimplify in my non-technical mind, but what about thinking about the "what if it doesn't work" right away rather than later? I hear little official or anything about options, hence I was asking.

And yes, I am mentally preparing myself for the mega float coming up as THE solution again. ;)

 

[Lambert]

Yeah it was a interview of Kei Sugaoka, here is the info from the youtube video before it was nuked:

"Uploaded by laborvideo on Jun 3, 2011

GE Nuclear Inspector And Whistleblower Kei Sugaoka Speaks Out About Fukushima , GE & Obama
General Electric nuclear plant inspector Kei Sugaoka was one of the inspectors at the Fukushima Daiichi plant in 2000. He noticed a crack in the steam dryer which he videotaped. He was later ordered by TEPCO to edit this part of the tape which is illegal in the United States. He went public and some TEPCO managers were fired. He thought that things would change but they have not. Additionally as a result of being a whistleblower he was also fired by General Electric and has been struggling to get the truth out about these dangerous plants. This interview was done on May 5, 2011.
http://www.youtube.com/watch?v=fBjiLaVOsI4&feature=
http://criticality.org/2011/05/whistleblower-shutdown-17-nuclear-reactors/
http://www.nytimes.com/2011/04/27/world/asia/27collusion.html?hpw
http://www.baycitizen.org/disasters/story/inside-japans-failing-nuclear-react ...
http://search.japantimes.co.jp/cgi-bin/fl20040523x2.html
Production of Labor Video Project www.laborvideo.org laborvideo.blip.tv
(c)2011"


most of the links are dead now, kind of crazy... here is another link i found which is also interesting:

http://www.youtube.com/view_play_list?p=0AA0A2E17C94FC6C

Back up if anyone is interested:

 

[razzz]

Back up if anyone is interested:

Thanks for that. Kei is supposedly writing a book.

Well worth the listen.

 

[Lambert]

Thanks for that. Kei is supposedly writing a book.

Well worth the listen.

Yes the book would be an awesome read, Kei's a rock star for sure, id love to have a few pints with him ;-/

 

[Bioengineer01]

That was precisely my concern and question: How likely does it seem to be that they are going to be able to keep up - assuming nothing else will go wrong and AREVA's plant works as anticipated right away -, and what's next (Plan B) if "keeping up" doesn't work? And since my question came up in response to an alternate cleaning solution or claim thereof posted by someone: what on Earth - if anything - is being done right now to look for alternate solutions? While I understand little of the technical intricacies, I cannot help the impression that, and others have mentioned it before, TEPCO seems to be taking a very linear approach: we try this (Plan A), if it doesn't work, we think of something else (Plan B). Maybe I oversimplify in my non-technical mind, but what about thinking about the "what if it doesn't work" right away rather than later? I hear little official or anything about options, hence I was asking.

And yes, I am mentally preparing myself for the mega float coming up as THE solution again. ;)

I managed large engineering teams. You always have your analytical group that needs to think and re-thing everything 10 times until they propose something, those types are great for design work. But for crisis work I had the "drivers", they can think on their feet, they are able to elaborate complex plans in days, rather than months. When you use one group to do the task the other should do, you get a disaster. That is what seems to be happening here, they don't have the right type of people working on the problem. Contingency planning is a basic element of any plan.

 

[mntnfun]

Hi dudes, I registered to ask a question of you:

First, check out this video that purportedly shows radioactive steam being released from somewhere under the first floor of reactor 1:



It seems that this steam must be coming up from the basement of reactor 1. Of course, steam means water is boiling.

If the basement is indeed the source of the steam then consider that we know the basement is flooded with millions of gallons of water.

Now, what in this situation could make millions of gallons of water boil?

Could it be that the nuclear fuel has fallen into the basement, achieved criticality, and is now heating all that water?

 

[dh87]

https://www.physicsforums.com/showthread.php?p=3340995#post3340995

Thank you.

 

[RdFltErr]

You are not the only person who noticed the event appeared to occur in two stages.
I saw it on TV that morning and have been obsessive about it since.

