Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[rhody]

http://www.guardian.co.uk/world/2011/mar/29/japan-nuclear-plant-us-robots"

Finally, I am glad to see our president turn his attention from Libya to the crisis in Japan...

The Obama administration is sending a squad of robots to Japan to help efforts to regain control over the Fukushima nuclear plant, it has emerged.

"A shipment is being readied," Peter Lyons, who oversees nuclear power in the department of energy, told a Senate committee. "The government of Japan is very, very interested in the capabilities that could be brought to bear from this country."

The news came as the Japanese government said it was considering nationalising the operator of the crippled power plant at the centre of the worst nuclear accident in the country's history, amid mounting criticism of its handling of the crisis.

"Our preparedness was not sufficient," government spokesman Yukio Edano said. He said that when the current crisis was over they would examine the accident closely and thoroughly review safety standards

and

Robots, with electronics built to withstand radiation, can work in areas of Fukushima where radiation levels would soon kill a human engineer.

They can also help experts get a view on damage to the reactor core. Lyons said the robots would be equipped with cameras as well as devices to measure radiation.

"They could go places where you certainly wouldn't send a person," he said.

The department of energy has developed a number of remotely operated robots designed to clear up radioactive waste from department of energy test weapons sites, Lyons said.

The earliest versions were developed in the wake of the Three Mile Island accident in 1979 when robots were sent into get a view of the damaged reactor, and to suck up radioactive water and partially melted fuel.

Rhody...

P.S. Perhaps someone in the adminstration woke up and picked up on one of my earlier posts (I wish, lol) Astronuc, is there a possiblility you could go too to add your expertise with fuel analysis ?

https://www.physicsforums.com/showpost.php?p=3217241&postcount=1910"

http://www.washingtontimes.com/news/2011/mar/24/fears-rise-that-japan-could-sell-off-us-debt/"

 

[razzz]

From http://www.spiegel.de/international/zeitgeist/0,1518,709345,00.html"

"...In the regions where it is particularly problematic, all boar that are shot are checked for radiation," reports Andreas Leppmann, from the German Hunting Federation. There are 70 measuring stations in Bavaria alone.

In addition, for the last year and a half, Bavarian hunters have been testing ways to reduce the amount of caesium-137 absorbed by wild boar. A chemical mixture known as Giese salt, when ingested, has been shown to accelerate the excretion of the radioactive substance. Giese salt, also known as AFCF, is a caesium binder and has been used successfully to reduce radiation in farm animals after Chernobyl. According to Joachim Reddemann, an expert on radioactivity in wild boar with the Bavarian Hunting Federation, a pilot program in Bavaria that started a year and a half ago has managed to significantly reduce the number of contaminated animals..."

I see some very sterile 1,2,3 scenarios here. Literally in the dark with no power hence no coolant circulation and continuous venting of pressures leading to hydrogen explosions and workers evacuated due to 'events' and the company suggests 70% damage to rods in unit 1 core, it is safe to assume there is at least one radioactive debris pile. After any hydrogen blast how do you account for shock-wave travel and effect esp. internally? A 'leaky loop' just begins to sum things up.

 

[jinxdone]

@NUCENG

that's all, i hope

let's go ahead

Here's one more image for good measure, taken on the overflight on march 17th. The vertical section looks to be of a different color for some reason.

 

[TCups]

Hey pipe guys -- I thought so earlier and seem more convinced now. Those pipes are segments bolted together at flanges. Depending on the time of day, a shadow cast from the flange could make the photos look different. Ditto for any dirt or debris that might accumulate on one side or the other of the flange.

 

[M. Bachmeier]

Got a question about basic maintenance re: shutdown with rods removed.

Is the empty reactor core flushed with solutions (acidic, alkaline etc.) to eliminate any possible contaminants before refueling?

 

[Astronuc]

Got a question about basic maintenance re: shutdown with rods removed.

Is the empty reactor core flushed with solutions (acidic, alkaline etc.) to eliminate any possible contaminants before refueling?

It depends on the water chemistry. They can shock the system, e.g., with peroxide, and let the crud burst. The water is then filtered in the Reactor Water CleanUp (RWCU) system. This happens while the plant cools down. When the head is removed and the cavity open, there is a cooling system running.

With a lot of failed fuel, that is a big problem. Failed fuel can 'burp' fission gases. With core damage, it's not clear yet how the would retrieve the fuel, other than with a specially developed ROV system.

 

[PietKuip]

30 Sv per hour sounds very frightening, almost as if there was a small fission process taking place somewhere in that pool of water. Since that is unrealistic, the measurements must be off, someway or somehow.

The frightening thing is that Tepco only says "> 1000 mSv/h". What is wrong with those people?

