Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[jensjakob]

Fukushima Daiichi nuclear power plant near the sea damaged by the earthquake east, found that the concentration of radioactive material falls up to 126 times the safety standards, announced at a press conference early Tuesday TEPCO 22.

According to TEPCO, near the outlet 21 at 2:30 pm were examined with 0.5 liters of water collected, the criteria established by the Nuclear Reactor Regulation Law is 126.7 times the iodine 131 was detected. This water year, and continue to take every day, the annual limit public exposure to radiation falls on 126.7-fold (nuked) will be. Cesium 134 is a standard 24.8-fold addition, the cesium-137 detected 16.5-fold

http://translate.google.com/translate?sl=ja&tl=en&js=n&prev=_t&hl=da&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.asahi.com%2Fnational%2Fupdate%2F0322%2FTKY201103210384.html

 

[PietKuip]

One note: 5.9 milliBq/cm3 is not over any limit. Even if it was 5.9KBq/cm3 it would be be the Occupational DAC (10 CFR 20, Appendix B) limit of 7.4E3 Bq/cm3. Hope my conversions are correct!

No, those would be horrible levels. http://www.nrc.gov/reading-rm/doc-collections/cfr/part020/appb/Iodine-131.html" says that the inhalation DAC for I-131 is 2E-8 microcurie per ml, which is 0.74 milliBq/cm3.

 

[HansHooligan]

Hi. In this video at about 4:19 in my opinion has fuel rods
Look at the shape of those, looks just like these

What you think?

edit: It seems this video was here already. Just missed it because screen caps are not visible anymore due to exceeded bandwith.. :|

 

[Maxion]

Hi. In this video at about 4:19 in my opinion has fuel rods
Look at the shape of those, looks just like these

What you think?

edit: It seems this video was here already. Just missed it because screen caps are not visible anymore due to exceeded bandwith.. :|

When looking at the video you can quite clearly see the so called fuel rods extending out from concrete slabs at steady intervals. That is rebar, not fuel rods.

Also if you look at the IR shots from today you see no heat signature from where these so called fuel rods are. If these were real fuel rods they would be warmer than ambient.

 

[HansHooligan]

I missed that "at steady intervals", seems more like "just a bunch of sticks".
I don't think that those thermal images are accurate enough to show 10mm thick fuel rods unless those are at really high temperature.

Just my 2 cents.

 

[Maxion]

I missed that "at steady intervals", seems more like "just a bunch of sticks".
I don't think that those thermal images are accurate enough to show 10mm thick fuel rods unless those are at really high temperature.

Just my 2 cents.

With THAT many fuel rods close together they would show. The only "proof" there is of those being fuel rods is a layman's opinion after looking at some shaky, low resolution and blurry footage. Also real fuel rods are bunched together in bundles. If they were fuel rods, how could all of the fuel rods be completely detached from their bundles and still staying that intact as in the video? And have no of the bundle parts attached to them?

And on top of that we also have the IR images showing NO heat from that area. Keep in mind thermal imaging resolution does not work the same way as resolution in a regular camera. Heat coming from a 1cm thick rod will not require a 1cm/pixel resolution of the camera since heat radiates and heats up stuff around the object producing heat.

IF they are fuel rods I will eat my hat.

 

[TCups]

When looking at the video you can quite clearly see the so called fuel rods extending out from concrete slabs at steady intervals. That is rebar, not fuel rods.

Also if you look at the IR shots from today you see no heat signature from where these so called fuel rods are. If these were real fuel rods they would be warmer than ambient.

I don't know if these are fuel rods or some other rod. I don't know the exact relationship of the location of the "rods" to the heat signatures seen on the IR photos posted today. I do know that after the explosion, in this pile of rubble, in this field of view, it would be somewhat reassuring to see even one bent piece of a rod. Absent that, one possible conclusion is that these rods seem to be much more rigid than the bent rebar seen in other areas. If any of these were once embedded in concrete, I can see no conclusive evidence of it on this shot.

