Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[fusefiz]

IR for reactor 3 -- I believe this indicates 62 C over the fuel pool, 128 C on the other side of the reactor head:
| http://www.welt.de/multimedia/archive/01340/Fukushima_hoch_DW__1340857z.jpg

Interesting picture here -- I do not believe the crane and cars are at reactor ground level, but rather on the embankment behind the reactors:
| http://tvde.web.infoseek.co.jp/cgi-bin/jlab-dat/s/795434.jpg

Detailed ground level radioactivity readings (I do not know where this picture comes from nor its reliability, but it appears to be genuine):
| http://static.ow.ly/photos/original/9ooW.jpg
The highest readings are just to the west and north of reactor 3. These reading may be consistent with the French agency's conclusion (and, I believe, an early conjecture here in this thread) that the protection shield over the reactor has disappeared. Gamma ray radiation could then be reflected back down around the reactor building by the remaining beams and detritus (as well as simply backscattered by the atmosphere).
| http://www.irsn.fr/FR/Actualites_pr...Seisme-Japon_Point-situation-20032011-06h.pdf
The annotated photo in this French IRSN report interprets the north side of reactor 3 as being the ruins of the destroyed service deck as well as the floor beneath the service deck.

Here is some preliminary evidence from the Test Ban Treaty Organisation that there has been no major destruction of the zirconium cladding:
| http://www.nature.com/news/2011/110317/full/news.2011.168.html
" ... the data show high amounts of volatile radioactive isotopes, such as iodine and caesium, as well the noble gas xenon. But so far, the data show no high levels of the less volatile elements such as zirconium and barium that would signal that a large meltdown had taken place ... "

 

[TCups]

TCups,

To the best of my knowledge as of Sunday evening no, he said it would be some time before he may travel there. We could use his expertise since it revolves around the aging process of the fuel and fuel mixtures used. I am sure if he is about he will pop in and contribute.

Just to lighten the mood somewhat, don't you guys, TCups, AtomicWombat, etc... ever sleep ! Sometimes to step away for a bit allows your brain to mull things over and you come back with fresh insight. It happens for me once in awhile, mostly in the shower in the early am.

When this whole affair wraps up, hopefully positively, I hope you guys stick around and contribute your life skills, it has been interesting to watch to say the least.

Rhody...

(deep sigh) - I work all day in front of 6 large computer screens and 3 computers (one is a Mac) interpreting images of women's breasts. Go figure. A physician by occupation, I gave up getting sleep on any regular basis years ago. Looking at exploding reactors is a pleasant diversion, weird as that seems. And I enjoy the exchange here. I have learned a lot.

 

[turbo]

Astro is headed to the West Coast office of his employer. He said during chat that his presence here would by sporadic for a while. And yes, he does want to be able to travel to Japan as a consultant/troubleshooter.

 

[AtomicWombat]

Some BOTE calculations of the pressure impulse required to lift the concrete shield plug 500 metres into the air (assuming this is what occurred in the reactor 3 explosion).

Width of plu ~ 10 metres.
Thickness ~ 2 m
Density ~ 2.5 tonnes/m^3
Weight = pi*5^2*2 ~ 400 tonnes
Area ~ pi*5^2 = 80 m^2

Energy required to lift 400 t to 500 metres = mgh = 400000*10*500 = 2*10^9 J = 2000 MJ

impulse is force*delta_t = 2000 MJ assuming no loss
Pressure Impulse = Impulse/area => 2000*10^6/80 = 2.5*10^7 = 25 *10^6 Pa = 25 MPa = 250*delta_t atm.Assume delta_t = 1 sec, Pressure is 250 atm.

Primary containment is rated to about 500 kPa (5 atm) - will present no barrier to this pressure impulse.

Reactor pressure vessel has a design pressure of 1250 psig ~ 85 atm. Assuming 100% overdesign this is 170 atm.

http://img863.imageshack.us/img863/3206/reactor.jpg

The pressure transient required to blast the concrete plug to 500 metres is of the order required to rupture the reactor - assuming the reactor was not breached by a melt-down in the first place.

 

[TCups]

Some BOTE calculations of the pressure impulse required to lift the concrete shield plug 500 metres into the air (assuming this is what occurred in the reactor 3 explosion).