 

[M. Bachmeier]

It depends on the water chemistry. They can shock the system, e.g., with peroxide, and let the crud burst. The water is then filtered in the Reactor Water CleanUp (RWCU) system. This happens while the plant cools down. When the head is removed and the cavity open, there is a cooling system running.

With a lot of failed fuel, that is a big problem. Failed fuel can 'burp' fission gases. With core damage, it's not clear yet how the would retrieve the fuel, other than with a specially developed ROV system.

I was thinking more about unit #4, wondering if a solution could have been in the core at the time of the quake? And, if so, would the solution (if leaked back into SFP through failed gate seal) contribute to more rapid heating by dissolving or weakening the cladding on the spent fuel rods?

 

[jensjakob]

The frightening thing is that Tepco only says "> 1000 mSv/h". What is wrong with those people?

My assumption is that 1000 mSv/h is somehow related to Article 10 or 15 in this document:
http://www.nisa.meti.go.jp/english/resources/legislativeframework/files/EmergencyPreparedness.pdf

i.e. it is a limit stated by the the "cabinet order" that Tepco must report when they cross.

So my theory is that TEPCO is obliged to report that they have crossed the limit, but TEPCO isn't obliged to report by how much.

Remember - we're talking gigantic liabilities here, and corporate damage control is working in high gear - propably some of the best paid lawyers in TEPCO are managing the crisis-information (who wouldn't do that...)

 

[RealWing]

It depends on the water chemistry. They can shock the system, e.g., with peroxide, and let the crud burst. The water is then filtered in the Reactor Water CleanUp (RWCU) system. This happens while the plant cools down. When the head is removed and the cavity open, there is a cooling system running.

With a lot of failed fuel, that is a big problem. Failed fuel can 'burp' fission gases. With core damage, it's not clear yet how the would retrieve the fuel, other than with a specially developed ROV system.

At TMI they used long handled tools to load broken fuel elements etc into cannisters. They had to use boring machines to break up the solidified mass. Underwater plazma cutters were used to cut up vessel internals. Took them 4 years to "defuel" the core.

 

[jensjakob]

Even though it is a BWR6 reactor, this guide can provide hints to many answers on FUkushima configuration:
http://www4.ncsu.edu/~doster/NE405/Manuals/BWR6GeneralDescription.pdf

 

[|Fred]

2. A reactor pressure vessel is a massive heat sink. I believe the drywell on both reactor 1 and 2 where flooded early on in the process; providing addition temperature relief. This doesn't include the water that has been injected since the start of the accident..

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper written by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

E.g. to receive a dose of 1 mSv in 50 years it requires about ingestion of about 80000 Bequerel of Caesium 137 but only about inhalation of 15 Bq of Plutonium. The activity in Bq in the environment is relatively simple to determine.

I think this statement is wrong there is a 20 factor ponderation between alpha and beta, please correct me a dose of 1mSv it would require contact with a 10 000 Bq source of 137Cs or a 500 Bq source of Pu

 

[Bodge]

So, is it currently feasible for there to be a large steam explosion in (under) any of reactors 1-3?

Could there be corium in an unbreached RPV, suspended above a saturated area?

 

[Bodge]

I'm looking at Reactor 1 in particular.

But, in any reactor, could the conditions above still conceivably develop in the next few days?

 

[Astronuc]

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper written by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

A contact at GE indicate that flooding containment is standard op in the case of a LOCA.

I would expect that TEPCO flooded containments on Units 1, 2 and 3 - in addition to getting water into the pressure vessel in order to reflood the core as much as possible.

 

[Cire]

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper written by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..

Here is a 1995 Paper by ECN on the IAEA website about flooding the drywell.. It's a good read.http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/27/036/27036479.pdf"


Quoted from the abstract:

In case of a severe reactor accident inside a Nuclear Power Plant (NPP), the
worst case scenario includes melt-down of a significant part of the core.
Without any counter measures, this will lead to failure of the Reactor
Pressure Vessel (RPV). In order to prevent failure of the RPV, the decay heat
generated by the corium pool has to be removed from the vessel at such rates
that excessive temperature rise of the vessel wall is averted.
Recently, flooding of the lower drywell or external (ex-vessel) flooding has
been suggested as a possible accident management strategy, with the purpose
to cool the relocated heat generating corium pool in such a way that vessel
failure is prevented.

My understanding is you flood the dry well by activating the fire suppression system in that area and not turning it off until you flood the area. I'm looking for the source material I read that stated the dry well was flooded. When I find it I'll be sure to link to it.

