Japan Earthquake: Nuclear Plants at Fukushima Daiichi

In summary: RCIC consists of a series of pumps, valves, and manifolds that allow coolant to be circulated around the reactor pressure vessel in the event of a loss of the main feedwater supply.In summary, the earthquake and tsunami may have caused a loss of coolant at the Fukushima Daiichi NPP, which could lead to a meltdown. The system for cooling the reactor core is designed to kick in in the event of a loss of feedwater, and fortunately this appears not to have happened yet.
  • #10,711
Reactor injection rate instability again :
At 5:30 pm on July 28, flow rate of injecting water to Unit 2 reactor through feed water system was adjusted to approx. 3.6m3/h after reduction of flow rate was observed.
http://www.tepco.co.jp/en/press/corp-com/release/11072902-e.html

Kurion system pump suddenly stopping again :

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110729/1335_kadouritsu.html At 5 AM 29 July it was found that one of the four pumps in the cesium removal system was stopped. This is having no consequence on the quantity of water treated. Tepco is investigating the cause [They don't say if the pump was restarted or not]. This article is also saying that the water level in the waste treatment building basements having reached 20 cm below maximum, transfer of water from units 2 and 3 turbine buildings was interrupted. This is a consequence of the poor utilization rate at the water treatment facility.

http://www.fnn-news.com/news/headlines/articles/CONN00204209.html The number of employees between 50 and 100 mSv is 1680. The number of employees above 100 mSv is 480.
 
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Engineering news on Phys.org
  • #10,713
http://www3.nhk.or.jp/news/genpatsu-fukushima/20110730/index.html the number of employees

above 250 mSv = 6
200 to 250 mSv = 2
100 to 200 mSv = 100

Among the 3410 people who had worked for one month or longer at Fukushima Daiichi as of the end of May and who must undergo a medical exam every month like checking their white blood cells or their skin, 1339 or 39% have not undergone the exam.

http://mainichi.jp/select/science/news/20110728k0000m040076000c.html A company in Ibaraki has developed a new method to adsorb contaminants. It uses silica, where 2~20 nanometer diameter holes are arranged in a regular fashion and a set of chemical compounds, which are chosen according to the substance you want to adsorb. Every gram of this new material can adsorb 20 mg of iodine or 13 mg of strontium, which converts into 65,000,000,000 Bq in the case of Sr-90. The adsorbing materials used so far adsorb Ca and Mg together with Sr and chlorine together with iodine. It is not the case with the newly developed material which selectively adsorbs iodine or strontium. They say it is cheap and several tons can be produced every day.

http://www.nikkei.com/news/category...39F9FE2E2E2E2;at=DGXZZO0195579008122009000000 Tepco released the result of the unit 1 containment vessel gas analysis. The cesium concentration is 1000 times lower than expected (20 Bq/cm³ instead of the several 10000 Bq/cm³ that were expected as a result of the RPV crack(s)). It is feared that it was dissolved into the contaminated water and flowed into the reactor building or anywhere else. Tepco says this measurement alone is not sufficient to determine the status of the reactor (like the RPV cracks). Meltdown being suspected, it is thought that fuel leaked from the RPV to the containment vessel. A similar gas analysis will be undertaken at unit 2 in the first decade of August.

http://sankei.jp.msn.com/affairs/news/110730/dst11073013040013-n1.htm When they first tried to analyse the 25 cm³ sample, they used a measurement tool with a 40,000 Bq minimum and could not detect anything. Then they performed the analysis again with a lower minimum and finally found 37 Bq/cm³ . Tepco said the following possibilities can be thought : 1) the radiation substances leaking from the RPV are diminishing 2) cesium is dissolved in water 3) it is pushed outside by the nitrogen injected as a hydrogen explosion prevention measure. The same measurement will be performed again in the future at regular intervals.

http://www.tokyo-np.co.jp/article/politics/news/CK2011072802000029.html?ref=rank Minister Goshi Hosono said he will announce next week concrete plans for the ground water shielding underground walls construction. (the other part of this article goes to the "more political thread")
 
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  • #10,715
http://www3.nhk.or.jp/news/genpatsu-fukushima/20110731/4_reikyaku.html The new unit 4 SFP cooling system is being started today for a test. The temperature is expected to reach 30~40 °C in one month's time or less. The test run of unit 1 SFP cooling system is planned for the first decade of August.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110731/2000_4gouki.html They increased the flow little by little and achieved the full flow rate of the unit 4 SFP cooling system at 12:40 PM. They plan to lower the SFP temperature from 86°C this morning to 55°C in one month's time.

http://www.nikkei.com/news/headline...19595E0EBE2E38B8DE1E3E2E5E0E2E3E386989FE2E2E2 A 50 l leak occurred at the desalination facility today. It has already been repaired and the facility has been restarted. This is decontaminated water so there is, so to speak, no radiation. At the Fukushima Daini unit 4 turbine building, an air exhaust pipe was found leaking by the team inspecting the consequences of the 31 July early morning earthquake. There is no radiation. It has been repaired with fibre reinforced plastic sheet.
 
