Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[triumph61]

1. Picture: look at the right side. The upper Part is visible.
2. Picture : The upper Part is no longer visible.
3. Picture: Left side, maybe there is the upper part of the FHM.

 

[Rive]

Oooops. Yes, you are right. That thing on the third picture is the trolley of the FHM.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120307/0920yoken.html At a symposium in Washington about the Fukushima Daichi accident, Commissioner Apostolakis said "the consequences of a tsunami could have been predicted". The symposium organiser, the Carnegie Endowment for Peace, is also releasing a report on "Why Fukushima was preventable", saying that the analysis of historical tsunamis was not sufficient and that in contrast with the measures taken in Europe after the French NPP flooding and blackout of 1999 or in the US after the 11 September 2001 attacks, Japan was negligent to take countermeasures against blackout.

http://carnegieendowment.org/2012/03/06/one-year-on-assessing-fukushima-s-impact/9iid Symposium

http://carnegieendowment.org/files/fukushima.pdf report: James M. Acton and Mark Hibbs, "Why Fukushima was preventable"

 

[etudiant]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120307/0920yoken.html At a symposium in Washington about the Fukushima Daichi accident, Commissioner Apostolakis said "the consequences of a tsunami could have been predicted". The symposium organiser, the Carnegie Endowment for Peace, is also releasing a report on "Why Fukushima was preventable", saying that the analysis of historical tsunamis was not sufficient and that in contrast with the measures taken in Europe after the French NPP flooding and blackout of 1999 or in the US after the 11 September 2001 attacks, Japan was negligent to take countermeasures against blackout.

http://carnegieendowment.org/2012/03/06/one-year-on-assessing-fukushima-s-impact/9iid Symposium

http://carnegieendowment.org/files/fukushima.pdf report: James M. Acton and Mark Hibbs, "Why Fukushima was preventable"

Seems nuclear management in Japan after thirty plus years of operations free from disaster suffered from the same 'Victory Disease' as that which afflicted Japanese leadership in the early days of WW2.
It is very hard to stay careful when things work well for a long time.

 

[jmelson]

As I understand this for unit 4 they will use external cranes only to move the transfer casks to- and from the pool, and they will repair and use the FHM to move the fuel within the pool to the transfer casks.

But first they will have to repair the FHM of the common pool and start to prepare it to receive the removed fuel from unit 4.

Ok, that seems a lot safer, but the problem is that repairing the FHM and being sure it is completely reliable will be a huge effort, due to the structural damage to the entire building. The FHM itself could be pulled out by crane and moved elsewhere for repairs, but the tracks it runs on have to be guaranteed to handle the load and be transited in so the FHM can travel in the proper plane.

Jon

 

[jmelson]

Seems nuclear management in Japan after thirty plus years of operations free from disaster suffered from the same 'Victory Disease' as that which afflicted Japanese leadership in the early days of WW2.
It is very hard to stay careful when things work well for a long time.

See also Challenger accident and Columbia accident. "It hasn't killed anybody yet, so it can't be a big risk."

Jon

 

[mheslep]

See also Challenger accident and Columbia accident. "It hasn't killed anybody yet, so it can't be a big risk."

Jon

That's a half-appropriate comparison. Yes organizations can and have misjudged the risk of accidents, but clearly the consequences of the one (Challenger) means 100% fatalities, while the other with containment equipped reactors means large capital losses and economic damage, but zero fatalities, so far.

 

[jmelson]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20120307/0920yoken.html At a symposium in Washington about the Fukushima Daichi accident, Commissioner Apostolakis said "the consequences of a tsunami could have been predicted".

Wow, what an understatement! Anybody who was analyzing safety should have put this together pretty easily. It seems the Japanese government allowed TEPCO WAY too much
leeway to set their own rules and safety management.

But, of course, anybody who was let into give Fushima Dai-ichi #1 a complete review
would have demanded it be shut down immediately. And, the rest of the plants there would have only gotten a slightly better review. There were so MANY features of the plant that compromised survivability, it would have made it almost impossible to bring these plants up to reasonable standards. Once you put practically the entire electrical safety system in the basement of a building only meters from the ocean, both horizontally and verticaly, you have a HUGE problem. Then, there was so much ELSE vulnerable to the tsunami, like EDG fuel tanks. Just a mess. Fixable, but it would cost a couple billion $ to retrofit just the plants
at this one location.

