Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[elektrownik]

About unit 3 from tepco news:

- From 4:18 pm on May 8th to 5:41am on May 10th, we drained the water from
the condenser of the turbine building in Unit 3 as a preparation for the
water injection to the reactor through Feeding Water System.

 

[zapperzero]

* There are still lots of spaghetti-like grey rods among that mess at the NW corner of #3. (Rebar? Shouldn't it have rusted by now?)

Steel wire?

 

[AntonL]

This is big crane under damaged roof, but it is unit 1 not 2

crane? That in my opinion is the high voltage overhead line tower.
[PLAIN]http://k.min.us/inkOf6.JPG

 

[Jorge Stolfi]

Well in order to melt either the Boral metal or the Boraflex plastic, the fuel would have to be not under water. Then it could melt, if the water were gone. But without water it can't go critical.

Would this qualify as a crude nuclear reactor (with steam as neutron reflector/moderator):

EDIT+: Imagine that the water is boiling vigorously, so the steam is heating up as it flows along the hot fuel tubes; but leaves the racks when it is still well below 800 C, so the assembly heads (where no heat is being generated) remain relatively cool and undamaged.

 

[ascot317]

Oooops! http://www.tepco.co.jp/en/news/110311/images/110510_1.zip"

I had feared it would look bad judging by the drone pictures, but this is just terrible.

It's a bit confusing and I yet have figure directions out, but where's the fuel? How sturdy are spent fuel racks normally?

 

[SteveElbows]

Has this series of videos shot inside a Japanese nuclear plant been posted before?

http://www.youtube.com/user/Anjiin#p/u/0/Hv9Ev02fZxg

Its not Fukushima, but I found them fascinating. When they are working on the reactor we can see several items of equipment that are familiar from our Fukushima discussions. And I found the videos numbered 003-005 to be quite fascinating, they are dealing with something radioactive, and we can see how they measure dose, remove lead-lined blankets, hide behind other shielding, and lower this item down to another level. I'm especially fond of the bit near the end where they appear to be randomly hitting it with planks of wood!

 

[Borek]

I had feared it would look bad judging by the drone pictures, but this is just terrible.

It's a bit confusing and I yet have figure directions out, but where's the fuel? How sturdy are spent fuel racks normally?

IMHO it doesn't say anything about the fuel - it can be a complete mess, but it deosn't have to. All we see is that it is covered with rubble. Not a good sign, but IMHO too early to draw far fetched conclusions.

At this stage - especially when planning further actions - it would be better to assume it is a mess, but we won't know before removing the rubble. I guess analysis (chemical/radiological) of water would give much better information about the fuel than this video does.

 

[|Fred]

Point of detail ... in there is a red paper probe with some Japanese writing on it
50 / 60 /70
After the probe is submersed it measure 50..
***
"But where's the fuel? " take your pick
A) below
B) gone (gone where ?)

 

[rowmag]

Has this series of videos shot inside a Japanese nuclear plant been posted before?

http://www.youtube.com/user/Anjiin#p/u/0/Hv9Ev02fZxg

Its not Fukushima, but I found them fascinating. When they are working on the reactor we can see several items of equipment that are familiar from our Fukushima discussions. And I found the videos numbered 003-005 to be quite fascinating, they are dealing with something radioactive, and we can see how they measure dose, remove lead-lined blankets, hide behind other shielding, and lower this item down to another level. I'm especially fond of the bit near the end where they appear to be randomly hitting it with planks of wood!

Looks like they are beating lead shielding sheets into form-fitting shape.

 

[|Fred]

at the center of the picture, could the 2 squares be melted rod ?
[PLAIN]http://i.min.us/ing7TC.jpg

 

[Borek]

When I watched video it looked to me more like top of the fuel assembly, similar to those we have seen in the other SFP. Hard to say how destroyed, if melted and so on.

 

[zapperzero]

I think that's Tsuruga 2, a PWR.

 

[rowmag]

Point of detail ... in there is a red paper probe with some Japanese writing on it
50 / 60 /70
After the probe is submersed it measure 50..

