Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[imandylite]

Video of team working Inside of Reactor Building of Unit 1

http://www.youtube.com/watch?v=1CFZblqvw9s"

 

[MadderDoc]

<..>
Ps: now we have enough pictures to make a drawing about the pool and make some count about the assemblies- at least we will know how many were not seen.

Yes. We appear to have seen enough fuel racks to hold the recorded number of assemblies in the pool. Here is a rough lineout of the stacking in the pool, as much as can be gleaned from the two released videos.

 

[elektrownik]

Unit 3 is 314,5C now, this is really big...

 

[GJBRKS]

Unit 3 is 314,5C now, this is really big...

This morning at 0600 it was 202 C :

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05080600.pdf

Do you have a link to the source ? I can't find it at the usual locations ...

(and somehow TBS decides to zoom in on unit 1+2 , leaving unit 3 off camera ...)

 

[imandylite]

This morning at 0600 it was 202 C :

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05080600.pdf

Do you have a link to the source ? I can't find it at the usual locations ...

(and somehow TBS decides to zoom in on unit 1+2 , leaving unit 3 off camera ...)

Just looking at the stats myself

Link:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05081630.pdf"

 

[MadderDoc]

In above table some RPV temperature is exceeding the design limit of 300^oC.

Please could a kind knowledgeable person translate the headings

Here's what Google Translate gives for the headers, (change in the temperatures over the last week)

1. N4B Water Nozzle Temperature (93.7 --> 202.1 gr.C)
2. RPV bottom head top (122.3 --> 255.6 gr.C)
3. RPV flange body (99.6 --> 310.1 gr.C)
4. Lower temperature pressure vessel (116.5 --> 151.9 gr.C)
5. RPV stud temperature (98.8 --> 253.6 gr.C)
6. RPV flange body Lower temperature (154.6 --> 173.3 gr.C)
7. Relief safety valve 2-71D Leakage (91.3 --> 158.2 gr.C)
8. Relief safety valve 2-71F Leakage (96.9 --> 108.8 gr.C
9. Main steam isolation valve 2-86A Rikuofu (61.2 --> 63 gr.C)
10. D/W HVH return temperature (101.7 --> 157.6 gr.C)
11. Bellows RPV (137.3 --> 208.6 gr.C)
12. S/C Pool A water temperature (40.6 --> 40 gr.C)
13. S/C Pool B water temperature (40.6 --> 40 gr.C)

 

[MadderDoc]

I found this photo somewhere several weeks ago. Google found it again at

http://www.japannewstoday.com/wp-content/uploads/2011/04/FukushimaSpentFuelRodPoolUnit3-1.jpg

By the title, it would seem to be a close-up of the edge of #3's spent-fuel pool, obviously after the explosion, presumably taken by a camera attached to the pump crane. What are those two gray bars at the top left? (They are too smooth and the wrong color to be rebars, and their ends are closed so they do not seem to be conduits.)

I can't see how this motive can be anywhere near the spent fuel pool of unit 3.
It looks more like the edge of a pit or a manhole than a spent fuel pool. For a starter, where's the steel liner?

 

[fluutekies]

[...]
The cooling water is leaking, which means that they are losing boron, and eventually they will run out of boron, at which point cooling could become impossible as non borated cooling water would cause criticality.
The boron in question is not ordinary boron, but enriched boron-10 which is not readily available.

Why should they use enriched B-11? It would be very expensive and scarce. Natural occurring boron contains 20% B-10 with 80% B-11.
Boric acid H₃BO₃, Borax Na₂B₂O₇ and even Boron trioxide B₂O₃ are bulk chemicals and very cheap. (I don't think TEPCO needs high grade qualities anymore ...)

An aqueous solution of the above mentioned chemicals can be prepared either on- or off-site. Really no big deal.

Does anybody know which concentration is needed to effectively absorb neutrons with B to avoid criticality?

 

[MadderDoc]

Why should they use enriched B-11? It would be very expensive and scarce. Natural occurring boron contains 20% B-10 with 80% B-11.
Boric acid H₃BO₃, Borax Na₂B₂O₇ and even Boron trioxide B₂O₃ are bulk chemicals and very cheap. (I don't think TEPCO needs high grade qualities anymore ...)

An aqueous solution of the above mentioned chemicals can be prepared either on- or off-site. Really no big deal.

Does anybody know what concentration is needed to effectively absorb neutrons with B to avoid criticality?