The pressure transient required to blast the concrete plug to 500 metres is of the order required to rupture the reactor - assuming the reactor was not breached by a melt-down in the first place.

Maybe not! Sometimes if you just keep looking, you will see the obvious. . .

1) the north wall did not collapse inward. The vertical and diagonal overlay pattern of the roof beams is the normal structure of the roof beams. Compare the intact beam structure of Unit 4 to the undamaged remaining portions of Unit 3.

2) The central portion of Unit 3's roof beams are intact, and, I believe, collapsed downward after the initial blast blew out the south wall and the crane blew back through the north wall. This hint actually came from the French-annotated picture, above, fuzefiz's post. The heavy overhead crane structure was blasted out the back wall, falling on and heavily damaging a portion of the building below (arrow)

3) Implication: the plug is likely still atop the core containment, roughly in the center third of the damaged Unit 3 bldg. The blast came outward through the SFP gate, breeching the side of the containment, then, upward, out of the SFP (circle).

4) The sidewise blast peeled back a part of the corner of Unit 4.

Again, this:

 

[Bez999]

"The pressure transient required to blast the concrete plug to 500 metres is of the order required to rupture the reactor - assuming the reactor was not breached by a melt-down in the first place."

Quite apart from your calculations and the correctness of the assumptions, the effect is either or, not both. The energy necessary to blast the "cork" would rupture and destroy the containment first, thereby dispersing the energy that would have been required to shoot the lid in the air.

If there were dimensions to calculate the volume of the containment it would be possible to see whether that volume (given the pressure and likely mixture characteristics) would in fact contain enough explosive energy.

My guess is that the theory of path of least resistance through the gate to the SFP is the most likely scenario.

 

[Bez999]

"Implication: the plug is likely still atop the core containment. The blast came outward through the SFP gate, breeching the side of the containment, then, upward, out of the SFP."

Only problem is that that doesn't mash with the actual lay out, where the SFP is on the other side of the building (South side). What appears to have been blasted away in that photograph would be the equipment pool, which in the schematics appears much less heavy duty than the SFP anyway. (Not surprising as it is less deep, smaller and does not contain tons of fuel rods in addition to water. The schematics are not clear about there being a gate between the equipment pool and the containment head, probably not as what goes in the equipment pool is not as active as fuel assemblies.

 

[AtomicWombat]

UCS details on SFPs:

http://allthingsnuclear.org/post/4008511524/more-on-spent-fuel-pools-at-fukushima"

 

[AtomicWombat]

"The pressure transient required to blast the concrete plug to 500 metres is of the order required to rupture the reactor - assuming the reactor was not breached by a melt-down in the first place."

Quite apart from your calculations and the correctness of the assumptions, the effect is either or, not both. The energy necessary to blast the "cork" would rupture and destroy the containment first, thereby dispersing the energy that would have been required to shoot the lid in the air.

Well, no. A pressure vessel in the primary containment would have to withstand a pressure transient that blew that containment apart.

My guess is that the theory of path of least resistance through the gate to the SFP is the most likely scenario.

It is not clear to me that the gate to the SFP forms part of the primary containment wall. It seems to be the drywell head and removable shield plugs form a barrier to the SFP when the reactor is operating. These are removed during refueling.

 

[AtomicWombat]

UCS details on SFPs:

http://allthingsnuclear.org/post/4008511524/more-on-spent-fuel-pools-at-fukushima"

According to this table the heat generation from unit 4 SFP is 1,600 * 1000 kcal/hr.

This is 1,600 * 1000 *4.2/3600 kW = 1867 kW ~ 2 MW.

My earlier estimate of 8 MW was a factor of 4 too high:
http://74.86.200.109/showpost.php?p=3192958&postcount=302"

 

[TCups]

It looks like I just spent about 90 minutes reviewing just under 10 minutes of video, and capturing 75 still frames from the video.



I challenge everyone here, now knowing the additional information that has been added and the hypotheses being discussed of:
1) a blow out of the plug atop containment through the roof,
2) a blow out of the transfer gate aside the top of the containment through the SFP, or
3) some other explosion scenario

to review that video very, very carefully. Too late to discuss more this evening. Want to see inside the SFP? There was a very good reason the helicopter flew through the smoke and steam.

