Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[jensjakob]

Containment Integrity study:
http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6906/cr6906.pdf

 

[AntonL]

Fascinating analysis and discussions on here.
The containment explosion hypothesis seems a likely explanation for the multiple explosions heard during the reactor 3 event. ie pop 1 being the pressure vessel, pop2 being the primary containment, and then pop 3 being the unpressurised hydrogen in the roof void. Although I would not have expected such large durations between each pop, and there are no visible signs of 3 independent explosions.

echos - not three explosions

To add another area of curiousity, has anyone considered what the grey area that appears to have emanated from reactor 3?

Side of cut away hill plastered with debris

And did I read that the oxidation reaction with zirconium and steam produced hydrogen and oxygen? Someone correct me if I am wrong please.

Yes correct - hot zirconium and steam will extract the oxygen from the H20 releasing the H2

Hydrogen for Unit 1 and 3 produced in reactor and leaked into the building.

Unit 4 Hydrogen generation is a mystery to me as TEPCO always claimed that SFP had water in it so how did fuel rods get partly exposed to generate steam and heat to allow the oxyidizing reaction of zirconium to and what caused a self extinguishing fire twice in unit 4.

 

[Maxion]

Unit 4 Hydrogen generation is a mystery to me as TEPCO always claimed that SFP had water in it so how did fuel rods get partly exposed to generate steam and heat to allow the oxyidizing reaction of zirconium to and what caused a self extinguishing fire twice in unit 4.

There is a plausible explanation to unit four IMO. TEPCO claimed the SPF had water in it. Let's say it does. Unit four was under maintenance during the disaster and the fuel had been removed from the reactor to the SPF. Since I am not at all familiar to the procedures taken during maintenance or refueling of a reactor this is speculation but could there have been fuel rods in the equipment storage pool? IF there was fuelrods there then that might explain fuel rods oxidizing with there still being water covering the fuel rods in the SPF ;)

 

[jensjakob]

Good point:
http://lewis.armscontrolwonk.com/archive/3640/fukushima-reactor

Immediate after the shutdown,there still needed for quite a while to be removed residual heat compared to 100% power production.

Remember, even though that after shutdown residual powergeneration went to 7% - there still was the heat a few minutes ago from 100% power generation (or what ever level they were blasting along at)

 

[jensjakob]

"Drywell head is predicted to unseat at 27 psig" (page 5, upper part)
http://www.osti.gov/bridge/purl.cov...F5E975EF06A9A903D0D15E6?purl=/5630475-EX87x5/

Holy cow - that is about just a FEW BAR!

"Just a few square inches are enough to relieve pressure"
"Due to the large surface of the drywell head, leaks are easy"

If that is true - then there is a SERIOUS flaw in the BWR 1 (and otherrrs?) design - and a quite plausible documentation for TCups theory.

That is quite bad - so I kindly request you to do your best to dis-prove this theory, we need to see if we have hit bulls-eye.

Found also this detail diagram of drywell head fastening:
http://www.ansn.org/Documents/Training/PSA%20Level%202%20(Probabilistic%20Safety%20Assessment)/M5%20%20Containment%20Perform.ppt#292,17,Example: BWR Drywell Head Seal

 

[M. Bachmeier]

echos - not three explosions


Side of cut away hill plastered with debris



Yes correct - hot zirconium and steam will extract the oxygen from the H20 releasing the H2

Hydrogen for Unit 1 and 3 produced in reactor and leaked into the building.

Unit 4 Hydrogen generation is a mystery to me as TEPCO always claimed that SFP had water in it so how did fuel rods get partly exposed to generate steam and heat to allow the oxyidizing reaction of zirconium to and what caused a self extinguishing fire twice in unit 4.

In an interview with an employee working in unit 4, he described water (in large quantities) splashing out of the spent fuel containment pool at the time of the earthquake (said he was covered with it and thought he was going to die). Also, several pieces of equipment that were brought into the building (for inspection purposes) were knocked to the ground. There was definitely water lost at the time of the quake.

 

[|Fred]

Hey,
I'll concede that I'm out of my league in here, None the less couldn't be one way of looking at the issue to look at the kind of radioactivity (isotopes) we are dealing with ?

If I'm not mistaken, the radioactivity that we measure at 30Km did not arrive by it self and seems to be increasing. In order for those fission material to travel they need to fly hence to be Gaseous / Soluble in watter => Steam / Metal ionised => Smoke

We are seeing vapor for the past days
We are seeing increasing radioactivity in the 30km zone
We are seeing iodine radiation in the 30km zone
Iodine isotope is water soluble / Vapor "movable"
There has been no logged venting since the 15th
Iodine radioactive isotope has a small half live

Doesn't it make sens that the idodine that they are getting comes from the reactor 3 core rather than the spent fuel pool ? And since they did not vent R3 that it comes from the steam that is said to be SFP related?

