Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[jlduh]

I saw table, but I can't find it now with information how long reactors were without water, tahere was: 2,5h for 1&3 and 12,5h for 2 (because they were not able to open some valve) and then additional 50min after one of aftershocks, I think that 12,5h is enought to melt 100% of core ?

Don't know if you read this complete document listed yesterday (169 pages!) but to date this is by far the best documented and complete document on the chronology of the events for each reactor, with precise timing indicated. Have a look at some of the listings pages with times and events that this guy reconstructed, you'll find maybe something useful for your question. BUT, it's worth the reading for anybody on this thread, and also for new members or readers who didn't follow the stuff from scratch.

http://www.galcit.caltech.edu/~jeshep/fukushima/ShepherdFukushima30April2011.pdf

But for the "veterans" of this thead it's also a very good read, very informative on related subjects, and excellent to recap the bits of this complex puzzle (even if the guys is cautionning people that anyway, thuth an reality will only have a chance to be partially or fully understood in several years!)

I cannot put it in attachment to invite you to download it because of its size (11 Mo!)!

 

[jlduh]

A Japanese panel of seismologists knew about the risk of a major tsunami in northeastern Japan before disaster struck on March 11th. The group had put together a report in February and was planning to release it in April".

[...]

Associate Professor Yoshinobu Tsuji at the University of Tokyo's Earthquake Research Institute says the committee needs to further review past disasters to reassess future risks.

http://www3.nhk.or.jp/daily/english/06_27.html

 

[default.user]

I saw table, but I can't find it now with information how long reactors were without water, tahere was: 2,5h for 1&3 and 12,5h for 2 (because they were not able to open some valve) and then additional 50min after one of aftershocks, I think that 12,5h is enought to melt 100% of core ?

On 28 March 1979 at 4:36 clock time closed while work on the condensate polishing plant by a malfunction of the pneumatic control valve in supply line from the condenser to the two main feed pumps in the secondary circuit

german orginal:

Am 28. März 1979 um 4:36 Uhr Ortszeit schloss während Arbeiten an der Kondensatreinigungsanlage durch eine Fehlfunktion der pneumatischen Steuerung ein Ventil in der Speiseleitung vom Kondensator zu den beiden Hauptspeisepumpen I am sekundären Kreislauf

Since the beginning of the incident 165 minutes had passed when radioactively contaminated water reached the sensors. At this time, the radioactivity in the primary cooling circuit 300 times higher than expected: The meltdown was in full swing.

The operators in the control room was not aware for a long time, as little water as the primary cooling circuit still contained. About three and a half hours after the incident began to recognize the scope hurrying experts - new water was pumped into the primary circuit. Later it was found that fused together for roughly half of the inventory and a supercritical state was narrowly avoided.

german orginal:

Seit Beginn des Störfalls waren 165 Minuten vergangen, als radioaktiv kontaminiertes Wasser die Sensoren erreichte. Zu diesem Zeitpunkt war die Radioaktivität I am primären Kühlkreislauf 300-mal höher als erwartet: Die Kernschmelze war in vollem Gang.

Den Bedienern I am Kontrollraum war lange Zeit nicht bewusst, wie wenig Wasser der primäre Kühlkreislauf noch enthielt. Ungefähr dreieinhalb Stunden nach Beginn des Störfalls begannen die herbeigeeilten Fachleute die Tragweite zu erkennen – neues Wasser wurde in den Primärkreis gepumpt. Später wurde festgestellt, dass bereits etwa die Hälfte des Inventars zusammengeschmolzen und ein überkritischer Zustand nur knapp vermieden wurde.

It had been almost 16 hours, when the pumps were turned on again in the primary circuit and the core temperature began to fall.

german orginal:

Es waren fast 16 Stunden vergangen, als die Pumpen I am Primärkreislauf wieder eingeschaltet wurden und die Kerntemperatur zu fallen begann

http://de.wikipedia.org/wiki/Kernkraftwerk_Three_Mile_Island#Unfallhergang

http://en.wikipedia.org/wiki/Three_Mile_Island_accident

http://en.wikipedia.org/wiki/Fukushima_Daiichi_Nuclear_Power_Plant#Reactor_data

Will certainly have to consider the difference in the types of reactor.
But we can see that could melt within 10 to 16 hours the entire inventory.

