Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[PietKuip]

in this document (http://www.nisa.meti.go.jp/english/files/en20110327-1-5.pdf ) i understand there has been mistakes about I-134 and possibly other elements. But even without these I-134 and Co-56 numbers, something troubles me.

As i understand, they can only measure up to 1 sieverts with current equipment there (press reports worldwide are 1 sieverts per hour but original documents show MORE than 1 sievert per hour without more details. In this pdf, measurements inside Unit 3 are at 750 msv/h).

Knowing that for example :
I-131 - Unit 2 : 1.3×10E7 vs Unit 3 : 3.2×10E5
Cs-137 - Unit 2 : 2.3×10E6 vs Unit 3 : 5.6×10E4
the list goes on, but from what i see most elements are about 50 times higher in Unit 2 compared to Unit 3.

My question is : is there a way to calculate (approximately) the real number of Sv/h in Unit 2 (and outside Unit 2 probably now...), as we know Unit 3 water surface is at 750 msv/h ?

When the activity of the water is 50 times higher, the dose rate above the water is also 50 times higher, because it is the same brew of isotopes. Edit: assuming equal depth.

So yes, the dose rate in the turbine hall of unit 2 is about 30 sievert per hour.

Which makes it impossible to do work there.

 

[TCups]

When the activity of the water is 50 times higher, the dose rate above the water is also 50 times higher, because it is the same brew of isotopes.

So yes, the dose rate in the turbine hall of unit 2 is about 30 sievert per hour.

Which makes it impossible to do work there.

Activity in the contaminated water has been specified as sieverts per hour AT THE SURFACE. Would the absorbed dose be greater under the surface, as with a worker standing in the contaminated water?

 

[AntonL]

When the activity of the water is 50 times higher, the dose rate above the water is also 50 times higher, because it is the same brew of isotopes.

So yes, the dose rate in the turbine hall of unit 2 is about 30 sievert per hour.

Which makes it impossible to do work there.

Clever move to report >1000mSv , with 30Sv confirmed the exodus starts

Now considering the large area, what would the the radiation be say on the floor above?
or is 30cm to 40cm of concrete floor slab be sufficient shield?

 

[jlduh]

EDF announced a set of relief measures March 18, including the dispatch of experts and robots to the Fukushima plant in the wake of radiation leaks following a magnitude-9.0 earthquake and tsunami. But a media officer for Besson said the package is separate from TEPCO's request for support.

I want to mention that since the very beginning, TEPCO as refused any help from american experts, then refused the proposal of AREVA/EDF to send robots from France, and also refused help from IAEA (IAEA receives report from NISA which gets information from TEPCO as TEPCO is THE only source of information for what happens in the plant). Now it is confirmed that TEPCO is asking help from France.

These are facts. But they may lead to political conclusions... which i won't draw!

Pietkuip, you said:

When the activity of the water is 50 times higher, the dose rate above the water is also 50 times higher, because it is the same brew of isotopes.

So yes, the dose rate in the turbine hall of unit 2 is about 30 sievert per hour.

Ouchhhhhh...

thanks for the clarification!

But I see in many articles written that the radiation is 1 Sievert/h in turbine building 2, which i interpret then as a mistake from a misleading info if I understand well: is it that difficult to have instruments measuring more than 1 sievert/h? Again that's unbelievable so see how information is biased because of inaccuracies and again misleading infos from TEPCO... Saying it's "more than 1 Sievert/h" when it's probably 30 Sievert/h is a misleading way (as a minimum!) of saying things, don't you think?

 

[|Fred]

France, offered a week ago a few robots design to operate when men could not, Tepco or Japan , politely declined judging they were not necessary at the time. They likely reconsidered
(As far as we know Tepco did not refuse the 100t of boric acid, 3000 mask , 10 000 radiation suit, 20 000 Glove sent by Areva / EDF on the 17/18th)

 

[Astronuc]

That seems to be correct, steam coming from the transfer chute area, what are the implication for the containment - TCups that drawing of yours with orange flame marks seems very plausible.

