Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[james14]

International nuclear experts believe that melted fuel in reactor No. 1 has caused a "localized criticality," which is a small, uncontrolled chain reaction that occasionally emits a burst of heat, radiation and a blue flash of light.http://abcnews.go.com/International...er-speaks-radiation-dangers/story?id=13271759

I do wonder if this is actually true, of it's more a case of one news provider copying another

 

[rhody]

http://www-pub.iaea.org/mtcd/publications/pdf/pub1106_scr.pdf"

55 Pages... a fascinating and terrifying read.

On 17 June 1997 a criticality accident occurred at the Russian Federal Nuclear Centre (formerly known as Arzamas 16) in the town of Sarov, near Nizhnij Novgorod, about 400 km east of Moscow. The accident happened in a routine manipulation of the components of a critical assembly. The overexposed man, a skilled technician, died 66 h later from the effects of his exposure, despite prompt and intensive medical management. This was thus a very rare type of fatality.
with an experienced technician.

Rhody...

 

[shogun338]

I'm skeptical of such reports. I believe part of the problem is translation.

One so-called beam was reported at 1.5 km from the plant. I can't see a colimated beam at the that distance. The source would have to be pretty intense, and I'd imagine that folks at the plant would receive a fatal dose.

I would like folks to use reliable sources, and treat media reports with a healthy amount of skepticism. I have read a lot of nonsense claims, some published by self-proclaimed or purported experts.

Here is a link about the Tokaimura Accident that happened in Japan. It was neutrons that killed the workers I believe . http://www.mun.ca/biology/scarr/4241_Tokaimura_Accident.html

 

[geb.es]

I can suggest one: superheated steam & gas blow out the fuel transfer chute into the upper SFP (water already hot, or boiling, rapidly vaporizing the water, and resulting in an upward focused blast out of the SFP, launching the FHM skyward, yanking a fuel rod assembly out of the pool as it shoots upward, then crashing on the north end of bldg 3.

I had thought that the original blast at Bldg 3 is on the SOUTH end of the building. The damage on the north end sends stuff crashing downward. If the blast photo is taken from inland, looking eastward, then the blast is to the right, southward. Two towers bracket Bldg 4, on the blast (south) side of Bldg 3. A large hunk of debris comes down on the north side of Bldg 3. But the more I look, I can't make that orientation fit with the towers. Someone help me here.

http://i306.photobucket.com/albums/nn270/tcups/Picture28.png

http://i306.photobucket.com/albums/nn270/tcups/Top.png

Doesn't this view have to be from the west?
http://i306.photobucket.com/albums/nn270/tcups/Picture28.png

@TCups: look at 1:51 in this video. Something heavy is falling down and is deviated, or turned around, by the big antenna, so we can presume it landed very close to the antenna:

https://www.youtube.com/watch?v=YN8tzmtQv8g

Might that be part of the FHM?

EDIT: I corrected the youtube tags. Also, I am not completely sure whether the object I mentioned is turned around or it simply partly disappears behind the antenna. What seems clear is that at least three objects fall. Two simultaneously (or they might be parts of the same, big, object) one to the right and one slightly to the left of the antenna. Then a third one, about a second later, and to the right of the antenna...

 

[Astronuc]

Here is a link about the Tokaimura Accident that happened in Japan. It was neutrons that killed the workers I believe . http://www.mun.ca/biology/scarr/4241_Tokaimura_Accident.html

They were mixing an aqueous solution of highly enriched (~18.8% U-235). The BWR fuel at Fukushima is ~4%.

In the case of Tokaimura, it would be a combination of neutrons and gamma radiation, and those exposed were inches from the vessel. One guy apparently collapsed onto the vessel.
http://en.wikipedia.org/wiki/Tokaimura_nuclear_accident

 

[Bob S]

Reports of a "blue flashing light." Not sure where they got this news or if there's any proof.

Here is an article about Ed McMillan (Nobel Laureate) putting his head in a charged particle beam and seeing blue flashes in his eye. "Hey, there's one!" he shouted.

http://www.time.com/time/magazine/article/0,9171,903128,00.html

Bob S

 

[razzz]

Even though I know nothing about nuke plants, I know you have the chance to see every combination of every possible scenario here. Doubt operators readings are wrong, probably under-reported as time will tell. The world doesn't get polluted because of a lack of real time reliable readings. And what is the time frame of events being without some type of coolant to the reactors and pools? If when venting pressure, was anything going into replace the pressure or was it just automated by relief valves trying to save the core? Pool(s) status just a bit easier to monitor but without re-watering...

