How #Fukushima's Spent Fuel Pool Cooling Works

(or is supposed to work, considering numerous leaks...)

Spent Fuel Pools of Fukushima I Nuclear Power Plant, particularly that of Reactor 4, continue to be in the news inside and outside Japan.

Dr. Hiroaki Koide of Kyoto University spoke in New York on May 3 and held a press conference on the status of Fukushima I Nuclear Power Plant and radiation contamination in Japan as he sees it.

He said about the Reactor 4 Spent Fuel Pool (I'm reading off from the Japanese transcript),

補強工事というものを施した、ということになっています。

So-called reinforcement work was done [on Reactor 4 SFP]. (My translation, not the translation at the press conference)

Then, one of my blog readers sent me a link to the post that has an audio clip of a radio program, in which nuclear expert Arnie Gundersen seems to be saying that TEPCO has been pumping water into the Reactor 4 Spent Fuel Pool from the top, the water drains to the basement, and TEPCO is pumping the water from the basement back into the SFP.

That's news to me, but then I haven't carefully checked how the cooling of the Spent Fuel Pools at Fukushima I Nuclear Power Plant has been done after TEPCO installed the temporary heat exchangers. So I decided to look for info, and here's what I've found.

Asahi Shinbun had an article on the temporary cooling systems for the SFPs back in June last year, and here's their simplified diagram of the system (missing the Skimmer Surge Tank):

Here's what TEPCO released on July 9, 2011 after they tested the pipes after installing the heat exchanger and the air cooling system (secondary cooling) for Reactor 4 SFP:

Here's TEPCO's diagram of the same system, released on April 16 this year after the Reactor 4 SFP cooling system stopped due to a leak (the information was released only in Japanese; I labeled "Heat Exchanger"):

As far as I can tell, it is basically a closed system though leaks have happened. The excess water from the Spent Fuel Pool goes to the Skimmer Surge Tank, which then is then goes through the heat exchanger to remove heat (0.9MW in the Reactor 4 SFP, as per TEPCO's press release above). The water is then pumped back into the SFP.

Back in February when the water level of the Reactor 4's Skimmer Surge Tank was dropping more than usual, TEPCO injected the water from the bottom of the Reactor Pressure Vessel (which is filled with water). That water went from the RPV to the Reactor Well to the SFP to the Skimmer Surge Tank.

Contaminated water in the turbine building basements in Reactors 1, 2, 3 and 4 gets treated through cesium absorption towers (Kurion or SARRY) and desalination systems, then pumped back into the Pressure Vessels but not to any of the Spent Fuel Pools.

But all my information is from publicly available sources (newspapers, TEPCO, etc.). Mr. Gundersen may have his own private sources of information that points to the collapsing Reactor 4 SFP or the SFP water boiling. (As far as I can gather, the temperature of the SFPs at Fukushima is below 30 degrees Celsius.)

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Fairewinds' Gundersen: "Reactor 3's Spent Fuel Pool Worse Off"

ENENEWS has the link to the podcast, for those who are interested.

ENENEWS post: http://enenews.com/gundersen-3-fuel-pool-worse-4-mechanically-rubble-pool-rubble-gotten-audio

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Fairewinds' Gundersen Scrapes Soil in Tokyo, Says It's Like Picking Flowers in "Radioactive Waste"

Enenews (3/25/2012) has a post featuring the recent video by A. Gundersen of Fairewinds Associates telling the viewers how he collected soil samples in Tokyo on his recent trip there and found them to be "radioactive wastes" by the US standard.

There is a screen capture from the video at Enenews, showing the result of the soil analysis.

For the Sample NO.1 (Shibuya-ku), the table shows:

cesium-134: 137 pCi/g or 5.069 Bq/g, (or 5069 Bq/kg)
cesium-137: 167 pCi/g or 6.179 Bq/g, (or 6179 Bq/kg)
(cesium total: 11,248 Bq/kg)
cobalt-60: 40 pCi/g or 1.48 Bq/g, (or 1480 Bq/kg)

1 picocurie (pCi) is 0.037 becquerel (Bq).

Now these numbers are way out of line from anything I've seen in the radioactivity measurements of the soil done in Tokyo metropolitan areas for radioactive cesium (no info about cobalt-60, as the nuclide has never been measured by the authorities), unless you measure the rooftop sediments or the dirt near the gutters or the side of the road. So I watched the video.