As for the condition of the fuel in SFP with heavy stuff dropping in we can only speculate, An explosive shockwave followed by a crane falling into the pool, could that have "Tsunamied" a bundle of fuel rods out of the pool, that we speculated to have observed in other photos?


Below image of crane in block 4 for comparison, seems to gone missing in block 3
and for block 1 we can see in the video the roof wrapped around the crane

I believe the image is from - http://www.youtube.com/modchannel/?gl=JP&hl=ja
11-03-27 (March 27, 2011) 10:11:06 (video 2:32 / 4:21)

It seems similar to the screen shot I took.

I expect that the refueling or fuel handling machine is parked over or at the end of the spent fuel pool.

There is another shot of a yellow cap, which is probably the drywell head/cap of unit 4.

I would expect that the dry well cap is on the opposite end of the building from the spent fuel pool.

 

[TCups]

I believe the image is from - http://www.youtube.com/modchannel/?gl=JP&hl=ja
11-03-27 (March 27, 2011) 10:11:06 (video 2:32 / 4:21)

It seems similar to the screen shot I took.

I expect that the refueling or fuel handling machine is parked over or at the end of the spent fuel pool.

There is another shot of a yellow cap, which is probably the drywell head/cap of unit 4.

@Astronuc -
Yes. Just so we are on the same page --
The drywell cap and fuel handling machine in the screen shots you referenced are from unit 4, where,
1) the explosion appeared less intense than in unit 3, and
2) the fuel rods had been taken out of the reactor core 4 and put in the SFP 4
3) the fuel handling machine from unit 4 has been visible on all previous videos, I believe.

The annotated photo with the proposed location of the fuel handling machine actually in the SFP is from unit 3. The suggestion that the fuel handling machine is actually in the pool came from the reference in the initial post #1760
https://www.physicsforums.com/showpost.php?p=3215310&postcount=1760

To Recap
The venting steam is coming (or initially came) from unit 3, in an area where I suggest there may have been damage to the chute and gate forming part of the primary containment for RV3. I postulate that had the water level in SFP 3 been low, then there would have been no water behind the gate and that the loss of hydrostatic pressure behind the gate, plus possible compromise of the pneumatic seals of the gate, plus one hell of an explosion, may have damaged the primary containment at the location of the gate, whether the hydrogen explosion originated from within the drywall containment or from the top floor of the building.

The reinforced concrete weight bearing columns, east and west, coupled to the large rails for the overhead crane tended to hold the sidewalls together, such that the main force of the explosion (actually in both units 3 and 4) seem to have blown out the north-south walls and the roof.

In unit 3, the north wall weight bearing columns actually collapsed and the overhead crane ended up atop an adjacent building below on the north side of bldg 3.

 

[ivars]

http://saposjoint.net/Forum/viewtopic.php?f=66&t=2657&p=31438#p31438"

 

[Borek]

We discussed a view days back about international teams working hard to help solve this problem.

Only today it is confirmed that Tepco is seeking actively help, a bit late it seems

It doesn't state when they asked for help.

 

[|Fred]

about Japan Earthquake: nuclear plants , Meti just reported today http://www.meti.go.jp/press/20110328007/20110328007.pdf
level 0 INES event at the Toukai power plant, The concentration of radioactive materials released was less than 1 in 4,000 of legal threshold

 

[M. Bachmeier]

France, offered a week ago a few robots design to operate when men could not, Tepco or Japan , politely declined judging they were not necessary at the time. They likely reconsidered
(As far as we know Tepco did not refuse the 100t of boric acid, 3000 mask , 10 000 radiation suit, 20 000 Glove sent by Areva / EDF on the 17/18th)

Ah What, 3000 mask, 10 000 radiation suite etc...

That's anticipation or (pre)-planning for a really bad event...

I'm feeling more than just a little political at the moment...

 

[Lefteris]

It seems that plutonium was detected at the soil near the plant
http://english.kyodonews.jp/news/2011/03/81609.html

Why is it mentioned as separate news? What is the significance of it?

