Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[SteveElbows]

I don't think so, it makes no sense, I suspect there could be language trouble. All three Tepco
press releases from March 13th from as early as 9am say that "spraying in order to lower pressure level
within the reactor containment vessel has been cancelled', here's the context:

"High Pressure Core Injection System has been automatically shut down and water injection
to the reactor is currently interrupted. We are examining alternative way to inject water.
Also, following the instruction by the government and with fully securing safety, steps to
lowering the pressure of reactor containment vessel has been taken. Spraying in order
to lower pressure level within the reactor containment vessel has been cancelled."

Ah but they don't actually say that it was canceled before it began. Its possible they canceled it once it was already in progress, because they were ready to use a different method.

Report to IAEA says spraying onto the PVC began at 07:39. At 08:41 they had opened AO valve, and at 09:08 operation to cause pressure reduction using SRV is mentioned, with a PCV pressure decrease trend noted at 09:20. By 09:25 they start injecting borated water via fire extinguishing line. (from table on page IV-81)

So I think its possible they sprayed the PCV for a short time, while they were waiting to get their valves in order.

The idea that this really happened is also mention on page IV-79 of the same document (http://www.kantei.go.jp/foreign/kan/topics/201106/pdf/chapter_iv-3.pdf)

Regarding the progress of events in the accident at Unit 3, previous analyses showed that the RCIC and HPCI ceased to function, so PCV spraying using fire engines and wet vent operation were carried out.

 

[SteveElbows]

While it was mostly lost at the time, Daini did report a fire and some scary moments after the tsunami and quake.

It wasnt completely lost, it got its own evacuation zone at the time, so I think some people tried to pay attention to it because of that. I certainly followed the early reports, but information was even more limited in early days and of course once it was brought to cold shutdown while Daiichi was busy exploding, the spotlight really shifted.

So I don't think it was off the radar at the time it was having problems, but it has been mostly off the radar ever since, so we never got much sensible discussion about it and very little interesting data.

 

[Bioengineer01]

http://search.japantimes.co.jp/cgi-bin/nn20110606x2.html

Of course the next thing you will hear after any mention of plutonium is that it is lower than the amount from bomb tests, and probably came from old bomb testing.

If only there was some way to find out.



Oh my. From reactor one. Science, it doesn't care about what you believe.

Fukushima 1 doesn't mean Unit 1, but plant number 1 or what we call Fukushima Daiichi

 

[Bioengineer01]

The pressure vessel of reactor 3 was is measuring 181 degrees Celsius at 5:00 am (JST).

Here is the link as reported by TBS News (Japanese): http://news.tbs.co.jp/newseye/tbs_newseye4745702.html

The link reports a NOT FOUND error by the remote server

 

[Bioengineer01]

Apparently they reduced the flow of water from 18 to 11.5 tons per hour in the hope of delaying the trenches from overflowing, as they are running out of options until the water treatment plant is up and running, but the temperature in the reactor appeared to rise as a result.

It also says that they are facing a difficult judgement as to how much cooling water to pump as they try to balance the risk of overheating the reactor vs overflowing the basements - "燃料を冷やすための注水量について難しい判断を迫られることになります".

The article does not say which way TEPCO are leaning, except to point out that to let the reactor get too hot would be a 'dangerous state of affairs'.

If you were TEPCO, what would you do?

Keep it cool and allow overflowing. I can't see how it is not overflowing already a huge rates. The intentional overflow is only a political hazard

 

[Bioengineer01]

What we need is not just a geologist (like me) but a geologist that reads Japanese and can find the data.

A quick scan through the Report of Japanese Government to the IAEA Ministerial Conference on Nuclear Safety June 2011 http://min.us/mvoVGLP appears silent on the matter of site geology. Maybe I missed it but a search on 'geology' got only one inconsequential result and there were no results on 'mudstone'.

Not for a final pass, but try using google translate as a first pass for searches. Then you can ask one of the Japanese/English Speakers here and in other forums to help

 

[robinson]

Fukushima 1 doesn't mean Unit 1, but plant number 1 or what we call Fukushima Daiichi

Probably. That doesn't answer the real question of course. Where in the plant did that plutonium come from? How did it get there?