It may help you.

kind regards

 

[elektrownik]

Thanks !, I was searching for this, also this 169 pages presentation from few post up give 17h without water, I think that it is enought to full melt of core, unit 1 was without cooling only 2,5h and they give 70% core damage for it, so if #2 was 17h without cooling...

 

[Samy24]

Maybe "they" have learned the lession?

http://www3.nhk.or.jp/daily/english/06_27.html"
http://www3.nhk.or.jp/daily/english/06_31.html"

 

[Samy24]

Thanks !, I was searching for this, also this 169 pages presentation from few post up give 17h without water, I think that it is enought to full melt of core, unit 1 was without cooling only 2,5h and they give 70% core damage for it, so if #2 was 17h without cooling...

The first time I read this document I believed the cores could have been melted completely.
Time without water and CAMS radiation readings point straight to this.
(I'm not a nuclear engineer.)
http://www-pub.iaea.org/MTCD/publications/PDF/te_955_prn.pdf"

 

[Rive]

... so if #2 was 17h without cooling...

Be careful, TMI2 was on full power when the water stopped. Fukushima was ~1 hour after SCRAM when the diesel lost. During that one hour the initial ~10% remanent thermal power was down to ~2%. And even after the diesel gone there was some partial cooling for some time.

Ps.: and fuel damage is not meltdown. It's far from that.

 

[jlduh]

Thanks !, I was searching for this, also this 169 pages presentation from few post up give 17h without water, I think that it is enought to full melt of core, unit 1 was without cooling only 2,5h and they give 70% core damage for it, so if #2 was 17h without cooling...

By the way Elektrownik did you manage to extract the time without water at N°3?

If time without water was 2,5h at N°1 and 17h at N°2, how can it be that Tepco is giving a much higher percentage of damage on N°1 (70%) than on the two others? I know from where they are getting these numbers (froms CAMS right?) but i mean, how can it be correlated with these times without water? Of course the height of exposed fuel rods is also a factor (without water means without any new water injected to compensate for steam conversion) but still this is strange, no?

Concerning the "damaged versus melted" difference, i understand it of course, but still, if it stays uncovered for a long time (and we know that, if the readings of water level inside the cores are working, which is NOT sure i admit, it stayed like that for weeks now at level like -2000mm below top fuel level for example at N°3), it is going either to melt, or to break (before melting) and fell into bottom water at some point. But if it breaks and fell but is blocked by other debris or bent stuff inside the core before reaching water level, the pellets are going to melt, don't you think?

So anyway, after a so long time (weeks), everything that is (or was!) higher than the water level has been "damaged" and relocated somewhere at a lower level inside the RPV, right? Damaged means either broken and relocated before melted, or broken, melted and relocated further down.

Am I wrong?

 

[yakiniku]

Don't know if you read this complete document listed yesterday (169 pages!) but to date this is by far the best documented and complete document on the chronology of the events for each reactor, with precise timing indicated.

Great link. I have only just started making my way through it. Thought I would add some anecdotal information that the WSJ wrote regarding pressure limits:

"Containment vessels can withstand higher pressures, some studies have indicated. Among these are studies conducted in the 1990s by Japanese operators and equipment manufacturers, in preparation for Japan's first set of severe-accident protocols, that say such vessels can withstand twice the design pressure. Many Japanese operators have adopted this as their benchmark for releasing contaminated air.

Tepco spokesman Yoshikazu Nagai confirmed that if there is a risk of releasing radiation, the company doesn't vent until pressure hits roughly twice the design limit. "Venting is a last resort," Mr. Nagai said.