 

[jensjakob]

When the activity of the water is 50 times higher, the dose rate above the water is also 50 times higher, because it is the same brew of isotopes.

So yes, the dose rate in the turbine hall of unit 2 is about 30 sievert per hour.

Which makes it impossible to do work there.

Who can confirm or dismiss this calculation?

It is a serious turning point we're looking at - and it will be very interesting to get a second opinion,

 

[Reno Deano]

Yes those sample were taken on the 22 and the 23 only released today (2 hours ago)and journalist were pissed.. same for the trench with water they were tested yesterday and they only released info today..

Again as explained if you watch those Press Conference on the right inside you have a social chat and the journalist upload the document as soon as they are handled... its media 2.0 if you like.

The samples (pressurized and non-pressurized) need to be prepped to allow counting (reduce volume on high activity samples), counted several times, along with decay of high activity short lived radionuclides so the spectrum is cleaned up. Detectors can only absorb so much radiation, so samples need to be diluted or counted from a distance.

I still want to know if the upgrades to the post accident reactor coolant sampling system, performed as designed (NRC NUREG - 0737, Post TMI Action Item II.B.3). Some plants spent hundreds of thousands (some cases over a million) of dollars on these systems. I, as many, considered that the complexity of the systems would only allow it to be use once (even at that) and then buried under a pile of lead. All systems required an in-line filter (within the reactor compartment) to screen out large particles/chunks so the system's small diameter piping and pipetting apparatus would not clog up.

 

[Reno Deano]

France, offered a week ago a few robots design to operate when men could not, Tepco or Japan , politely declined judging they were not necessary at the time. They likely reconsidered
(As far as we know Tepco did not refuse the 100t of boric acid, 3000 mask , 10 000 radiation suit, 20 000 Glove sent by Areva / EDF on the 17/18th)

It is a good chance that most of the protective clothing France' sent will not properly fit the Japanese person.

 

[jensjakob]

Fukushima trenches news coverage:


High level radiation now in trenches outside Tubine building.

 

[Reno Deano]

NEI: UPDATE AS OF 1:30 P.M. EDT, MONDAY, MARCH 28:
Tokyo Electric Power Co. has detected isolated, low concentrations of plutonium in the soil at the Fukushima Daiichi nuclear power station. The density of plutonium is equivalent to the fallout that reached Japan from nuclear weapons testing during the Cold War, the company said.

TEPCO conducted analysis of plutonium contained in the soil collected on March 21 and 22 at five locations at the Fukushima Daiichi plant. Plutonium 238, 239 and 240 were detected, however just two of the samples may be the direct result of the recent incident, considering the ratio of the plutonium isotopes.

"The density detected in the plutonium is equivalent to the density in the soil under normal environmental conditions and therefore poses no major impact on human health," TEPCO said. The company said it plans to strengthen environmental monitoring inside the station and surrounding areas.

 

[Bob S]

...But I see in many articles written that the radiation is 1 Sievert/h in turbine building 2, which i interpret then as a mistake from a misleading info if I understand well: is it that difficult to have instruments measuring more than 1 sievert/h?

A properly designed radiation measuring instrument can easily measure 30 Sieverts per hour with little saturation or nonlinearity.

1 Sievert = 1 joule (of energy deposition) per Kg = 0.001 joules per gram

1 Sv/hr = 280 x 10^-9 joules per gram-sec

Because it takes about 35 eV to create an electron-ion pair in nitrogen (for example), the current in an ionization chamber would be about

1 Sv/hr = 7.9 nanoamps per gram of nitrogen gas (or air). 1 liter of air at STP is about 1.29 grams.

So 30 Sv/hr = 310 nanoamps per liter of gas in the ionization chamber.

For high dose rates, the ion chamber must be properly designed to minimize the effects of space charge (in the gas) on the electric fields in the chamber, which can affect the charge collection efficiency.

Radiation levels of this order are often seen around particle accelerators. The radiation detectors are designed to measure over 1 Sv/second. See

http://ab-div-bdi-bl-blm.web.cern.c...ectors/Literature/schaefer_biw02_tutorial.pdf

Bob S

 

[Paul F.]

