Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Jim Lagerfeld]

For those with some Japanese, I highly recommend this NHK documentary which screened this week "ネットワ―クで作る放射能汚染地図" - Network Mapping Radiation Contamination".

Part 1 http://www.youtube.com/watch?v=BUltgqsTTGg&feature=related
Part 2 http://www.youtube.com/watch?v=J7dfoqCj5BA&feature=related
Part 3 http://www.youtube.com/watch?v=6H30i_jI_Ys&feature=related
Part 4 http://www.youtube.com/watch?v=bUA6BueVBR8&feature=related
Part 5 http://www.youtube.com/watch?v=lX-in2-KisA&feature=related
Part 6 http://www.youtube.com/watch?v=XPXprWgh5Wk&feature=related
Part 7 http://www.youtube.com/watch?v=stDYKdPUqtY&feature=related

It has some very interesting footage taken, riding along with Environmental Radiation academics who swing into action after the Fukushima accident to take samples and start mapping fallout ahead of official government efforts and before the 20km closure.

Some interesting explanations about the interaction of local geography and weather conditions which shaped the contamination area, including some narrow valleys to the north-west which collected contaminated snow creating some very hot spots.

Part 4 from 5.30 on:

There is some interesting equipment used, including a portable computer unit which overlays a live digital video camera feed with live gamma radiation spectra. Used from a moving car, the unit is used to get some detailed data on the spread of different contaminants.

Part 4 @ 2.30 minutes:

The one thing I noticed overall - while there are many scenes of detailed spectrographic analysis being performed, the only isotopes mentioned are those of iodine and cesium. Even the NHK graphics suggest information on 9 isotopes are being collected at each point via soil analysis, however the other 6 are never named. Anyone able to fill in the gaps?

Part 1 @ 9 minutes:

 

[Gary7]

What transpired on the Reagan was a few hours after the explosion of #3, which happened on the morning of the 14th in Japan, which is the evening of the 13th in the United States.

If you don't believe me, find the records from UTC and we can translate.

The article I linked to earlier clearly states the decontamination occurred on Sunday, two days after the earthquake. Also, the New York Times reported on Sunday March 13th that USS Ronald Reagan encountered radiation. If the events on the USS Ronald Reagan transpired a few hours after the explosion of #3, the New York Times could not have reported on this on the 13th.

http://www.nytimes.com/2011/03/14/world/asia/14plume.html?_r=1

To put this in even finer detail: The explosion at #3 occurred at about 11:01 am on Monday the 14th (Japan time). This would be 9:00pm on the night of the 13th, EST. Given the time it takes for the helicopter to travel to the aircraft carrier, get decontaminated, and then for the aircraft carrier to reposition itself, and then for that information to get to the reporter, and to have him write the copy and send it to the editors for publishing, it would seem that the only way the New York Times could have reported on this on the 13th would be if they were in possession of a time machine.

Since I think this is of some relevance to the explosion at #3, I have invested a bit of time in the details. However, since it has very little value in helping understand the physics of the event, I will be more than happy if the moderators see fit to delete any and all discussion of the so-called "ballistic radiation levels" and "contaminated food and water" of the USS Ronald Reagan.

 

[rowmag]

Very important: If level 0-reference is Top of Active Fuel Unit 3 core uncovery began at about 1600 on 3/11. Because multiple SRVs were cycling and HPCI apparently did not start, the coolant discharged through SRVs was more than RCIC could make up so level continued to drop after RCIC started. It would be assumed they were able to recover level after the time of these graphs or it would have been unit 3 needing to be vented first.