It says "Thermo Label." The dot at 50 means the maximum temperature the label has experienced is 50 degrees or more. No dot at 60 or 70 means the maximum temperature was less than 60. (Once an indicator dot discolors, it is permanent.)

 

[ascot317]

IMHO it doesn't say anything about the fuel - it can be a complete mess, but it deosn't have to. All we see is that it is covered with rubble. Not a good sign, but IMHO too early to draw far fetched conclusions.

At this stage - especially when planning further actions - it would be better to assume it is a mess, but we won't know before removing the rubble. I guess analysis (chemical/radiological) of water would give much better information about the fuel than this video does.

Yeah, I was merely stating that I was unable to identify anything that's "supposed" to be there (except for water xD). I see rubble and I wonder how much the racks can bear.

 

[jlduh]

Anyone use .docstoc? Can you open this link for this document... http://www.docstoc.com/docs/7254461/Reactor-Pressure-Vessel-Issues-Printable-Version

It opened flawless for me...

Adresses various cracks and degradations on RPV and especially PWR's RPV covers...

On this matter, and even if this is a lit bit OFF TOPIC because it's about a PWR MODEL, I wanted to mention this study with impressive cracks and holes (football sized! see the pictures and diagrams) discovered in Davis Besse PWR reactor cover head (Ohio).

http://www.nrc.gov/reading-rm/doc-collections/nuregs/brochures/br0353/br0353r1.pdf

Even if it may be PWR specific, it's interesting to note that it was caused by boric acid leakage (borated water) that has eaten the steel of the head to a point where only the stainless steel cladding inside the cover head was left for structural resistance (3/8 inch!). Any breakage of this (small) remaining thickness would have resulted in a Loss of Coolant (LOCA) accident...

Ok, now back to BWRs:

1) borated water is not normally use inside BWR, but it is used now since the beginning of the accident at Daichi. So a logical question question relates to the effect of this borated water injected in addition to seawater inside BWR reactors (this is "beyond design basis" operation!) for a time that could be long: what could be the impacts on non stainless steel materials for example (corrosion, etc.)?

2) this study shows clearly that as already mentionned before, the place of penetration of various holes, control rods and equipments inside the reactor, with welded parts, is always a weak point and a leakage source. In a BWR, most of these penetrations holes are at the bottom (control rods,etc.).

Something of general interest, because this is NOT PWR or BWR dependant, is also highlightened in this study concerning the reasons why this major damage wasn't discovered before during regular inspection:

Firstly, a lot of the regular inspection planned where... deferred -ending up discovering this much too late!

The staff made several changes to the process to enhance the NRC’s ability to detect declining plant performance, including the specific issues identified at the DBNPS. For example, the review of the event indicated the deteriorating condition had been underway for several years and that the planned inspection, maintenance, and modification activities that could have prevented, or enabled earlier discovery of the condition were frequently deferred.

Secondly the lack of culture of safety at this Davis Besse plant!

Safety culture weaknesses at Davis-Besse were determined to be one of the root causes of the reactor vessel head degradation event.

As we have in France mainly PWR's reactors, I'm wondering what is the situation on this subject of reactors vessels damages with time. I'm going to document on this after reading this NRC document!

 

[|Fred]

thank you BoreK to correct my poorly chosen word "top of the fuel assembly" was the word I was looking for. melted is my assumption

Thank you rowmag, as usual.

 

[clancy688]

Regarding the "scattered fuel" discussion which ended a few pages ago:

https://www.physicsforums.com/showthread.php?p=3270573&highlight=bulldozed+over#post3270573

The NRC-source is also claiming "very high dose rate material" which was lying near Unit 3 and 4 and was subsequently bulldozed over in order to let workers safely work there.
In that case, it's no wonder if we're seeing no heat spots on thermal images.

 

[TCups]

See link below. The energy was there.

You don't need a tube, glass is enough to see what may happen. http://www.youtube.com/watch?v=1_OXM4mr_i0&feature=fvsr Or google for Old Faithful eruption.