From what I've read, boron is used up to a few thousand ppm in the cooling water.

 

[StrangeBeauty]

This morning at 0600 it was 202 C :

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05080600.pdf

Do you have a link to the source ? I can't find it at the usual locations ...

Just looking at the stats myself

Link:

http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05081630.pdf"

The second doc has more readings. The two temps from the first doc map to column #1 and #4 in the second doc. Column #3 has the 300+ C reading but all readings are climbing -- not a good sign.

 

[clancy688]

One question regarding the SFP #4 video:

There are bubbles rising in the water... where do they come from? Or rather, what's in a SFP that could produce air bubbles?

 

[~kujala~]

Interesting piece of news from Nuclear News concerning the explosion of unit 4:

The building seems to have suffered a hydrogen explosion, but it is possible
that nobody witnessed the event due to a site evacuation prompted by a radiation release from unit 2 on 15 March.

So perhaps nobody has seen the actual explosion?

Nuclear News also offers their alternative explanation:

It may also have been damaged by the explosion at unit 3.

http://www.world-nuclear-news.org/newsarticle.aspx?id=29978

This goes a little bit in the same direction as the https://www.physicsforums.com/showpost.php?p=3289449#post3289449" by AntonL that hydrogen could have been the result of venting in unit 3, except that the explanation of AntonL is better as the explosion of unit 3 and the estimated explosion at unit 4 happened at different time.
At 11:15 JST on 14 March for Unit 3
At 06:00 JST on 15 March for Unit 4
(Wikipedia)

How sure can we be about the time of explosion of the unit 4 if nobody saw it? Could there be even hours of margin in the estimated time and real time if people around there have not been attentive enough?

 

[Jeff_H]

Here's what Google Translate gives for the headers, (change in the temperatures over the last week)

1. N4B Water Nozzle Temperature (93.7 --> 202.1 gr.C)
2. RPV bottom head top (122.3 --> 255.6 gr.C)
3. RPV flange body (99.6 --> 310.1 gr.C)
4. Lower temperature pressure vessel (116.5 --> 151.9 gr.C)
5. RPV stud temperature (98.8 --> 253.6 gr.C)
6. RPV flange body Lower temperature (154.6 --> 173.3 gr.C)
7. Relief safety valve 2-71D Leakage (91.3 --> 158.2 gr.C)
8. Relief safety valve 2-71F Leakage (96.9 --> 108.8 gr.C
9. Main steam isolation valve 2-86A Rikuofu (61.2 --> 63 gr.C)
10. D/W HVH return temperature (101.7 --> 157.6 gr.C)
11. Bellows RPV (137.3 --> 208.6 gr.C)
12. S/C Pool A water temperature (40.6 --> 40 gr.C)
13. S/C Pool B water temperature (40.6 --> 40 gr.C)

Would the rising temp be consistent with a sensor placed just at the boundary between liquid and steam, with a falling liquid level?

 

[MadderDoc]

How sure can we be about the time of explosion of the unit 4 if nobody saw it? Could there be even hours of margin in the estimated time and real time if people around there have not been attentive enough?

There was a webcam, that pretty much nails the time of the explosion to some time between 6 and 7 am on March 15th

 

[clancy688]

Nuclear News also offers their alternative explanation:

It may also have been damaged by the explosion at unit 3.

http://www.world-nuclear-news.org/newsarticle.aspx?id=29978

That's highly implausible in my opinion. Sat images of March 14th (taken a few minutes after the Unit 3 explosion) show no visible damage on north and east side of Unit 4.

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi_march14_2011_dg.jpg

And the roof of Unit 3 plus the debris laying around don't change over the next weeks, so there's been no other explosion after that event.

 

[elektrownik]

About unit 3: 5/8 11:00 314,5C

 

[AntonL]

One question regarding the SFP #4 video:

There are bubbles rising in the water... where do they come from? Or rather, what's in a SFP that could produce air bubbles?

The camera is being boiled - steam bubbles

 

[Dmytry]

Why should they use enriched B-11?

You tell me. France and US flew them 95 and 5 tons of enriched boron 10 a few days in. Not sure how much enriched though.

It would be very expensive and scarce. Natural occurring boron contains 20% B-10 with 80% B-11.
Boric acid H₃BO₃, Borax Na₂B₂O₇ and even Boron trioxide B₂O₃ are bulk chemicals and very cheap. (I don't think TEPCO needs high grade qualities anymore ...)