 

[jensjakob]

Fred, interesting chain of action analysis.

If you're correct - we're facing a melting core in #3, that is venting to the outside :-(

I hope you're wrong - for the sake of the environment.

One hole I can see, the theory would need a leak from the reactor pressure vessel to the containment bulding.

 

[Maxion]

Doesn't it make sens that the idodine that they are getting comes from the reactor 3 core rather than the spent fuel pool ? And since they did not vent R3 that it comes from the steam that is said to be SFP related?

Why would it have to come from the core rather than the SFP? The same rods are in the pools and according to Tepco the ponds have most likely been empty at some point in time. Remember Occam's razor. A simple theory is most likely the correct one, unless we have proof that it is more complex.

 

[Bez999]

@jensjakob: one would assume they continuously vent from the reactor vessel to the dry well, as that is in fact the cooling procedure going on with sea water. This venting ends up through the wet well also, as per the design. What is not according to design is any leaking of the containment through the dry well cap, a problem earlier encountered in this design (see report quoted above). In this case the seal of that cap may well have been further breached as per tcup's theory, and this would accord with the sort of steam plume we see above the no3 building, again see tcup's argument. So, while the officials say that no venting to the outside was necessary because the pressure dropped by itself, it may be that the containment is venting continuously anyway, which would also tie in with the ongoing radiation readings, and especially the presence of soluble iodine isotopes, which could presumably be transferred effectively through steam and water vapor.

 

[|Fred]

The one in the Core had one week (1/2 life) of decay while the one in the pool Have a lot more. Venting has been stopped for five days. Iodine radioactivity increase more than during wenting. It does make sens to get more with a less radioactive source?

 

[havemercy]

Hello to all,

I am a new visitor of this site and, first of all, i want to apologie for my poor level of english.

Here in switzerland and France we are a little lost with the F. situation and in particular regarding the information confirming or not the formation of a corium and in which reactor.

Some are saying, from the TMI situation, that coriums are actualy presents in reactor 1, 2 and 3, that they are going through the ciment structure of the reactors (probably 1 meter per 24 hour) and that the big threat is now the contact of it with groundwater in the soil.

We also wander what occurred to the main used fuell vessel that should contain a lot of material. Many thanks in advance.

havemercy

 

[jensjakob]

More studies on BWR Mark1 failures:
http://www.osti.gov/bridge/product.biblio.jsp?query_id=1&page=0&osti_id=6980202&Row=1

A very nice source for many good factual background documents:
http://sustainableenergytoday.blogspot.com/2011/03/post-31-bwr-severe-accidents-primer.html

 

[TCups]

Fascinating analysis and discussions on here.
The containment explosion hypothesis seems a likely explanation for the multiple explosions heard during the reactor 3 event. ie pop 1 being the pressure vessel, pop2 being the primary containment, and then pop 3 being the unpressurised hydrogen in the roof void. Although I would not have expected such large durations between each pop, and there are no visible signs of 3 independent explosions.

To add another area of curiousity, has anyone considered what the grey area that appears to have emanated from reactor 3?

http://patrick.reformstudios.com/p.jpg

The additional "booms" are very likely echoes. The gray debris result from two of the side panels of building three blowing out, striking the smaller building behind, and scattering debris on the steep slope of the berm, behind. I think I posted that earlier when we were looking at the holes in the top of the steam turbine buildings.

 

[fusefiz]

If water has been covering the fuel in the reactor 4 pool, what could have generated the hydrogen?

I have been reading this thread for most of the week and wondering myself. Today I discovered the French analysis, which is the most coherent treatment I have found. I have almost no time now, so I will just briefly pass on a few of their conclusions. Sometime during the next 24 hours I hope to write more.

The French conclude that the reactor 4 pool has been covered by water. They believe the explosion was due to hydrogen which was created in the fuel pool by radiolysis. This hydrogen and oxygen could accumulate in the building since the ventilation equipment that usually handles this problem was not powered.

They calculate 3MW of heat generation in this pool, which should be boiling or start to boil soon. If this water is boiled off and not replenished, they expect this fuel to burn, melt into corium, and eat through the pool bottom, accompanied by a MAJOR release of radiation.

The French analysis also concludes that the "biological shield" (i.e., the concrete plug) is missing in reactor 3 (but still present in reactor 1, where the roof has apparently been completely blown away leaving a clear view of the refueling deck). As I understand it, under this shield there would still be the drywall head, and under that would be the cap on the reactor pressure vessel.

