Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Astronuc]

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.

Boric acid is NOT normally used in a BWR - certainly not in the primary system - and not in the spent fuel pool. The spent fuel structure contains boron in boral or boraflex.

Soluble boron in a BWR is introduced only in the case of emergency.

Soluble boron is used routinely in PWRs, and some used enriched boric acid. Some fuel design use enriched boron in ZrB₂ coating on fuel pellets in some fraction of fuel rods.

 

[ernal_student]

And what a stroke of luck that none of those blasted rsj's or roof panels or concrete panels ended up in the pool

With due respect, I have been asking myself, too. I am only a lay person, so all I can do is ask.
I have seen the images of the destroyed roofs on 3 reactors, and if I remember correctly someone had written in this forum that the pools are normally uncovered or just have a plastic cover.
How is it possible that only a few small items have fallen into a pool in a building that has exploded? In one case, did not a machine fall into a pool (I think that had been written in this forum)? There are only very few pictures that have been shown, it seems. How can one trust the information?

 

[MiceAndMen]

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.

Hi Nancy, glad you registered and started posting here. To my mind you're somewhat of a celebrity since you're the only one publicly named so far by the Japanese nuclear industry on their "internet enemies list". If it was me, I would wear that proudly as a badge of honor. I've been critical of some of your analyses on your website, but nevertheless am still glad you decided to join the conversations here. More data is always good and you seem to have some sources. Bringing more info to light will be good going forward in light of the reduced flow of photos coming out of Japan.

Considering the culture of Japanese business I think it's not unusual that some of your sources want to remain anonymous. Anonymous sources of information, however, will generate a fair amount of pushback here. Until their information can be corroborated by other sources they will not be given much weight.

With that said, I also don't think too much can be read into the "leaning tower of Fukushima" evidence presented thus far. The structural integrity of the unit 4 reactor building is a concern considering all the spent fuel in its pool, absolutely, but I don't think grainy long-distance pictures can be relied upon for proof. If the remaining concrete structure on the south side of building 4 came crashing down, taking the SFP with it, that would certainly be a very bad thing. But as of right now I just don't see it happening. It would be nice right about now if we could get a new set of high-res photos taken of the buildings at the Dai-ichi plant. Unfortunately I don't see that happening in the near future, either.

 

[MiceAndMen]

In one case, did not a machine fall into a pool (I think that had been written in this forum)? There are only very few pictures that have been shown, it seems. How can one trust the information?

I think you are referring to the Fuel Handling Machine from Unit 3. It was speculated here for a long time that it had been blown up into the air and landed near the northwest corner of its building. Later on there were photos (from the T-Hawk drone?) that showed it partially in the Unit 3 SFP. The FHM from Unit 4 is still standing and visible in many photos.

If they showed pictures of the Unit 3 SFP and it looked as clean as those from Unit 4 then I think a whole lot of people would jump on the TEPCO conspiracy bandwagon, but what we've seen from the Unit 4 SFP videos isn't all that surprising IMO.

 

[ernal_student]

I think you are referring to the Fuel Handling Machine from Unit 3. It was speculated here for a long time that it had been blown up into the air and landed near the northwest corner of its building. Later on there were photos (from the T-Hawk drone?) that showed it partially in the Unit 3 SFP. The FHM from Unit 4 is still standing and visible in many photos.

If they showed pictures of the Unit 3 SFP and it looked as clean as those from Unit 4 then I think a whole lot of people would jump on the TEPCO conspiracy bandwagon, but what we've seen from the Unit 4 SFP videos isn't all that surprising IMO.

I understand. So I have confused reactor 3 and reactor 4, sorry.

 

[ranchorelexo]

New temps for reactor 3.

http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05090600.pdf

 

[Jorge Stolfi]

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.

How do you get the distance to the back wall? Could there be a wider gap there?

I cannot make out the far edge of the racks (beyond the fallen stair). Shouldn't there be a broader metal "lip" all around the rack (as there is on the near side)? Perhaps there is some large dark piece of debris over the fuel, just beyond the stairs?

Is the water in that part of the pool murkier than the rest (as if there were more bubbles there)? Or is it just that things are farther away in that direction?

 

[coolin'_down]

Thank you all for so much for this site and for all the information. I'm not a scientist but I've been listening to the briefings given by Tepco and NISA trying to keep track of the situations at Fukushima NPP. Though the situation is still very worrying and the many crude approaches taken by Tepco is surprising, I had never been alarmed enough to warrant posting in this site. To get to the point. Tepco just annouced that they will be putting Hydrazine into the spent fuel pool (I think in #1) to counter corrosion, but I read on wikipedia that Hydrazine is also used as rocket fuel! Is Hydrozine usually used in NPP?