 

[Astronuc]

I was thinking more about unit #4, wondering if a solution could have been in the core at the time of the quake? And, if so, would the solution (if leaked back into SFP through failed gate seal) contribute to more rapid heating by dissolving or weakening the cladding on the spent fuel rods?

In a BWR, there would be no solution in SFP water or the reactor cavity. It's flooded with clean water, which is cooled and filtered.

I would expect that the gate was open, but I don't know as I'm not familiar with their procedures. Unit 4 was shutdown since Nov 30, 2010, and for whatever reasons, they do exceptionally long maintenance outages. The core had been cooling for 101 days at the time of the quake. The thermal burden should have been about 2.75 MW.

Most US plants try to minimize outage length. Some utilities have it down to about 15-17 days every 18 mo or 24 mo depending on the unit, although many units probably do it more like 20-30 days.

The earthquake certainly could have caused a structural failure somewhere in the pool or containment structure.

Some of the Kashiwazaki-Kariwa units sustained damaged from the Niigata earthquake, and Chubu's Hamaoka Units 1 & 2 were shutdown and decommissioned prior to the Suruga Bay earthquake of Aug 11, 2009.

 

[AtomicWombat]

An other question, I've heard this sentence: "because Plutonium is so dense and heavy, IT CANNOT go very far and be transported to a great distance from its source point, so it should stay around the vicinity of the plant".

I know it's a very dense element, but is this sentence 100% true?

Plutonium oxide is insoluble in almost everything, so it won't get into the food or water supply.

Plutonium (in its oxide form) is most dangerous when it is in fine particles of airborne dust. I see it as a little like asbestos. If in some accident a large amount of asbestos dust was to spread over an inhabited area, there would be a long term expectation of elevated rates of mesothelioma. The mechanisms and resulting cancers are different with plutonium (lung & bone cancers and leukemia) but it's that form of risk.

http://www.nvmp.org/pluto4.htm"

"If somebody inhales plutonium dust, he won't notice anything special. Only 10 to 50 years later is it possible that lung and bone cancer may develop. "

"Plutonium is not dangerous outside the body."

"...during fires in the US nuclear weapons complex Rocky Flats near Denver in 1957 and 1969 clouds of smoke containing plutonium dust spread over the town. However, the expected "epidemic" of lung cancer and congenital defects did not occur. Probably the plutonium dust did not reach the population because it came down quickly and became firmly adhered to the soil. Besides, extra cases of cancer or birth-defects in babies are difficult to distinguish from what people acquire "naturally". "

"Atmospheric testing between 1945 and 1963 brought 4.2 tons of plutonium dust directly into the environment. ... In theory 7,900 cases of cancer may have been caused by this plutonium. "

"Plutonium can go off when it is piled up, a 'criticality' disaster. ... The smoke coming out of the burning pile may lodge tiny particles containing plutonium deep in the lungs. Fall-out from an explosion of an atomic bomb also contains plutonium dust, and so does the smoke of a nuclear disaster like 'Chernobyl' and 'Windscale' "

 

[Astronuc]

About 15 years ago, I met one to two guys who experienced glove box explosions while working with Pu. The accidents has happened in the 70's, and he was still doing well in the 90's. He had had glass and Pu solution embedded in his face, neck and chest. As far as I know he's still alive, but I'll have to check.

 

[rhody]

About 15 years ago, I met one to two guys who experienced glove box explosions while working with Pu. The accidents has happened in the 70's, and he was still doing well in the 90's. He had had glass and Pu solution embedded in his face, neck and chest. As far as I know he's still alive, but I'll have to check.

Astronuc,

If someone suspects they have inhaled plutonium, are there medical or radiological tests to confirm it ?

Rhody...

 

[AtomicWombat]

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l58VoLI&feature=player_detailpage

 

[rhody]

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l58VoLI&feature=player_detailpage

AW,

He stirs the masses and at the same time putting himself front and center... Wait, did I just say that ! Doesn't he have a new book out as well, Wait, did I say that too !

Rhody...

 

[Astronuc]

Michio Kaku trying to calm fears and reassure people:

http://www.youtube.com/watch?v=qdq4l58VoLI&feature=player_detailpage

If they abandon ship?! Free fall?!

Um - we don't do that.


Incidentally from JNES http://ompldr.org/vN3VhMQ

 

[AntonL]

KYODO 11:04 30 March
NEWS ADVISORY: Radioactive iodine 3,355 times legal limit found in seawater near plant

So the trenches are overflowing

for the past detailed seawater analysis up to 28 march can be http://www.meti.go.jp/press/20110329013/20110329013-2.pdf"

and http://www.meti.go.jp/press/20110330002/20110330002-4.pdf" supporting the news advisory

and again Tc-99m 6 hour half life is detected - I hope measuring error

 

[ailog]

Any news on the fresh water that the US navy is/has barged to the site? Is it being put to use? I havn't seen anything about it recently.

