Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[MadderDoc]

This confirms the leak between the reactor pit and the pool between March 15 and 20, which is assumed to have saved the fuel in the pool from worse damage.

I am wondering how much of the temperature of the water in the reactor pit can be explained by heat conduction through the gate separating them. The reactor well itself sits insulated inside the containment, so not that much heat should flow via its walls.

Right, I am wondering about that too, joewein. Suppose we once knew ( or thought we knew) that the gate between pit and pool was closed and watertight, and someone came to this forum with the theory that the pit heat signature in the thermographs could be explained by conduction of heat through the gate, would he be taken seriously? I don't think he would.

 

[tsutsuji]

Tokyo Shinbun has the results of the tests performed at the Water purifying facility : http://www.tokyo-np.co.jp/article/national/news/CK2011062002000169.html?ref=rank

Definitions of the tests :
(1) removing any material from the tower
(2) filling the tower with a chemical agent that takes oil
(3) filling with zeolite

The test is performed for 4 hours using highly contaminated water.

Radiation measured during the test
(1) 11.55 mSv/h
(2) 4.85 mSv/h
(3) 6.60 mSv/h

Radiation measured after flushing
(1) 0.4 mSv/h
(2) 0.4 mSv/h
(3) 1.74 mSv/h

"From these differences, TEPCO concludes that while zeolite absorbs radioactive substances to some degree, there is a high probability that the measuring instrument on the surface of the tower combines the high radiation coming from the contaminated water".

 

[razzz]

http://www3.nhk.or.jp/daily/english/20_13.html



This is bad if the initial monthly change has to be revised to 5 hours due to an elevated density ...
2 orders of magnitude shift in projected contamination ?
What would this do for the schedule ?
I suspect they do not know yet why , and this would be the simplest explanation , allthough it then means they were wrong on the total level of contamination from the start

Storing radioactive water in an oil tanker is looking better by the minute. I'd being laying the transfer pipe offshore right now just in case.

Anyone have a better idea to keep the site workable?

 

[tsutsuji]

A series of diagrams explaining the water level problem in the reactor and in the pit of unit 4 : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110620_02-e.pdf

("Unit 1" is a translation mistake. Compare with Japanese version : http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110620_02-j.pdf )

A series of large size pictures from the early days of the accident : http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110620_05-j.pdf ( meant to be viewed together with the first response report http://www.tepco.co.jp/en/press/corp-com/release/11061805-e.html )

Page 5 : a stray tank blocking a road.
The last picture seems to be the black or grayish smoke event at unit 3 on March 21st (although it is merely captioned as "unit 3 outer view after explosion")

 

[MadderDoc]

westfield, joewein, thank you for considerations and your inputs to this question:

I wonder if anyone here has been able to identify where this photo was taken?

http://www.tepco.co.jp/en/news/110311/images/110611_05.jpg
<..>

Considering everything I end up with, albeit not conclusively, that the camera is in the 4th floor of unit 4, somewhat west of the center of the floor, and pointing NNE, towards the panel in the north wall that was blown out by the events on March 15th, If true this has certain implications: There is light coming from above, that implies there must be non-design holes in the servicefloor above. There is light coming in apparently through a missing panel to the west of the aforementioned blown out panel. This implies some further deconstruction either intentionally or intentionally with removal of panel(s) has occurred on the north wall of the building. (and this can be confirmed looking at some of the most recent photos shot from the ground).

The machinery seen to the right along the wall would, I believe, most likely be the M/G sets for the reactor circulation pumps. There has been reported fires in the 4th floor in a most confusing way involving the oil from the M/G sets of either or both units 3 and 4. However there is afaics no evidence of a lubricant fire in this photo.

 

[SteveElbows]

The sensible thing to do would be to progress from the lightly radioactive water used last week for testing to the next more radioactive water in storage.

At the end of the day, one cubic meter freed up is a cubic meter, doesn't matter how contaminated it was if it can now be reused for cooling instead of 500 t of additional water per day from the dam.

You don't want to have the most radioactive water from the unit 2 basement in the system while you still iron out the kinks. I assume that's what they would be doing too. Even more surprising then when they should declare that things are going wrong because the water was too radioactive!

I think the problem is that its the highly contaminated water that they are running out of storage capacity for, dealing with the less contaminated stuff does not really help them in the struggle to prevent overflow. So far I think they only have permission to store the highly contaminated water in a few locations, and those are pretty much full.

They were so desperate that the other day they even tried to move some water from reactor 2 to reactor 1 condenser, but I believe a pump failed so it didnt happen.

I imagine it is well possible that they will end up trying to store highly contaminated water elsewhere, as a last resort against site flooding/escape into sea, but I guess they will leave this till the last minute as storing very radioactive water in less than ideal locations probably comes with new risks.

 

[SteveElbows]

It's good to see the IAEA is as committed to transparency as ever. The 151 IAEA member states will meet this week in Vienna for 5 days.
http://www.bloomberg.com/news/2011-06-20/fukushima-disaster-failures-kept-behind-closed-doors-at-un-atomic-meeting.html

I will likely talk about this in the more political thread later today.

