Japan Earthquake: Nuclear Plants at Fukushima Daiichi

AI Thread Summary
The Fukushima Daiichi nuclear plant is facing significant challenges following the earthquake, with reports indicating that reactor pressure has reached dangerous levels, potentially 2.1 times capacity. TEPCO has lost control of pressure at a second unit, raising concerns about safety and management accountability. The reactor is currently off but continues to produce decay heat, necessitating cooling to prevent a meltdown. There are conflicting reports about an explosion, with indications that it may have originated from a buildup of hydrogen around the containment vessel. The situation remains serious, and TEPCO plans to flood the containment vessel with seawater as a cooling measure.
  • #14,001
Thanks for that translation Tustsuji, I hope they make some progress with their inquiry and are able to resolve some of those outstanding questions - or at least shed some additional light.

Regarding the earthquake damage - I recall reading that there were radiation alarms set off before the tsunami arrived and as the "remaining questions" list shows the state of the cooling apparatus immediately following the earthquake remains in doubt.

Clearly also there are unresolved issues about the source of hydrogen that fueled the explosion at unit 4.
 
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  • #14,002
dbl post again - must remember to explicitly log in before trying to post a reply. Any help on guidelines/tips for posting images to the thread would be appreciated.
 
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  • #14,003
http://www3.nhk.or.jp/news/genpatsu-fukushima/20130604/0445_chikasui.html Heeding to a remark by a Nuclear Regulaton Agency officer, Tepco performed a more precise measurement of the groundwater intended for release into the sea. In the past, Tepco said that the cesium 137 concentration was lower than the detection threshold. Now Tepco is providing a measurement of 0.39 Bq/l . This is lower than Tepco's internal standard of 1 Bq/l and lower than the legal requirement of 90 Bq/l. There is no prospect of starting the releases as the local fishermen have been resisting. Tepco said "we are going to politely explain to the local inhabitants that this is lower than our internal standard".

Any help on guidelines/tips for posting images to the thread would be appreciated.

What do you want to know ? If the picture is on your computer, you may use the "manage attachments" button below the edit box. If the picture is online you may type the image URL and insert it between [ I M G] [/ I M G] tags (or click on the icon above the edit box).
 
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  • #14,004
This is the image I tried to post on the previous page showing the spike in emissions after march 20th:
 

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  • #14,005
"manage attachments" worked. I tried the url and [ I M G ] tags last time and it didn't seem to work for me. Thank you Tsutsuji
 
  • #14,006
tsutsuji said:
http://www3.nhk.or.jp/news/genpatsu-fukushima/20130530/0510_kiseicho.html The NRA is starting an inspection on 30 May to investigate accident causes. They will go to unit 1 and check the circumstances of a water leak that had been reported by an employee before the tsunami struck, and whose cause remains unknown. Because of radiations, the inspection on unit 1's 4th floor, to be performed by 5 Nuclear Regulation Agency employees on 31 May will be limited to about 10 minutes. On May 1st they held their first meeting and discussed the possibility that earthquake damage took place in a unit 1 cooling system. The purpose of the inspection is to check the validity of the explanation that water from the pool flowed into the air conditioning system, by looking for equipment damage. The second meeting will be held in the beginning of June.

http://www.asahi.com/national/update/0605/TKY201306040838.html The NRA released two pictures of the inspection on unit 1's 4th floor.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130605/1010_koukai.html They took hundreds of pictures and a 40 minute long video. Maximum exposure was 4.8 mSv. Results of this inspection will be announced at the second study group meeting.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130605/1010_koukai.html A patrol found a leak from an above-ground tank at 00:15 PM today. The rate was about one drop every 3 or 4 seconds. The leak was stopped about 4 hours later as a result of tightening bolts and transferring part of the water to another tank. The total amount is about 1 l.

http://www.tepco.co.jp/nu/fukushima-np/handouts/2013/images/handouts_130605_08-j.pdf Leakage from flange of G6 area tank (cylindrical metallic tank)
 
  • #14,007
tsutsuji said:
The NRA released two pictures of the inspection on unit 1's 4th floor. [...]They took hundreds of pictures and a 40 minute long video. Maximum exposure was 4.8 mSv. Results of this inspection will be announced at the second study group meeting.

Wooo. Yet another visit and video of unit one's 4th floor. I still don't know what they were looking for during the last two visits but I find them fascinating.
 
  • #14,008
During the May inspection, the investigators were able to remain on the fourth floor of the building--where the condensers were installed--for only 15 minutes due to high levels of radiation, which were measured at 20-30 millisieverts per hour.
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201306050085

What can you learn in 15 minutes.?