Those would be important questions.

 

[StrangeBeauty]

Page IV-96 in the "Japanese Government report to the IAEA" shows an image that labels the large pipes that converge at the vent stack between Units 3 and 4, the "SGTS exhaust pipe junction".

http://www.kantei.go.jp/foreign/kan/topics/201106/iaea_houkokusho_e.html

Perhaps they are thinking that maybe the hydrogen flowed through the connecting pipe (about 200m of pipe all told) while the hydrogen was being produced and accumulating in Unit 3, and before Unit 3 exploded. Agree that it would be impossible for any hydrogen to travel through broken pipe after the explosion.

M&M thank you for the precise page number!

Im pretty convinced they are referring to the smaller pipes. Just look at exactly where they are highlighting the joining of the pipes from reactor 3 & 4, its well underneath the large pipe. Easy to miss because the join is the same shape as the larger pipe, and these other pipes are so small that its hard to see, but the yellow arrows are following the route of the smaller pipes round the outside of reactor 4 so I stick to this view.

Yes, if you zoom way in, it is clearly the smaller pipes below, and the yellow arrows indicate where they travel along the side of the outbuilding of #4. Looking the other way, it appears that going toward #3 they almost immediately go underground. In any case it's difficult to discern whether the pipes are intact or not, but shows that tepco's explanation isn't impossible (from the data we currently have at least). It still seems to me that the explanation of the hydrogen traveling between buildings is rather convoluted.

 

[StrangeBeauty]

It wasnt completely lost, it got its own evacuation zone at the time, so I think some people tried to pay attention to it because of that. I certainly followed the early reports, but information was even more limited in early days and of course once it was brought to cold shutdown while Daiichi was busy exploding, the spotlight really shifted.

So I don't think it was off the radar at the time it was having problems, but it has been mostly off the radar ever since, so we never got much sensible discussion about it and very little interesting data.

Most recent JAIF report on Daini:
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1307247746P.pdf

Of relevant interest within:

Latest Monitor Indication: 1.6μSv/h at 09:00, June 4th at NPS border
Evacuation Area: 3km from NPS(3/12 7:45), 10km from NPS(3/12 17:39), 8km from NPS(4/21)

Appears there is still an 8km evac area around the plant.
Interestingly, units 1,2 and 4 are at INES level 3, while #3 is not any level (no problems).

Side note: it appears they've dropped that format for a new one that only refers to Daiichi:
http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1307518788P.pdf

I too am wondering how the Pu got so far away from Daiichi. The town is approximately WSW from the plant which doesn't fit with wind direction for either the #1 (SE) or #3 (W) explosions (should be an E or ENE wind). Did the #3 explosion propel Pu 1.7 km against the wind?

 

[ascot317]

Which once again points out how unfortunate it is that we are lacking a poster knowledgeable of the subject of geology.

It simply can't be true that the underground rock formations, water tables and streams at the Fukushima site are an unknown.

Somebody did the engineering for that dam.

Cryptome.org posted some Japanese pdfs about the construction of Fukushima Daiichi.

It looks like there is information about the underground rock layers in it.

http://cryptome.org/0004/daiichi-build-01.pdf
http://cryptome.org/0004/daiichi-build-02.pdf

 

[MadderDoc]

They were spraying containment to condense any steam there and reduce containment pressure. With no power available they were probably using the fire fighting system to do this.

I see no data in support of that. No reduction of containment pressure was observed between the time PCV spraying is said to have been initiated (7:39 on March 13th ), and the time of the announcement that PCV spraying had been canceled (9:00 on March 13th).

 

[elektrownik]

In case of spraying water on reactor 3, but not on sfp look on this video which is from march 18: http://www.youtube.com/watch?v=v8Tds5d-ApU&feature=player_detailpage#t=71s

 

[Quim]

Where in the plant did that plutonium come from? How did it get there?

As I indicated in post #9238 the plutonium almost certainly came from the SFP of the #3 unit.