I think you are referring to page 1 of this:

https://www.physicsforums.com/newreply.php?do=newreply&p=3310549

That caught my eye at first too, but then I looked at the following:

http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_2_Chart3.pdf

If you look at pages 3 and 4, you can see what looks like the same
behavior being recorded by a different sensor (?) on a paper strip
chart that has been scanned in. There are two scales at the bottom,
which differ in both offset and scale factor:

原子炉水位 (広帯域) [mm] = Reactor water level (wideband) [mm]
and
原子炉水位 (燃料域) [mm] = Reactor water level (fuel region) [mm]

The zero offsets are different, and I am guessing that the second one
is the one with zero referenced to the tops of the fuel rods. (That
would match TEPCO's labels elsewhere where they report that.)
I think what was shown in the first link above is the "wideband"
(wide area?) scale, whatever that is.

If this is correct, then the Unit 3 fuel rods did not get exposed
on the 11th, at least as far as these charts show.

What do you think?

 

[MiceAndMen]

The zero offsets are different, and I am guessing that the second one is the one with zero referenced to the tops of the fuel rods. (That would match TEPCO's labels elsewhere where they report that.) I think what was shown in the first link above is the "wideband" (wide area?) scale, whatever that is.

If this is correct, then the Unit 3 fuel rods did not get exposed on the 11th, at least as far as these charts show.

What do you think?

This may or may not be relevant, but the attached diagram shows typical GE BWR instrumentation levels. Notice there is a level called "Instrument 0" and all other measurements are relative to that reference level. In this particular diagram "Instrument 0" is not the same as the top-of-fuel level.

The full-size diagram is found on page 117 of this GE BWR Tech Manual:
http://atominfo.ru/files/fukus/023020088.pdf

The right side shows a "narrow range" gauge and a "wide range" gauge. Maybe a similar measurement arrangement is used by TEPCO.

 

[elektrownik]

Interesting: http://www.tepco.co.jp/en/press/corp-com/release/11052004-e.html

In particular, the melting of the fuel pellets inside Units 1 to
4 caused them significant damage. This was followed by a series of
explosions.

 

[jpquantin]

The latest map of radiation detected on site is out. How interesting it is probably depends on when you last looked at it, I was slightly out of date as the last time I looked this map was getting too busy, its a fair bit cleaner again now.

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f1-sv-20110519-e.pdf

Latest additions are from area near reactor 1, various points along the waste water transfer pipes, and areas near the sea.

This map shows that some concrete was measured max 400 mSv/h, and some iron pipes 100 to 230 mSv/h. In a former post (last one I could find was from Astronuc) it was explained that maybe rebars (or whatever) could "catch" I and Cs.

Is it plausible that some material (like concrete and iron) get some I and Cs "on" it, being exposed to radioactive steam before explosions? Why in this case don't we read much more rubbles with these levels of radiation around reactor #3 or 1? If not, where these parts could come from?

 

[NUCENG]

I think you are referring to page 1 of this:

https://www.physicsforums.com/newreply.php?do=newreply&p=3310549

That caught my eye at first too, but then I looked at the following:

http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_2_Chart3.pdf

If you look at pages 3 and 4, you can see what looks like the same
behavior being recorded by a different sensor (?) on a paper strip
chart that has been scanned in. There are two scales at the bottom,
which differ in both offset and scale factor:

原子炉水位 (広帯域) [mm] = Reactor water level (wideband) [mm]
and
原子炉水位 (燃料域) [mm] = Reactor water level (fuel region) [mm]

The zero offsets are different, and I am guessing that the second one
is the one with zero referenced to the tops of the fuel rods. (That
would match TEPCO's labels elsewhere where they report that.)
I think what was shown in the first link above is the "wideband"
(wide area?) scale, whatever that is.

If this is correct, then the Unit 3 fuel rods did not get exposed
on the 11th, at least as far as these charts show.

What do you think?

My comment was based on the first page of:
http://www.tepco.co.jp/nu/fukushima-np/plant-data/f1_6_Katogensho3.pdf

On that chart there is no mistaking the scale.

In plants I have worked at there may be as many as four different zero references.