In the meantime I had completely missed the fact that there is a video of the IAEA visit to the plant, I had only seen the photo before:



I don't think I had realized how wet the dry cask storage building got before I saw this video.

 

[ThomS]

People got around 10 particles each in Tokyo. The data is from air filters in Japan and the West Coast.

How do you know that? Source?

Many thanks.

 

[zapperzero]

The last picture seems to be the black or grayish smoke event at unit 3 on March 21st (although it is merely captioned as "unit 3 outer view after explosion")

There's a concrete mixer truck in that picture. I wonder what it's doing there.

 

[joewein]

There's a concrete mixer truck in that picture. I wonder what it's doing there.

There are other possible explanations, but during one annual Japanese earthquake drill (1 September, Great Kanto quake anniversary) I have seen concrete mixers demonstrated as emergency water transport vehicles to help fire fighting. They can carry several tons of water and can pour it into pumps.

This idea came out of the Kobe earthquake, where the majority of victims did not die in the quake but subsequently burnt to death in fires when the mains hydrants broke and there was no water for putting out fires.

It might be something different, but the dark smoke from unit 3 next to it reminds me of that.

 

[Jorge Stolfi]

Tokyo Shinbun has the results of the tests performed at the Water purifying
Radiation measured during the test
(1) 11.55 mSv/h
(2) 4.85 mSv/h
(3) 6.60 mSv/h

Radiation measured after flushing
(1) 0.4 mSv/h
(2) 0.4 mSv/h
(3) 1.74 mSv/h

"From these differences, TEPCO concludes that while zeolite absorbs radioactive substances to some degree, there is a high probability that the measuring instrument on the surface of the tower combines the high radiation coming from the contaminated water".

I don't know what to make of these numbers. Is this good news or bad news?

 

[joewein]

I don't know what to make of these numbers. Is this good news or bad news?

The way I read it, it means the filters measure highly radioactive after operating for a while not because they've absorbed a lot of isotopes already but because they're soaked in plenty of highly radioactive water that has yet to pass several more purification steps. Once you flush out that water the levels are much lower again.

Did I understand the numbers correctly?

 

[etudiant]

If it is that simple, then they can just raise the threshold from 4 to 8 mSv, knowing that 4mSv come from the entrained water.
Just need to be sure to backwash before changing out thye filters./

 

[MadderDoc]

There's a concrete mixer truck in that picture. I wonder what it's doing there.

Probably nothing. It's in the same position as it was in imagery taken shortly after the tsunami.

 

[tsutsuji]

Tepco is now working to figure out how the process of removing radioactive material can be evened out among the six cartridges.
http://online.wsj.com/article/SB10001424052702303936704576397220194086998.html

Each cartridge has its own radiation sensor. If they manage to lower the radiation on the first cartridge by using a filtering material that is less efficient, then I guess the high radiation problem might occur on the second cartridge. Also they may want to ignore the sensors while the contaminated water is inside, then perform flushing on a regular basis and read the sensors only during the intervals when flushing is performed.

 

[SteveElbows]

OK here is IAEA documentation from their conference:

http://www-pub.iaea.org/MTCD/Meetings/cn200_documentation.asp

I believe the 3rd and 4th links are the report to IAEA by Japan, which we have already seen.

The 2nd link on the page contains the long IAEA report. I've not read it all yet, but after reaching page 44 I tentatively conclude that its what we may have expected, in that there is nothing much new in it at all. This is not too surprising as its mostly based on documents we have already seen, and it is not exactly crammed with technical detail. The language used when describing events is generally easier to understand, so I suppose there is a chance that it will clear up some ambiguities, but don't expect much really.

 

[MadderDoc]

<..> there is nothing much new in it at all.

Considering this is supposed to be a report of a 'fact finding mission' that's already a pretty damning thing to say. It's a watered out soup of already known facts and banalities bound in virtual brown leather and a fine IAEA logo, a total waste of time. I'd rather rehash an old T-Hawk video.

 

[etudiant]

Considering this is supposed to be a report of a 'fact finding mission' that's already a pretty damning thing to say. It's a watered out soup of already known facts and banalities bound in virtual brown leather and a fine IAEA logo, a total waste of time. I'd rather rehash an old T-Hawk video.

It is sad that the world's nuclear leadership is so frightened of the political process that it speaks only bromides. It relinquishes its chance to state its case by default.
A compelling argument can be made for nuclear power, especially if all the externalities such as mercury emissions from coal or water contamination from drilling are factored in. Yet the nuclear industry goes on pretending that it must be 99.44% pure, just like Ivory Soap. This nonsense is destructive to the credibility of the industry as well as to the emergence of better safety practices.
The essential truth is that problems denied are automatically magnified. The better approach is to 'paint it red', make it super conspicuous so that you have to deal with it in a way that everyone understands, even if they do not agree with it. That may mean early retirement for the Mk 1 reactors, because they are too vulnerable, but better an amputation than whole body gangrene.
My $0.02.