In http://www.youtube.com/watch?v=nw2Aw3komgc" I feel the more telling information is the audio. It actually sounds like three explosions. Assuming that audio is accurate of course.

 

[robinson]

Teakettle spout?

I was just remarking that the steam cloud from the middle location looks for all the world at times like a giant tea kettle boiling away, with this huge cloud of steam coming out. I have little doubt it is from the reactor, and that containment was breached after the explosion. And the pile of nuclear fuel is boiling away the water they keep dumping on it.

That was obvious on March 17th.

What is remarkable is that 'they' just never mention it, much less publish any data on what is coming out of the reactor in the steam, 24 hours a day, every day since the explosion.

 

[RdFltErr]

That was precisely my concern and question: How likely does it seem to be that they are going to be able to keep up - assuming nothing else will go wrong and AREVA's plant works as anticipated right away -, and what's next (Plan B) if "keeping up" doesn't work?

I have been reading everything I could find since the situation began unfolding. In recent weeks, as talk of these water containers has increased, I've yet to find a single report that talks about any significant number of storage units showing up prior to August. It's June now.

My suspicion is that, for at least some period, the sea will be the only possible place to put the excess water. With rain still coming and, I believe, buildings still uncovered, I just don't see how this will work...

 

[swl]

In http://www.youtube.com/watch?v=nw2Aw3komgc" I feel the more telling information is the audio. It actually sounds like three explosions. Assuming that audio is accurate of course.

The explosion sound issue has already been thoroughly discussed and demonstrated to be added to the video after the recording. It is my understanding that the explosions heard on the video are special effects audio not related to the actual explosion.

Please search through this thread to find the specific information.

 

[RdFltErr]

The explosion sound issue has already been thoroughly discussed and demonstrated to be added to the video after the recording. It is my understanding that the explosions heard on the video are special effects audio not related to the actual explosion.

Please search through this thread to find the specific information.

whoops, sorry bout that :-) thank you for the correction.

 

[Quim]

satellite 3 minutes after explosion:
http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

Wow, I missed this picture up until now.

At 3 minutes after explosion there were two distinct and separate sources of steam release: the containment structure and the SFP.

This all but confirms T-Cups theory about the source of the blast coming from under the containment lid.

 

[Quim]

The explosion sound issue has already been thoroughly discussed and demonstrated to be added to the video after the recording. It is my understanding that the explosions heard on the video are special effects audio not related to the actual explosion.

Please search through this thread to find the specific information.

Here it is:

5-14 12:07 AM #7168
westfield

westfield is Offline:
Posts: 1
Re: Japan Earthquake: nuclear plants
Originally Posted by Borek
Please search the thread - it is not clear (at least to some) whether the sound is really part of the recording and whether it was not added from some other

source.
I'll have a stab at making it clear. Been lurking for a few weeks but this audio discussion has driven me spare and caused me to unlurk.

Take it from a career audio professional and\or look at the evidence below, it's not in any way the sound of unit #3 exploding. To me, a glance at the

waveforms is enough to see it's a cut up effects track assembled from a 3 or 4 samples with some tweaks with effects and dynamics.

There are SO many things to speculate about, this audio track shouldn't be one of them. It's fake.

 

[dh87]

Indeed, according to the Cristoph Mueller slides posted earlier, once the fuel is completely molten, the radioactive elements that remain in the liquid melt (corium) will produce 30% of the decay heat power that would be produced by the intact fuel; the other 70% of the decay heat power is due to more volatile elements that will end up elsewhere.

Some of that 70% will escape to the atmosphere, some will be washed out by the cooling water, and perhaps some will be deposited inside the reactor or containment in places and forms that cannot be easily washed out. In any case those 70% are a big contamination problem but should not pose much of a heat management problem. Is this correct?

On the other hand the corium will contain many long-lived isotopes which could be a huge health hazard if they were ejected to the atmosphere. While the contribution of an element to the heat production rate is inversely proportional to its half-life (among other things), its potential for health damage is largely independent of it, at least for lifetimes up to a decade or two. So, while the corium keeps 30% of the decay heat production, it may include a larger fraction of the total health damage potentia of the original fuel.

