Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[JustGuessing]

Has anyone seen the stills lifted from this video that seems to show the top of a reactor vessel sitting at a 45 degree angle?

 

[AntonL]

Groundwater at nuclear plant 'highly' radiation-contaminated: TEPCO
TOKYO, April 1, Kyodo

More signs of serious radiation contamination in and near the Fukushima Daiichi nuclear power
plant were detected Thursday, with the latest data finding groundwater containing radioactive
iodine 10,000 times the legal threshold and the concentration of radioactive iodine-131 in
nearby seawater rising to the highest level yet.

Radioactive material was confirmed from groundwater for the first time since the March 11 quake
and tsunami hit the nuclear power plant on the Pacific coast, knocking out the reactors' key cooling
functions. An official of the plant operator Tokyo Electric Power Co. said, ''We're aware this is an
extremely high figure.''

The contaminated groundwater was found from around the No. 1 reactor's turbine building, although
the radiation level of groundwater is usually so low that it cannot be measured.

Japanese authorities were also urged to consider taking action over radioactive contamination outside
the 20-kilometer evacuation zone around the plant, as the International Atomic Energy Agency said
readings from soil samples collected in the village of Iitate, about 40 km from the plant,
exceeded its criteria for evacuation.

The authorities denied that the seawater and soil contamination posed an immediate threat to human
health, but the government said it plans to enhance radiation data monitoring around the plant on the
Pacific coast, about 220 km northeast of Tokyo.

According to the government's nuclear safety agency, the radioactive iodine-131 at a concentration
of 4,385 times the maximum level permitted under law has been detected in a seawater sample
collected Wednesday afternoon near the plant, exceeding the previous high recorded the day before.

In Tuesday's sample, the concentration level was 3,355 times the maximum legal limit.

Hidehiko Nishiyama, a spokesman for the Nuclear and Industrial Safety Agency, acknowledged there
is a possibility that radiation is continuing to leak into the sea, adding, ''We must check that (possibility) well.''

He reiterated that there are no immediate health concerns as fishing is not being conducted in the
designated evacuation zone stretching 20 km from the plant and radioactive materials will be
diluted by the time seafood is consumed by people.

Still, the nuclear regulatory body said it has decided to add another three areas located 15 km offshore for monitoring.

Tokyo Electric said it is likely that the high level of contamination in seawater has been caused by water
that has been in contact with nuclear fuel or reactors, but how it flowed to the sea remains unknown.

The No. 1, No. 2 and No. 3 reactors at the plant are believed to have suffered damage to their cores,
possibly releasing radioactive substances, while the fuel rods of the No. 4 reactor kept in a spent fuel pool
are also believed to have been exposed at one point, as the reactors lost cooling functions after the March 11 quake and tsunami.

In Vienna on Wednesday, Denis Flory, IAEA deputy director general and head of the agency's nuclear safety
and security department, said readings from soil samples collected in Iitate between March 18 and March 26
''indicate that one of the IAEA operational criteria for evacuation is exceeded (there).''

In response to the IAEA, Japan's Chief Cabinet Secretary Yukio Edano said Thursday the government may
implement measures, if necessary, such as urging people living in the area to evacuate, if it is found that
the contaminated soil will have a long-term effect on human health.

Nishiyama said at a press conference in the afternoon that the agency's rough estimates have shown
there is no need for people in Iitate to evacuate immediately under criteria set by the Nuclear Safety Commission of Japan.

''The radiation dose of a person who was indoors for 16 hours and outdoors for eight hours (
and continued such a lifestyle) would be about 25 millisieverts, which is about half the level
which requires evacuation based on the commission's criteria,'' he said.

The commission explained that domestic criteria are based on measurements at radiation in the air, and not the soil.

In another effort to prevent radioactive dust from being dispersed from the plant, where masses of
debris are strewn as a result of explosions, Tokyo Electric initially planned to conduct a test
spraying of a water-soluble resin on Thursday, but postponed the plan due to rain.