I am crashing now. Maybe more discussion tomorrow -- I meal later today. . .

 

[TCups]

PS: SEISMOGRAPH?

Can one of you talented internet users check the seismography records and see what the blast at Unit 3 registered on the Richter scale, please? Thanks.

 

[TCups]

"Implication: the plug is likely still atop the core containment. The blast came outward through the SFP gate, breeching the side of the containment, then, upward, out of the SFP."

Only problem is that that doesn't mash with the actual lay out, where the SFP is on the other side of the building (South side). What appears to have been blasted away in that photograph would be the equipment pool, which in the schematics appears much less heavy duty than the SFP anyway. (Not surprising as it is less deep, smaller and does not contain tons of fuel rods in addition to water. The schematics are not clear about there being a gate between the equipment pool and the containment head, probably not as what goes in the equipment pool is not as active as fuel assemblies.

Show me the reference and the floor plan if you have it, please. Also maybe a picture of where the water is being sprayed on Unit 3 -- presumably they are aiming at the SPF. Thanks.

 

[Bez999]

"Well, no. A pressure vessel in the primary containment would have to withstand a pressure transient that blew that containment apart."

I was referring to the "secondary" containment of course (the dry well), also in relation to the gate. It is obvious from all diagrams that there is no physical connection between the reactor vessel and the SFP.

 

[Arcer]

Do new fuel rods go straight into the reactor after inspection.

 

[AtomicWombat]

"Well, no. A pressure vessel in the primary containment would have to withstand a pressure transient that blew that containment apart."

I was referring to the "secondary" containment of course (the dry well), also in relation to the gate. It is obvious from all diagrams that there is no physical connection between the reactor vessel and the SFP.

This threw me for a while - http://www.oecd-nea.org/press/2011/BWR-basics_Fukushima.pdf"

The primary containment is the flask like concrete structure with a steel cap. It includes the drywell and wetwell. The secondary containment is essentially the reactor building. The reactor is a separate vessel suspended within the primary containment.

 

[Arcer]

I suppose it's possible that the plug to 3 had been temporarily removed (fully or partially over the opening) before the explosion for some reason. Possibly to help with the cooling or pressure release in some way or even for some form of maintenance or perhaps an urgent action in the knowledge that power ran out when the batteries ran out? Conjecture of course.

 

[AntonL]

4) The sidewise blast peeled back a part of the corner of Unit 4.

No, Unit 4 building was intact after the blast of Unit 3.
See https://www.physicsforums.com/showpost.php?p=3197547&postcount=539" after blast 3 and 4 posted in #539

I
I challenge everyone here, now knowing the additional information that has been added and the hypotheses being discussed of:
1) a blow out of the plug atop containment through the roof,
2) a blow out of the transfer gate aside the top of the containment through the SFP, or
3) some other explosion scenario

TCups from below schematic the plug is constructed of 4 layers criss-crossed semi circular sections.
If the plug is to blow then all 8 semicircular concrete section need to blow. Is there enough H2 and
O2 mix be in the volume immediately below plug and above containment dome to create this energy?

Fukushima may have a different plug configuration like a Hexaganal opening but the criss-cross arrangement
of 4 layers would remain, interlocking the plug sections.

http://img863.imageshack.us/img863/3206/reactor.jpg

 

[Astronuc]

Do new fuel rods go straight into the reactor after inspection.

No. They would go into storage after receipt inspection, because they are usually received while the current cycle is continuing, i.e., one receives the fuel before the outage. Some European utilities have a reloads-worth onsite, just in case. I'm not sure about Japanese practices.

The core maybe fully off-loaded, and the reinserts returned prior to the fresh fuel, since the reinserts provide activity to the detectors. Otherwise, the discharge full is removed, and an in-core shuffle is performed prior to loading new fuel.

In the case of Units 1-3, they were operating. Unit 4 was shutdown and the reinsert and discharge fuel were in the SFP. Not sure about fresh fuel - which would not be generating heat. The pool wouldn't be critical because of the accident, because it wasn't critical prior to the accident, and that would be less likely as a result of dryout.

