Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[TCups]

There is a Russian rhyme that beginning chess players learn. Something is lost in translation, I am sure, but the gist of the verse is that a knight on the side of the board is a bad thing. This because its power is reduced to 4 the 8 potential squares it could attack.

For nuclear accidents, specifically the one in Japan, it appears to me that a "knight on the side of the chessboard" is a good thing with respect to population density and the long term results of radioactive contamination. Not that contamination of the ocean is good, but it will tend to dilute and everything that goes into the ocean will lessen long term exposure to the high density population of the people of Japan.

If I am following the thread correctly, one of the big questions, if not THE BIG QUESTION is how quickly the cores will cool to a "cold shutdown" temperature and therefor, hopefully eliminate the need to constantly pump water at the current rates required to cool the cores until they reach a "safe" temperature. That timeframe is uncertain because of some question of 1) the accuracy of the temperature measurements being in question, and 2) the potential of re-criticallity and re-heating of the core material delaying the cooling.

Is there any "reasonable" estimate as to when sufficient cooling of the core(s) might be expected to occur and thus eliminate the need for continued high volume water cooling and permit consideration of some type of permanent containment of the core material?

 

[tsutsuji]

Assuming catastrophic loss of coolant/cooling ability, is there any way of designing a reactor to melt-safe?

Lately, Areva has been insisting on the following :

For example, the EPR™ reactor is equipped with a corium drainage area that collects the substance if the reactor vessel is cracked.
Several design studies have helped optimize the EPR™ reactor’s recovery system, which is a large metal structure that ensures the passive, rapid cooling of corium from above, below and the sides.
This recovery system is located in a dedicated chamber within the reactor: the corium recovery chamber.

François Bouteille, Tuesday, April 05, 2011 3:02 PM http://www.areva.com/ajaxpub/dialog/DetailQuestion.aspx?idQuestion=668

 

[Krikkosnack]

Potential dispersion of the radioactive cloud after a nuclear accident in Fukushima

http://energheia.bambooz.info/index.php?option=com_content&view=article&id=163:potential-dispersion-of-the-radioactive-cloud-after-a-nuclear-accident-in-fukushima&catid=60:video&Itemid=85&lang=it

source http://www.eurad.uni-koeln.de/
http://www.eurad.uni-koeln.de/index_e.html

 

[Krikkosnack]

about alpha and beta particle detections... listen to the 4:18 - 4:30 intervall


What does he means?

 

[tsutsuji]

For nuclear accidents, specifically the one in Japan, it appears to me that a "knight on the side of the chessboard" is a good thing with respect to population density and the long term results of radioactive contamination. Not that contamination of the ocean is good, but it will tend to dilute and everything that goes into the ocean will lessen long term exposure to the high density population of the people of Japan.

Would not offshore be even better ? Kind of "knight outside of the chessboard", or "anchored nuclear submarine" then, although perhaps a little less crazy than the "sail the hull to a deep ocean trench and sink it" idea at http://www.guardian.co.uk/science/the-lay-scientist/2011/apr/06/1 (a lot of funny ideas there)

Reading the following :

An interesting article providing some details of the first two days of the accident:

http://www.yomiuri.co.jp/dy/national/T110411004567.htm"

Would it not be possible to have heavy lift helicopters and diesel generators ready in a number of airbases around the country, hoping that at least one of them will be far enough and safe from the earthquake, and able to take off and fly to the damaged plant as soon as the earthquake strikes ?

 

[Astronuc]

Astronuc,

Thank you so much for all the information you have supplied during this past month.

This forum has been invaluable as I struggle to understand what all the data, and corrected data, and crazy theories, mean to everyone living near the nuclear plants -- and the future of nuclear power.

Your insights are great. And now I must also thank you for saying when the data points are simply puzzling. Sometimes the explanation is not clear...hopefully we'll get more data soon that will help us understand the situation on the ground better.

-- JustGuessing

P.S. A month in, how do you think they are doing? What are you most concerned about? C an you start to image the cleanup?

Like a lot of others outside of the area, I'm wondering about what's really going on, and what the situation is with each reactor. It doesn't help to have conflicting or wrong information, such as some misreported isotopes.

As someone mentioned on the previous page (post #3507), I'm also wondering about the other nuclides, e.g., Sr-90. BTW - Cs-134 has half-life of 2.065 yrs and Cs has half-life of 30.1 years, so Cs-137 is the more persistent radionuclide.

Half-lives of the iodines are:

I-131, 8.0252 days
I-132, 2.295 hrs
I-133, 20.8 hrs
I-134, 52.5 min
I-135, 6.58 hrs

See attached figure.

