Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[zapperzero]

The latest by Dr. Michio Ishikawa - Passage to Core Solidification

http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110808.html

I hadn't read this. I have now, due to alpi's post. Here's an excerpt:

The other option is air-cooling.This involves suspending the current cooling operation to let the core melt further and drop on the bottom of the containment vessel so as to increase the surface area before resuming cooling. Implementing this option requires the examination of several technical challenges, including the prevention of steam explosion.It is possible to safely implement this approach, but the implementation requires courage and meticulous care.

Umm... wait, what? Is this guy for real?

 

[LabratSR]

The cited article is dated April 11. In view of later announcements of possible melt-throughs, it is of limited relevance.

EDIT: Upon further reading, I found this gem:

That's about it for this person's credibility, as far as I am concerned.

http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110620.html

 

[rmattila]

A report from 1988 concerning filtered venting capabilities of US plants:

http://www.osti.gov/energycitations/servlets/purl/6945722-maXGrD/6945722.pdf

Within the United States, the only commercial reactors approved to vent during severe accidents are boiling water reactors having water suppression pools. The pool serves to scrub and retain radionuclides. The degree of effectiveness has generated some debate within the technical comnunity. The decontaminatlon factor (DF) associated with suppression pool scrubbing can range anywhere from one (no scrubbing) to well over 1000 (99.9 % effective). This wide band is a function of the acciaent scenario and composition of the fission products, the pathway to the pool (through spargers, downcomers, etc.), and the conditions in the pool itself. Conservative DF values of five for scrubbing in MARK I suppression pools, and 10 for MARK II and MARK III suppression pools have recently been proposed for licensing review purposes. These factors, of course, exclude considerations of noble gases, which would not be retained in the pool.

Venting procedures as used within the EPGs are intended as a "last resort" operator action. Uncontrolled increases in the containment temperature or pressure will result in containment failure with unknown results. Therefore, it is felt that a controlled action with defined consequences is preferable to no operator action. The methodology to establish the venting pressure is an equally important consideration. Ideally, the venting pressure could be established solely on the actual pressure capability of the
containment. That would delay venting until the last possible time and minimize unnecessary releases. However, considerations associated with actual operating plant constraints tend to reduce the venting pressure (based on the PCPL). As a result, there are plant-to-plant differences in EOPs. This is best demonstrated by looking at the selection of the valves that are in the flow paths to be used for venting. Plants have provided a table of penetrations that will be used in the event of a serious accident. The accepted philosophy is to begin opening valves in the smallest flow path, starting with wetwell penetrations. Failing successful control of the transient, the operator is to increase the diameter of valves that are opened sequentially until even drywell valves (resulting in an unscrubbed release) would become candidates. One licensee has also proposed venting the wetwell through the spent fuel pool to enhance fission product scrubbing after core damage.

The first vent system was assumed to be similar to the 18" wetwell hard pipe to ductwork system at Peach Bottom [6].
Similar to the Peach Bottom plant, the pressure is relieved through the nitrogen purge system ductwork, which is expected to fail. For the purpose of a general evaluation of venting strategies, it was assumed that the vent system can be safely opened both before and after vessel failure and without existing on-site AC or DC power. Basically, this was a vent system which discharges into the reactor building (RB) upon actuation. Expert evaluation in NUREG/CR-4551 [7] indicated that the reactor building decontamination factors (DFs) probably range from 1.5 to 2.5 in the absence of a hydrogen burn. Although these DFs are small, source term studies indicated that they do play a role in the offsite consequences. Conversely, hydrogen burns in the RB were hypothesized to sweep out the fission products rapidly with little or no DF. Expert opinion solicited in NUREG/CR-4551 estimated a 20% probability of complete bypass of the RB (DF=1.0) during hydrogen burns. As shown in Table 1, another disadvantage of discharging directly into the RB is the potentially adverse effect on recovery equipment.

This report was published one year prior to the http://www.nrc.gov/reading-rm/doc-collections/gen-comm/gen-letters/1989/gl89016.html requiring the installation of hardened vents in BWRs with MARK I containment.

 

[zapperzero]

http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110620.html

Is there a point you're trying to make?