General Electric Co., the designer of the vessel at Fukushima Daiichi, said it is unaware of any such Japanese studies or venting protocols."

http://online.wsj.com/article/SB10001424052748703922504576273234110896182.html

Edit: This is regarding the pressure limits mentioned on page 10 in the presentation

 

[Dmytry]

Don't forget to double-check all third party facts or compilations.

I've seen several articles that simply asserted gross untruths. This for example:
http://atomicinsights.com/2011/04/fukushima-nuclear-accident-exceptional-summary-by-murray-e-miles.html
"Something nearly miraculous occurred to prevent units 1, 2, and 3 from early catastrophic failure. About eight hours after the earthquake Tokyo Electric Company made the decision to pump seawater into the reactors and reactor containment buildings of units 1, 2, 3, and 4."
which is patently false; the quake did strike at march 11th, 14:46 ; according to NISA, http://www.nisa.meti.go.jp/english/files/en20110317-1.pdf
the water injection has started at:
unit 1: march 13th, 11:55 (seawater) (or quake+45 hours 10 minutes)
unit 2: march 13th, 14:00 (seawater)
unit 3: march 13th, 11:55 (freshwater, followed by seawater shortly thereafter)
unit 4: no fuel in reactor

On topic of venting: I'm pretty sure that's wrong. You can't vent safely at beyond the design pressure. Venting at such pressure is probably how they managed to explode 3 reactors out of 3 (the #2 less impressively though than the other two). Overpressure beyond limit is known to cause leakage of the vented gasses (steam, hydrogen) into the building, hence the explosions; in #3 there is a lot of reasons to suspect the lid of the containment vessel was lifted a bit briefly, leading to explosive venting and massive mushroom cloud 'explosion' in the hollywood style.

 

[jpquantin]

The reaction is 2 H₂O + Zr --> ZrO₂ + 4 H₂. For your high end estimate, making 1e+06g of H₂ requires (1e+06g/2g/mole)/4*91g/mole = 11e+06g Zr. This seems like a lot of Zr available for oxidation since only the surface Zr is immediately available, if I understand the chemistry correctly. The low end is probably too low because the escaping hydrogen will fall below 4% and won't explode, whereas there were explosions in the escaping material.

Could you tell us how much energy does one reaction would release ? Thanks.

 

[fluutekies]

Could you tell us how much energy does one reaction would release ? Thanks.

Zr + 2H₂O --> ZrO₂ + 2H₂ + 14.6*10⁶ J/kg Zr

Source: http://www.galcit.caltech.edu/~jeshep/fukushima/ShepherdFukushima30April2011.pdf page 62

BTW: Great source!

Edit: another source http://oa.upm.es/718/1/Miguel_Angel_Jimenez_Garcia.pdf dH = 576 kJ/mol Zr

My Spanish is not good, but it seems that this PhD thesis is worth reading ...

 

[kerkko]

Something seems weard here.
Lower floors must have had an implosion instead of the explosion.
From 30 sec on at the video. I mean there is no way that the powder you see in video could have stayed there if there was that strong explosion, it would have blown out that debris.

 

[elektrownik]

From data which I saw unit 3 was 2,5h without water (#1 also 2,5h). In case of #3 explosion I will stay with my opinion: hydrogen explosion in SFP and then explosion in core or drywell, if you look on explosion video you will see that the second big explosion is from core location, not from SFP...

 

[kerkko]

Something seems weard here.
Lower floors must have had an implosion instead of the explosion.
From 30 sec on at the video. I mean there is no way that the powder you see in video could have stayed there if there was that strong explosion, it would have blown out that debris.

Im not an physics expert or anything, my field of work is demolitions, but i have seen enough to tell from that video that the explosion in plant 3 was not normal..
I think that the top of the reactor blew up, sucking air to lower levels causing an implosion at the lower levels, creating a pipelike effect.

 

[AntonL]

Fukushima radiation exported to the Netherlands,

http://www.channelnewsasia.com/stories/afp_world/view/1127251/1/.html

"Traces of radioactivity were detected on the exterior of the container, but none in the cargo itself," customs spokeswoman Gera van Weenum told AFP, adding the levels exceeded the maximum authorised of four becquerel, but were not dangerous.