Well, maybe natural boron would work fine. I too know that the boron is very cheap and readily available and is a common chemical, but I also know that they've been flying it in on airplane for some reason. I don't know if that's because of perfectionism or because you can't dissolve enough natural boron in water to definitely prevent the criticality.

An aqueous solution of the above mentioned chemicals can be prepared either on- or off-site. Really no big deal.

Does anybody know which concentration is needed to effectively absorb neutrons with B to avoid criticality?

Yep, would be good to know for the worst case. It would depend to the fuel burnup. Fresh fuel has a lot of excess reactivity.

edit: see
http://en.wikipedia.org/wiki/Boron#Enriched_boron_.28boron-10.29
i presume that there's some good reason for enriching boron, 'cause it is obviously quite expensive to do isotope separation.

 

[clancy688]

The camera is being boiled - steam bubbles

But they are not coming from the camera... those two for example, they're coming from between the racks.

 

[SteveElbows]

There was a webcam, that pretty much nails the time of the explosion to some time between 6 and 7 am on March 15th

Indeed.

As far as official info about this event, the wording was quite poor and tried to downplay things regarding unit 4, but anyway:

March 14th 04:08 Temperature of pool is 84 degrees C.
March 15th 06:14 It was confirmed that a part of wall in the operation area of Unit 4 was damaged
March 15th 09:38 Fire spotted at unit 4
March 15th 11:00 Fire no longer seen - presume it went out of its own accord

For example of this information being presented, see parts of this document: http://www.nisa.meti.go.jp/english/files/en20110316-4.pdf

OK so they were very late spotting the fire, but they reported the damage pretty much on time, although using misleading language, we only learned how badly 4 was damaged once we saw photos/video.

Given the timing of unit 3 explosion, I do not have an alternative explanation for what happened at unit 4. It happened within within minutes of the explosive sound at suppression chamber of unit 2, but I don't see how those events could be related. Given that the temperature of the pool was reported at 84C about 26 hours before the explosive event, I still blame the pool, even if we can't see any obvious damage to fuel (can there be significant damage that is not visible?)

 

[Dmytry]

Indeed.

As far as official info about this event, the wording was quite poor and tried to downplay things regarding unit 4, but anyway:

March 14th 04:08 Temperature of pool is 84 degrees C.
March 15th 06:14 It was confirmed that a part of wall in the operation area of Unit 4 was damaged
March 15th 09:38 Fire spotted at unit 4
March 15th 11:00 Fire no longer seen - presume it went out of its own accord

For example of this information being presented, see parts of this document: http://www.nisa.meti.go.jp/english/files/en20110316-4.pdf

OK so they were very late spotting the fire, but they reported the damage pretty much on time, although using misleading language, we only learned how badly 4 was damaged once we saw photos/video.

well yea this translation is a largest nuclear understatement since the Chernobyl's 'electrical equipment fire'.

Given the timing of unit 3 explosion, I do not have an alternative explanation for what happened at unit 4. It happened within within minutes of the explosive sound at suppression chamber of unit 2, but I don't see how those events could be related.

People near #2 could of misidentified #4's explosion sound as coming from #2 for example.

 

[Astronuc]

Enriched boron (B-10 > 0.5) is quited common in the nuclear industry. For a given amount of boric acid, it would be preferable to have more B-10 than the natural concentration would give.

 

[Dmytry]

Enriched boron (B-10 > 0.5) is quited common in the nuclear industry. For a given amount of boric acid, it would be preferable to have more B-10 than the natural concentration would give.

but how bad it would be to run out of enriched B-10 ? I imagine it would be fairly easy to calculate what concentration of B-10 in the water would cancel out water's effect as a moderator... then it could be seen if natural boron can achieve this.

 

[rmattila]

but how bad it would be to run out of enriched B-10 ? I imagine it would be fairly easy to calculate what concentration of B-10 in the water would cancel out water's effect as a moderator... then it could be seen if natural boron can achieve this.

It's mainly the matter of controlling pH. If natural boron is used, more boric acid is needed to get the same reactivity effect, and this makes the pH lower. Depending on the acceptable pH limits and the water chemistry used, this might require addition of base chemicals in order to keep the pH high enough for the core materials.

Regarding the units 1-4 at Fukushima, I don't think the disadvantageous water chemistry resulting from suboptimal pH would make the situation any worse than it already is, taking into account the use of seawater etc.