 

[Astronuc]

Here is some preliminary evidence from the Test Ban Treaty Organisation that there has been no major destruction of the zirconium cladding:
| http://www.nature.com/news/2011/110317/full/news.2011.168.html
" ... the data show high amounts of volatile radioactive isotopes, such as iodine and caesium, as well the noble gas xenon. But so far, the data show no high levels of the less volatile elements such as zirconium and barium that would signal that a large meltdown had taken place ... "

Yes - as far as we know, only the fission gases (Xe, Kr) and some volatiles Cs, I, and maybe Rb, Br, and possibly Se and Te.

Absence of Np-239, Ce-144, Sr, Y, Ba, . . . . indicates that fuel particles have not escaped.

If only gases and volatiles are out - that would preclude an explosion (of or involving the fuel) or any process that would result in fuel particles becoming an aerosol form.

At the moment, it's not clear how a fire might occur if Zr-cladding is only on the order of 200C. We might see some ruptured endplugs with the tie rods being most vulnerable, or some localized accelerated corrosion associated with localized hydriding, perhaps in combination with some limited ballooning.

If the loss of coolant was due strictly to evaporation, then the breaches would more likely be at the top of the fuel rods, as opposed the case if there was a leak in the pool in which the fuel rods were exposed more rapidly, and the steam/air reaction occurred over a larger area.

Nevertheless, we're waiting for more evidence.

 

[AntonL]

No. They would go into storage after receipt inspection, because
they are usually received while the current cycle is continuing, i.e., one receives the fuel
before the outage. Some European utilities have a reloads-worth onsite, just in case. I'm not
sure about Japanese practices.

The core maybe fully off-loaded, and the reinserts returned prior to the fresh fuel, since the
reinserts provide activity to the detectors. Otherwise, the discharge full is removed, and an in-
core shuffle is performed prior to loading new fuel.

In the case of Units 1-3, they were operating. Unit 4 was shutdown and the reinsert and
discharge fuel were in the SFP. Not sure about fresh fuel - which would not be generating
heat. The pool wouldn't be critical because of the accident, because it wasn't critical prior
to the accident, and that would be less likely as a result of dryout.

IRSN state that 200 new fuel rod assemblies were delivered to Unit 4 thus increasing the quantity
from the reported 1331 to over 1500. Let's hope it is not MOX as the French are the main drivers
in marketing MOX

 

[Astronuc]

IRSN state that 200 new fuel rod assemblies were delivered to Unit 4 thus increasing the quantity from the reported 1331 to over 1500. Let's hope it is not MOX as the French are the main drivers in marketing MOX

It wouldn't be 200 MOX assemblies.

I don't know where UCS is getting there numbers, but it seems Unit 3 discharge 148 assemblies from the previous outage, or a little more than quarter core, but less than 1/3. Supposedly, there were 32 MOX assemblies in Unit 3.

The Japanese have been looking at MOX, for their own reasons, not because the French are pushing it.

 

[intric8]

Lay person here with a question for Astronuc

Simulations run out of a German weather site show huge plumes of Xenon 133. Was wondering if you could clarify the concentration and put it in meaningful terms? I don't know how to convert this to becquerel. I would be greatly obliged.

Link to the xenon simulation doesn't work, but here's a screenshot:

https://lh4.googleusercontent.com/-IYBgwGaz1Cs/TYgJi_qYQyI/AAAAAAAAABM/k6t8RR4LQG0/s1600/xenon.JPG

Here's the simulations for I131 and cs137 if you're interested in taking a look:

http://www.zamg.ac.at/aktuell/index.php?seite=1&artikel=ZAMG_2011-03-18GMT09:52

 

[Astronuc]

Lay person here with a question for Astronuc

Simulations run out of a German weather site show huge plumes of Xenon 133. Was wondering if you could clarify the concentration and put it in meaningful terms? I don't know how to convert this to becquerel. I would be greatly obliged.

Link to the xenon simulation doesn't work, but here's a screenshot:

I had problems with the xenon.jpg - I couldn't get an image. The site in Austria shows I-131 and Cs-137 plots. I'm not sure how the data are generated, i.e., source term and plume/atomspheric models, so I can't really give a reasonable statement.