An official said rain would have slowed down the work and made it difficult to gauge the effects of the resin spraying.

The utility firm known as TEPCO is considering when to conduct the work, at the south and west sides
of the No. 4 reactor. A total of 60,000 liters will be sprayed over a period of two weeks.

TEPCO also tried to remove contaminated water filling up some of the reactors' turbine buildings and
tunnel-like trenches connected to them. But given the large amount of water, authorities
are having difficulty finding places to store it.

TEPCO has been pouring massive amounts of water into the reactors and spent nuclear
fuel pools at the plant as a stopgap measure to cool them down, because serious damage
to fuel rods from overheating could lead to the release of enormous amounts of
radioactive materials into the environment.

However, the measure is believed to be linked to the possible leak of radiation-contaminated
water from the reactors, where fuel rods have partially melted.

Removal of the water at the turbine buildings is believed to be essential to restoring the
vital functions to stably cool down the reactors and the spent nuclear fuel pools.

On Thursday afternoon, a ship provided by U.S. forces carrying fresh water to cool
down the reactors docked on the coast of the plant site to help the mission of water injection.

==Kyodo

each day - from bad to worse

 

[Demidrol]

We've been taking some air samples here in Finland, with
I wonder if anybody else is doing anything similar, and if someone would have better information on the fuel/reload strategy used in the accident reactors.

I am also interested in

 

[JustGuessing]

I've attached one such still image to this post.

 

[TCups]

Has anyone seen the stills lifted from this video that seems to show the top of a reactor vessel sitting at a 45 degree angle?

I have seen the video, but I am far from convinced that the plug is 45º askew from the top of the reactor containment at Unit 3.

It was not the overhead crane that fell in the SFP3, it was the fuel handling equipment.

The steam may be venting from a slot-like structure (the fuel transfer chute) on the north side of the SFP3

I believe these may be the stills from the video in question (my screen captures). Please correct me if not so.

Question for someone who knows:
Is the reactor plug (or the segments that make up the reactor plug) held in place only by gravity when the reactor is operating?

 

[jlduh]

To Justguessing:

the top cover of the pressure vessel (big and yellow) shown in this video is the one of reactor No4 and there is nothing abnormal to see it here because the reactor was on maintenance, so the top cover was removed with no fuel in the core. I was talking about reactor No3 where i have the impression to see something ressembling strangely to a cover of pressure vessel."the top cover was removed with no fuel in the core" did i say?

(well, are we sure that there was no fuel in the core at No4 by the way? We know that it was down but if my understanding of operations is right, when refuelling they just change maybe one third of the fuel, no?

Could it be possible that there was still fuel physically in the open core when the accident happened? So in this case this fuel may be in the same situation than in the other reactor with a decay rate much more advanced of course, because shut down before tsunami. IS IT POSSIBLE? Then of course it would have been fully under the water at the moment of the tsunami but then what happened after if water leaked from pool? It could have been hot too, don't you think? Could this explain why there is so much damage on building No4, even at the low stages of the building? Didn't we conclude to quickly that the reactor was OFF while some fuel was still inside?

TCUPS: try with an other browser maybe, it works perfectly here (don't know for other members?).

 

[timeasterday]

It was not the overhead crane that fell in the SFP3, it was the fuel handling equipment.

The photos you posted seem to show an empty, or nearly empty SFP. The high-res photos that recently came out look like the fuel handling equipment went over the north side of the building. But I don't see any evidence of equipment going into the pool. Maybe I am looking at it wrong.

EDIT: or maybe the green color I am seeing in the SFP is the handling equipment. I saw some other green equipment around the north side and thought that was it.

 

[JustGuessing]

It is this grab with the time code 10:12:11 I'm interested in.

 

[timeasterday]

It is this grab with the time code 10:12:11 I'm interested in.

I think that is some of the normal testing or equipment rigs. Someone posted a shot a while back of the equipment floor from the past and there were lots of these big round things around the floor which I assume are different rigs for diagnostics or repair, or something.