"There were spots of radioactivity of up to 33 becquerel, but the average was six becquerel," said the spokeswoman.

 

[unlurk]

my opinion: hydrogen explosion in SFP and then explosion in core or drywell

TCups made a pretty good case for the explosion to have originated above the drywell containment and traveled through the re-fueling trough and then to the FP.

In any event, hydrogen is lighter than air, it would have accumulated high in the building had it come from the FP. Unit 4 is an example of that chain of events.

 

[Bandit127]

Regarding Unit 3 imploding.

If my understanding of explosions is right, a chemical explosion is a rapid combustion reaction that turns (typically) solids or liquids into gasses and creates heat. The rapid expansion of the gasses creates a shockwave that can be subsonic (I think this is Gunderson's 'deflagration') or supersonic ('detonation').

Supersonic detonation occurs when the reaction is perpetuated by the shockwave compressing chemicals to the point that they spontaniously combust.

In a normal 'explosion', we would expect the solids/liquids to expand in volume by orders of magnitude as they turn into gasses. (I only know liquid nitrogen off the top of my head, but that expands in volume by about 670 times at 1 bar).

So a normal explosion will have gas that has been expanded behind the shockwave from solids/liquids that provided the 'fuel' for the explosion.

However, a hydrogen/oxygen explosion starts out as a gas. The shockwave will propogate from the ignition point as a normal explosion would, but the reaction leaves H₂O.

My physics teacher reckoned that the product of a hydrogen/oxygen burn in our classroom (he was a great Physics teacher) would be 1cc of water. I.e. a pretty good vacuum - if it condenses.

So, perhaps it is natural that we should see some signs of an implosion as the volume that was occupied by all the hydrogen and oxygen before the explosion has effectively shrunk to nearly zero.

 

[kerkko]

I think they didnt vent out the steam from reactor 3, or they could not.
And all the hydrogen builded up inside the core, creating an one big furnace/cannon.
This would explain the debris and the iron bars pulled inwards.
The core blew its top and sucked in the air like one big engine?

http://www.youtube.com/watch?v=oPevraef4gI&feature=fvwrel
Pulsejet Engine

 

[unlurk]

Regarding Unit 3 imploding.

I suspect you may have explained why the upper panels of unit four are tilted inward.

 

[AntonL]

Regarding Unit 3 imploding.
...

My physics teacher reckoned that the product of a hydrogen/oxygen burn in our classroom (he was a great Physics teacher) would be 1cc of water. I.e. a pretty good vacuum - if it condenses.

So, perhaps it is natural that we should see some signs of an implosion as the volume that was occupied by all the hydrogen and oxygen before the explosion has effectively shrunk to nearly zero.

Very correct what your physics teacher is saying however that is only 20 of the volume that gets removed, below I posted in March before the implosion idea was deducted from the videos. But also study the referenced document that shows the negative pressure after a Hydrogen explosion

To 1) I can only think that a hydrogen blast is followed by an implosion as all the air that has been displaced gushes back into the vacuum created. Maybe someone will want to correct me on this. Thus depending on the blast dynamics the north wall could have been sucked back into the building.

That a hydrogen explosion is followed by an implosion I have speculated in https://www.physicsforums.com/showpost.php?p=3199497&postcount=641"

I now have found the proof in this document http://www.gexcon.com/doc//PDF files/Middha_Hansen_CFD_09.pdf see pressure graphs page 3 of 8

 

[Rive]

I mean there is no way that the powder you see in video could have stayed there if there was that strong explosion, it would have blown out that debris.

There is a video available about the explosion of U3. You can see the debris falling after the explosion. So it did not had to stay, it could just fall black there.

 

[kerkko]

There is a video available about the explosion of U3. You can see the debris falling after the explosion. So it did not had to stay, it could just fall black there.

You mean this?


I mean if it was only hydrogen explosion at the top floor, then the debris should have been flung outwards. I am only trying to point out that in my view the upwards explosion and the stuff in lower levels seems very weard. To pull those iron bars inwards takes some serious forces.