Mr. Gundersen says when he saw some dirt he just took it, but looking at where he collected the samples they are all locations that tend to accumulate and concentrate radioactive materials - at the root of a big tree, dirt in between the pavements, moss or dirt on the side of the road, etc. In the video he is seen scooping the dirt with a plastic spoon, so I assume it was either loose soil on the very top surface, probably no more than 1 or 2 centimeters or sediments or moss in the crack or on the surface of the pavements.

That makes sense, as these locations tend to concentrate radioactive materials, as we know know after one year.

So, what are the measurements done in Tokyo metropolitan areas in a more standardized way?

Journalist Kouta Kinoshita and his group of volunteers have done an extensive, systematic soil tests in Tokyo metropolitan areas. Let's see what their test results say. They didn't test cobalt-60, so I can only compare cesium-134 and cesium-137.

From Kinoshita's group's test results of the soil samples taken in Tokyo metropolitan areas, three of the locations that might be similar to Gundersen's; their samples were taken from the surface to 5 centimeters deep (standard practice), and none was taken from the rooftops or in between the pavements:

Shibuya-ku:

cesium-134: 136 Bq/kg
cesium-137: 182 Bq/kg

Chiyoda-ku:

cesium-134: 323 Bq/kg
cesium-137: 416 Bq/kg

Zushi (near Kamakura, Kanagawa):

cesium-134: 0
cesium-137: 0

The detection limit is 1 Bq/kg. Pre-Fukushima Shinjuku-ku in Tokyo had 1.5 Bq/kg of cesium-137 in soil (in 2009).

Mr. Gundersen says in his video,

How would you like it if you went to pick your flowers and were kneeling in radioactive waste? That is what is happening in Tokyo now.

That's a rather threatening imagery, although I don't think you go pick your flowers in between the pavements or in the roadside sediments.

The clearance level of radioactive waste in Japan is 1 Bq/gram, or 1000 Bq/kg. Below that level, radioactive waste is not considered radioactive, and can be disposed of as industrial waste.

You may ask "Why is the Ministry of the Environment saying it's OK to bury anything with 8000 Bq/kg of radioactive cesium?" The answer is easy: the clearance level only applies to rad waste inside a nuclear facility (nuclear plant, medical or industrial facility that uses radioactive materials). Once radioactive materials escape into the environment, there was no law or regulation that stipulates how they should be treated. So the Japanese government hastily crafted and passed a law allowing the burying of anything with 8000 Bq/kg of radioactive cesium and below.

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Arnie Gundersen's Latest Video Link

For those of you in Japan and don't read the language and wondering how to get to Fairewinds Associates' English site at all, you can follow this link and see their latest video on Youtube.

http://youtu.be/M-gFV_K-Qtk

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Arnie Gundersen: Lethal Levels of Radiation at Fukushima: What Are the Implications?

In the latest video on Fukushima (8/4/2011), Arnie Gundersen of Fairewinds Associates thinks 10-plus sieverts/hour radiation at the base of the exhaust duct is from cesium that has been released from the Containment Vessel of Reactor 1, condensed and accumulated at the bottom over time.

I don't necessarily agree with his hypothesis, but that's not what I was surprised when I saw the video. He says that the highly radioactive debris have been "bulldozed under", and when the debris are unearthed in the future we will see more high radiation spots.

I don't remember reading the news that the radioactive debris at the plant were ever actually buried. I remember one person who did say "Dig a hole, bury the debris so that the workers can work", Michio Ishikawa of the Japan Nuclear Technology Institute, a strong proponent of nuclear power who expressed a very pessimistic view of the TEPCO/government response to the Fukushima nuclear accident in late April.

Ishikawa also said the core had melted down and probably out of the RPV. That was officially admitted 2 weeks later. He also said a bridgehead must be built do the reactor, and forget about the turbine building. That also happened. Workers entered the reactor buildings, and they installed the heat exchangers for the Spent Fuel Pools (Reactors 2, 3, 4, and Reactor 1's heat exchanger has just been installed).

Is it possible that Ishikawa's suggestion on radioactive debris was also carried out? Or Is Gundersen simply mistaken? Or does he have some insider source?

Anyway, here's Mr. Gundersen's video:

Lethal Levels of Radiation at Fukushima: What Are the Implications? from Fairewinds Associates on Vimeo.