EDIT: here is the post with the photo of a plant floor: https://www.physicsforums.com/showpost.php?p=3210916&postcount=1344

 

[JustGuessing]

The top right corner of the 10:12:11 image look like the rings of the vessel to me.

 

[jlduh]

TCUPS I try to reload the picture showing the "something like a cover pressure vessel in reactor 3" through the "attach" function of the forum, maybe it's better for you?

Ok it's attached as thumbnail but it's smaller than my original...

 

[timeasterday]

TCUPS I try to reload the picture showing the "something like a cover pressure vessel in reactor 3" through the insert image function of the forum, maybe it's better for you?

I think that is part of the overhead crane system. The two large beams of the crane are directly below this feature (and the feature seems to be right in the middle of the beams - maybe it is part of the drive motor assembly of the crane).

 

[hbjon]

There have been comparisons of the Titanic to this disaster. Both were 1 in 10,000,000 chance of happening. Both had safeguards that exceded all contingencies. Both relied on seawater pumps to neutralize the damage. Some people were locked in their quarters while here, some people are told to stay in their homes. Both were Icons of technoloy, science, and power. Titanic had a band to calm the nerves, here we have what? What we have learned is that given enough time, mother nature will throw us a great big curveball. And just like the bugs bunny cartoon, we whiff at it 3 times before it hits the catchers mit.

 

[TCups]

All:
The overhead crane was reported to have fallen through the north side of the top of Bldg 3 and then down, crushing the adjacent building below.

The fuel handling equipment is green in color and, I believe, only shuttles over the SFP and core service access whereas the crane goes from side to side of the building, east to west. The crane is used to hoist the plug structure(s) from the primary containment and to lift the drywell cap (the big yellow-orange cap seen sitting out in Bldg 4). The fuel handling equipment is only for lifting the new and spent fuel rod assemblies. The fuel handling equipment never lifts the fuel rods out of the water. They are transferred under water, through the fuel handling chute and into the reactor while submersed.

It has been my conjecture (unconfirmed), from early on, that if a blast occurred in the primary containment of Unit 3, the "weak spot" would be the fuel handling chute gate, not the massive cap. The seals on the gate were pneumatic and powered by electric pumps (no electricity at the time of explosion).

A blast of hot gasses venting explosively through the fuel handling gate would enter the SFP, possibly vaporizing water in the pool and leading to a secondary steam explosion, or possibly igniting a hydrogen blast, as occurred in Unit 1, or both. The depth of the SFP3 would act like an acoustic lens, to focus the force of any blast occurring from the SFP3 upward. Hence, a two component explosion, fireball out the south side, vertical blast upward over the SFP3, not at the plug, and a secondary blast of hydrogen + oxygen causing a blow out of the building

The venting steam would be coming from the gate/chute area, under the plug. The "stuff" in the SFP3 may be the fuel handling equipment on top of the rods.

 

[timeasterday]

All:
The overhead crane was reported to have fallen through the north side of the top of Bldg 3 and then down, crushing the adjacent building below.

If you look at the high-res photos posted earlier, there is an overhead shot of #3 that shows two large beams running east to west, approximately in the middle of the building. These appear to be a meter or more wide and they are parallel just like one would expect in an overhead crane. It could be something else but it sure looks like a crane to me. But I think the rest of your scenario seems very plausible to me.

 

[jlduh]

TCUPS:

The "stuff" in the SFP3 may be the fuel handling equipment on top of the rods.

Do you talk about what I identify on what looks like the cover of the pressure vessel?

To Justguessing: based on the position where it is on the picture, it cannot be -for sure- the part where there are "rings on the vessel". Because it would mean the vessel is heavily tilted towards the external wall, which i don't foresee based on the layout of the building...

http://www.netimago.com/image_184761.html

 

[83729780]

groundwater containing radioactive iodine 10,000 times the legal threshold . . . The contaminated groundwater was found from around the No. 1 reactor's turbine building

According to the government's nuclear safety agency, the radioactive iodine-131 at a concentration
of 4,385 times the maximum level permitted under law has been detected in a seawater sample
collected Wednesday afternoon near the plant, exceeding the previous high recorded the day before.

how can the levels in the open ocean be almost half as much as the levels in a puddle?