Unit 3 explosion needs input from someone that can calculate the amount of force it takes to create such a blast. The sound track is just as scary as the visual. Doesn't unit 3 report containment shell pressure as matching ambient? Probably because it doesn't exist any longer as resembling a shell. The reactor vessel shell might still exist but has a hole the bottom of it. You have a couple (or more) of ground zero(s) in progress.

Workers refusing to enter the field even before any re-water operations were contemplated speaks volumes.

Basically a nuke complex ran out of water, what did you expect would happen? I didn't know there was a dam in the area, they could have gravity fed the whole place.

Pollute the Pacific to keep the hot spots cool, that is all you can do in this instance. Background noise of moving concrete boom trucks into position is a telltale sign.

Chernobyl is still trying to locate the remaining core parts, hoping to find them before groundwater does as they only capped ground zero as a stopgap measure. BTW, their first capping didn't go well. Further plans for a more permanent cap planned as the nightmare never ends there.

How would you like to place a mass of concrete then have Earth tremors fracture it like a windshield? It won't be easy to cap here. Better to find the pieces and put them somewhere so you know where everything is before throwing a blanket over it.

 

[Bez999]

@Tcups: Regarding your latest scenario (the flying fuelmachine). I can't find fault with it thus far, particularly because it ties together bits of information that didn't make sense before, especially how these rods could have ended up on that side of the building. While it seems a wild theory to have them attached to the entire FHM, which does a backflip through the air, it all fits with what we can see. Note that most damage to the buildings where the FHM now sits was caused by the explosion and debris of the wall BEFORE the machine landed on top of the rubble. Also for the FHM to be able to drag a fuel bundle along without it shearing off, it must have been propelled upward almost vertically, which corresponds with it landing close to its departure point.

 

[TCups]

FLOOR PLAN LAYOUT OF REACTOR BUILDINGS 3 AND 4, TO SCALE, HIGH RESOLUTION

As for atomicinsights, I wouldn't put a lot of stock in the article.

The Fukushima units are not the same as Oyster Creek, even though they may have Mk I in common. I'm not aware of upper and lower SFP pools.

Astronuc:
'tis true Oyster Creek is probably a bit different layout. My Illustrator skills are not as good as Photoshop, but I took this diagram

http://www.flickr.com/photos/60551543@N04/5531996321/sizes/z/in/photostream/

Did a scaled overlay sketch of the floor plan layout of the reactor access floor . . .

http://i306.photobucket.com/albums/nn270/tcups/Picture63.png

Copied it to Photoshop and touched it up . . .

http://i306.photobucket.com/albums/nn270/tcups/TopFloor-Floorplan.jpg

Scaled the measurements and structures relative to the high resolution top down views from the fly-over provided by Fred's post (there is some distortion due to differences in perspective between the two buildings), and come up with something like this.

http://i306.photobucket.com/albums/nn270/tcups/aerial-floorplan.gif

It may not be exact, but I expect it's pretty darned close -- as close as I can come without the actual floor plans.

I believe there are upper and lower pools on the south side, but one of the pools, at least on the only diagram I seem to have that shows this region of a Mark I, is narrow and deep. It seems to have a transfer gate. Is it for temporary cask storage? One important feature, if the layout is correct -- the fuel handling machine would not straddle the additional small pool on the south side. It can be accessed with the large overhead crane. I the diagram, it would seem to be a place where the yellow cask being lifted up the chute would be placed, and in that location, the spent fuel rod assemblies could be placed "wet" in the fuel cask.

 

[TCups]

REGARDING A BALLISTIC FUEL HANDLING MACHINE

@Tcups: Regarding your latest scenario (the flying fuelmachine). I can't find fault with it thus far, particularly because it ties together bits of information that didn't make sense before, especially how these rods could have ended up on that side of the building. While it seems a wild theory to have them attached to the entire FHM, which does a backflip through the air, it all fits with what we can see. Note that most damage to the buildings where the FHM now sits was caused by the explosion and debris of the wall BEFORE the machine landed on top of the rubble. Also for the FHM to be able to drag a fuel bundle along without it shearing off, it must have been propelled upward almost vertically, which corresponds with it landing close to its departure point.

If there were fuel handling operations in progress and the quake hit, then power failed and the reactor scrammed. It seems plausible that the operators would put the fuel assembly they were handling back in a safe position (if the fuel handling machine could draw power from the backup diesel generators, otherwise not), then get the heck out of there to see what was going on. Think about it -- working up there above the SPF and a big quake hits.

Also, I have absolutely no first hand experience, but from the pictures, the part of the fuel handling machine that handles the fuel assemblies is not a cable or anything like it. It looks like a rigid vertical arm, probably hydraulic, and I would be willing to bet it was built to be very precise, hold the fuel rod assemblies very securely, and put them in exactly the right spot.