Sorry, but this is ridiculous.
No one checked the availability of water in the tanks themselves, checked only tool the water.

In addition, it is clear that the valve (outside) need to be opened by hand, very quickly.
03.11.2011. Just 1.5 hours was in stock.
then on top of the reactor accumulated non-condensable gases and end all.
the condenser air pocket, it does not work....
.
 
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  • #14,009
What can you learn in 15 minutes.?

Sorry, but this is ridiculous.

I think the idea was to photograph and record video of relevant areas and to analyze the pictures after the fact. They had specific questions so the photography should have been well targeted.

We will see what they come up with.
 
  • #14,010
http://www3.nhk.or.jp/news/genpatsu-fukushima/20130619/1300_kenshutsu.html Tritium and strontium were found above the legal levels set for sea releases, in measurement wells on the sea side of unit 2. Tepco says the cause could be the April 2011 high radioactive water leaks. Tepco will reinforce the sea bank so that the water doesn't pour into the sea, and dig additional monitoring wells.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130619/index.html nearby seawater radiation levels are stable.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130619/1920_okure.html The disclosure of this well contamination problem has been two weeks late, as Tepco was aware of it as soon as 31 May 2013. However the Tepco headquarters in Tokyo learned about it only on 11 June. The time taken to reach the management and to wait for the strontium analysis results (strontium analysis requires time) resulted in the disclosure on 19 June.

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130619/1920_moushiire.html Fukushima prefecture sent a formal request to Tepco to analyse the cause and prevent sea release.

http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130619_03-e.pdf Results of Groundwater Quality Survey at the East Side of the Turbine Building at Fukushima Daiichi NPS
 
  • #14,011
http://www3.nhk.or.jp/news/genpatsu-fukushima/20130625/0730_tritium.html Seawater samples taken on 21 June 2013 in the northern part of the harbour were found with 1100 Bq/l of tritrium instead of around 100 Bq/l until last April. Although this is 50 times lower than the legal maximum level, this raises the concern that contaminated groundwater may be leaking into the sea. Tepco says the reason for the concentration rise is still unknown.

http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/2tb-east_130625_02-e.pdf Tritium Analysis Results of Seawater in the Port at Fukushima Daiichi NPS
 
  • #14,012
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  • #14,013
Your PDF reader seems to have not parsed the symbol for micro in front of the dose given (in microsieverts/h)
 
  • #14,014
Pf... Bummer.
Thanks.
 
  • #14,016
  • #14,017
Bandit127 said:
Do we think this is groundwater contaminated in the original accident now slowly making its way down to the sea?

Err... no. It has to be cooling water injected some time after the accident, which is leeching out from the cores in some way or another.

Its origin is rather inconsequential anyway...
 
  • #14,018
Are we perhaps measuring the diffusion rate of the plume of radioactive material from the damaged reactors?
I had thought that the initial plan was to keep the reactor area water level slightly below that of the surrounding area, because that would ensure ground water flows would be into, not out of, the contamination zone.
What I have no insight into is what is the diffusion rate of the various contaminants from the reactor area. That process will gradually spread the contamination, even against an inflow, because the inflows tend to be localized, while diffusion works everywhere. However, faster inflows help limit diffusive outflows.
It is probably true that TEPCO had expected to dump the treated water fairly quickly, in order to have space available for an aggressive water recirculation treatment program. That they are currently stuck storing huge volumes of basically clean water was predictable, but only in Japan. The result I believe has been that water processing has been slowed for want of storage space and that the contamination has spread more rapidly, because the rate of water inflow into the reactor area has been reduced by the slower water treatment withdrawals.
Can anyone with better physics know how that I confirm this, or put me straight if this is false?
 
  • #14,019
I fail to understand why water is stored instead of being processed by evaporator and discharged in the ocean.
Are there other isotopes beside tritium which won't be separated by distillation?
 
  • #14,020
Masao Yoshida Passes Away

Masao Yoshida, TEPCO Executive Officer (former Plant Chief of Fukushima Daiichi Nuclear Power Station), passed away aged 58, at 11:32AM on Tuesday, July 9 at a hospital in Tokyo due to esophageal cancer. He had been battling the disease for some time.
[...]


From first TEPCO press statement, 9 July 2013 (http://www.tepco.co.jp/en/press/corp-com/release/2013/1228822_5130.html).

We will remember that guy.
 
  • #14,026
  • #14,027
zapperzero said:
Any idea how much it was before the steam?
EDIT: google translate says it's the shield plug area. So the steam could be coming from the RPV.