From an analysis of the damage in the reactor 3 building, the French suggest that the spent fuel pool may have suffered major structural damage which, in the worst case, would leave only 1 meter of water over the top of the fuel rods (this damage would be in addition to any possible leaks).

So suppose there is reduced shielding over the reactor 3, and possibly reduced shielding over its spent fuel pool. Could this explain the strong radiation detected by the helicopters over the reactors? I.e., this would be gamma radiation from reactor 3 and possibly its pool, not from the reactor 4 pool. If that is the case, I believe some of this gamma radiation would be also be reflected down to Earth around the reactor by the damaged structural beams. And if this is the case, reactor 3 will be difficult to deal with and eventually clean up.

Here is a link to an English article which communicates a bit of their analysis,
| http://blogs.wsj.com/washwire/2011/03/17/did-nrcs-jaczko-misspeak/

The French news releases can be found here (1 or more per day, PDF files):
| http://www.irsn.fr/FR/Actualites_presse/Actualites/Pages/actualite.aspx

The following press release contains, at the end, a photo annotated with some of their conclusions (all in French, their English version of this website does not have translations of these press releases):
| http://www.irsn.fr/FR/Actualites_pr...Seisme-Japon_Point-situation-20032011-06h.pdf

 

[TCups]

No, the seal of the primary containment is the cap of the steel containment vessel. There should be no pressure proof anything above that. I'm not sure where you're getting this seal of the transfer chute from, that seal is most likely no more secure than the concrete plug.

Maxiom: you didn't read the reference in my original "DEBUNK THIS" thread. Here it is again:

http://allthingsnuclear.org/post/3964225685/possible-source-of-leaks-at-spent-fuel-pools-at

and the seal issue in the transfer chute area is more about where the most likely point of failure would be if there were a hydrogen + oxygen + steam blast coming from the primary containment, outside of the reactor vessel. The most obvious weak spot in the top of the containment would be the fuel transfer chute or a section of the plug or perhaps some combination of both.

 

[TCups]

In an interview with an employee working in unit 4, he described water (in large quantities) splashing out of the spent fuel containment pool at the time of the earthquake (said he was covered with it and thought he was going to die). Also, several pieces of equipment that were brought into the building (for inspection purposes) were knocked to the ground. There was definitely water lost at the time of the quake.

Well, Duh?! Guess I overlooked sloshing as a potential cause of coolant loss. Add that to the boiling water and leaking seal mechanisms for uncovering unspent fuel rods in Unit 4. Giving new meaning to a "shake and bake" etiology for the hydrogen explosion in Unit 4.

 

[georgiworld]

First off, I'd like to thank all the contributors to this forum for giving such thoughtful and insightful opinions regarding Fukushima. I have only one question. My daughter works in Tokyo and finally had enough and flew home on Thursday.

She works for a large bank and is using vacation time because they believe everything is under control. She claims they are receiving the most accurate information and would never jeopardize the health of its workers. I have my doubts about that.

She is supposed to return to Japan at the end of the month and my question is, should I allow her to return or try to persuade her that it is too dangerous.

Thanks to all

 

[TCups]

Fred, interesting chain of action analysis.

If you're correct - we're facing a melting core in #3, that is venting to the outside :-(

I hope you're wrong - for the sake of the environment.

One hole I can see, the theory would need a leak from the reactor pressure vessel to the containment bulding.

Jens: while there could be a leak from the reactor to the primary containment, there could have also been active venting from the core to the primary containment by the operators in order to spare the reactor vessel, correct? And isn't the whole design of that torus pool at the bottom with all those vents intended to be a venting system? Sure looks so, from the diagrams. And if so, it didn't work very well.

Fred: I can't argue with your reasoning.

 

[Borek]

Here in switzerland and France we are a little lost with the F. situation and in particular regarding the information confirming or not the formation of a corium and in which reactor.

Some are saying, from the TMI situation, that coriums are actualy presents in reactor 1, 2 and 3, that they are going through the ciment structure of the reactors (probably 1 meter per 24 hour) and that the big threat is now the contact of it with groundwater in the soil.

This is all pure speculation, picked from the nose. We don't know details of what is happening inside, but so far there are no hard facts supporting meltdown.

 

[Borek]

She is supposed to return to Japan at the end of the month and my question is, should I allow her to return or try to persuade her that it is too dangerous.

At the moment - just wait, as situation is not clear yet. So far it doesn't look like being in Tokyo is really dangerous.

 

[TCups]

This is all pure speculation, picked from the nose. We don't know details of what is happening inside, but so far there are no hard facts supporting meltdown.