 

[zapperzero]

I suppose there is a chance that it will clear up some ambiguities, but don't expect much really.

Oh, I wouldn't say that. From
http://www-pub.iaea.org/MTCD/Meetin...tion/cn200_Final-Fukushima-Mission_Report.pdf

Conclusion 3: There were insufficient defence-in-depth provisions for tsunami hazards. In particular:
 although tsunami hazards were considered both in the site evaluation and the design of the Fukushima Dai-ichi NPP as described during the meetings and the expected tsunami height was increased to 5.7 m (without changing the licensing documents) after 2002, the tsunami hazard was underestimated;
 thus, considering that in reality a ‘dry site’ was not provided for these operating NPPs, the additional protective measures taken as result of the evaluation conducted after 2002 were not sufficient to cope with the high tsunami run up values and all associated hazardous phenomena (hydrodynamic forces and dynamic impact of large debris with high energy);
 moreover, those additional protective measures were not reviewed and approved by the regulatory authority;

The resulting ground acceleration at Units 1, 4 and 6 did not exceed the standard seismic ground motion, whereas at Units 2, 3 and 5, the resulting ground acceleration did exceed the standard seismic ground motion. The tsunami exceeded the design basis at all units.

Alignment of the valves to vent the Unit 2 containment was carried out on 13 March by opening an air operated valve using an air cylinder and another valve with AC power supplied by an engine generator. After the Unit 3 explosion, discussed below, the valve was rendered inoperable. The operators then attempted to open another air operated valve to establish the vent path. An engine driven air compressor and AC power supplied by an engine generator were used and the valve appeared to open slightly. However, the successful venting of the Unit 2 containment could not be verified.

The heat transfer path from the core and the spent fuel pool to the ultimate heat sink is very important. The ultimate heat sink of Fukushima Dai-ni NPP units 1-4 is sea water of Pacific Ocean, there are two trains of heat removal system for each unit, their seawater cooling system (RHR-S) are located in the relevant Heat Exchange Building (Hx/B), the motor of the RHR-S is located in 1F pump room (4 m above the sea level), and their power centres are located in the B1F control panel of Hx/B. Due to the tsunami (maximum run-up height of approximately 14 m) on 11 March, all of them except RHR-S-3B are submerged and damaged, so the path to removal the decay heat in the core and spent fuel pool to the ultimate heat sink (Pacific ocean) is broken. The survival of RHR-S-3B is just due to luck that is why unit 3 can reach cold shutdown state more early than Unit 1, 2, 4. The site superintendent reported the central and local governments nuclear emergency situation because the temperature of the suppression pools of Unit 1,2,4 became more than 100 ℃ during accident, but afterward with temporary power cable laid and urgent procurement of motors, one train of RHRS, RHRC, EECW for each unit of Unit 1,2,4 has recovered and restarted. Up to now, all units of Fukushima Dai-ni have reached cold shut states.

At Dai-ichi the events progressed much too fast for operators to respond in an organized manner. Normally the mission times of IC/RCIC should have given the operators some time before the core was exposed and radiation levels increased making several reactor areas inaccessible. It is not clear if and why these systems did not function the way they should have.

Unavailability of measurements has resulted in initiating urgent protection action based on the plant status. The fast changing plant circumstances made it imperative to take several consecutive measures (mostly evacuations) to protect the residents. Long term sheltering was not in line with international practice and has been abandoned and the notions of ―deliberate evacuation‖ and ―evacuation-prepared area‖ were introduced instead.
4 – LESSONS LEARNED __/__/2011 1. Use of long term sheltering (―in-house evacuation‖) was an unusual and not fully justified action that will need further analysis in the future.

On 15 March MEXT became the central agency for environmental monitoring. From 18 March the monitoring has been enhanced and reinforced (aerial, oceanic, land). Some important support from IAEA and US-DOE contributed to the improvement. Sophisticated monitoring equipments are in use (mobile units, aircraft, ships…). The most significant exposure ways are currently monitored, including land, marine and sky. Monitoring items include:
IAEA
136
o Dose rate. Fixed post and mobile units, aircrafts and ships
o Integrated dose at fixed monitoring posts
o Radionuclide analyses (mainly I-131 and Cs-137)
 Dust, soil, pond water, weed
 Drinking water, fallout (47 Prefectures)
 Sea water and sea bottom soil

bolding mine

EDIT: I am loath to parse it again, but another important thing they are saying is the IC in unit one and the RCIC in units 2 and 3 failed - i.e. ceased to perform their function adequately way earlier than they should have.

 

[MiceAndMen]

OK here is IAEA documentation from their conference:

http://www-pub.iaea.org/MTCD/Meetings/cn200_documentation.asp

I believe the 3rd and 4th links are the report to IAEA by Japan, which we have already seen.

The 2nd link on the page contains the long IAEA report. I've not read it all yet, but after reaching page 44 I tentatively conclude that its what we may have expected, in that there is nothing much new in it at all. This is not too surprising as its mostly based on documents we have already seen, and it is not exactly crammed with technical detail. The language used when describing events is generally easier to understand, so I suppose there is a chance that it will clear up some ambiguities, but don't expect much really.