The whole press release translated:
July 18, is the follow-up about what it was confirmed that the Unit 3 reactor building 5 floor near the center from (equipment storage pool side), steam is in the air.

I will inform you (July 23), so we conducted a radiation dose rate measured in the vicinity of the (whole shield plug) today.

The results of measurement of the 25 locations of the portion near the maximum value 2170mSv / h, a minimum 137mSv / h, the radiation dose rate of the place where it has been confirmed steam was 562mSv / h.

We will continue to watch the situation.

Seems to me like the steam is not carrying radiation with it.
 
  • #14,028
Bandit127 said:
Seems to me like the steam is not carrying radiation with it.

Based on what?
 
  • #14,029
Bandit127 said:
Seems to me like the steam is not carrying radiation with it.
How could that be? In the weeks after the meltdown they had a lot of "steam" coming out, and they got the whole shield plug activated. Here's more data (of today):
http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2013/images/handouts_130724_05-e.pdf

Seems rather they have a (one?) hotspot that occasionally, unpredictably comes in contact with water. That they cannot find with the remaining thermometers. And a containment that is incontinent not only at the bottom but also at the top (not really a new observation). Worst is the message that no plant parameters have changed. Steam was "found" on 18 July, so what happened before?

This is not what a "cold shutdown" should look like.
 
  • #14,030
zapperzero said:
Based on what?
Less radiation where the steam was coming from than the maximum they found.
 
  • #14,032
Bandit127 said:
Less radiation where the steam was coming from than the maximum they found.

It does not follow.
 
  • #14,033
  • #14,035
triumph61 said:
TEPCO's spokesman said the steam coming out of Reactor 3 in March 2011 after the explosion was from inside the Containment Vessel, and that is known to everybody.
http://ex-skf.blogspot.de/2013/07/fukushima-i-nuke-plant-reactor-3s-steam.html

So 2 1/4 years the TEPCO PR dept. found it feasible (without "losing honor") to admit what, at that time, indeed everybody understood. We then might prepare for lots of additional data that was supressed then.

On the "rainwater theory" here's a nice comment from the same Ex-SKF thread:
mscharisma said:
The fire-breathing dragon explanation for the rising steam is at least as plausible as the "rain hitting the 40 degree containment cap" explanation. My vote goes to the dragon.
*mscharisma*
July 25, 2013 at 7:43 AM

Then, even as rainwater sickers down it will eluate radioactive substances, when heated (to 40 °C!) go to gas phase, the steam will carry more particles and droplets out (most will condense though), and the expelled stuff will not be radioactive? There are two things that are not consistent.

a) The 40 °C thing. But TEPCO claims it's all cold shutdown, right?

b) The remarks by Bandit127 on the non-radioactive steam.
Bandit127 said:
Seems to me like the steam is not carrying radiation with it.
 
  • #14,036
ronaldkr said:
heated (to 40 °C!)

this is the one bit that is very grating
outside temp ~20°, humidity ~90%, but somehow water heated to 40° manages to turn into observable amounts of steam. How does that work?
 
  • #14,037
from what i understand, new temperature measures are 30.7° - 40 m above the roof - , and 34.3° - 5 m above - (Infrared thermography of the location of the steam on July 24, 2013). I'm not sure how they came up with that 40° thing they used in the first press release about the steam.

Today Tepco in a new press release stated (from ex-skf translation) :

Mechanism of steam generation

In addition to rainwater seeped in from a gap in the shield plug and warmed by the Containment Vessel head, there is an observable difference(3 m3/hr) between the amount of nigrogen gas being injected into the Reactor Pressure Vessel and Containment Vessel (16 m3/hr) and the amount of nitrogen gas being extracted (about 13 m3/hr), and it is possible that this gaseous body (3 m3/hr) containing enough water vapor is leaking through the Containment Vessel head. We presume that when the vapor leaks through the gap in the shield plug onto the 5th floor of the reactor building, it is chilled by the air which is relatively colder than the vapor, and is visualized as steam.
 
  • #14,038
Ronaldkr - I would like to retract my previous comment. Prompted by other posts I have given this further thought.

Should the steam be carrying radiation, it would deposit it if it condenses. It may condense more favourably somewhere cooler than the place it escapes from and this would explain a higher reading somewhere else.

The fact that Tepco have withdrawn workers from the area while they investigate may be due to the high readings (2.0 Sv/hr). It may also be due to them suspecting the steam is carrying radiation. "While they investigate" suggests the latter.

I don't want to believe the fire breathing dragon analogy. But if there is one, it's rear end is down in the water table I think.
 