Mueller divides the fission products into high, medium, and low volatility. At Fukushima, a lot of iodine and some cesium probably were boiled off (together with all the noble gases). However, there's been considerable extraction of the spent fuel by boiling water. Most of Muller's medium volatility fission products (Ba, Sr, Rb, but I'm not sure about La) are going to be readily soluble in water in most chemical forms, and these can be washed out of the spent fuel.

Mueller wrote, "Only medium and low volatility FPsare relocated to the lower head. These FPs generate about 30% of the total decay heat." I am not clear on whether he's saying that only 30% of the heat generation is left or that the fraction of total decay heat that these generate is only 30%, and hence that there's still a lot of heat generation even if these are removed.

 

[Bioengineer01]

Hi dudes, I registered to ask a question of you:

First, check out this video that purportedly shows radioactive steam being released from somewhere under the first floor of reactor 1:



It seems that this steam must be coming up from the basement of reactor 1. Of course, steam means water is boiling.

If the basement is indeed the source of the steam then consider that we know the basement is flooded with millions of gallons of water.

Now, what in this situation could make millions of gallons of water boil?

Could it be that the nuclear fuel has fallen into the basement, achieved criticality, and is now heating all that water?

It could be

 

[westfield]

Wow, I missed this picture up until now.

At 3 minutes after explosion there were two distinct and separate sources of steam release: the containment structure and the SFP.

This all but confirms T-Cups theory about the source of the blast coming from under the containment lid.

But the steam is coming from the SFP and the "tool pool". Containment is in the "gap" between the two steam plumes is it not?

Steam has been observed emanating from the "tool pool" side of the containment structure of Unit #3 since the explosion made that area visible but it is a leap to conclude from that visible steam that containment is a blast source isn't it?

We have images of the concrete blocks separating the reactor void from the "tool pool" and they appear to be un-smashed. Given the building damage there was plenty of lateral force to push the side walls of the building out so much. Explosion source inside containment seems illogical to me given what damage we can see. It leaves a question mark about what caused the lateral forces that popped the RB like a concrete balloon. Hydrogen throughout the entire RB seems much more logical imho. Thats just my 2c of course.

 

[Quim]

I'm responding to westfield #94104
But the steam is coming from the SFP and the "tool pool". Containment is in the "gap" between the two steam plumes is it not?

Steam has been observed emanating from the "tool pool" side of the containment structure of Unit #3 since the explosion made that area visible but it is a leap to conclude from that visible steam that containment is a blast source isn't it?

We have images of the concrete blocks separating the reactor void from the "tool pool" and they appear to be un-smashed. Given the building damage there was plenty of lateral force to push the side walls of the building out so much. Explosion source inside containment seems illogical to me given what damage we can see. It leaves a question mark about what caused the lateral forces that popped the RB like a concrete balloon. Hydrogen throughout the entire RB seems much more logical imho. Thats just my 2c of course.The larger plume of steam is coming from the containment structure - on the east side of the bldg in the center of the building.

The smaller plume is coming from a place south of that - right where we would expect the spent fuel pond to be.The refueling trough (cattle chute) is between the containment structure and the SFP.

I don't know about a "tool pool" do you mean the equipment pool?
That would also be on the east side of the bldg, north of the containment structure.

 

[westfield]

In the photo at the southwest corner of Unit 3 RB it looks like the SBGT pipe might be severed or at least has some debris laying on it. There is no damage to Unit 4 RB yet. If any of you graphics experts can look at this it may be evidence to rule out Hydrogen from Unit 3 causing the explosion or damage in unit 4 through the common stack.

The main duct leading from Unit #3 to the main stack was severed during the Unit #3 explosion. Additionally some days later it appears a concrete wall slab then fell or was deliberately made to fall from the SW upper level of RB#3 and this possibly bent the "elbow" at the severed end when it fell to the shape it is now. The slab is now lying on the ground at the SW corner of RB#3. The main point being that particular pathway was eliminated as soon as RB#3 blew up.