See cphoenix posts, he tried to estimate amount of energy in the heated water and they were really impressive https://www.physicsforums.com/showpost.php?p=3250188&postcount=3914 - and even if there were enough to vaporize "only" 2% that still means very large volume of steam. That would be on top of initial destruction done by the hydrogen detonation. So the hydrogen blows the walls/roof, then steam erupts, adds to the destruction and sends a mighty puff into the sky.

Yep, vertical component would be mainly water geyser after hydrogen kaboom.

see earlier posts about exactly this occurring:

https://www.physicsforums.com/showpost.php?p=3230983&postcount=2949

https://www.physicsforums.com/showpost.php?p=3231247&postcount=2973

https://www.physicsforums.com/showpost.php?p=3232329&postcount=3054

 

[jlduh]

Looks like they are beating lead shielding sheets into form-fitting shape.

Yes, videos 3 to 5 are indeed very impressive of real life nuclear waste management from the view points of workers! Not very high tech looking and far from glossy paper nuclear marketing show!

http://www.youtube.com/user/Anjiin#p/u/17/rLIQlJGr-8E
http://www.youtube.com/user/Anjiin#p/u/16/jkI85Mzj7s4
http://www.youtube.com/user/Anjiin#p/u/15/1Dcg2_YGtZ0

Need some base ball skills to flatten lead shielding it seems...

Also video N°16 with the Hair dryer procedure to collect water (probably with some contamination) from this small equipement!

http://www.youtube.com/user/Anjiin#p/u/6/00-8C7T4iO4

 

[MadderDoc]

<..>
See cphoenix posts, he tried to estimate amount of energy in the heated water and they were really impressive https://www.physicsforums.com/showpost.php?p=3250188&postcount=3914
- and even if there were enough to vaporize "only" 2% that still means very large volume of steam.

cphoenix is calculating with a sfp holding 1E4 tons of water, for a Fukushima sfp, 1E3 is closer to fact. So using his method, we'd end up with as much as 20 tons of water evaporated, 30000 m3 of steam 1 bar, or a 30 meter cube.

That would be on top of initial destruction done by the hydrogen detonation. So the hydrogen blows the walls/roof, then steam erupts, adds to the destruction and sends a mighty puff into the sky.

However there are physical limits to the mightiness of 20 tons of water vapour. It's lifting power would be at most 20 tons, equal to its own weight. I think the mighty puff we saw lifted substantially more than that.

 

[imandylite]

Spent Fuel Pool 3 (SFP3)

Youtube Upload

http://www.youtube.com/watch?v=KugIrnThul0"

Its a mess in there - anyone spot fuel rods?

 

[jlduh]

Yeah, I was merely stating that I was unable to identify anything that's "supposed" to be there

Well, anyway i just wonder, considering the mess inside the pool, how some cooling flow can still exist around the fuel rods, assuming they are still below??

A lot of canals and spaces must be completely blocked by dust and debris, creating hotspots, don't you think?

 

[zapperzero]

http://www.youtube.com/user/Anjiin#p/u/15/1Dcg2_YGtZ0

Sorry to go even further off topic, but... I see stuff in that third video that would never fly on a regular construction site. There's one guy who at a point straddles a pulley chain. Some other idiot climbs on the actual container, which is hanging above a two story drop mind you, to remove a hook. A bit after, someone comes from behind the idiot (who's still standing at the lip of the opening, beyond the guardrail) and removes the cable from his safety belt.

During all this, the container they're moving has no lid on... these guys must be selected for demonstrated stupidity, 'cause otherwise they'd realize it's shining out the top as well. Eventually it dawns on them that maybe something ain't quite right so they do the bit with the lead and the hammers. Comedy gold.

Also, where are the counters? I see one on the guy with the camera, one on the guy with the steel neuticles who goes to take contact readings, one hanging on a wall somewhere out of the way and that's all she wrote.