 

[Jorge Stolfi]

And what a stroke of luck that none of those blasted rsj's or roof panels or concrete panels ended up in the pool,neat

In unit 4 the fuel-handling machine was parked over the spent-fuel pool when the explosion happened. Perhaps it caught most of the roof debris that would have otherwise fallen into the pool.

There is a video taken by a T-Hawk that peeks into one of the service floor "new windows" on the East side of Unit 4, looking at the yellow drywell cap parked near the opposite wall. Given the extension of the damage to walls and roof, there seems to be surprisingly little concrete rubble on the service floor.

The wall panels were blasted outwards, so it is no wonder that none is to be found inside. As for the roof,
someone suggestde that it may have been lifted by the explosion largely as a single unbroken sheet, which then fell down diagonally over the north end of the building, slicing through the northernmost row of roof girders and contributing to the damage of the north wall.

 

[rowmag]

Here's what Google Translate gives for the headers

Let me make a stab at improving a little on Google Translate (corrections welcome):

1. Temperature of Water Nozzle N4B
2. RPV base head (upper part)
3. RPV body flange
4.Temperature of lower part of pressure vessel
5. RPV stud-bolt temperature
6. RPV body flange (temperature of lower part)
7. Relief safety valve 2-71D Leakage
8. Relief safety valve 2-71F Leakage
9. Main steam isolation valve 2-86A Leak-off
10. D/W HVH return temperature
11. RPV bellows seal
12. S/C Pool water temperature A
13. S/C Pool water temperature B

 

[MiceAndMen]

In unit 4 the fuel-handling machine was parked over the spent-fuel pool when the explosion happened. Perhaps it caught most of the roof debris that would have otherwise fallen into the pool.

There is a video taken by a T-Hawk that peeks into one of the service floor "new windows" on the East side of Unit 4, looking at the yellow drywell cap parked near the opposite wall. Given the extension of the damage to walls and roof, there seems to be surprisingly little concrete rubble on the service floor.

The wall panels were blasted outwards, so it is no wonder that none is to be found inside. As for the roof,
someone suggestde that it may have been lifted by the explosion largely as a single unbroken sheet, which then fell down diagonally over the north end of the building, slicing through the northernmost row of roof girders and contributing to the damage of the north wall.

In the underwater SFP video, I think the metal staircase is from the fuel handling machine. It looks like a complete set of stairs with a handrail, not like it was separated from something else. The vertical distance seems to be appropriate for accessing some parts of the FHM.

 

[Jorge Stolfi]

Here is a rough lineout of the stacking in the pool, as much as can be gleaned from the two released videos.

The "round thing" may be an enclosure within the SFP that holds a fuel transportation cask while loading and unloading. That would be another version of the square concrete enclosure visible in the far left corner of the SFP in the photo of an unidentified japanese reactor (Unit #5?) attached.

Some blueprints/drawings (said to fit Unit #1) show a separate "cask-loading pool" between the equipment pool and the elevator shaft. Presumably in Units #2--#4 that separate pool was replaced by a smaller enclosure within the SFP.

 

[Jorge Stolfi]

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.

Your sketch shows 30*(7+7+12+12+10)+40 = 1480 slots for fuel assemblies; perhaps there are another 60 in the blind corner at right. On the other hand, some slots seem to be empty.

Yet a previous post claims that there were (548 in-use + 1331 spent + 202 new) = 2081 assemblies in the pool. If that number is correct, then we are missing 500 to 600 assemblies. Seems a bit too much for roundoff error...

 

[ernal_student]

named so far by the Japanese nuclear industry on their "internet enemies list".

Where can one see such a list (of one person?)

 

[MadderDoc]

Your sketch shows 30*(7+7+12+12+10)+40 = 1480 slots for fuel assemblies; perhaps there are another 60 in the blind corner at right. On the other hand, some slots seem to be empty.

Yet a previous post claims that there were (548 in-use + 1331 spent + 202 new) = 2081 assemblies in the pool. If that number is correct, then we are missing 500 to 600 assemblies. Seems a bit too much for roundoff error...