I'm certainly concerned about the continuing release of radioactive materials from Units 1-4. TEPCO needs to stop the releaes ASAP, and figure out how to establish a closed cooling loop, and subsequently a treatment plan to decontaminate Units 1-4, and ultimately dismantle them - or possibly entomb them in such a way to preclude additional release of radioactive material.

As for the nuclear industry, there will be reassessments of current plants with respect to structural integrity in the event of a severe accident, as well as preparedness for several natural events and combinations thereof.

New plants are considered to be safer with better containment designs and more passive cooling designed into the plant. As far as I know, the newer plants have emergency backups in more protected locations. Siting of new power plants will receive more scrutiny.

 

[gmax137]

...
If I am following the thread correctly, one of the big questions, if not THE BIG QUESTION is how quickly the cores will cool to a "cold shutdown" temperature and therefor, hopefully eliminate the need to constantly pump water at the current rates required to cool the cores until they reach a "safe" temperature. That timeframe is uncertain because of some question of 1) the accuracy of the temperature measurements being in question, and 2) the potential of re-criticallity and re-heating of the core material delaying the cooling.

Is there any "reasonable" estimate as to when sufficient cooling of the core(s) might be expected to occur and thus eliminate the need for continued high volume water cooling and permit consideration of some type of permanent containment of the core material?

'Cold Shutdown' is made of two words: cold and shutdown

'Cold' implies both a closed loop cooling and temperatures below 212 F (100C) - the water circulated through the core becomes 'warm' (ie, not boiling) and it is cooled by a 'cool' source (ocean or river or cooling tower).

'Shutdown' means the reactivity is less than unity (typically less than 0.95) even at the cold temperature (the moderating capability of water increases as the temperature is lowered - so you need more boron or more control rod at lower temps).

 

[biggerten]

There is a Russian rhyme that beginning chess players learn. Something is lost in translation, I am sure, but the gist of the verse is that a knight on the side of the board is a bad thing. This because its power is reduced to 4 the 8 potential squares it could attack.

In English it's "Knight on the rim is dim".

 

[Krikkosnack]

http://www.asahi.com/english/TKY201104060126.html

When the Fukushima No. 1 plant was being built, Japan was importing technology from the United States and learning from a more advanced nuclear power nation. The No. 1 plant was considered a "learning experience." A former TEPCO executive said, "The Fukushima No. 1 plant was a practice course for Toshiba and Hitachi Ltd. to learn about GE's design on a trial-and-error basis." With the exception of the No. 6 reactor, the other five reactors at the Fukushima No. 1 plant are Mark I boiling-water reactors developed by GE.

http://www.europe1.fr/International/Des-traces-de-strontium-autour-de-Fukushima-496411/
Des traces de strontium, un élément radioactif produit par la fission nucléaire, ont été trouvées dans les sols et dans des plantes près de la centrale atomique de Fukushima-Daiichi,

http://www.lefigaro.fr/actualite-fr...pour-l-arret-de-la-centrale-de-fessenheim.php
La catastrophe nucléaire de Fukushima pourrait faire une victime collatérale en Alsace: Fessenheim. La centrale la plus vieille de France, mise en service en 1977, suscite en effet de nombreuses inquiétudes.

http://japan.failedrobot.com/
This map visualises crowd-sourced radiation geiger counter readings from across Japan. Click on the circles to get more information on the source of each reading.

 

[AtomicWombat]

You are a new poster here and i understand you haven't gone over the thousands of posts. All the things you mention were discussed here a while ago and debunked basically.
Reactor 3: The big blast is not directly related to the destruction of the top parts of the reactor, there were images posted here that show it's still there, with a crane collapsed over it, and steam escaping from the connection chute between that and the SFP. Also notice that the truss structure over the containment is intact unlike over the SFP. The thermal imagery, somehow surprisingly paints a rather rosy picture, with nothing substantially warm. A lot of seemingly hot spots arise from changes in the range of the IR measurements, with debris lying around at essentially ambient temperature. There are hot spots (70degC) over the SFP and the leaking parts from the PCV but that's about it, the rest are more or less cooler than a human being (less than 36degC), if a person was there it would be glowing red.

I've been with this discussion pretty much since the start and the possibility of the No.3 explosion originating in the primary containment and blowing off the containment plug has NOT been debunked; it has been debated with no clear consensus so far.