New poster here.. I've been following this thread since last saturday with great interest (and varying levels of understanding).

I have a couple questions (hopefully reasonably intelligent ones).

Regarding the contaminated water in the containment basement(s);
I'm not fully understanding the nature of the radioactive contamination; is it radioactive isotopes dissolved in the water, or is it more likely particulates in suspension?
I've been wondering if some of the sea water filtration type equipment that desalinates sea water might be an effective "trap" to help decontaminate some of the water that's accumulating, or if filtration would be ineffective on dissolved elements?

Second;
Regarding the "long term" containment at the Fukushima site, after the more critical short-term stabilization and clean up occurs...
I know there's a lot we DON'T know yet, that we'll need to know more about before a "long term" plan can be developed, but in broad terms; How will the site most likely be managed in the 5 to 50 years in the future time frame?
Is it likely that Units 1, 2, and 3 will be walled up in an enormous sarcophagus building, to be dissassembled over the next 40 years?

Or (again, pending more information coming out about the states of the RPV and Containment), is it likely that substantial clean-up and removal of spent fuel in the SFP's will likely be able to happen without a giant tomb being built?


Thanks to everyone again for an outstanding, calm, rational discussion without the hype and hyperbole that the "news" talking heads have been giving.


Paul F.

 

[Demidrol]

NEI: UPDATE AS OF 1:30 P.M. EDT, MONDAY, MARCH 28:
Tokyo Electric Power Co. has detected isolated, low concentrations of plutonium in the soil at the Fukushima Daiichi nuclear power station. The density of plutonium is equivalent to the fallout that reached Japan from nuclear weapons testing during the Cold War, the company said.

Good evening!
Plutonium appears after an explosion on 3 reactor scattered?

 

[rmattila]

NEI: UPDATE AS OF 1:30 P.M. EDT, MONDAY, MARCH 28:
Tokyo Electric Power Co. has detected isolated, low concentrations of plutonium in the soil at the Fukushima Daiichi nuclear power station. The density of plutonium is equivalent to the fallout that reached Japan from nuclear weapons testing during the Cold War, the company said.

TEPCO conducted analysis of plutonium contained in the soil collected on March 21 and 22 at five locations at the Fukushima Daiichi plant. Plutonium 238, 239 and 240 were detected, however just two of the samples may be the direct result of the recent incident, considering the ratio of the plutonium isotopes.

"The density detected in the plutonium is equivalent to the density in the soil under normal environmental conditions and therefore poses no major impact on human health," TEPCO said. The company said it plans to strengthen environmental monitoring inside the station and surrounding areas.

The results can be found on the TEPCO report:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110328e14.pdf

At sampling spots 1 and 5 the ratio of Pu-238 to total Pu activity is of the order of 1..2, which means the Pu originates from fuel with burnups > 10 MWd/kgU, i.e. reactor fuel. So, even though the absolute value of the Pu activity is not significantly higher than that resulting from the atmospheric nuclear testing, its composition implies that some fuel damages have occurred in such a way that small amounts of fuel have been dispersed to the vicinity of the plant.

The locations of the sampling spots are shown there:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110328e15.pdf

 

[Paul F.]

I've been wondering about the backup generators that were flown in that had "plugs which could not be used"...

I wonder if, since part of Japan uses 50hz power, and another part uses 60hz, if it was actually a mis-match of equipment phase, rather than the physical "plug" that was mismatched?
A poor translation, perhaps?


Paul F.

 

[PietKuip]

Pietkuip, you said: "30 sievert/hour"

Ouchhhhhh...

thanks for the clarification!

But I see in many articles written that the radiation is 1 Sievert/h in turbine building 2, which i interpret then as a mistake from a misleading info if I understand well: is it that difficult to have instruments measuring more than 1 sievert/h? Again that's unbelievable so see how information is biased because of inaccuracies and again misleading infos from TEPCO... Saying it's "more than 1 Sievert/h" when it's probably 30 Sievert/h is a misleading way (as a minimum!) of saying things, don't you think?