 

[Ms Music]

Do you have a link to the Japanese language site?

The hydrogen blasts are probably going to show up below 2 on the Richter scale.

I haven't read past this post, so I have no idea if anyone else gave suggestions. If my memory serves me right, it appeared to me the JMA website is the biggest earthquake network. http://www.jma.go.jp/jma/en/Activities/earthquake.html But I can't remember that I was able to navigate my way anywhere useful for finding the past two weeks of data? This is the Japanese site that I was unable to read, but may have useful data: http://www.hinet.bosai.go.jp/

Today, in doing a google search of "Japan seismic network" (to find where I went) I also found this link, which looks like they have recently posted data that may be worth looking into. http://www.fnet.bosai.go.jp/top.php?LANG=en Last time I searched, I believe I did an advanced search, limiting to .jp websites, that may help you in your search.

I think why I was unsuccessful was that I had spent too much time sifting through data I had easy access to (USGS which shows 4.0 and above), and ran out of time to search for Japan networks.

Best of luck to you. Sorry my links aren't "proper", it appears pop ups are blocked again on my internet, and didn't want to mess with settings. I would offer my assistance, but am out of time at work (lunch break is over), and I don't get on the computer at home on weekends. But I will do what I can if you need more. If for some reason you are interested, I still have the 4.0 and above data.

 

[NUCENG]

By the way Elektrownik did you manage to extract the time without water at N°3?

If time without water was 2,5h at N°1 and 17h at N°2, how can it be that Tepco is giving a much higher percentage of damage on N°1 (70%) than on the two others? I know from where they are getting these numbers (froms CAMS right?) but i mean, how can it be correlated with these times without water? Of course the height of exposed fuel rods is also a factor (without water means without any new water injected to compensate for steam conversion) but still this is strange, no?

Concerning the "damaged versus melted" difference, i understand it of course, but still, if it stays uncovered for a long time (and we know that, if the readings of water level inside the cores are working, which is NOT sure i admit, it stayed like that for weeks now at level like -2000mm below top fuel level for example at N°3), it is going either to melt, or to break (before melting) and fell into bottom water at some point. But if it breaks and fell but is blocked by other debris or bent stuff inside the core before reaching water level, the pellets are going to melt, don't you think?

So anyway, after a so long time (weeks), everything that is (or was!) higher than the water level has been "damaged" and relocated somewhere at a lower level inside the RPV, right? Damaged means either broken and relocated before melted, or broken, melted and relocated further down.

Am I wrong?

Remember that Unit 1 had only the isolation condenser once power was lost. This condenser took reactor steam through a heat exchanger in a pool of water where it was condensed and flowed back to the reactor. The backup in an early design BWR 3 is pumping water into the reactoor with the feedwater system. That requires electricity. Later design BWR-3s added the RCIC system which operates on reactor steam and DC power.

At Unit 1 once the isolation condenser pool boiled dry it lost all cooling AND all makeup. Thus it was the first to experience core damage and hydrogen buildup. The venting of containment was delayed until the containment was more than double its design pressure so it was likely leaking before the hydrogen finally exploded. The explosion blew out the walls and roof on the refueling floor which may mean most of the leakage was from the containment cap which reportedly may begin leaking as low as 27 psig. If the explosion did not propagate to the drywell it may explain why the unit 1 containment is still holding some pressure and why the operators are working to reinert tha unit 1 containment with nitrogen. There could still be a lot of hydrogen inside.

This is my speculation on why unit 1 was the first and worst damage and where it may be today.

 

[mscharisma]

correct, unless electronic zoom or electronic selection of a part of the complete frame is transmitted

EDIT: correction, I took another frame of the TBS/JNN feed and drew some lines
looks OK to me
[PLAIN]http://k.min.us/inqMBW.JPG[/QUOTE]

Thank you. Appreciated!

 

[jim hardy]

Re the appearance of a vacuum

indeed post on previous page has the idea.