I don't believe this occurred. At the time of the explosion TEPCO was pumping in water using a fire engine. You don't overpressure a massive pressure vessel and not have a nylon fire hose still attached to the feed line not burst. If the RPV over-pressurized then every pipe, fitting, connection to the reactor with a lower pressure rating would have gone first, followed by the RPV assuming it didn't depressurize fast enough.

The RPV is approximately 6 inches thick. The pressures required to yield a 6 inch thick piece of steel even at elevated temperatures is huge. I understand the reactor has an operating pressure, but the failure pressure is much higher.

The failure mode of an over pressurized reactor with a corium slag at the bottom would be to fail the bottom of the RPV. This is the same failure mode you see when a water heater fails. It looks like this..



If that occurred with the reactor we'd be looking at the reactor vessel sitting somewhere outside of the building.

This is why you design the system to fail anywhere but the RPV.

I'm not going to dig up the maths again but under reasonable assumptions the explosion that destroyed building 3 had enough overpressure to exceed the RPV operating prerssure by 2-3 times.

Corium melt dropping into the drywell is NOT the same failure mode as a water heater. The steam and Zr-H2o explosion would cause a pressure rise outside the RPV and the explosion could bypass the RPV, which does not fully occlude the primary containment.

The mechanism of the building 3 explosion remains open, but any explanation MUST explain why it is clearly different from the explosion in builkding 1.

 

[AntonL]

Is there any "reasonable" estimate as to when sufficient cooling of the core(s) might be expected to occur and thus eliminate the need for continued high volume water cooling and permit consideration of some type of permanent containment of the core material?

Assuming reactor 2 was working at design capacity of 2380MW thermal at shutdown, I plotted the decay in heat in Watt against days from shutdown and also showed the amount a water at 25^oC needed to boil this away to keep the core at constant temperature. As you can see without secondary cooling it is a very long time before before it cools. That s why the spent fuel is kept upstairs for such a long time - it is just too hot to move safely.

Bottom line, secondary cooling needs to be installed and with the contamination and flooding in the basement I put in question if existing secondary cooling will ever function again, It may be better to use the basement as a water store and build new secondary cooling above ground level. The possibility to re-inject the contaminated water should also be considered as the amount of waste water can be reduced.

[PLAIN]http://k.min.us/ikojis.jpg

[PLAIN]http://k.min.us/ikop60.JPG

Edit: Thanks to tsutsuji san a small correction in the text

 

[PietKuip]

about alpha and beta particle detections... listen to the 4:18 - 4:30 intervall


What does he means?

I have no idea, but I looked at the beta data from San Francisco. It is difficult to see longer time series, but the count rates seem a bit higher than usual - see attachment.

 

[AntonL]

@Krikkosnack and PietKuip

Alpha radiation - positive charged helium nucleus traveling at high speed
Beta Radiation - negative charged electron traveling at high speed
Gamma Radiation - electromagnetic waves

http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html

 

[sp2]

available in english as well: http://www.nisa.meti.go.jp/english/files/en20110412-4.pdf

another question:
tepco is concerned, that the radiation may reach the chernobyl values.
http://english.kyodonews.jp/news/2011/04/84828.html

as the radiation currently leaks much slower than before, this would mean, that they expect/fear that the current situation lasts *for years* ?

Or, as I speculated last night, before my post was deleted, could it mean that they expect the release rate to get much worse again sometime soon?

 

[Samy24]

Normaly strontium should not travel that far. There was not heavy graphite fire like in Chernobyl. If strontium could travel that far, that would also be possible for plutonium.

http://english.kyodonews.jp/news/2011/04/85002.html"

 

[TCups]

I've been with this discussion pretty much since the start and the possibility of the No.3 explosion originating in the primary containment and blowing off the containment plug has NOT been debunked; it has been debated with no clear consensus so far.

The mechanism of the building 3 explosion remains open, but any explanation MUST explain why it is clearly different from the explosion in builkding 1.

Yes, what the Wombat said above, but with a few added comments:

1) it was not a single explosion at unit 3 -- there were multiple explosions, probably 3 discrete explosive events.

2) it appears that there may have been simultaneous or near simultaneous explosions involving:
a) the "containment" - exact nature and extent of damage unknown,
b) the spent fuel pool - with partial ejection of the contents of the SFP, extent unknown, and
c) an explosion of accumulated hydrogen with destruction of the building (secondary containment)

. . . and with a bunch of added questions:

As for the definition of "cold" in regards to the residual core temperatures, how cold is cold enough to add boron (or some other material?) to prevent re-criticality and to consider entombing the residual core contents in concrete without ongoing cooling? It it a matter of weeks, months or years that might be anticipated to achieve this?