Borek:

Agreed, but . . .

1) My entire train of thought was about how what has happened at unit 3 might happen without the core melting down.

2) The pictures and videos tell a story, if we are smart enough to read it, and that visual information is pretty detailed and is entirely objective. Most of my speculation has been picked from the pictures, not my nose, respectfully.

 

[M. Bachmeier]

Well, Duh?! Guess I overlooked sloshing as a potential cause of coolant loss. Add that to the boiling water and leaking seal mechanisms for uncovering unspent fuel rods in Unit 4. Giving new meaning to a "shake and bake" etiology for the hydrogen explosion in Unit 4.

Just a dumb follow up... But if that employee did get doused with water from the spent fuel rod containment, wouldn't he be just a bit radioactive?

He was being interviewed with his identity hidden. (NHK)

 

[TCups]

Just a dumb follow up... But if that employee did get doused with water from the spent fuel rod containment, wouldn't he be just a bit radioactive?

He was being interviewed with his identity hidden. (NHK)

I am the wrong person to answer, but I will answer anyway. If the water in the SFP were absolutely pure, it would not be highly radioactive, I believe. The radioactivity would have to come from

1) gamma radiation passing through the water, or
2) radioactive contaminants in the water (dissolved radioactive isotopes or impurities that were "activated" by neutron bombardment)

 

[Borek]

Most of my speculation has been picked from the pictures, not my nose, respectfully.

Nose picking part was referring to the post I was replying to (quoted part), not to your posts.

At the same while I agree that there is some information that can be distilled from the pictures, I feel like general trend in this thread is to draw too far fetched conclusions from partial information.

 

[havemercy]

In TMI, correct me if I am wrong, the cooling of the water has been stopped for 16 hours, and the results was 48% of melting core and 22 % of the corium beeing down in the steel tank, which was attacked over three inches thick (3/5).

From what i understood, the japanese reactors has not been cooled from the interior since a week and, in any case, the water cooling systeme requests pressure that has been lost since the accident.

Is this not enough to conclude to a meltdown ?

 

[AtomicWombat]

Lochbaum's claims about a Zircaloy fuel cladding fire have been debunked... simply by actually doing a simple experiment.https://www.youtube.com/watch?v=x__2yWx9zGY

No actually, the heating has been done in (effectively) dry air, not in saturated steam. The reaction rate is much faster in the steam at high temperature.

http://en.wikipedia.org/wiki/Zircaloy#Oxidation_of_zirconium_by_steam"

Section 6 of this (large ~ 10 MB) NEA report deals with this question in detail:

https://www.oecd-nea.org/nsd/reports/2009/nea6846_LOCA.pdf"

Some excerpts:
"In the temperature range of interest in LWR conservative accident analyses, the Zircaloy is highly reactive with steam and the high temperatures and exothermicity of the reaction introduce considerable experimental difficulties in determining the kinetics of the reaction."

[Me] The difficulty in studying the reaction is because it is strongly exothermic. Reaction kinetics are usually studied under isothermal (constant temperature) conditions. So the heat must be removed as quickly as it is produced.

"Leistikow and co-workers have also investigated the kinetics of Zircaloy-steam reactions after times much greater than previously reported, i.e. for times up to 25 hours. The temperature range of investigation was from 700°C up to 1 600°C and since the Zircaloy test pieces were from cladding tube the times at higher temperatures were limited to those at which complete consumption of the tube wall occurred, e.g. ~6 min at 1 600°C and ~40 min at 1 500°C."

So at 1 500°C it takes 40 minutes to burn the tube entirely in steam. At 1600°C it takes 6 minutes. How long will it take in 1700°C? How about 1800°C? Remember that for each atom of zirconium oxidised in this reaction, two molecules of H2 are produced. And a little hydrogen goes a long way when air is present.

Effectively we can regard the reaction to be Zr + O2 => ZrO2 with water (steam) as the catalyst massively increasing the rate of the reaction.

 

[TCups]

In TMI, correct me if I am wrong, the cooling of the water has been stopped for 16 hours, and the results was 48% of melting core and 22 % of the corium beeing down in the steel tank, which was attacked over three inches thick (3/5).

From what i understood, the japanese reactors has not been cooled from the interior since a week and, in any case, the water cooling systeme requests pressure that has been lost since the accident.

Is this not enough to conclude to a meltdown ?

I will take a layman's stab at answering.

First, it is probably not appropriate to suggest that because something happened at TMI or Chernobyl, that the same thing is happening here. I am not sure, but I think the designs of TMI and Fukushima were different. I know Chernobyl was a graphite pile that exploded and burned for days ejecting MASSIVE quantities of radioactive waste high into the air and that was many orders of magnitude worse than anyone's worse case scenario at Fukushima -- even in the most far-fetched speculative scenarios.