 

[Astronuc]

but how bad it would be to run out of enriched B-10 ? I imagine it would be fairly easy to calculate what concentration of B-10 in the water would cancel out water's effect as a moderator... then it could be seen if natural boron can achieve this.

That's not really relevant. If they needed a certain level of B-10, then they only need 40% the amount of enrich boron then natural boron. In terms of shipping, the choice would be 95 and 5 tons, as opposed to 250 T and 12 T for natural boron.

The idea is to get as much boron into the system ASAP. Enriched boron is preferred because there is more B-10 especially if one is constrained by solubility limit and/or pH.

 

[NUCENG]

this new underwater video of SFP4 certainly seems to rule out that SFP4 boiled dry and Hydrogen produced by overheating fuel rods and, so how did the Hydrogen get into reactor 4 building? In my opinion, only two possibilities remain:
1. Hydrogen being pumped into the building during venting of unit 3. Unit 3 and 4 share a common exhaust stack and there was no power for fans to work to aid the exhaust procedure.
2. Radiolysis of water as perhttps://www.physicsforums.com/showpost.php?p=3287847&postcount=6068"

Do you have any other ideas?

If the venting from unit 3 containment used the hardened vent it was a release of pressure directly to the stack. The off-gas stacks are really just support structures for the exhaust pipes from each unit. The pipes are separate and go all the way to the top of the stack. Even without power to the fans, to get hydrogen to then flow back down the pipe for unit 4 seems less than likely. Pictures of unit 3 seem to show the stack piping is broken at the unit 3 building so after the explosion of unit 3 there may not even have been a way to get hydrogen to the stack from unit 3. Whatever happened in Unit 4 happened after the explosion in unit 3.

If there were enough radiation to make radiolysis a legitimate threat in a spent fuel pool with freshly discharged fuel, it would be a problem for every fuel pool during every refueling outage. That just doesn't happen. And the freshly discharged fuel in SFP4 was at least 4-5 months old.

The latest fuel pool pictures from unit 4 seem to confirm TEPCO reports that there was only minor damage to fuel in the pool. We still haven't seen any reports or evidence of an explosive source in unit 4 other than hydrogen. There doesn't appear to be sufficient damage the fuel in the pool to have released much hydrogen. The stack is not a likely path for hydrogen from unit 3 to unit 4. Nobody has reported any fresh damage to unit 3 from a second explosion there that can explain damage to unit 4.

Meteorite?

 

[SteveElbows]

The second video avoids looking at the damaged racks visible in the first video. Really, you need a sense of scale. How much larger the pool really is than the reactor core. Pool's 20% damaged is a reactor 100% damaged.

You did not demonstrate clearly visible damage of fuel racks in the first video. There could have been damage, but it certainly was not visible in any clear way.

 

[clancy688]

Meteorite?

Osama bin Laden may be another option. He was still alive back in March. Jorge spotted him in the SFP of Unit 4, didn't he...? Chernobyl happened 25 years and we still don't really know yet why the whole reactor went KABOOM.
I don't think we'll find any answers as to what happened in Unit 4 even during the following months and years...

 

[NancyNancy]

Interesting piece of news from Nuclear News concerning the explosion of unit 4:


So perhaps nobody has seen the actual explosion?

Nuclear News also offers their alternative explanation:


http://www.world-nuclear-news.org/newsarticle.aspx?id=29978

This goes a little bit in the same direction as the https://www.physicsforums.com/showpost.php?p=3289449#post3289449" by AntonL that hydrogen could have been the result of venting in unit 3, except that the explanation of AntonL is better as the explosion of unit 3 and the estimated explosion at unit 4 happened at different time.
At 11:15 JST on 14 March for Unit 3
At 06:00 JST on 15 March for Unit 4
(Wikipedia)

How sure can we be about the time of explosion of the unit 4 if nobody saw it? Could there be even hours of margin in the estimated time and real time if people around there have not been attentive enough?

I had someone point out that the time when 4 likely exploded was right before sunlight so any of the cameras running may have been off. There was a fire reported somewhere between 4am and 6am.

 

[clancy688]

I had someone point out that the time when 4 likely exploded was right before sunlight so any of the cameras running may have been off. There was a fire reported somewhere between 4am and 6am.