It is in the realm of possibility to consider entombment combined with a closed loop cooling system? I can't see how.

Would spent fuel be entombed as well (seems doubtful)? If not, then would not some sort of clean up of the spent fuel would have to precede permanent entombment?

What of the "giant elephant" in this disaster scenario, the little mentioned large SFP7 out back? The spent fuel stored there will have to be permanently maintained somehow. This will either have to occur in place or all of that spent fuel is going to have to be removed and stored at an alternate facility that is not highly contaminated and dangerous on a long term to maintain.

What does the "big picture" TO DO LIST look like for Fukushima? Perhaps:

1) cool the cores of U1, 2, 3,
2) contain, entomb the cores of U1, 2, 3,
3) clean up SFP1, 2, 3, 4,
4) clean up external contamination near and far from the Fukushima site as best possible,
5) safely operate or permanently shut down U5,6, and
6) safely operate or permanently shut down SFP7,

So far, it seems to me that TEPCO is still struggling with item #1, and perhaps starting on item #4.

Am I missing any of the "BIG" items on the to do list?

Addendum:
Here's one I may have missed:
7) build a giant new facility for the long-term storage, reprocessing, and disposal of high-level radioactive wastes. Somewhere within a 20K radius of the Fukushima plant might seem an obvious location, given real estate prices.

 

[tsutsuji]

I just found this :

Fact Sheet : Major Modifications and Upgrades to U.S. Boiling Water Reactors With Mark I Containment Systems

1. Added spare diesel generator and portable water pump — 2002.
2. Added containment vent — 1992.
3. More batteries in event of station blackout — 1988.
4. Strengthened torus — 1980.
5. Control room reconfiguration — 1980.
6. Back-up safety systems separated — 1979

http://resources.nei.org/documents/japan/major_mod_usbwr_4511.pdf

"updated 4/1/11" according to http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/reactor-designs/

Note that the caption on the picture reads "portable pump & diesel", implying the diesel is "portable" too, and shown on a vehicle with wheels.

 

[NUCENG]

Normaly strontium should not travel that far. There was not heavy graphite fire like in Chernobyl. If strontium could travel that far, that would also be possible for plutonium.

http://english.kyodonews.jp/news/2011/04/85002.html"

Strontium Sr is even more reactive with water than calcium. It can be transported in water or in droplets with vapor. So it may be much easier to transport than plutonium which tends to form oxides.

Sr-90 uptake in plants and concentration in milk are its method of entering the body. Once there it concentrates in bones and is reputed to cause bone cancers and leukemia.

Also there is a much higher fission yield of Sr and its predecessors (Kr and Rb) than generation of Pu.

 

[Astronuc]

Normaly strontium should not travel that far. There was not heavy graphite fire like in Chernobyl. If strontium could travel that far, that would also be possible for plutonium.

http://english.kyodonews.jp/news/2011/04/85002.html"

I would expect those in the water being discharged in the ocean.

The measurements are mostly for volatiles such as Cs and I isotopes, which easily get out. Cs is also a decay product of Xe, which makes it easier to transport. On the other hand, Xe-137 has a very short half-life.

I would expect any fuel particles to be local to the plant, and discharge water.

Any failure from the spent fuel pool might pose a risk of release of less volatile fission products, if temperatures were high enough.

I'd be looking for Np-239 in the water, as well as isotopes of Eu, Ce, Ba, La, Y, Zr.

 

[AntonL]

once upon a time man learned to master fire
something no other living creature done before him
man conquered the entire world

one day he found a new fire
a fire so powerful it could never be extinguished
man reveled in the thought
that he now possessed the power of the universe

then in horror he realized
that his new fire could not only create but could also destroy
not only could it burn on land but inside all living creatures
but inside his children the animals and all crops

man looked around for help but found none
and so he build a burial chamber deep in the bowls of the earth
a hiding place for the fire to burn into eternity
when the burial chamber was complete
man laid his new fire to rest and tried to forget about it

he knew only through oblivion would he be free of it
but then he started to worry
that his children might find the burial chamber
and awake the fire from its sleep

so he begged his children
to tell their children and their children's children too
to remember forever to consign the burial chamber to oblivion
to remember forever to forget

extracted from
a 71 minute film documenting "Onkalo"
Finland's world’s first permanent repository for nuclear waste
that must last 100,000 years as this is how long the waste remains hazardous.

 

[Samy24]

Strontium Sr is even more reactive with water than calcium. It can be transported in water or in droplets with vapor. So it may be much easier to transport than plutonium which tends to form oxides.