If the blast resulted in the same initial trajectory and velocity of the FHM and attached fuel rod assembly, then, the point of impact would be about the same, I should think.

How about it Astronuc? What are the actual mechanics of a FHM and how does it attach to and secure a fuel rod assembly for movement?

 

[Astronuc]

Also, I have absolutely no first hand experience, but from the pictures, the part of the fuel handling machine that handles the fuel assemblies is not a cable or anything like it. It looks like a rigid vertical arm, probably hydraulic, and I would be willing to bet it was built to be very precise, hold the fuel rod assemblies very securely, and put them in exactly the right spot.

If the blast resulted in the same initial trajectory and velocity of the FHM and attached fuel rod assembly, then, the point of impact would be about the same, I should think.

How about it Astronuc? What are the actual mechanics of a FHM and how does it attach to and secure a fuel rod assembly for movement?

The fuel handling machine has a telescoping fuel mast. On the lower end is a grapple with interlocking fingers. The fingers close on the handle, or bail, which is an integral part of the upper tieplate of a BWR fuel assembly.

For fuel handling equipment, see - http://www.parnuclear.com/ParNuclear/docs/PaRNuclearBrochure.pdf

See the diagram for a BWR fuel assembly. Notice the handles on top of the fuel assemblies and control blades.

 

[TCups]

The fuel handling machine has a telescoping fuel mast. On the lower end is a grapple with interlocking fingers. The fingers close on the handle, or bail, which is an integral part of the upper tieplate of a BWR fuel assembly.

For fuel handling equipment, see - http://www.parnuclear.com/ParNuclear/docs/PaRNuclearBrochure.pdf

See the diagram for a BWR fuel assembly. Notice the handles on top of the fuel assemblies and control blades.

So, in the last diagram, 4 fuel assemblies surround a cruciform control blade. The fuel handling machine's "mast" handles each of the 4 assemblies, individually, correct? How many individual rods are in each of the 4 assemblies?

Would the emergency diesel back up generators power the fuel handling machinery if the plant lost power?

 

[Astronuc]

So, in the last diagram, 4 fuel assemblies surround a cruciform control blade. The fuel handling machine's "mast" handles each of the 4 assemblies, individually, correct? How many individual rods are in each of the 4 assemblies?

Would the emergency diesel back up generators power the fuel handling machinery if the plant lost power?

Each fuel assembly is grappled individually.

In the fuel used at Fukushima, the fuel array is an 8x8 lattice. A large central water rod occupies the area that would otherwise be occupied by 4 fuel rods. So there are 60 fuel rods in the FK fuel. Four assemblies have represent 240 fuel rods.

It's possible the EDGs would power the refueling machine. However, if the EDGs are running in an emergency, I seriously doubt that anyone would be moving fuel!

At the moment, we don't know the condition of the SFPs in Units 1-4. I doubt that anyone will be able to get near them, given the level of contamination.

TEPCO personnel will have to remove the debris from the upper containment areas before the SFPs can be addressed. Unit 2 may be the least problematic, whereas the upper structures of Units 1, 3, and 4 are obviously destroyed.

More importantly, the overhead crane is necessary to move heavy equipment, including the containment plug, cover, RPV head, steam dryers, . . . , as well as the spent fuel casks and spent fuel racks. SFP racks can be moved, but they must be empty.

Any equipment from the core must be clean. Any equipment must be stored and handled under water. If equipment is contaminated with radioactive deposits, the deposits must be removed (the equipment must be decontaminated).

 

[Bez999]

@Tcups: It looks like the telescopic arm has an attachment that grasps one fuel assembly at a time. There is an attached camera to assist in locating the thing precisely, i.e. making sure the machine is placed exactly plumb with the assemblies in the storage rack or rector, so when it extracts vertically (because it is a boom, not a cable, there is little leeway), everything lines up.

 

[TCups]

@TCups: It looks like the telescopic arm has an attachment that grasps one fuel assembly at a time. There is an attached camera to assist in locating the thing precisely, i.e. making sure the machine is placed exactly plumb with the assemblies in the storage rack or rector, so when it extracts vertically (because it is a boom, not a cable, there is little leeway), everything lines up.

Pure speculation, perhaps, but I think reasoned speculation on my part is that 60 is a number that might make sense for the number of individual alleged "fuel rods" seen at the alleged "crash site"

http://i306.photobucket.com/albums/nn270/tcups/903a9527.jpg

http://i306.photobucket.com/albums/nn270/tcups/FHMCrater.png

 

[shogun338]

They were mixing an aqueous solution of highly enriched (~18.8% U-235). The BWR fuel at Fukushima is ~4%.