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  • #10,716
LabratSR said:
Unit 1 Contaiment Air Sampling Results

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110730_01-e.pdf

I am absolutely intrigued by this result. If air inside containment is exactly as radioactive as air outside containment, then containment is not containing much, is it?

I'd like to read some informed interpretations of this result.
 
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  • #10,717
Jim Lagerfeld said:
I am absolutely intrigued by this result. If air inside containment is exactly as radioactive as air outside containment, then containment is not containing much, is it?

I'd like to read some informed interpretations of this result.

Not being an expert in this field, I've been wondering how it would be even possible for large amounts of Cs to exist in the containment air: the rate of release of new Cs is very low, once the fuel has been cooled down to below 500 deg C or so, and what was released earlier, has had plenty of time to get deposited on surfaces and dissolved in water.

Is there something I'm missing here?
 
  • #10,718
Jim Lagerfeld said:
... containment is not containing much, is it? ...
There is many more ambiguous terms to say the least within Tepco reports like "reactor" or "cold shutdown". We can't hope for any cold shutdown with a broken reactor (RPV), and we can't hope for any containment with a broken Dry Well and a "leaking" concrete shell. I'm well afraid everything in this mess is more or less leaking since the intatial earthquake, the consequent tsunami and the following explosions.
 
  • #10,719
rmattila said:
Not being an expert in this field, I've been wondering how it would be even possible for large amounts of Cs to exist in the containment air: the rate of release of new Cs is very low, once the fuel has been cooled down to below 500 deg C or so, and what was released earlier, has had plenty of time to get deposited on surfaces and dissolved in water.

Is there something I'm missing here?

That is a good possibility. Measuring airborne radiation at such low levels does not mean there isn't a lot of cesium inside the containment. It is very likely to have settled and deposited on every horizontal surface inside the containment. This is just as it is still measured at higher concentrations in dust and debris than in the air outside the containments and offsite. It also does not mean it will be possible to send people into the containment any time soon. Direct radiation, or "shine" from deposited fission products or unshielded corium will not show up in air samples.
 
  • #10,720
Since the containment is presumably at saturation conditions around 100 deg C, one would assume there's constant condensation of steam taking place on the outer walls of the containment. It would be very easy to assume that this constant flow of steam from the containment atmosphere to the walls would drive the Cs to the walls as well, thus reducing the atmospheric content over a period of time.
 
  • #10,722
http://www3.nhk.or.jp/news/genpatsu-fukushima/20110801/index.html The SARRY water treatment system (a set of 14 diameter 1.4 m, height 3.5 m cylindrical tanks with filtering minerals inside) installation has been completed. The system will be launched in the first decade of August. From today on they will connect the pipes and perform test runs.

http://news.tv-asahi.co.jp/ann/news/web/html/210801021.html The SARRY cylinders are shielded. The test run of SARRY starts today. The unit 4 SFP temperature has already dropped to 63° C as of 08 AM this morning. It is planned to bring it to around 30°C.

http://news24.jp/articles/2011/08/01/07187671.html Tepco found 700 tons of highly contaminated water in the Waste treatment facility's Site Bunker Building basement. It is thought that the water flowed in a pipe that connects this building with another building where contaminated water is stored. Works had been performed to enable the Site Bunker Building to receive contaminated water but the permission to do so from the NISA has not been received yet.

http://www.jiji.com/jc/c?g=soc_30&k=2011080100330 Water has started flowing in the SARRY system. It will be used as a backup of the Kurion system. If the tests are OK, it is planned to start it running with contaminated water on 5 August. The hose connecting the two Waste treatment facility buildings had been prepared in June in case more storage volume would be needed as a consequence of rainfalls. Water was not supposed to flow without the pump running, but it seems that the water flowed naturally in the hose as a result of the difference of levels.
 
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  • #10,723
Radiation level of 10 Sv/hr recorded outside in between reactors #1 and #2. Tepco has placed the area off limits and is checking on the source.

http://www.47news.jp/CN/201108/CN2011080101000992.html
 
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  • #10,724
Gary7 said:
Radiation level of 10 Sv/hr recorded outside in between reactors #1 and #2. Tepco has placed the area off limits and is checking on the source.

https://www.physicsforums.com/newreply.php?do=newreply&noquote=1&p=3430531

Here is a link to http://www.nikkei.com/news/headline/article/g=96958A9C93819595E2E3E2E0E58DE2E3E2EAE0E2E3E3E2E2E2E2E2E2"

- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out, so the true figure is possibly higher. They speculate that radioactive materials released / leaked during the initial venting (pre-explosion) may have adhered to the pipe.
 