Sr-90 uptake in plants and concentration in milk are its method of entering the body. Once there it concentrates in bones and is reputed to cause bone cancers and leukemia.

Also there is a much higher fission yield of Sr and its predecessors (Kr and Rb) than generation of Pu.

I was a child at the time of the Chernobyl desaster and we learnd that only a small amount (<3%) of the Strontium in the reactor was released and most landed in the direct perimeter of the plant.

Cs-137 and Sr-90 have nearly the same physical half-life but the biological half-life in human body of Cs is only about 110 days. In comparision to Sr it is about 18 years.

If Sr can be transported with steam, and steam is coming out of the plant till today this could be a bad thing for the long term in that region.

 

[NUCENG]

I was a child at the time of the Chernobyl desaster and we learnd that only a small amount (<3%) of the Strontium in the reactor was released and most landed in the direct perimeter of the plant.

Cs-137 and Sr-90 have nearly the same physical half-life but the biological half-life in human body of Cs is only about 110 days. In comparision to Sr it is about 18 years.

If Sr can be transported with steam, and steam is coming out of the plant till today this could be a bad thing for the long term in that region.

I agree, and I also wish the regulators and TEPCO were reporting more of the isotopes in air, water and on land. Even if it only is a report that the other isotopes aren't there. We may end up having to wait for this information until they stabilize the site. In the meantime they are creating an exclusion zone and restricting agriculture which may be the way they are trying to be safe. And unless they can stabilize the plants this will only get worse. From that viewpoint their priorities are reasonable.

 

[Samy24]

I would expect those in the water being discharged in the ocean.

The measurements are mostly for volatiles such as Cs and I isotopes, which easily get out. Cs is also a decay product of Xe, which makes it easier to transport. On the other hand, Xe-137 has a very short half-life.

I would expect any fuel particles to be local to the plant, and discharge water.

Any failure from the spent fuel pool might pose a risk of release of less volatile fission products, if temperatures were high enough.

I'd be looking for Np-239 in the water, as well as isotopes of Eu, Ce, Ba, La, Y, Zr.

The fuel pool thing looks like a good direction. TEPCO is on the same way now!

TEPCO, meanwhile, took 400 milliliters of water from the spent fuel pool of the No. 4 unit to check to what extent the spent nuclear fuel stored there is damaged.

There is a possibility that the fuel may have been temporarily exposed when the water level at the storage pool dropped following the March 11 disaster, but camera footage found that the water level now was enough to cover the fuel. But the temperature of the water was 90 degrees, much higher than the usual 20-30 degrees.

http://english.kyodonews.jp/news/2011/04/85030.html"

 

[tsutsuji]

Professor Magdi Ragheb provides the following analysis :

Figure 15. Plant layout of the Advanced Boiling Water Reactor generator, ABWR, identifies the diesel generator (18) as clearly high up at the level of loading deck inside the reactor building (upper left), and could not have been flooded by the tsunami. The transformers in the switchyard. (33), which were misidentified from satellite photographs as the diesel generators, are outside the building enclosure and could have been affected by the tsunami. The real vulnerability from the tsunami is the flooding of the lower level of the plant that would have impacted the functioning of the electrical components as well as the Residual Heat Removal, RHR pump (15), the HPCF pump (16), and most importantly, the Reactor Core Isolation Cooling RCIC system steam turbine and pump (17). The same vulnerability could be identified as an accident initiating event fro reactors sited at interior locations vulnerable to floods occurrence. Source: GE.

page 11/55 of https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Fukushima%20Earthquake%20and%20Tsunami%20Station%20Blackout%20Accident.pdf (dated 4/11/2011)

Put together with http://www.asahi.com/english/TKY201104060126.html , Mr Ragheb's figure is probably a closer description for Fukushima Daini (No 2), where the diesel are inside the reactor building, rather than for Fukushima Daiichi (No 1), although none of them are ABWRs.

 

[Astronuc]

The fuel pool thing looks like a good direction. TEPCO is on the same way now!

TEPCO, meanwhile, took 400 milliliters of water from the spent fuel pool of the No. 4 unit to check to what extent the spent nuclear fuel stored there is damaged.


http://english.kyodonews.jp/news/2011/04/85030.html"

If the water is warm, then the cooling is not adequate.

If they took samples of the water, I wish they would also take video of the SFP, or at least the tops of the fuel assemblies. I would then be relatively easy to judge the condition of the fuel. The upper tie plates should be visible near the top of the racks. If not, then can assume the fuel rods are broken. Of course, the fuel rods could be breached. Then one would look for discolourations, or other abnormalities. They will need some special hooded/sipping fuel handling systems to hand the fuel.