The first is the elevation (above sea level).
The second is AVZ (Above vessel zero) which measures from the bottom inside of the RPV
The third is TAF which sets 0 at the Top of Actve Fuel.
The fourth is AIZ (Abave Instrumrnt Zero) which basically references level (positive and negative) from the midpoint between the top 2 instrument taps.

The human factors lessoned learned after TMI2i ncluded control room modifications to use one reference. However some plants picked a different one.

So I looked for clues for which one this is. In a typical US plant the top two instrumment taps are around 10 feet apart or about 3000 mm. , that would measure levels between +1500 mm and -1500 mm. F1-3 is slightly bigger so +1800 mm to -1800 mm makes sense. Narrow Range in the graphs then is being based on only the positive half above instrument zero. and they weren't close to core uncovery.

Physically, TAF would typically be around 10 feet or more below this instrument zero reference. Again, -4000 mm on the Wide Range Instrument makes sense for a bigger plant.

I think you are right that they weren't close to TAF yet.

I am still stuck with why F1-3 had so much SRV activity compared to F1-2. It has to be the delay in getting RCIC started. I need to go back and read some of the early press releases. I now remember reading that F1-3 had HPCI running and later tried to switch to RCIC but were unsuccessful.

That too makes more sense now. SRVs were taking more coolant out than RCIC could make up, so they would have switched to the bigger HPCI pump to recover level. HPCI is usually 4-5 times higher capacity. But HPCI uses more steam. As pressure dropped they would want to use the smaller pump to prolong makeup flow.

Anyway, thanks for the catch.

 

[NUCENG]

This may or may not be relevant, but the attached diagram shows typical GE BWR instrumentation levels. Notice there is a level called "Instrument 0" and all other measurements are relative to that reference level. In this particular diagram "Instrument 0" is not the same as the top-of-fuel level.

The full-size diagram is found on page 117 of this GE BWR Tech Manual:
http://atominfo.ru/files/fukus/023020088.pdf

View attachment 35729

The right side shows a "narrow range" gauge and a "wide range" gauge. Maybe a similar measurement arrangement is used by TEPCO.

Nice find. You got it!

 

[jlduh]

This may or may not be relevant, but the attached diagram shows typical GE BWR instrumentation levels. Notice there is a level called "Instrument 0" and all other measurements are relative to that reference level. In this particular diagram "Instrument 0" is not the same as the top-of-fuel level.

The full-size diagram is found on page 117 of this GE BWR Tech Manual:
http://atominfo.ru/files/fukus/023020088.pdf

View attachment 35729

The right side shows a "narrow range" gauge and a "wide range" gauge. Maybe a similar measurement arrangement is used by TEPCO.

WATER LEVELS:

Something is unclear (at least comparing it to data from Daichi) in this manual for reactor water levels I think as they say that for reactors other than BWR/4 model, the "fuel zone range" for reactor water level uses Top OF Fuel (TAF) point as instrument zero (which is what we see in the measurements: 0 is TAF and - is below top of fuel), instead of the "instrument 0" that your refer. This is explained page 112 of the above manual.

In other words:

for BWR/4 ->> Instrument 0 is defined as 516 3/4 inches (13,12m) "above vessel zero" (AVZ) which measures from the bottom inside of the RPV. This "Intrument 0" is then located in an area close to steam dryer at the very top of the vessel (see page 107)

for other models: -->> instrument 0 = Top of Fuel (TAF) FOR READINGS IN THE "FUEL RANGE" (only)

Unit 1 is BWR/3 , Units 2,3,4,5 are BWR/4 and Unit 6 is BWR/5 (with Mark II containment).

But it seems that all the readings we have for all reactors (including BWR/4) use TAF as zero? Which is not consistent with the manual you listed i think?

But maybe they just changed this since the manual was written to have some uniformity between the reactors (that would be a good idea for the operators!).

So be careful, there are maybe other differences between the manual and what is implemented at Daichi?