Second, I am not an expert on TMI, though I did live through it. TMI's accident happened with the reactor operating, I believe. Fukushima has had multiple accidents, all that occurred with reactors already shut down (control rods inserted) after the earthquake. These occurred hours later, after the quake took out the power grid, after the tsunami took out the diesel generators, and after the back up batteries on site were depleted. These occurred as a consequence of loss of water to cool the residual heat in the cores and in the rods in the SFPs, not as a consequence of failing to properly cool an operating reactor.

As far as I know, the potential consequences of uncovering fuel rods in a reactor that is "hot" (either operating at power or immediately after inserting control rods) are far more dangerous than the consequences of uncovering fuel rods in a shut down reactor with control rods in place for hours or days before coolant was lost, and the timeframe before something really bad happens -- a complete "meltdown -- would be very different.

"Melt down" is being used loosely, I think. Uncovered fuel rods, including spent or unspent fuel rods in the cooling pools or unspent fuel rods in the shut down cores of the reactors can heat up, oxidize, produce hydrogen and oxygen, and cause secondary explosions without "melting down". Rods in the shut down reactor's containment vessels can partially melt without "melting down" and breeching the reactor vessel or primary containment. None of the fuel in the SFP or reactor cores at Fukushima appear to be in danger of "going critical". Explosions within the primary containment can apparently occur without a complete breech of the reactor vessels or melting of the cores.

Someone will surely correct me if any of those statements are untrue or flawed. Borek's admonition to be very careful speculating about events far more disastrous than have yet occurred or are ever likely to occur serve no useful purpose. But there remains a lot of control, containment and clean up that will have to be done at Fukushima, no doubt about it.

 

[havemercy]

Ok, thank you for your time and response.

 

[AtomicWombat]

Brief background: Am using info here and elsewhere to try to help 3 families in Tokyo decide what moves to make, if any. One father has already moved his family (wife & 2 kids) down to Ehime prefecture on Shikoku, a decision he made early on before input from me. He's desperate to move them out of the country altogether, but can't. Another with family I haven't heard from since 14th, so I assume he's also left Tokyo and can't get to a computer. The third is teacher of a well-known young pianist who has 3 recitals imminent in Japan and then another at the Japan Festival in New York April 3rd, so they have little option but to stay with the pianos in Tokyo!

A cousin of mine plus (Japanese) family fled Japan Tuesday on a flight booked last year. They are so relieved to be out. Ironically they were worried about the predicted Great Tokai quake, supposed to be coming in the south. This quake in the north was apparently quite unexpected.

I'm one of the contributors to this forum who suspects the situation is much more serious than the authorities are admitting. For example I think there is good evidence that the spent fuel rods in reactor 4 have already melted down, and that reactor 3 has been breached by the huge internal explosion.

Whilst the authorities are down-playing the situation, their management of the potential health consequences appears more reasonable. The 20 km exclusion zone and 20-30km stay indoors zone are probably a compromise between the 80 km zone recommended by the US & other nations, and the practical implications of relocating millions of many people. Chernobyl revealed the need to take potassium iodide tablets (esp for children), but the vast majority of thyroid cancers were not fatal. The spread of radiation after Chernobyl was much more efficient due to the graphite core fire.

I think the authorities are down-playing the situation precisely to avoid the kind of panic you are describing. However, I see no need to evacuate Tokyo. Residents in Tokyo will only be exposed to high radiation if a large cloud of radiation (like that possibly produced on Monday 14 March) blows directly over the city and it then rains on the city. I have no doubt everyone will be ordered to stay inside should such an event occur. Storm events passing over Fukushima towards Tokyo may also result in warnings to stay indoors.

Radiation creates anxiety & panic because it is invisible, its effects are insidious & long-term, and because a high level of the education is required to understand the risks and keep them in perspective.

There is likely to be a long-term exclusion zone around Fukushima, but the the other losses caused by the tsunami will eclipse Fukushima by far.

 

[Reno Deano]

Thoughts, the hydrogen would not explode in a oxygen deficient atmosphere, such as within the primary containment(?). Therefore, the clould egressed out of the primary containment via piping opened for venting, built up in the upper levels of the reactor building and then exploded. Which would be above the SPF and the Primary Containment Plug. The blast would take the avenues of least resistance-the sheet metal walls of the upper part of the building. Just some idle thoughts.