Apparently, one counter per work crew is standard industry practice, not something that only happens in emergencies? Sucks to be them, wouldn't work there for a million bucks a day (I'd be more scared of some idiot dropping something heavy on me than of the radiation, but still).

 

[zapperzero]

However there are physical limits to the mightiness of 20 tons of water vapour. It's lifting power would be at most 20 tons, equal to its own weight. I think the mighty puff we saw lifted substantially more than that.

Where do you get that figure from?

 

[Samy24]

Well, anyway i just wonder, considering the mess inside the pool, how some cooling flow can still exist around the fuel rods, assuming they are still below??

A lot of canals and spaces must be completely blocked by dust and debris, creating hotspots, don't you think?

Interresting is that the radiation in the SFP should come from the reactor core of unit 3 and not from the fuel in the pool.

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

http://www3.nhk.or.jp/daily/english/10_30.html"

 

[jpquantin]

We could also think that this oil is in responsible for the fire but not for the explosion.

The explosion itself could be explained by AntonL's theory (radiolysis) or something else.

Look at the damages on the unit 4 building, particularly regarding the roof. Propane explosion would have done more damages to one part of the roof, don't you think? It seems the explosion was sort of "uniform", fitting well with a spread hydrogen explosion. The wall near the SFP, south of it, seems to have suffered more damages (pillars thrown away). It could be explained by SFP being the source of hydrogen.

Radiolysis can be an explanation, why not considering also ZR oxydation by steam generated by boiling? SFP4 may have boiled several hours before explosion. Time to heat up water to 100°C was roughly 2 days => Mar. 13th 3PM. Explosion was Mar. 15th 6AM. Fuel assemblies are stored in tight space in casks, and steam may accumulate in the top part of it while going up.

By the way, SFP4 was full after last last spray (May 7th); loss rate from previous refilling went back to 56 tons per day. If my data are correct, SFP4 went back from 120 tons per day to 56 tons per day loss.

Last video may also give an indication about gate status (see attachment). At first sight, if correctly identified, it does not seem to have suffered breaks.

 

[~kujala~]

Unit 2:
March 20th 15:05～17:20 Approximately 40 ton seawater injection to the Spent Fuel Pool (SFP) via the Fuel Pool Cooling Line (FPC)
March 22nd 16:07 Injection of around 18 tons of seawater to SFP
March 25th 10:30～12:19 Sea water injection to SFP via FPC


Unit 3:
March 23rd 11:03 ～13:20 Injection of about 35 ton of sea water to the Spent Fuel Pool
(SFP) via the Fuel Pool Cooling Line (FPC)
March 24th 05:35～16:05 Injection of around 120 ton of sea water to SFP via FPC

http://www.nisa.meti.go.jp/english/files/en20110509-1-3.pdf

The levels of radiation detected are almost the same as those detected in April in water samples in the fuel pool of the No.2 reactor.

http://www3.nhk.or.jp/daily/english/10_30.html

Did they have the hoses connected to the same places when injecting sea water to the SFP?

As for the possible maximum levels of sea water injected this document gives the radiation levels of sea water on April 2nd for I-131 at screen/cable pit:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110405e31.pdf

 

[jlduh]

About N°3:

The firm also says the temperature of the plant's Number 3 reactor has been rising this month, and that work to pump water to cool the reactor may be insufficient.

The company says it is installing new pipes at the reactor and hopes to start pumping water through them on Thursday.

http://www3.nhk.or.jp/daily/english/09_28.html

In fact the temps at N°3 decreased in the last days after a high rise that we commented here extensively...

https://spreadsheets1.google.com/sp...ZDbX39YK-iFb0Iw&hl=ja&authkey=CP6ewJkO#gid=40

https://spreadsheets1.google.com/sp...DZDbX39YK-iFb0Iw&hl=ja&authkey=CP6ewJkO#gid=2

Also the water level in RPV has slightly increased. And we are not Thursday, so what did change to explain this drop? They say they increased the flow since last wednesday from 7 to 9 tons/hour. But the temps continued to rise until this WE: inertia?

http://www3.nhk.or.jp/daily/english/10_18.html

 

[MadderDoc]

<..>something occurred to me just now. After the hydrogen explosion there should be an implosion phase - lowering the pressure above water - and that could be enough to start flash boiling.