Thats all quite clear however that doesn't eliminate some possible alternate path through other ducting that did remain intact, for instance the ducting running along between the RB's and their respective turbine buildings south down to the central waste treatment facility.

It guess it also doesn't eliminate the possibility that plenty of hydrogen had already made its way to RB#4 prior to RB #3, and that main duct, blowing up.

Edit : Of course the SFP in RB #4 is also a candidate for the hydrogen but NUCENG was only asking about the ducting so that is all I referred to.

 

[Quim]

It guess it also doesn't eliminate the possibility that plenty of hydrogen had already made its way to RB#4 prior to RB #3, and that main duct, blowing up.

The hydrogen for the #4 explosion came from the #4 spent fuel pond as a result of radiolysis.


NUCENG finally came around on that one in post #8496.

The fairy tale about hydrogen from unit 3 weaving its way to #4 is just a Tepco smoke screen.

 

[westfield]

I'm responding to westfield #94104

snip >

I don't know about a "tool pool" do you mean the equipment pool?
That would also be on the east side of the bldg, north of the containment structure.

Yes I do mean the equipment pool where the steam separator and so on are stored during refuelling\maintenance. I'm not saying something in the equipment pool is the source of the steam just that a large consistent amount of steam has been seem appearing to be coming from containment but emanating via the removable concrete modules that separate equipment pool from reactor void. I will try and find the image that shows this reasonably well. What I'm saying is that those removable concrete modules that form the wall appear to be largely undamaged and I'm also suggesting that the steam is coming out from around the containment void and not so much directly from above the void.

But the main point is it's still a stretch to presume that steam escaping from containment is indicative of the source for the explosion.

 

[westfield]

The hydrogen for the #4 explosion came from the #4 spent fuel pond as a result of radiolysis.


NUCENG finally came around on that one in post #8496.

The fairy tale about hydrogen from unit 3 weaving its way to #4 is just a Tepco smoke screen.

NUCENG may well have come to that conclusion in post #8496 but NUCENG also just asked that question about the main duct.

That the SFP in RB #4 is a prime candidate for the hydrogen is obvious however I reasoned that NUCENG was looking for alternatives to SFP scenario because there has been no evidence reported of fuel assembly degradation in SFP of #4.

 

[Jorge Stolfi]

Mueller divides the fission products into high, medium, and low volatility. At Fukushima, a lot of iodine and some cesium probably were boiled off (together with all the noble gases). However, there's been considerable extraction of the spent fuel by boiling water. Most of Muller's medium volatility fission products (Ba, Sr, Rb, but I'm not sure about La) are going to be readily soluble in water in most chemical forms, and these can be washed out of the spent fuel.

However, once the fuel is melted the water cannot penetrate it (perhaps not even make contact with it) and therefore cannot leach out anything directly. Only the volatile elements escape from the molten fuel as vapor and then condense in the surrounding water.

Moreover many compounds of Ba and Sr are insoluble, it is not clear they would be carried out by the water even if it could somehow penetrate the fuel.

Mueller wrote, "Only medium and low volatility FPsare relocated to the lower head. These FPs generate about 30% of the total decay heat." I am not clear on whether he's saying that only 30% of the heat generation is left or that the fraction of total decay heat that these generate is only 30%, and hence that there's still a lot of heat generation even if these are removed.

Not sure what is your question, but my understanding of his scenario is that the radioactive elements that remain in the molten fuel at the bottom of the RPV are such that the decay heat generated inside that mass (in watts) is 30% of the decay heat generated by the full inventory of radioactive elements; i.e. 30% of the decay heat that would be generated by the core at that same moment, if proper cooling had been maintained since shutdown.

 

[Jorge Stolfi]

But the steam is coming from the SFP and the "tool pool".

My undertanding, from all the picures that I have seen, is that the steam from #3 is leaking from the primary containment into the refueling pool. The latter is (probably) still closed by the shield plugs (three concrete discs, each divided into two halves).