Jon

 

[jmelson]

That's a half-appropriate comparison. Yes organizations can and have misjudged the risk of accidents, but clearly the consequences of the one (Challenger) means 100% fatalities, while the other with containment equipped reactors means large capital losses and economic damage, but zero fatalities, so far.

There indeed WERE fatalities at the plant, although not related to safety systems, but just
people being at the lower levels of the buildings when the tsunami came in. it is kind of a miracle
nobody was killed by falling debris, etc. when the explosions happened.

This accident has caused major radioactive contamination of a large area of Japan, deaths are really hard to associate with such an event, but this is a HUGE, widespread consequence that is not over yet. Radioactive soil will be dug up and cause further contamination for years to
come. There are still areas where farming is not permitted, produce will need to be tested
for radioactivity for years, it is a HUGE mess. The entire nation of Japan will have a big power shortage this summer, it will be interesting to see how they cope with it. It is definitely affecting their whole national economy.

But, I was mostly trying to draw a comparison between assessing risk in very complicated systems, and the cultures that manage such systems.

Jon

 

[mheslep]

There indeed WERE fatalities at the plant, although not related to safety systems,

Though not related to anything having to do with nuclear power.

 

[clancy688]

but clearly the consequences of the one (Challenger) means 100% fatalities, while the other with containment equipped reactors means large capital losses and economic damage, but zero fatalities, so far.

So you're saying that seven dead people are worse than 100.000 displaced people, hundreds of square kilometres literally lost and economic losses in the range of dozens or hundreds of billions of dollars?

Oh, of course, from a purely naive and moralistic view, of course, the seven dead are way worse. Since, they are dead and all those displaced still have their lives and human lifes can't be compared to money anyway...

But that's wrong. Life is no pony farm. Those seven astronauts died and with them billions of tax money disintegrated, but then there's no major future impact to the lifes of other people. They may be dead, but it doesn't affect anyone except their families and NASA managers.
As for Fukushima, nobody died, that's right. But hundreds of thousands of lifes are HEAVILY affected, you could even say derailed - for DECADES. Millions, if you count the economic ramifications in.

 

[al2207]

Though not related to anything having to do with nuclear power.

at least 1 worker was killed when tsunamis, hit he was investigating if there were some damage from earthquake

 

[etudiant]

There is clearly a problem in maintaining alertness, whether individually or in large organizations, in a long term situation.
Afaik, the SSBN program in the US Navy has done so pretty well, certainly better than the USAF's SAC counterpart, now melded into a generic 'Strike Command['. This latter group was in the news a few years back because a B52 with a half dozen live nukes on board hopscotched across the US, oblivious to the detailed rules on nuclear weapons transport. The head of the USAF was relieved as a result.
My guess is that a periodic human sacrifice of that type is essential to maintain focus.
If so, the problem of the Japanese nuclear program is that they allowed too few flaming public failures. If someone had been pilloried after the leaks at the Monju breeder project for instance, instead of a general whitewash, I am sure the managers at Fukushima would have been more vigorous in demanding better tsunami defenses.
I might add that imho the current Japanese government's insistence that 'no one was responsible' for this disaster guarantees a bigger one next time.

 

[Cire]

So you're saying that seven dead people are worse than 100.000 displaced people, hundreds of square kilometres literally lost and economic losses in the range of dozens or hundreds of billions of dollars?
.

Why don't you ask if any of the 100,000 displaced people would rather be dead instead of displaced. I think we know the answer.

 

[jmelson]

My guess is that a periodic human sacrifice of that type is essential to maintain focus.
If so, the problem of the Japanese nuclear program is that they allowed too few flaming public failures. If someone had been pilloried after the leaks at the Monju breeder project for instance, instead of a general whitewash, I am sure the managers at Fukushima would have been more vigorous in demanding better tsunami defenses.
I might add that imho the current Japanese government's insistence that 'no one was responsible' for this disaster guarantees a bigger one next time.

The Fukushima plant was not "defendable", in my opinion. Defenses might have helped, but the whole plan of the system was so fatally flawed that it would have taken insane
effort to protect the plant as it was sited. And, fixing one of the major flaws would have required getting practically all the electrical equipment out of the basement. This plant could have been damaged by a major leak in a similar manner, it doesn't have to be a tsunami.

Well, as for the future, at least so far, many of the older coastal plants are now shut down, and it may be politically impossible to restart those, even if they wanted to.