In theory, perhaps. In this theory, it would seem the implosion phase should follow the explosion, and the expulsion of steam should follow the implosion.

However looking at the video we see that the flash of fire, i.e. the generation of heat, was quite alive and kicking well past the time of the initiation of the massive steam expulsion. Effect cannot precede cause.

 

[MadderDoc]

Interresting is that the radiation in the SFP should come from the reactor core of unit 3 and not from the fuel in the pool.

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

That would be possible, if the explosion opened up a channel for transfer between the core and the pool. It would imply that the explosion breached the RPV and the PCV.

http://www3.nhk.or.jp/daily/english/10_30.html"

 

[clancy688]

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

http://www3.nhk.or.jp/daily/english/10_30.html"

The company says the radioactive substances may have become attached to debris and entered the pool together.

What the heck? Next they'll say that Osama bin Laden dumped them inside the pool.

http://vimeo.com/22586794" is an old video of Arnie Gunderson regarding the measurements of radioactive substances in the water of SFP #4 and TEPCOs explanation that airborne fallout is responsible.
He's calculating that for an amount of 2000 Bq/cm³ in the water of a SFP, you'll need 30 billion Bq/m² fallout - which's way beyond Chernobyl numbers.
(But that doesn't mean that there's been criticality in the SFP - NUCENG calculated that those numbers could have come from very limited fuel damage inside the SFP).

Now, we're having ~300.000 Bq/cm³ Cesium in SFP Unit 4. If the fuel rods are fine and all of that is coming from the air, there must've been fallout of around 4500 billion Bq/m2...

Here are the TEPCO numbers for the pool:

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110510e12.pdf

"Small" iodine numbers, but incredibly high cesium. I'd say that's an indication of major fuel damage inside the pool.
NUCENG can probably tell us if the I2C-Ratio is consistent with spent fuel.

Edit:

Not so sure about the iodine any more...

NUCENG wrote https://www.physicsforums.com/showpost.php?p=3254871&postcount=4200" that the iodine inventory of a 760 MWe core is about 10^15 Bq I131 six months after shutdown. There are ~500 fuel assemblies inside SFP #3, and Unit 3's core is ~500 assemblies big.
But the fuel there is probably much, much older than six months. Furthermore he's guessing, that the SFP has a size of ~2*10^9 cm³.

Inside Unit #3, we have 11.000 Bq/cm³ I131, if we say that half of the pool is filled with debris, then there's about 10^13 Bq inside, around 1% of the total iodine inventory of a six month old core.
But if the fuel's one year old, it should only have 10^9 Bq of iodine left - and the iodine in the water would be 10.000 times the amount of iodine present in the fuel!

If I remember correctly, fuel is stored up to several years in SFPs, so how old would the fuel in SFP #3 possibly be?

 

[Rive]

Interresting is that the radiation in the SFP should come from the reactor core of unit 3 and not from the fuel in the pool.

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

http://www3.nhk.or.jp/daily/english/10_30.html"

There was those steam plumes coming from the reactor, maybe? Iodine, Cesium - both can travel by steam, AFAIK.

The levels of radiation detected are almost the same as those detected in April in water samples in the fuel pool of the No.2 reactor.

Wait, they had taken samples from SFP#2??

 

[Dmytry]

What the heck? Next they'll say that Osama bin Laden dumped them inside the pool.

http://vimeo.com/22586794" is an old video of Arnie Gunderson regarding the measurements of radioactive substances in the water of SFP #4 and TEPCOs explanation that airborne fallout is responsible.
He's calculating that for an amount of 2000 Bq/cm³ in the water of a SFP, you'll need 30 billion Bq/m² fallout - which's way beyond Chernobyl numbers.
(But that doesn't mean that there's been criticality in the SFP - NUCENG calculated that those numbers could have come from very limited fuel damage inside the SFP).