 

[AntonL]

An http://www.slideshare.net/iaea/4-briefing-radiation-protection-20-03-2011a" regarding radiation levels

and

ongoing http://www.mext.go.jp/english/" published by Japanese government.

 

[AtomicWombat]

For one, post #526 quoted another post which disagreed with the assertions. Two, the radiation levels at Fukushima are not indicative of corium release. The following chart compares radiation levels at Fukushima next to known corium releases:

http://upload.wikimedia.org/wikipedia/en/f/fd/Fukushima_map.png

What it shows is that one reactor from Chernobyl was releasing orders of magnitude more radiation than four damaged reactors at Fukushima. This displays a high degree of confidence that no corium has escaped into the environment.

The post I quoted disagreed with the whether it was correct to model the radiation as I had done. The author did not offer an alternative way to calculate radiation 2 metres from to a hypothetical source near the ground given the readings at 100 and 300 metres.

I think the chart you linked to is wonderful - it captures an enormous amount of information is a clear concise form. An excellent example of the visual display of information. Odd that it stops on 16 March. Yes there appear to be about 2 orders of magnitude difference between this crisis and Chernobyl, but note two things: 1) that this crisis is not over yet; and 2) in Chernobyl radiation was distributed much more efficiently by smoke from the reactor fire.

I suspect the source of the time series is this chart at the German GRS, Gesellschaft fur Anlagenund Reaktorsicherheit (Organoisation for Social and Nuclear Safety):
http://www.grs.de/sites/default/files/images/Radiation-Data__20110320-1715.pdf"

Note that MP refers to as Messpunkt or "measurement point" in German.

See the upper left of the German plot (linked above). All 8 numbered MPs are on the perimeter of the site, 1 km or more from the reactors. The main gate (Haupttor) is 1.0 km from block 2 (similar to blocks 3/4) not 200 metres in the plot you link. This distance change alone reduces the distance between Chernobyl and Fukushima to just over an order of magnitude, since most of the information in the chart is from the main gate.

Since 18 March (till 21/3) only discontinuous measurements at the West Gate (Westtor) and main building (Haupttor) have been recorded. At the main building - 500 metres from reactor 2) they have been between 3 and 5 mSv/hr.

I suspect, but cannot prove that the radiation sources at Fukishima are exposed, but still much more localised than they were at Chernobyl. The Fukishima core peak (1000 mSv/hr) is from the vicinity of reactors 3 & 4 not from the core, unlike the Chernobyl reading.

So unless more detailed radiation measurement are available, I see no reason to be confident that corium has not escaped. I am confident that we do not (yet?) have widespread contamination of the site with radioactive material from the reactor core, as occurred in Chernobyl.

 

[AntonL]

T
I suspect the source of the time series is this chart at the German GRS, Gesellschaft fur Anlagenund Reaktorsicherheit (Organoisation for Social and Nuclear Safety):
http://www.grs.de/sites/default/files/images/Radiation-Data__20110320-1715.pdf"

Note that MP refers to as Messpunkt or "measurement point" in German.

This radiation plot is very interesting, Note the peak on of 3mSv on the 20 March

From http://www.jaif.or.jp/english/index.php" reports I extracted pressure values for the containment vessel unit 3 and in () reactor pressure

20/3 16:00 .290 MPa (0.119 MPa_g)
20/3 04:30 .340 MPa (0.180 MPa_g)
20/3 01:10 .280 MPa (0.113 MPa_g)

19/3 06:10 .045 MPa (0.005 MPa_g)

18/3 14:45 .155 MPa (0.005 MPa_g)
18/3 08:00 .150 MPa (0.005 MPa_g

17/2 No DataTEPCO did give notification to vent and then said it was not necessary!
Did the containment vessel self vent?
the radiation data seems to indicate this but what is radio active material doing in the the containment vessel.

But more disturbing on 19th March the containment vessel pressure was 0.045MPa
at 06:10 in the morning the only figure published on the 19th and reactor pressure was similarly low!
However on the day before 18th CV pressure was 0.55MPa
What happened that pressure fell and rose so dramatically in such a short time?
Has the 4mSv peak on the 19th got something to do with it? and
Was the CV vented in the afternoon of the 18th (5 mSv Peak)

 

[georgiworld]

According to JAIF "The pressure of the containment vessel increased at unit-3 in the morning of Mar. 20th . The pressure became stable at higher level after this increase."

This seems to conflict with the data extracted by Anton

 

[|Fred]

@Wombat
Well if I'm not mistaken in your calculation you assume that the radiation level measure taken at x meters are "induce" from the radiation source hence your reverse invert square law calculation.