This failure in reporting is the incompetence of journalists and "experts", at NHK and other places. Some of them get it right, though. For example this guy: http://yokosonews.com/live/ He reported accurately that the true dose rate might be several times higher. And he seems to be mainly a culture and entertainment reporter. It seems that he had his info straight from watching a Tepco press conference.

No, it is not difficult to measure higher dose rates, see a previous posting. But the workers do not carry such instruments.

I must modify my estimate a bit with a caveat: I was tacitly assuming equal depths of the water in buildings 2 and 3. Dose rates will be higher if the water is deeper, up to the screening length for gammas.

 

[Reno Deano]

A properly designed radiation measuring instrument can easily measure 30 Sieverts per hour with little saturation or nonlinearity.

1 Sievert = 1 joule (of energy deposition) per Kg = 0.001 joules per gram

1 Sv/hr = 280 x 10^-9 joules per gram-sec

Because it takes about 35 eV to create an electron-ion pair in nitrogen (for example), the current in an ionization chamber would be about

1 Sv/hr = 7.9 nanoamps per gram of nitrogen gas (or air). 1 liter of air at STP is about 1.29 grams.

So 30 Sv/hr = 310 nanoamps per liter of gas in the ionization chamber.

For high dose rates, the ion chamber must be properly designed to minimize the effects of space charge (in the gas) on the electric fields in the chamber, which can affect the charge collection efficiency.

Radiation levels of this order are often seen around particle accelerators. The radiation detectors are designed to measure over 1 Sv/second. See

http://ab-div-bdi-bl-blm.web.cern.c...ectors/Literature/schaefer_biw02_tutorial.pdf

Bob S

-----------------------------

Areas around particle accelerators are enviornmentally stable. Only post TMI reactor compartment (dry well and reactor building) gamma detectors are designed and hardened for ultra-high dose rate measurements (10^5 Sv/hr) in a degraded environment. The equipment I am referring to is off the shelf laboratory type detectors.

 

[liamdavis]

Here are a couple of radiation mapping sites for Japan. The last one is the organization that makes them possible. They are probably more of interest from an academic standpoint of examining spontaneous self-help networks since the calibration would be difficult to establish. But since they monitor radiation I thought they might be of interest, if not use, here.
Liam

http://japan.failedrobot.com/

http://www.rdtn.org/

http://community.pachube.com/node/611

 

[Demidrol]

The results can be found on the TEPCO report:
At sampling spots 1 and 5 the ratio of Pu-238 to total Pu activity is of the order of 1..2, which means the Pu originates from fuel with burnups > 10 MWd/kgU,

That is the core of the reactor?

 

[britinjapan]

Could someone comment on the existence of Plutonium that has now been confirmed in the soil - does this make the current radius around the plant likely to change? What is the possibility of Plutonium spreading through the air and water to destinations further out of the zone (80km US has deliniated?)?

I`ve read that Plutonium is heavy and does not penetrate paper, but is exteeme if inhaled. Thanks

 

[Passionflower]

According to the same article those 20 to 50% might as well be 10% when the French do the math. (assuming it's math they are doing)

Any how , make your mind by your self !
I'll leave it to you to judge of the merit of the claim (speculation really) from the Austrian Weather channel http://www.zamg.ac.at (that's the expert)
(and may be blame the journalist...)

This data is not from the 'weather channel', are you intentionally trying to discredit the report?

The New Scientists reports on the same information:
http://www.newscientist.com/article...dioactive-fallout-nears-chernobyl-levels.html

 

[M. Bachmeier]

My Nephew, who was living in Tokyo and is now coming home:

http://www.chugai-pharm.co.jp/hc/Satellite?c=CrpCorner_C&cid=1259593215924&pagename=Chugai%2FCrpClassification

Just thought I'd try to remind people that this is also a human issue. It affects all of us. Our judgment, our empirical approach, our perceived knowledge and our humanity. I guess there are some things we can't be empirical about.