DETECTION OF HEAD FLANGE LEAK: It seems there is a system to detect the presence of water i between the two O'rings that seals the flange (RPV head/ RPV). There should be an alarm when detected or even a measurement of the leakage (which is collected to a drain). See page 122 of the pdf. But it is indicated page 106 that using this procedure to read the leak rate steam cuts further the inner seal making the leak even worse! Great system...

I don't know but maybe you will see some parameter somewhere in the buch of data showing this information, indicating some possible leakage at the flange...

Do you think there could be a "kind of similar" detection of leakage of steam+H2 from the top cover of the containment vessel?

 

[jlduh]

Interesting: http://www.tepco.co.jp/en/press/corp-com/release/11052004-e.html

Yes this statement is very clear apparently: melting of pellets in 1,2,3 AND 4...

They must state that kind of things with some evidence on hand.

 

[artax]

This map shows that some concrete was measured max 400 mSv/h, and some iron pipes 100 to 230 mSv/h. In a former post (last one I could find was from Astronuc) it was explained that maybe rebars (or whatever) could "catch" I and Cs.

Is it plausible that some material (like concrete and iron) get some I and Cs "on" it, being exposed to radioactive steam before explosions? Why in this case don't we read much more rubbles with these levels of radiation around reactor #3 or 1? If not, where these parts could come from?

From the map it looks like units 1 and 3 ejected 'rubble' that is 300 to 400 mS/Hr. Has anyone speculated yet what this rubble is and why it is contaminated?
What parts of a reactor would be radioactive to this extent? Or are these 'rubbles' piles of concrete containing bits of spent fuel... or would that give much higher reading?

 

[artax]

For those with some Japanese, I highly recommend this NHK documentary which screened this week "ネットワ―クで作る放射能汚染地図" - Network Mapping Radiation Contamination".

Part 1 http://www.youtube.com/watch?v=BUltgqsTTGg&feature=related
Part 2 http://www.youtube.com/watch?v=J7dfoqCj5BA&feature=related
Part 3 http://www.youtube.com/watch?v=6H30i_jI_Ys&feature=related
Part 4 http://www.youtube.com/watch?v=bUA6BueVBR8&feature=related
Part 5 http://www.youtube.com/watch?v=lX-in2-KisA&feature=related
Part 6 http://www.youtube.com/watch?v=XPXprWgh5Wk&feature=related
Part 7 http://www.youtube.com/watch?v=stDYKdPUqtY&feature=related

It has some very interesting footage taken, riding along with Environmental Radiation academics who swing into action after the Fukushima accident to take samples and start mapping fallout ahead of official government efforts and before the 20km closure.

Some interesting explanations about the interaction of local geography and weather conditions which shaped the contamination area, including some narrow valleys to the north-west which collected contaminated snow creating some very hot spots.There is some interesting equipment used, including a portable computer unit which overlays a live digital video camera feed with live gamma radiation spectra. Used from a moving car, the unit is used to get some detailed data on the spread of different contaminants.The one thing I noticed overall - while there are many scenes of detailed spectrographic analysis being performed, the only isotopes mentioned are those of iodine and cesium. Even the NHK graphics suggest information on 9 isotopes are being collected at each point via soil analysis, however the other 6 are never named. Anyone able to fill in the gaps?

Excellent find those,... It would be nice in english.

 

[zapperzero]

Why in this case don't we read much more rubbles with these levels of radiation around reactor #3 or 1? If not, where these parts could come from?

Some rad maps of the premises have been linked to in past comments. Around unit 3 they show significant amounts of contamination.

 

[zapperzero]

Yes this statement is very clear apparently: melting of pellets in 1,2,3 AND 4...

They must state that kind of things with some evidence on hand.

We may have the evidence ourselves. The fuel in SFP #4 (from the first movie) looked damaged to me, some bails seemed to be missing.

Or the evidence may lay in the evolution of water levels in the pool, which we don't really know.

 

[AntonL]

Yes this statement is very clear apparently: melting of pellets in 1,2,3 AND 4...