I also believe that the green structure in the lower right may be part of the fuel rod handling equipment. If so, then it might support the notion that these are at least somewhere near the location of the SFP.

I also believe the reports that some high level radioactive debris are on the ground and that they have sufficient activity, if not obvious heat, to warrant the workers using dozer blades attached to military tanks to clear the high-level radioactive debris to permit safer access to work on units 3 & 4. There aren't that many different possibilities of sources for high-level radioactive debris on the ground that I can think of.

I suspect I can no more convince anyone these are fuel rods than anyone can convince me that after the explosion, all the fuel rods are still in the SFP and that they survived the blast, unscathed.

 

[aamrwc]

The JPG picture T-cup shows doesn't look like re bar to me. RE bar would bend. There are other pictures of bend re bar in other clips. These sure look like a pile of fuel rods like in #757. None of it is bent and I don't see any attached concrete

 

[AtomicWombat]

@Wombat
Well if I'm not mistaken in your calculation you assume that the radiation level measure taken at x meters are "induce" from the radiation source hence your reverse invert square law calculation.

In my opinion you are likely making a false assumption / interpretation : The radiation source are more likely the volatile isotope in the air , at least for the most part.


ps: to make my self more understandable your calculation would be right if let say you had a pile of radioactive isotope outside your windows, you were in your house and wanted to know how radioactive this pile was taking a measurement from a distance. But what we have here is a window leaking and wind blowing some of the stuff to the inside..

Thanks for your comment 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.

See:
https://www.physicsforums.com/showpost.php?p=3193343&postcount=331
https://www.physicsforums.com/showpost.php?p=3194084&postcount=381
https://www.physicsforums.com/showpost.php?p=3195114&postcount=416

I have no way of ruling out lofted radio-nucleotides as the source of the radiation.

 

[TCups]

Here are a few questions for those more sure than me to ponder:

What is a reasonable estimate of the mean age of spent fuel rods stored in a SFP after removal from the reactor? Is it possible that after many months or years in the SFP the rods might have exhausted the residual heat to level that they would not glow and might be lost in the background heat signature coming from the ruins of Unit 3?

What might become of the contents of one of those casks coming off or going back on one of the two refueling flatbed trucks seen out back of unit 3 in the satellite photos?

Are shiney, "new" low level enriched uranium (oxide?) fuel rods that have not been in a reactor extremely hot before the fission reaction has occurred in the core of a reactor?

If a fuel rod cask were being downloaded or uploaded, what would the actual process be? Might there be some point in the re-fueling or de-fueling process where the rods would be out of the racks and perhaps in a state or location more vulnerable to a disastrous accident like the current chain of events?

How robust are the racks and individual rod bundles that hold together a fuel rod assembly.

How robust are the casks in which fuel rod assemblies are transported?

If the fuel rods are spent (with respect to the level of fissionable materials present necessary to sustain an efficient chain reaction in the core), then would it be reasonable to suspect loosely scattered rods such as these pictured, if they were spent, would necessarily heat up more in their haphazard arrangement?

I don't know the answer to any of these questions.

 

[rhody]

Here are a few questions for those more sure than me to ponder:

What is a reasonable estimate of the mean age of spent fuel rods stored in a SFP after removal from the reactor? Is it possible that after many months or years in the SFP the rods might have exhausted the residual heat to level that they would not glow and might be lost in the background heat signature coming from the ruins of Unit 3?

What might become of the contents of one of those casks coming off or going back on one of the two refueling flatbed trucks seen out back of unit 3 in the satellite photos?

Are shiney, "new" low level enriched uranium (oxide?) fuel rods that have not been in a reactor extremely hot before the fission reaction has occurred in the core of a reactor?

If a fuel rod cask were being downloaded or uploaded, what would the actual process be? Might there be some point in the re-fueling or de-fueling process where the rods would be out of the racks and perhaps in a state or location more vulnerable to a disastrous accident like the current chain of events?

