Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[zapperzero]

Anyone got any ideas?

Oh I got lots of ideas. No data, though. TEPCO said at some point quite late on that they would start monitoring the steam. They haven't got around to publishing any results.

 

[Caniche]

Occam's razor and the circumstantial evidence strongly suggest that recriticality has occurred somewhere at Fukushima Daiitchi.

I have lost track of the number of posts I've made on this 'theory'.I would also like to know what has and is going up the vent stack?

Are we talking about aerosolized actinides including polonium?

Are the releases ongoing - and at what levels?

Why isn't a helicopter collecting samples from the vents now?

Who knows ,the chimney is pretty irrelevant since the RPV got melted the fuel went walkies,any connection to the turbines was probably frazzled and containment of any kind was blown to smithereens .
As for ongoing releases ,nobody is talking . Iaea updates have petered out, RADNET and RIMNET went silent months ago ,TEPCO ,well there is no meltdown oh hang about. In short,the track record of official bodies when providing information leaves much to be desired in terms of accuracy and promptness.I'm guessing their taciturn approach is not a good sign.
But you already knew that

 

[robinson]

I would also like to know what has and is going up the vent stack?

I think any concerned party would want to know that. I want to know why it is impossible to simply find out. Or if they know, why is it top secret information?

 

[joewein]

I would also like to know what has and is going up the vent stack?
(...)
Why isn't a helicopter collecting samples from the vents now?

The blowers of the standby gas treatment system haven't worked since the blackout, so they aren't going to push anything up the stacks.

Somebody more knowledgeable please correct me if I'm wrong, but the stacks should not be a likely suspect for emissions at this stage. They would have been while the RPV and containment were under high pressure from steam and hydrogen and emergency venting took place from the wet well (S/C). Since then the pressure gradually dropped and some (or all) of the primary containments are suspected of no longer being able to hold pressure. The assumption is that gas can now leak either way, which is why nitrogen is being injected to try to ensure that the containment atmosphere remains inert.

TEPCO was monitoring radiation levels near the perimeter of the plant over several months after when they started nitrogen injections at the plant, to see if N2 flushes radioactive gases from the containment into the environment but apparently didn't detected anything ineresting:
http://www.tepco.co.jp/en/nu/fukushima-np/f1/index8-e.html

A lot of the radioactivity should now be contained inside the wet wells, either from venting or from being washed there via the downcomer tubes from the dry well, if cooling water leaks out of the bottom of the RPV or steam from the RPV condenses inside the dry well.

The decay heat should keep the S/C pretty warm. The 4000 mSv/h spot inside unit 1 was near steam from the S/C and there's a lot of gamma radiation coming up through the concrete floor of the first floor (1F) of the reactor buildings, which they're shielding with heavy steel plates to protect crews performing work inside (new instruments, etc).

 

[zapperzero]

http://www.power-eng.com/news/2011/09/1499357613/team-finds-possible-cause-of-fukushima-no-4-reactor-blast.html

Radiogenic hydrogen as a cause for explosion in #4 reactor - theory is being put forward by

team of researchers from the University of Tokyo, the Japan Atomic Energy Agency and others

. Apparently they did some small-scale experiment.

 

[LabratSR]

Recently released Tepco video showing the water injection system with English dubs.

http://www.youtube.com/user/AtomicPowerReview

 

[NUCENG]

http://www.power-eng.com/news/2011/09/1499357613/team-finds-possible-cause-of-fukushima-no-4-reactor-blast.html

Radiogenic hydrogen as a cause for explosion in #4 reactor - theory is being put forward by . Apparently they did some small-scale experiment.

Aw shucks, we were there back in May on PF!

AntonL found a DOE report and suggested this back on May 7:

https://www.physicsforums.com/showpost.php?p=3287847&postcount=6068

I did some additional calcs and concluded it was a possibility and would explain initial inspection results that fuel in SFP4 was not significantly damaged:

https://www.physicsforums.com/showpost.php?p=3329698&postcount=8496

Now there is an experiment that supports the phenomenon. Still isn't enough for proof, but it is good to know.

Recently they also determined that the Unit 4 side of the SBGT and hardened vent ducting showed relatively low contamination levels. This would also be consistent with detonation of radiolytic hydrogen without releasing a lot of the fission products from the pool.

 

[Caniche]

Recently released Tepco video showing the water injection system with English dubs.

http://www.youtube.com/user/AtomicPowerReview

"the boric acid solution will be injected immediately in the event of a re-criticality"verbatim hmmm that's one debate signed and sealed then, maybe

 

[zapperzero]

Now there is an experiment that supports the phenomenon. Still isn't enough for proof, but it is good to know.