We can know it came from unit 3 because that was the only unit using MOX fuel (which has some plutonium in it.) It appears that the most likely way it "got there" was as a result of the explosion on March 14 which created the "mushroom cloud" that ejected material 300 to 500 meters high.

All evidence suggests that the vertical part of the #3 explosion originated in the SFP, not the containment structure, hence the source for the plutonium would be the SFP.

There my be a slim possibility that the plutonium came from reactors one or two as spent reactor fuel does contain traces of plutonium which is created as a byproduct of fission. But the explosion at unit 3 on March 14th offers a much more likely Scenario.

 

[etudiant]

As I indicated in post #9238 the plutonium almost certainly came from the SFP of the #3 unit.

We can know it came from unit 3 because that was the only unit using MOX fuel (which has some plutonium in it.) It appears that the most likely way it "got there" was as a result of the explosion on March 14 which created the "mushroom cloud" that ejected material 300 to 500 meters high.

All evidence suggests that the vertical part of the #3 explosion originated in the SFP, not the containment structure, hence the source for the plutonium would be the SFP.

There my be a slim possibility that the plutonium came from reactors one or two as spent reactor fuel does contain traces of plutonium which is created as a byproduct of fission. But the explosion at unit 3 on March 14th offers a much more likely Scenario.

With all respect, that theory seems to me intensely implausible.
The explosion in reactor 3 was a coarse detonation, leaving huge chunks of stuff flying through the air.
Had it tossed out bits of the fuel from the SPF, one would expect fuel rod assemblies among the debris, not microscopic traces so minute that it takes effort to distinguish them from bomb test fallout.
Imho, the scenario of vapor leaks from the molten fuel in reactor 1 fits the data much better.

 

[Bioengineer01]

Yes... a very telling pointer as to how they're still battling, and haven't had the time to really think ahead. It's been out of the main news for a good while but something will give.
So three reactors have melted through the 6inch thick steel pressure vessels. and corium is all over the place... if they've not had good scientists they've certainly had good PR people to get that news out so late and so inconspicuously!

 

[jim hardy]

search that 'govt report to iaea' for 'wet well vent' .

looks like there were several opportunities for small amounts of crumbly stuff from inside reactor to make it out via SRV's and containment vents..

infamous 'neutrons at the gate' were noticed about that time.

personally i think there was some rowdiness inside the vessels around times of seawater injection and venting.

 

[MiceAndMen]

Here are the number of pages of the Japanese language pdfs available at http://www.kantei.go.jp/jp/topics/2011/iaea_houkokusho.html :

001 pages 00-0-hyoushi.pdf
...
So I find a total of 714 pages (and 66.8 MB file size)

Ah, 381 pages of appendixes in the Japanese version of the report. Thanks tsutsuji-san. I will keep an eye out for the English version of the appendixes. They are not listed yet on the Prime Minister's website http://www.kantei.go.jp/foreign/kan/topics/201106/iaea_houkokusho_e.html

 

[elektrownik]

Wait, what ? Unit 5 is at atmospheric pressure, there was info that RPV was open to refueling but look what I found in report:

On the day of the earthquake, RPV pressure leakage tests had been conducted with fuel being loaded in the reactor.
But how much fuel ? all ?
...
In the reactor, the pressure had increased to 7.2 MPa because of the pressure leakage test; however, the equipment that had been applying pressure on the reactor pump halted because of the loss of power supply, leading to a temporary pressure drop. Then, the decay heat caused the pressure to moderately increase, resulting in a pressure of around 8 MPa. At 6:06 on March 12, pressure reduction was performed on the RPV, but the pressure continued to increase moderately because of the decay heat.
...
On March 13, water was successfully injected into the reactor using the condensate transfer pump at Unit 5, which received power from the emergency DG at Unit 6. Accordingly, after 5:00 on March 14, the reactor pressure and the water level were controlled by reducing pressure with the SRV and repeatedly refilling the reactor with water from the condensate storage tank through the condensate transfer pump in parallel.

Dont understand this, so there was no water in reactor after earthquake ?
How they reduced RPV pressure ?