I discovered some video material of the scene after the explosions. But you can't really see anything:

https://www.physicsforums.com/showthread.php?p=3266278#post3266278

 

[MadderDoc]

http://www.tepco.co.jp/nu/f2-np/f2land/index-j.html

I know it's about Daini, but it is sweet.

 

[NancyNancy]

Interesting. Looking forward to those new images.

Is the building leaning towards the sea-side? Because the pillars on the south side look pretty much intact below the service floor. I don't think the inner structure such as the reactor and sfp are resting on the outside pillars (that's at least what I would hope), so that it wouldn't really matter much if the outer hull of the building is leaning, unless it is going to collapse and stuff falls into the sfp. Or is the whole unit supposed to lean from ground up?

The SFP is somewhat dependent on the building framework. The building instability concerns cited to the media by staff at the plant were that the instability of the building framework is causing concerns about the stability of the SFP.

If you look at the elevation of reactor 1, the blueprint that is floating around.
http://www.houseoffoust.com/fukushima/reactorblueprint.jpg
You see that the SFP is tied into the outside of the containment concrete. It hangs sort of like a window box off of the containment structure. There is a very thin piece of concrete that ties the bottom of the SFP to the outer frame of the building. There is nothing supporting the SFP from below.

The technicians at the plant are citing the instabilities of the structure as a whole as causing worry about the SFP stability. From what I was told by a reliable source in the media is that this is a considerable worry, getting some sort of reinforcement under the SFP is a priority. This was before the building began leaning over.

 

[unlurk]

Chernobyl happened 25 years and we still don't really know yet why the whole reactor went KABOOM.

Some people don't know why, but these are the people who deny the possibility of a criticality accident; or people who believe the accounts of those who do deny that occurrence.

http://en.wikipedia.org/wiki/Criticality_accident

Same story with Fukushima 3.
In my opinion.


BTW
Where did all the "hot" radioactive material around the site come from?
Obviously not from unit four.

 

[Dmytry]

The SFP is somewhat dependent on the building framework. The building instability concerns cited to the media by staff at the plant were that the instability of the building framework is causing concerns about the stability of the SFP.

If you look at the elevation of reactor 1, the blueprint that is floating around.
http://www.houseoffoust.com/fukushima/reactorblueprint.jpg
You see that the SFP is tied into the outside of the containment concrete. It hangs sort of like a window box off of the containment structure. There is a very thin piece of concrete that ties the bottom of the SFP to the outer frame of the building. There is nothing supporting the SFP from below.

The technicians at the plant are citing the instabilities of the structure as a whole as causing worry about the SFP stability. From what I was told by a reliable source in the media is that this is a considerable worry, getting some sort of reinforcement under the SFP is a priority. This was before the building began leaning over.

hmm but did it really begin leaning over?

 

[SteveElbows]

If you look at the elevation of reactor 1, the blueprint that is floating around. http://www.houseoffoust.com/fukushima/reactorblueprint.jpg
You see that the SFP is tied into the outside of the containment concrete. It hangs sort of like a window box off of the containment structure. There is a very thin piece of concrete that ties the bottom of the SFP to the outer frame of the building. There is nothing supporting the SFP from below.

The technicians at the plant are citing the instabilities of the structure as a whole as causing worry about the SFP stability. From what I was told by a reliable source in the media is that this is a considerable worry, getting some sort of reinforcement under the SFP is a priority. This was before the building began leaning over.

There is no doubt that it is a concern, which is why they intend to do something about it.

However, I am really not sure I agree with your description that the pool would not have anything supporting it from below. That could be the case at 4 now due to building damage, but under normal circumstances it looks like there are a variety of other parts of the structure that hold the pool in place, not just the outside wall. Personally I would not use reactor 1 sketch as a guide, but if I do then I see concrete walls below the pool.

As for unit 4 building leaning, I can appreciate that you can judge your sources and we cannot, but there is no way in the world I am going to believe you on this without more proof. There has now been a large volume of complete rubbish spoken on the internet about Fukushima, most of it based on exceedingly poor analysis of photos or videos, especially since the online feed went up. Barely a night now goes by without someone coming on here and claiming they have just seen new explosions, buildings leaning or having new damage, and as far as we can tell so far they are just plain wrong.

You say that your sources were right in the past, perhaps you could give an example of something else they told you about in advance that then came true? Do you have any other photos or anything that can help the case you are trying to make?