In the case of Tokaimura, it would be a combination of neutrons and gamma radiation, and those exposed were inches from the vessel. One guy apparently collapsed onto the vessel.
http://en.wikipedia.org/wiki/Tokaimura_nuclear_accident

In the Tokaimura accident neutron beams traveled a distance of 500 meters and exposed civilians to 1mSv per hour during the 20 hours of the criticality .They also saw a blue flash in the room when they mixed in the last bucket . This seems like a lot from such a small accident . In the case of Fukushima there's way more fuel laying around . Does the fuel being 4% make that big of a difference ? What about the MOX fuel ?

 

[Astronuc]

In the Tokaimura accident neutron beams traveled a distance of 500 meters and exposed civilians to 1mSv per hour during the 20 hours of the criticality .They also saw a blue flash in the room when they mixed in the last bucket . This seems like a lot from such a small accident . In the case of Fukushima there's way more fuel laying around . Does the fuel being 4% make that big of a difference ? What about the MOX fuel ?

The enrichment is very significant with respect to criticality, and the fact that fuel is normally heterogenous, i.e., separate from the coolant. However, if a large amount of fuel is exposed to coolant, and becomes soluble, that's an entirely different matter. However, the enrichment is still critical.

What about the MOX fuel? It's in the core. Even if the core achieved criticality, from essentially a zero power configuration, it's in the core. The neutron flux is not going to be as intense as it was under full power operation, so there is no way that it would create a 'neutron beam'.

If the fuel were dispersed outside of the core, e.g., in the torus, then it is much less likely to achieve a critical configuration becuase of the less favorable geometry.

 

[NUCENG]

OK, that analysis fits pretty darned well compared to my earlier guesstimate:

https://www.physicsforums.com/attachment.php?attachmentid=33874&d=1301669768

https://www.physicsforums.com/attachment.php?attachmentid=33875&d=1301672183

Even the shadow on the south side of Bldg 4 lines up.


Here are a couple of additional questions for critical analysis by someone who knows and can critically analyze photos for that sort of thing, Anton:

Do the size, number and distribution of the rod like objects in this photo fit the description of the number of 4 meter x 3 cm (roughly?) individual fuel rods that might be in a single fuel rod assembly?

http://i306.photobucket.com/albums/nn270/tcups/64f1c409.jpg

Does it make sense that a flying fuel handling machine would drag an attached single fuel rod assembly behind like the tail of a kite and that the fuel rod assembly would smash open on top of the bulk of the FHM as the FHM impacts the building?

Do the girders about the proposed NE corner impact site look to be bent downwards vs the upward and outward bending at the blast site on the SE corner?

A 10x10 fuel assembly has individual fuel rods with a top plate and handle assembly, a bottom plate and nozzle, and three spacer plates. All rods are inserted through the spacer plates.

Fuel assemblies are not robust structrures. I have seen results of dropping new fuel assemblies prior to channeling which resulted in significant tamage to rods. They do not tolerate even small twisting or side loads. That is part of the reason each fuel assembly is also wrapped with a fuel channel, a square tube running the full length of the assembly. They remain channeled after the assembly is discharged to the spent fuel pool.

I know it is tempting to look for fuel rods, but I wouldn't be looking for 12 ft long intact rods. You are expecting these rods to find a way to get loose of its spacer plates and shroud after an explosion that was strong enough to blow the FHM sky high? I have a hard time accepting that.

 

[shogun338]

Astronuc will the radiation meters the workers have detect if they walk near neutron beams? What is your opinion of the neutron beams that was reported earlier at the plant ?

 

[Astronuc]

Astronuc will the radiation meters the workers have detect if they walk near neutron beams? What is your opinion of the neutron beams that was reported earlier at the plant ?

The radiation detectors could detect some radiation, and certainly gammas. I don't understand the context of 'neutron beams'. I don't know what detectors are involved.

If they were having re-criticality, then that is a serious problem. It would be a significant violation of safety protocols.

 

[TCups]

A 10x10 fuel assembly has individual fuel rods with a top plate and handle assembly, a bottom plate and nozzle, and three spacer plates. All rods are inserted through the spacer plates.

Fuel assemblies are not robust structrures. I have seen results of dropping new fuel assemblies prior to channeling which resulted in significant tamage to rods. They do not tolerate even small twisting or side loads. That is part of the reason each fuel assembly is also wrapped with a fuel channel, a square tube running the full length of the assembly. They remain channeled after the assembly is discharged to the spent fuel pool.

I know it is tempting to look for fuel rods, but I wouldn't be looking for 12 ft long intact rods. You are expecting these rods to find a way to get loose of its spacer plates and shroud after an explosion that was strong enough to blow the FHM sky high? I have a hard time accepting that.