Thanks for finding the link to the report. It answers, in part, why we saw so few pictures of the IAEA team at the Dai-ichi plant. They were there for less than 4 hours according to page 146 (page 148 of the pdf). The day before, they spent 5 hours at the Dai-ini plant. Apparently most of their time was spent in meetings and technical discussions, which is reasonable I guess.

In hindsight, we knew very little in the first hours and days after 11 March, but re-reading the first couple of pages in this thread is very enlightening in a not-good sort of way. Extraordinary events have taken place that were thought to have an infinitesimal chance of occurring.

 

[etudiant]

Thanks for finding the link to the report. It answers, in part, why we saw so few pictures of the IAEA team at the Dai-ichi plant. They were there for less than 4 hours according to page 146 (page 148 of the pdf). The day before, they spent 5 hours at the Dai-ini plant. Apparently most of their time was spent in meetings and technical discussions, which is reasonable I guess.

In hindsight, we knew very little in the first hours and days after 11 March, but re-reading the first couple of pages in this thread is very enlightening in a not-good sort of way. Extraordinary events have taken place that were thought to have an infinitesimal chance of occurring.

The surprise to me was that there existed detailed analyses done by the NRC that indicated a meltdown within half a day of loosing cooling. Awareness of that little detail would have put everyone on the same page very early.
Whether it would have changed any actions or outcomes is a separate issue.

 

[imandylite]

UK Government secret documents on the Fukushima Disaster released through freedom of information request.

http://www.guardian.co.uk/science/2011/jun/20/japan-earthquake-and-tsunami-japan"

http://www.scribd.com/fullscreen/58313487?access_key=key-1amf2uutax7h93geh699"

Many interesting details in the documents - some talked about here.

 

[MadderDoc]

Oh, I wouldn't say that. From
http://www-pub.iaea.org/MTCD/Meetin...tion/cn200_Final-Fukushima-Mission_Report.pdf

<..snipped a lot> just kept this tidbit from what you quoted which illustrates well why I am disgusted with this 'fact finding mission' report.

After the Unit 3 explosion, discussed below, the valve was rendered inoperable.

So, what fact is expressed here? Is it perchance an expression of cause and effect? Or is it an expression of timing of events? The answer is blowing in the wind.

Also this piece of gold, not one of those you quoted:

Because of the lack of
instrumentation and high radiation levels, the water levels in the SFPs of Units 1–4 could not
be determined in the first several days of the accident. However, the explosions at the site
destroyed the reactor building roofs of Units 1, 3 and 4, providing access to the SFPs.

So, are we to understand that high radiation at the plant already from the morning of March the 12th made it impossible to send a man to each service floor to check the situation around the pools? Is that a fact or is it hokum? Are we to understand that absent the saving grace of three explosions it would have been impossible to gain 'access' to those pools? Access? Exactly what kind of 'access' are we talking about? Access in the sense that one now could (only) look into the pools from a safe distance in a helicopter, what kind of access is that?

Yes I am sure I am overreacting. Calm down old bear.

 

[tsutsuji]

Areva's water purification system possesses its own oil removal system and would be able to perform the whole purification task alone, should the Kurion system become unavailable : http://www.sciencesetavenir.fr/actu...-traitement-peine-a-demarrer-a-fukushima.html

 

[~kujala~]

I just noticed something... I thought earlier that if there was a flow of contaminated groundwater into the sea we would see this in the radioactive levels of seawater (= increasing levels). Well, this happens to be a completely false idea:

"Underground water flows at a speed of about 5 to 10 centimeters a day, so we have more than a year before it reaches the shore."

http://mdn.mainichi.jp/perspectives/column/archive/news/2011/06/20110620p2a00m0na005000c.html

This means basically that if the deeper groundwater (= groundwater below the sub-drains) is now heavily polluted it could take a year until we will see the radioactive levels of seawater rising...

Could this be the reason (besides money) that TEPCO is not talking so much about the groundwater contamination? They think they have time.

 

[SteveElbows]

Oh, I wouldn't say that. From
http://www-pub.iaea.org/MTCD/Meetin...tion/cn200_Final-Fukushima-Mission_Report.pdf

bolding mine

EDIT: I am loath to parse it again, but another important thing they are saying is the IC in unit one and the RCIC in units 2 and 3 failed - i.e. ceased to perform their function adequately way earlier than they should have.

A large amount of the stuff you highlighted is not actually brand new information. But it might be the first time that some of the information is presented in a way that means something to many people. As well as language issues, TEPCO & Japanese authorities have sometimes failed to explain the significance of certain details they announce, to weave such details into the bigger picture in a helpful way.

In any case a lot of my complaint that there isn't much new information is not really supposed to be a criticism of the IAEA report, just a reflection of the fact that the detailed documents upon which most of this reporting is based were already made available to us in prior weeks.