 

[Astronuc]

The SFP is somewhat dependent on the building framework. The building instability concerns cited to the media by staff at the plant were that the instability of the building framework is causing concerns about the stability of the SFP.

If you look at the elevation of reactor 1, the blueprint that is floating around.
http://www.houseoffoust.com/fukushima/reactorblueprint.jpg
You see that the SFP is tied into the outside of the containment concrete. It hangs sort of like a window box off of the containment structure. There is a very thin piece of concrete that ties the bottom of the SFP to the outer frame of the building. There is nothing supporting the SFP from below.

The technicians at the plant are citing the instabilities of the structure as a whole as causing worry about the SFP stability. From what I was told by a reliable source in the media is that this is a considerable worry, getting some sort of reinforcement under the SFP is a priority. This was before the building began leaning over.

The SFP does NOT "hang sort of like a window box off of the containment structure." The drawing shows a cross-section of the plant at one plane. The interpretation given (from someone who apparently does not have the appropriate technical background to make a sound judgement) is grossly incorrect. However, there is concern regarding the containment structures of Fukushima units following the earthquake (and subsequent explosions), because they haven't been able to inspect for damage, which could be cracks/leaks.

 

[SteveElbows]

Actually I've just been reviewing the live feed again and I would bet strongly that unit 4 is not leaning, there is simply no indication of leaning at all. If you insist on sticking to the idea that it is leaning, without further proof, please at least ask your 'sources' when this is supposed to have happened, what date did this supposed deterioration to unit 4 happen?

 

[NancyNancy]

Interesting. Looking forward to those new images.

Is the building leaning towards the sea-side? Because the pillars on the south side look pretty much intact below the service floor. I don't think the inner structure such as the reactor and sfp are resting on the outside pillars (that's at least what I would hope), so that it wouldn't really matter much if the outer hull of the building is leaning, unless it is going to collapse and stuff falls into the sfp. Or is the whole unit supposed to lean from ground up?

I have a couple of new images on my website. One of the crane being moved and inserted into the side of the building at the work floor level. Not sure why. Move due to structural worries? Moved so work to shore up the SFP could begin? Needed to inject water directly in the pool?

Also some new images of the leaning reactor 4 along with vertical landmarks to try to figure out the leaning. I mentioned in another post that I received confirmation from the TBS tech crew that it is not an optical illusion of the camera and also from workers at the plant that 4 is leaning over. There is also a building on the seaside side of 4 that connects to the turbine building. This could be impacting the way and how much 4 leans over. There is considerable damage to the walls on the north and south so the other two walls have lost some of their ability to stay upright. The containment concrete is built before the building top but it is slightly offset so the weight of the containment structure weight could be causing some of the sinking and leaning. They have poured in tons of water, the soil around the building could be becoming unstable adding to the sinking. There were previous concerns about the groundwater levels making the NPP buoyant. There was also some concerns about the offset reactor design and tall skinny upper building in the context of the two older reactors at Hamaoka that are identical to the older units at FUKU. The tall skinny buildings along with the offset reactors were cited as increasing the lateral movement of the building. This article talks about the superiority in the design used at the newer units at Hamaoka. I am still trying to find the other article on their site that mentioned the lateral issues with the old units. I lost the link, will post if I find it again. http://www.chuden.co.jp/english/initiatives/eini_nuclearpower/enuc_earthquakemeasures/eear_reactorbuildings/index.html


So you have a reactor building that is floating to an extent, lots of water added to the situation, constant earthquakes and two confirmations that this isn't a camera trick.

Asahi Shimbun article about the floating buildings http://www.asahi.com/english/TKY201104010166.html

Manichi article about bedrock being 46 meters down http://mdn.mainichi.jp/mdnnews/news/20110427p2g00m0dm091000c.html

Study confirming the NPP is on floating mudstone base not bedrock http://www.iitk.ac.in/nicee/wcee/article/9_vol3_733.pdf

info and photos of r4 sinking and the moved crane http://www.houseoffoust.com/fukushima/r4sinking.html

images of yesterday's steam and smoke show http://www.houseoffoust.com/fukushima/May8smoking.html

 

[NancyNancy]

The SFP does NOT "hang sort of like a window box off of the containment structure." The drawing shows a cross-section of the plant at one plane. The interpretation given (from someone who apparently does not have the appropriate technical background to make a sound judgement) is grossly incorrect. However, there is concern regarding the containment structures of Fukushima units following the earthquake (and subsequent explosions), because they haven't been able to inspect for damage, which could be cracks/leaks.