Me too, but there it is. Most of the force of the blast was going upward, pushing on the fuel handling machine. The fuel rods just got carried along for the ride, not blasted skyward. The spacer plates burst when the fuel rods hit the building.

Here's a question. I bet the new fuel rods are more brittle than the spent fuel rods. From what little metallurgy I know, the heating in a nuclear reactor, then cooling in a SFP, and then maybe heating them again in the explosion might make them less brittle. There do appear to be a few fragmented ones, but few if any appear bent.

The odd thing is that we, the lay public, will most likely never know the exact details, unless Astronuc gets busy, goes over there, and gives us the first hand scoop.

Someone tell me about superheated steam as an explosive propellant, please.

Would steam be more likely to cary a heavy piece of equipment skyward than, say, the heat from a hydrogen blast? I know live steam is a special kind of hot gas with a lot of energy density. The only way I can seem to get enough oomph directly under the FHM to launch it like that, mostly in one piece (if my PhotoShop'ed picture is correct) is, perhaps, for the initial hydrogen blast to take out the roof and then, have the superheated steam from the SFP to to launch the FHM skyward immediately following the hydrogen blast. If freeze frames from a shaky video from way far away are sufficiently informative, that may have been what happened.

 

[Cire]

Differential pressure is something to consider for those trying to figure out where things might or might not have moved inside the building during the explosion.

The internal component would experience with some exceptions equivalent pressures across all their surfaces. (flame propagation from one side to the other of the building will have an effect and cause some pressure transients for a few microseconds). However, its the large differential pressures that move things around.

From an engineering prospective the roof's of the damaged building need to be cut out and removed as soon as possible. The solution is to setup a crane system that cables across units 1-4. With a cable drop and a shear/grapple the upper structures can quickly be cut down and transported away. This can be done remotely. This makes the SFP's serviceable and the upper containment structures clear for inspection. It also allows a bucket system to transfer water into the pools. I suspect a large portion of the radiation leaking is from crushed fuel elements in the spent pools leaking out as the pools are overfilled or leak. Unpressurized fire suppression systems that are clearly broken also provide a fluid path into other structures if they're connected to common mains.

For clearing the random iron/steel components a large electromagnet can suck up most of the building infrastructure that isn't stainless steel. Large chunks of concrete can be picked up with a smaller grapple.

You run a video system on an adjacent cable system similar to those seen at profession stadiums. This let's you do the work safely from a distance. Concrete bases and foundations need to be poured or blocked in for the cranes asap. Debris is transported and put into a storage pit if contaminated until it can be properly disposed of.

A large temporary on site storage pool needs to be constructed asap and a system to move the fuel into that pool setup.

 

[NUCENG]

The video of the blast is taken from the southwest. We see two walls of each reactor building, the south wall in the sun to the right, and the west wall in the shade, to the left. The middle antenna separates one from the other the other in the picture. That is, we see it aligned with the south-west edge of the building. Is that of any help?

I think I've finally figured out what everyone has been calling "antennas" The very tall structures are roughly 200 meters tall. They are the Offgas Stacks. During normal opearion steam and noncondensibles including raqdioactive isotopes are dran of the condensers through steam jet air ejectors and the offgas system then holds the effluent or filters it prior to release theough the offgas stack. During emergencied the Standby Gas Treatment System SBGTS of SGTS maintains a negative pressure in the secondary containment to route all potential leakage through filters and then to the stack for elevated release which increases dispersion of the leakage. If the plant has a hardened vent capability, when the containment is vented it also goes through the filters and stack. Don't need the first function (Offgas) once the turbine is tripped. Of course with the roof blown off the second function is gone. If indeed the containment is breached then the third function is also gone.


Once again, you can design systems to be foolproof. It is unfortunately not possible to make them damnfoolproof.

There is a third elevated stack on the site which has four pipes opened at the top. I believe this is a common release point for the turbine buildings and common fuel pool exhausts. These are additional potential release paths to the environment in other design basis accidents. Elevation aids dispersion and ensures these paths can be monitored to measure any release.

 

[TCups]

Differential pressure is something to consider for those trying to figure out where things might or might not have moved inside the building during the explosion.

The internal component would experience with some exceptions equivalent pressures across all their surfaces. (flame propagation from one side to the other of the building will have an effect and cause some pressure transients for a few microseconds). However, its the large differential pressures that move things around.

So, you seem to be saying that, yes a hydrogen explosion in the upper portion of the building would blow the walls and roof away, but, essentially just drop heavy structures within the inner volume of exploding hydrogen, like the overhead crane, right where they were when the hydrogen exploded (the crane's sidewall supports were blown out), and, also like in the explosion of Building 4, where the FHM is still pretty much just over the SFP and hasn't moved much from the hydrogen blast.