Look up terms "bernoulli" and "venturi"

if the explosion indeed ducted a lot of gas UPWARD at high speed it'd suck in stuff from adjacent the edge of the duct. That's how a carbureter works - a stream of fluid in motion is at lower pressure than when it's at rest. so that awful jet of black stuff headed straight up late in the explosion made a vacuum adjacent to itself.

http://www.youtube.com/watch?v=4czczYnuM_w&feature=related

 

[Borek]

However, a hydrogen/oxygen explosion starts out as a gas. The shockwave will propogate from the ignition point as a normal explosion would, but the reaction leaves H₂O.

My physics teacher reckoned that the product of a hydrogen/oxygen burn in our classroom (he was a great Physics teacher) would be 1cc of water. I.e. a pretty good vacuum - if it condenses.

So, perhaps it is natural that we should see some signs of an implosion as the volume that was occupied by all the hydrogen and oxygen before the explosion has effectively shrunk to nearly zero.

For gaseous water to condense it has to be cooled down. I doubt it had a chance to get below 100 deg C in the explosion time scale.

 

[MiceAndMen]

TCups made a pretty good case for the explosion to have originated above the drywell containment and traveled through the re-fueling trough and then to the FP.

I think his hypothesis involved the explosion initiating inside the drywell, not above it. If so, where did the oxygen come from for that initial explosion?

 

[NUCENG]

Could you tell us how much energy does one reaction would release ? Thanks.

The fuel design of a nuclear reactor is aimed at providing a maximum surface area for heat transfer. Do the math and you will be surprised how large the number is. The Unit 1 had 400 bundles if I remember correctly and 584 in units 2, and 3. If they were 9x9 fuel there are 74 fuel rods and 2 water rods per assembly. OD is about 11 mm with clad thickness of 0.7 mm. You can use a legth of 12 feet because you will need to estimate how much is uncovered. Finally once the clad is perforated it also exposes the inner surface to oxidation and steam.

 

[Rive]

I mean if it was only hydrogen explosion at the top floor, then the debris should have been flung outwards.

Take a look at the explosion of U1 and the current situation around the unit. THAT was a clean hydrogen explosion - and at the end the roof were landed on the top of the service floor, and only the walls were flung outwards.

I am only trying to point out that in my view the upwards explosion and the stuff in lower levels seems very weard. To pull those iron bars inwards takes some serious forces.

And you are absolutely right about that. IMHO.

 

[jim hardy]

I like to put things into familiar terms that one can "feel".

Check my arithmetic and see if that kJ/mole doesn't translate to about 2500 BTU per pound of zirconium.

So that piece Arnie burned with his blowtorch would release about the same heat as burning a piece of your barbecue charcoal 1/4 as large, maybe half a briquette...


that's a fair amount of heat. You know what coal dust explosions do to a coal mine...

old jim

 

[unlurk]

I think his hypothesis involved the explosion initiating inside the drywell, not above it. If so, where did the oxygen come from for that initial explosion?

I took his hypothesis to indicate that the source of the hydrogen from the explosion was from the drywell. I don't believe he was specific in stating where the exact point of ignition was. In my view, the Oxygen would have existed just above the drywell seal.

 

[unlurk]

This is the Japanese site that I was unable to read, but may have useful data: http://www.hinet.bosai.go.jp/

But I will do what I can if you need more.

I applied for registration at that site (my Google translator does a pretty good job.)

But they indicate that their data begins at 2.5 and what we are looking for may be a lower energy than that.

Also their registration process had me OK to this:
"Users are strictly prohibited to create and re-distribute any duplication."

The use of the words "strictly" and "any" would seem to preclude even posting their info here.

What we really need is a geologist type who accesses this kind of data in a normal day's work.

 

[Bodge]

it can not...
according to the graphs here: http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110427e19.pdf
130Sv/h would mean a core damage rate of above 100%

but as the readings of A and B differ by magnitudes, i would assume, that the readings are almost meaningless.
as long as we don't know, what exactly these monitors *see*, we simply don't know what these readings mean.

How about transient criticalities creating new decay products?