More experiments
http://web.engr.oregonstate.edu/~petersr/RadiolyticEnhancementLiterature/Water%20Decomposition%20Paper%204%20Kalinichenko.pdf

 

[tsutsuji]

Unit 2:

At 2:59 pm on September 14, we started injecting water to the reactor
through core spray system water injection piping arrangement in addition
to the water injection through the reactor feed water system piping
arrangement.
Water is currently injected at approx. 4 m3/h through reactor feed water
system piping arrangement, and at approx. 1 m3/h through core spray
system water injection piping arrangement.
http://www.tepco.co.jp/en/press/corp-com/release/11091502-e.html

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110914_01-e.pdf more details about unit 2 cooling plan.

 

[zapperzero]

The blowers of the standby gas treatment system haven't worked since the blackout, so they aren't going to push anything up the stacks.

It's not like there isn't a permanent pressure differential between the bottom and the top of the stacks. I don't know if they are isolated or not, though.

 

[joewein]

It's not like there isn't a permanent pressure differential between the bottom and the top of the stacks.

Only if they are hot inside. Are they?

 

[zapperzero]

Only if they are hot inside. Are they?

Huh? No. It happens because they are quite tall and because the wind is faster at altitude.

 

[CaptD]

Anybody seen this site before, seems to have "new" info:
http://www.houseoffoust.com/fukushima/fukushima.html

 

[Rive]

Here is this new handout: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_01-e.pdf

Can somebody please explain it for me?

Ps.: They have a new core cooling plan: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_02-e.pdf

 

[SteveElbows]

Anybody seen this site before, seems to have "new" info:
http://www.houseoffoust.com/fukushima/fukushima.html

Discussed here plenty in the past, not so much recently due to a lack of new material.

In my opinion the site was only useful when people were craving imagery, understanding of plant layout etc. But a somewhat hysterical interpretation of certain images, including faulty and credibility-eroding speculation about various 'smoke' events on the webcam, and fact-free jumping to conclusion about reactor 4 building 'leaning', significantly reduced the use that those with a scientific interest have for that site.

 

[SteveElbows]

Here is this new handout: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_01-e.pdf

Can somebody please explain it for me?

I can only provide a simple interpretation at this stage.

They have tried to learn more about the state of the bottom of reactor 1 vessel by using the system that tells them about the position of the control rods. But because they can't be sure what causes bad results, e.g. is it just wiring damaged or a more substantial destruction of some control rods, it seems hard to draw solid conclusions.

 

[zapperzero]

Ps.: They have a new core cooling plan: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110916_02-e.pdf

New cooling plan is: they have increased water injection rates, they plan on increasing them further via core spray system and have resumed injection of boric acid.

Things are looking up, yes?

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110915/index.html JAEA will present an analysis of the accident progression of unit 2 at the Japan Atomic Energy Society meeting held in Kitakyushu from 19 September. According to their findings, unit 2's meltdown and explosion on 15 March could have been avoided if water injection had been started 4 hours earlier, at 4 PM on 14 March instead of 8 PM. Because of circumstances such as some fire trucks being broken by unit 3's explosion, the start of the preparation work for unit 2's water injection had been delayed. Tepco asserts that "As we worked with the maximum effort under extremely severe conditions such as high radiations, it is not thought that we have been late to perform the water injection work". The head of JAEA nuclear safety centre, Masashi Hirano says: "Since the cooling of unit 2 reactor has continued for 3 days, there is time margin and sufficient possibility to prevent fuel damage. The behaviour of the operators and the circumstances of the preparation of water injection are important points of the accident investigation."

 

[CaptD]

RE: Increase water flow rates:
I believe that the increased water is an attempt to try and cool the Corium(s) before they make (in at least one case) contact with the Earth below the reactor structure!

The concept of safe shut down is nothing more than more Nuclear Baloney (NB) SPIN because the three (3) reactor vessels have holes in them with their Corium(s) outside the containments with highly radioactive water leaking into either the ground water and or the Pacific Ocean!

Pretty hard to achieve SAFE shutdown when the Corium is outside the Reactor and continuing to fission on it own! This is nothing more than Radioactive SPIN, by TEPCO...

http://mdn.mainichi.jp/perspectives/news/20110909p2a00m0na016000c.html
snip
As a radiation metrology and nuclear safety expert at Kyoto University's Research Reactor Institute, Hiroaki Koide has been critical of how the government and Tokyo Electric Power Co. (TEPCO) have handled the nuclear disaster at the Fukushima No. 1 nuclear plant. Below, he shares what he thinks may happen in the coming weeks, months and years.

The nuclear disaster is ongoing. Immediately after the crisis first began to unfold, I thought that we'd see a definitive outcome within a week. However, with radioactive materials yet to be contained, we've remained in the unsettling state of not knowing how things are going to turn out.
...