Yes indeed. I was going with the figure 1331 assemblies in storage, by March 2011, according to this source.
http://progressivelever.com/2011/03/22/more-on-spent-fuel-pools-at-fukushima/

 

[yakiniku]

New temps for reactor 3.

http://www.tepco.co.jp/nu/fukushima-np/f1/images/032_1F3_05090600.pdf

Do we have corresponding information regarding the pressures and radiation levels in reactor 3?

Would someone be able to comment at what temperature would things become a concern? The values look high but what is considered 'okay', 'normal' or 'abnormal'?

 

[AntonL]

Your sketch shows 30*(7+7+12+12+10)+40 = 1480 slots for fuel assemblies; perhaps there are another 60 in the blind corner at right. On the other hand, some slots seem to be empty.

Yet a previous post claims that there were (548 in-use + 1331 spent + 202 new) = 2081 assemblies in the pool. If that number is correct, then we are missing 500 to 600 assemblies. Seems a bit too much for roundoff error...

it is 1331+202 = 1533 fuel rods
548 in use is included in 1331

 

[Jorge Stolfi]

Yes indeed. I was going with the figure 1331 assemblies in storage, by March 2011, according to this source.
http://progressivelever.com/2011/03/22/more-on-spent-fuel-pools-at-fukushima/

OK, so the 1331 figure includes both in-use and spent. But what about the new assemblies? Several sources give "1331 + 204 new = 1535", e.g.

http://www.ken-zo.com/wp-content/uploads/METI Japan-challenges_full.pdf

It is quite possible that they got it wrong too. But google finds >20,000 hits for Fukushima Daiichi 1535...

 

[MiceAndMen]

Where can one see such a list (of one person?)

A Japanese news story from 27 April says TEPCO doesn't like what Nancy has on her website.
http://www.asahi.com/english/TKY201104260122.html

This is like Sony trying to blame the Anonymous hackers for their own incompetence. Sony was running unpatched web servers without a firewall. Solution? Blame someone else.
http://www.reuters.com/article/2011/05/04/sony-idUSN0422224820110504
http://consumerist.com/2011/05/secu...re-was-obsolete-months-before-psn-breach.html

If Nancy made TEPCO angry then she must be doing something right. That's why I support what she's trying to do on her website even though I disagree with a lot of her analysis and conclusions. I hope she sticks around here as we all try to learn from each other and piece together what has happened, and what is happening at the Dai-ichi plant.

 

[fluutekies]

it is 1331+202 = 1533 fuel rods
548 in use is included in 1331

That are my figures:

1331 used + 204 unused = 1535 assemblies in SFP4

http://www.iaea.org/newscenter/news/tsunamiupdate01.html
[Fukushima Nuclear Accident Update (22 March 2011, 18:00 UTC)]

 

[MiceAndMen]

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.

Your diagram is very good. The similarity to the Oyster Creek SFP blueprint drawings is amazing, right down to the circular "fuel cask drop" in the corner. At least that's what I think it is.

The 2-level spent fuel rack stacking theory is also dead now, thank goodness.

 

[fluutekies]

Fukushima Daiichi Nuclear Power Station First Floor of Turbine Building of Unit 1, May 6th, 2011)

 

[MadderDoc]

How do you get the distance to the back wall? Could there be a wider gap there?

I have not made any real attempt to assess the distance from the racks to the walls at the far end and to the sides. There might well be a wider gap.

I cannot make out the far edge of the racks (beyond the fallen stair). Shouldn't there be a broader metal "lip" all around the rack (as there is on the near side)?

Some close ups of racks show very clearly that a broad lip (with the stamped numbers) is affixed to only one side of the rack.

Perhaps there is some large dark piece of debris over the fuel, just beyond the stairs?
Is the water in that part of the pool murkier than the rest (as if there were more bubbles there)? Or is it just that things are farther away in that direction?

The water is somewhat murky, but working through the videos, my impression was that the murkiness is well-mixed. Naturally, it'll affect the most distant views the most. Some debris might well be hiding there, but no more fuel racks, I think.

 

[|Fred]

named so far by the Japanese nuclear industry on their "internet enemies list". ../...A Japanese news story from 27 April says TEPCO doesn't like what Nancy has on her website.

You may be putting word into the article "TEPCO suspects the blueprint is one of its internal documents, if proven to be genuine,the document is subject to the restrictions imposed under its regulations on nuclear materials protection."

 

[GJBRKS]

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?

If there is a leak in the SFP , bubbles could be formed by cracks in the pool where water leaves and air enters.

My assumption is that the SFP has a leak , and the bubbles could be the symptom

 

[I_P]

I have not made any real attempt to assess the distance from the racks to the walls at the far end and to the sides. There might well be a wider gap.