 

[Astronuc]

We've been taking some air samples here in Finland, with preliminary results suggesting Cs-134/137 activity ratios of the order of 1,05. Having no idea of what kind of core design they are using at Fukushima, we made some rough calculations of isotopic concentrations of "typical" BWR assembly at different void histories (see example below).

What we're hoping is to try to see, if it would be possible to estimate the extent of core damage based on isotopic ratios of nuclides from different samples. Like, if it would seem that the measured isotopic ratios correspond to the void history in the top of the core rather than the core average, or the burnup in the most powerful assemblies vs. core average etc.

I wonder if anybody else is doing anything similar, and if someone would have better information on the fuel/reload strategy used in the accident reactors.

Based on the attached and assuming 1/4-core reload for unit 1, it has 4 batches with 148 days of operation since 15-Oct-2010. The batch size could be more like 104 up to 120 or so. If it was 1/3 core reload, the batch size would be about 132 assemblies. But they have a low duty and CF. Outage was 25-Mar to 15-Oct.

Data for Unit 2 indicate a discharge of 116 assemblies, which would indiate ~1/5-core reload. Outage was 16-Sep to 15-Dec-2010, so it is 87 days into the current cycle.

Unit 3 data indicate a discharge of 148 assemblies. The outage was from 19-Jun to 25-Oct-2010, and it was 137 days into current cycle.

It's complicated because of the low availability and relatively low CF depending on the unit.

If one assumes about 10 GWd/tU assembly average burnup in each of 3 cycles and about 8 GWd/tU in the fourth, that would be in the ball park. One would have to pro-rate the current cycles.

 

[TCups]

TCUPS:

Do you talk about what I identify on what looks like the cover of the pressure vessel?

To Justguessing: based on the position where it is on the picture, it cannot be -for sure- the part where there are "rings on the vessel". Because it would mean the vessel is heavily tilted towards the external wall, which i don't foresee based on the layout of the building...

http://www.netimago.com/image_184761.html

I see what justguessing is referencing. Yes, if the top of the entire primary containment is in that location, the north west corner of the structure, then there is MASSIVE damage to and displacement of the primary containment, and I believe, a much different picture would have emerged regarding the core contents of Unit 3.

I cannot independently confirm that the crane fell on the adjacent building. One report I read said so. Certainly, it appears something heavy probably fell on it.

One of the north-south rails for the overhead crane can still be seen in the middle of the two tiers of the erect structural columns on the east side of bldg 3. In fact, it probably supported them and kept them upright after the blast(s). The other rail from the west side is still attached to the columns, which have fallen, en bloc, to the ground immediately adjacent to the west wall. The north side of the top floor has been demolished, consistent with a crane being blasted to the north or to the north wall collapsing and dumping the crane out the north side or some combination of those forces. I see "something" in the debris, but I am hard pressed to say it is the overhead crane. If it is, however, and if it straddles the middle of the building (which I doubt) then it would again seem to prove that the plug did not blast upward from the location of the top of the primary containment, IMO.

I do find it likely that the structure on the west side is the end of the overhead crane.

 

[razzz]

I come up with a minimum of 350 tons of uranium needed to load these 4 reactors not counting extra or excess rod assemblies in various states (new and/or used) stored in proximity i.e. Unit 1,2 and 3 spent fuel ponds or whatever other basement broom closets they might be stored in.

How much potential heat in 350 tons of uranium?

 

[Joe Neubarth]

The top right corner of the 10:12:11 image look like the rings of the vessel to me.

The scale of the actual reactor to that debris is way off by a magnitude of four or five.