Jon

 

[jmelson]

Though not related to anything having to do with nuclear power.

There WILL be fatalities from this accident, but it will be essentially impossible to know which persons died from it. In five, ten or maybe twenty years there will be a clear increase of cancers and related diseases. It certainly won't be a HUGE increase, like those laughably insane reports that there were already tens of thousands of deaths in the US that were circulating on some wacko blogs last fall. But, there is quite likely to be a measurable and statistically significant effect on the Japanese population, given the sizable radiation dose that was released.

Jon

 

[tsutsuji]

As for Fukushima, nobody died, that's right.

I answer in the other thread at https://www.physicsforums.com/showpost.php?p=3804367&postcount=512

 

[swl]

..clearly the consequences of the one (Challenger) means 100% fatalities, while the other with containment equipped reactors means large capital losses and economic damage, but zero fatalities, so far.

There have been plenty of fatalities related to the release of radiation from the three meltdowns, fires and explosions at Fukushima 1.

There was a huge evacuation as result of the ongoing radiation release. During this evacuation, many people died. It is readily apparent that there is a connection between these events.

http://mdn.mainichi.jp/features/archive/news/2011/04/20110426p2a00m0na006000c.html

It is obvious there has been tremendous property, and psychological damage as well.

I recommend the contamination & consequences thread if you are interested in learning about some of the dangers of nuclear power.

 

[Astronuc]

Some background recently published.

Unit 1
Cycle    BOC Date     EOC Date
  25   03 Nov 2007  17 Oct 2008
  26   18 Apr 2009  25 Mar 2010
  27A  29 Jul 2010  22 Aug 2010
  27B  27 Sep 2010  11 Mar 2011

Unit 2
Cycle    BOC Date    EOC Date
  23   28 Jan 2007  12 Mar 2008
  24   24 May 2008  22 Apr 2009
  25A  21 Jun 2009  17 Jun 2010
  25B  19 Jul 2010  16 Sep 2010
  26   18 Nov 2010  11 Mar 2011
  
Unit 3
Cycle    BOC Date    EOC Date
  22   07 Jul 2006  31 Aug 2007  Outage: 15 Jun - 2 Aug
  23   14 Dec 2007  24 Feb 2009
  24   10 Jul 2009  19 Jun 2010
  25   23 Sep 2010  11 Mar 2011

Unit 4
Cycle    BOC Date    EOC Date
  22   02 May 2007  28 Mar 2008
  23   17 Jul 2008  29 Sep 2009
  24   30 Nov 2009  30 Nov 2010  Shutdown 101 days before tsunami
  
Unit 5
Cycle    BOC Date    EOC Date
  22A  13 Nov 2006  20 Feb 2007
  22B  26 Apr 2007  20 Jan 2008
  23   22 Jun 2008  01 Sep 2009
  24   02 Nov 2009  02 Nov 2010 Shutdown 67 days before tsunami
  
Unit 6
Cycle    BOC Date    EOC Date
  20   06 Jun 2006  30 Sep 2007
  21   08 Feb 2007  11 Mar 2009
  22   12 Jun 2009  14 Aug 2010 Shutdown 209 days before tsunami

The units were mostly on annual cycles, although units 5 and 6 were managing 13 to 14 month cycle lengths.
Unit 4, Cycle 23 was ~14.5 mo, Cycle 24 was 12 month.

Refueling/Maintenance outages were long by current (modern) standards. The plants were operating at original ratings and had relatively low capacity factors by modern standards. I'll post the source later.

 

[Yamanote]

Are there any news about the cause of the explosion of unit3?

I didn't follow this issue for quite some time...
For units 1 and 4 I think the explosions were caused most likely by hydrogen within the reactor building.

 

[r-j]

Nuclear Disaster In Japan Could Have Been Mitigated, Say Industry Insiders

http://www.nytimes.com/2012/03/10/w...-of-nuclear-disaster.html?_r=1&pagewanted=all

 

[zapperzero]

http://pbadupws.nrc.gov/docs/ML1205/ML12052A109.pdf
NRC transcript from the 17th

And there is a notable point -- 300 feet
2 above Unit 3 in the air there is a dose reading of
375 R per hour.

 

[jim hardy]

http://pbadupws.nrc.gov/docs/ML1205/ML12052A109.pdf
NRC transcript from the 17th

Heavily redacted, lots of speculation , very much in line with chaotic conditions back then..