In my opinion you are likely making a false assumption / interpretation : The radiation source are more likely the volatile isotope in the air , at least for the most part.


ps: to make my self more understandable your calculation would be right if let say you had a pile of radioactive isotope outside your windows, you were in your house and wanted to know how radioactive this pile was taking a measurement from a distance. But what we have here is a window leaking and wind blowing some of the stuff to the inside..

 

[AntonL]

This is what steel reinforcement rods (rebar) left behind after an outward blast with the concrete blown away. They are bent and bow outward.

I agree and pretty obvious as bits of concrete are still hanging to it, but note that the re-bars are dull, they do not reflect light

On the other hand, this is what I think a smashed fuel rod assembly within the rubble after the blast might look very much like. Comments?

after initial dismissal I now lean slightly towards TCups statement. These rods are shiny, reflect the light and one also notes that the rod-ends have different light reflecting characteristics as the rod itself, possibly die to shaping. There seem to be two different rods involved of different diameter any explanation for this?

below a picture of fuel rods (not necessary of same type as used in Fukushima)

 

[|Fred]

Furthermore, They stated that they are going to use tanks to clear some highly radioactive debris. Where are those suppose to come from if Fuel Rod Are still all sitting nicely in the Pool , what could they be ?

 

[AntonL]

Copied from http://english.kyodonews.jp/news/2011/03/79925.html"Grayish smoke was seen billowing from a building that houses the No. 3 reactor
of the troubled Fukushima Daiichi nuclear power station on Monday, plant operator
Tokyo Electric Power Co. said.

After the smoke was spotted at the southeast of the building around 3:55 p.m.,
TEPCO said it had temporarily evacuated its workers from the site as it assessed the situation.

The amount of smoke later decreased, TEPCO added.
Tepco confirms soke from South East Corner of building which is the spent fuel pool

PS:
The same site (Kyodo) is also running a banner that:no increase in radiation is detected, time stamped 5:49PM
Smoke billowing above spent nuke fuel pool at No. 3 reactor: agency (time stamped 5:59PM)
No change seen in pressure inside containment vessel of reactor No. 3 (time stamped 6:11PM)

 

[|Fred]

ok Bad news ... Smoke coming out of reactor n°3 at 17:15 JSP , workers had to be evacuated, cause of smoke unknown-ed, no work done on n°3 today Smoke not steam ... Smoke black then grey

sorry for double post we posted the same info simultaneously

edit: Japanese Authorities ,report no augmentation in radioactivity or change in pressure (where?), therefore they do not conclude yet that the Smoke comes from the combustion of radioactive materials.

edit 19:00 JST no more smoke

 

[jensjakob]

ok Bad news ... Smoke coming out of reactor n°3 at 17:15 JSP , workers had to be evacuated, cause of smoke unknown-ed, no work done on n°3 today Smoke not steam ... Smoke black then grey

sorry for double post we posted the same info simultaneously


edit: Japanese Authorities ,report no augmentation in radioactivity or change in pressure (where?), therefore they do not conclude yet that the Smoke comes from the combustion of radioactive materials.

What are the physics of moving radiation?
I understand that e.g. the radiation from the SFP are NOT measured on groundlevel near the NPP, since the walls of the SFP catches the radiation, so I would REALLY like to read a measurement of radiation above the SFP. That could be HUGE numbers.

And the next thing - the steam from the SFP, what kind of radioactive particles will it carry upwards? Propably near nothing.

The problem will rise the moment fuelrods are breached, and e.g. burned, so that radioactive particles are carried with the ashes and fumes out of the SFP, and at some time will fall down again, and radiate.

Can someone update me on the physics involved?


B'regards
Jens Jakob

 

[jensjakob]

Cooling/Electricity update:
But electricity was still not moving to Nos. 1, 2, 3 and 4, because the March 11 mammoth earthquake and subsequent tsunami -- including seawater that had rushed into the reactors -- had damaged numerous pumps and other apparatus. The Tokyo Electric official said that spare parts were being brought in, so that everything could work again.

http://www.cnn.com/2011/WORLD/asiapcf/03/21/japan.nuclear.reactors/index.html?hpt=T2

 

[AntonL]

Kyodo News banner headlines:

NEWS ADVISORY: Grayish smoke above No. 3 spent nuke fuel pool stopped: agency (19:21)
BREAKING NEWS: Smoke also seen at Fukushima plant's No. 2 reactor: agency (19:16)

 

[TCups]

I tried last evening, for a good hour, to confirm from any independent source, the exact layout of the floor plans of any of the units at Fukushima. I believe the visual assessment form the photographs is probably correct, but it conflicts with at least one of the models I have seen shown on a Japanese news video.