Anyway, the large number of 'lessons learned' in these documents seem mostly sensible, although its hard not to laugh or cry about some of them, the very idea that we had not learned these lessons until now! For example on page 113:

The presence of high radiation fields in the plant needs to be considered to ensure manual actions can be executed under accident conditions.

This is a pretty good example of a wider failing that becomes apparent as we read all of these lessons. Safety systems & procedures are designed to try to prevent things from getting bad, but are not much use once things reach a certain bad point. This is painfully clear with areas such as instrumentation, shocking how blind the operators were to the conditions at crucial moments due to instrument failure, and lack of relaible data continues to hamper the quest for knowledge to this date.

 

[SteveElbows]

<..snipped a lot> just kept this tidbit from what you quoted which illustrates well why I am disgusted with this 'fact finding mission' report.



So, what fact is expressed here? Is it perchance an expression of cause and effect? Or is it an expression of timing of events? The answer is blowing in the wind.

Look elsewhere for the underlying facts, and just treat the IAEA stuff as a useful additional narrative. I am pretty sure that in some of the more technical documentation we've discussed here in recent weeks, there was reference to certain equipment at reactor 2 being taken out of action by the explosion at 3, and I would assume this is what they are referring to. I don't have time to find the exact detail right now but will post it when I next stumble upon it.

So, are we to understand that high radiation at the plant already from the morning of March the 12th made it impossible to send a man to each service floor to check the situation around the pools? Is that a fact or is it hokum? Are we to understand that absent the saving grace of three explosions it would have been impossible to gain 'access' to those pools? Access? Exactly what kind of 'access' are we talking about? Access in the sense that one now could (only) look into the pools from a safe distance in a helicopter, what kind of access is that?

Yes I am sure I am overreacting. Calm down old bear.

They are a bit vague on the timescale. The pools may not have been in a dangerous state early on, and so the need to check them would come days later, once things on site had got much trickier and where they may not have been keen to have humans present on service floors in any of the reactors. We don't really have much detail on the realities of this, eg we still don't know if humans removed the reactor 2 building blowout panel or not. Earthquakes causing pool water sloshing is a known issue that has had to be dealt with in the past, though I doubt it would cause enough water loss to cause pool shielding issues. If an earthquake caused additional damage to pool integrity then water may drop to a level where shielding becomes an issue much more quickly.

As for access, I think they mean access to spray water. Its a valid point even if it seems absurd when viewed from certain angles. If a pool with plenty of heat like reactor 4's was in urgent need of more water, and normal means to inject water was unavailable, and the building was still intact, then that would be a bigger problem than what they actually had to deal with. Sure, it is possible to argue that if the building had not exploded in the first place, it is more likely that more normal methods for injecting water (some pipes) would still be available, which is why I say it is a silly point in some ways.

 

[Most Curious]

Has anyone seen a time line of when building radiation levels became too high to allow human entry? I would assume shortly after fuel damage began, prior to explosions, that rad levels were already way too high for entry.

I base this on very hot reactors degrading containment seals early in the accident, loss of suppression function when pools were reported at 100C followed within a few hours by severe contamination as the fuel rod integrity was lost.

IOW, I suspect conditions were right for severe building contamination as soon as fuel damage began. At that point would anyone have ventured to the service floor for ANY reason?

 

[MadderDoc]

Look elsewhere for the underlying facts, and just treat the IAEA stuff as a useful additional narrative.

IMO you are much to kind. I'd say: look elsewhere as close to the original stuff as you can get, and treat the IAEA report as you would a poorly recompressed video coming with lost information and wooly artefacts.

They are a bit vague on the timescale. <..>

Definitely, but the worst is that they are producing pretentious nonsense, which lures the positively inclined reader into fetching some sense from his own head to fill in the void. Naturally said positive reader will then think that it was the nonsense that made the sense, not himself. Quite like when people have come here to insist there is smoke from reactors which they have dreamt up from looking at compression artefacts with a smoke-positive mind.

 

[joewein]

Could this be the reason (besides money) that TEPCO is not talking so much about the groundwater contamination? They think they have time.

TEPCO is considering walls to be built into the ground around the plant to isolate the groundwater.

See text and illustrations on page 11 on:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110617e4.pdf

II. Mitigation
(4) Groundwater
(...)

Countermeasure [68]
Examination of shielding wall of groundwater

- Considering underground water flow based on seepage analysis

<next step>
-Implement most appropriate method to shield underground water by evaluating water shield effect, earthquake resistance, durability, etc.
-Implement study for optimization of shielding section, installation plan and construction schedule

 

[etudiant]

Given the immediate problems TEPCO has, most notably a near overflowing super contaminated site,
they can be excused for believing that putting this ground water problem on the back burner is justified.
My only question is that this seems to rely pretty much on the idea that the contamination diffuses through the ground water, rather than getting streamed in bulk flows.
Whether that is a safe assumption given that the area has just had a substantial shifting from the quake is not obvious.

 

[Jorge Stolfi]

One thing that I find most disturbing is that TEPCO's knowledge of the state of reactors #1-#3, three months after the accident, is still entirely based on a dozen or so analog instruments, many of them clearly busted. Vital information, like water level and vessel pressure, are being read out from manometers that would look fine on Captain Nemo's control panel.