this same very limited fuel damage would of released over a thousand times the observed amount of Cs-137 (given the ratio of i-131 to cs-137 in the old fuel), or alternatively, this fuel damage (and chemistry) would have to be over a thousand times more selective in releasing the iodine versus cs-137 than anywhere else. I'm not saying it proves criticality in sfp4, they might have used contaminated seawater for cooling (but if so, why did not TEPCO give it as explanation?). I'm saying that it doesn't cut it to handwave about chemistry when it is over 1000 times more selective than anywhere else (drains, ditches, ocean, fish bodies...) . If there is something this good at scrubbing out cs-137, that's be WONDERFUL news because they could use it to clean their nasty water.
edit: also, note. 1 mol of i-131 has 1360 times the radioactivity (in Bq) of 1 mol of cs-137, this rules out compounds such as CsI as explanation for the ratio.

 

[MadderDoc]

Where do you get that figure from?

From the scenario, a 1000 tons of water in pool, superheated to about 110 deg C.
This system is unstable, the excess temperature 10 deg. C it is above the boiling point represents the energy available to suddenly vaporize some part of the water.

Water has a heat capacity of 4.18 MJ/ton/degree Celsius, so with 10 degrees and 1000 tons of water, that gives you 4.18*10*1000= 41.8E3 MJ of energy available for vaporization of water.

It takes 2.257E3 MJ/ton to vaporize water, so with 41.8E3 MJ available, this would suffice to vaporize 41.8/2.257 = 18 tons of the water in the pool.

 

[PietKuip]

I don't recall seeing mention of the data published on April 23rd by the Center for the Promotion of Disarmament Non-Proliferation Japan. It contains data for a number of radioactive isotopes that might be interesting from the CBTO Takasaki station in Gunma:

http://www.cpdnp.jp/pdf/110427Takasaki_report_Apr23.pdf

http://www.ctbto.org/verification-regime/featured-stations/types/radionuclide/rn38-takasaki-japan/page-1-rn38/

I had a closer look at those data now.

The ratio of I-134 to I-137 is almost constant (almost always between 0.85 and 0.90), so there do not seem to be too many typos in those numbers.

The table contains some short-lived isotopes like Te-129 with its 70 minute half-life. But it is present because of Te-129m, which has a 34 days halflife. Generally, the tables show Te-129 activity at about half that of Te-129m. Except for March 15, when it is only 10 %. This could be a typo?

There is also I-132 with its 2.28 hour lifetime. It is the daughter of Te-132 (3.27 day halflife). Generally, the I-132 activity is about half that of Te-132. The largest deviation from that is March 16, when I-132 is listed with a higher activity than Te-132.

The ratio of I-131 to Cs-132 is rather variable. Probably this depends on rain etcetera. But the data point for I-131 on March 22 does not seem reliable.

So what is wrong with the Japanese? Why don't they make plots like the German test ban monitoring people do? Why not provide some interpretation?

 

[jpquantin]

"That just doesn't happen" under normal circumstance when the pool is cooled,
and H2 and O in solution quickly recombine, but
[PLAIN]http://k.min.us/invwtS.JPG

https://www.physicsforums.com/attachment.php?attachmentid=35318&d=1304876672" Light Water Reactor Hydrogen Manual by Allen L Camp

Wouldn't it also happen in BWR cores then? Boiling water, high radiation would generate lot of hydrogen, which would not recombine (boiling + steam environment). This means cores would generate a lot of hydrogen, a lot more than observed, don't you think?

BTW same for Zirconium oxydation by steam in boiling environment.

 

[StrangeBeauty]

...I never liked the idea of superheating, as there is plenty of objects in the water that should easily help to start local boiling (see http://en.wikipedia.org/wiki/Boiling_chips - that's all about rough surface) and remove excess heat. ...

(all this in reference to SPF4)
Isn't another problem with the superheating scenario the fact that the site was experiencing almost constant aftershocks of varying degrees throughout this time period which would have created disturbances in the water which, along with the many nucleation sites mentioned by Borek, would inhibit/prevent superheating?