 

[SteveElbows]

In case of spraying water on reactor 3, but not on sfp look on this video which is from march 18: http://www.youtube.com/watch?v=v8Tds5d-ApU&feature=player_detailpage#t=71s

The problem with trying to make the case that they were targeting something other than the fuel pool in that video, is that the very real possibility exists that they were trying to target the pool but were struggling. Certainly spraying into the pools did not seem to be done with ease until the long-armed concrete pumping equipment was used. And there are moments in that video where it seems clear we are witnessing them struggling to reach their target.

But I do concede that there could be other moments where they are deliberately targeting area other than fuel pool. And I think there is another video that was posted to this thread in the past that shows them spraying from yet another position and angle on another date, where the target of their spraying is rather unclear. We know that the sort of water injection they desperately wanted to achieve did not come until around march 24th if memory serves me correctly, so in theory they might have been trying even more desperate stuff in the interim, I find it hard to judge.

 

[robinson]

All spent fuel rods contain plutonium. The amounts in the stored fuel ponds should dwarf the small amount in the MOX fuel.

 

[Borek]

All spent fuel rods contain plutonium. The amounts in the stored fuel ponds should dwarf the small amount in the MOX fuel.

Yep. Compare Astronucs posts here and here.

 

[MiceAndMen]

search that 'govt report to iaea' for 'wet well vent' .

looks like there were several opportunities for small amounts of crumbly stuff from inside reactor to make it out via SRV's and containment vents..

infamous 'neutrons at the gate' were noticed about that time.

personally i think there was some rowdiness inside the vessels around times of seawater injection and venting.

Let's also not forget the NRC report from 26 March http://cryptome.org/0003/daiichi-assess.pdf which said

... fuel may have been ejected from the pool (based on information from TEPCO of neutron sources found up to 1 mile from the units ...

I would have expected the Japanese Govt report to the IAEA to have mentioned that finding, but there is nothing in there about it. I'm wondering now if the information someone at TEPCO conveyed to the NRC team was erroneous, or the report neglected to mention it, or maybe it's in there but I just missed it.

 

[Bioengineer01]

Well, I happen to be a geologist, specialized in soil and groundwater contamination. I am sure that the geology and geohydrology of the site are known, in order to be able to design the foundations of the plant and in order to design the groundwater withdrawal system, necessary to keep the basements of the plant dry (I understood that such a system exists).

I have added a simple sketch of what seems to me the most likely situation of the Fukushima plant. I assume the following, based on what I see at Google Earth:
- the plant has been built on a platform, partly excavated into the slope and partly situated on a layer of rubble, bulldozed into the sea.
- the general direction of ground water flow is perpendicular towards the sea;
- at the foot of the slope there is probably some kind of drainage ditch which collects both surface runoff and ground water coming from higher grounds;
- the whole platform is probably paved with concrete of asphalt and provided with a rainwater drainage system;
- the rain water and ground water collected in the drainage ditch and the drainage system is led into the sea.

Based on the above:
- contaminated surface runoff will probably be directly discharged into the sea unless this water is intercepted and collected somewhere (which is not the case afaik);
- contaminated surface runoff may leak into the ground in case of damaged pavements and/or drainage pipes;
- contaminated water in the reactor buildings may leak into the ground in case of damaged walls/floors/underground pipes, etc.

The time it takes for the contaminated ground water to reach the sea depends on the permeability of the ground (which may consist of bedrock, rubble and possible also weathered bedrock (soil)), on the slope of the groundwater table towards the sea and on the chemical behavior of the radioactive substances.

Hope this helps.

Thanks a LOT! I am no expert but own a house in a similar location and had to become familiar with groundwater flows and contamination. I couldn't imagine any possible way that there were not active paths from the basements to the Ocean after the earthquake activity they had...

 

[MiceAndMen]

Cryptome.org posted some Japanese pdfs about the construction of Fukushima Daiichi.