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Arnie Gundersen: Japanese Should Limit the Radiation, Not the Information

Arnie Gundersen's latest video on Fukushima.

Ex Japanese Nuclear Regulator Blames Radioactive Animal Feed on "Black Rain" from Fairewinds Associates on Vimeo.

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Arnie Gundersen: Hot Particles From Japan to Seattle Virtually Undetectable When Inhaled or Swallowed

Arnie Gundersen's latest video talks about "hot particles". He mentions a metallic taste experienced by some people in Japan and on the west coast and says it is a sign of radiation exposure.

Hot Particles From Japan to Seattle Virtually Undetectable when Inhaled or Swallowed from Fairewinds Associates on Vimeo.

To defend TEPCO somewhat, though, it was not TEPCO who doubled the estimate of the radioactive materials released from Fukushima I Nuclear Power Plant; it was the government agency, the Nuclear and Industrial Safety Agency.

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Arnie Gundersen: "On-and-Off Recriticality Possible in Reactor 3"

I was listening the podcast of the interview Arnie Gundersen gave to Chris Martenson the other day (in order to translate into Japanese) and noticed something I had missed when I skimmed through the transcript for my post.

Gundersen is saying that 10% of the fuel core of the Reactor 3 may be repeating a re-criticality, on and off:

"Unit 3 may not have melted through and that means that some of the fuel certainly is lying on the bottom, but it may not have melted through and some of the fuel may still look like fuel, although it is certainly brittle. And it's possible that when the fuel is in that configuration that you can get a re-criticality. It's also possible in any of the fuel pools, one, two, three, and four pools, that you could get a criticality, as well. So there’s been frequent enough high iodine indications to lead me to believe that either one of the four fuel pools or the Unit 3 reactor is in fact, every once in a while starting itself up and then it gets to a point where it gets so hot that it shuts itself down and it kind of cycles. It kind of breathes, if you will.

"I think it's a relatively significant amount – maybe a tenth of the nuclear reactor core starts back up and shuts back down and starts back up and shuts back down. And that’s an extra heat load; you are not prepared to get rid of one tenth of a nuclear reactor’s heat by pumping water in the top."

Hiroaki Koide of Kyoto University suspected an on-and-off recriticality in the Reactor 1 back in early April when TEPCO announced, supposedly erroneously, chlorine-38 was detected. Dr. Tetsuo Matsui of Tokyo University suspected recriticality in the Reactor 2 and/or the Reactor 4 Spent Fuel Pool. Gundersen suspects an on-and-off recriticality in the Reactor 3 (or any of the Spent Fuel Pools).

Below is the chart of iodine-131 detection at the Federal Office of Radiation Protection in Germany, plotting the CTBTO station data from around the world. Station 38 is Takasaki, Gunma Prefecture in Japan, 218 kilometers (135 miles) from Fukushima I Nuclear Power Plant. I always thought it was rather peculiar that there seemed to be periodic spikes in the amount of iodine-131 (also of cesium-137 but to a lesser degree) followed by a relatively calm, steady decline.

Could these spikes indicate what Gundersen is talking about? On-and-off recriticality?

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#Fukushima I Nuke Accident: Arnie Gundersen's Interview with Chris Martenson

(h/t Helios)

"Exclusive Arnie Gundersen Interview: The Dangers of Fukushima Are Worse and Longer-lived Than We Think"

Part 1

Part 2

Gundersen thinks the melted fuel is at the bottom of Containment Vessels in Reactor 1 and 2; for Reactor 3, he thinks there may be some left in the Reactor Pressure Vessel, causing a local, on-and-off criticality:

Arnie Gundersen: Yes, once the uranium melts into a blob at these low enrichments, four and five percent, it can’t make a new criticality. If criticality is occurring on the site - and there might be, because there is still iodine 131, which is a good indication - it is not coming from the Unit 1 core and it's not coming from the Unit 2 core, because those are both blobs at the bottom of the containment.

Chris Martenson: All right, so we have these blobs, they’ve somehow escaped the primary reactor pressure vessel, which is that big steel thing and now they are on the relatively flat floor of the containment – they concrete piece – and you say Unit 2 is roughly the same story as Unit 1 – where’s Unit 3 in this story?