 

[etudiant]

Is there a point you're trying to make?

Not to speak for labratSR, but I was struck by Dr Ishikawa's willingness to to accept much higher exposure levels for the general public. It is true that there are areas with 30 or more mSv/yr of natural radioactivity in India where people have lived for centuries with no apparent damage. That does not make it wise to just up the permissible exposure levels for a new population. Add to this his idea that the government should buy their output and you can see the nuclear ghetto being created.
Imho, Dr Ishikawa is not providing the level of actionable guidance that one might have expected from a man of his expertise and background. Perhaps because he is so aware of the horrendous risks that may befall a country based on his own wartime experience, he appears to be more comfortable with risks than the Japanese public. That is causing a widening disconnect between his comments and actuality, leaving him increasingly isolated.

 

[hellbet]

I hadn't read this. I have now, due to alpi's post. Here's an excerpt:

Umm... wait, what? Is this guy for real?

M. Ishikawa is really a very smart guy, now what if the "melted core" has already dropped to the confinement vessel and one stop the water? Now the corium will really be out of control... Maybe Tepco/Nisa know that evidence and consequently do "nothing" because there is nothing to do?

Whatever M. Ishikawa has a long and strong background in industry i invite anyone to ponder about... He might be just missing some crucial information about the corium but whoever knows about?

 

[LabratSR]

Is there a point you're trying to make?

Just trying to show the whole story.

 

[LabratSR]

If anyone is interested, I stumbled across an ORNL paper that I have not seen posted here before (sorry if it has been) and I find to be very informative(at least to me). In particular, Appendix D.

Human Factors Review for Severe Accident Sequence Analysis

http://pbadupws.nrc.gov/docs/ML1031/ML103140169.pdf

 

[MiceAndMen]

EDIT: And thank you, tsutsuji. You are really doing a great job to keep many people up-to-date of the data that sometimes is quite difficult to obtain from other sources here at the other side of the world.

My thanks to tsutuji as well. Without his valuable contributions this thread would be dead and buried by now. Instead, it continues to be a source of good up-to-date information regarding the Fukushima NPPs.

 

[MiceAndMen]

EDIT: To add: if there was ongoing criticality, it should lead to a wide number of short-lived isotopes being generated, such as I-135 and Xe-135, and their presence would be a certain indication of a recent criticality. On the other hand, I am not sure how TEPCO:s analysis and reporting routines would contribute to presence of such isotopes becoming reported. It appears that only I-131, Cs-134 and Cs-137 are routinely reported, but I don't know it a more complete gamma analysis is made on routine samples.

I think one of the "lessons learned" that everyone should take away from this mess going forward, is that regular "more complete gamma analyses" need to be done and the results publicized in any future incidents. TEPCO has routinely provided monitoring reports ONLY on I-131, Cs-134 and Cs-137 for months now. That is not enough, and in the future competent authorities and responsible agencies and business interests must not be allowed to point to TEPCO's example as justification for limited reporting. I would hope scientists and engineers (and lay people as well) both in and outside the nuclear power industry begin to champion this view. TEPCO is setting a bad precedent here and should not be allowed to get away with it, so to speak.

 

[gmax137]

... It is true that there are areas with 30 or more mSv/yr of natural radioactivity in India where people have lived for centuries with no apparent damage. That does not make it wise to just up the permissible exposure levels for a new population...

Are you suggesting that the Indians in that area are somehow adapted to the higher dose rate? Is there any evidence of that?

 

[etudiant]

Are you suggesting that the Indians in that area are somehow adapted to the higher dose rate? Is there any evidence of that?

Absolutely no idea on adaptation and evidence would not be easy to find..
Afaik, there have been no studies on the topic and even the basic public health data is pretty spotty, as this is a pretty poor area. There are similar high natural radioactivity sites also in parts of southern China and Brazil, likewise in fairly impoverished areas.
That said, it just seems imprudent to say that because we cannot see impact at 30mSv/yr, it is reasonable to use that as an incremental threshold.