Misinformation about state of unit 4 spent fual pool, they thought it was gone
speculation on conditions

mean, the dose sounds like not as much
2 a shine from the building as when the building blew
3 up. There is spent fuel and pellets and whatever all
4 over the place around the plant. So they are taking
the bulldozers through and pushing the rubble in
6 piles, and they are saying that's cutting the dose
7 down, you know, 60, 70 percent.

p 74, and i wouldn't bet much on that being accurate.

Are there any news about the cause of the explosion of unit3?

Even the Frontline show was silent on that one.

 

[SteveElbows]

Personally I don't see the point in taking any of those details from the early days transcript seriously. Because its an experience we all went through in our own way at various stages of talking about the events on forums such as this one. Loads of confused details, stuff that turned out to be dead wrong, or speculation that may have lead somewhere interesting but for which no subsequent evidence emerged with which to build upon.

Now its always possible that previously undisclosed information will be released that will give cause to reconsider something, but when it comes to stuff such as explosions I would think it more likely that the knowledge about this stuff will not be greatly expanded upon, not directly anyway. For example if you are interested in the reactor 3 explosion then I am not quite sure what you are hoping to discover about the explosion. The timing of the explosions at both reactors 1 & 3 happening not long after venting is pretty compelling, and there is an uncontroversial source of hydrogen, several ways for the hydrogen to get into the buildings upper floors, and well understood triggers for that hydrogen to explode. The most you will get is that one day we are going to hear some more detail about factor 3's spent fuel pool, and the state of the fuel there could potentially renew a discussion about this pool having played a role in events at reactor 3 building. And at some point we might get a little more info about containment failure.

 

[jim hardy]

Personally I don't see the point in taking any of those details from the early days transcript seriously. Because its an experience we all went through in our own way at various stages of talking about the events on forums such as this one. Loads of confused details, stuff that turned out to be dead wrong, or speculation that may have lead (led?) somewhere interesting but for which no subsequent evidence emerged with which to build upon.

Thanks for saying it more eloquently.

That's where i am at too, we just don't know.
I'm done with speculating.
Waiting to see what pans out.

 

[zapperzero]

Personally I don't see the point in taking any of those details from the early days transcript seriously.

All the other numbers I've seen in there jive with TEPCO/NISA and later reports. The interpretation is all NRC, of course, and some of it turned out to be quite wrong.

 

[zapperzero]

The most you will get is that one day we are going to hear some more detail about rector 3's spent fuel pool, and the state of the fuel there could potentially renew a discussion about this pool having played a role in events at reactor 3 building.

Well I happen to think I just posted such a detail.

 

[SteveElbows]

Well I happen to think I just posted such a detail.

Well I was meaning new detailed information about the pool and its contents, but certainly the rate you mention is of interest to this question.

I'm not used to working with R per hour numbers, did a conversion but am unsure if I did it right or not. Is 375 R/hour = 3.75 Sieverts/ hour?

 

[NUCENG]

Well I was meaning new detailed information about the pool and its contents, but certainly the rate you mention is of interest to this question.

I'm not used to working with R per hour numbers, did a conversion but am unsure if I did it right or not. Is 375 R/hour = 3.75 Sieverts/ hour?

Your conversion is correct. 1 Sv = 100 Rem.

Well I happen to think I just posted such a detail.

ZZ, your detail is without context . A radiation reading was taken above the Unit 3 and, and if correct, was recorded at 3.75 Sv/hr. That is the detail. The context requires interpreting what the detail tells us. Was the high radiation due to loss of shielding water level from the spent fuel pool? Was the level from a release plume from damaged fuel in the SFP? Was the drywell Cap displaced? Was the level from shine from the drywell? Was the level from an ongoing release plume due to containment leakage? If the radiation was from I-131 it would indicate recently irradiated fuel. If it was all gamma radiation it would indicate shine instead of a plume. What is the radiation level today? We don't know enough to really say what it meams.

 

[zapperzero]

Well I was meaning new detailed information about the pool and its contents, but certainly the rate you mention is of interest to this question.

It says "strong possibility of uncovered fuel" to me.

I'm not used to working with R per hour numbers, did a conversion but am unsure if I did it right or not. Is 375 R/hour = 3.75 Sieverts/ hour?