 

[GJBRKS]

Interresting is that the radiation in the SFP should come from the reactor core of unit 3 and not from the fuel in the pool.

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

http://www3.nhk.or.jp/daily/english/10_30.html"

http://img39.imageshack.us/img39/705/containment.jpg

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf

"Steam being quenched from the primary vessel into the torus under high pressure would act as a rocket and could cause vessel displacement"

Has the idea that the full top of the unit 3 RPV was blown off already been debunked ?

It would be consistent with the 1 atm pressure reading

[URL]http://i705.photobucket.com/albums/ww51/Moshpet/Exploded-veiw.jpg[/URL]

source : http://www.abovetopsecret.com/forum/thread693571/pg2#pid11221435

 

[Rive]

Has the idea that the full top of the unit 3 RPV was blown off already been debunked ?

There are still living personnel on site, after a month. Such damage would make that site like Chernobyl -> some seconds at work, and then run for safety...

 

[mrcurious]

Also heard on radio that they are going to try feeding water through a different line at Unit 3 later today, due to the rising temperatures there, since merely increasing the flow rate through the current one is not working, suggesting that the water is not getting where it needs to go for some reason.

It has been suggested salt buildup (from the seawater injection period) at the bottom of the RPV could be insulating corium that deposited there from the partial melting.

 

[|Fred]

Has the idea that the full top of the unit 3 RPV was blown off already been debunked ?
http://www.abovetopsecret.com/forum/thread693571/pg2#pid11221435

This non sense has been ruled out in march.

 

[Jorge Stolfi]

Isn't another problem with the superheating scenario the fact that the site was experiencing almost constant aftershocks of varying degrees throughout this time period which would have created disturbances in the water...?

It occurred to me that *IF* the situation depicted below occurred in an SFP, and *IF* it led to the occurrence of some chain fission, then the water level would be unstable and could start to oscillate. Namely

water level inside assemblies rises --> moderation of neutrons increases --> chain fission increases --> fuel heats up --> steam pressure inside the assemblies rises --> water inside assemblies get pushed down

I presume that if water is boiling inside the assemblies the pressure there would be higher than atmospheric, since the top support plates and the assembly head impede the flow somewhat. Since it would take some time for the extra heat of fission to travel from the fuel to the cladding, the pressure within the assemblies would oscillate in sync with the water level but with some delay --- i.e., the push would be stronger on the way down --- tending to amplify the oscillation rather than to oppose it.

EDIT In fac,t the water level may start oscillating even if there is no chain reaction at first, just from the delay of heating and boiling the water. However, as the top of the wave gets some distance above the surviving boral, then the chain reaction should restart, no?

 

[TCups]

Interresting is that the radiation in the SFP should come from the reactor core of unit 3 and not from the fuel in the pool.

How is it possible that the explosion at unit 3 could "extract" fuel from the core to the pool?

http://www3.nhk.or.jp/daily/english/10_30.html"

Aren't cesium and iodine volatile components that would travel with the vented steam? It seems to me (lay opinion) that this is entirely consistent with steam venting from the reactor vessel into the primary containment (damaged lines or vessel?) and then into the SFP3 (ie, through the fuel transfer chute).

As for the superheated water being very unstable, heck yes -- but the hypothesis was that the "critical" moment of superheating was immediately followed by the steam explosion, and that the explosion and venting of the contents within the primary containment was, in fact, the "last straw" impetus for the steam explosion that caused that criticality.

Is it also possible that criticality occurred, the water/steam was ejected from the SFP, and the contamination with cesium and iodine occurred either as a consequence of the criticality in the SFP or after the pool was refilled? Maybe. A lot of steam was still leaking at the apparent location of the transfer chute after the explosion.

Irrespective of the exact cause initiating the steam explosion, an open connection from the primary containment of Unit 3 to the contents of SFP3 seems to be supported by the water analysis, right?

 

[~kujala~]

I'm not saying it proves criticality in sfp4, they might have used contaminated seawater for cooling (but if so, why did not TEPCO give it as explanation?).