 

[Astronuc]

From World Nuclear News:

A good description of the Fukushima event - http://www.world-nuclear.org/info/fukushima_accident_inf129.html

I've been wondering about the ground motion and accelerations. Apparently not all the data are collected and/or processed, but from WNN,

http://www.world-nuclear-news.org/RS_Fukushima_faced_14-metre_tsunami_2303113.html

More detailed data of the ground acceleration rates caused by the magnitude 9.0 earthquake have also been made available by Tepco. Although not all the data has yet been collected, they record very powerful tremors that exceed the design basis in one dimension.

At Daiichi there is still no data for units 1, 2 and 5, but available figures put the maximum acceleration as 507 gal from east to west at unit 3. The design basis for this was 441 gal. Other readings were below design basis, although east-west readings at unit 6 of 431 gal approached the design basis of 448 gal.

At the Daini plant, ground accelerations ranged from 186 gal in the vertical plane at unit 1 to 277 gal from north to south at unit 3, as recorded by sensors in the reactor building foundation. The range of design basis figures is a spread from 415 gal to 512 gal.

No mention of unit 4.

From - http://www.world-nuclear.org/info/inf18.html

Japan's Nuclear & Industrial Safety Agency eventually declared the accident as Level 5 on INES scale - an accident with wider consequences, the same level as Three Mile Island in 1979. The design basis acceleration for both Fukushima plants had been upgraded in 2008, and is now quoted at horizontal 441-489 Gal for Daiichi and 415-434 Gal for Daini. The recorded data for Daiichi are still being analysed, but it appears that 507 Gal was the maximum for it, and 251 Gal for Daini. (Ground acceleration was around 2000 Gal a few kilometres north, on sediments.)

 

[AntonL]

New idea - wrap the structures in special cloth to filter radio-activity

I suppose http://www.christojeanneclaude.net/wc.shtml" will be asked to help with the design - nobody more experienced.

From below info graphic:
But more important the highly radio-active water unit 2 to be shipped off-site - and then?

[URL]http://www.asahi.com/special/10005/images/TKY201103290521.jpg[/URL]

　Fukushima Daiichi nuclear power plant at TEPCO, 1,3,4 a rocket blew the building, Kan, the Cabinet is considering measures to prevent radioactive material dispersal of a special cloth to cover it. To ensure that working conditions for recovery and stable power supply to cool the reactors. Water pollution measures, including high levels of radioactivity leaking into the turbine building basement, is also out with a plan to collect contaminated water tankers. TEPCO has struggled to win work, they need to recognize more ambitious plans.

Yes a neat "out of the box idea" as an example of ambitious plan

 

[Reno Deano]

BWRs have an astounding number of penetrations (CRDMs and reactor instrumentation) coming through the bottom of the reactor vessel. A CRDM ejection is a remote possibility. But if the CRDM seismic supports failed, that could be the breach.

 

[razzz]

BWRs have an astounding number of penetrations (CRDMs and reactor instrumentation) coming through the bottom of the reactor vessel. A CRDM ejection is a remote possibility. But if the CRDM seismic supports failed, that could be the breach.

Apparently a 'leaky loop' is acceptable in this design since avenues are built-in. Maybe the graphite rod don't morph into rough diamonds due to heat but their seals sure can fail.

Too bad now that it is a problem just trying to keep the working environment safe. The contaminated cooling water or seawater is of secondary importance whether it discharged into the Pacific or tanker ship, as trying to keep the hot spots cool and keep the cool spots from becoming hot spot is of utmost importance. Even if they can keep the situation static, it's a waiting game.

I'd probably be unloading the (slightly) off site major spent fuel pond and then unload unit 5&6 ponds getting ready for the day that unit 4 pond can be unloaded...I don't even know if these things are possible.

 

[NUCENG]

Thank you Nuceng and Cire for those anwsers, you mention that the drywell (primary containment in concrete if I'm not mistaken) Has been flooded. I've seen this "idea" on the paper written by or for Areva.
But I haven't seen any statement , indications or explanation by the Japanese authorities or tepco that they did so ...
Is is a standard procedure ? how did they get some water there and when..


Early on TEPCO reports indicated that they were injecting seawater into the reactor pressure vessel. My Bad. I misremembered reading that they had been performing containment flood. However looking at the TEPCO updates since 11 March, I cannot confirm that. So my speculation of a steam explosion was invalid. However if melt-throu does occur, the interaction with containment concrete will be revealed by the activation and release of concrete materials.

I will do better job of checking my WAGs.