A number of different people who work in various capacities on a daily basis with blueprints and structural issues found it concerning. Of course there is information missing with only having these two elevation views. There appears to be limited reinforcement under the SFP and the people working at the plant are citing structural issues with the pool and the building.

I don't find taking personal swipes at people very useful to the conversation.

 

[MadderDoc]

Something very interesting I just discovered - apparently television images of the Unit 4 explosion / fire.
But it's hard to see anything...

I believe these images were taken from a helicopter on March 16th, the day after the explosion in unit 4. Several snippets from this helicopter overfly exists, on the net ,e.g.


Edit: I believe the shooting time for this footage is about 11 am.

 

[|Fred]

Move due to structural worries?
Do you think that they insert the crane into the side of the building because the building is unstable and it its easier to get the crane into this hole without disturbing anything?

Take a 320 pixel wide picture of a several meters structure, upsample that 1280 pixel and draw 2 pixels wide "reference" ..

http://k.min.us/ileBnu.JPG

Edit by Borek: too wide image replaced by link

edit: ok pictures scaled down
[PLAIN]http://k.min.us/jnvlFs.JPG
[PLAIN]http://k.min.us/jle5bk.jpg

 

[fluutekies]

Madderdoc: "From what I've read, boron is used up to a few thousand ppm in the cooling water."

Astronuc: "Enriched boron (B-10 > 0.5) is quite common in the nuclear industry. For a given amount of boric acid, it would be preferable to have more B-10 than the natural concentration would give."

rmattila: "It's mainly the matter of controlling pH. If natural boron is used, more boric acid is needed to get the same reactivity effect, and this makes the pH lower. Depending on the acceptable pH limits and the water chemistry used, this might require addition of base chemicals in order to keep the pH high enough for the core materials."

I think I got it:
Under normal conditions enriched boric acid H₃BO₃ probably is -even at its much higher price and limited availability- the boron compound of choice in a nuclear power plant: highest concentration B-10, lowest concentration of accompanying elements (only O and H) and high purity due to its multi-step synthesis. And indeed therefore less high-grade NaOH or other base is needed for pH-adjustment.
I assume the purity requirements of the cooling water are very stringent. If the water after refueling/maintenance has to be made boron-free again by ion-exchange, smaller quantities are advantageous, even if the materials are more expensive.

Dmytry: "You tell me. France and US flew them 95 and 5 tons of enriched boron 10 a few days in. Not sure how much enriched though. [...] ... but I also know that they've been flying it in on airplane for some reason. I don't know if that's because of perfectionism or because you can't dissolve enough natural boron in water to definitely prevent the criticality."

I remember that I was astonished when this news hit the press the first or second day of the disaster. But...for me at that time (with LOCA and reported water levels far below top of fuel), reactors 1-3 were written off and the state of emergency started.

rmatilla: "Regarding the units 1-4 at Fukushima, I don't think the disadvantageous water chemistry resulting from suboptimal pH would make the situation any worse than it already is, taking into account the use of seawater etc."

Indeed, this is not a normal, but an emergency situation.
But obviously TEPCO at that time acted as under normal conditions by replenishing their high-grade stocks, hoping to save their assets. IIRC they were very reluctant to use seawater even when they run out of normal water and it took them weeks to admit that they had to write there assets off.

 

[elektrownik]

I think that they move crane to take video of SFP or/and inside building from new point.

 

[AntonL]

If there were enough radiation to make radiolysis a legitimate threat in a spent fuel pool with freshly discharged fuel, it would be a problem for every fuel pool during every refueling outage. That just doesn't happen. And the freshly discharged fuel in SFP4 was at least 4-5 months old.

"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

In https://www.physicsforums.com/showpost.php?p=3287847&postcount=6068" , using above paper I worked out that some 120 to 150kg of Hydrogen could have been developed in SFP-4

Meteorite?

Conspiracy believers would quickly prove that the http://en.wikipedia.org/wiki/High_Frequency_Active_Auroral_Research_Program"

 

[AntonL]

Arnie Gunderson http://vimeo.com/23393101"

also discusses explosion reactor 3

 

[MadderDoc]

Indeed.