 

[NUCENG]

Absolutely no idea on adaptation and evidence would not be easy to find..
Afaik, there have been no studies on the topic and even the basic public health data is pretty spotty, as this is a pretty poor area. There are similar high natural radioactivity sites also in parts of southern China and Brazil, likewise in fairly impoverished areas.
That said, it just seems imprudent to say that because we cannot see impact at 30mSv/yr, it is reasonable to use that as an incremental threshold.

See:
http://www.angelfire.com/mo/radioadaptive/ramsar.html

 

[htf]

Let's see if this posting is also deleted ...

TEPCO management knew about the tsunami threat and did nothing:

http://mdn.mainichi.jp/mdnnews/news/20110825p2g00m0dm050000c.html

I said this in a posting two weeks ago and received a warning from Astronuc to "refrain from such noise" and my posting was deleted. Now it is official "noise".

 

[etudiant]

See:
http://www.angelfire.com/mo/radioadaptive/ramsar.html

Thank you for the link.
A very interesting document. It seems the topic is getting some study after all.
That said, I doubt most Western research protocols would allow a 1 Gray dose to be administered to unrelated subjects for baseline comparison purposes. That is probably why similar work has not been done by Western institutions, at least afaik. We are probably mostly using the database created from prompt exposure measurements during the nuclear testing era, rather than from chronic exposure.

 

[NUCENG]

TEPCO management knew about the tsunami threat and did nothing:

http://mdn.mainichi.jp/mdnnews/news/20110825p2g00m0dm050000c.html

I said this in a posting two weeks ago and received a warning from Astronuc to "refrain from such noise" and my posting was deleted. Now it is official "noise".

We discussed this on the Management and Government Performance Thread in May and it has come up again there today. Tsutsuji has added some excellent references showing that this was true. I have to believe there was more to the deletion of your post than a simple statement. The mentors have deleted posts and locked threads that I disagreed with, but they are doing a tough job and they have their reasons.

 

[NUCENG]

I am double posting this link here and on the Fukushima Management and Government Performance thread. It has technical information about robots as well as a potential indication of censorship.

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

Here is a link to a story about one of the robot operators at Fukishima. This is a summary because a blog the operator was writing has been deleted. Perhaps another example of trying to prevent communication in a world where the internet makes that impossible and foolish.

http://spectrum.ieee.org/automaton/robotics/industrial-robots/fukushima-robot-operator-diaries

 

[skodises2]

Well, that didn't take long. I get a 404 error from that link: "Page Not Found". And I am a 25+ year member of the IEEE... Hope somebody got a snapshot of it before it was taken down.

 

[Borek]

NUCENG posted incorrect link in this post, it is corrected now.

 

[NUCENG]

NUCENG posted incorrect link in this post, it is corrected now.

Ooops. Thanks Borek!

 

[LabratSR]

Analysis Results From The Spent Fuel Pools

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110825_02-e.pdf


Background Concerning The Evaluation Of Wave Sources

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110825_01-e.pdf

 

[Bodge]

Analysis Results From The Spent Fuel Pools

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110825_02-e.pdf


Background Concerning The Evaluation Of Wave Sources

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110825_01-e.pdf

As per usual, just three isotopes measured.

There will be dozens of others and they never tell us the levels. I don't believe that they are not testing for strontium, cobalt and the actinides.

Also, ph 9.2 in SPF 3 seems a little high compared to the others: why is this? TIA

 

[joewein]

ph 9.2 in SPF 3 seems a little high compared to the others: why is this? TIA

Because of the amount of broken concrete rubble in the pool of unit 3, which is highly alkaline. Cement reacts with CO2 at the surface of the concrete, but inside there's still a lot of CaO that will raise pH when exposed.

 

[rmattila]

As per usual, just three isotopes measured.

There will be dozens of others and they never tell us the levels. I don't believe that they are not testing for strontium, cobalt and the actinides.

You don't measure isotopes separately, but rather measure the entire gamma spectrum and then recognize different isotopes from the spectrum by their signature gamma peaks. Strontium is not a gamma emitter, so it requires a separate (and rather lengthy) beta analysis to be detected.

If you know the measurement arrangements and get the raw gamma spectrum, you could make the spectrum analysis anywhere around the world, as there are several organizations with very sophisticated analysis capabilities.