They did:

It said the radioactive materials detected in the latest check could have come from seawater sprayed into the pool to cool the reactor.

http://www.asahi.com/english/TKY201104300099.html

Now the really interesting question is are they going to admit this might also have happened in SFP 2 and SFP 3 but in a larger scale. It's a possibility if the hoses for SFP 4 and SFP 2&3 sprayings were located on different places. But not the only theory.

But if they admit it they must also admit that their calculations concerning the leak into the sea might be heavily underestimated. Which might be the problem?

 

[Jorge Stolfi]

http://www.youtube.com/user/Anjiin#p/u/15/1Dcg2_YGtZ0

Sorry to go even further off topic, but... I see stuff in that third video that would never fly on a regular construction site.

From various reports that I have read, it seems that many nuclear plant workers are temporary people "from all walks of life, bartenders etc.", often unemployed or in financial straits; with no special training or previous construction work experience, hired for a very short time and trained to do a very specific task only. Thus it is not surprising if they are clumsy, inefficient and unsafe when faced with an unforeseen event --- such as a stuck crane hook.

 

[jlduh]

http://img39.imageshack.us/img39/705/containment.jpg

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Containment%20Structures.pdf

"Steam being quenched from the primary vessel into the torus under high pressure would act as a rocket and could cause vessel displacement"

Has the idea that the full top of the unit 3 RPV was blown off already been debunked ?

It would be consistent with the 1 atm pressure reading

[URL]http://i705.photobucket.com/albums/ww51/Moshpet/Exploded-veiw.jpg[/URL]

source : http://www.abovetopsecret.com/forum/thread693571/pg2#pid11221435

The analysis this guy is giving is wrong based on the picture on which he is drawing the supposed reactor, simply because he places it at the wrong place! The reactor is normally centered in the middle of the North/South axis (it's normally offset towards the East on the East/West axis) , but the part of the picture where he is drawing the circle is completely offset to the North side.

See there is no metallic structure over the place where he is drawing the circle, while this remaining structure from the roof is present in the middle of the building after the explosion.

http://www.netimago.com/image_198661.html

I'm not saying anything about the actual condition of the reactor (but at least it seems that some sensors for temps are still working!) but for sure the stuff the guy is showing is NOT the remains of the reacto because it's clearly at the wrong place!

 

[GJBRKS]

The analysis this guy is giving is wrong based on the picture on which he is drawing the supposed reactor, simply because he places it at the wrong place! The reactor is normally centered in the middle of the North/South axis (it's normally offset towards the East on the East/West axis) , but the part of the picture where he is drawing the circle is completely offset to the North side.

See there is no metallic structure over the place where he is drawing the circle, while this remaining structure from the roof is present in the middle of the building after the explosion.

http://www.netimago.com/image_198661.html

I'm not saying anything about the actual condition of the reactor (but at least it seems that some sensors for temps are still working!) but for sure the stuff the guy is showing is NOT the remains of the reacto because it's clearly at the wrong place!

Things are at the wrong place in a lot of places ...

Thought so allready , good to have that cleared up

 

[clancy688]

Has the idea that the full top of the unit 3 RPV was blown off already been debunked ?

One thing that hasn't been mentioned:

D/W radiation sensors are at the top of the containment, near the cap. They wouldn't give any data, not even bogus data, if that part of the reactor would be gone.

 

[mrcurious]

Things are at the wrong place in a lot of places ...

Thought so allready , good to have that cleared up

You're referencing information from a ufo-magiccrystals-NWO-aliens conspiracy site. There may be some useful info posted there but I wouldn't trust the dialogue.

 

[razzz]

Here's the link to the PDF at the NRC's site: http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/prv.pdf"

First post here. I've been reading this thread since around the #350th post and I'd like to thank all the contributors. I've learned an incredible amount about nuclear physics and the engineering of nuclear reactors.

Keep up the good work. Back to lurking...

I guess it's just me that couldn't get to that .pdf. Thanks for the link.