How robust are the racks and individual rod bundles that hold together a fuel rod assembly.

How robust are the casks in which fuel rod assemblies are transported?

If the fuel rods are spent (with respect to the level of fissionable materials present necessary to sustain an efficient chain reaction in the core), then would it be reasonable to suspect loosely scattered rods such as these pictured, if they were spent, would necessarily heat up more in their haphazard arrangement?

I don't know the answer to any of these questions.

TCups,

All very good, well organized, clearly stated questions... simple answer... where is Astronuc !

Rhody...

 

[TCups]

TCups,

All very good, well organized, clearly stated questions... simple answer... where is Astronuc !

Rhody...

On his way to Japan? He said that was his immediate goal if he could get there.

 

[dallasbrew]

cask integrity:

I don't know about modern ones, but back when I was going to nuke school, it was noted that they were designed to drop, burning from a truck on an overpass into the path of a train and not be compromised.

They are supposed to be pretty tough things.

 

[rhody]

On his way to Japan? He said that was his immediate goal if he could get there.

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...

 

[gmax137]

Here are a few questions for those more sure than me to ponder:

What is a reasonable estimate of the mean age of spent fuel rods stored in a SFP after removal from the reactor? Is it possible that after many months or years in the SFP the rods might have exhausted the residual heat to level that they would not glow and might be lost in the background heat signature coming from the ruins of Unit 3?

Mean age? probably 10 to 20 years. They would certainly not be 'glowing' hot.

What might become of the contents of one of those casks coming off or going back on one of the two refueling flatbed trucks seen out back of unit 3 in the satellite photos?

I expect they’re putting fuel into dry storage casks, though I really don’t know.

Are shiney, "new" low level enriched uranium (oxide?) fuel rods that have not been in a reactor extremely hot before the fission reaction has occurred in the core of a reactor?

The new fuel isn’t even warm to the touch. You could safely keep it in your kitchen.

If a fuel rod cask were being downloaded or uploaded, what would the actual process be? Might there be some point in the re-fueling or de-fueling process where the rods would be out of the racks and perhaps in a state or location more vulnerable to a disastrous accident like the current chain of events?

Not sure what you mean here. I don’t think the rods are pulled from the assemblies at any time.

How robust are the racks and individual rod bundles that hold together a fuel rod assembly.

They are very robust. If you dropped an assembly from the crane you might bend the first row.

How robust are the casks in which fuel rod assemblies are transported?

Here in the US they are extremely robust. Google for videos of the casks being hit by locomotive at high speed, etc.

If the fuel rods are spent (with respect to the level of fissionable materials present necessary to sustain an efficient chain reaction in the core), then would it be reasonable to suspect loosely scattered rods such as these pictured, if they were spent, would necessarily heat up more in their haphazard arrangement?

No, the arrangement doesn’t alter the heat generated in any given rod; the heat is just the fission products decaying away at their given rate.

I'm not a BWR guy so these are just my best guess answers. Hope that helps.

 

[TCups]

Aside:
OK, I bit the bullet and spent $2.99 (not auto renewing) and paid by PayPal so I have unlimited bandwidth for the next 30 days. The links in the previous posts should be working once more. Now I am even more "invested" I suppose.

 

[TCups]

Mean age? probably 10 to 20 years. They would certainly not be 'glowing' hot.I expect they’re putting fuel into dry storage casks, though I really don’t know.The new fuel isn’t even warm to the touch. You could safely keep it in your kitchen.Not sure what you mean here. I don’t think the rods are pulled from the assemblies at any time.They are very robust. If you dropped an assembly from the crane you might bend the first row.Here in the US they are extremely robust. Google for videos of the casks being hit by locomotive at high speed, etc.No, the arrangement doesn’t alter the heat generated in any given rod; the heat is just the fission products decaying away at their given rate.

I'm not a BWR guy so these are just my best guess answers. Hope that helps.