 

[shadowncs]

Cut from aerial-2011-3-30-0-20-11.jpg - I think it clearly shows the round outline of PRV from unit 4, to the east side of the building.
Wouldn't it make sense to be in the same position in unit 3? Roughly where lots of steam is seen in the same picture over reactor 3
Shot is from March 20.

https://www.physicsforums.com/attachment.php?attachmentid=33804&stc=1&d=1301595313

https://www.physicsforums.com/attachment.php?attachmentid=33805&stc=1&d=1301595313

Edit: don't know how to thumbnail them

 

[razzz]

how can the levels in the open ocean be almost half as much as the levels in a puddle?

It's possible some of the core(s) found a way route to bedrock or their contamination did besides following the overflow channels leading to the sea.

 

[jlduh]

To shadowncs: Yes you are right and this has already been discussed in one of the numerous pages of the thread. The axis of the reactor is in the middle of the building from North to South axis, but it is not in the middle of its building in the East West axis: it is shifted toward the East, the sea and the turbine building.

I repost this drawing that i captured on NHK, it shows it pretty well: it is shifted because the east part of torus is in fact below the connection building which links the reactor building and the Turbine Building.

http://www.netimago.com/image_184770.html

The building N°3 was smoking at one time from two places: above the SFP on the south side, and above the reactor axis defined at the position you describe.

 

[jlduh]

Just for info: it seems the french IRSN is no more publishing any daily report... The last one is from 29 th of March!
http://www.irsn.fr/FR/Actualites_presse/Actualites/Pages/201103_situation_au_japon.aspx#1

WHY?

 

[jensjakob]

Gents,

Inspired by TCups and armed with the new images, I looked at #3, wondering about the possible fuelrods.

Please see attached image.

FR's could easily have been in the equipmentpool, at the NE corner.

A hydrogen explosion could have blasted towards NW.

Take a look at the arrow I drawed, review the pictures, and give me your thoughts.

The truth is out there

Jens Jakob

 

[DSamsom]

No Idea, How much has the pressure increased or how quickly is it rising, and where are they measuring it... the last I heard (Wiki) they thought 1,2 and 3 had cracks in the containment, or was it the pressure vessel I just read.
Anyone know how high the reactor buildings are...(were!) I want to work out how high that concrete went in the blast at number 3.

Here's the graph of reactor-parameters of Unit 1: http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/v3/plot-un1-full.png

Core pressure is now at its highest point since March 11th, >600 kPa. Not a level that a BWR pressure vessel is very used to.

 

[TCups]

THE CRANE DID NOT FALL ON THE ADJACENT BUILDING

The earlier report of damages that the crane had fallen from unit 3 are incorrect. I stand corrected and I am now convinced that I see the entire crane structure, under the roof girders, and over the area of the concrete plug of the primary containment of unit 3. Thanks for pointing that out.

http://i306.photobucket.com/albums/nn270/tcups/DrywellTorus.jpg

 

[Astronuc]

Here's the graph of reactor-parameters of Unit 1: http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/v3/plot-un1-full.png

Core pressure is now at its highest point since March 11th, >600 kPa. Not a level that a BWR pressure vessel is very used to.

The reactor pressure vessel (RPV) normally operates at an internal pressure of 1055 psia (7274 kPa) with 101 kPa outside! The containment is design to hold about 400 kPa, but should be capable of more.

The design pressure for the RPV is about 8.9 MPa = 8900 kPa, and the hydrostatic test pressure is about 1.3 times design or about 11.6 MPa (11600 kPa).


FYI - http://www.ansn-jp.org/jneslibrary/npp2.pdf

 

[hbjon]

I come up with a minimum of 350 tons of uranium needed to load these 4 reactors not counting extra or excess rod assemblies in various states (new and/or used) stored in proximity i.e. Unit 1,2 and 3 spent fuel ponds or whatever other basement broom closets they might be stored in.

How much potential heat in 350 tons of uranium?

That is more than you can shake your baseball bat at. I like to imagine those u235 atoms as miniature pitching machines stuck on high. The molecule h2o is the catchers mit.(boron is a bigger mit). If the ball beans the batter in the mellon, tempers heat up and everyone loses their cool.