They must state that kind of things with some evidence on hand.

Guys, don't always analyse word for word and draw conclusion from English press releases. Get a proper English translation from the Japanese text. Furthermore, the subject of the press release is that 1 to 4 will get decommissioned 7&8 shelved and NOT on damage or fault analysis.

 

[westfield]

Just for your information, and as i found this point very important, i just sent a mail to the author of this interview to try to clarify this sentence:

"TEPCO's civil engineering group estimates the maximum tsunami risk and maximum earthquake risk for each power plant site. I was informed the maximum tsunami at the Fukushima Dai-1 site might be 10 meters".

as it was declared in this interview.

By the way, what he is saying in this interview is somewhat different than what he declared a few weeks ago here, saying: "When I was in charge, the thought of a
tsunami never crossed my mind."

http://thescotsman.scotsman.com/world/39The-thought-of-a-tsunami.6741474.jp

Of interest in this second article, this extract with obviously one mistake:



18.7 ft is 5.7m for the max projected tsunami so it's consistent with Tepco study.

But "13 ft high land on which it stands" is non sense as the platform is 10m high...

I'm only guessing of course but perhaps they are referring to the lowest point on the site where the intake infrastructure, some diesel tanks and some other buildings are located which is indicated as O.P. 4000 (Just over 13')

- edit - wow, that seems quite low. If it didn't have the sea-wall there even a big ocean swell would threaten that elevation.

 

[westfield]

Interesting: http://www.tepco.co.jp/en/press/corp-com/release/11052004-e.html

Interesting that they do not rule out restarting Units 5 & 6 in that statement.

 

[AntonL]

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110520e10.pdf][/URL] -From 2:15 pm, May 20th, we changed the amount of water injected to the
reactor pressure vessel of Unit 3 by the feed water system from 9m³/h to 12m³/h.

and remembering that 9m³/h is also supplied through the reactor fire extiguishing system making a total 21m³/h

Unit 3 seems to be worrying Tepco more than they wish to admit right now

[PLAIN]http://k.min.us/iwCuA.JPG

 

[jpquantin]

We may have the evidence ourselves. The fuel in SFP #4 (from the first movie) looked damaged to me, some bails seemed to be missing.

Can you point on SFP4 images where you see damages? Would be interesting to share.

 

[mscharisma]

...
The first is the elevation (above sea level).
The second is AVZ (Above vessel zero) which measures from the bottom inside of the RPV
The third is TAF which sets 0 at the Top of Actve Fuel.
The fourth is AIZ (Abave Instrumrnt Zero) which basically references level (positive and negative) from the midpoint between the top 2 instrument taps.

The human factors lessoned learned after TMI2i ncluded control room modifications to use one reference. However some plants picked a different one.
...

Forgive me if this is nonsense, but NISA has always reported water levels from TAF (starting March 14). Would that be an indication that TAF is the zero point?

http://www.nisa.meti.go.jp/english/files/en20110315-1.pdf

 

[ottomane]

According to the graph above we finally have ice inside of R3.

The data seems to be really trustworthy.

Nevertheless, I don't understand why they increase the cooling effort while temps are falling. What do they know?

 

[~kujala~]

Can you point on SFP4 images where you see damages? Would be interesting to share.

Hello jpquantin,
As you have calculated the loss rates of SFP 4 is it possible that the SFP 4 at some point has overflowed?
When they spray water over the SFP is there any mechanism that prevents it from overflowing except "let's stop the pumps"?

 

[Jorge Stolfi]

I am traveling again; I hope to get back to my plots next week... All the best.

 

[StrangeBeauty]

and remembering that 9m³/h is also supplied through the reactor fire extiguishing system making a total 21m³/h

Unit 3 seems to be worrying Tepco more than they wish to admit right now

[PLAIN]http://k.min.us/iwCuA.JPG[/QUOTE]

According to the graph above we finally have ice inside of R3.