  • #14,039
  • #14,040
Do they also get a year end bonus for helping to keep Fukushima out of the news until after the elections?
Cynicism aside, is this not the first public sanction imposed on any member of TEPCO management?
 
  • #14,041
etudiant said:
Cynicism aside, is this not the first public sanction imposed on any member of TEPCO management?
I remember a similar sanction. Possibly when the rat in the power supply incident happened, but I'm not sure.
 
  • #14,042
ronaldkr said:
This is not what a "cold shutdown" should look like.

How should a cold shutdown on a reactor that suffered core damage and a hydrogen explosion look like? I feel the plants are in a much more stable condition then one would expect for the amount of damage they took.
 
  • #14,043
Cire said:
How should a cold shutdown on a reactor that suffered core damage and a hydrogen explosion look like? I feel the plants are in a much more stable condition then one would expect for the amount of damage they took.

Well obviously talking about shutdown, cold or otherwise, when the reactors basically self destructed is just a ridiculous PR tactic.
 
  • #14,044
Cold shutdown has a specific meaning in US, temperature less than 200F and ~atmospheric pressure..

http://www.nrc.gov/reading-rm/basic-ref/glossary/cold-shutdown.html

As somebody pointed out visible vapor may not indicate active boiling. One can see one's breath on cool days.

Not that it doesn't bear watching, but don't push the 'panic' button just yet.
 
  • #14,045
Fukushima-Daiichi-Unit-3-July-2013

Looks not that bad.
 

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  • #14,046
nlsherrill said:
So, when the news reports that there is a danger of radiation exposure...what exactly is being exposed? I think I know the very basics of the core, which is essentially uranium fuel rods that are bombarded by free neutrons right? Where does Xe, Kr, and I come from? Are these what uranium decays too? When people get radiation sickness/exposure, what is harming them? electromagnetic radiation or something else?

Clearly I have no clue what I'm talking about, but I would like too.

The elements you're asking about are fission products produced from fission reactions inside the reactor ,and honestly the presence of Xe 135 would be a good thing inside the core after the accident since it absorbs neutrons and decreases the fission reactions. Of course this doesn't mean it's good for it to be released to the environment
 
  • #14,047
nikkkom said:
Fukushima-Daiichi-Unit-3-July-2013

Looks not that bad.

Doesn't look you could die by simply walking around on that exposed floor for a while. And yet...

Interesting that they've started tearing down some of the adjacecnt buildings. I didn't see that mentioned in any of the plans I read. Perhaps it falls under general rubble clearance.
 
  • #14,049
http://www3.nhk.or.jp/news/genpatsu-fukushima/20130727/index.html A sample taken on 26 July 2013 in a trench 50 m away from the sea, on the side of unit 2 was found with 2,350,000,000 Bq/l of cesium. This is a concentration of the same order as the contaminated water that leaked into the sea in April 2011 shortly after the accident. Tepco said that it is possible that this is indeed water that remains from the April 2011 leak, but as other causes are possible, no definitive conclusion can be drawn at this point.

http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/trench02_13072801-e.pdf Analysis Results of Accumulated Water at Unit 2 Seaside Trench in Fukushima Daiichi Nuclear Power Station

http://www3.nhk.or.jp/news/genpatsu-fukushima/20130729/index.html The NRA instructs Tepco to remove the contaminated water from the trench. In May 2013, Tepco started detecting higher contamination concentrations in the sea or in wells near the sea and on 22 July 2013 Tepco admitted for the first time that contaminated water leaked into the sea. The NRA specialists who met on 29 July said there is a possibility that the contaminated water runs through a gravel layer in the ground. Tepco plans to inject chemicals into the gravel layer by September 2013 in order to stop the leak, and to remove the contaminated water in April 2014 or later. However, it is thought that contaminated water from the turbine building, etc. is seeping into the trench, and the development of technology to stop such seepage has not been completed. The storage location after removal has not been decided either. For these reasons, there is no prospect of implementing a radical solution.
 
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  • #14,050
The aggregate fuel cesium load in reactors 1-3 at Fukushima was given at about 1600 kg in earlier posts.
Of this, perhaps 4 kg were believed to have vaporized during the explosive phase of the accident.
That suggests that the melted fuel still contains about 400 times the quantity of contaminant as has been released to date.
Cesium is very water soluble and it would be natural to expect the warm coolant water to leach the fuel pellets that were released during the meltdown.
That suggests that the 80,000 plus tons of water in the basements of the reactor and turbine buildings are getting steadily more cesium enriched even as TEPCO is running low on storage space for treated water.
Is something important getting overlooked here or is this a correct understanding of the situation?
 

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