It looks like there is information about the underground rock layers in it.

http://cryptome.org/0004/daiichi-build-01.pdf
http://cryptome.org/0004/daiichi-build-02.pdf

First found by rowmag here early this morning

Not sure if this is what you are looking for, but you can download a paper on TEPCO's civil engineering for the site, which was submitted to a civil engineering journal in 1967, from here:
http://www.doboku-g.com/DownloadPDF.aspx?TocID=6608

You will have to provide a mail address twice (and not an obviously free mail address), and check a box agreeing to let the journal send you notices now and then, click on the button in the lower right, and then you will be mailed a URL from which to download the PDF file.

He posted a similar link for the second one a short time later. Those documents are obscure enough to make it highly unlikely that cryptome and rowmag found them within a few hours of each other out of sheer coincidence. Just sayin'.

Edit: Cryptome's source for the docs confirmed on next page. Good job, zapperzero.

 

[Quim]

The explosion in reactor 3 was a coarse detonation,

What do you mean by that?

leaving huge chunks of stuff flying through the air.

There were large chunks, medium sized chunks, small pieces and microscopic pieces (for example: very fine particles made the "cloud" dark brown.)

Had it tossed out bits of the fuel from the SPF, one would expect fuel rod assemblies among the debris, not microscopic traces so minute that it takes effort to distinguish them from bomb test fallout.

A fuel rod assembly would never have made it out of the pool in one piece, or even in large pieces - and had individual pellets made it out in one piece we wouldn't expect them to have drifted 1.7 kilometers away. The bigger pieces of the #3 explosion would have landed close to #3.

Plutonium in fuel rods is not in pellet sized chunks anyway. It would be blended in with the U to make the pellets (Pu only accounts for 6% of the active material in a rod.) So it would only exist in trace quantities at anyone spot even in a brand new rod.

Also we have no idea how much material was ejected from the #3 SFP. When we learn more about the energy source that produced that vertical detonation we may also find that most of the material from the fuel rods are still in the pool.

Imho, the scenario of vapor leaks from the molten fuel in reactor 1 fits the data much better.

How would you account for Pu traveling 2 km from the rest of the corium?
Pu is not soluble, it is not as easily dispersed as cesium and Iodine.

 

[etudiant]

What do you mean by that?


There were large chunks, medium sized chunks, small pieces and microscopic pieces (for example: very fine particles made the "cloud" dark brown.)


A fuel rod assembly would never have made it out of the pool in one piece, or even in large pieces - and had individual pellets made it out in one piece we wouldn't expect them to have drifted 1.7 kilometers away. The bigger pieces of the #3 explosion would have landed close to #3.

Plutonium in fuel rods is not in pellet sized chunks anyway. It would be blended in with the U to make the pellets (Pu only accounts for 6% of the active material in a rod.) So it would only exist in trace quantities at anyone spot even in a brand new rod.

Also we have no idea how much material was ejected from the #3 SFP. When we learn more about the energy source that produced that vertical detonation we may also find that most of the material from the fuel rods are still in the pool.



How would you account for Pu traveling 2 km from the rest of the corium?
Pu is not soluble, it is not as easily dispersed as cesium and Iodine.

Exactly, you put your finger on the key issue.
Afaik, minuscule flecks of plutonium have been discovered up to 2km from the plant, not bigger pieces or fuel debris. That suggests to me emissions of vaporized fuel, probably through some circuitous route, because the amounts are so small. It may indicate much higher than expected contamination inside parts of the reactor building as well. But it is inconsistent with an explosion, because there would be a spectrum of debris, which does not seem to be the case here.

 

[NUCENG]

Let's also not forget the NRC report from 26 March http://cryptome.org/0003/daiichi-assess.pdf which said
I would have expected the Japanese Govt report to the IAEA to have mentioned that finding, but there is nothing in there about it. I'm wondering now if the information someone at TEPCO conveyed to the NRC team was erroneous, or the report neglected to mention it, or maybe it's in there but I just missed it.

Just for clarification. Safety Relief Valves (SRVs) vent from the reactor pressure vessel (RPV) to quenchers below the water line in the torus. This below water discharge helps scrub particulates and ions before it gets into the suppression chamber air space. Operation of the wetwell vent releases steam and non-condensible gasesw and small amounts of aerosols through the stack elevated release point. Release of heavy metals or chunks of fuel via this path is less than credible.