The data seems to be really trustworthy.

Nevertheless, I don't understand why they increase the cooling effort while temps are falling. What do they know?

At 2:33 pm on May 15, we started injecting boric acid through the fire extinction system.

http://www.tepco.co.jp/en/press/corp-com/release/11051503-e.html

Temps start to go down, without increasing flow rate, after adding boric acid starting on the 15th. Is there another scenario besides renewed criticality which makes sense here? (ok, yes, the sensors themselves are all suspect ;)

It is interesting that they continue to increase water injection at this point. Sensor #2 is the only one that went up recently. #6 is not going down much at this point.

Where is all that water going by the way?

 

[ihatelies]

The article I linked to earlier clearly states the decontamination occurred on Sunday, two days after the earthquake. Also, the New York Times reported on Sunday March 13th that USS Ronald Reagan encountered radiation. If the events on the USS Ronald Reagan transpired a few hours after the explosion of #3, the New York Times could not have reported on this on the 13th.

http://www.nytimes.com/2011/03/14/world/asia/14plume.html?_r=1

To put this in even finer detail: The explosion at #3 occurred at about 11:01 am on Monday the 14th (Japan time). This would be 9:00pm on the night of the 13th, EST. Given the time it takes for the helicopter to travel to the aircraft carrier, get decontaminated, and then for the aircraft carrier to reposition itself, and then for that information to get to the reporter, and to have him write the copy and send it to the editors for publishing, it would seem that the only way the New York Times could have reported on this on the 13th would be if they were in possession of a time machine.

Since I think this is of some relevance to the explosion at #3, I have invested a bit of time in the details. However, since it has very little value in helping understand the physics of the event, I will be more than happy if the moderators see fit to delete any and all discussion of the so-called "ballistic radiation levels" and "contaminated food and water" of the USS Ronald Reagan.

You are incorrect.

Read the article from the NYT it says clearly it was written and published online the 13th and published in the paper the 14th of March.

Look here at the Navy announcement referenced in the NYT article:

http://www.cpf.navy.mil/media/news/articles/2011/mar/mar13_C7F_reposition.shtml

It is dated the 14th of March - because that was the local date. The way the NYT was able to reference an article that was published a day later is that they wrote it the night before.

The NYT issued that article on the 13th of March at 11:15 pm which is their normal news deadline for the following day publication.

In these days of tweets, it doesn't take long for the news of something to get out. At that particular time, all eyes in the world were on the effects of the earthquake/Tsunami and the beginning of the reactor crisis. I was watching this happen, real time. The Navy can issue a press report directly from the ship - no "time machine" needed.

The logs would tell that the Reagan experienced the problem shortly after the explosion of #3 and turned and went the other direction. First post of it on this thread is number 93 at 1:45 pm Eastern on the 14th.

And, it has very much value in understanding the physics of the event. There was a cloud of radioactive material that caused an aircraft carrier to abandon its mission and take on another. We need to know what was in that cloud, because that will tell you what happened a few hours earlier, and it will tell you what hit the west coast of North America 4 days later.

Furthermore, despite your wanting to delete all evidence of my posts. The quote about contaminated air and water supplies on the ship comes directly from the articles posted above.
http://ca.news.yahoo.com/uss-ronald-reagan-fought-contamination-amid-effort-aid-20110325-052432-393.html

Quotes from the article reveal that air and water contamination was detected. What they do not say is what kind of particles caused the problem - but they do say "low level radiation" several times, although their actions do not coincide with that assessment:

"The level of contamination in the air made it difficult to conduct accurate checks on people, so Powell took over the ship's barber shop — a poorly ventilated space that protected the air inside and kept the contamination level low enough to conduct accurate "frisks," or tests.