The best schematic drawings show the steam turbine plant in a different orientation relative to the reactor building.

I understand that difference of orientation is not necessarily significant, but does this drawing of the reactor building seem to correlate with the statement that the SFP is on the southeast corner at Fukishima Unit 3 & 4, and does it fit with what is visible on the photographs of the damaged facilities?

Does anyone have a better source for the actual "anatomy" of what the Fukishima facility is supposed to be, rather than a stylized schematic? A blueprint or floor plan would certainly help to be able to draw more informed conclusions about what is seen.

Thanks.

 

[jensjakob]

TCups, that is a late version containment - it hasnt got the Torus.

But I read earlier today, in the the newsflash related to the grey smoke from #3, that the SFP is indeed in the south-east corner, so sofar you are spot-on with your analysis

 

[ndray]

Does anyone have a better source for the actual "anatomy" of what the Fukishima facility is supposed to be, rather than a stylized schematic? A blueprint or floor plan would certainly help to be able to draw more informed conclusions about what is seen.

Thanks.

You can have a look at this view of the Oyster Creek Facility which I think is very similar to the Fukushima facility.

http://img863.imageshack.us/img863/3206/reactor.jpg"

 

[TCups]

I agree and pretty obvious as bits of concrete are still hanging to it, but note that the re-bars are dull, they do not reflect light



after initial dismissal I now lean slightly towards TCups statement. These rods are shiny, reflect the light and one also notes that the rod-ends have different light reflecting characteristics as the rod itself, possibly die to shaping. There seem to be two different rods involved of different diameter any explanation for this?

below a picture of fuel rods (not necessary of same type as used in Fukushima)

The most "telling" feature to me was the apparent rigidity of the rods. If they were pipes or structural steel or part of the overhead crane and fuel handling machine, as someone suggested as an alternative hypothesis, they came through the blast remarkably un-bent.

 

[TCups]

You can have a look at this view of the Oyster Creek Facility which I think is very similar to the Fukushima facility.

http://img863.imageshack.us/img863/3206/reactor.jpg"

OK, Oyester Creek, but then I have to assume that the most identifiable feature in the Fukushima building after the blast -- the intact square hole where the fuel casks are lifted by the crane, has been cut away from this drawing, correct?

Also, a small portion of the gate connecting the primary containment to the SFP is shown near the bottom of the transfer channel or "chute". If the scale is correct, it greatly reinforces my contention that the path of least resistance of a blast originating in the primary containment, outside of the RV would be through that gate (even if there are 2 of them, which does not appear to be the case) rather than out the top of the plug.

Notice the design. It appears to me that the logic behind a relatively thin-walled (concrete+ steel, or steel?) gate is that there is a large volume of water behind it, which under normal conditions, would tend to greatly reinforce the backside pressure on the gate at that point. If so, then here is another major design flaw. The reactor containment is compromised if the spent fuel pool is more than a few feet low on coolant. I suspect that the original designers considered an empty SFP with a hot reactor an unthinkable event. If so, then they should re-think that one.

Also, it occurs to me that if the overhead crane were parked at the north end of the building, it's weight would tend to bend the north end wall inward if the south, east and west walls were blown out, accounting for the under-folded north wall girders in our current pictures of Unit 3.

My conclusion:
Loss of water in the SFP greatly compromised the integrity of the reactor containment and the containment of the rods in the SFP when hydrogen and oxygen gasses in the reactor containment exploded. The dark smoke in the latest news release is ominous. I now fear that they may now have lost both the reactor core and the primary containment.

Someone please refute that.

 

[Playbook]

About the usage of seawater and the problems it creates:

The Finnish Radiation and Nuclear Safety Authority STUK has contacted their Japanese counterpart. The STUK simulated the usage of seawater to cool down the reactor core in a series of tests in the early 90's. They concluded, that this prosedure should only be done for a very short period of time.

After the water evaporates it leaves the salt behind. When the salt solution becomes strong enough to crystallize it would block the core cooling circuit. (QUESTION: at what percentage does a salt solution form salt crystals) After this the salt is allmost impossible to remove and it would prevent the cooling of the core.

Now the Pacific Ocean has an average salt content of a 35 g / 1000 g of water
We assume that the reactor evaporates 2000 g (2 litres) water / second

therefore:

2 kg/s * 3600 s * 24 * 7 * 0.035 = ~42 tons per week or 6 tons a day !

That's definately a big issue at the moment. Could it be that the smoke coming out is from burning salt?

 

[AntonL]

Todays fire in reactor 3 see https://www.physicsforums.com/showpost.php?p=3200508&postcount=692" This is smoke not steam

edit: replaced image with clearer one