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  • #10,725
Jim Lagerfeld said:
- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out

Goes to show how much trust we can put in TEPCO's cutely-colored site contamination maps.
I hope that worker got out of there in time :mad:
 
  • #10,726
For me, the google translates those linked webpages up there with 10mSv/h value.

Please, can somebody confirm the 10Sv/h value?
 
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  • #10,727
http://www.47news.jp/CN/201108/CN2011080101000992.html says 10 Sievert in the title and again 10 Sievert in the article with 10000 Millisievert in parentheses (１万ミリシーベルト). (I can't read most of the rest of the article without a dictionary.)
 
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  • #10,728
An article in English, presumably syndicated from Bloomberg.
http://www.sfgate.com/cgi-bin/article.cgi?f=/g/a/2011/07/31/bloomberg1376-LP8WWK6JTSEJ01-5PIJEFGJ36KM50OK194CMKAJ22.DTL"

It also states 10 Sv/h
 
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  • #10,729
So there's (let's say) 20 Sv an hour coming off some junk, outside, in the middle of everything... and nobody noticed it till now?!

Can someone help me out here?
 
  • #10,730
Well, it's inside the main ventilation stack. So it's probably leftovers from the venting process.

But I think the real question is what the hell they vented there when there's still 10+ Sv/hr five months after the accident. How big must the levels have been in early march? With all that radioactive iodine which's nearly gone by now? Several hundreds?
 
  • #10,731
Inside the stack? Okay. (The first piece I read said 'debris near the stack.')

I'll look for follow-up.

(As you said, I'm not sure that's terribly comforting anyway.)

Thanks.
 
  • #10,732
Jim Lagerfeld said:
Here is a link to http://www.nikkei.com/news/headline/article/g=96958A9C93819595E2E3E2E0E58DE2E3E2EAE0E2E3E3E2E2E2E2E2E2"

- the story says that the radiation was recorded on the outside surface of some external 'ventilation' plumbing near to the ground between reactors 1 & 2 by a worker clearing rubble. The upper limit of his meter is 10 Sv/hr and it maxed out, so the true figure is possibly higher. They speculate that radioactive materials released / leaked during the initial venting (pre-explosion) may have adhered to the pipe.

Should this be a surprise?
When there are three cores worth of material getting leached for months, one would expect every surface in the facility to be dripping with redeposited cesium, especially the venting paths.
What it says to me is that there is no rational way forward other than to drain the water and then bury the facility.
It surely would be irresponsible to have people risk their lives to dismantle a massive site just to rebury the debris elsewhere. Plus the burial need only last for a thousand years or so. By then, the cesium will have decayed.
 
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  • #10,733
Using the Freedom of Information Act, UCS obtained the Draft State of the Art Reactor Consequences Analysis (SOARCA) Report which analyzes the response of the Beach Bottom plant in Pennsylvania for a seismic event resulting in Station Blackout. The analysis includes unmitigated short and long-term SBO responses with and without mitigation steps by operators. Thisw is the first quantification I have seen of the use of B.5.b systems added to US plants after the 9/11 attacks. The unmitigated long-term SBO scenario may be useful in comparing the BWR4 response at Fukushima (RCIC plants).

Go to the ADAMS search page at www.NRC.gov[/URL] and search for the following ML numbers:

Report

ML11168A034

Appendix A Peach Bottom (3 parts)

ML11192A300
ML11192A301
ML11192A302

Edit: Rod Adams at Atomic Insights has some interesting observations about UCS and the SOARCA report here:

[PLAIN]http://atomicinsights.com/2011/08/spreading-calm-certainty-and-reassurance-about-nuclear-energy-counteracting-focused-fud.html
 
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  • #10,734
My translation of Mainichi's article on the 10 Sv/hr reading:

On August 1st Tepco announced the observation of very high radiation of more than 10 sieverts (10000 millisieverts), high enough to exceed the limit of the measurement devices and the highest value seen since the beginning of the meltdown accidents, coming from the area near the surface of a pipe from the lower part of the exhaust tower on the west side of the #1 and #2 reactor buildings. 10 sieverts is extremely high, and would result in death for virtually everyone exposed to this amount. The workers at Fukushima Daiichi who have had their maximum exposure limit set at 250 millisieverts/hr would reach their maximum allowed limits at about a minute and a half of exposure to 10 sieverts.

Tepco says they have forbidden entrance to the area to a radius of a few meters, and that they will use metal plates to shield off the area so that work in that area will not be affected. They noted that if they find places with similarly high radiation it could affect work to bring the plant under control. Thorough and complete management of radioactive areas, including detailed surveys to ensure there are no other areas of high radiation, will be necessary to avoid exposing the workers to unnecessary exposure.