In my proposed scenario, then, a large differential pressure would have to develop from the underside of the FHM, that is, from the SFP. If it were only hydrogen gas in the SFP, then there wouldn't be much pressure differential on the underside of the FHM, but if there were residual hot or boiling water that vaporized from the heat of the blast, explosively expanding from liquid to gas phase, then the FHM would have a pretty big pop gun under it and there would be a very big, vertical blast that would lift it upward into the sky.

Addendum:

Which leads to another line of questioning -- if the water in the SFP of Bldg 3 vaporized and a steam explosion occurred, then why didn't the same thing happen in Bldg 4?

Answer: The hydrogen blast from Bldg 3 came primarily from the drywell containment, not from the hydrogen generated in the SFP. The hydrogen blast from Bldg 4 came from hydrogen generated in the SFP, and this only occurred after most of the water had boiled off and there was little or no water left to convert to steam in the SFP of Bldg 4.

And yet another thought:
The differential pressure from the steam explosion would not tend to blow the fuel rods out, especially if they were in racks bolted to the floor of SFP3. The only reasonably intact fuel rod assembly that came out of the SFP had to be dragged out by the FHM.

 

[Bez999]

@Tcups: In addition, the fuel assembly that would in that scenario be attached to the FHM, would be protected from the blast as it was under water. The FHM would be send skyward with the assemply dragging behind it. Once the machine reaches the zenith of its parabolic track, the attached assembly, hanging off the boom, would swing in its path, centrigugal forces resulting from the FHM "tipping" holding everything in place. When the whole thing lands on top of the building again, the FHM lands first, slightly under an angle. The boom and assembly, still describing an arch, hit the building on their side, i.e. on one side of the channel. Compare taking a packet of spaghetti and swinging it on a piece of string, hitting your kitchen bench. The kinetic energy in the system spills the rods straight out, instead of smashing them. This also explains they are still close together.

 

[AntonL]

Would we have a different picture today if 1000 engineers where mobilized on day one instead of offering this help three weeks later

GE CEO to meet with Japan industry minister to offer support
TOKYO, April 1, Kyodo

The head of General Electric Co., the U.S. manufacturer of reactors at the crisis-hit Fukushima Daiichi nuclear plant, will hold talks on Monday with Japanese industry minister Banri Kaieda to offer support to Tokyo in tackling the ongoing emergency, Japanese officials said Friday.

Jeffrey Immelt, chairman and chief executive officer of the U.S. conglomerate, will meet with the minister together with Hitachi Ltd. President Hiroaki Nakanishi. The Japanese firm is a supplier of reactors to Tokyo Electric Power Co., which operates the atomic power station crippled by the March 11 killer quake and tsunami.

Immelt is also expected to visit the office of the operator known as TEPCO, the officials said.

GE has said it will offer technical assistance to the Japanese government and TEPCO by mobilizing more than 1,000 engineers of Hitachi-GE Nuclear Energy Ltd., a joint venture of the two companies.

The U.S. maker has also offered to provide 10 gas turbine generators to help Japan tackle an energy supply shortage following a request from TEPCO.

==Kyodo

 

[jferello]

I would like to thank everyone for all the information they have posted here, it has been so exciting to learn so much about Nuclear power generation.

1) Astronuc - You are so freakin smart!

2) TCups - Nice forensic work, it was almost like reading a book. I must say though I was getting stressed out seeing all the work you have put into your posts, I could never do all that :)

3) From the information we have currently, is it safe to assume that everything could have been prevented if the plant never ran out of power?

4) If this happened in the states I would hope that we would be able to mobilize tractor-trailer sized generators & have them patched in within 8 hours?

5) Why would it take several days to run electrical connections from the grid back to the plant? Could you not just block off roads, fields etc. and just unspool a giant cable within a few hours?

6) Why do Nuclear plants have emergency hookups? Why not have 'ports' outside the reactor buildings for fire hoses to connect to that would shower the SFP with water? I understand that they need to have a closed system to prevent accidents, but if an accident does occur then they have no recourse it seems.

7) Again I saw some posts about not having the right generator types, 50 vs 60hz or not being able to splice into the system. Why would they not have an emergency hookup area for extra generators, batteries or external power lines? They could have all the transformers, cables, converters etc. to make connecting so much faster.

8) Could someone design a system where when power is lost that the reactor vessel is continually filled with liquid nitrogen? Please don't berate me for this question, I know nothing about interactions between chemicals, I just know that the reactor is very hot and liquid nitrogen is very cold.