 

[AntonL]

Here are the results of sub drain water samples - this really does not look good
Limit I-131 4E-2 ---> Thus Unit 1 x 10000 as https://www.physicsforums.com/showpost.php?p=3221378&postcount=2222"

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110331e18.pdf

 

[jlduh]

EDIT:

The design pressure for the RPV is about 8.9 MPa = 8900 kPa, and the hydrostatic test pressure is about 1.3 times design or about 11.6 MPa (11600 kPa).

oups you are right Astronuc, i mixed up also with the containement normal design pressure. Sorry.

To TCUPS and all: I confirm that what i identified in a previous post as something like the yellow cover of vessel of reactor n°3 doesn't fit further investigation; its size is to small by around 40% (compared to cover of reactor 4 that we see from the roof) and the other views don't confirm the round shape...

The top view seems to confirm as you say that the roof structure that stays in the middle on No3 is hold by what looks to be the crane, just above the reactor axis. So it would mean that:

1- the crane is still there
2- the plug and the covers are still there (but leaking around)

These Hi RES modify a little bit what what we were thinking.

 

[razzz]

Based on the attached and assuming 1/4-core reload for unit 1, it has 4 batches with 148 days of operation since 15-Oct-2010...

Mr. Astronuc, I had my socks and shoes off trying to figure the possible amount of uranium involved while you were posting your figures so I didn't see it. Now that I see it, your attachment more than doubles my amount of known uranium involved between the 4 reactors. I understand some fuel is in various stages of decay thus less potent and I by no means what to understand the inter-workings of a nuke plant but was just trying to get a idea of the energy that could be released esp. in case of fire.

Your pic with totals seems high. Do they really have that much stored in spent fuel ponds? Did Unit 4 actually have those amount of assemblies already loaded?...At least as far as you know.

 

[jensjakob]

So, that could be why radiation in the ocean just goes up and up.

This is IMHO the exits from the turbinebuilding where coolingwater normally exits.

There should be no movement there. But it looks a lot like there is a flow out of these 2 ports, and on the ocean surface a slight oily discoloring is visible.

 

[AntonL]

here some basic facts to the cooling problem and amount of fuel on site

Unit 1
design 460 MWelect 1380MWtherm
400 Fuel elements in core and 292 in SFP
rest heat day 17 - 2.66MW reactor and about 60kW for pool

Unit 2
design 784 MWelect 2381MWtherm
548 Fuel elements in core and 587 in SFP
rest heat day 17 - 4.59MW reactor and about 400kW for pool

Unit 3
design 784 MWelect 2381MWtherm
548 Fuel elements in core (6% MOX since August 2010) and 541 in SFP (?% MOX)
rest heat day 17 - 4.59MW reactor and about 200kW for pool

Unit 4
design 784 MWelect 2381MWtherm
0 Fuel elements in core and 1331spent +200unused in SFP
rest heat day 17 - 0MW reactor and about 2000kW for pool

Total 14.5MW of cooling required

rest heat assuming 100% load at time of accident
in about 2 months the rest heat would be 50% of above
1MW will boil away 1.41 m3/h of water at temperature of 30 degree

Total 14.5MW of cooling required that is 20.5 m3/hour without overflow and spillage--------------------------------------
under control

Unit 5
design 784 MWelect 2381MWtherm
548 Fuel elements in core and 946 in SFP
rest heat day 17 - 4.59MW reactor and about 700kW for pool

Unit 6
design 1100 MWelect 3293MWtherm
764 Fuel elements in core and 876 in SFP
rest heat day 17 - 6.35MW reactor and about 600kW for pool

Your pic with totals seems high. Do they really have that much stored in spent fuel ponds? Did Unit 4 actually have those amount of assemblies already loaded?...At least as far as you know.

Unit 4 has 1331 in SFP plus 200 newly delivered brand new units - reactor is unloaded
I also included my earlier post which estimate the heat load