Since the #3 explosion, the massive crane (and perhaps other debris) is pressing down on top of those plugs. Thus the steam that is leaking into the refueling pool is now forced to escape sideways, through gaps or cracks around the shield plugs and the gates that separate the refueling pool from the dryer storage pool (aka equipment pool) and from the spent-fuel pool. The two thick white setam plumes seen in the satellite photo seem to match this scenario quite well:

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

Note that the south plume is too narrow to come from the SFP itself; the latter is wider than the refueling pool and extends almost all the way to the south face of the building.

I would guess that the thinner white haze seawards (east) of building #3 is partly steam produced or released by the explosion, partly fine concrete dust that was thrown high up by the explosion, has not yet settled down, and is being carried eastwards by the wind. The whitish "haze" on the opposite (west) side of #3 may be actually a light blanket of concrete dust covering the ground, roofs, and everything else in that area. (Note that the east haze casts a shadow on the ground, while the west "haze" apparently doesn't.)

 

[dh87]

However, once the fuel is melted the water cannot penetrate it (perhaps not even make contact with it) and therefore cannot leach out anything directly. Only the volatile elements escape from the molten fuel as vapor and then condense in the surrounding water.

Moreover many compounds of Ba and Sr are insoluble, it is not clear they would be carried out by the water even if it could somehow penetrate the fuel.

I don't know exactly how to think about the melted fuel, and Mueller points out that the lack of experimental evidence makes a lot of this into conjecture. Inside molten corium, elements and salts can migrate, but I don't know who will go where. The crust could be a nearly homogeneous and impermeable layer, or it could have thinner and thicker places, cracks, nooks and crannies and be sufficiently permeable to allow boiling water to extract things over time. For even money, I'd bet on the latter, but I wouldn't risk much.

BaO and SrO are certainly soluble. There are clearly other possibilities. I'm not sure what the distribution of compounds is. The distribution won't necessarily be the same as in normal spent fuel, because the high temperatures and mixing may give products near thermal equilibrium, a state that might not be reached in solid fuel.

 

[NUCENG]

NUCENG may well have come to that conclusion in post #8496 but NUCENG also just asked that question about the main duct.

That the SFP in RB #4 is a prime candidate for the hydrogen is obvious however I reasoned that NUCENG was looking for alternatives to SFP scenario because there has been no evidence reported of fuel assembly degradation in SFP of #4.

Actually, I was looking for evidence for or against TEPCOs theory of hydrogen going through SBGT ducts and piping from unit 3 to unit 4. If you look back this isn't the first time I asked whether the SBGT piping at the SW corner of RB #3 failed before or after unit 4 was damaged. If we can disprove that theory, by showing that the alleged pathway was already broken, and eliminate zirc water reaction in SFP4 because the fuel remained covered, it only leaves radiolysis in SFP #4 or external damage from a second explosion in Unit 3. It is like my questions about recriticality. Each new piece of evidence needs to be considered honestly even if it may mean a previous theory is weakened or disproved by that evidence. Being wrong is not a bad thing. Being wrong and refusing to accept that possibility is very wrong.

 

[Jorge Stolfi]

Seen on twitter:

MIT Faculty Report on Fukushima: Fukushima Lessons Learned (MIT-NSP-025)
http://mitnse.com/2011/06/03/mit-faculty-report-on-fukushima

Seems a bit dated already, right? AFAIK release estimates are now 20% of Chernobyl not 10%, and the containment of #1 and #3 seem to be leaking too.

 

[cphoenix]

Actually, I was looking for evidence for or against TEPCOs theory of hydrogen going through SBGT ducts and piping from unit 3 to unit 4. If you look back this isn't the first time I asked whether the SBGT piping at the SW corner of RB #3 failed before or after unit 4 was damaged. If we can disprove that theory, by showing that the alleged pathway was already broken, and eliminate zirc water reaction in SFP4 because the fuel remained covered, it only leaves radiolysis in SFP #4 or external damage from a second explosion in Unit 3. It is like my questions about recriticality. Each new piece of evidence needs to be considered honestly even if it may mean a previous theory is weakened or disproved by that evidence. Being wrong is not a bad thing. Being wrong and refusing to accept that possibility is very wrong.

Did someone disprove the steam-explosion hypothesis while I wasn't looking?