 

[tsutsuji]

http://www.tepco.co.jp/en/press/corp-com/release/11082602-e.html Yesterday, near unit 3, most likely, "an oil pipeline for cooling was damaged by accidental removal of an oil pipeline for radiator of the transformer during the removal work of debris". Picture available at http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110825_06-e.pdf

http://www.yomiuri.co.jp/science/news/20110826-OYT1T00779.htm A pump carrying water from the Kurion system to the Areva system made an automatic stop at 2:21 PM, 26 August. Tepco is investigating the cause of the overload. [If it is a "temporary stop", as Yomiuri says, it could mean that the pump has already been restarted. However, there is no such hint in Tepco's latest press release at http://www.tepco.co.jp/nu/f1-np/press_f1/2011/htmldata/bi1714-j.pdf which also says the (Kurion) adsorption system is stopped]

 

[tsutsuji]

I have begun to read the big Fukushima Daini report that was published on 12 August : http://www.tepco.co.jp/cc/press/betu11_j/images/110812b.pdf

I think the 16 diagrams on pages 33 to 40 (pdf page numbers) explaining what happened at the four units at four different dates are quite helpful to figure out what happened, and to easily compare the lucky unit 3 with the more unlucky other units.

Unit 1, 11 March after quake, before tsunami: page 33 top
Unit 1, 11 March after tsunami: page 33 bottom
Unit 1, 14 March recovery of RHRS and RHRC pumps, start of RHR pump B (S/P cooling): page 34 top
Unit 1, 14 March 17:00 cold shutdown: page 34 bottom

Unit 2, 11 March after quake, before tsunami: page 35 top
Unit 2, 11 March after tsunami: page 35 bottom
Unit 2, 14 March recovery of RHRS and RHRC pumps, start of RHR pump B (S/P cooling): page 36 top
Unit 2, 14 March 18:00 cold shutdown: page 36 bottom

Unit 3, 11 March after quake, before tsunami: page 37 top
Unit 3, 11 March after tsunami: page 37 bottom
Unit 3, 12 March start of reactor cooling: page 38 top
Unit 3, 12 March 12:15 cold shutdown: page 38 bottom

Unit 4, 11 March after quake, before tsunami: page 39 top
Unit 4, 11 March after tsunami: page 39 bottom
Unit 4, 14 March RHRS and RHRC pumps, plant status upon recovery of power supply (S/P spray): page 40 top
Unit 4, 15 March 7:15 cold shutdown: page 40 bottom

The key to the English acronyms is given on pages 763, 764, 765 and 766.

I attach below an English translation of the first diagram (Unit 1, 11 March after quake, before tsunami: page 33 top)

The most important clue is that equipment in use is colored in red. Idle equipment is blue, and unusable equipment is shown with a black "X" symbol.

Yellow boxes are backup electric power supplies (power cables or mobile diesel generators)

 

[tsutsuji]

The Kurion system was restarted :

http://www.tepco.co.jp/en/press/corp-com/release/11082702-e.html "At 4:54 pm we resumed the instruments by switching to transfer pump (B) for cesium absorption treated water. At 5:45, it reached normal volume of flow."

Third and last instalment of the earthquake safety study, now for units 2, 5 and 6:

http://www.tepco.co.jp/en/press/corp-com/release/11082605-e.html English (summary only)
http://www.tepco.co.jp/cc/press/betu11_j/images/110826c.pdf (65 pages, not translated into English) page 50 shows a series of pictures inside unit 5.

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110824e13.pdf Water treatment weekly report for the 17 - 23 August week. 6,780 m³ (or 80,7% of 50 m³/h*24hours*7days=8400 m³) have been treated, including 1,760 m³ treated by SARRY.

 

[rmattila]

Radiation measurement results from unit 4 emergency gas treatment system:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110827_02-e.pdf

It appears that the filters have a clearly higher level of activity on the side of the common exhaust stack of units 3/4, and a smaller activity on the unit 4 side. If the filters are identical, this would apparently support the theory of unit 3 hydrogen finding its way to unit 4 through the common stack connection.