 

[|Fred]

I would be more interested in the How that in the from where, and would appreciate if someone could speculate on how Pu could make his way to the location it was found?

 

[TCups]

I would be more interested in the How that in the from where, and would appreciate if someone could speculate on how Pu could make his way to the location it was found?

From a "dirty boom" at unit 3?

 

[Passionflower]

From a "dirty boom" at unit 3?

It is possible.

The longer this is going on the less I am trusting TEPCO. It appears that they have a history of lying and fudging data. And the Japanese government is asking them to provide more information. Well at least it is not begging.

See for instance:

http://online.wsj.com/article/SB10001424052748703363904576200533746195522.html

"In 2007, an earthquake heavily damaged Tepco's Kashiwazaki-Kariwa plant. The company initially said there was no release of radiation, but admitted later that the quake released radiation and spilled radioactive water into the Sea of Japan."

"In Japan in 1999, an uncontrolled nuclear chain reaction at a uranium-reprocessing plant killed two employees and spewed radioactive neutrons over the countryside. Government officials later said safety equipment at the plant was missing and the people involved lacked training, adding that their assessment of the accident's seriousness was "inadequate.""

"..The scandal was the latest in a string of nuclear safety records cover-ups by Tepco, including the revelation that the company's doctoring of safety records concerning reactor shrouds, a part of the reactors themselves, in the 1980s through the early 1990s. Five top executives resigned after the company admitted to having falsified safety."

"In 2003, Tepco shut down all of its nuclear reactors for inspections, acknowledging the systematic cover-up of inspection data showing cracks in reactors. "

"The Fukushima Daiichi plant has a black mark on its record from earlier in the last decade, when a scandal involving falsified safety records led to parent company Tepco briefly shutting down its entire nuclear fleet in Japan. In 2002, Tepco admitted to the Nuclear and Industrial Safety Agency that it had falsified the results of safety tests on the containment vessel of the No. 1 reactor, which is now one of three reactors that workers are struggling to keep from overheating. The test took place in 1991-1992. "

http://nuclear-news.net/2011/03/22/tokyo-electric-power-company-tepco-faked-nuclear-safety-records/

"The operator of the Fukushima No. 1 plant submitted a report to the country’s nuclear watchdog 10 days before the quake hit on March 11, admitting it had failed to inspect 33 pieces of equipment in its six reactors."

"A power board distributing electricity to a reactor’s temperature control valves was not examined for 11 years, and inspectors faked records, pretending to make thorough inspections when in fact they were only cursory, Tepco said."

 

[liamdavis]

Not news but an interesting article on electronics in a radioactive environment. It may address some questions some of us new folks have on the reliability of data from electronic devices in an environment such as at Fukushima.
liam

http://spectrum.ieee.org/tech-talk/semiconductors/design/radiationhardening-101

 

[Soafcom]

If the fuel grains wash out, they go with the flow. If there is no flow, then they would settle toward the bottom of the core, or down through the plenum under the core plate.

Now, with the seawater, I have to wonder if some of the fuel particles will actually dissolve, in which one then has a solution, e.g., uranyl chloride. I don't know of any research into the chemical behavior of spent fuel in seawater.

The best source I could find for seawater interactions of fission products was related to the dissolution of Plutonium Dioxide in radioisotope power generators used in space exploration:
http://www.osti.gov/bridge/servlets/purl/4839392-lrKndC/4839392.pdf

Basically, the microspheres they tested did not dissolve very well into sea water (about 0.012 - 0.016 μg/mg/day - p19) and (this isn't relevant yet, but if PuO₂ were released into the open ocean it's a good thing) if they are encrusted with marine growth their dissolution rates go down by about half (about 0.0048 - 0.0076 μg/mg/day - p19.)

This obviously doesn't take into account the presence of other compounds in close proximity that might chemically interact with the Pu.

 

[razzz]

How many pounds or tons of fuel rods in 1 of these types of working reactors then *3/50% (conservatively speaking) for a possible amount of radioactive lava?