One would hope that more modern plants have better instrumentation; so that, in case of a severe accident, the operators would be able to tell whether and where the RPV is leaking, whether and to what extent the fuel has been damaged, whether there is corium on the drywell floor, and so on.

However, I suspect that modern plants may be even worse in this regard. Instruments seem to be increasingly based on digital electronics, which may not last long in case of an extended power failure and severe radiation leaks such as those now present at Fukushima. Is this the case?

(They recently found the black box of the Rio-Paris flight that fell in the ocean a while ago. According to the newspapers, the pilots started to climb in order to avoid a storm, but the plane stalled, lost speed and started to fall. They could have recovered easily, but were misled by the intruments. The pitot tubes did register ~100 km/h, but the on-board computer decided that such a low speed was absurd and could only be an instrument failure; it 'censored' that information and displayed a much higher assumed speed to the pilots instead. So they did not understand what was happening until it was too late. In this aspect, it reminds me of TMI...)

So, are we to understand that high radiation at the plant already from the morning of March the 12th made it impossible to send a man to each service floor to check the situation around the pools? Is that a fact or is it hokum? Are we to understand that absent the saving grace of three explosions it would have been impossible to gain 'access' to those pools?

Ming-boggling.

Presumably the regulating bodies will now recommend all exising nuclear plants to be upgraded by installation of redundant automatically triggered HTEDBAFs (Hydrogen Tanks for Emergency Direct Building Access Facilitation) on the service spaces.

 

[sigyn]

Please, are there some data as to oceanic radioactive contamination from Fukushima ? I have not seen anything lately, but I see that the Kuroshio carries to Alaska where McDonalds does get most of the fish fillets.

sigyn

 

[joewein]

One would hope that more modern plants have better instrumentation; so that, in case of a severe accident, the operators would be able to tell whether and where the RPV is leaking, whether and to what extent the fuel has been damaged, whether there is corium on the drywell floor, and so on.

For what it's worth, when the Monju FBR caught fire in 1995, half a year after entering testing, their fire alarm could say there was a fire somewhere in building related to the sodium coolant cycle, but was unable to tell them *where*. By now the Monju FBR may not exactly qualify as "modern", but at least there were already PCs when it was designed.

Presumably the regulating bodies will now recommend all exising nuclear plants to be upgraded by installation of redundant automatically triggered HTEDBAFs (Hydrogen Tanks for Emergency Direct Building Access Facilitation) on the service spaces.

To be fair, at least one pipe to refill the unit 4 pool was only destroyed by the hydrogen explosion. Unit 2 which didn't have its bulding top blown away has always been topped up using the pool cleaning and cooling system, as far as I know.

According to the status reported on the GRS site, on June 16 the unit 4 pool became the last to be switched from the Putzmeister concrete truck pump back to the pool cooling and cleaning system for refilling. They're adding 150 t of water every other day.

 

[etudiant]

Please, are there some data as to oceanic radioactive contamination from Fukushima ? I have not seen anything lately, but I see that the Kuroshio carries to Alaska where McDonalds does get most of the fish fillets.

sigyn

Latest TEPCO data is here: http://www.tepco.co.jp/en/press/corp-com/release/11062008-e.html
The sea report from a Woods Hole Oceanographic cruise off Japan to measure the radiation is here: https://www.whoi.edu/page.do?pid=67796

Note that the TEPCO data is very local, whereas the Woods Hole study is wide area oriented. Unfortunately, it does not appear that there will be any speedy conclusions released from the Woods Hole study, but rather a series of research papers. That may take many months.
That is what we have, it does not really begin to answer your question.

 

[MiceAndMen]

As for access, I think they mean access to spray water.

That was my thought as well. I've certainly been tripped up before by inaccurately parsing English translations of Japanese text. A lot of nuance can be lost in translation, and it doesn't help that a lot of information seems to be ambiguous even in the original Japanese. I've learned, more or less, to wait for further comments or clarification regarding what is being said exactly.

I'm fairly disgusted that the IAEA has chosen to exclude journalists and, by extension, the public from their meeting in Vienna this week with TEPCO and other representatives of various agencies in Japan. In the early weeks before the government took over the press conferences, it was said that the foreign journalists there in Japan were the only ones asking pointed questions or asking for clarification of certain statements. With IAEA's decision to hold this week's talks in secret, we'll no doubt be left with a single narrative when all is said and done, having no chance to pose followup questions or challenge any inconsistencies. That's assuming, of course, that news organizations would have anyone on hand capable of understanding enough of what was being said to ask such questions at an open forum. That is highly doubtful, now that I think about it, so maybe the closed meeting isn't such a travesty after all. On the other hand, it gives the impression that they have something to hide and are gathered in Vienna this week to make sure they all get their stories straight.

As in all things since 11 March, time will tell.