Meanwhile, the ship itself was taking evasive action, trying to move out of the area of the radioactive plume. After about two hours, it succeeded, Powell said.
"And then after that, we just started checking out the helicopters, checking out all the people, put them all in this little tiny room," he said. "It was kind of scary."
...
"At one point, the carrier's commanding officer announced that there was some radiation in the ship's drinking water supply, and "I know everybody went down to the vending machines to grab (a) bottle of water," Duke said."
...
"Cmdr. Ron Rutan, the Reagan's chief engineer who supervised the swabbing of the deck and other surface areas, said such a cleanup was unprecedented.
"I don't know of any aircraft carrier that's ever been contaminated like this," he said."

Here's a picture of them washing down the deck of the carrier - looks to me like more than just a simple rinse off of a couple helicopters.

I clearly said that the "ballistic" comment was from a blog that I can no longer locate - you can take that one with a grain of salt if you want.

 

[etudiant]

The Reagan clearly got indications of more than just an inconsequential amount of contamination, at least imho.
The people who really got exposure, whose experience caused the carrier to alter course, were the crew of the helicopter that went close to the plant. They got the intense scrubbing, as did their machine.
It was interesting that the press release said none of the ship crew was exposed to significant radiation.
That leaves the air crew exposure open, at least afaik.

 

[zapperzero]

http://www.tepco.co.jp/en/press/corp-com/release/11051503-e.html
It is interesting that they continue to increase water injection at this point. Sensor #2 is the only one that went up recently. #6 is not going down much at this point.

Where is all that water going by the way?

Sensor #2 is RPV bottom head. You do not want it to go up. That's where the fuel is, in the best-case scenario. Water is going out of the RPV and into the basement. How does it get there?

 

[zapperzero]

I think summer forest camouflage for an aircraft carrier crew is comedy gold.

But I also wonder, if the deck was heavily contaminated, why aren't those guys at least wearing plastic bags on their feet ala TEPCO electrician crews? Respirators? They each have one, it's part of their firefighting equipment.

Maybe it wasn't that bad after all?

 

[tsutsuji]

http://www.47news.jp/CN/201105/CN2011051801000828.html 　(referring to 2011/05/18 Kyodo news) tells the story of the failed venting attempts at unit 2, based on a report sent to Tepco-related persons :

On March 13th 11 AM two valves were opened, but the pressure did not come down and no rise of radiation was monitored in the environment.

On March 15th 00:02 AM two different valves on another system were opened, but the pressure did not come down.

The rupture disks are supposed to break at 5.3 atmospheres. The containment pressure was 3.8 atmospheres on the first attempt, and 7.4 on the second attempt.

Batteries are required to keep the valves open, and it is feared that the battery power ran out.

The explosion took place at 6:10 AM on March 15th.

The article concludes saying that Tepco is investigating the causes of the venting failures and the connection with the suppression pool damage.

 

[ihatelies]

I think summer forest camouflage for an aircraft carrier crew is comedy gold.

But I also wonder, if the deck was heavily contaminated, why aren't those guys at least wearing plastic bags on their feet ala TEPCO electrician crews? Respirators? They each have one, it's part of their firefighting equipment.

Maybe it wasn't that bad after all?

I wondered that too.

The picture is obviously carefully staged for the photographer, but I'm surprised if they took off gear for a picture.

The only thing we have to go on as far as how bad it was is what they said and what they did.

Like all the other mysteries in this series of events, if they would simply release the data they have of what was in the cloud, then the smart folks here could likely interpret what happened - but for some reason they have chosen not to do that, or at least I haven't seen it.

 

[etudiant]

Aircraft carrier decks are covered with an anti skid compound.
It is almost ideal for trapping crud, whether radioactive or not. So the crew gets lots of experience cleaning the deck. This is probably the first time in Navy history that a deck cleanup made the news.