There were similar dynamic gifs at the Der Spiegel site, but I don't know who did the plot and what assumptions are being made. I haven't seen any atmosphere measurements.

 

[intric8]

Thanks for the prompt reply sir. So we can assume that those simulations were modeled on unverifiable data, and therefore unreliable? I hope so... as they are quite unsettling.

 

[Astronuc]

Thanks for the prompt reply sir. So we can assume that those simulations were modeled on unverifiable data, and therefore unreliable? I hope so... as they are quite unsettling.

I certainly can verify any of the data, and I have no idea about the reliability, particularly the source term. I don't know of any atmospheric measurements which could be compared to those plume models.

 

[AntonL]

The site in Austria shows I-131 and Cs-137 plots. I'm not sure how the data are generated, i.e., source term and plume/atomspheric models, so I can't really give a reasonable statement.
.

http://www.zamg.ac.at/docs/aktuell/Japan2011-03-21_1500_E.pdf"
By what I can make of it, it is a theoretical simulation based on an assumed release and
nothing to do with actual release values.

I suppose you can email Dr G Wotawa directly and ask him.

 

[AntonL]

TEPCO underestimated tsunami, quake
Tokyo Electric Power Company says its nuclear power plants in Fukushima were hit by a
14-meter-high tsunami. That was more than double the maximum expectation.

The electric company on Monday checked the walls of the Fukushima Daiichi and Daini
nuclear power plants. It found that the water reached higher than 14 meters above sea
level.

The company had only expected a tsunami of 5.7 meters at the Daiichi plant and one of 5.2
meters at the Daini.

The Fukushima Daiichi plant lost sufficient cooling functions when the tsunami destroyed
facilities along the coast, such as seawater pumps and emergency diesel generators.

The buildings that house the reactors and turbines are built on grounds 10 to 13 meters
above sea level, but became partially inundated.

The power company said it had underestimated the biggest earthquake to be magnitude 8.
It said it admits that this month's magnitude 9 quake was beyond its calculation.

Tuesday, March 22, 2011 05:08 +0900 (JST)
.

However, villages are protected by a 10 metre Tsunami wall, needless to say they were
breached and http://en.wikipedia.org/wiki/Historic_tsunamis" list numerous Tsunamis 20 metres plus. We are witnessing a designed "accident-in-waiting";
same can happen at San Onofre southern California and many more others .

 

[|Fred]

The origin of this line of reasoning was the the possibility that the lava-like discharge from the hole in the north side of reactor 4 is corium. Corium would emit gamma rays. I have no way of ruling out lofted radio-nucleotides as the source of the radiation.

the presence of Corium outside the reactor is inconstant with the isotopes founded so far

 

[AtomicWombat]

Astronuc,

Are you aware of failure mechanisms involving an explosion in the wet well?

It has occurred to me that the reactor (85 atm design) is exceptionally robust compared to the primary containment (5 atm design). An explosion in the wet well could simply blast past the reactor without penetrating it, but blowing the concrete plug high into the sky.

 

[PietKuip]

UCS details on SFPs:

http://allthingsnuclear.org/post/4008511524/more-on-spent-fuel-pools-at-fukushima"

I now read their http://allthingsnuclear.org/post/3964225685/possible-source-of-leaks-at-spent-fuel-pools-at" . And I am flabbergasted by how these things are designed: the gates are sealed with an inflatable thing that needs to be kept pressurized by electrical power. Without electricity, water will be running out. And this had happened in the US at the Hatch nuclear plant in Georgia in 1986. There someone had closed a valve. They cought it in time, but if water levels had fallen further, radiation levels would have made it difficult to fix the problem.

So maybe there is no structural damage or cracks in the concrete caused by the quake or the tsunami. The leaks in all these pools are a consequence of design, almost guaranteed to happen when electrical power is lost. That is very worrisome.

 

[TCups]

REACTOR UNIT 3 BUILDING ORIENTATION?

Starting with the diagram found here:
http://modernsurvivalblog.com/wp-co...ral-electric-boiling-water-reactor-mark-I.jpg

1) If this general schematic is correct (and I realize it may not be), then the north-south axis of the core's center is located west of the central north-nouth axis of the building, but the east-west axis of the core is centered.