 

[tsutsuji]

http://www.asahi.com/national/update/0621/TKY201106210195.html & http://www3.nhk.or.jp/news/html/20110621/t10013661011000.html : This morning at 7:20 AM a pump that brings water to adjust the concentration of one of the chemicals in the Areva system automatically stopped after detecting the water flow was too high. It was started again in the afternoon after adjusting the water flow.

http://www.asahi.com/national/update/0621/TKY201106210195.html : Only 8 days are left until the storing capacity for contaminated water is full.

http://news.tv-asahi.co.jp/ann/news/web/html/210621016.html : It is expected that a 100 mm rain would result into a 68 mm rise of the water level in the turbine building at unit 2.

http://news.tbs.co.jp/newseye/tbs_newseye4756438.html TEPCO decided to slow down the flow of cooling water at the reactors of unit 1, 2 and 3 by injecting 0.5 to 1 ton per hour less than was previously injected, saying the plant parameters are stable enough.

 

[joewein]

Please, are there some data as to oceanic radioactive contamination from Fukushima ? I have not seen anything lately, but I see that the Kuroshio carries to Alaska where McDonalds does get most of the fish fillets.

The Kuroshio merges with the Oyashio and becomes the North Pacific Current, which crosses the North Pacific from East to West, then splits up and flows down the California coast or up the British Columbia coast / Alaska panhandle. So the Kuroshio does not go to Alaska directly, not all of it heads there and not all that gets there is from the Kuroshio.

I did a quick search on the speed of the current. One study involving buoys and drift nets suggested it would take debris about a year to float across the the North Pacific. The distance for the North Pacific crossing is similar to traveling the US coast to coast twice.

My choice whether or not to eat at McDonald's would be based on factors other than possible traces of cesium in their deep fried fish fillet. I think people are far more likely to die from clogged arteries or diabetes or other health problems than any effects from radioactivity when eating convenience food year after year.

 

[jlduh]

Please, are there some data as to oceanic radioactive contamination from Fukushima ? I have not seen anything lately, but I see that the Kuroshio carries to Alaska where McDonalds does get most of the fish fillets.

sigyn

Radiation is used to keep food safe and free from bacterials, so don't worry, in case of McDonald's this will be an improvement...

 

[MadderDoc]

Has anyone seen a time line of when building radiation levels became too high to allow human entry? <..>

The best bid for a comprehensive timeline that would include this kind of information -- to the extent that the data exists -- would be the Appendix 2 referred to in this page:
http://www.tepco.co.jp/en/press/corp-com/release/11061805-e.html
E.g. for unit 1 it appears to be reported there that an employee on March 12th 11:39 JST entered the building and was exposed to 106.3 mSv (that's the doserate per hour, assumedly). The document is so far unfortunately only available in Japanese.

Alternatively a timeline for the venting procedures could be constructed from the timelines reproduced in the Japanese Government Report to the IAEA -- the venting timing could then be used as proxy for the timing of the release of radioactive contamination to the buildings. A more distant proxy might be produced using data from the radiation monitoring posts around the plant.

 

[GJBRKS]

http://www.asahi.com/national/update/0621/TKY201106210195.html : Only 8 days are left until the storing capacity for contaminated water is full.

The projection has been 7-8 days every day since thursday last week ,
some process variables are not being updated here.

 

[tsutsuji]

http://mainichi.jp/select/weathernews/news/20110621dde001040059000c.html : as part of the solutions implemented to solve the high radiation problem at the Kurion system, tests were performed today setting a three times higher target value for cartridge change.

The projection has been 7-8 days every day since thursday last week ,
some process variables are not being updated here.

They must have been able to decontaminate a few hundred tons, if they were able to run two lines of the purification system for 5 hours the first time, then perform some tests during many more hours. Or perhaps the calculation includes the added capacity of the new tanks that were supposed to be delivered every day or so.

http://news24.jp/articles/2011/06/21/07184912.html : The test which started this afternoon is performed with a 50 ton/hour flow.

 

[MadderDoc]

TEPCO is considering walls to be built into the ground around the plant to isolate the groundwater.

See text and illustrations on page 11 on:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110617e4.pdf

It is a well known technique for containing groundwater contamination, but has many failure modes, and very much depends on the implementation and the exact conditions for escape of the contamination through cracks and permeable layers in the underground. As a long term solution it would need supplementing with capping at the surface to avoid further rainwater infiltration -- not readily apparent though how that could be feasible in the case of Fukushima -- and/or a system for pumping up of the contaminated groundwater plume for decontamination -- but, to be sure Tepco does not appear to need more water for decontamination for quite some time yet.

 

[MadderDoc]

Well I for one never was... :-)

that personal opinion apart, discharging radioactive water into the Pacific is not feasible, Corea and China would be raising too harsh protests, maybe if nothing else proves possible they will try with the megafloat as a temporary storage...

it could may be fail later on, but an accident will be in any case more tolerable than a deliberate act...

probably building another more stable facility would have been a safer and more stable option than makeshift containers...

do you think they ruled that out till now because of costs or because of time constraints ?

Catching up to congratulate you for being the poster of the ten thousandth post to this thread!