Arnie Gundersen: Unit 3 may not have melted through and that means that some of the fuel certainly is lying on the bottom, but it may not have melted through and some of the fuel may still look like fuel, although it is certainly brittle. And it's possible that when the fuel is in that configuration that you can get a re-criticality. It's also possible in any of the fuel pools, one, two, three, and four pools, that you could get a criticality, as well. So there’s been frequent enough high iodine indications to lead me to believe that either one of the four fuel pools or the Unit 3 reactor is in fact, every once in a while starting itself up and then it gets to a point where it gets so hot that it shuts itself down and it kind of cycles. It kind of breathes, if you will.

The Fukushima accident is worse than Chernobil, Gundersen says:

Arnie Gundersen: Well, this event is – I have said it's worse than Chernobyl and I’ll stand by that. There was an enormous amount of radiation given out in the first two to three weeks of the event. And add the wind and blowing in-land. This could be – it could very well have brought the nation of Japan to its knees, I mean there is so much contamination that luckily wound up in the Pacific Ocean as compared to across the nation of Japan. It could have cut Japan in half. But now the winds have turned, so they are heading to the south toward Tokyo and now my concern and my advice to friends that if there is a severe aftershock and the Unit 4 building collapses, leave. We are well beyond where any science has ever gone at that point and nuclear fuel lying on the ground and getting hot is not a condition that anyone has ever analyzed.

So the plants, you will see them steaming and as summer goes on, you will see them steaming less, because the air is warmer, but it's not because they are not steaming, you just don’t see it. Because this event occurred in March and it was cool there, so you will see the steam a lot easier. Those plants are still omitting a lot of radiation. Nowhere near as much as on the first two weeks, but a lot of radiation: cesium, strontium, and mainly cesium and strontium – those are going to head south, whether or not there is a tropical hurricane. The wind is going to push it south this time and so the issue is not the total radiation you might measure with a Geiger counter in your hand, but hot particles.

And TEPCO and the Japanese government can't just give up and pour concrete over the mess, because the cores are just too hot:

Chris Martenson: So talk about -- realistically – I mean this is going to be months, years, whatever, it's going to take a long time. What do they do at this point, are they going to entomb these things, are they required to just keep dumping water on these things until they finally cool down, capturing water all the way through? Or is there some way that they can maybe just throw up their hands and just pour a bunch of concrete on it and call it a day?

Arnie Gundersen: I think eventually they may get to the point of throwing up their hands and pouring the concrete on. They can’t do that yet, because the cores are still too hot. So we are going to see the dance we’re in for another year or so, until the cores cool down. At that point, there’s not anywhere near as much decay heat and you probably could consider filling them with concrete and just letting sit there, like we have it at Chernobyl, as a giant mausoleum. That would work for units 1, 2, and 3. Unit 4 is still a problem, because again all the fuel is at the top and you can’t put the concrete at the top because you will collapse the building and it's so radioactive, you can’t lift the nuclear fuel out. I used to do this as a living and Unit 4 has me stumped.

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How GE's Mark 1 Reactor Caused #Fukushima I Nuke Plant Accident

(UPDATE) The presentation was created by the Union of Concerned Scientists, and was posted later at Fairewinds Associates. (h/t anon reader)

---------------------------------------

I found this presentation at Arnie Gundersen's Fairewinds Associates website. I do not know who created the presentation, as there is no credit on the slides. I'm assuming it was Fairewinds Associates. The presentation was posted on their site on April 25.

It shows GE's now notorious Mark 1 BWR nuclear reactor with actual photos and diagrams of the reactor, and explains how the accident progressed, given such design.

Fukushima-Tragedy

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#Fukushima I Nuke Plant: Ground May Have Shifted So Much That It May Have Caused Damage to Foundation (Guest Post)

Arnie Gundersen of Fairewinds Associates mentioned in the latest video, in passing, toward the end, that Fukushima I Nuke Plant has sunk about a foot (about 30 centimeters) and that the foundation of the buildings must have been damaged.

One of the readers of my Japanese blog that has the Japanese translation of the video got curious and did some research using the data from the government agency (the Geospatial Information Authority of Japan), and came to a conclusion that the area where the plant sits may indeed have moved quite a bit, not just vertically but also horizontally.

His conclusion:

Vertical: - 50 centimeters (it sank 50 centimeters)
Horizontal: 220 to 250 centimeters to the east.