 

[Jorge Stolfi]

Updated my plots of #Fukushima reactor #1-#3 vars (temp,pressure,water level,CAMS) up to NISA release 89 (apr/12 13:00) #
http://bit.ly/gAuxse

 

[Jorge Stolfi]

Here's one I may have missed:
7) build a giant new facility for the long-term storage, reprocessing, and disposal of high-level radioactive wastes. Somewhere within a 20K radius of the Fukushima plant might seem an obvious location, given real estate prices.

TEPCO was building such a facility: www.nirs.org/reactorwatch/accidents/6-1_powerpoint.pdf

 

[Samy24]

Updated my plots of #Fukushima reactor #1-#3 vars (temp,pressure,water level,CAMS) up to NISA release 89 (apr/12 13:00) #
http://bit.ly/gAuxse

Why there is no update for unit 1 and 2? They repeated the data from the report 88. Someone can speculate they want to hide something :)

http://www.meti.go.jp/press/2011/04/20110412006/20110412006-3.pdf"
http://www.meti.go.jp/press/2011/04/20110412002/20110412002-3.pdf"

 

[Jorge Stolfi]

Naive question: if a critical mass of fissile fuel is spread it out evenly in three dimensions, does it continue to be critical?

 

[Astronuc]

Naive question: if a critical mass of fissile fuel is spread it out evenly in three dimensions, does it continue to be critical?

Criticality has to much to do with composition (fissile material, fuel matrix, moderator, burnable poisons (e.g., boron, gadolinia, . . .)), concentration (of each element species) and geometry (fuel lattice as well as size/array of fuel materials). Usually, if a system is critical, then the material is increased in volume, the critical system becomes subcritical, because the concentration decreases, particularly if the material mass is fixed, but the volume increase, and the surface area increases. Larger surface area means more leakage of neutrons from the system.

 

[AntonL]

TEPCO was building such a facility: www.nirs.org/reactorwatch/accidents/6-1_powerpoint.pdf

That is a fuel reprocessing facility

What is needed a nuclear waste processing facility, they have such a facility on site south of Unit 4, but that would be only for lightly contaminated waste

 

[Samy24]

Criticality has to much to do with composition (fissile material, fuel matrix, moderator, burnable poisons (e.g., boron, gadolinia, . . .)), concentration (of each element species) and geometry (fuel lattice as well as size/array of fuel materials). Usually, if a system is critical, then the material is increased in volume, the critical system becomes subcritical, because the concentration decreases, particularly if the material mass is fixed, but the volume increase, and the surface area increases. Larger surface area means more leakage of neutrons from the system.

Good to hear it is save by design. The other way it would be the bigest known atomic bomb.

 

[PietKuip]

Updated my plots of #Fukushima reactor #1-#3 vars (temp,pressure,water level,CAMS) up to NISA release 89 (apr/12 13:00) #
http://bit.ly/gAuxse

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/plot-un1-full.png

Core pressure of Unit 1 steadily rising.

Is that getting dangerous?

 

[Samy24]

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/plots/cur/plot-un1-full.png

Core pressure of Unit 1 steadily rising.

Is that getting dangerous?

I do not find the PDF doc at the moment but they have tested it at 7x the actual pressure and at that stage a valve would open automaticaly to release some pressure. I do not know if this thing is still working but there is much room there.

 

[clancy688]

Core pressure of Unit 1 steadily rising.

Is that getting dangerous?

I'd like to know that as well. And more questions:

- Unit 2 and 3 pressure seems to be around atmosphere level, containment / pressure vessel breach has so far been confirmed for unit 2 (as far as I know...) but what's with unit 3?

- at Unit 2 and 3 there's a fluctuation in water level right before the explosions, where's the connection between these two events?

- drywell radiation sensor in Unit 1 seems to be gone, after topping 100 Sv/h and then falling back at ~70. Is 100 Sv/h the maximum level it can measure? Was it fried by higher radiation levels? And is there any connection between this failure, higher drywell radiation and rising core pressure?

 

[AntonL]

Bottom line, secondary cooling needs to be installed and with the contamination and flooding in the basement I put in question if existing secondary cooling will ever function again, It may be better to use the basement as a water store and build new secondary cooling above ground level. The possibility to re-inject the contaminated water should also be considered as the amount of waste water can be reduced..