Thought experiment: If this were my planet, and I had the unfortunate Fukushima moment, would I not eat all shame of having acted so stupidly, then dump the crap in the great sink of the Pacific, get on with living with the consequences, hopefully wiser by the experience ? Would that not be the most rational thing for me to do?

 

[zapperzero]

So, what fact is expressed here? Is it perchance an expression of cause and effect? Or is it an expression of timing of events? The answer is blowing in the wind.

are we to understand that high radiation at the plant already from the morning of March the 12th made it impossible to send a man to each service floor to check the situation around the pools? Is that a fact or is it hokum? Are we to understand that absent the saving grace of three explosions it would have been impossible to gain 'access' to those pools? Access? Exactly what kind of 'access' are we talking about? Access in the sense that one now could (only) look into the pools from a safe distance in a helicopter, what kind of access is that?

Yes I am sure I am overreacting. Calm down old bear.

I've had posts moved to the political thread before, so I'm trying to refrain from commenting on the performance of the various actors. Yes, I think they mean to say it was cause and effect. Something broke in the unit 2 normal venting path because of the unit 3 explosion.

Also, yes, that's the ony reason for which SFPs would have been inaccessible prior to the explosions.

Of special note also, the headcount. According to the report, there were little more than 400 people on site when the earthquake happened, most of them working on unit 4. Fukushima Dai-ichi was running a skeleton crew, for some reason.

 

[MadderDoc]

I've had posts moved to the political thread before, so I'm trying to refrain from commenting on the performance of the various actors. Yes, I think they mean to say it was cause and effect. Something broke in the unit 2 normal venting path because of the unit 3 explosion.

And that is fair dinkum? So, based on the IAEA report are we now allowed, indeed compelled, on this thread to take it as established fact by the highest nuclear authority that the unit 3 explosion rendered a unit 2 valve inoperable? Which valve, btw -- the statement of inoperability of 'the valve' makes reference to the previous statement, in which reference is made to two different valves. I think you get my drift, a reader of a technical document is not supposed to need to interpret the text as were it poetry.

 

[tsutsuji]

http://www.zakzak.co.jp/society/domestic/news/20110621/dms1106211654023-n1.htm : The Japan Meteorological Agency announced that the tsuyu rain season had begun today in the Tohoku region (which comprises 6 prefectures in the North-East of Japan, including Fukushima prefecture). For Fukushima prefecture, this is 9 days later than an average year. Heavy rains pouring 30 mm per hour were deemed possible today in the region.[PLAIN]http://www.jma.go.jp/en/radame/imgs/prec/205/201106211530-00.png
Rain map from http://www.jma.go.jp/en/radame/index.html?areaCode=205

 

[zapperzero]

And that is fair dinkum? So, based on the IAEA report are we now allowed, indeed compelled, on this thread to take it as established fact by the highest nuclear authority that the unit 3 explosion rendered a unit 2 valve inoperable? Which valve, btw -- the statement of inoperability of 'the valve' makes reference to the previous statement, in which reference is made to two different valves. I think you get my drift, a reader of a technical document is not supposed to need to interpret the text as were it poetry.

I'll take a stab at interpreting the poetry. AFAIR, units 2 and 3 vent through the same stack and there is a Y junction. I'm going to go out on a limb here and say that the unit 3 blast jammed shut a valve that is on the Unit 2 side of that junction, outside the reactor building and that operators may or may not have succeeded in venting into the #2 reactor building.

 

[Jorge Stolfi]

To be fair, at least one pipe to refill the unit 4 pool was only destroyed by the hydrogen explosion. Unit 2 which didn't have its bulding top blown away has always been topped up using the pool cleaning and cooling system, as far as I know. According to the status reported on the GRS site, on June 16 the unit 4 pool became the last to be switched from the Putzmeister concrete truck pump back to the pool cooling and cleaning system for refilling. They're adding 150 t of water every other day.

If there had been no explosion, would it have been possible to activate the #3 SFP cooling equipment? The primary containment of #3 seems to be leaking into the (former) service space, so if the building had not exploded it would have been filled with radioactive steam from the top down, through the fuel chute and stairwells.

In contrasts, the leak of #2's primary containment seems to be in the suppression chamber, right? So the escaping steam is perhaps being scrubbed, with most its radioactivity going into the basement water rather than into the building's atmosphere. If that is true, then, without the explosion of #3, the contamination inside it could have been worse than that in #2. Does this make sense?

 

[MadderDoc]

I'll take a stab at interpreting the poetry. AFAIR, units 2 and 3 vent through the same stack and there is a Y junction. I'm going to go out on a limb here and say that the unit 3 blast jammed shut a valve that is on the Unit 2 side of that junction, outside the reactor building and that operators may or may not have succeeded in venting into the #2 reactor building.

Well. a) Unit 2 and 3 do not vent through the same stack. b) to be consistent with the Japanese Government report to the IAEA, the inoperable valve in question would be one of the S/C side valves, i.e. a valve deep down in the bowels of the beast, in the basement floor of unit 2.