As far as official info about this event, the wording was quite poor and tried to downplay things regarding unit 4, but anyway:

March 14th 04:08 Temperature of pool is 84 degrees C.
March 15th 06:14 It was confirmed that a part of wall in the operation area of Unit 4 was damaged
March 15th 09:38 Fire spotted at unit 4
March 15th 11:00 Fire no longer seen - presume it went out of its own accord

Yes, it is and was confusing. I got the impression that for whatever their reason, after the explosion, recurrent fires were at play in unit 4. A striking change of color and shape of some debris hanging out from a hole at 4th floor in the north wall could be the signature of a fire event in that area at some time between March 15th and March 16th.

<..>
Given the timing of unit 3 explosion, I do not have an alternative explanation for what happened at unit 4. It happened within within minutes of the explosive sound at suppression chamber of unit 2, but I don't see how those events could be related.

Independent events do happen all the time, concurrently, but I think it is worth a thought, if there could be some causal relationsship between events in unit 2 and unit 4, since there is this tight coincidence.Following those big pipes along the turbine buildings might be worth a shot. I can't think of anything else connecting the buildings, which might be able to pump up unit 4 with hydrogen from unit 2.

Given that the temperature of the pool was reported at 84C about 26 hours before the explosive event, I still blame the pool, even if we can't see any obvious damage to fuel (can there be significant damage that is not visible?)

Pass. I feel not, but that could be wrong. After seeing the sfp videos, the Tepco theory of a flush of water from the reactor cavity released by an explosion has still credence. However, what exploded, and from where did it come?

 

[I_P]

Looking at the righthand photo posted by MadderDoc above you can see that the buckled upper wall panels are putting strain on the wall and columns below. If the upper portion of the wall were to collapse and pull down the support columns below perhaps this would put additional strain on the fuel storage pool supporting structure. Maybe this is what the concern with unit 4 stability is...

 

[SteveElbows]

I don't find taking personal swipes at people very useful to the conversation.

Well I am afraid that's the risk you take when you post sloppy information as if it was fact. There is nothing wrong with a bit of speculation, but pretending that such things are certain is not good. I also fear that attempts to make your sources sound great will not count for very much here, it does not make up for poor quality evidence. The onus is on you to provide decent evidence, don't complain if the theory is not taken seriously without such evidence.

We have known for a good while that they worry about unit 4 building & the stability of the pool, this emerged back when TEPCO announced their roadmap to bring the site under control. But the press didnt really talk about it as soon as this plan was announced, it went almost unnoticed, until TEPCO themselves started making comments about having to take it easy with the pool spraying, because they were worried about the weight of the water. But then things got more confusing because as soon as they said that, they went on a multi-day marathon where a huge quantity of water was sprayed into number 4. Then they stopped, did not spray at all between april 28th and may 4th, and then sprayed a very large amount of 270t on the 5th, 180t on the 6th and 120t on the 7th. If the pool was hanging by a thread, or the building was starting to lean badly, if they were absolutely afraid that the pool may collapse at any moment, then I doubt they would have risked putting so much water in in one go.

So yes, its a concern, something horrible could happen, but there's no way this disaster requires sexing up by some people drawing dodgy lines on photos and acting like its conclusive proof of anything.

 

[SteveElbows]

Looking at the righthand photo posted by MadderDoc above you can see that the buckled upper wall panels are putting strain on the wall and columns below. If the upper portion of the wall were to collapse and pull down the support columns below perhaps this would put additional strain on the fuel storage pool supporting structure. Maybe this is what the concern with unit 4 stability is...

That photo is a wall that's on the opposite side of the building to the fuel pool.

Personally I don't know exactly what makes them afraid, except to say that in general the building is in poor condition. Perhaps they are worried by what they see when they look into the hole that is lower down on the south side of the building, or the lower holes on the east side,certainly I assume that there is much detail we cannot see from the few photos we have, and that's part of the reason I don't think we have learned very much from all these hours spent (over)studying photos.

 

[SteveElbows]

Yes, it is and was confusing. I got the impression that for whatever their reason, after the explosion, recurrent fires were at play in unit 4. A striking change of color and shape of some debris hanging out from a hole at 4th floor in the north wall could be the signature of a fire event in that area at some time between March 15th and March 16th.

Yes, there was a further fire reported in a useless way that never properly confirmed it:

The fire at Unit 4 occurred (05:45 March 16th) TEPCO reported that no fire could be confirmed on the ground (06:15 March 16th).

http://www.nisa.meti.go.jp/english/files/en20110317-1.pdf