Not only is an external cooling being considered they also thinking of flooding the PCV
TEPCO also admit existing cooling is most probably in non functioning condition

so my earlier assessment was not all that wrong

Fukushima Daiichi Nuclear Power Station for TEPCO and the government is pulling the pipes leading to outside the reactor building began consideration of a new system to cool the reactor while circulating the water. Order to create conditions that fuel in the water, which also plans to submerge the emerging nuclear fuel to each cylinder submerged in the containment. Ease of operation due to damage to the reactor, and so each one is thinking of a different response.
...
　Not depend forever on irrigation. TEPCO aims to recover the conventional cooling system circulating water is not expected to stand at the moment. Is expected that the pipes and pumps were destroyed by the earthquake and tsunami. There is also an area that exceeds 10 Sv per hour at the bottom of the containment should also expect the repair work is 近Dzukezu workers is not easy.

[URL]http://www.asahi.com/science/update/0412/images/TKY201104120242.jpg[/URL]

 

[liamdavis]

I think you're mis-remembering, or someone gave you bad info in 1970. Standard Tech Specs call for seven days diesel fuel onsite. There may be more fuel, but it wouldn't be in seismic storage tanks, and it wouldn't be available to the emergency diesels without manually opening cross ties and possibly using non-safety related transfer pumps. And I really doubt the six month figure. That would be over 3/4 million gallons per diesel generator (taking a swag at 200 gph). I've never seen diesel fuel tanks that size at a nuclear unit.

You are right. We have one and two million gallon tanks at work for fire suppression water and the tank at Pilgrim 1 was not that size. I may have been remembering being told that the need for the generators and fuel was because it could require six months of cooling after the shutdown of an operating reactor.

The tank shown on Pg 9 of this document citing a 1979 TEPCO generator problem looks to be in the 30-40,000 gal range. https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Fukushima%20Earthquake%20and%20Tsunami%20Station%20Blackout%20Accident.pdf

 

[AntonL]

Strawberries, tomatoes and vegetables from the Fukushima district are not only tasty and full of vitamins - by the process of irradiation they are preserved and last longer without refrigeration. Yokio Edano and comedian Yamazaki Shizuyo (Shizu-chan)

(apologies - could not help cynical humour)

 

[liamdavis]

I wonder if we don't have translation issues here. The way I read that, it doesn't mean that cooling for the generators themselves was lost, but that the pumps that the diesels were to operate had nothing to pump. Perhaps the tsunami took out plumbing from the ocean or some heat exchange equipment. Diesels themselves require special coolant (SCA or OAT) to prevent internal damage (cavitation damage to cylinder sleeves, etc), sea water use would be extremely short term as a coolant in a diesel.

Perhaps translation is part of the problem. It seemed they were citing pump failure as the cause of the generator failure??

I know they also have more important things at hand than my need for information at the moment but they are as sparse with words as I am. Still, I prefer that they be accurate in their information than just provide me with volume of it.

It concerns me that the inability to approach many areas of the facilities will lessen the information available to reconstruct events in detail and lower the value of lessons learned. As bad as this is I want to see the maximum value of wisdom extracted from it.

To address your second point, "the pumps that the diesels were to operate had nothing to pump", if the sea water or reactor coolant pumps were disabled then it would not have helped to have offsite or emergency power. This incident would have occurred. We would have had a better picture of it progression.

 

[clancy688]

Strawberries, tomatoes and vegetables from the Fukushima district are not only tasty and full of vitamins - by the process of irradiation they are preserved and last longer without refrigeration. Yokio Edano and comedian Yamazaki Shizuyo (Shizu-chan)

Their smile looks really forced, doesn't it? And Edanos looks like he's thinking "Is he really going to swallow this tomatoe? I'm only going to eat my strawberry if he's eating his, too!" ;)

 

[elektrownik]

Their smile looks really forced, doesn't it? And Edanos looks like he's thinking "Is he really going to swallow this tomatoe? I'm only going to eat my strawberry if he's eating his, too!" ;)

Taste like Chernobyl... ;)

 

[Giordano]

I'm trying to learn more about bioaccumulation, which is a new concept for me. Does anyone have some link to some credible material with concentration factors of for example Cs-137 in fish?

I have of course tried to search myself... with little success.

 

[bytepirate]

If the water is warm, then the cooling is not adequate.