 

[ernal_student]

I am sorry that I have been unable to contribute in recent weeks, but I have been abroad and will have to go on another extended trip before long.

By the way, if I may ask, I would like to ask whether anybody sees any major problems (data that have been shown to be invalid or invalid conclusions) in the following summarizing article:
http://www.gaia-health.com/articles501/000517-fukushima-no-return-home.shtml

Thank you in advance for your help.

 

[LabratSR]

I am sorry that I have been unable to contribute in recent weeks, but I have been abroad and will have to go on another extended trip before long.

By the way, if I may ask, I would like to ask whether anybody sees any major problems (data that have been shown to be invalid or invalid conclusions) in the following summarizing article:
http://www.gaia-health.com/articles501/000517-fukushima-no-return-home.shtml

Thank you in advance for your help.

For me, a simple Google search of the authur told me all I need to know.

http://www.naturalnews.com/Author32.html

 

[zapperzero]

Radiation measurement results from unit 4 emergency gas treatment system:

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110827_02-e.pdf

It appears that the filters have a clearly higher level of activity on the side of the common exhaust stack of units 3/4, and a smaller activity on the unit 4 side. If the filters are identical, this would apparently support the theory of unit 3 hydrogen finding its way to unit 4 through the common stack connection.

It would support the theory of air on one side being less radioactive than air on the other side.

 

[hbjon]

How's the battle with the fuku monster going? Giant Robot activate? Thanks in advance for the tireless work you all do.

 

[etudiant]

Has anyone developed a scenario that explains the sizable emission of plutonium/neptunium from the site?

According to the NISA report of June 6 (hat tip to EX SKF, http://ex-skf.blogspot.com/ ) the accident has dispersed 3.2x10**9 bequerels of plutonium.
While this is not a lot, it does raise the question of how this non volatile material was mobilized for dispersal. Other than molten fuel vaporizing, are there other plausible explanations?

 

[zapperzero]

Has anyone developed a scenario that explains the sizable emission of plutonium/neptunium from the site?

According to the NISA report of June 6 (hat tip to EX SKF, http://ex-skf.blogspot.com/ ) the accident has dispersed 3.2x10**9 bequerels of plutonium.
While this is not a lot, it does raise the question of how this non volatile material was mobilized for dispersal. Other than molten fuel vaporizing, are there other plausible explanations?

Well, they are both (in their metal form) somewhat soluble in water. During the meltdown, some of the metal oxide gets reduced and seawater is mildly alkaline. I don't know if it's the only mechanism, but some of the plutonium mst have left with the steam.

 

[tsutsuji]

http://www3.nhk.or.jp/news/genpatsu-fukushima/20110829/index.html Today 10 workers are going to enter inside Fukushima Daini unit 4 primary containment vessel. They are going to check radiations, temperatures, check if anything is broken, preparing for future work there. It is the first time people enter inside a Fukushima Daini primary containment vessel since 11 March.

How's the battle with the fuku monster going? Giant Robot activate? Thanks in advance for the tireless work you all do.

On the Fukuichi live camera, you can see that the two lower levels steel truss beams have already been assembled surrounding Fukushima Daiichi unit 1 : http://www.tepco.co.jp/en/nu/f1-np/camera/index-e.html (you can compare with the structure diagram on http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110614e17.pdf )

While the new SARRY system had its trouble on 26 August, at the Kurion system :

Vessels in the Water Treatment Facility were exchanged (the Water Treatment Facility was not suspended) (from 11:01 to 13:58, August 26).
http://www.nisa.meti.go.jp/english/press/2011/08/en20110829-2-1.pdf

Without even suspending one of the two lines (or half of the facility)? Remembering the early days of the Kurion system when it was said that flushing had to be performed during long hours before vessel change, I was not aware they were now able to perform vessel change at the Kurion system without suspending the whole facility.

http://sankei.jp.msn.com/region/news/110829/fks11082912150003-n1.htm A thermometer located at the junction between the RPV and the RPV cap at Fukushima Daiichi unit 2 is displaying 120°C on 29 August instead of 72°C on 28 August. As the other thermometers and pressure gauges are OK, the thermometer is probably having a dysfunction.