The only confirmed reports of Plutonium found so far have been at extremely low levels that could be leftover from the Fat Man bomb dropped on Nagasaki or from other atmospheric testing of plutonium weapons. The initial NRC speculation of fuel being bulldozed under kilometers from the site have not been confirmed to my knowledge. As reliable as early reports were, this could have easily been due to hotspots contaminatred by cesium or other fission products in fallout. If there is more information about that early report, please post that data.

 

[MiceAndMen]

Completely agree, the question I have is, whether anybody in the forum knows if it is true that this is something that TEPCO could be measuring to understand if the Corium is in the ground. And I know that we can't know if they are doing it or not, I am just curious if you think that this is something that could be done if they wanted to: "There are sensitive sensors all around the grounds listening for underground activity, as well as satellite based imagery used to locate bunkers and tunnels that can image the ground density. 1300C material generates pressure underground that alters the density of the ground, and these changes can be detected and visualized"

There are several papers on the web that describe how the ablation of concrete by corium depends heavily on the type of concrete. For limestone concrete the ablation is isotropic, while for silica concrete the ablation is anisotropic.

http://journals1.scholarsportal.info/details.xqy?uri=/03064549/unassigned/nfp_tioocwctvvts.xml

There are other papers you can find using google. Some are recent, some not so recent. A quick glance at them suggests that it would definitely be possible to detect if concrete ablation was occurring assuming, of course, you had working sensors nearby. Another reason to start preparations for probing inside the PCVs.

 

[razzz]

What did you expect?

From Asahi Shinbun (12:00AM JST 6/9/2011):
...最も多かったのは浪江町赤宇木で、それぞれ２５０ベクレルと１５００ベクレル。北西部に３６キロ離れた飯舘村では１２０ベクレルと１１００ベクレルで、 これまでに２０キロ圏内で検出されていた値よりも高かった。ほかに田村市、広野町、川内村、南相馬市、二本松市でもストロンチウムが検出された。文科省は 採取した土壌をさらに細かく分析するという。

The highest numbers come from the Akogi district in Namie-machi, with 250 becquerels/kg strontium-90 and 1,500 becquerels/kg strontium-89. In Iitate-mura, 36 kilometers northwest of the plant, 120 becquerels/kg strontium-90 and 1,100 becquerels/kg strontium-89 were detected; these amounts were even higher than those that had been detected earlier within 20 kilometer radius from the plant. Radioactive strontium was also detected from the soil samples from Tamura City, Hirono-machi, Kawauchi-mura, Minami-Soma City, Nihonmatsu City. The Ministry of Education and Science will further analyze the soil samples.

　放射性ストロンチウムはセシウムに比べ、炉心がより高温になってから溶け出し、気化する。それが検出されたことは、炉心が早い段階で溶け出し、その後に放射能の放出につながったことを意味するとみられる。

Radioactive strontium melts at a higher temperature than cesium to be volatilized. The fact that strontium has been detected would mean that the reactor core started to melt from the early stage of the accident, and then radioactive materials were released...

@ http://ex-skf.blogspot.com/2011/06/now-they-tell-us-series-strontium-was.html" he comments:

Non-government, non-experts like the rest of the Japanese already suspected it from long ago, particularly when they knew that strontium, plutonium, uranium, even americium, of Fukushima origin had been detected in the US.

 

[Quim]

Afaik, minuscule flecks of plutonium have been discovered up to 2km from the plant, not bigger pieces or fuel debris. That suggests to me emissions of vaporized fuel, probably through some circuitous route, because the amounts are so small.

This idea you seem to have that there has to be large pieces of the explosion 2 km away or nothing at all makes no sense to me.

Where did you come by the model of particle disbursement that you hold?

it is inconsistent with an explosion, because there would be a spectrum of debris, which does not seem to be the case here.

There is no evidence for or against "a spectrum of debris" anywhere that I know of.