Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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?

 

[elektrownik]

I want ask about something: what about control rods ? I understand that when reactor cooling stops, temperature is increasing to the point when fuel rods are melting, and entire core is melting, but we know that water is moderator, so it slow down neutrons and then there is chain reaction, so no water no chain reaction, but no water = no cooling, so because this there are boron control rods, when they are inserted into core chain reaction stops, and core can be cooled with water, but what after core melt ? I understand that, size, number, place of control rods are very important. When core is melting control rods are also, so their parameters are changing. So what when we have melted core, I see 2 options: melted core without water and with damaged control rods, can melted core be moderator for itself ? If water slow down neutrons melted uranium also should ? And 2nd option, like 1 but with water, if melted core is not moderator for itself then what when water hit melted core with damaged control rods ? It will slow down neutrons ? More water = more chain reaction ?

 

[MadderDoc]

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.

I think in the early phases of the event, during which time it must be that some see signs of an implosion, the water would likely still be mainly as vapor. The _first_ we see of the event is something shooting out from the building, which of course is the opposite of an implosion. But a fraction of a second later we get the evolution of the rising cloud, and that by its nature does produce a suction effect.

During the first few seconds of the evolution of the cloud over unit 3, it is rising as a parcel of extremely unstable air, with a speed of about 70 m/s or more, comparable to what we see in supercells. A strong updraft of air will naturally produce strong horizontal movement of air at its base, going towards the center of the updraft.

In the video we clearly see this effect shortly after the appearance of the rising cloud over the building: the dust produced by the blast that is spreading around the building, suddenly appears to be sucked back into it.

 

[Bandit127]

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.

It doesn't need to get below 100°C.

For example, the top entry on http://www.simetric.co.uk/si_steam.htm" , steam to water volume is ~1603:1, so even at 120 Bar (and assuming a stoichiohometric atmosphere - highly unlikey I know) the resulting pressure would be 0.07 Bar(a) or -0.94 Bar(g).

I don't have any idea what the temperatures and pressures were, but I think it is likely that a hydrogen explosion could pull at least a partial vacuum behind it.

 

[Rive]

... what when water hit melted core with damaged control rods ? It will slow down neutrons ? More water = more chain reaction ?

There are too much hits for 'reflooding recriticality' documents to link them here...

 

[Borek]

It doesn't need to get below 100°C.

Yep, in high pressures.

I don't have any idea what the temperatures and pressures were, but I think it is likely that a hydrogen explosion could pull at least a partial vacuum behind it.

I don't know details as well, but my feeling is that during explosion temperature is high enough to not allow condensation, and after the explosion (that is, when the gas expands and walls are destroyed) pressure inside is already down to atmospheric, so you need to get below 100 deg C. And the cooling process will be way too slow to create implosion.

Note: I am not stating there was no implosion, I am stating I don't believe condensation was behind.

 

[~kujala~]

The gate broken theory is interesting, but it seems to contradict with other observations.

I was satisfied with your explanations.

One additional check one could do is to put the thermal image of the unit 4 on top of this picture, in same direction and proportion:

https://www.physicsforums.com/attachment.php?attachmentid=35237&d=1304674683

If the gate is broken there should be a larger area of warm water than with gate functioning and this larger area could perhaps be seen in the thermal image.

I think the thermal image of the unit 4 has been analyzed at some point, but perhaps not on top of the above picture.

One other notice: TEPCO's thinking has perhaps gone the same way and that's why they don't feel the need to check inside unit 4 any more. As far as I have understood TEPCO has only checked the premises below SFP 4 to see if SFP is leaking:

The company checked the reactor facilities, suspecting water might be leaking from the pool, but cannot confirm water leakage into the bottom structures of the reactor building.

http://www.yomiuri.co.jp/dy/national/T110428006723.htm

I think if they still suspected that SFP is leaking to RPV they would also have to check RPV for leaks and it would require some additional checks. So my understanding is that they have only checked the reactor building for SFP leaks, so far, which is a different thing than to check the reactor building for SFP + RPV leaks. Or is it?

 

[Bandit127]

Yep, in high pressures.



I don't know details as well, but my feeling is that during explosion temperature is high enough to not allow condensation, and after the explosion (that is, when the gas expands and walls are destroyed) pressure inside is already down to atmospheric, so you need to get below 100 deg C. And the cooling process will be way too slow to create implosion.

Note: I am not stating there was no implosion, I am stating I don't believe condensation was behind.

I respect your opinion. I will park my hypothesis in lieu of further data and hope we can continue this discussion in the unlikely event that we ever get it.

 

[bytepirate]

There are too much hits for 'reflooding recriticality' documents to link them here...

slightly offtopic maybe, but a very useful google feature:

you can search in a timeframe. e.g searching all documents indexed before the tsunami, add 'daterange:0-2455631' to your query (without the quotes)

details here: http://jwebnet.net/advancedgooglesearch.html#advDateRange

 

[bytepirate]

How about transient criticalities creating new decay products?

IF you trust the readings of 130 Sv/h that could be an explanation.

what i was trying to say in my original post was: a core melt of 100% might be possible, a core melt of *more than* 100% is certainly not.

 

[TCups]

REGARDING ALLEGED IMPLOSION AT BUILDING 3

Let me say it unambiguously. I do not think implosion occurred at Bldg 3 (or elsewhere). All photographic evidence I have seen (and I have studied it in great detail) suggests violent explosion and violent explosion only. The photographic evidence shows that the blow out panels were blasted outward with great force, the roof was blown upward and off the building, and something heavy fell on the northwest corner of Bldg. 3 after the initial explosion. I have seen no compelling photographic evidence to the contrary.

I do not think that either chemical implosion or negative pressure from Venturi effect or any other negative pressure theory accounts for any of the visible damage I have seen. I do not believe that the video of the explosion of Unit 3 shows implosion.

The one possible effect of negative pressure effect I have speculated on is this: that negative pressure at and around the epicenter of the Bldg. 3 explosion might have had some effect on the distribution of hydrogen gas leaked into Bldg. 4 prior to the explosion at Bldg. 4, specifically, the potential of pulling more hydrogen into the lower portion of Bldg 4 prior to its explosion.

Bldg. 4 remains the enigma of the explosions, IMO. If hydrogen was the fuel for the explosion, how did it get into the lower portions of Bldg 4?