The following is the findings of Dr. Shunichi Ono, a medical doctor in Kumamoto Prefecture in Kyushu, from his blog (original in Japanese; my translation). [My notes in square brackets]

(Dr. Ono's post begins)------------------------------------

[After mentioning Arnie Gundersen's comment about Fukushima I having sunk a foot]

If it is true, it's a big story. Large-scale land subsidence have already been reported in Iwate and Miyagi.

So I searched the Geospatial Information Authority of Japan (GSI) site, and found the following information (in Japanese). [It is a list of cities and towns in Iwate, Miyagi, and Fukushima and the size of the land subsidence in each.]

http://www.gsi.go.jp/common/000060316.pdf

Overall, the land subsidence is between 20 to 80 centimeters.

The southern-most city on this list is Minami-Soma City in Fukushima Prefecture, located 20 kilometers north of the Fukushima I Plant. The land subsidence is 30 centimeters.

What about further south?

So I contacted the GSI and asked. Their answer was:

• The results of measurement south of Minami-Soma City will be compiled by the end of this year;

• There are electronic points of reference, and these results have already been made public.

http://www.gsi.go.jp/chibankansi/chikakukansi40005.html

Horizontal movement:



Vertical movement:

Map that plots the levels of movement [当変動量線図I do not know the official terminology], horizontal, Fukushima Prefecture

Map that plots the levels of movement, vertical, Fukushima Prefecture

Fukushima I Nuclear Power plant is located about halfway along the Fukushima coastline. Checking the maps above, the ground underneath the plant may have moved:

Horizontal: 2 meters and 20 centimeters to the east;
Vertical: -40 centimeters (it sank)

(Update) Here's the map of Fukushima Prefecture.

Fukushima I Nuclear Power Plant is Located in Futaba-machi and Okuma-machi [red circle].

Fukushima II Nuclear Power Plant is located in Tomioka-machi and Naraha-machi [blue circle].

Again, looking at the maps above that shows the levels of movement,

Land subsidence at both plants: more than 50 centimeters;
Horizontal movement: between 220 to 250 centimeters (possibly distorting the ground).

These maps were created by the GSI; they are accurate, with the measurement error of 10 centimeters [for non-electronic points of reference].
　
If the ground shifted this much, I wonder if the foundation of the Fukushima Nuclear Power Plant has indeed sustained some grave damage.

The current seismic safety evaluation only uses ground motion acceleration (Gal, in cm/s^2):

mass * acceleration = force

and the evaluation is whether the structure can withstand this force.

This earthquake clearly brought about the distortion of the ground. Seismic safety evaluation should include the effect of land subsidence and horizontal movement. Needless to say, land subsidence and horizontal movement don't occur uniformly within the same plant compound.

Is it even possible to build a structure that wouldn't be affected by an earthquake that distorts the ground?

I suspect it is a given that the ground would not shift.

I think this is a serious problem.

(end of the post)----------------------------

Dr. Ono's bio says he once worked for TEPCO, before he quit and enrolled in a medical school. In his latest post (in Japanese), he diagnoses Japan's PM Kan and Nuclear Safety Commission chief Madarame as suffering dementia, based on their remarks about the state of the Fukushima I reactors.

The Geospatial Information Authority of Japan has an interactive map that shows the ground movements (vertical and horizontal). It's in Japanese only. Click on a red dot (point of reference), and you can see how much movement that point has experienced.

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Arnie Gundersen: 1 Step Forward, 4 Steps Backward at #Fukushima

Arnie Gundersen of Fairewinds Associates says:

• Reactor 1's fuel melted and probably dropped to the Containment Vessel;

• Reactor 2 is leaking like a sieve;

• Reactor 3 may have another hydrogen explosion;

• The plant has sunk about a foot, and the concrete foundation may have cracked.

So what was the "step forward"? That TEPCO was able to enter the Reactor 1 reactor building to install equipments to measure the true water levels.

He also refers to the ramification on the US nuclear regulations now that it has been proven possible for a Containment Vessel to get damaged. The Containment Vessels for the Reactors 1, 2 and 3 at Fukushima are all officially acknowledged to have been damaged.

Toward the end, he mentions a high school in the contaminated area 50-60 kilometers from the plant. He says it is unconscionable to keep the school open.

Fukushima - One Step Forward and Four Steps Back as Each Unit Challenged by New Problems from Fairewinds Associates on Vimeo

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