100 Rem is 1 Sv, yes.

 

[zapperzero]

The context requires interpreting what the detail tells us. Was the high radiation due to loss of shielding water level from the spent fuel pool? Was the level from a release plume from damaged fuel in the SFP? Was the drywell Cap displaced? Was the level from shine from the drywell? Was the level from an ongoing release plume due to containment leakage? If the radiation was from I-131 it would indicate recently irradiated fuel. If it was all gamma radiation it would indicate shine instead of a plume. What is the radiation level today?

There is at least some context - it was measured from a JSDF helo and so it is, must be, all gamma, because that's all the military cares about - how long can their soldiers operate the equipment. It's not likely at all that someone bothered to pop a probe out the window just for the thrill of counting beta decays. In fact, I'd wager good money that they were buttoned up.

Look at that anemic plume of steam, hard to believe that the helo is getting 3 Sv/h from that (and if it was, people on the ground would have been getting it too), it's not like they are flying directly through:



The reactor well cap was not displaced, that we know of.

As for the radiation level today, that is also unknown. There are reports of dose rates on-site decreasing very significantly after the pools were watered.

 

[SpunkyMonkey]

This may be the missing Unit 3 refueling crane fallen into the spent-fuel pool as seen in an April, 14 2011 image here:

The graphic shows similar objects between this piece of wreckage in the Unit 3 pool and the intact Unit 4 refueling crane. It also shows a similar spatial conjunction of similar objects, and this meta-similarity makes me confident we're looking at Unit 3's refueling crane.

There are many pre-tsunami photos of the refueling crane here.

Why isn't the proposed refueling crane also bright green? My guess is that the fire that blasted out the south side over the pool and thus onto the crane scorched off the paint.

 

[SteveElbows]

Thanks for the additional info. I'm sort of with NUCENG with this one, in so much as I am hesitant to attribute the reading to a particular source with any great certainty. Especially as they were high enough in the air that I cannot claim that they were only measuring stuff that must be related directly to reactor 3.

I'm basically still stuck at the point of being able to say that the fuel pools are still of interest, and that reactor 3's pool may be more interesting than reactor 4's. I expect that at some point we will learn more about this, but I doubt I am going to figure much more out in the meantime.

 

[tsutsuji]

It says "strong possibility of uncovered fuel" to me.

Sorry for asking again what was probably mentioned a dozen times in this thread, but:

Was there no instrumentation telling the SFP water level in real time, or was that instrumentation broken ?

I have the same question about temperature instrumentation.

If the fuel uncovered, how ? Was the water splashed out during the earthquake ? Or during the explosion ?

 

[SteveElbows]

This may be the missing Unit 3 refueling crane fallen into the spent-fuel pool as seen in an April, 14 2011 image

Sorry but that photo is a pretty poor analysis, the objects in the photo are a poor correlation for the circular items of the fuel handling bridge.

People did spend a lot of time looking at a variety of photos around reactor 3 for signs of the refuelling bridge. No useful conclusions were formed, other than being able to say that its not intact above the pool like reactor 4's is.

Some bits of it could be in the pool, but its also quite possible that it was ejected from the reactor building. And not necessarily dramatically either, it may have blown out in such a way that it did not travel high into the sky, but rather toppled south and fell to the ground between reactors 3 & 4, and area where quite radioactive debris was detected and dealt with later. And we know from the level of information given out over the course of the disaster that they were unlikely to bother telling the public the detail of what the debris consisted of. People were also interested in the hole in the roof of reactor 3 turbine building.

Given the size of the explosion at reactor 3 building, I am really not sure that we could expect to learn anything useful from the final resting spot of the refuelling bridge anyway.

 

[SteveElbows]

Sorry for asking again what was probably mentioned a dozen times in this thread, but:

Was there no instrumentation telling the SFP water level in real time, or was that instrumentation broken ?

I have the same question about temperature instrumentation.

If the fuel uncovered, how ? Was the water splashed out during the earthquake ? Or during the explosion ?

The way that the SPF water level is measured is one of the weaknesses that the disaster revealed. Even at the best of times it seems that such information was not easily obtained without actually being on the refuelling floor. And its more often obtained by looking for signs that the pool has overflowed into the skimmer surge tank, rather than measuring the water level directly.

As for how it came to run out of water, the decay heat of the fuel causing it to boil away is the main area of focus. Obviously if the pool lost integrity and leaked then this would be another way that water level could be lost, but even if the pool remains intact the water is still lost at quite a high rate once the pool reaches a certain temperature.