OK, so it would not be reasonable to expect a sideways blast into the SFP could "disassemble" a fuel rod assembly, I suppose. Probably not even with a shock wave traveling through water rather than air. But it seems possible, in the unlikely event that these are fuel rods, that they might not have a high heat signature in the IR range. Now we need some x-ray imagery of the site, I suppose.

The question of the origin of the unbent rods remains unanswered.

 

[AtomicWombat]

First IR image released in news broadcast

Hot spot over spent fuel pools indicated as 128 deg C and multiple hot spots at other places
(at the moment I cannot listen to the broadcast - only watch so no idea what they saying

Well 128 C means the SFP (assuming that is what it is) is definitely not covered with water (at atmospheric pressure) at the time of the IR photo. Steam at atmospheric pressure will usually only be at 100 C. So whatever is being viewed is solid or the solid crust of a molten mass.

Can anyone direct me to the original source of these IR images?

 

[AtomicWombat]

I tried last evening, for a good hour, to confirm from any independent source, the exact layout of the floor plans of any of the units at Fukushima.

Does anyone have a better source for the actual "anatomy" of what the Fukishima facility is supposed to be, rather than a stylized schematic? A blueprint or floor plan would certainly help to be able to draw more informed conclusions about what is seen.
Thanks.

TCups,
I think you can safely assume that the SFP and equipment pool straddle either side of the reactor on the long orientation of the reactor building (i.e the 45 m length). The large crane spans the 35 metre dimension of the building. So the SFP and equipment pool will be approximately centred on the north and south walls of each reactor building, or perhaps slightly offset from the centre line.

I think you are basically correct. The hole just above the steam is the SFP. The steam in the image comes from roughly from the "cattle run" between the reactor and the SFP. The hole to the right, with the "cut-out" of the steel frame above it, is the reactor plug hole.

 

[Reno Deano]

Here are a few questions for those more sure than me to ponder:

What is a reasonable estimate of the mean age of spent fuel rods stored in a SFP after removal from the reactor? Is it possible that after many months or years in the SFP the rods might have exhausted the residual heat to level that they would not glow and might be lost in the background heat signature coming from the ruins of Unit 3?

At one time before moving "old" spent fuel from the SFP to Dry Casks, the age could have been 10 years or more. Due to the 2/3 burn-up the long lived fission products (Cs-137, PU, etc, would give then a good heat signature.

What might become of the contents of one of those casks coming off or going back on one of the two refueling flatbed trucks seen out back of unit 3 in the satellite photos?

Coming off the truck they would be empty. Going on they would be full and destined for fuel reprocessing in France

Are shiney, "new" low level enriched uranium (oxide?) fuel rods that have not been in a reactor extremely hot before the fission reaction has occurred in the core of a reactor?

HE fuel bundles (navy type is room temperature.) LE Fuel bundles is less than room temperature, and individual rods are ambient temperature.

If a fuel rod cask were being downloaded or uploaded, what would the actual process be? Might there be some point in the re-fueling or de-fueling process where the rods would be out of the racks and perhaps in a state or location more vulnerable to a disastrous accident like the current chain of events?

Spent fuel bundles/modules are either loaded into casks under water or by a shielded transfer container. Pieces of rods are keep out of the casks.

How robust are the racks and individual rod bundles that hold together a fuel rod assembly.

Robust enough to withstand high pressure oscillations with within the core and incidents normal to transportation. The SFP racks are designed with seismic considerations.

How robust are the casks in which fuel rod assemblies are transported?

Almost indestructible. Goggle: DOE Spent Fuel Shipping Cask Testing

If the fuel rods are spent (with respect to the level of fissionable materials present necessary to sustain an efficient chain reaction in the core), then would it be reasonable to suspect loosely scattered rods such as these pictured, if they were spent, would necessarily heat up more in their haphazard arrangement?

The picture is from a fuel manufacturing facility, prior to them being placed into the fuel bundle matrix/array. Spent fuel rods from power reactors would be oxidized and not sparkling.
I don't know the answer to any of these questions.

See italicised answers below your questions.

 

[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.