Some close ups of racks show very clearly that a broad lip (with the stamped numbers) is affixed to only one side of the rack.



The water is somewhat murky, but working through the videos, my impression was that the murkiness is well-mixed. Naturally, it'll affect the most distant views the most. Some debris might well be hiding there, but no more fuel racks, I think.

I get 1480 based on your drawing (including the 4x10 rack) so there would be 2 sets of 30 missing - the ones that would fit in the lower right of your drawing below the control blades. There are two smaller cylindrical objects standing near the large cylinder to its right. What is up with the empty slots shown at the end of the video to the right of the rack of 40?

 

[Curium]

what is quite interesting, is that the melted-looking hole in the roof grid, severely bent/twisted / heat-damaged looking beams, etc are right over spent fuel pool. It is undeniable that beams next to spent fuel pool have some very specific look not replicated anywhere else.

Gundersen made an update to his previous hypothesis about SFP #3.

(1) The orange flash in the video was the Stored Fuel Pool in Unit 3 exploding, because is so localized to the area of the SFP, and because its shape is channeled vertically upward
(2) The fact that the explosion expands outward somewhat to the right, but not to the left, also supports that hypothesis based on the structure of the plant
(3) If the contents of the fuel pool were lifted upward, this cannot have been only an external hydrogen explosion, something exploded in the pool itself
(4) Some other people (not Gundersen himself) suggested that since plutonium melts at a higher temperature than uranium, plutonium could have accumulated in a mass at the bottom of the pool
(5) This could cause a prompt, but "moderated" criticality

Contentions 1, 2, and 3 seem correct on the basis of the evidence. New question is: do hypotheses (4) and (5) make any sense?

Previously it was hard to imagine how an explosion could compress damaged fuel rods into a configuration resulting in criticality. Is the above any more plausible? In any case, something complex must have happened inside Unit 3 to account for what is seen in the videos.

 

[PietKuip]

Tepco just annouced that they will be putting Hydrazine into the spent fuel pool (I think in #1) to counter corrosion, but I read on wikipedia that Hydrazine is also used as rocket fuel! Is Hydrozine usually used in NPP?

Yes, this sounds odd. But hydrazine is used to prevent corrosion of steel parts in steam circuits - it removes oxygen molecules. Concentrations are very low, less than 1 ppm.

Even stranger: vitamin C is recommended as a substitute!
http://pubs.rsc.org/en/Content/Database/HAZ1307001305

 

[MiceAndMen]

Yes, this sounds odd. But hydrazine is used to prevent corrosion of steel parts in steam circuits - it removes oxygen molecules. Concentrations are very low, less than 1 ppm.

About the only good thing you can say about hydrazine is that it's not radioactive. Some formulations are incredibly toxic. One good whiff and your liver is history.

 

[pdObq]

Gundersen made an update to his previous hypothesis about SFP #3.

(1) The orange flash in the video was the Stored Fuel Pool in Unit 3 exploding, because is so localized to the area of the SFP, and because its shape is channeled vertically upward
(2) The fact that the explosion expands outward somewhat to the right, but not to the left, also supports that hypothesis based on the structure of the plant
(3) If the contents of the fuel pool were lifted upward, this cannot have been only an external hydrogen explosion, something exploded in the pool itself
(4) Some other people (not Gundersen himself) suggested that since plutonium melts at a higher temperature than uranium, plutonium could have accumulated in a mass at the bottom of the pool
(5) This could cause a prompt, but "moderated" criticality

Contentions 1, 2, and 3 seem correct on the basis of the evidence. New question is: do hypotheses (4) and (5) make any sense?

Previously it was hard to imagine how an explosion could compress damaged fuel rods into a configuration resulting in criticality. Is the above any more plausible? In any case, something complex must have happened inside Unit 3 to account for what is seen in the videos.

I just had this idea:

a) hydrogen-oxygen mixture ingited in north of building causing deflagration, possibly detonation and shock wave resulting in explosion just as in unit 1

b) for some reason there is an plume of mostly hydrogen sitting above the SFP (i.e. not enough oxygen in the mixture), for example accumumulated under the fuel handling machine.

c) flame front of first explosion a) reaches plume b) which then ignites but burns off rather slow (just deflagration), causing the visible "orange flash" and subsequent smokey mushroom.

That's of course just some speculation by a not-at-all-expert. (But it also includes a possible explanation why fhm3 probably is in orbit .) Would this be plausible?