9) Do Nuclear plants not have water towers or large storage areas for emergency fresh water, so they can run for a couple days without having to resort to sea water?

10) Finally I keep reading that x amount of radiation is lethal, but I have yet to read anywhere what happens if you get a lethal dose. Like what would happen if someone walked into a room with lethal amounts of radiation and just stood there until they 'died' what would kill them?

 

[AntonL]

a different view looking back towards the view point of the video of explosion 3

 

[biggerten]

I hope this comes through OK, I've been lurking and this is my first post. Thanks to all who have been my unknowing teachers these last few days.

From http://www.tepco.co.jp/en/press/corp-com/release/11040103-e.html

This is the record of the earthquake intensity observed at the lowest
basement of the reactor buildings of Fukushima Daiichi Nuclear Power
Station and Fukushima Daini Nuclear Power Station when the
Tohoku-Taiheiyou-Oki Earthquake occurred approximately at 2:46pm on March
11th, 2011.

This report also contains Maximum Response Acceleration based on
"Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor
Facilities (Revised in 2006)".
We will endeavor to keep collecting as much data as possible and examine
it in more detail.

The comparison between Basic Earthquake Ground Motion and the record of
the earthquake intensity observed at the lowest basement of the reactor
buildings of Fukushima Daiichi Nuclear Power Station and Fukushima Daini
Nuclear Power Station when the Tohoku-Taiheiyou-Oki Earthquake occurred.

【Reference】
Threshold for reactor scram at each unit(The reactor automatically stops
if the intensity of the quake exceeds the threshold.)

Glossary
· Observed Record of Earthquake Intensity
Record that indicates the intensity of an earthquake (Unit: gal)

· Regulatory Guide for Reviewing Seismic Design of Nuclear Power Reactor
Facilities
Revised in September 2006 based on the newly accumulated knowledge on
seismology and earthquake engineering and advanced technologies of
seismic design, this is a regulatory guide in reviewing the validity
of the seismic design of nuclear power reactor facilities.

· Basic Earthquake Ground Motion Ss
A basic earthquake ground motion in seismic design of facility,
stipulated in Regulatory Guide for Reviewing Seismic Design of Nuclear
Power Reactor Facilities

· Maximum Response Acceleration against Basic Earthquake Ground Motion Ss
Assuming Basic Earthquake Ground Motion Ss in the evaluation of the
earthquake-proof safety, this is the Maximum value of the quake of a
building, which is expressed in acceleration

 

[NUCENG]

Regarding the blue flashing light, http://en.wikipedia.org/wiki/Cherenkov_radiation" perhaps ? Is it possible to be created intermittently as claimed in the News Report ?

Rhody...

If the source, as speculated, local criticality it can easily be periodic. Assume the core melt has a small puddle of corium close to critical mass. Adding water to cool the reactor also saupplies a moderator to slow neutrons. As it cools and solidifies it can reach a critical geometry creating which is quickly interruped by boiling off the the water and remelting the corium until it becomes subcritical. Even approaching criticality may be sufficient to create high energy particles capable of visible radiation.

There is an are in Africa which has a very unusual distribution of Uranium isotopes, It is deficient in the portion of U235 found in ores in the rest of the world. It has been suggested that at some time in the distant pass the Earth created a natural reactor due to fluctiations in the water table it depleted the U235. The area is several hundred square miles.

The idea is to mix boron into the corium so it can't approach criticality. It is still necessary to cool it. Once cooled and solidified it may be possible to entomb it dry removing the moderator. That could take a long time.

 

[NUCENG]

Re: http://atomicinsights.com/2011/04/fukushima-nuclear-accident-exceptional-summary-by-murray-e-miles.html about the SFP at Unit 4:

The only shallow section between the spent fuel pool and the reactor is the cattle chute which has the gates people have been discussing. Fuel assemblies are only in the chute while the refueling machine is moving the to the pool or back to the reactor. If the chute fails there is still sufficient water level to keep fuel in the pool and the reactor covered.

 

[NUCENG]

REGARDING A BALLISTIC FUEL HANDLING MACHINE



If there were fuel handling operations in progress and the quake hit, then power failed and the reactor scrammed. It seems plausible that the operators would put the fuel assembly they were handling back in a safe position (if the fuel handling machine could draw power from the backup diesel generators, otherwise not), then get the heck out of there to see what was going on. Think about it -- working up there above the SPF and a big quake hits.

Also, I have absolutely no first hand experience, but from the pictures, the part of the fuel handling machine that handles the fuel assemblies is not a cable or anything like it. It looks like a rigid vertical arm, probably hydraulic, and I would be willing to bet it was built to be very precise, hold the fuel rod assemblies very securely, and put them in exactly the right spot.