 

[SteveElbows]

I need some help with some relatively short Japanese documents that were released in October but were written in the days following the disaster.

Specifically these two documents that are to do with neutron detection, can you give me an overview of what they say?

http://www.jnes.go.jp/content/000119688.pdf

http://www.jnes.go.jp/content/000119689.pdf

Also this one which mentions drywall vent pipe & pits:

http://www.jnes.go.jp/content/000119681.pdf

 

[jim hardy]

I remember those days well.

I felt at the time the pool level was getting low and there was significant "shine" up through the little water left, and backscatter down was reason for high readings near building. They got the "elephant" there just in time and readings came down as they watered the pool.

Also if i recall correctly there was what looked to me like the missing crane near top of the debris pile on N side of Unit-3, itself pretty well covered by rubble.

Not to turn this thread back into the Unit 3 explosion thread.
Just my 2 cents worth of memories from last year.

Was the water splashed out during the earthquake ? Or during the explosion ?

I think it's safe to presume the explosion caused some leaks that lowered level. Sloshing during quake probably put contaminated water in basement early on.
I am not ready to make a strong claim whether fuel got uncovered, though I think it didnt.
Someplace there's radionuclide analysis of SFP water and that was my basis for that.

Still waiting on that Nova show.

 

[SteveElbows]

Also if i recall correctly there was what looked to me like the missing crane near top of the debris pile on N side of Unit-3, itself pretty well covered by rubble.

No, that device got plenty of attention here, its the carousel that's used for retensioning the bolts of the reactor or containment cap (I forget which at this precise moment in time).

 

[SteveElbows]

Looks like the temperature sensor for reactor 2 RPV Supporting skirt upper part has started to fluctuate more in the last few days:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/12031212_temp_data_2u-e.pdf

Seems they are going to send a remote camera vehicle into spent fuel pool of reactor 4 to look at the debris, and they are also considering moving the control rods from the fuel pool to the reactor at some future point when they start to tackle the fuel in that pool.:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_120312_01-e.pdf

 

[r-j]

This may qualify as a dumb question, but I must ask. It's been almost a year since the explosion of building three. From what I read, it seems there is no information about the state of the spent fuel storage pool that used to be inside the containment building.

Is that true?

A related question. If there is no evidence of the condition, is there any scientific reason not to snake a camera in there and look at it?

Which brings up another question. Could the condition of fuel pond be verified in any other way?

 

[NUCENG]

There is at least some context - it was measured from a JSDF helo and so it is, must be, all gamma, because that's all the military cares about - how long can their soldiers operate the equipment. It's not likely at all that someone bothered to pop a probe out the window just for the thrill of counting beta decays. In fact, I'd wager good money that they were buttoned up.

Look at that anemic plume of steam, hard to believe that the helo is getting 3 Sv/h from that (and if it was, people on the ground would have been getting it too), it's not like they are flying directly through:



The reactor well cap was not displaced, that we know of.

As for the radiation level today, that is also unknown. There are reports of dose rates on-site decreasing very significantly after the pools were watered.

You may be right, but look at what you said.

"it is, must be, all gamma, because that's all the military cares about." I'm not sure that assumption is true based on my military service. Do we know what type of dosimetry they had on the helicopter?

"Look at that anemic plume of steam," Water vapor (steam) is not radiation. A radiation plume does not have to be visible to be deadly. In fact gas releases are likely to be invisible,

"if it was, people on the ground would have been getting it too" Depending on wind speed, direction, and atmosppheric stability and the temperature of the released plume, people on site at ground level may not have been as exposed. If it was shine from the SFP or the drymell the surrounding concrete and debris could have provided shielding to personnel at ground level.

"The reactor well cap was not displaced, that we know of." Exactly!

Are these alternative explanations true or false? I don't know, but they illustrate that your conclusions include inherent assumptions that we cannot yet verify. That is the best service this forum has provided - allowing ideas to be introduced and hypotheses to be tested.

 

[tsutsuji]

The way that the SPF water level is measured is one of the weaknesses that the disaster revealed.

Thanks for your reply. Were there SFP temperature readings available at that time ?

 

[duccio]

A radiation reading was taken above the Unit 3 and, and if correct, was recorded at 3.75 Sv/hr.

