Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Uagrepus]

That looks like some debris in the air, out of focus, close to the lens rather than smoke in the distance. It's completely gone in the next image (both images at 3:44pm):
http://www.tepco.co.jp/en/news/110311/images/110519_1_7.jpg

Yes, the foto seems to be from behind a window (see the grid?), so an insect on it is possible also between 6 of 17 at 15h44 (1) and 7 of 17 at 15h44 (2). I agree, no smoke on the water ...

 

[tsutsuji]

http://www.asahi.com/national/update/0518/TKY201105180230.html provides a diagram with a scenario for unit 1's hydrogen explosion. Hydrogen runs through a damaged part of the RPV into the containment vessel, then through a crack in the containment vessel.

On March 11th, 9:51 PM workers were forbidden to enter the reactor building because of the 290 mSv/h radiation there.

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

13 rhymes with the O.P. +13 m ground floor height at units 5 & 6.

 

[jlduh]

http://www.asahi.com/national/update/0518/TKY201105180230.html provides a diagram with a scenario for unit 1's hydrogen explosion. Hydrogen runs through a damaged part of the RPV into the containment vessel, then through a crack in the containment vessel.

On March 11th, 9:51 PM workers were forbidden to enter the reactor building because of the 290 mSv/h radiation there.



13 rhymes with the O.P. +13 m ground floor height at units 5 & 6.

Yes, except it's foots and not meters...

 

[SteveElbows]

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 How interesting it is probably depends on when you last looked at it, I was slightly out of date as the last time I looked this map was getting too busy, its a fair bit cleaner again now.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

 

[KJones]

Does anyone have any thoughts and/or data that might provide insights re: the possible state(s) of the fuel?

I have heard there is a possibility that when the zircaloy cladding burned, the fuel pellets may have dropped to the floor of the RPV, but are more likely to be spread out, rather than in a molten lump.

Any informed thoughts on this? Thanks.

 

[MiceAndMen]

An interview with former Fukushima plant manager:

http://spectrum.ieee.org/tech-talk/...echalert&utm_medium=email&utm_campaign=051911

Interesting as it provides some sense of what someone very familiar with the plant was thinking when they watched the disaster unfold on tv.

Not a lot of technical specifics, apart from this answer about what safety upgrades were done there in the past:

In this interview Tsuneo Futami does little more than parrot the official TEPCO company line. He says he oversaw core shroud replacement

However it was necessary to work inside the reactor pressure vessels in order to replace a component called a shroud, although we used remote and automatic equipment as much as possible. I led the shroud replacement program of unit 1, 2, 3 and 5 and completed the world’s first shroud replacement in 1998.

Stress corrosion cracking is an aging problem. Some Fukushima Dai-1 reactors exceeded 30 years while I was a superintendent. I put my best effort into replace aging equipment based on preventive maintenance philosophy.

Perhaps he did put his best effort into the replacement projects once they were underway, but saying the replacements were "based on a preventive maintenance philosphy" is not truthful.

Standard TEPCO public relations policy calls for them to claim they undertook core shroud replacement programs as a matter of "preventive maintenance". Yet, the big scandal in 2002 went directly to TEPCO covering up information that the core shrouds in several of their reactors were cracked. They knew about it for years and told no one. After a whistleblower complained to METI, they embarked upon an investigation (in conjunction with TEPCO and after TEPCO fired the whistleblower) that showed several core shrouds were, indeed, cracked. In the end, even that report downplayed the severity of the cracks in the Fukuchima Dai-ichi Unit 2 reactor.

http://cnic.jp/english/newsletter/nit92/nit92articles/nit92coverup.html

It has been confirmed that there are 29 cases of falsification, which were related to damage in many parts of the reactor pressure vessel such as core shroud, jet pump, access hole cover, feed water spurger, on-core monitor housing and others. The NISA and the TEPCO published interim reports on September 13 and 17 respectively, which addressed the 29 suspected cases in more detail. Regarding the cracks detected in the core shroud, according to the report, they had been already found at Fukushima I Unit-1 and Unit-4 in 1993, where the cracks in the middle part of the shroud at Fukushima I Unit-2 in 1994 were reported officially as the first case. The magnitude of the cracks in Fukushima I Unit-2 turned out to be far greater and more serious than the ones announced by the official report. It has also become clear that reactors in Fukushima I Unit 1, 3, and 5 have cracks in each shroud, so the claim that no cracks were found in the core shrouds and that they were replaced as a “preventive measure” is completely false.

(Bolded emphasis mine.)

That is just one website where details of the safety report falsification scandal can be found. There are many others that corroborate essentially the same story.

Whenever I see reference to TEPCO's "preventive measures" claiming some sort of credit or praise for the company in their quest for safety that involves their core shroud replacement program, I have to laugh and dismiss the source. In light of this I heavily discount anything Tsuneo Futami has to say. He is, IMO, a TEPCO stooge.

 

[NUCENG]

Thank you, the long discussed scaffold, aka "the green box", can be seen from this angle:

And some black smoke somewhere near the turbine buildings on the last pic.

diesel exhaust?

 

[timeasterday]

diesel exhaust?

Some debris or dirt on the lens. I'm a photographer and am used to seeing this.

 

[PietKuip]

What transpired on the Reagan was a few hours after the explosion of #3.

The article you point out tells the story. I'm unable to now find the blogs from sailors who said the entire ship was near panic, but read between the lines in this story and you can tell:

http://www.1310news.com/news/world/article/202681--uss-ronald-reagan-fought-contamination-amid-effort-to-aid-disaster-stricken-japan?ref=topic&name=index.php&title=

It would be interesting to know what nuclides were detected by the radiation people on the Reagan. A US citizen might try to obtain the data by a Freedom of Information request.

 

[dh87]

I am many pages behind in reading, but I am wondering whether I am correct that there has been only one publicized reading of radioactive materials in the Great Turbine Lakes in late March. The (corrected) numbers from #1 (low), #2 (very high, near 30 Sv/hr), and #3 (high, 750 mSv/hr) were reported by NISA. It seems to me that these are important numbers to monitor over time (except for the lethal doses of radiation received by the monitors) to determine whether more radioactive material is leaking from the reactors and where it's going. TEPCO might want to have these numbers to understand the scale of the problem.

 

[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