2) It appears that a tunnel structure at ground level is located where the well shaft for the fuel assembly lift with the crane takes place. A very similar tunnel exits the southwest corner of Bldg 3 and, this appears to coincide with where, on the west side of Bldg 3 the refueling trucks were parked.

3) It appears that the upper portion of the shaft (intact, or largely intact) and a portion of a pool, severely damaged, can be seen on the helicopter fly-over photos. The helicopter spends a long time looking at the southeast corner of the building.

4) The location of the overhead crane is not a constant reference as it can be moved north-south

5) From this information, I have concluded that the SFP in Unit three is nearest the southeast corner of Bldg 3, and that appears to me to be the epicenter of the blast, directed upward and to the south, toward Bldg 4.

(see attached annotated diagram, NorhtSouthOrientation.jpg)

Any errors in this logic?
OOPS! the original NorthSouth diagram was incorrectly annotated. I have corrected it. Sorry!

After the explosion, from the helicopter fly over, this is the view from the southeast corner. One can see part of a tunnel structure exiting the back (west side, southwest corner) of the building, a part of the well shaft, what appears to be a blown out SFP in the southeast corner and steam venting from where the head of the primary (dry) containment of the reactor core might be.

(see picture38)

Part of Building 4 is included. In closer detail, it is apparent that the top of the north face of Bldg 4 has been blasted inward (not melted as earlier posted). If you look closely at several of the views of the northeast corner of Bldg 4, you can even see that the concrete pillar at the northeast corner of Bldg 4 buckles inward, presumably also from the blast. Although it has been posted that the north side of Bldg 4 was intact after the blast (at least it lacked the large, square hole we later concentrated on), it appears to me that blast damage occurred to Bldg 4. In fact, shrapnel from Bldg 3 may have penetrated the exterior of Bldg 4, not been visible by satellite, and may have been responsible for the later fire and additional damage at Bldg 4. Note also that a portion of the roof of Bldg 4 is peeled back.

(see pictre 37)

Does anyone find any error with these observations?

More later as I have time today.

 

[jensjakob]

Place of SFP is confirmed by Japanese authorities and mentioned in CNN and BBC

 

[artax]

how do you screen grab from you tube?

i'll try this
http://www.youtube.com/watch?v=z9fKtXDaQVc&feature=player_detailpage#t=54s

no just starts playing the vid there I'll photo my screen!

BUMP!

Not a very good image I know, but the vid has been pulled from you tube japan, and these fuel rods are s'posed to be a few cm thick and four metres long, and I assume very stiff as they're ceramic (?) or is that just the pills inside?
Anyway, would anyone else like to suggest what these are falling out the back (seaward or eastern side of unit 3

 

[AntonL]

REACTOR UNIT 3 BUILDING ORIENTATION?

Starting with the diagram found here:
http://modernsurvivalblog.com/wp-co...ral-electric-boiling-water-reactor-mark-I.jpg

1) If this general schematic is correct (and I realize it may not be), then the north-south axis of the core's center is located west of the central north-nouth axis of the building, but the east-west axis of the core is centered.

2) It appears that a tunnel structure at ground level is located where the well shaft for the fuel assembly lift with the crane takes place. A very similar tunnel exits the southwest corner of Bldg 3 and, this appears to coincide with where, on the west side of Bldg 3 the refueling trucks were parked.

3) It appears that the upper portion of the shaft (intact, or largely intact) and a portion of a pool, severely damaged, can be seen on the helicopter fly-over photos. The helicopter spends a long time looking at the southeast corner of the building.

4) The location of the overhead crane is not a constant reference as it can be moved north-south

5) From this information, I have concluded that the SFP in Unit three is nearest the southeast corner of Bldg 3, and that appears to me to be the epicenter of the blast, directed upward and to the south, toward Bldg 4.

(see attached annotated diagram, NorhtSouthOrientation.jpg)

Any errors in this logic?

TCups, SFP has been stated to be in SE corner of building, At fukushima reactor 1 is north of reactor 4, you have North South interchanged

(By the way you can image link and attachment) as I have done here by clicking on the thumb twice)
https://www.physicsforums.com/attachment.php?attachmentid=33373&d=1300788049

https://www.physicsforums.com/attachment.php?attachmentid=33373&d=1300788049