Recovering the melted nuclear fuel is another huge challenge. I can't even imagine how that could be done. When the Three Mile Island accident took place in 1972, the melted nuclear fuel had stayed within the pressure vessel, making defueling possible. With Fukushima, however, there is a possibility that nuclear fuel has fallen into the ground, in which case it will take 10 or 20 years to recover it. We are now head to head with a situation that mankind has never faced before.

 

[Borek]

The concept of safe shut down is nothing more than more Nuclear Baloney (NB) SPIN because the three (3) reactor vessels have holes in them with their Corium(s) outside the containments

Any reliable sources to that claim?

 

[CaptD]

Here are some links that I can find right now, plus the Fairewind Assoc. Updates...:
 http://www.fairewinds.com/

 http://mdn.mainichi.jp/mdnnews/news/20110828p2a00m0na002000c.html


http://www.tokyotimes.jp/post/en/1665/Fukushima+cleanup+could+take+a+century+Nature.html

 http://fukushima-diary.com/

 http://www.guardian.co.uk/commentisfree/2009/may/28/who-nuclear-power-chernobyl

 

[Borek]

Here are some links that I can find right now

Regardless of whether these are reliable sources, none states anything about state and position of the corium.

 

[CaptD]

RE:Corium(s) Position
I was not saying that I have direct knowledge of the location of any of the three corium(s),
but rather I was giving my opinion based upon my understanding of the info I have read and my best guess.

I would be interested in what others have to say about the corium(s) and their proximity to the Earth and water table/ocean interface below the reactor complex...

Thanks

 

[Cire]

RE:Corium(s) Position
I was not saying that I have direct knowledge of the location of any of the three corium(s),
but rather I was giving my opinion based upon my understanding of the info I have read and my best guess.

I would be interested in what others have to say about the corium(s) and their proximity to the Earth and water table/ocean interface below the reactor complex...

Thanks

How about this opinion. The fuel pellets are scattered on the bottom of the RPV's. There is little to no corium produced. The RPV's are leaking at the various seals, flanges but not breached in any other way.

For those that want to argue corium melted through the bottom you need to answer this for me.

How do you get temperature readings from a sensor on the bottom of the RPV that would have melted off (wires) and destroyed the thermocouple before the RPV failed?

 

[CaptD]

Think penetration failures on yet another part of the reactor itself; one side may be intact while yet another is "gone"... and this may be responsible for "The Fuky Effect", where the temperature graph zooms up then down!
http://atmc.jp/plant/rad/?n=1
Thanks for asking!

+
This from April 20th Japan nuclear agency finally admits fuel has melted in reactors 1, 2 & 3 http://enenews.com/japan-nuclear-agency-finally-admits-fuel-melted-reactors-1-2-3
+
Reactor Rod images:
http://www.houseoffoust.com/fukushima/rods.html

 

[Astronuc]

Reactor Rod images:
http://www.houseoffoust.com/fukushima/rods.html

Those are not images of fuel rods. Fuel rods are not that large. What they show is someone's uninformed opinion.

 

[Cire]

Think penetration failures on yet another part of the reactor itself; one side may be intact while yet another is "gone"... and this may be responsible for "The Fuky Effect", where the temperature graph zooms up then down!

How does molten corium move laterally out of the side of the RPV, melting through several inches thick steel wall but not fall through the thin perforated core plate?

There are plenty of papers modeling corium migration to the RPV bottom. Can you point to one where corium exits from the side?

Be careful reading into news reports when the term "melted" is used or "meltdown". Having fuel pellets melt through their cladding and fall down into the RPV is considered a meltdown. It's also something very different then the elephants foot from Chernobyl.

 

[MiceAndMen]

Anybody seen this site before, seems to have "new" info:
http://www.houseoffoust.com/fukushima/fukushima.html

Discredited. Fantastical rumor mongering and unsubstantiated speculation. If the site had paid advertisemets it would be the Fox News of Fukushima. But there are no ads there so it's more like Tinfoil Central.

Hey, Nancy, is building 4 still leaning? What do your inside on-site sources say?

 

[CaptD]

Melted Fuel at Fukushima May Have Leaked Through, Yomiuri Says
By Go Onomitsu - Jun 6, 2011 11:02 PM PT
http://www.bloomberg.com/news/2011-06-07/melted-fuel-at-fukushima-may-have-leaked-through-yomiuri-says.html
snip
The melted fuel at Tokyo Electric Power Co.’s Fukushima Dai-Ichi nuclear power station may have leaked through the pressure vessels of the Nos. 1 to 3 reactors, the Yomiuri newspaper reported.
The Japanese government will submit a report to the International Atomic Energy Agency that raises the possibility the fuel dropped through the bottom of the pressure vessels, a situation described as a “melt through” and considered more serious than a “meltdown,” according to the report, which cited the document.