4 Sv/hr 100 meters above reactor 3, should we take this reading seriously? Maybe right on top of exhaust stack during dry venting, but it's two orders of magnitude higher than the other readings taken 100 meters from the building

 

[SteveElbows]

Thanks for your reply. Were there SFP temperature readings available at that time ?

Not during the time that they most needed such readings. They had to resort to using infrared camera from a helicopter to estimate the pool temperatures during the week that they were most concerned about the pools.

For example with unit 4 pool they had a temperature reading of 84 degrees C around March 14th, but after that they did not get another proper temperature reading from that pool for a very long time.

 

[SteveElbows]

This may qualify as a dumb question, but I must ask. It's been almost a year since the explosion of building three. From what I read, it seems there is no information about the state of the spent fuel storage pool that used to be inside the containment building.

Is that true?

A related question. If there is no evidence of the condition, is there any scientific reason not to snake a camera in there and look at it?

Which brings up another question. Could the condition of fuel pond be verified in any other way?

Thats not the case. There has not been any fascinating new information about reactor 3 pool for ages, but there was information supplied ages ago.

They did some analysis of the water to see what levels of various radioactive substances were in it.

They also stuck a camera into it and published the video, probably about 10 months ago now. Unlike the video of the pool at reactor 4, its very hard to see anything useful in this video, because the pool has lots of debris in it.

 

[zapperzero]

You may be right, but look at what you said.

"it is, must be, all gamma, because that's all the military cares about." I'm not sure that assumption is true based on my military service. Do we know what type of dosimetry they had on the helicopter?

Nope. We don't know. We probably won't ever find out. What do you think is more likely to have been used, internally mounted AN-VDR 2 that is standard JSDF gear or some sort of scout setup with an external probe?

"Look at that anemic plume of steam," Water vapor (steam) is not radiation. A radiation plume does not have to be visible to be deadly. In fact gas releases are likely to be invisible

So you're thinking clouds of Iodine? Why would it take a different path than the water vapor?

"if it was, people on the ground would have been getting it too" Depending on wind speed, direction, and atmospheric stability and the temperature of the released plume, people on site at ground level may not have been as exposed.

Yeah you're right.

If it was shine from the SFP or the drywell the surrounding concrete and debris could have provided shielding to personnel at ground level.

Yep. The decrease in dose rates after water was poured provides circumstantial evidence of this.

"The reactor well cap was not displaced, that we know of." Exactly!
Are these alternative explanations true or false? I don't know, but they illustrate that your conclusions include inherent assumptions that we cannot yet verify. That is the best service this forum has provided - allowing ideas to be introduced and hypotheses to be tested.

I'd hate to call them conclusions. More like hypotheses. But yes, I like to believe that what we're doing here is useful

 

[Rive]

"The reactor well cap was not displaced, that we know of." Exactly!

Even some parts of the top concrete plug were spotted under the rubble. So physical displacement can be excluded.

However: as we learned from case of U2 both the equipment hatch plug and the top concrete plug/containment cap likely released pressure: and in case of U3 steady steam plumes were spotted on the early videos around the reactor well. It's not known if they were from the RPV or the drywell, but possibly they can explain some wild radiation readings.

Ps.: U3 RPV is which is on atmospheric pressure, am I right?

4 Sv/hr 100 meters above reactor 3, should we take this reading seriously? Maybe right on top of exhaust stack during dry venting, but it's two orders of magnitude higher than the other readings taken 100 meters from the building

IMHO yes. There was those steam plumes... And in those early days there was also the more mobile Iodine with the Cesium... I wonder if the birds were checked for contamination afterwards.

 

[clancy688]

4 Sv/hr 100 meters above reactor 3, should we take this reading seriously? Maybe right on top of exhaust stack during dry venting, but it's two orders of magnitude higher than the other readings taken 100 meters from the building

We can certainly say that at least the JSDF did take those readings seriously. You only try your luck in filling the SFPs with dropped water from high altitude fly-overs if there's something so absolutely nasty in the air above the reactors that even hovering (and thus enormously improving your aim) for a couple of seconds is out of the question.

 

[clancy688]

Unit 4 Spent Fuel Pool:

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201203080066 "Fukushima No. 4 reactor saved by upgrade mishap"

According to the article, there was no separator gate in place between the Spent Fuel Pool and the Reactor Well, allowing for 1000 additional tons of water to flow to the SFP. Was that fact already known?