 

[NUCENG]

Forgive me if this is nonsense, but NISA has always reported water levels from TAF (starting March 14). Would that be an indication that TAF is the zero point?

http://www.nisa.meti.go.jp/english/files/en20110315-1.pdf

It isn't nonsense. Not to make excuses, but that is probably why I jumped to the conclusion that the graphs were referenced to TAF. But looking at the vessel size and typical layout as pointed out here the graphs only make sense if they are based on AIZ instrument zero. The fact that NISA is using a different reference also makes sense since their priority is core uncovery. But it points out why this was a lesson to be learned from TMI2. Unless you are clear about the units you are using you can create confusion and confusion creates mistakes.

 

[Bandit127]

http://www.tepco.co.jp/en/press/corp-com/release/11051503-e.html

Where is all that water going by the way?

At least some of it is turning to steam. Unit 3 has been above 100°C, but at atomospheric pressure for weeks. Water is either going straight through or turning to steam (probably both), but it simply cannot be in the RPV if the temperature and pressure data are to be believed.

I suggest that Tepco are trying to turn a gas cooled reactor vessel back into a water cooled one. With some limited success, looking at the tempertaure trends from 15th/16th May.

 

[ihatelies]

In my opinion the explosion of #3 from the spent fuel pool is much worse for Japan and the rest of the world than if the explosion occurred in the reactor itself.

So, many here have jumped on me about my theory that the explosion of #3 came from the reactor containment. Some argued that is not possible, and that it must have come from the spent fuel pool of #3. Arnie Gunderson thinks the explosion is from the spent fuel pool of #3.

I believe if the explosion came from the spent fuel pool of particularly #3 , but possibly others, it's way worse, and I hope that is not the case.


First, we acknowledge that in both the reactor and the spent fuel has plutonium in it. The plutonium comes from two sources: First it comes as a by product of the fission reaction in the reactor. I don't think that plutonium is a great risk, because the molecules are interspersed in the rod fuel. In a complete catastrophic explosion, it would not travel far from the reactor.

The second source of plutonium is the mixing of finely ground (nanometer) plutonium powder with the uranium in the new fuel rods that were placed into the #3 reactor in August. Alternatively known as MOX fuel, they mix between 6% and 15% plutonium powder in. I believe the Fukushima rods were somewhere in the lower half of this range.

During manufacture, the powder is "sintered" into pellets. What is unclear in everything I have read is whether the sintering melts the powder into solid metal pellets, or whether it simply binds the material into a pellet, but the powder still remains on the inside. Given my knowledge of powder metallurgy it takes a lot of heat and pressure to render powder into solid metal, and I suspect they would not subject the plutonium to enough to completely bind it, for fear of a reaction during manufacturing.

Once the rods are brought to operating temperature in the reactor core, my guess is they reach a high enough temperature to bind the powder completely. I haven't found anything specific on this topic, so if it's been discussed here, or someone can point me to it, then I apologize in advance. If my guess is correct, then even if the reactor core exploded, it would not pose a very widespread damage to the environment - from plutonium at least - because the bound plutonium would be released in relatively large chunks.

However there exists the possibility that new plutonium enriched rods were waiting in the spent fuel pools to be loaded. If my analysis above is correct, these rods would not have their plutonium bound yet, and in the case of an explosion, the nanometer powder could be released.

I guess this is more of a set of questions for discussion rather than a statement. My question would be this: 1. Does anyone know if the plutonium powder is bound into solid metal during the sintering process? 2. Did any of the spent fuel pool contain plutonium enriched rods ready to be loaded? and 3. If so, is this a danger if the #3 spent fuel blew up rather than the reactor?

Again, pardon my ignorance if this has already been discussed thoroughly.

 

[ihatelies]

Aircraft carrier decks are covered with an anti skid compound.
It is almost ideal for trapping crud, whether radioactive or not. So the crew gets lots of experience cleaning the deck. This is probably the first time in Navy history that a deck cleanup made the news.

Yes, it's like truck bedliner material, except thicker. There are also clip rings for chains, and all kinds of other things all over the deck. washdown is normal.

I don't think they scrub it with brushes and soap very often - I can't remember, but it's more than an acre of deckspace.