If they took samples of the water, I wish they would also take video of the SFP, or at least the tops of the fuel assemblies. I would then be relatively easy to judge the condition of the fuel. The upper tie plates should be visible near the top of the racks. If not, then can assume the fuel rods are broken. Of course, the fuel rods could be breached. Then one would look for discolourations, or other abnormalities. They will need some special hooded/sipping fuel handling systems to hand the fuel.

is there any explanation for the explosion and the fires in #4, that works *without* massive fuel damage?
in this document: http://www.vgb.org/vgbmultimedia/News/Fukushimav15VGB.pdf the core damage of #1 is estimated to 60-80%, derived from the production of hydrogen necessary to blow away the top of the building.
#4 looks even worse...
in the same document, the time for dry-out of #4 SFP is estimated 10 days. the explosion was much earlier.
if that explosion was a hydrogen explosion (what else?), then it should be a save assumption, that the pool has a leak.
if the pool has a leak, then every new (even small) quake could make it larger.
if it is possible to get the fuel out there, i would put all my efforts in it, if i were tepco.

i would really appreciate a rebuttal of my 'analysis'.

 

[bytepirate]

I'm trying to learn more about bioaccumulation, which is a new concept for me. Does anyone have some link to some credible material with concentration factors of for example Cs-137 in fish?

I have of course tried to search myself... with little success.

http://www.dec.state.ak.us/air/am/rad/doc/RN4.pdf

 

[Jorge Stolfi]

Usually, if a system is critical, then the material is increased in volume, the critical system becomes subcritical, because the concentration decreases, particularly if the material mass is fixed, but the volume increase, and the surface area increases. Larger surface area means more leakage of neutrons from the system.

Yes, of course. Sorry. (That is what I always knew, but yesterday I wrongly concluded that density should not matter, only mass and shape. I had ignored the fact that the cross-section of nuclei remains constant as the volume is increased.)

 

[Giordano]

http://www.dec.state.ak.us/air/am/rad/doc/RN4.pdf

Thanks!

The concentration factor of Cs-137 in fish is stated as approx 100.

 

[ceebs]

Strawberries, tomatoes and vegetables from the Fukushima district are not only tasty and full of vitamins - by the process of irradiation they are preserved and last longer without refrigeration. Yokio Edano and comedian Yamazaki Shizuyo (Shizu-chan)

(apologies - could not help cynical humour)

I see that and can only be reminded of this

http://news.bbc.co.uk/1/hi/uk/369625.stm"

Probably the most derided politician to emerge out of the BSE scandal, John Gummer will always be remembered for making great public show of feeding his four-year-old daughter Cordelia a hamburger in the midst of the "mad cow" disease scare.

The press photographed Mr Gummer - then Agriculture Minister in the Conservative government - tucking into the burger with his little girl at a boat show in Suffolk on May 6 1990.

 

[Jorge Stolfi]

in the same document, the time for dry-out of #4 SFP is estimated 10 days. the explosion was much earlier.
if that explosion was a hydrogen explosion (what else?), then it should be a save assumption, that the pool has a leak.

The 3/11 earthquake included several minutes of large slow motion. Someone previously suggested that some of the water in the pool may have sloshed out (perhaps down the spent-fuel chute?)

The spent-fuel pools were "re-racked" recently to increase capacity. What does that mean? Perhaps stacking fuel in 2 layers (leaving only 5-6 meters of water above fuel instead of original 10 m?)

Hydrogen generation ins substantial quantities seem to require temperatures over 800C. At 660C or less, the neutron absorbing baffles in the pools melt or disintegrate.

 

[Cire]

I'm not going to dig up the maths again but under reasonable assumptions the explosion that destroyed building 3 had enough overpressure to exceed the RPV operating prerssure by 2-3 times.

Failure pressure and operating pressure are two completely different things. 10x operating pressure would not fail the RPV. It would fail the support plumbing and interconnects but not the pressure vessel.

For example, the Trieste, the deepest diving vessel ever made had a 5" thick steel pressure vessel. It was "rated" for 110MPA! That's ~16,000 PSI. That's the rated pressure, not the failure pressure. The RPV's in the plant are over an inch thicker then this example.

In no way did the hydrogen explosion overpressure the reactor vessel, or for that matter the steam pressure inside overpressure the vessel.

Corium melt dropping into the drywell is NOT the same failure mode as a water heater. The steam and Zr-H2o explosion would cause a pressure rise outside the RPV and the explosion could bypass the RPV, which does not fully occlude the primary containment.

If corium breached the bottom of a pressurized vessel the water vapor and gasses and whatever else wanted too would be ejected at near supersonic velocities producing a massive impulse on the RPV. If the RPV had no water or vapor and was depressurized when the melt occurred, then that would be a very different scenario. I haven't seen anyone argue the RPV was dry and unpressurized.

 

[sigyn]

Re: Comparison of Trieste and RPV, wall thickness: Does this not require the dimension of the vessel ? a 10 meter vessel will require thicker walls than a 1 meter vessel ?