According to Tepco, at around 2pm on the 1st a worker noticed a change in the dosimeter reading after clearing away rubble. The pipe that had the high radiation is used in emergencies for carrying exhaust away from the inside of the reactor building. Tepco believes the high radiation may have come from either highly radioactive gasses that were stuck in the pipe after reactor #1 was vented to reduce pressure in the reactor containment on March 12th, or that radioactive particles from outside had settled on the outside of the pipe. The pipe is not currently in use. The highest recorded radiation up until now had been 4000 millisieverts, discovered inside the reactor building of #1.

The 3 Tepco employees who measured the radiation had a maximum estimated exposure of 4 millisieverts. There were few employees who worked near this area, and there has been no confirmation of any workers receiveing a large amount of radiation.

http://mainichi.jp/select/jiken/news/20110802k0000m040063000c.html

Also attaching the latest (July 31st) radiation survey map. As of this point the 10 Sv/hr spot had not been identified.

http://www.tepco.co.jp/nu/fukushima-np/f1/images/f1-sv-20110801-j.pdf
 
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  • #10,736
http://www3.nhk.or.jp/news/genpatsu-fukushima/20110802/0625_shiunten.html Tepco plans to own by next October 8 evaporative concentration equipments in addition to the present reverse osmosis equipments, 2 of which have already been put on location as of 1 August. They are now tested and will be launched in one week's time. Together with 3 more that are to be brought this month, they will have a desalination capacity of 160 tons/day.

[URL]http://www.tepco.co.jp/en/news/110311/images/110801_3t.jpg[/URL]
Evaporative concentration equipment manufactured by Toshiba (http://www.tepco.co.jp/en/news/110311/images/110801_3.jpg)
 
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  • #10,737
You are tireless, tsutsuji.

I admire and applaud your effort.
 
  • #10,738
Yes, thanks very much for these translations & news updates, its really helpful.

I've not had much to say for some weeks now, the sorts of things I'd like to know are unlikely to be known for a long time. This > 10 Sieverts stuff interests me, I'd like to know whether it came from reactor 1 or 2. Reactor 2 is thought to have contributed around 90% of total emissions from the early days of the disaster, but I don't think we have any visual evidence that venting via the stack happened for reactor 2.

There is the following webcam image from 3pm on March 12th, where something may be happening at the top of the stack in question, and which I assume is due to reactor 1?

20110312150101.jpg
 
  • #10,740
tsutsuji said:
http://www3.nhk.or.jp/news/genpatsu-fukushima/20110802/index.html The robot found more than 5000 msV/hour in a room on unit 1 reactor building 2nd floor. The 10,000 mSv/hour pipe mentioned yesterday runs across that room.

A Bloomberg report about the same thing here:
http://www.bloomberg.com/news/2011-08-02/tepco-reports-second-deadly-radiation-reading-at-fukushima-plant.html"
 
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  • #10,741
SteveElbows said:
There is the following webcam image from 3pm on March 12th, where something may be happening at the top of the stack in question, and which I assume is due to reactor 1?

Fyi, that stack receives vents from both Units 1 and 2 http://3.bp.blogspot.com/-tkSlPJ7D6fA/TZXteYtJ7yI/AAAAAAAAh7s/XpV9Ky3YKXU/s1600/9.jpg". But for reasons cited in the replies just above this, the source for these new high readings seems to be Unit 1.
 
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  • #10,742
I found an image of the highly dangerous 10 Sv/hr spot on www.tec-sim.de[/URL] !

[PLAIN][URL]http://tec-sim.de/images/stories/10svha.jpg[/URL]

According to the german description it's the brown tube coming out of the big stack.
 
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  • #10,743
i would guess it's a small but extremely hot piece of something
were the whole inside of that pipe filled with the stuff i doubt he'd be able get that close to it.
it's likely something that has been around neutrons(near reactor core) .

i'll keep ears open for more info as to what that pipe does and when it was used since the accident.
If indeed it's an emergency containmnent vent line then a hot particle in it would seem consistent with primary venting that first weekend.

Bloomberg included a "gamma camera image" but I'm not skilled enough to make it appear.
http://www.bloomberg.com/photo/tepco-reports-second-deadly-radiation-reading-at-nuclear-rea-/90617.html

old jim
 
  • #10,744
Does this not mean that the stack emissions were the primary source of the contamination plumes that Japan is now starting to focus on? It seems to indicate that the explosions may have played second fiddle to the stack emissions in propagating the radioactivity beyond the plant boundaries.
An earlier posting had noted that the stack emissions for the Swedish reactors are put through a large absorption bed. Should this not be a requirement generally, along with the hardened stack?
 
  • #10,745
etudiant said:
Does this not mean that the stack emissions were the primary source of the contamination plumes that Japan is now starting to focus on?

No. Other than that, you are correct, of course. Vents _should_ be hardened and provided with scrubbers&/filters. Google Cockcroft's Folly.
 

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