If the blast resulted in the same initial trajectory and velocity of the FHM and attached fuel rod assembly, then, the point of impact would be about the same, I should think.

How about it Astronuc? What are the actual mechanics of a FHM and how does it attach to and secure a fuel rod assembly for movement?

Offsite power wasn't lost until the tsunami about an hour after the earthquake. The plant upset (SCRAM) would have halted any fuel moves in progress. It only takes a few minutes to put a fuel bundle back into the spent fuel pool.

The fuel handling machine has a mast with a gripping "grapple" at the lower end. The mast is telescoping for vertical movement. The FHM is mounted on a trasverse for east west and noth south movement between the spent fuel pool and the reactor cavity. It can be positioned directly over any pool or reactor fuel site.

Basically operator lower the mast, grapllet the rod, raise it up to be clear of the other fuel assemblis, moves it to its destination and the lowers it into place. Release the grapple and move to the next step.

Oh yeah, do it very carefully.

 

[NUCENG]

Me too, but there it is. Most of the force of the blast was going upward, pushing on the fuel handling machine. The fuel rods just got carried along for the ride, not blasted skyward. The spacer plates burst when the fuel rods hit the building.

Here's a question. I bet the new fuel rods are more brittle than the spent fuel rods. From what little metallurgy I know, the heating in a nuclear reactor, then cooling in a SFP, and then maybe heating them again in the explosion might make them less brittle. There do appear to be a few fragmented ones, but few if any appear bent.

The odd thing is that we, the lay public, will most likely never know the exact details, unless Astronuc gets busy, goes over there, and gives us the first hand scoop.

Someone tell me about superheated steam as an explosive propellant, please.

Would steam be more likely to cary a heavy piece of equipment skyward than, say, the heat from a hydrogen blast? I know live steam is a special kind of hot gas with a lot of energy density. The only way I can seem to get enough oomph directly under the FHM to launch it like that, mostly in one piece (if my PhotoShop'ed picture is correct) is, perhaps, for the initial hydrogen blast to take out the roof and then, have the superheated steam from the SFP to to launch the FHM skyward immediately following the hydrogen blast. If freeze frames from a shaky video from way far away are sufficiently informative, that may have been what happened.

Spent fuel is more brittle. That is why it remains channelled in the spent fuel pool. NRC has done a lot of studies of fuel rod embrittlement due to radiation and neutron flux.

The definition of explosion is a pressure wave expanding at sonic velocity. The first few frames of the explosion at unit one show a visible expanding semishpere shock wave.

A rapid release of steam creates a similar shock wave/Pressure pulse. Pressure is force. Newton takes over from there.

I don't want to be argumentative, but very good information is readily available about Chernobyl and TMI-2. Japan will need plenty of foreign support and I am pretty confident the information will come out. Heck, the US senate finished all their other mundane tasks and has started to hold hearings. (Sarcasm intended)

One final thought, if the fuel was directly above the blast so it lifted vertically, wouldn't it show heat damage due to the blast itself.

 

[NUCENG]

@Tcups: In addition, the fuel assembly that would in that scenario be attached to the FHM, would be protected from the blast as it was under water. The FHM would be send skyward with the assemply dragging behind it. Once the machine reaches the zenith of its parabolic track, the attached assembly, hanging off the boom, would swing in its path, centrigugal forces resulting from the FHM "tipping" holding everything in place. When the whole thing lands on top of the building again, the FHM lands first, slightly under an angle. The boom and assembly, still describing an arch, hit the building on their side, i.e. on one side of the channel. Compare taking a packet of spaghetti and swinging it on a piece of string, hitting your kitchen bench. The kinetic energy in the system spills the rods straight out, instead of smashing them. This also explains they are still close together.

If it was under water, then the fuel was covered. Where did the hydrogen come from?

 

[razzz]

A cabling system makes the most sense to aid in cleaning (cough) this site up, everything can be done remotely from overhead. Cranes and booms seem to susceptible to Earth's movements.

I read the stack to carry off and partially divert and/or scrub hydrogen and other gases with this design, in the event of an emergency, needs a power source to function properly when called upon.

Can't expect a company's complex to respond with much speed when a great tragedy strikes if they only have one satellite phone on site. Amazing if true esp. in a high tech country such as Japan.

Glad to see committees being assembled and assigned projects: examples might be; units 1, 2, 3, 4 plus pools because that is what it will take, some bright people to figure a way out of this one. Military think tanks come up with decent ideas but it's private industry that carries the load.

Even this board is making more sense on Unit 3 series of events, not that it matters right now.

You might want to take a break and read the responses to a post found elsewhere...
http://www.freerepublic.com/focus/f-news/2698156/posts"